Wenjing Lin

Controlled construction of gold nanoparticles in situ from β-cyclodextrin based unimolecular micelles for in vitro computed tomography imaging

The development of nanomaterials as highly efficient contrast agents for tumor computed tomography (CT) imaging still remains a huge challenge. In this study, a novel and facile approach to fabricate unimolecular micelles-stablized gold nanoparticles (AuNPs) without external reductant for in vitro targeted CT imaging was described. Amphiphilic 21-arm star-like polymers β-cyclodextrin-g-{poly(2-(dimethylamino)ethyl methacrylate)-poly(2-hydroxyethyl methacrylate)-poly[poly(ethylene glycol) methyl ether methacrylate]} [β-CD-g-(PDMA-b-PHEMA-b-PPEGMA)] was firstly synthesized and proved to form unimolecular core-middle layer-shell-type micelles in water through experimental and computer simulation results. Taking advantage of the reducing groups of PDMA block, AuNPs were decorated in the micellar PDMA block because of the in situ reduction of gold ions, which were absorbed by the PDMA chains in the core layer with a narrow nanoparticle size distribution. This strategy could prevent aggregation of AuNPs, which were capable of being employing as a highly effective probe for specific CT imaging in vitro. Importantly, the β-CD-g-(PDMA-b-PHEMA-b-PPEGMA)/AuNPs incubated with HepG2 cells, displayed more intense X-ray attenuation property (>37%) than conventional iodine-based CT imaging agent (Omnipaque) and also possessed a satisfying cytocompatibility in the given concentration range. The facile fabrication procedures and the efficiency of CT imaging render the novel hybrid unimolecular micelles to become potent candidates for applications in tumor-targeted CT imaging.

Fabrication of Ordered Nanopattern by using ABC Triblock Copolymer with Salt in Toluene

Ordered nanopatterns of triblock copolymer polystyrene-block-poly(2-vinylpyridine)-block- poly (ethylene oxide)(PS-b-P2VP-b-PEO) have been achieved by the addition of lithium chloride (LiCl). The morphological and structural evolution of PS-b-P2VP-b-PEO/LiCl thin films were systematically investigated by varying different experimental parameters, including the treatment for polymer solution after the addition of LiCl, the time scale of ultrasonic treatment and the molar ratio of Li+ ions to the total number of oxygen atoms (O) in PEO block and the nitrogen atoms (N) in P2VP block. When toluene was used as the solvent for LiCl, ordered nanopattern with cylinders or nanostripes could be obtained after spin-coating. The mechanism of nanopattern transformation was related to the loading of LiCl in different microdomains.

Tunable Electromagnetic Enhancement of Gold Nanoparticle Arrays

In this paper, triblock copolymer polyisoprene-block-polystyrene-block-poly(2-vinylpyridine) (PI-b-PS-b-P2VP) micelles containing HAuCl4 were spin-coated on silicon wafers followed by calcination to form gold nanoparticle arrays. Subsequently the surface optical performances of poly(3-hexylthiophene) (P3HT)-coated Au nanoparticle arrays were investigated. The particle size and the interparticle distance of the gold nanoparticle arrays could be controlled by adjusting the molar ratio of HAuCl4 precursor to vinyl pyridine units in PI-b-PS-b-P2VP and the spin speed during spin-coating. The results demonstrated that Au nanoparticle arrays with large nanoparticle size were able to produce strong electromagnetic field enhancement. Furthermore, the ratio of average particle size to average interparticle distance increased with decreasing spin speed, resulting in strong electromagnetic field enhancement for metal-enhanced fluorescence (MEF) and surface-enhanced Raman scattering (SERS).