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Nanomachine-Related Topics
CHAPTER TWENTY
Nanomachine-Related Topics Contents 20.1 Molecular Drill for Opening Cell Membranes 20.2 Antibody-Powered DNA Nanomachines 20.3 Vesicle Origami: Cuboid Phospholipid Vesicles 20.4 Nanoswimmers to the Brain 20.5 Hydrophobic Phage-Mimicking Membrane Active Antimicrobials References
233 234 235 235 236 237
20.1 MOLECULAR DRILL FOR OPENING CELL MEMBRANES Beyond the more common chemical delivery strategies, there are several physical techniques to open the lipid bilayers of cellular membranes. These include electric and magnetic fields, temperature, ultrasonic, or light to put compounds into cells, to release molecular species from cells, or to induce selective cell death (apoptosis). More recently, molecular motors and switches that can change their conformation in a controlled way in response to external stimuli have been used to produce mechanical actions on tissue for biomedical applications (Barber et al., 2016). Garcı´a-Lo´pez et al. (2017) demonstrated that molecular machines can drill through cellular lipid bilayers using the molecular-scale nanomechanical action. After the adsorption of the molecular motors on lipid bilayers and activation of the motors using ultraviolet light, holes are drilled in the cell membranes. Garcı´a-Lo´pez et al. designed molecular motors (see Fig. 20.1.1) and complementary experimental protocols that use nanomechanical action. They also showed that, by changing functional addends (R), the motors can target specific cell surface sites. After the in vitro applications, they expect that molecular machines could also be used in vivo, especially as their design progresses to allow two-photon, nearinfrared, and radio-frequency activation. Biochemistry for Materials Science https://doi.org/10.1016/B978-0-12-817054-0.00020-5
© 2019 Elsevier Inc. All rights reserved.
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Biochemistry for Materials Science
Fig. 20.1.1 Molecular drill for opening cell membranes.
20.2 ANTIBODY-POWERED DNA NANOMACHINES Ranallo et al. (2017) reported an antibody-powered DNA-based nanomachine that can reversibly load and release a molecular cargo on binding to a specific antibody. A DNA strand labeled with two antigens can load a nucleic acid strand through a clamp-like triplex-forming mechanism that uses Hoogsteen-interactions (see Fig. 20.2.1). The key is that the DNA clamp is closed by the Hoogsteen interactions (non-Watson-Crick nonpairings), which are weaker than Watson-Crick pairings. However, the DNA clamp opens due to the force when the antibody arrives. The binding of a bivalent macromolecule to the two antigens causes a conformational change that reduces the stability of the triplex complex, with the consequent release of the loaded strand.
DNA clamp
DNA bullet +
Antibody
Released strand
Peptides
Fig. 20.2.1 The DNA nanomachine. A DNA strand (shown in black) labeled with two antigens (green hexagons) can load a nucleic acid strand (blue) through a clamp-like triplex mechanism which uses Hoogsteen-interactions (black hexagons). The binding of a bivalent macromolecule (an antibody) to the two antigens causes a conformational change that reduces the stability of the triplex complex, with the consequent release of the loaded strand.
Nanomachine-Related Topics
235
20.3 VESICLE ORIGAMI: CUBOID PHOSPHOLIPID VESICLES When lipids self-asssemble as vesicles, to minimize the surface tension, the vesicles typically become spherical. There are only a few nonspherical systems, but they require templates to scaffold the structure. However, Neuhaus et al. (2017) reported a 1,2-diaminophospholipid that self-asssembles into a cuboid structure without a scaffold. The bilayer membranes form an exceptionally tight subgel packing, leading to maximization of flat structural elements and minimization of any edges. Wide-angle X-ray scattering measurements suggest that the membrane packs in a herringbone pattern, which is the tightest bilayer packing pattern known. Because of their stiffness, the membranes must be heated above their melting temperature to form vesicles. When the vesicles are subsequently cooled below the melting temperature, they adopt a cuboid shape. Neuhaus et al. (2017) wanted to use the cubes as drug delivery devices. However, the cuboids themselves are too weak for this purpose because of their very long defect lines along the edges. However, such studies have taught us a lot about the physics needed for the next generation of mechanoresponsive drug delivery containers.
20.4 NANOSWIMMERS TO THE BRAIN Recently, artificial microscopic and nanoscopic self-propelling particles (called nano- or microswimmers) have been created. They are used for transporting target chemicals. One of their most difficult tasks is to deliver drugs within the central nervous system (CNS), because they are guarded by the blood–brain barrier (BBB). Joseph et al. (2017) noticed that the largest organ concuming glucose and oxygen is the brain, so that there is their large gradient in the body. If the nanoswimmers can detect the gradient, they can concentrate the swimmers into CNS, if possible passing through BBB. Joseph et al. achieved this by encapsulating glucose oxidase alone or in combination with catalase into nanoscopic and biocompatible asymmetric polymer vesicles (known as polymersomes; see Fig. 20.4.1A and B). They showed that these vesicles self-propel in response to an external gradient of glucose by inducing a slip velocity on their surface, which makes them move in an extremely sensitive way toward higher-concentration regions.
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Glucose oxidase Catalase
20 nm
or
(A)
(B) Fig. 20.4.1 Nanno swimmers to the brain. (A) Schematic figure of asymmetric polymersome, and chemical compositions of fibers on each part. (B) Enzymatic reactions of glucose oxidase and catalase.
They finally demonstrated that the chemotactic behavior of these nanoswimmers resulted in a fourfold increase in penetration to the brain compared to nonchemotactic systems.
20.5 HYDROPHOBIC PHAGE-MIMICKING MEMBRANE ACTIVE ANTIMICROBIALS Jiang et al. (2017) have developed a virus-like polymer that can kill target bacteria, including antibiotic-resistant strains, without harming human cells. In addition, by changing the size and shape of the particle, the target bacteria can be altered.
Nanomachine-Related Topics
237
Jiang et al. (2017) made three polymer nanoparticles: (i) 8 nm wide sphere; (ii) 7 nm wide rod-shaped with 18 nm (short); and (iii) 70 nm (long) length. In the sphere of (i), positively charged, hydrophilic polimer molecular brushes (PMBs) made of poly(4-vinyl-N-methylpyridine iodide) (P4MVP) come out from the cores made of β-cyclodextrin (β-CD). For the rod-shaped nanoparticles of (ii) and (iii), PMBs made of P4MVP grow from the rod-like polymers. Jiang et al. tested nanoparticles to Gram-negative Escheria Coli, Gram-positive Staphylococcus aureus, and multidrug-resistant bacteria such as Pseudomonas aeruginosa. The spherical particles killed 99.9% of both Gram-positive and Gram-negative bacteria and Pseudomonas aeruginosa. The longer particles showed lower antibacterial activity, but were more effective against Gram-negative bacteria than Gram-positive ones. The reason why the nanoparticles are not deadly to human cells is down to the shapes of lipids within cells membranes. The bacterial membranes are rich in phosphoethanolamine lipids with an intrinsic curve, which are easily bent and wrapped by the nanoparticles, resulting in rupture when the nanoparticles gather around. In contrast, human cells are made of flat phosphocholine lipids, forming more rigid membranes.
REFERENCES Barber, D.M., Sch€ onberger, M., Burgstaller, J., Levitz, J., Weaver, C.D., et al., 2016. Optical control of neuronal activity using a light-operated GIRK channel opener (LOGO). Chem. Sci. 7, 2347–2352. Garcı´a-Lo´pez, V., Chen, F., Nilewski, L.G., Duret, G., Aliyan, A., et al., 2017. Molecular machines open cell membranes. Nature 548, 567–572. Jiang, Y., Zheng, W., Kuang, L., Ma, H., Liang, H., 2017. Hydrophilic phage-mimicking membrane active antimicrobials reveal nanostructure-dependent activity and selectivity. ACS Infect. Dis. 3, 676–687. Joseph, A., Contini, C., Cecchin, D., Nyberg, S., Ruiz-Perez, L., et al., 2017. Chemotactic synthetic vesicles: design and applications in blood-brain barrier crossing. Sci. Adv. 3e1700362. Neuhaus, F., Mueller, D., Tanasescu, R., Balog, S., Ishikawa, T., et al., 2017. Vesicle origami: cuboid phospholipid vesicles formed by template-free self-assembly. Angew. Chem. Int. Ed. 56, 6515–6518. Ranallo, S., Prevost-Tremblay, C., Idili, A., Vallee-Belisle, A., Ricci, F., 2017. Antibodypowered nucleic acid release using a DNA-based nanomachine. Nat. Commun. https:// doi.org/10.1038/ncomms15150.
Nanomachine-Related Topics Contents 20.1 Molecular Drill for Opening Cell Membranes 20.2 Antibody-Powered DNA Nanomachines 20.3 Vesicle Origami: Cuboid Phospholipid Vesicles 20.4 Nanoswimmers to the Brain 20.5 Hydrophobic Phage-Mimicking Membrane Active Antimicrobials References
233 234 235 235 236 237
20.1 MOLECULAR DRILL FOR OPENING CELL MEMBRANES Beyond the more common chemical delivery strategies, there are several physical techniques to open the lipid bilayers of cellular membranes. These include electric and magnetic fields, temperature, ultrasonic, or light to put compounds into cells, to release molecular species from cells, or to induce selective cell death (apoptosis). More recently, molecular motors and switches that can change their conformation in a controlled way in response to external stimuli have been used to produce mechanical actions on tissue for biomedical applications (Barber et al., 2016). Garcı´a-Lo´pez et al. (2017) demonstrated that molecular machines can drill through cellular lipid bilayers using the molecular-scale nanomechanical action. After the adsorption of the molecular motors on lipid bilayers and activation of the motors using ultraviolet light, holes are drilled in the cell membranes. Garcı´a-Lo´pez et al. designed molecular motors (see Fig. 20.1.1) and complementary experimental protocols that use nanomechanical action. They also showed that, by changing functional addends (R), the motors can target specific cell surface sites. After the in vitro applications, they expect that molecular machines could also be used in vivo, especially as their design progresses to allow two-photon, nearinfrared, and radio-frequency activation. Biochemistry for Materials Science https://doi.org/10.1016/B978-0-12-817054-0.00020-5
© 2019 Elsevier Inc. All rights reserved.
233
234
Biochemistry for Materials Science
Fig. 20.1.1 Molecular drill for opening cell membranes.
20.2 ANTIBODY-POWERED DNA NANOMACHINES Ranallo et al. (2017) reported an antibody-powered DNA-based nanomachine that can reversibly load and release a molecular cargo on binding to a specific antibody. A DNA strand labeled with two antigens can load a nucleic acid strand through a clamp-like triplex-forming mechanism that uses Hoogsteen-interactions (see Fig. 20.2.1). The key is that the DNA clamp is closed by the Hoogsteen interactions (non-Watson-Crick nonpairings), which are weaker than Watson-Crick pairings. However, the DNA clamp opens due to the force when the antibody arrives. The binding of a bivalent macromolecule to the two antigens causes a conformational change that reduces the stability of the triplex complex, with the consequent release of the loaded strand.
DNA clamp
DNA bullet +
Antibody
Released strand
Peptides
Fig. 20.2.1 The DNA nanomachine. A DNA strand (shown in black) labeled with two antigens (green hexagons) can load a nucleic acid strand (blue) through a clamp-like triplex mechanism which uses Hoogsteen-interactions (black hexagons). The binding of a bivalent macromolecule (an antibody) to the two antigens causes a conformational change that reduces the stability of the triplex complex, with the consequent release of the loaded strand.
Nanomachine-Related Topics
235
20.3 VESICLE ORIGAMI: CUBOID PHOSPHOLIPID VESICLES When lipids self-asssemble as vesicles, to minimize the surface tension, the vesicles typically become spherical. There are only a few nonspherical systems, but they require templates to scaffold the structure. However, Neuhaus et al. (2017) reported a 1,2-diaminophospholipid that self-asssembles into a cuboid structure without a scaffold. The bilayer membranes form an exceptionally tight subgel packing, leading to maximization of flat structural elements and minimization of any edges. Wide-angle X-ray scattering measurements suggest that the membrane packs in a herringbone pattern, which is the tightest bilayer packing pattern known. Because of their stiffness, the membranes must be heated above their melting temperature to form vesicles. When the vesicles are subsequently cooled below the melting temperature, they adopt a cuboid shape. Neuhaus et al. (2017) wanted to use the cubes as drug delivery devices. However, the cuboids themselves are too weak for this purpose because of their very long defect lines along the edges. However, such studies have taught us a lot about the physics needed for the next generation of mechanoresponsive drug delivery containers.
20.4 NANOSWIMMERS TO THE BRAIN Recently, artificial microscopic and nanoscopic self-propelling particles (called nano- or microswimmers) have been created. They are used for transporting target chemicals. One of their most difficult tasks is to deliver drugs within the central nervous system (CNS), because they are guarded by the blood–brain barrier (BBB). Joseph et al. (2017) noticed that the largest organ concuming glucose and oxygen is the brain, so that there is their large gradient in the body. If the nanoswimmers can detect the gradient, they can concentrate the swimmers into CNS, if possible passing through BBB. Joseph et al. achieved this by encapsulating glucose oxidase alone or in combination with catalase into nanoscopic and biocompatible asymmetric polymer vesicles (known as polymersomes; see Fig. 20.4.1A and B). They showed that these vesicles self-propel in response to an external gradient of glucose by inducing a slip velocity on their surface, which makes them move in an extremely sensitive way toward higher-concentration regions.
236
Biochemistry for Materials Science
Glucose oxidase Catalase
20 nm
or
(A)
(B) Fig. 20.4.1 Nanno swimmers to the brain. (A) Schematic figure of asymmetric polymersome, and chemical compositions of fibers on each part. (B) Enzymatic reactions of glucose oxidase and catalase.
They finally demonstrated that the chemotactic behavior of these nanoswimmers resulted in a fourfold increase in penetration to the brain compared to nonchemotactic systems.
20.5 HYDROPHOBIC PHAGE-MIMICKING MEMBRANE ACTIVE ANTIMICROBIALS Jiang et al. (2017) have developed a virus-like polymer that can kill target bacteria, including antibiotic-resistant strains, without harming human cells. In addition, by changing the size and shape of the particle, the target bacteria can be altered.
Nanomachine-Related Topics
237
Jiang et al. (2017) made three polymer nanoparticles: (i) 8 nm wide sphere; (ii) 7 nm wide rod-shaped with 18 nm (short); and (iii) 70 nm (long) length. In the sphere of (i), positively charged, hydrophilic polimer molecular brushes (PMBs) made of poly(4-vinyl-N-methylpyridine iodide) (P4MVP) come out from the cores made of β-cyclodextrin (β-CD). For the rod-shaped nanoparticles of (ii) and (iii), PMBs made of P4MVP grow from the rod-like polymers. Jiang et al. tested nanoparticles to Gram-negative Escheria Coli, Gram-positive Staphylococcus aureus, and multidrug-resistant bacteria such as Pseudomonas aeruginosa. The spherical particles killed 99.9% of both Gram-positive and Gram-negative bacteria and Pseudomonas aeruginosa. The longer particles showed lower antibacterial activity, but were more effective against Gram-negative bacteria than Gram-positive ones. The reason why the nanoparticles are not deadly to human cells is down to the shapes of lipids within cells membranes. The bacterial membranes are rich in phosphoethanolamine lipids with an intrinsic curve, which are easily bent and wrapped by the nanoparticles, resulting in rupture when the nanoparticles gather around. In contrast, human cells are made of flat phosphocholine lipids, forming more rigid membranes.
REFERENCES Barber, D.M., Sch€ onberger, M., Burgstaller, J., Levitz, J., Weaver, C.D., et al., 2016. Optical control of neuronal activity using a light-operated GIRK channel opener (LOGO). Chem. Sci. 7, 2347–2352. Garcı´a-Lo´pez, V., Chen, F., Nilewski, L.G., Duret, G., Aliyan, A., et al., 2017. Molecular machines open cell membranes. Nature 548, 567–572. Jiang, Y., Zheng, W., Kuang, L., Ma, H., Liang, H., 2017. Hydrophilic phage-mimicking membrane active antimicrobials reveal nanostructure-dependent activity and selectivity. ACS Infect. Dis. 3, 676–687. Joseph, A., Contini, C., Cecchin, D., Nyberg, S., Ruiz-Perez, L., et al., 2017. Chemotactic synthetic vesicles: design and applications in blood-brain barrier crossing. Sci. Adv. 3e1700362. Neuhaus, F., Mueller, D., Tanasescu, R., Balog, S., Ishikawa, T., et al., 2017. Vesicle origami: cuboid phospholipid vesicles formed by template-free self-assembly. Angew. Chem. Int. Ed. 56, 6515–6518. Ranallo, S., Prevost-Tremblay, C., Idili, A., Vallee-Belisle, A., Ricci, F., 2017. Antibodypowered nucleic acid release using a DNA-based nanomachine. Nat. Commun. https:// doi.org/10.1038/ncomms15150.