Engineered phages for electronics

Author’s Accepted Manuscript Engineered Phages for Electronics Yue Cui

www.elsevier.com/locate/bios

PII: DOI: Reference:

S0956-5663(16)30517-6 http://dx.doi.org/10.1016/j.bios.2016.05.086 BIOS8776

To appear in: Biosensors and Bioelectronic Received date: 15 March 2016 Revised date: 29 May 2016 Accepted date: 30 May 2016 Cite this article as: Yue Cui, Engineered Phages for Electronics, Biosensors and Bioelectronic, http://dx.doi.org/10.1016/j.bios.2016.05.086 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Engineered Phages for Electronics Yue Cui1,2 1

Department of Electrical Engineering and Computer Systems, University of Cincinnati, Cincinnati, OH 45221

2

Department of Mechanical and Materials Engineering, University of Cincinnati, Cincinnati, OH 45221 *Corresponding author E-mail: [email protected] Tel: 513-556-1985 Fax: 513-556-7326

Abstract Phages are traditionally widely studied in biology and chemistry. In recent years, phages have attracted significant attentions for functionalization or construction of electronic devices, due to the specific binding, catalytic or electronic properties of the displayed peptides on the coat proteins of phages. To apply the engineered phages in electronics, these are a number of interesting questions: how to select or express peptides on phages for electronics? How are the

1

engineered phages characterized? How to assemble materials with engineered phages? How are the engineered phages micro or nanopatterned? What are the strategies for constructing specific sensors, battery, or piezoelectric devices with engineered phages? This review will highlight our early attempts to address these questions. Here, we explore the fundamental and practical aspects for selection or expression of specific peptides on phage coat proteins, characterization methods for the selected phage displayed peptides in electronics, the assembly of electronic materials, and development of a variety of engineered phages-based electronic devices, such as sensors, and energy devices. Keywords: Phages, electronics, self-assembly, patterning, sensors, energy devices

Introduction Electronic materials have been of great importance in the construction of a variety of electronic-based devices such as diodes (Azam et al. 2015; Yoshida and Yoshizaki 2015), transistors (Schwierz et al. 2015; Wang et al. 2012), etc. Electronic materials include metal (Ma et al. 2016; Rinaldi and Carballo 2016), metal oxide (Qin et al. 2015; Yalovega et al. 2016), alloys (Boukamp et al. 2004), inorganic semiconductors (Wang et al. 2016b; Zarhri et al. 2016), organic semiconductors (Takagi et al. 2016; Yang et al. 2016), conducting polymers (Lee et al. 2015; Pławińska et al. 2016), dielectric materials (Kahraman et al. 2015; Shi et al. 2015), nanomaterials (Benchirouf et al. 2016; Kim et al. 2016), etc. These materials have been widely used for applications in sensors (Amiri et al. 2016; Tomer et al. 2016), actuators (Hu et al. 2016b; Zhou et al. 2016), circuits (Ha et al. 2014; Wu et al. 2013), solar cells (Lan et al. 2016;

2

Yang et al. 2016; Zhang et al. 2016), displays (Nobeshima et al. 2013; Wu et al. 2012), etc. Biological materials can offer the advantages of excellent biocompatibility, biodegradability, high selectivity for binding or catalytic capabilities, etc. The functionalization and assembly of electronic materials into functional systems with specific biological materials can be used to construct selective sensors, implantable electronic devices, low cost energy storage or harvesting devices, etc. Peptides are specific, robust biological recognition molecules with broad chemical diversity, which can survive through high and low temperatures, and acid or base solutions. Peptides play important roles in many biological processes, and process many identification or catalytic functions, which can be valuable for a variety of applications in materials and device constructions. Besides, peptides can be further conjugated with other peptide, nucleic acid or polymer sequences to form multifunctional networks, which possess multiple binding or catalytic motifs to form complex, self-assembled hybrid conjugates with a variety of materials (Fang et al. 2009; Sarikaya et al. 2003; Whaley et al. 2000). Several types of phages have been studied for generating engineered phages, including M13, f1, fd, etc (Sattar et al. 2015). M13 phage is widely used as an engineered phage, which has different types of proteins on its coat, including pIII, pVI, pVII, pVIII, and pIX proteins, each of the pIII, pVI, pVII, and pIX is present at 5 copies on M13 phages, and pVIII is present at ~2700 copies (Lee et al. 2012; Nam et al. 2006). All these proteins can be engineered to express certain peptides for electronic applications. Phage display has emerged as a powerful approach for identifying a variety of specific peptide motifs on the coat proteins, generally on pIII, which process the capability for selectively binding to target materials or catalyzing the synthesis of target materials. In phage display, a library of approximately a billion peptide variants is

3

displayed on the phage surface, which allows for rapid, combinatorial screening of sequences displaying high binding affinities or catalytic abilities toward specific targets. Through the biopanning process, the phage display technology can screen out specific peptides for recognizing target materials. Further, through recombinant DNA, certain peptides can be displayed on the coat protein of pVIII to possess specific properties, including binding, catalytic, and piezoelectric properties. The phage particles with specific peptide sequences on pVIII proteins can be templates for the formation of hybrid materials. The spatial control of engineered phages has attracted great interest, which can further control the multifunctional peptide assembled hybrid materials. These can broaden the range of material properties and device properties, and open up new opportunities for wide range applications in sensors, actuators, batteries, cell biology, surface science, etc. Microscale and nanoscale patterning can improve the precise control of the location of engineered phages. A variety of patterning techniques have been used to combine with engineered phages, including photolithography (Horiuchi et al. 2003), e-beam lithography (Donthu et al. 2005), photolithography and controlled etching (Cui et al. 2010a), and plasma etching generated wrinkle patterns soft lithography (Cui et al. 2010b), etc. Further, engineered phages have been used for several types of electronic device constructions, including sensors (Arter et al. 2010; Cui et al. 2010a; Wu et al. 2010), batteries (Lee et al. 2009; Nam et al. 2006), and piezoelectric devices (Cung et al. 2013; Lee et al. 2012). Phage displayed peptides, or peptide-displayed phages can exhibit specific binding, catalytic, or electronic properties, which is a critical step for the device construction. By using engineered phages to functionalize the surfaces of conventional electronic materials, or construct new types

4

of electronic materials, different types of electronic devices can be developed, including sensors, and energy devices. Here, we will focus on the recent progress of phage display for electronic materials and devices, including the protocol for selection of selective phage displayed peptides for binding or catalyzing specific electronic materials, the characterization methods, the assembly of electronic materials, the patterning of phage displayed peptides with electronic materials, the constructions of biomimetic peptide sensors, phage assembled battery, and piezoelectric energy devices. Phages are traditionally widely studied in biology and chemistry, and there are a variety of review papers about phages in biology and chemistry areas, such as biofilm control (Motlagh et al. 2016), immunotherapy (Zhao et al. 2016), interaction with host (Mahony et al. 2016), etc. However, there are very limited reviews in electronics or electronic related areas. Recently, we presented a review about biomimetic nanosensors (Cui et al. 2012), which focuses on peptides in nanosensor area. Here, this work for the first time focuses on engineered phages in electronics, including how to select or engineer phages, and how to use these engineered phages to functionalize or construct different types of electronic materials and devices. This review explores the methodologies and opens up exciting opportunities for the development of a variety of new electronic materials and electronic devices based on engineered phages for future applications. Selection or expression of peptides on phages for electronics Identifying specific peptide sequences is a critically important first step in the development of novel electronic hybrid materials and devices. Via millions of years of evolution, Nature develops specific peptides for target analytes as “naturally occurring peptides”. For example, immune systems have evolved and contained a number of peptides, and thousands of 5

antimicrobial peptides have been identified which generally contain cell-binding motifs. Insect antenna possesses some odorant binding peptides that can bind and ferry odorant molecules from the external environment. However, these peptides are evolved and identified for binding some specific targets, which are unsuitable for binding to the large amounts of target materials existed in the world. In order to select specific peptides for binding to target materials, biological libraries have been used for the selection of target-binding peptides, which can be practically used for a variety of large amounts of target materials. “Biological peptide library” refers to “phage display library”, “bacterial display library”, or “mammalian cell display library”. The library contains millions of phages or bacteria or mammalian cells with random peptides displayed on their surfaces, and therefore a library can contain millions of different peptide sequences. Highaffinity peptides to a wide range of materials can be identified form the natural selection protocol from the combinatorial libraries. For a specific target, a biopanning process will be performed with the library to screen selective peptide displayed phages or bacteria or mammalian cells. However, using the bacterial display library or mammalian increases the non-specific binding due to the large amount of proteins displayed on the bacteria surface. Phage is single-stranded DNA virus that can infect bacteria. A short DNA sequence is inserted into the phage DNA, and a peptide sequence encoded from the short DNA sequence will be expressed on the phage coat protein. M13 phage is a typical phage, as shown in Figure 1a (Lee et al. 2009). There are several types of coat proteins on phage surfaces, pIII and pVIII proteins are widely used to engineer electronic materials. By modifying the DNA sequence to further modify a peptide sequence in either of pIII or pVIII coat protein, the phage particle can display unique properties. pIII coat proteins can possess specific binding or catalytic peptide

6

sequences, which can be identified by an vitro screening process from a combinatorial library. Besides, by recombinant DNA technology, pVIII coat proteins can display catalytic peptide motifs, which can mediate the assembly of nanomaterials on phage particles. Table 1 summarizes the methods for selection or expression of peptides on phage coat proteins. As shown in Figure 1b, phage display is widely studied to identify selective peptide sequences on the pIII coat protein for binding to an electronic material (Sarikaya et al. 2003). Usually, a phage display library is incubated with a target substrate, followed by washing to remove the unbound phages. The phages are then eluted from the substrate surface by addition of glycine-HCl, neutralized with Tris-HCl. Eluted phages are then amplified in E. coli, and amplified phages are collected for the next round of biopanning. The panning process is repeated for several rounds to obtain phage clones expressing peptides with the highest binding affinities to the target substrate. After the final round of panning, DNA sequence analysis of the isolated phage clones yielded target-binding peptides. A wide range of electronic materials were studied as the targets for phage display technology to identify the specific peptide-binding motifs, such as metals and metal oxides, semiconductor materials, polymers, and nanomaterials. The metals could be Ag (Chan et al. 2006), Au (Nergiz et al. 2013), Pd (Heinz et al. 2009), TiO2 (Chen et al. 2006; Seo et al. 2006), ZnS (Mao et al. 2003), CdS (Mao et al. 2003), Al (Zuo et al. 2005), steel (Zuo et al. 2005), etc. The semiconductor materials include Si (Estephan et al. 2011b), SiO2 (Chen et al. 2006), ZnO (Golec et al. 2012), InP (Estephan et al. 2009), GaN (Estephan et al. 2008), InN (Estephan et al. 2011a), etc. The polymers could be polypyrrole (Nickels and Schmidt 2013), chlorone-doped polypyrrole (Sanghvi et al. 2005), poly(3-hexylthiophene-2,5-diyl) (Li et al. 2014), etc. The nanomaterials could be carbon nanotube (Yu et al. 2012), graphene (Cui et al. 2010a), etc. These

7

peptides can be further conjugated with other peptide, nucleic acid or polymer sequences to form multifunctional networks, which possess multiple binding or catalytic motifs to form complex, self-assembled hybrid materials (Fang et al. 2009; Sarikaya et al. 2003; Whaley et al. 2000). Besides, phage display technology is studied for the identification of catalytic peptides from the pIII coat protein. Figure 1c shows the catalytic growth of ZnO with phage-displayed peptides (Wei et al. 2011). To select specific catalytic peptides, the phages are first incubated with the precursor. The growth of nanocrystals from the precursor is due to the catalytic effect of phage-displayed peptides, which catalyze the formation of nanocrystals. With centrifugation, the phages bounded nanocrystals are collected, and the residual phage viruses are released from the nanocrystals with glycine-HCl buffer. The eluted phage displayed peptides are then amplified, followed by an additional biopanning. After several rounds of biopannings, highly catalytic phage displayed peptides can be selected. However, there have limited peptides on PIII proteins screened phage display libraries for catalyzing the formation of nanocrystals. Further, M13 phages can be genetically engineered to display certain peptide motifs on the 2700 copies of the pVIII coat proteins. Generally they are made of negatively charged aminoacid glutamate (E), from 1E to 4E. Triglutamate (EEE) and tetraglutamate (EEEE) have been widely studied for fusing to the pVIII coat protein. The expressed peptide motifs on pVIII coat proteins can nucleate different types of materials onto the phage particles to assemble new types of materials (Cung et al. 2013; Lee et al. 2009; Nam et al. 2006) or exhibit special electronic property – piezoelectric property (Lee et al. 2012). These assembled materials could be Au and Ag noble metals and their alloy nanowires (Chen et al. 2013; Lee et al. 2010), Co3O4 (Ghosh et al. 2012; Nam et al. 2006), Au-CO3O4 (Nam et al. 2006), FePO4 (Lee et al. 2009; Moradi et al. 2015), CoMn2O4 (Oh et al. 2014), MnCo2O4 (Oh et al. 2014), CoMn2O4 (Oh et al. 2014),

8

BiO0.5F2 (Oh et al. 2012), PZT (Cung et al. 2013), nickel (Neltner et al. 2010), rhodium (Neltner et al. 2010), and ceria (Neltner et al. 2010). The above methods have been successfully used for several types of electronic materials for the construction of new types of electronic materials and electronic devices. However, there are still a large amount of other electronic materials, which do not have existing specific binding or catalytic peptide motifs. These selection or expression methods of peptides on phages can open up new opportunities for study of various electronic materials and their construction of electronic materials. Characterization of engineered phages in electronics The characterization methods are the tools for knowing the existence and properties of engineered phage particles or phage displayed peptides, and understanding the effects of engineered phages on electronic materials or electronic devices. Engineered phages can be used for developing new materials or devices in future studies, and characterization methods are always essential for studies related to phages in electronics. Several characterization techniques have been widely used for characterizing the binding or catalytic effects of peptide-displayed phages (peptide with the phage particle), synthetic peptides (without the phage particles) on electronic materials, including fluorescent immunoassay (Swaminathan and Cui 2013), AFM (Cui et al. 2010a), circular dichroism (CD) (Kuang et al. 2010), SEM (Cui et al. 2010a; Swaminathan et al. 2014), TEM (Mueller et al. 2015), and contact angle measurement (Swaminathan et al. 2014), etc. Some other methods, such as absorbance immunoassay, fluorescence polarization assay, have been widely used for characterizing phage-displayed peptides used in molecular biology, but these are not common methods for electronic materials.

9

Table 2 shows the typical characterization methods for engineered phages or phage assembled materials. Fluorescent immnoassay and AFM are widely used to characterize the direct binding of peptide-displaying phages to electronic materials. CD can be used to characterize the structure of the peptides to determine the contents and fractions of certain structures. AFM, SEM, TEM, XRD, and EDX can be used to characterize the assembled materials via engineered phages or synthetic peptides with bining motifs identified from phage display. Contact angle analysis can be used to characterize the change of surface peroperty due to the presence of phage-displayed peptides, synthetic peptides, or assembled materials. Fluorescent immunoassay is widely used for characterizing the peptide-displaying phages for binding to target analytes, with either fluorescent assay or absorbance assay. Fluorescent characterization of the binding of peptide-displaying phages are generally accomplished by incubating the substrates sequentially with (1) the phage-displayed peptides, (2) blocking buffer (containing BSA), (3) biotin-conjugated antibody M13 anti-phage antibody, and (4) streptavidin or avidin conjugated fluorescent dye (e.g. FITC), with TBS buffer washing steps in between to remove non-specific binding. The fluorescent signal on the substrate indicates the binding of peptide-displaying phages. AFM can visualize the peptide-displaying phages or assembled materials via phage displayed peptides on target substrates. M13 phage has a length of about 900 nm and a diameter of about 6.5 nm, and thus after binding to the target substrate, under AFM image, it appears as a thin line, as shown in Figure 2a (Cui et al. 2010a). Besides, the synthetic multifunctional peptides have multiple binding or catalytic motifs identified from phage display which can assemble other materials onto substrate, and the assembled materials can change the surface roughness of substrate and be observed by AFM (Cui et al. 2010a).

10

CD is the difference in the absorption of left-handed circularly polarised light and righthanded circularly polarised lightand occurs when a molecule contains one or more chiral chromophores (light-absorbing groups). CD can characterize the structure of the peptides to determine the contents and fractions of certain structures, for example, α-helix, β-sheet, β-turn, and random coil. PIASPIC peptide is bifunctional peptide with a binding motif to SWCNT identified from phage display (Kuang et al. 2010). Figure 2b shows the CD spectra for PIASPIC peptide on SWCNTs, and in the presence of peptide on SWNTs, the CD spectra of the SWCNTs clearly showed a change (Kuang et al. 2010). SEM is widely used for the characterization of phage-assembled materials via phagedisplayed peptides or peptide-displaying phages. Figure 2c shows the SEM image of the assembly of silver particles with multifunctional peptides, and the multifunctional peptide consists of a binding motif to target substrate which is identified from a phage display library, and a catalytic motif to synthesize nanoparticles (Swaminathan et al. 2014). The presence of assembled materials on the target substrate indicates the binding of phage-displayed peptides to target substrate. Similarly, TEM is used for characterization of the assembly of materials with engineered phages. The expressed peptides on the phage coats can assemble other materials onto the phage particles to form nanowires, and the TEM image of the nanowires can indicate the presence of specific peptide motif on the phage coats, as shown in Figure 2d (Lee et al. 2009). XRD is studied for characterizing the self-assembled crystalline materials on phage particles too. Trough the displayed pVIII proteins in phage particles, inorganic crystalline materials can be assembled on the phage particles, which can show relevant peaks in the XRD

11

spectrum, as shown in Figure 2e (Cung et al. 2013). Besides, EDX can analyze the elemental composition of the assembled material (Cung et al. 2013). Water contact angle analysis can characterize the binding of phage-displayed peptides or phage assembled materials onto target substrate, which could induce a change of water contact angle. Figure 2f shows the assembly of silver nanoparticles with multifunctional peptide which consists a binding motif screened from phage display (Swaminathan et al. 2014). The silver nanoparticles changed the water contact angle dramatically, which indicates the binding of phage-displayed peptides to target materials. Each of these characterization methods can provide unique information for the engineered phages or phage assembled materials, such as the dimension, binding strength, crystal structure, elemental composition, or surface property. The desired method for characterization can be determined according to the type of the material, such as M13 phage or a specific assembled material. Engineered phages for assembly of electronic materials The specific peptides displayed on the coat proteins of phage particles or the synthetic peptides with the sequence identified from phage display library have the capabilities for binding to target materials or synthesis of target materials. Here, we will summary the recent progress of the assembly of electronic materials with phage-displayed peptide. First, synthetic peptides can be designed for the assembly of electronic materials. Phage display biopanning can identify specific peptide sequences from a phage display library. The identified peptide can be linked to other peptides to form a multifunctional peptide, which has multiple functional binding or catalytic motifs. As shown in Figure 3a, a bifunctional grapheneAuNP peptide, with a binding motif to graphene and a binding motif to gold, was designed and

12

immobilized onto graphene nanosheet, and both the graphene binding peptide and Au binding peptide are identified from phage display technology. As shown in the figure, Au nanoparticles were captured onto graphene duo to the presence of bifunctional peptides. Besides, the bifunctional peptide can be designed to synthesis Au nanoparticles onto graphene too. Either of the peptides on pIII protein and the pVIII protein on the coat of phage surfaces can possess the capabilities for recognizing electronic materials or synthesizing electronic materials on the phage coats. The specific peptides on pIII proteins can be screened from phage display biopanning. Certain peptides on pVIII proteins, generally triglutamate (EEE) and tetraglutamate (EEEE) can be fused to the pVIII coat protein through recombinant DNA technology to nucleate different types of materials (Cung et al. 2013; Lee et al. 2009; Nam et al. 2006). A variety of nanomaterials have been investigated for being assembled on the coats of phage pVIII proteins, including CO3O4 (Ghosh et al. 2012; Nam et al. 2006), Au-CO3O4 (Nam et al. 2006), gold and silver noble metals and their alloy (Lee et al. 2010), and FePO4 (Lee et al. 2009; Moradi et al. 2015). Figure 3b shows the binding peptide motif on pIII protein and the catalytic motif on pVIII proteins (Lee et al. 2009). The peptide on pIII binds to carbon nanotubes, and in the mean time, the pVIII assemble the FePO4 onto the phage coats. Figure 3c shows both of the binding peptide motif and the catalytic motif on pVIII proteins, the Au binding motif binds Au nanoparticles onto the phage coats, the Co nucleating motif catalyzes the synthesis of Co materials onto phage coats (Nam et al. 2006), Figure 3d shows the binding of cations of Pb2+ on pVIII proteins due to the triglutamate peptide motif (Cung et al. 2013). Electronic devices are based on electronic materials. Assembly of electronic materials is of great importance for developing electronic devices to make the devices possess certain

13

properties. Phage particles can display specific peptides, which possess binding or catalytic abilities for assembly of new electronic materials. In addition, phage particles can display catalytic peptide motifs on the phage coat proteins to synthesize and assemble electronic materials on the phage coat proteins. By engineering phages, a variety of new electronic materials can be explored. Patterning engineered phages with electronic materials Microscale or nanoscale electronic materials can show enhanced special electronic properties compared to bulk materials. The spatial control of engineered phages can open up new opportunities in self-assembly, selective sensors, energy storage, and nano- and microelectronic devices. Further, the control of engineered phages can control the location of assembled hybrid materials. There are generally two main methods widely used in patterning of phages for electronic applications, one is by conventional fabrication, and the other is by transfer printing. The first method is by fabricating the electronic materials in nanoscale or microscale dimension, after that, the phage-displayed peptides recognize the patterned electronic materials, thus being patterned. Different fabrication methods for both microscale patterns and nanosale patterns have been widely studied, such as photolithography for micropatterns. Here, a typical nanoscale method is described for patterning phage-displayed peptides. Figure 4a shows the nanoscale patterning of graphene and the recognition of graphene with phage-displayed peptides (Cui et al. 2010a). The graphene nanostrips are fabricated by a combination of photolithography, electrochemical etching of Ni, dry etching to remove exposed graphene, and wet etching to remove Ni. Figure 4a shows AFM images Ni nanoribbons (left) and graphene nanoribbons (right), after incubation with graphene-binding phage-displayed peptide. As shown in the AFM images, no phage bind to Ni nanoribbonswas, as well as the background SiO2 substrate, and clear 14

binding of phages was shown in graphene nanoribbons. The precise patterning of target electronic materials and the effective selection of strong phage binders are necessary steps for successful patterning engineered phages with this method. The other method is using a micro/nanostructured stamp to print peptide-displaying phages onto an electronic material-based substrate or print phage assembled electronic materials to a target substrate. Wrinkle patterns (Chan and Crosby 2006; Evensen et al. 2009; Kim et al. 2011) were formed via inducing the surface instability of elastomer, which can function as a stamp for printing the phage-displayed peptides on a flat surface. The wrinkled PDMS can print SiO2-binding phage displayed peptides on to SiO2 surface, and the printed patterns are in accordance with the wrinkle patterns, as shown in Figure 4b (Swaminathan et al. 2014). Similarly, the PDMS stamp fabricated via photolithography and soft lithography has been used to pattern phage assembled which have assemble Co3O4, which has been used to construct pattened battery, as shown in Figure 4c (Ki et al. 2008). Successfully transferring phages from a patterned stamp to a target substrate is related to several factors, such as surface properties, forces between the stamp and substrate, etc. Due to these, it is a challenge to generate a large area of uniform phage patterns with the stamp method. Engineered phages for electronic sensors Biofunctionalized electronic sensors have been widely used for a variety of applications in medical diagnosis, defense, and environmental monitoring. The sensor is based on the immobilization of bioreceptor on electronic transducer materials. Peptides can function as the bioreceptors for sensing and can also function as linker for binding specific bioreceptor to the electrode surface. Phage displayed peptides have been used to select peptide sequences which can recognize either the electronic transducer or target analytes. 15

The immobilization of bioreceptors on electronic materials involves surface functionalization of electrodes. There are numerous types and structures of electronic materials, and for some of them, there are no existing methods for surface functionalization. Besides, for the existing methods, they can generally be applied to several types of electronic materials, instead of only one specific type. Further, among the existing methods, covalent functionalization can trigger symmetry breakage of the material surface bond, thereby altering its properties, and non-covalent chemical modification strategies may be limited in scope of applicability. Thus, a general method for the functionalization of electronic materials with specific binding motifs while retaining the excellent properties of electronic materials is thus highly desired. Phage display can be used to select specific peptide sequences for recognizing the sensor electrode materials, and the screened peptide sequence can be used as a linker for immobilizing other bioreceptors on the electrode. Multifunctional peptides with both the binding motifs to the sensor surface and the binding motif to the analyte can be synthesized. By immobilizing the multifunctional peptides on sensor electrodes, in the presence of target analyte, the analyte can bind to the multifunctional peptide on the sensor surface to generate a signal response. The phage displayed peptide has been successfully used to select specific linkers for developing graphene based biosensors (Cui et al. 2010a), carbon nanotube based biosensors (Kuang et al. 2010), etc. Figure 5a shows the detection of TNT with a graphene field-effect-transistor (GFET) immobilized with a bifunctional peptide (Cui et al. 2010a), which consists of a graphene binding peptide identified from a phage display library, and a TNT-binding peptide identified via millions of years of evolution. As shown in in the figure, the bifuncitonal peptide functionalized GFET exhibits a significant signal response for the detection of 12 ppb TNT.

16

Phage display can be used to identify specific peptides for recognizing target analytes for the sensor development. The pure specific peptides without the phage particles can be synthesized and immobilized on electrode surfaces through conventional surface chemistry. A variety of sensors have been constructed with this method for detection of different analytes, including troponin (Wu et al. 2010), bisphenol-A (Yang et al. 2014), alanine aminotransferase (Wu et al. 2011), etc. Figure 5b shows the peptide-functionalized electrode for the detection of troponin with electrochemical impedance spectroscopy (EIS) (Wu et al. 2010). The peptide identified for binding to troponin is immobilized on a gold surface via cysteine amino acid added to the C-terminus of the peptide. For the EIS measurements, the sensitivity for the detection of troponin was 0.030 normalized impedance/(μg/mL) and the limit of detection (LOD) was 0.34 μg/ml. Further, phage particles are used widely as the bioreceptors in the sensor constructions. Engineered phages can display different specific peptides or proteins, which can bind to target analytes, and several types of specific phages have been screened and immobilized on electrodes for the construction of bioelectronics sensors for several analytes, including anti-M13 antibody (Arter et al. 2010), human phosphatase of regenerating liver-3 (Jia et al. 2007), cells (Han et al. 2016; Jia et al. 2007), etc. Figure 5c shows the M13 phage incorporated poly (3,4ethylenedioxythiophene) (PEDOT) nanowires sensor (Arter et al. 2010). The sensor shows the signal response towards the analyte, which is the antibody. The resultant arrays of virus-PEDOT nanowires provide a new approach for sensor construction. Potentially by engineering the peptides displayed on the coat of M13 phage, the M13 phage incorporated electronic sensors can be used for a variety of other applications too.

17

The above three different approaches provide guidance for developing new specific sensors. There are a large amount of analytes, which do not have existing specific bioreceptors, and phage display could be an effective tool for selecting specific bioreceptors – peptides, for binding to these analytes to develop selective sensors. The selected peptides can be immobilized on the electrode surfaces as “synthetic peptides” or “displayed peptides on phage particles”. In addition, there are a large amount of electrode materials, which can be used as sensing electrodes but do not have mature or existing surface functionalization methods to immobilize bioreceptors on electrodes. Phage display can be used to select specific linkers, which are the peptide linkers. These linkers can be conjugated to the bioreceptors for analytes, and the bioreceptors can be immobilized on electrode surfaces through immobilizing the linkers. The selection of specific peptides for developing sensors requires comprehensive phage display biopanning processes, and to date, there are only several types of bioelectronics sensors have been developed based on these approaches. By using different combinations of electronic materials as the sensing transducers and peptides identified from phage display as bioerceptors, it is expected that a variety of other specific sensors can be developed to detect analytes for a wide range of applications in the future with the above approaches. Engineered phages for energy devices A certain number of the negatively charged amino-acid glutamate (E), generally from 1E to 4E, have been studied to fused into the pVIII coat proteins of the M13 phage particles, to enable the use of phages in the construction of electronic devices. M13 phage has a length of 900 nm and a diameter of 6.5 nm, and due to the high aspect ratio of phage particle and the unique properties of the peptides displayed on the phage coat proteins, phage particles have been studied as templates for assembly of different electronic materials onto phages particles to form high-

18

aspect-ratio nanowires for the construction of electronic devices under a mild, low temperature condition, including battery, piezoelectric device, solar cell, and fuel cell. Besides, through recombinant DNA, M13 phages themselves can exhibit specific piezoelectric electronic properties, which have enabled phages to be used directly as a piezoelectric device. Battery electrodes can store and release electrical energy by insertion and extraction of ions and electrons, and controlling nanostructures and types of materials of the electrodes is a critical process to enhance the battery performance. M13 phage-assembled materials can be used as the either anodes and cathodes in the battery systems by assembling different types of electronic materials on the coat proteins. Several materials have been assembled on phages as anodes of batteries, including Au and Ag noble metals and their alloy nanowires (Lee et al. 2010), Co3O4 (Ghosh et al. 2012; Nam et al. 2006), and Au-CO3O4 (Nam et al. 2006). Several materials have been assembled as cathodes of batteries, including FePO4 (Lee et al. 2009; Moradi et al. 2015), CoMn2O4 (Oh et al. 2014), MnCo2O4 (Oh et al. 2014), CoMn2O4 (Oh et al. 2014), and BiO0.5F2 (Oh et al. 2012), as shown in Figure 6a. Piezoelectric materials, which can convert mechanical energy into electrical energy, have been used for energy harvesting (Hu et al. 2016a; Wang et al. 2016a), sensors (Karaseva et al. 2016; Lenardo et al. 2016), and actuators (Chattaraj and Ganguli 2016; Shen et al. 2016), etc. Two methods have been developed to construct piezoelectric devices using phage-based piezoelectric materials. The first method is based assembly of piezoelectric materials on phage particles. As shown in Figure 6b, inorganic piezoelectric materials, PZT, have been synthesized with M13 phages as the templates (Cung et al. 2013), which control the composition and crystallinity in a rational approach. The second method is based on using recombinant DNA to display certain peptides on phage coat proteins to enable the phage particles themselves to

19

exhibit specific piezoelectric properties. As shown in Figure 6c, the genetically engineered M13 phages show specific piezoelectric properties and can be used for the construction of a piezoelectric energy device (Lee et al. 2012). Similarly, M13 phages can be used as templates to assemble other inorganic materials on phage coats for dye-sensitized solar cell (Chen et al. 2013) and hydrogen fuel cell (Neltner et al. 2010). As shown in Figure 6d, M13 phages can bind Au nanoparticles on coat proteins, which can further be encapsulated in TiO2 to produce a nanowire-based photoanode, and this can improve the electron transport and light harvesting for the dye-sensitized solar cell (Chen et al. 2013). Besides, M13 phages can assemble nickel, rhodium, and ceria as the catalysts to improve the activity and stability of catalysts for hydrogen fuel cell (Neltner et al. 2010). Using engineered phages to assemble new materials provide a new approach for developing bio-inspired electronic devices for a variety of applications. As described above, several types of electronic materials have been assembled on phage particles to enable the construction of battery, piezoelectric device, solar cell, and fuel cell based on phages. Though there are still significant limitations for the performance of these electronic devices, such as capacity retention upon cycling for battery, the phage assembly approach provides an environmentally benign, low temperature method for the construction of new electronic devices. There are a large amount of other electronic materials which have not been studied based on the assembly on phage particles, but have the potential to generate new types of electronic devices with the use of engineered phages. In addition, through recombinant DNA, phage particles can display certain electronic properties themselves, which potentially provide a new approach for generating other types of electronic devices. To date, only a few types of electronic devices have been studied based on engineered phages. It is expected that more new types of electronic

20

materials and electronic devices can be developed based on the engineered phages in the future, such as transistors, capacitors, etc. Conclusions and Future Perspectives Phages have been traditionally studied in biological sciences for recognizing a variety of biological molecules. Recently, there have been certain attempts for studying the engineering aspects of phages in electronics, including the electronic materials and the further construction of electronic devices. These devices are functionalized with or made of engineered phages, including sensors, batteries, piezoelectric devices, a solar cell, and a fuel cell. These introduce new opportunities in electronics. The catalysts for these exciting advances have been (1) the identification of peptides displayed on phage coats which have binding or catalytic abilities for the construction of hybrid electronic system, (2) the fusion of new peptides with phage coat proteins which can result in binding or nucleation of novel electronic materials, and (3) the fusion of peptide motifs with phage coat proteins to enable the phage particle to possess certain electronic properties. The field is nascent, and to date, there are only several types of electronic devices that have been constructed based on engineered phages. Through these approaches, a variety of other novel materials with new properties can be constructed in the future, and further advances in developing new electronic devices can be made for a wide range of applications ranging from sensing to energy conversion. Acknowledgements The author acknowledges University of Cincinnati for the support of this work.

21

References Amiri, M., Amali, E., Nematollahzadeh, A., Salehniya, H., 2016. Poly-dopamine films: Voltammetric sensor for pH monitoring. Sensor. Actuat. B-Chem. 228, 53-58. Arter, J.A., Taggart, D.K., McIntire, T.M., Penner, R.M., Weiss, G.A., 2010. Virus-PEDOT nanowires for biosensing. Nano Lett. 10(12), 4858-4862. Azam, S., Khan, S.A., Minar, J., Goumri-Said, S., 2015. Exploring the electronic structure and optical properties of new inorganic luminescent materials Ba(Si,Al)5(O,N)8 compounds for light-emitting diodes devices. Curr. Appl. Phys. 15(10), 1160-1167. Benchirouf, A., Müller, C., Kanoun, O., 2016. Electromechanical Behavior of Chemically Reduced Graphene Oxide and Multi-walled Carbon Nanotube Hybrid Material. Nanoscale Res. Lett. 11(1), 1-7. Boukamp, B.A., Pham, M.T.N., Blank, D.H.A., Bouwmeester, H.J.M., 2004. Ionic and electronic conductivity in lead-zirconate-titanate (PZT). Solid State Ionics 170(3-4), 239-254. Chan, E.P., Crosby, A.J., 2006. Spontaneous formation of stable aligned wrinkling patterns. Soft Matter 2(4), 324-328. Chan, P., Phan, T., Kao, M.C., Dolan, C., Tok, J.B.H., 2006. Generating short peptidic ligands for silver nanowires from phage display random libraries. Bioorg. Med. Chem. Lett. 16(20), 5261-5264. Chattaraj, N., Ganguli, R., 2016. Electromechanical analysis of piezoelectric bimorph actuator in static state considering the nonlinearity at high electric field. Mech. Adv. Mater. Struc. 23(7), 802-810. Chen, H., Su, X., Neoh, K.G., Choe, W.S., 2006. QCM-D analysis of binding mechanism of phage particles displaying a constrained heptapeptide with specific affinity to SiO2 and TiO 2. Anal. Chem. 78(14), 4872-4879. Chen, P.Y., Dang, X., Klug, M.T., Qi, J., Dorval Courchesne, N.M., Burpo, F.J., Fang, N., Hammond, P.T., Belcher, A.M., 2013. Versatile three-dimensional virus-based template for dyesensitized solar cells with improved electron transport and light harvesting. ACS Nano 7(8), 6563-6574. Cui, Y., Kim, S.N., Jones, S.E., Wissler, L.L., Naik, R.R., McAlpine, M.C., 2010a. Chemical Functionalization of Graphene Enabled by Phage Displayed Peptides. Nano Lett. 10(11), 45594565. Cui, Y., Kim, S.N., Naik, R.R., McAlpine, M.C., 2012. Biomimetic peptide nanosensors. Acc. Chem. Res. 45(5), 696-704. Cui, Y., Pattabiraman, A., Lisko, B., Collins, S.C., McAlpine, M.C., 2010b. Recognition of Patterned Molecular Ink with Phage Displayed Peptides. J. Am. Chem. Soc. 132(4), 1204-1205. Cung, K., Han, B.J., Nguyen, T.D., Mao, S., Yeh, Y.W., Xu, S., Naik, R.R., Poirier, G., Yao, N., Purohit, P.K., McAlpine, M.C., 2013. Biotemplated synthesis of PZT nanowires. Nano Lett. 13(12), 6197-6202. Donthu, S., Pan, Z.X., Myers, B., Shekhawat, G., Wu, N.G., Dravid, V., 2005. Facile scheme for fabricating solid-state nanostructures using e-beam lithography and solution precursors. Nano Lett. 5(9), 1710-1715. Estephan, E., Larroque, C., Cloitre, T., Cuisinier, F.J.G., Gergely, C., 2008. Specific peptide for functionalization of GaN. In: Popp, J., Drexler, W., Tuchin, V.V., Matthews, D.L. (Eds.), Biophotonics: Photonic Solutions for Better Health Care.

22

Estephan, E., Saab, M.-b., Larroque, C., Martin, M., Olsson, F., Lourdudoss, S., Gergely, C., 2009. Peptides for functionalization of InP semiconductors. J. Colloid Interface Sci. 337(2), 358363. Estephan, E., Saab, M.-B., Martin, M., Larroque, C., Cuisinier, F.J.G., Briot, O., Ruffenach, S., Moret, M., Gergely, C., 2011a. Phages recognizing the Indium Nitride semiconductor surface via their peptides. J. Pept. Sci. 17(2), 143-147. Estephan, E., Saab, M.B., Agarwal, V., Cuisinier, F.J.G., Larroque, C., Gergely, C., 2011b. Peptides for the biofunctionalization of silicon for use in optical sensing with porous silicon microcavities. Adv. Funct. Mater. 21(11), 2003-2011. Evensen, H.T., Jiang, H., Gotrik, K.W., Denes, F., Carpick, R.W., 2009. Transformations in Wrinkle Patterns: Cooperation between Nanoscale Cross-Linked Surface Layers and the Submicrometer Bulk in Wafer-Spun, Plasma-Treated Polydimethylsiloxane. Nano Lett. 9(8), 2884-2890. Fang, Y., Wu, Q., Dickerson, M.B., Cai, Y., Shian, S., Berrigan, J.D., Poulsen, N., Kroger, N., Sandhage, K.H., 2009. Protein-mediated layer-by-layer syntheses of freestanding microscale titania structures with biologically assembled 3-D morphologies. Chem. Mater. 21(24), 57045710. Ghosh, A., Guo, J., Brown, A.D., Royston, E., Wang, C., Kofinas, P., Culver, J.N., 2012. Virusassembled flexible electrode-electrolyte interfaces for enhanced polymer-based battery applications. J. Nanomater. 2012. Golec, P., Karczewska-Golec, J., Loś, M., Wȩ grzyn, G., 2012. Novel ZnO-Binding peptides obtained by the screening of a phage display peptide library. J. Nanopart. Res. 14(11). Ha, Y.G., Everaerts, K., Hersam, M.C., Marks, T.J., 2014. Hybrid gate dielectric materials for unconventional electronic circuitry. Acc. Chem. Res. 47(4), 1019-1028. Han, L., Liu, P., Petrenko, V.A., Liu, A.H., 2016. A label-free electrochemical impedance cytosensor based on specific peptide-fused phage selected from landscape phage library. Scientific Reports 6. Heinz, H., Farmer, B.L., Pandey, R.B., Slocik, J.M., Patnaik, S.S., Pachter, R., Naik, R.R., 2009. Nature of molecular interactions of peptides with gold, palladium, and Pd-Au bimetal surfaces in aqueous solution. J. Am. Chem. Soc. 131(28), 9704-9714. Horiuchi, S., Fujita, T., Hayakawa, T., Nakao, Y., 2003. Micropatterning of metal nanoparticles via UV photolithography. Adv. Mater. 15(17), 1449-1452. Hu, C., Cheng, L., Wang, Z., Zheng, Y., Bai, S., Qin, Y., 2016a. A Transparent Antipeep Piezoelectric Nanogenerator to Harvest Tapping Energy on Screen. Small. Hu, Y., Lian, H., Zu, L., Jiang, Y., Hu, Z., Li, Y., Shen, S., Cui, X., Liu, Y., 2016b. Durable electromechanical actuator based on graphene oxide with in situ reduced graphene oxide electrodes. J Mater Sci 51(3), 1376-1381. Jia, Y., Qin, M., Zhang, H., Niu, W., Li, X., Wang, L., Li, X., Bai, Y., Cao, Y., Feng, X., 2007. Label-free biosensor: A novel phage-modified Light Addressable Potentiometric Sensor system for cancer cell monitoring. Biosens. Bioelectron. 22(12), 3261-3266. Kahraman, A., Yilmaz, E., Kaya, S., Aktag, A., 2015. Effects of packing materials on the sensitivity of RadFET with HfO2 gate dielectric for electron and photon sources. Radiat Eff. Defects Solids 170(10), 832-844. Karaseva, N., Ermolaeva, T., Mizaikoff, B., 2016. Piezoelectric sensors using molecularly imprinted nanospheres for the detection of antibiotics. Sensor. Actuat. B-Chem. 225, 199-208.

23

Ki, T.N., Wartena, R., Yoo, P.J., Liau, F.W., Yun, J.L., Chiang, Y.M., Hammond, P.T., Belcher, A.M., 2008. Stamped microbattery electrodes based on self-assembled M13 viruses. Proc. Natl. Acad. Sci. USA 105(45), 17227-17231. Kim, J., Choi, S.W., Lee, J.H., Chung, Y., Byun, Y.T., 2016. Gas sensing properties of defectinduced single-walled carbon nanotubes. Sensor. Actuat. B-Chem. 228, 688-692. Kim, P., Abkarian, M., Stone, H.A., 2011. Hierarchical folding of elastic membranes under biaxial compressive stress. Nat. Mater. 10(12), 952-957. Kuang, Z., Kim, S.N., Crookes-Goodson, W.J., Farmer, B.L., Naik, R.R., 2010. Biomimetic chemosensor: Designing peptide recognition elements for surface functionalization of carbon nanotube field effect transistors. ACS Nano 4(1), 452-458. Lan, C., Zhao, S., Xu, T., Ma, J., Hayase, S., Ma, T., 2016. Investigation on structures, band gaps, and electronic structures of lead free La2NiMnO6 double perovskite materials for potential application of solar cell. J. Alloys Compd. 655, 208-214. Lee, B.Y., Zhang, J., Zueger, C., Chung, W.J., Yoo, S.Y., Wang, E., Meyer, J., Ramesh, R., Lee, S.W., 2012. Virus-based piezoelectric energy generation. Nat. Nanotechnol. 7(6), 351-356. Lee, S., Hong, J.Y., Jang, J., 2015. A Comparative Study on Optical, Electrical, and Mechanical Properties of Conducting Polymer-Based Electrodes. Small 11(41), 5498-5504. Lee, Y.J., Lee, Y., Oh, D., Chen, T., Ceder, G., Belcher, A.M., 2010. Biologically activated noble metal alloys at the nanoscale: For lithium ion battery anodes. Nano Lett. 10(7), 2433-2440. Lee, Y.J., Yi, H., Kim, W.J., Kang, K., Yun, D.S., Strano, M.S., Ceder, G., Belcher, A.M., 2009. Fabricating genetically engineered high-power lithium-ion batteries using multiple virus genes. Science 324(5930), 1051-1055. Lenardo, B., Li, Y., Manalaysay, A., Morad, J., Payne, C., Stephenson, S., Szydagis, M., Tripathi, M., 2016. Position reconstruction of bubble formation in liquid nitrogen using piezoelectric sensors. J. Instrum. 11(1). Li, Z., Uzawa, T., Zhao, H., Luo, S.C., Yu, H.H., Kobatake, E., Ito, Y., 2014. In vitro selection of peptide aptamers using a ribosome display for a conducting polymer. J. Biosci. Bioeng. 117(4), 501-503. Ma, H., Sun, J., Zhang, Y., Bian, C., Xia, S., Zhen, T., 2016. Label-free immunosensor based on one-step electrodeposition of chitosan-gold nanoparticles biocompatible film on Au microelectrode for determination of aflatoxin B1 in maize. Biosens. Bioelectron. 80, 222-229. Mahony, J., McDonnell, B., Casey, E., Van Sinderen, D., 2016. Phage-Host Interactions of Cheese-Making Lactic Acid Bacteria. Annual Review of Food Science and Technology 7, 267285. Mao, C., Flynn, C.E., Hayhurst, A., Sweeney, R., Qi, J., Georgiou, G., Iverson, B., Belcher, A.M., 2003. Viral assembly of oriented quantum dot nanowires. Proc. Natl. Acad. Sci. USA 100(12), 6946-6951. Moradi, M., Li, Z., Qi, J., Xing, W., Xiang, K., Chiang, Y.M., Belcher, A.M., 2015. Improving the capacity of sodium ion battery using a virus-templated nanostructured composite cathode. Nano Lett. 15(5), 2917-2921. Motlagh, A.M., Bhattacharjee, A.S., Goel, R., 2016. Biofilm control with natural and genetically-modified phages. World Journal of Microbiology and Biotechnology 32(4), 1-10. Mueller, M., Baik, S., Jeon, H., Kim, Y., Kim, J., Kim, Y.J., 2015. Directed synthesis of bioinorganic vanadium oxide composites using genetically modified filamentous phage. Appl. Surf. Sci. 337, 12-18.

24

Nam, K.T., Kim, D.W., Yoo, P.J., Chiang, C.Y., Meethong, N., Hammond, P.T., Chiang, Y.M., Belcher, A.M., 2006. Virus-enabled synthesis and assembly of nanowires for lithium ion battery electrodes. Science 312(5775), 885-888. Neltner, B., Peddie, B., Xu, A., Doenlen, W., Durand, K., Yun, D.S., Speakman, S., Peterson, A., Belcher, A., 2010. Production of hydrogen using nanocrystalline protein-templated catalysts on M13 phage. ACS Nano 4(6), 3227-3235. Nergiz, S.Z., Slocik, J.M., Naik, R.R., Singamaneni, S., 2013. Surface defect sites facilitate fibrillation: An insight into adsorption of gold-binding peptides on Au(111). Phys. Chem. Chem. Phys. 15(28), 11629-11633. Nickels, J.D., Schmidt, C.E., 2013. Surface modification of the conducting polymer, polypyrrole, via affinity peptide. J. Biomed. Mater. Res. Part B 101 A(5), 1464-1471. Nobeshima, T., Nakamura, K., Kobayashi, N., 2013. Electrochemical materials for novel light emitting device and dual mode display. J. Photopolym. Sci. Tec. 26(3), 397-402. Oh, D., Dang, X., Yi, H., Allen, M.A., Xu, K., Lee, Y.J., Belcher, A.M., 2012. Graphene sheets stabilized on genetically engineered M13 viral templates as conducting frameworks for hybrid energy-storage materials. Small 8(7), 1006-1011. Oh, D., Qi, J., Han, B., Zhang, G., Carney, T.J., Ohmura, J., Zhang, Y., Shao-Horn, Y., Belcher, A.M., 2014. M13 virus-directed synthesis of nanostructured metal oxides for lithium-oxygen batteries. Nano Lett. 14(8), 4837-4845. Pławińska, Z., Michalska, A., Maksymiuk, K., 2016. Optimization of capacitance of conducting polymer solid contact in ion-selective electrodes. Electrochim. Acta 187, 397-405. Qin, W., Hou, J., Bonnell, D.A., 2015. Effect of interface atomic structure on the electronic properties of nano-sized metal-oxide interfaces. Nano Lett. 15(1), 211-217. Rinaldi, A.L., Carballo, R., 2016. Impedimetric non-enzymatic glucose sensor based on nickel hydroxide thin film onto gold electrode. Sensor. Actuat. B-Chem. 228, 43-52. Sanghvi, A.B., Miller, K.P.H., Belcher, A.M., Schmidt, C.E., 2005. Biomaterials functionalization using a novel peptide that selectively binds to a conducting polymer. Nat. Mater. 4(6), 496-502. Sarikaya, M., Tamerler, C., Jen, A.K.Y., Schulten, K., Baneyx, F., 2003. Molecular biomimetics: nanotechnology through biology. Nature Materials 2(9), 577-585. Sattar, S., Bennett, N.J., Wen, W.X., Guthrie, J.M., Blackwell, L.F., Conway, J.F., Rakonjac, J., 2015. Ff-nano, short functionalized nanorods derived from Ff (f1, fd or M13) filamentous bacteriophage. Front. Microboil. 6(MAR). Schwierz, F., Pezoldt, J., Granzner, R., 2015. Two-dimensional materials and their prospects in transistor electronics. Nanoscale 7(18), 8261-8283. Seo, M.H., Lee, J.H., Kim, M.S., Chae, H.K., Myung, H., 2006. Selection and characterization of peptides specifically binding to TiO2 nanoparticles. J. Microbiol. Biotechn. 16(2), 303-307. Shen, H.S., Chen, X., Huang, X.L., 2016. Nonlinear bending and thermal postbuckling of functionally graded fiber reinforced composite laminated beams with piezoelectric fiber reinforced composite actuators. Compos. Part B-Eng. 90, 326-335. Shi, M., Shi, Y., Zuo, R., Xu, Y., Peng, X., Li, D., Xie, L., 2015. Microstructure, ferroelectric and dielectric proprieties of Bi4Ti3O12 materials prepared by two methods. J Mater Sci Mater Electron, 1-7. Swaminathan, S., Bullough, M., Li, Q., Zhou, A., Cui, Y., 2014. Non-lithographic patterning of phage-displayed peptides with wrinkled elastomers. J. R. Soc. Interface 11(91).

25

Swaminathan, S., Cui, Y., 2013. Recognition of epoxy with phage displayed peptides. Mater. Sci. Eng., C 33(5), 3082-3084. Takagi, K., Nagase, T., Kobayashi, T., Naito, H., 2016. Determination of deep trapping lifetime in organic semiconductors using impedance spectroscopy. Appl. Phys. Lett. 108(5). Tomer, V.K., Devi, S., Malik, R., Nehra, S.P., Duhan, S., 2016. Highly sensitive and selective volatile organic amine (VOA) sensors using mesoporous WO3-SnO2 nanohybrids. Sensor. Actuat. A-Phys. 229, 321-330. Wang, C., Dong, H., Hu, W., Liu, Y., Zhu, D., 2012. Semiconducting π-conjugated systems in field-effect transistors: A material odyssey of organic electronics. Chem. Rev. 112(4), 22082267. Wang, X., Liang, X., Hao, Z., Du, H., Zhang, N., Qian, M., 2016a. Comparison of electromagnetic and piezoelectric vibration energy harvesters with different interface circuits. Mech. Syst. Signal PR. 72-73, 906-924. Wang, X., Zhang, G.Z., Xu, Y., Gan, X.W., Chen, C., Wang, Z., Wang, Y., Wang, J.L., Wang, T., Wu, H., Liu, C., 2016b. Leakage Current Mechanism of InN-Based Metal-InsulatorSemiconductor Structures with Al2O3 as Dielectric Layers. Nanoscale Res. Lett. 11(1), 1-5. Wei, Z., Maeda, Y., Matsui, H., 2011. Discovery of catalytic peptides for inorganic nanocrystal synthesis by a combinatorial phage display approach. Angew. Chem. Int. Edit. 50(45), 1058510588. Whaley, S.R., English, D.S., Hu, E.L., Barbara, P.F., Belcher, A.M., 2000. Selection of peptides with semiconductor binding specificity for directed nanocrystal assembly. Nature 405(6787), 665-668. Wu, G., Yin, P., Dai, R., Wang, M., Chen, H., Li, H., Liu, D., 2012. Microcapsule-based materials for electrophoretic displays. J. Mater. Res. 27(4), 653-662. Wu, J., Cropek, D.M., West, A.C., Banta, S., 2010. Development of a troponin i biosensor using a peptide obtained through phage display. Anal. Chem. 82(19), 8235-8243. Wu, J., Park, J.P., Dooley, K., Cropek, D.M., West, A.C., Banta, S., 2011. Rapid development of new protein biosensors utilizing peptides obtained via phage display. PLoS ONE 6(10). Wu, Y., Farmer, D.B., Xia, F., Avouris, P., 2013. Graphene electronics: Materials, devices, and circuits. Proceedings of the IEEE 101(7), 1620-1637. Yalovega, G.E., Shmatko, V.A., Funik, A.O., Brzhezinskaya, M.M., 2016. Morphology, atomic and electronic structure of metal oxide (CuOx, SnOx) nanocomposites and thin films. International Conference on Physics, Mechanics of New Materials and Their Applications, PHENMA 2015 175, 299-315. Yang, B., Shao, M., Keum, J., Geohegan, D., Xiao, K., 2016. Nanophase engineering of organic semiconductor-based solar cells. Springer Series in Materials Science, pp. 197-228. Springer Verlag. Yang, J., Kim, S.E., Cho, M., Yoo, I.K., Choe, W.S., Lee, Y., 2014. Highly sensitive and selective determination of bisphenol-A using peptide-modified gold electrode. Biosens. Bioelectron. 61, 38-44. Yoshida, H., Yoshizaki, K., 2015. Electron affinities of organic materials used for organic lightemitting diodes: A low-energy inverse photoemission study. Org. Electron. 20, 24-30. Yu, T., Gong, Y., Lu, T., Wei, L., Li, Y., Mu, Y., Chen, Y., Liao, K., 2012. Recognition of carbon nanotube chirality by phage display. RSC Advances 2(4), 1466-1476.

26

Zarhri, Z., Houmad, M., Ziat, Y., El Rhazouani, O., Slassi, A., Benyoussef, A., El Kenz, A., 2016. Ab-initio study of magnetism behavior in TiO2 semiconductor with structural defects. J. Magn. Magn. Mater. 406, 212-216. Zhang, F., Yang, X., Cheng, M., Wang, W., Sun, L., 2016. Boosting the efficiency and the stability of low cost perovskite solar cells by using CuPc nanorods as hole transport material and carbon as counter electrode. Nano Energy 20, 108-116. Zhao, A., Tohidkia, M.R., Siegel, D.L., Coukos, G., Omidi, Y., 2016. Phage antibody display libraries: A powerful antibody discovery platform for immunotherapy. Critical Reviews in Biotechnology 36(2), 276-289. Zhou, J., Mulle, M., Zhang, Y., Xu, X., Li, E.Q., Han, F., Thoroddsen, S.T., Lubineau, G., 2016. High-ampacity conductive polymer microfibers as fast response wearable heaters and electromechanical actuators. J. Mater. Chem. C 4(6), 1238-1249. Zuo, R., Örnek, D., Wood, T.K., 2005. Aluminum- and mild steel-binding peptides from phage display. Appl. Microbiol. Biotechnol. 68(4), 505-509.

27

Figure Captions Figure 1. Selection of phage displayed peptides, (a) multifunctional M13 phage (Lee et al. 2009), (b) selection of peptides for binding to target materials (Sarikaya et al. 2003), and (c) selection of peptides for catalyzing the synthesis of target material (Wei et al. 2011). Figure 2. Characterization of phage displayed peptides with (a) AFM (Cui et al. 2010a), (b) circular dichroism (Kuang et al. 2010), (c) SEM (Swaminathan et al. 2014), (d) TEM (Lee et al. 2009), (e) XRD (Cung et al. 2013), and (f) contact angle (Swaminathan et al. 2014). Figure 3. Assembly of electronic materials, (a) binding of Au nanoparticles on graphene with synthetic bifunctional peptides (Cui et al. 2010a), (b) binding of carbon nanotubes with peptide on pIII protein and synthesis of α-FePO4 with peptide on pVIII proteins (Lee et al. 2009), (c) binding of Au nanoparticles and synthesis of Co nanoparticles with peptides on pVIII proteins (Nam et al. 2006), (e) Binding of Pb2+ cations with peptide on pVIII proteins (Cung et al. 2013). Figure 4. Patterning of phage displayed peptides with (a) nanopatterning of phage displayed peptides (Cui et al. 2010a), (b) micropatterning of phage displayed peptides (Swaminathan et al. 2014), and (c) micropatterning of batteries (Ki et al. 2008). Figure 5. Electronic sensors, (a) phage displayed peptides recognizing electronic materials (Cui et al. 2010a), (b) phage displayed peptide recognizing detection analyte (Wu et al. 2010), and (c) phages on electronic devices (Arter et al. 2010). Figure 6. Phage-based energy devices, (a) phage-assembled material for battery cathode (Lee et al. 2009), (b) phage assembled piezoelectric material (Cung et al. 2013), (c) piezoelectric phage (Lee et al. 2012), and (d) phage-assembled material for photoanode in solar cell (Chen et al. 2013).

28

Table 1. Selection or expression of peptides on phages for electronics.

Approaches

Binding peptide on pIII coat protein of M13 phage identified by phage display biopanning

Catalytic peptide on pIII coat protein of M13 phage identified by phage display biopanning

Electronic Materials

References

Metals

Ag, Au, Pd, TiO2, ZnS, CdS, Al, steel, etc.

Chan et al. 2006, Nergiz et al. 2013, Heinz et al. 2009, Chen et al. 2006, Seo et al. 2006, Mao et al. 2003, Mao et al. 2003, Zuo et al. 2005, Zuo et al. 2005

Semiconductors

Si, SiO2, ZnO, InP, GaN, InN, etc.

Estephan et al. 2011b, Chen et al. 2006, Golec et al. 2012, Estephan et al. 2009, Estephan et al. 2008, Estephan et al. 2011a

Polymers

polypyrrole, chlorone-doped polypyrrole, poly(3hexylthiophene2,5-diyl), etc.

Nickels and Schmidt 2013, Sanghvi et al. 2005, Li et al. 2014

Nanomaterials

Carbon nanotube, graphene, etc.

Yu et al. 2012, Cui et al. 2010a

ZnO

Wei et al. 2011

1E to 4E on pVIII coat proteinsof M13 phage using recombinant DNA technique for assembly of electronic materials

Au and Ag noble metals and their alloy nanowires, Co3O4, Au-CO3O4, FePO4, CoMn2O4, MnCo2O4, CoMn2O4, BiO0.5F2, PZT, Au, nickel, rhodium, and ceria, etc.

1E to 4E on pVIII coat proteins of M13 phage using recombinant DNA technique to enable phage with piezoelectric property

M13 phage

29

Chen et al. 2013, Lee et al. 2010, Ghosh et al. 2012, Nam et al. 2006, Nam et al. 2006, Lee et al. 2009, Moradi et al. 2015, Oh et al. 2014, Oh et al. 2012, Cung et al. 2013, Chen et al. 2013, Neltner et al. 2010

Lee et al. 2012

Table 2. Typical characterization methods for engineered phages or phage assembled materials. Typical Characterization Techniques

Information

References

Fluorescent Immunoassay

Image of peptide-displaying phages onto electronic materials

Swaminathan and Cui 2013

AFM

Image of peptide-displaying phages onto electronic materials; or image of assembled materials via engineered phages or synthetic peptides

Cui et al. 2010a

Circular Dichroism

Structure of the peptides to determine the contents and fractions of certain structures

Kuang et al. 2010

SEM

Image of assembled materials via engineered phages or synthetic peptides

Cui et al. 2010a; Swaminathan et al. 2014

TEM

Image of assembled materials via engineered phages or synthetic peptides

Mueller et al. 2015

XRD

Crystal structure of assembled materials via engineered phages or synthetic peptides

Cung et al. 2013

EDX

Elemental composition of assembled material via engineered phages or synthetic peptides

Cung et al. 2013

Contact Angle

Surface properties due to the binding of phagedisplayed peptides, synthetic peptides, or assembled materials

Swaminathan et al. 2014

30

Highlights  The review focuses on the fundamentals and applications of engineered phages in electronics.  How to select or engineer phages for specific electronic materials? How are the engineered phages characterized? How to assemble materials with engineered phages? How are the engineered phages micro or nanopatterned? What are the strategies for constructing specific sensors or energy devices with engineered phages?

31

FIGURES

32

33

34

35

36

37