Monodisperse ultra-large-pore silica coated polystyrene core-shell microbeads via layer-by-layer assembly for nano-micro composite

Abstract

Polystyrene(PS)@SiO₂ core-shell microbeads with large pore and large particle size were prepared via layer-by-layer(LBL)assembly technique for potential applications in nano-micro composites. Negative silica nanoparticles synthesized via modified Stöber method and cationic poly(diallyldimethylammonium chloride)were alternately adsorbed on the surface of microbeads. Zeta potential, size, and morphology of the microbeads were monitored during LBL assembly process to ensure the successful deposition of silica nanoparticles. The porous shell was characterized using nitrogen adsorption and desorption analyses, and the surface area, volume and diameter of the pores were derived. It is found that the porous shell thickness and the pore size can be tuned by changing the coating times of silica nanoparticles. Finally, PS@SiO₂ core-shell microbeads with 5,μm PS solid core and 350,nm mesoporous shell(mean BJH pore diameter is ~27,nm)were used to load CdSe/ZnS quantum dots(QDs). The fluorescence microscopic image and the optical amplification of the QDs-embedded microbeads (QDBs)indicate that the as-prepared core-shell microbeads can provide adequate space for QDs and may be useful for further application of nano-micro composites.

Keywords

large pore mesoporous silica / core-shell structure / microbeads / layer-by-layer assembly / nano-micro composite / amplified spontaneous emission

References

[1] Borgia I, Brunetti B, Mariani I, et al. Heterogeneous distribution of metal nanocrystals in glazes of historical pottery[J]. Applied Surface Science, 2002, 185(3): 206-216.

[2] Zhang W X, Wang C B, Lien H L. Treatment of chlorinated organic contaminants with nanoscale bimetallic particles[J]. Catalysis Today, 1998, 40(4): 387-395.

[3] Ferris M M, McCabe M O, Doan L G, et al. Rapid enumeration of respiratory viruses[J]. Analytical Chemistry, 2002, 74(8): 1849-1856.

[4] Elliott D W, Zhang Weixian. Field assessment of nanoscale bimetallic particles for groundwater treatment [J]. Environmental Science & Technology, 2001, 35(24): 4922-4926.

[5] Kong J, Franklin N R, Zhou C, et al. Nanotube molecular wires as chemical sensors[J]. Science, 2000, 287(5453): 622-625.

[6] Wei S, Wang Q, Zhu J, et al. Multifunctional composite core-shell nanoparticles[J]. Nanoscale, 2011, 3(11): 4474-4502.

[7] Gao X H, Han M Y, Nie S M. Optically encoded microspheres for high-throughput analysis of genes and proteins[C]. International Symposium on Biomedical Optics. International Society for Optics and Photonics, 2002, 210-217.

[8] Nie S M. Semiconductor quantum dots and encoded beads for probing intracellular transport and signaling[J]. Abstracts of Papers of the American Chemical Society, 2005, 229: 006.

[9] Xiang Y, Zhang Y Y, Chang Y, et al. Reverse-micelle synthesis of electrochemically encoded quantum dot barcodes: Application to electronic coding of a cancer marker[J]. Analytical Chemistry, 2010, 82(3): 1138-1141.

[10] Liu G, He Y. Facile synthesis of nanocrystal encoded fluorescent silica microspheres[J]. Journal of Colloid and Interface Science, 2012, 388: 86-91.

[11] Malko A V, Mikhailovsky A A, Petruska M A, et al. From amplified spontaneous emission to microring lasing using nanocrystal quantum dot solids[J]. Applied Physics Letters, 2002, 81(7): 1303-1305.

[12] Snee P T, Chan Y, Nocera D G, et al. Whisperinggallery-mode lasing from a semiconductor nanocrystal/microsphere resonator composite [J]. Advanced Materials, 2005, 17(9): 1131-1136.

[13] Li M, You G, Wang A Y, et al. Lasing and magnetic microbeads loaded with colloidal quantum dots and iron oxide nanocrystals[J]. Nanoscale, 2013, 5(20): 9598-9603.

[14] Klimov V I, Mikhailovsky A A, Xu S, et al. Optical gain and stimulated emission in nanocrystal quantum dots[J]. Science, 2000, 290(5490): 314-317.

[15] Du X, He Junhui. Spherical silica micro/nanomaterials with hierarchical structures: Synthesis and applications[J]. Nanoscale, 2011, 3(10): 3984-4002.

[16] Lim J-S, Lee K, Choi J-N, et al. Intracellular protein delivery by hollow mesoporous silica capsules with a large surface hole[J]. Nanotechnology, 2012, 23(8): 085-101.

[17] Fuertes A B, Valle-Vigón P, Sevilla M. Synthesis of colloidal silica nanoparticles of a tunable mesopore size and their application to the adsorption of biomolecules[J]. Journal of Colloid and Interface Science, 2010, 349(1): 173-180.

[18] Zhang J, Li X, Rosenholm J M, et al. Synthesis and characterization of pore size-tunable magnetic mesoporous silica nanoparticles[J]. Journal of Colloid and Interface Science, 2011, 361(1): 16-24.

[19] Shin H-S, Hwang Y-K, Huh Seong. Facile preparation of ultra-large pore mesoporous silica nanoparticles and their application to the encapsulation of large guest molecules[J]. ACS Applied Materials & Interfaces, 2014, 6(3): 1740-1746.

[20] Chen Y, Chu C, Zhou Y, et al. Reversible porestructure evolution in hollow silica nanocapsules: Large pores for sirna delivery and nanoparticle collecting[J]. Small, 2011, 7(20): 2935-2944.

[21] Wu S-H, Mou C-Y, Lin H-Ping. Synthesis of mesoporous silica nanoparticles[J]. Chemical Society Reviews, 2013, 42(9): 3862-3875.

[22] Anderson D J. Process for Forming Large Silica Spheres by Low Temperature Nucleation: US 5425930[P], 1995.

[23] Qi G, Wang Y, Estevez L, et al. Facile and scalable synthesis of monodispersed spherical capsules with a mesoporous shell[J]. Chemistry of Materials, 2010, 22(9): 2693-2695.

[24] Graf C, Vossen D L J, Imhof A, et al. A general method to coat colloidal particles with silica[J]. Langmuir, 2003, 19(17): 6693-6700.

[25] Whitaker K A, Furst E M. Layer-by-layer synthesis of mechanically robust solvent-permeable silica nanoshells [J]. Langmuir, 2013, 30(2): 584-591.

[26] Che H X, Yeap S P, Ahmad A L, et al. Layer-by-layer assembly of iron oxide magnetic nanoparticles decorated silica colloid for water remediation [J]. Chemical Engineering Journal, 2014, 243: 68-78.

[27] Tang Y, Zhao Y, Wang X, et al. Layer-bylayer assembly of silica nanoparticles on 3d fibrous scaffolds: Enhancement of osteoblast cell adhesion, proliferation, and differentiation[J]. Journal of Biomedical Materials Research Part A, 2014, 102(11): 3803-3812.

[28] Stöber W, Fink A, Bohn E. Controlled growth of monodisperse silica spheres in the micron size range [J]. Journal of Colloid and Interface Science, 1968, 26(1): 62-69.

[29] Li J J, Wang Y A, Guo W, et al. Largescale synthesis of nearly monodisperse CdSe/CdS core/shell nanocrystals using air-stable reagents via successive ion layer adsorption and reaction[J]. Journal of the American Chemical Society, 2003, 125(41): 12567-12575.

[30] Sing K SW. Reporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity(recommendations 1984)[J]. Pure and Applied Chemistry, 1985, 57(4): 603-619.

[31] Liao Y, Xing G, Mishra N, et al. Low threshold, amplified spontaneous emission from core seeded semiconductor nanotetrapods incorporated into a sol-gel matrix[J]. Advanced Materials, 2012, 24(23): OP159-OP164.