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A surfactant template-assisted strategy for synthesis of ZIF-8 hollow nanospheres
Author’s Accepted Manuscript A surfactant template-assisted strategy for synthesis of ZIF-8 hollow nanospheres Xin Cao, Lin Dai, Luying Wang, Jing Liu, Jiandu Lei www.elsevier.com
PII: DOI: Reference:
S0167-577X(15)30575-9 http://dx.doi.org/10.1016/j.matlet.2015.09.061 MLBLUE19577
To appear in: Materials Letters Received date: 14 July 2015 Revised date: 31 August 2015 Accepted date: 12 September 2015 Cite this article as: Xin Cao, Lin Dai, Luying Wang, Jing Liu and Jiandu Lei, A surfactant template-assisted strategy for synthesis of ZIF-8 hollow nanospheres, Materials Letters, http://dx.doi.org/10.1016/j.matlet.2015.09.061 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.
A surfactant template-assisted strategy for synthesis of ZIF-8 hollow nanospheres Xin Cao,a,b Lin Dai,a Luying Wang,a Jing Liu,a Jiandu Lei*a,b a
MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy,
Beijing Forestry University, Beijing 100083, China b
Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University,
Beijing 100083, China *Corresponding author. E-mail address: [email protected] Abstract Metal-organic frameworks (MOFs) hollow nanospheres have been widely studied for encapsulation of catalysts and target drugs. The materials ZIF-8 is a typical example of zeolitic imidazolate frameworks. In this reported work, ZIF-8 hollow nanospheres were synthesized by using surfactant. An anti-cancer drug 10-Hydroxy Camptothecin (HCPT) was successfully encapsulated into these novel ZIF-8 hollow nanospheres. Transmission electron microscopy and scanning electron microscopy revealed that the ZIF-8 nanospheres and HCPT@ZIF-8 hollow nanospheres were in uniform diameters of 250 nm and 950 nm, respectively. Furthermore, confocal laser scanning microscope also was used to examine the fluorescence response of the HCPT encapsulated in HCPT@ZIF-8 hollow nanospheres. It was found that the HCPT was successfully encapsulated. This fabrication method provides a feasible way for the synthesis of useful MOFs hollow nanospheres. Keywords: biomaterials; microstructure; nanoparticles
1
1. Introduction Metal-organic frameworks (MOFs) composed of metal ions with organic linkers have been developed as new materials in recent years [1]. They attracted by great attentions because of their nanostructure and unique properties. MOFs are promising candidates for gas storage and separation due to their low density and high surface area [2,3]. They have also been investigated for micro-solid phase extraction and drug delivery because of their diverse pore size [4,5]. In addition, MOFs have played a vital role in chromatographic analysis and sensor detection [6,7]. Despite their rapid development, many problems still remain and limit their use such as low selectivity and production difficulties. These problems also include the synthesis of MOFs hollow nanospheres. Up to now, MOFs hollow nanospheres were fabricated primarily by using the etching method. In this manner, MOF nanospheres are produced by etching the precursor materials that were synthesized as the cores. Lee and co-workers successfully synthesized ZIF-8 hollow microspheres using this method [8]. Interfacial synthesis and spray-drying are two other emerging methods for preparing MOF nanospheres [9,10]. The former has been achieved by mixing two kinds of immiscible solutions which cause the precursors in the different solutions to react at the solution interface to form hollow structure. The later approach was realized by spraying atomized droplets that contained the precursors in the air. When the two types of droplets were mixed, the precursors slowly reacted resulting in the production of the hollow structure. Recently, MOFs
2
hollow nanospheres were synthesized using an emulsion procedure. Wang and co-workers synthesized MOF-5 and Fe-MOF-5 hollow nanospheres using an emulsion process [11]. Pang and co-workers also fabricated mono-dispersed Fe-soc-MOF hollow particles using an emulsion [12]. Despite to these advancements, more methods for the synthesis of MOFs hollow nanospheres are still needed to match emerging applications. In this study, we report on a surfactant-templated strategy for the preparation of MOFs hollow nanospheres. In this work, ZIF-8 hollow nanospheres and HCPT@ZIF-8 hollow nanospheres were successfully synthesized. This method provides a novel and feasible method for synthesis of various types of MOFs hollow nanospheres. 2. Experimental Details The reagents used in this work included sodium dodecyl sulfate (SDS) (99%, Sigma-Aldrich), Zn(NO3)2·6H2O (98%, Sigma-Aldrich), 2-methyl-imidazole (99%, Sigma-Aldrich), 10-Hydroxy Camptothecin (HCPT) (99%, Sigma-Aldrich), Dimethyl sulfoxide (DMSO) (99%, Sigma-Aldrich), deionized (DI) water and others were obtained from Beijing Chemical Works Co., Ltd, China. Preparation of ZIF-8 hollow nanospheres: Firstly, SDS (0.54 g) was dissolved in DI water (40 mL) for 3 h at room temperature. After that, Zn(NO3)2•6H2O (1.53 g) was dissolved into the SDS solution for 10 min. Then 2-methyl-imidazole (3.38 g) was added into the mixture above and reacted for 30 min. The products were washed by DI water and separated via centrifugation at 2000 r/min for 10 min for several times. Then the products were dried in the air under 100 ºC for 24 h.
3
Preparation of HCPT@ZIF-8 hollow nanospheres: HCPT (0.0027 g) and SDS (0.054 g) were dissolved in DMSO (0.2 mL) under ultrasonic for 10 min at room temperature. Then the DMSO solution with HCPT and SDS was dispersed droplets in water (7.8 mL) stirring for 2 min and left to stand for 2 h. Zn(NO3)2•6H2O (0.68 g) was dissolved to the above mixture solution for 10 min. Then 2-methyl-imidazole (1.563 g) was added into the above mixture and react for 30 min. The products were washed by DI water and separated via centrifugation at 4000 r/min for 5 min for several times. Then the products were dried in the air under 100 ºC for 24 h. 3. Results and Discussion Composed of Zn2+ and 2-methyl-imidazole, ZIF-8 is a typical example of zeolitic imidazolate frameworks (ZIFs). In the ZIF-8 crystal, each zinc ion is connected to the 2-methyl-imidazolate by four coordination bonds. Each 2-methyl-imidazolate molecule is combined with a pair of zinc ions. The four-connected zinc ion centers and two-connected 2-methyl-imidazolate form a tight framework with hexagonal topology. The reaction that produces this process is shown as below [13,14].
Ζn(ΝΟ3 ) 2 (2 x y)Hmin nano - [Zn(min)2x (Hmim) y ]x (2 x)H 2NO3
In this reported study, the preparation process for the ZIF-8 hollow nanosphere is demonstrated in Fig. 1. As shown, initially SDS was dissolved in DI water. When the concentration of SDS was above the critical micelle concentration, it was assembled into micelles with the hydrophilic group outside and hydrophobic inside. When Zn(NO3)2•6H2O was added into the solution, Zn2+ attached to the hydrophilic groups
4
due to the p-p interaction between the Zn2+ and oxygen atoms. When 2-methyl-imidazole was added to this mixed solution, it quickly reacted with Zn2+ and generated the ZIF-8 crystal forming a hollow structure on the surface of micelles.
Fig. 1. Preparation of ZIF-8 hollow nanospheres. The structure of ZIF-8 hollow nanospheres was characterized using transmission electron microscopy (TEM) JEM-1010. The resulting patterns showed that the average size of the ZIF-8 hollow nanospheres was 250 nm (Fig. 2a and b). Scanning electron microscopy (SEM) of SU-8020 was also conducted to characterize the morphology of the ZIF-8 hollow nanospheres (Fig. 2c). The results revealed that the ZIF-8 hollow nanospheres were potentially productive by virtue of their large cavities. In addition, X-ray diffraction (XRD) patterns of the product were obtained using a SHIMADZU XRD-6000 to characterize ZIF-8 hollow nanospheres. The XRD pattern of the ZIF-8 hollow nanospheres matched well with the ZIF-8 crystal patterns (Fig. 2d). These results validated the successful synthesis of hollow nanospheres by ZIF-8 crystal. Fourier transformed infrared resonance (FT-IR) spectra from 4000 to 600 cm-1 of the product were obtained using a Nicolet iN10 spectrophotometer which helped to characterize ZIF-8 hollow nanospheres (Fig. 2e). In this figure, the adsorption bands at of 500-1500 cm-1 can be attributed to the plane bending and stretching of imidazole ring. 5
The adsorption band at 1584 cm-1 can be attributed to the stretching mode of C=N in the imidazole. Both the 2929 cm-1 and 3135 cm-1 adsorption reflected C-H stretching.
Fig. 2. (a,b) TEM of ZIF-8 hollow nanospheres (scale bar 500 nm; scale bar 100 nm). (c) SEM of ZIF-8 hollow nanospheres (scale bar 1 μm). (d) XRD of ZIF-8 hollow nanospheres and ZIF-8. (e) FT-IR of ZIF-8 hollow nanospheres and ZIF-8. In this work, an anti-cancer drug HCPT was successfully encapsulated into ZIF-8 hollow nanospheres. As evidence of this, confocal laser scanning microscope (CLSM) using a Leica SP5 was used to detect the fluorescence response of HCPT encapsulated in ZIF-8 hollow nanospheres. The process for preparing the HCPT@ZIF-8 hollow nanospheres is shown in Fig. 3a. As shown, initially, HCPT and SDS were dissolved in DMSO and the DMSO solution was added droppwise to DI water with stirring. As a result, the SDS assembly constructed into micelles with HCPT inside. When Zn(NO3)2•6H2O and 2-methyl-imidazole was added in sequence, HCPT@ZIF-8 hollow 6
nanospheres were obtained (containing more than 10 wt% of transported drug versus the carrier material). In Fig. 3b green fluorescence of HCPT was observed. The fluorescence patterns revealed that HCPT was successfully encapsulated in the ZIF-8 hollow nanospheres and HCPT@ZIF-8 hollow nanospheres were in a uniform of 950 nm with high productive (Fig. 3d and e).
Fig. 3. (a) Preparation process for HCPT@ZIF-8 hollow nanospheres. (b,c) CLSM of HCPT@ZIF-8 hollow nanospheres (scale bar 1 μm). (d,e) SEM of HCPT@ZIF-8 hollow nanospheres (scale bar 1 μm; scale bar 100 nm). 4. Conclusions In summary, we reported here on simple method for the synthesis of ZIF-8 hollow nanospheres. The ZIF-8 hollow nanospheres process was highly productive yielding in a uniform size. In addition, an anti-cancer drug HCPT was encapsulated into ZIF-8 hollow nanospheres. This method provides a feasible process for fabricating different MOFs hollow nanospheres. These uniquely structured MOFs hollow nanospheres will 7
be useful for novel practical applications such as drug delivery, catalysis and sensor technology. Acknowledgements This work was supported by the China State Forestry Administration 948 Project (No.2014-4-35), and National Science Foundation of Beijing, Chian (Grant No.2142024), and the National Natural Science Foundation of China (No.21406013, 21576029). References [1] Furukawa H, Cordova KE, O’Keeffe M, Yaghi OM. Science 2013;341: 974-986. [2] Rowsell JLC, Spencer EC, Eckert J, Howard JAK, Yaghi OM. Science 2005;309 :1350–4. [3] Rosi NL, Eckert J, Eddaoudi M, Vodak DT, Kim J, O’Keeffe M, et al. Science 2003;300 :1127–9. [4] Wang Y, Jin S, Wang Q, Lu G, Jiang J, Zhu D. J Chromatogr A 2013;1291:27–32. [5] Motakef-Kazemi N, Shojaosadati SA, Morsali A. Microporous Mesoporous Mater 2014;186:73–9. [6] Centrone A, Santiso EE, Hatton TA. Small 2011;7:2356–64. [7] Ameloot R, Liekens A, Alaerts L, Maes M, Galarneau A, Coq B, et al. Eur J Inorg Chem 2010;2010:3735–8. [8] Lee HJ, Cho W, Oh M. Chem Commun 2012;48:221–3. [9] Ameloot R, Vermoortele F, Vanhove W, Roeffaers MBJ, Sels BF, De Vos DE. Nat Chem 2011;3:382–7. [10] Carné-Sánchez A, Imaz I, Cano-Sarabia M, Maspoch D. Nat Chem 2013;5:203–11. [11] Zhang Z, Chen Y, Xu X, Zhang J, Xiang G, He W, et al. Angew Chemie 2014;126:439–43. [12] Pang M, Cairns AJ, Liu Y, Belmabkhout Y, Zeng HC, Eddaoudi M. J Am Chem Soc 2013;135:10234–7. [13] Pan Y, Liu Y, Zeng G, Zhao L, Lai Z. Chem Commun 2011;47:2071–3. [14] Cravillon J, Münzer S, Lohmeier S-J, Feldhoff A, Huber K, Wiebcke M. Chem Mater 2009;21:1410–2.
8
Highlights
ZIF-8 hollow nanospheres were successfully synthesized.
10-Hydroxy Camptothecin was encapsulated into ZIF-8 hollow nanospheres.
This method provides a feasible way to construct MOFs hollow nanospheres.
9
PII: DOI: Reference:
S0167-577X(15)30575-9 http://dx.doi.org/10.1016/j.matlet.2015.09.061 MLBLUE19577
To appear in: Materials Letters Received date: 14 July 2015 Revised date: 31 August 2015 Accepted date: 12 September 2015 Cite this article as: Xin Cao, Lin Dai, Luying Wang, Jing Liu and Jiandu Lei, A surfactant template-assisted strategy for synthesis of ZIF-8 hollow nanospheres, Materials Letters, http://dx.doi.org/10.1016/j.matlet.2015.09.061 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.
A surfactant template-assisted strategy for synthesis of ZIF-8 hollow nanospheres Xin Cao,a,b Lin Dai,a Luying Wang,a Jing Liu,a Jiandu Lei*a,b a
MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy,
Beijing Forestry University, Beijing 100083, China b
Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University,
Beijing 100083, China *Corresponding author. E-mail address: [email protected] Abstract Metal-organic frameworks (MOFs) hollow nanospheres have been widely studied for encapsulation of catalysts and target drugs. The materials ZIF-8 is a typical example of zeolitic imidazolate frameworks. In this reported work, ZIF-8 hollow nanospheres were synthesized by using surfactant. An anti-cancer drug 10-Hydroxy Camptothecin (HCPT) was successfully encapsulated into these novel ZIF-8 hollow nanospheres. Transmission electron microscopy and scanning electron microscopy revealed that the ZIF-8 nanospheres and HCPT@ZIF-8 hollow nanospheres were in uniform diameters of 250 nm and 950 nm, respectively. Furthermore, confocal laser scanning microscope also was used to examine the fluorescence response of the HCPT encapsulated in HCPT@ZIF-8 hollow nanospheres. It was found that the HCPT was successfully encapsulated. This fabrication method provides a feasible way for the synthesis of useful MOFs hollow nanospheres. Keywords: biomaterials; microstructure; nanoparticles
1
1. Introduction Metal-organic frameworks (MOFs) composed of metal ions with organic linkers have been developed as new materials in recent years [1]. They attracted by great attentions because of their nanostructure and unique properties. MOFs are promising candidates for gas storage and separation due to their low density and high surface area [2,3]. They have also been investigated for micro-solid phase extraction and drug delivery because of their diverse pore size [4,5]. In addition, MOFs have played a vital role in chromatographic analysis and sensor detection [6,7]. Despite their rapid development, many problems still remain and limit their use such as low selectivity and production difficulties. These problems also include the synthesis of MOFs hollow nanospheres. Up to now, MOFs hollow nanospheres were fabricated primarily by using the etching method. In this manner, MOF nanospheres are produced by etching the precursor materials that were synthesized as the cores. Lee and co-workers successfully synthesized ZIF-8 hollow microspheres using this method [8]. Interfacial synthesis and spray-drying are two other emerging methods for preparing MOF nanospheres [9,10]. The former has been achieved by mixing two kinds of immiscible solutions which cause the precursors in the different solutions to react at the solution interface to form hollow structure. The later approach was realized by spraying atomized droplets that contained the precursors in the air. When the two types of droplets were mixed, the precursors slowly reacted resulting in the production of the hollow structure. Recently, MOFs
2
hollow nanospheres were synthesized using an emulsion procedure. Wang and co-workers synthesized MOF-5 and Fe-MOF-5 hollow nanospheres using an emulsion process [11]. Pang and co-workers also fabricated mono-dispersed Fe-soc-MOF hollow particles using an emulsion [12]. Despite to these advancements, more methods for the synthesis of MOFs hollow nanospheres are still needed to match emerging applications. In this study, we report on a surfactant-templated strategy for the preparation of MOFs hollow nanospheres. In this work, ZIF-8 hollow nanospheres and HCPT@ZIF-8 hollow nanospheres were successfully synthesized. This method provides a novel and feasible method for synthesis of various types of MOFs hollow nanospheres. 2. Experimental Details The reagents used in this work included sodium dodecyl sulfate (SDS) (99%, Sigma-Aldrich), Zn(NO3)2·6H2O (98%, Sigma-Aldrich), 2-methyl-imidazole (99%, Sigma-Aldrich), 10-Hydroxy Camptothecin (HCPT) (99%, Sigma-Aldrich), Dimethyl sulfoxide (DMSO) (99%, Sigma-Aldrich), deionized (DI) water and others were obtained from Beijing Chemical Works Co., Ltd, China. Preparation of ZIF-8 hollow nanospheres: Firstly, SDS (0.54 g) was dissolved in DI water (40 mL) for 3 h at room temperature. After that, Zn(NO3)2•6H2O (1.53 g) was dissolved into the SDS solution for 10 min. Then 2-methyl-imidazole (3.38 g) was added into the mixture above and reacted for 30 min. The products were washed by DI water and separated via centrifugation at 2000 r/min for 10 min for several times. Then the products were dried in the air under 100 ºC for 24 h.
3
Preparation of HCPT@ZIF-8 hollow nanospheres: HCPT (0.0027 g) and SDS (0.054 g) were dissolved in DMSO (0.2 mL) under ultrasonic for 10 min at room temperature. Then the DMSO solution with HCPT and SDS was dispersed droplets in water (7.8 mL) stirring for 2 min and left to stand for 2 h. Zn(NO3)2•6H2O (0.68 g) was dissolved to the above mixture solution for 10 min. Then 2-methyl-imidazole (1.563 g) was added into the above mixture and react for 30 min. The products were washed by DI water and separated via centrifugation at 4000 r/min for 5 min for several times. Then the products were dried in the air under 100 ºC for 24 h. 3. Results and Discussion Composed of Zn2+ and 2-methyl-imidazole, ZIF-8 is a typical example of zeolitic imidazolate frameworks (ZIFs). In the ZIF-8 crystal, each zinc ion is connected to the 2-methyl-imidazolate by four coordination bonds. Each 2-methyl-imidazolate molecule is combined with a pair of zinc ions. The four-connected zinc ion centers and two-connected 2-methyl-imidazolate form a tight framework with hexagonal topology. The reaction that produces this process is shown as below [13,14].
Ζn(ΝΟ3 ) 2 (2 x y)Hmin nano - [Zn(min)2x (Hmim) y ]x (2 x)H 2NO3
In this reported study, the preparation process for the ZIF-8 hollow nanosphere is demonstrated in Fig. 1. As shown, initially SDS was dissolved in DI water. When the concentration of SDS was above the critical micelle concentration, it was assembled into micelles with the hydrophilic group outside and hydrophobic inside. When Zn(NO3)2•6H2O was added into the solution, Zn2+ attached to the hydrophilic groups
4
due to the p-p interaction between the Zn2+ and oxygen atoms. When 2-methyl-imidazole was added to this mixed solution, it quickly reacted with Zn2+ and generated the ZIF-8 crystal forming a hollow structure on the surface of micelles.
Fig. 1. Preparation of ZIF-8 hollow nanospheres. The structure of ZIF-8 hollow nanospheres was characterized using transmission electron microscopy (TEM) JEM-1010. The resulting patterns showed that the average size of the ZIF-8 hollow nanospheres was 250 nm (Fig. 2a and b). Scanning electron microscopy (SEM) of SU-8020 was also conducted to characterize the morphology of the ZIF-8 hollow nanospheres (Fig. 2c). The results revealed that the ZIF-8 hollow nanospheres were potentially productive by virtue of their large cavities. In addition, X-ray diffraction (XRD) patterns of the product were obtained using a SHIMADZU XRD-6000 to characterize ZIF-8 hollow nanospheres. The XRD pattern of the ZIF-8 hollow nanospheres matched well with the ZIF-8 crystal patterns (Fig. 2d). These results validated the successful synthesis of hollow nanospheres by ZIF-8 crystal. Fourier transformed infrared resonance (FT-IR) spectra from 4000 to 600 cm-1 of the product were obtained using a Nicolet iN10 spectrophotometer which helped to characterize ZIF-8 hollow nanospheres (Fig. 2e). In this figure, the adsorption bands at of 500-1500 cm-1 can be attributed to the plane bending and stretching of imidazole ring. 5
The adsorption band at 1584 cm-1 can be attributed to the stretching mode of C=N in the imidazole. Both the 2929 cm-1 and 3135 cm-1 adsorption reflected C-H stretching.
Fig. 2. (a,b) TEM of ZIF-8 hollow nanospheres (scale bar 500 nm; scale bar 100 nm). (c) SEM of ZIF-8 hollow nanospheres (scale bar 1 μm). (d) XRD of ZIF-8 hollow nanospheres and ZIF-8. (e) FT-IR of ZIF-8 hollow nanospheres and ZIF-8. In this work, an anti-cancer drug HCPT was successfully encapsulated into ZIF-8 hollow nanospheres. As evidence of this, confocal laser scanning microscope (CLSM) using a Leica SP5 was used to detect the fluorescence response of HCPT encapsulated in ZIF-8 hollow nanospheres. The process for preparing the HCPT@ZIF-8 hollow nanospheres is shown in Fig. 3a. As shown, initially, HCPT and SDS were dissolved in DMSO and the DMSO solution was added droppwise to DI water with stirring. As a result, the SDS assembly constructed into micelles with HCPT inside. When Zn(NO3)2•6H2O and 2-methyl-imidazole was added in sequence, HCPT@ZIF-8 hollow 6
nanospheres were obtained (containing more than 10 wt% of transported drug versus the carrier material). In Fig. 3b green fluorescence of HCPT was observed. The fluorescence patterns revealed that HCPT was successfully encapsulated in the ZIF-8 hollow nanospheres and HCPT@ZIF-8 hollow nanospheres were in a uniform of 950 nm with high productive (Fig. 3d and e).
Fig. 3. (a) Preparation process for HCPT@ZIF-8 hollow nanospheres. (b,c) CLSM of HCPT@ZIF-8 hollow nanospheres (scale bar 1 μm). (d,e) SEM of HCPT@ZIF-8 hollow nanospheres (scale bar 1 μm; scale bar 100 nm). 4. Conclusions In summary, we reported here on simple method for the synthesis of ZIF-8 hollow nanospheres. The ZIF-8 hollow nanospheres process was highly productive yielding in a uniform size. In addition, an anti-cancer drug HCPT was encapsulated into ZIF-8 hollow nanospheres. This method provides a feasible process for fabricating different MOFs hollow nanospheres. These uniquely structured MOFs hollow nanospheres will 7
be useful for novel practical applications such as drug delivery, catalysis and sensor technology. Acknowledgements This work was supported by the China State Forestry Administration 948 Project (No.2014-4-35), and National Science Foundation of Beijing, Chian (Grant No.2142024), and the National Natural Science Foundation of China (No.21406013, 21576029). References [1] Furukawa H, Cordova KE, O’Keeffe M, Yaghi OM. Science 2013;341: 974-986. [2] Rowsell JLC, Spencer EC, Eckert J, Howard JAK, Yaghi OM. Science 2005;309 :1350–4. [3] Rosi NL, Eckert J, Eddaoudi M, Vodak DT, Kim J, O’Keeffe M, et al. Science 2003;300 :1127–9. [4] Wang Y, Jin S, Wang Q, Lu G, Jiang J, Zhu D. J Chromatogr A 2013;1291:27–32. [5] Motakef-Kazemi N, Shojaosadati SA, Morsali A. Microporous Mesoporous Mater 2014;186:73–9. [6] Centrone A, Santiso EE, Hatton TA. Small 2011;7:2356–64. [7] Ameloot R, Liekens A, Alaerts L, Maes M, Galarneau A, Coq B, et al. Eur J Inorg Chem 2010;2010:3735–8. [8] Lee HJ, Cho W, Oh M. Chem Commun 2012;48:221–3. [9] Ameloot R, Vermoortele F, Vanhove W, Roeffaers MBJ, Sels BF, De Vos DE. Nat Chem 2011;3:382–7. [10] Carné-Sánchez A, Imaz I, Cano-Sarabia M, Maspoch D. Nat Chem 2013;5:203–11. [11] Zhang Z, Chen Y, Xu X, Zhang J, Xiang G, He W, et al. Angew Chemie 2014;126:439–43. [12] Pang M, Cairns AJ, Liu Y, Belmabkhout Y, Zeng HC, Eddaoudi M. J Am Chem Soc 2013;135:10234–7. [13] Pan Y, Liu Y, Zeng G, Zhao L, Lai Z. Chem Commun 2011;47:2071–3. [14] Cravillon J, Münzer S, Lohmeier S-J, Feldhoff A, Huber K, Wiebcke M. Chem Mater 2009;21:1410–2.
8
Highlights
ZIF-8 hollow nanospheres were successfully synthesized.
10-Hydroxy Camptothecin was encapsulated into ZIF-8 hollow nanospheres.
This method provides a feasible way to construct MOFs hollow nanospheres.
9