Typical photoluminescent semiconductor nanoparticles, called quantum dots (QDs), have potential applications in biological labeling. When used to label stem cells, QDs may impair the differentiation capacity of the stem cells. In this study, we synthesized zinc oxide (ZnO) QDs in methanol with an average size of ∼2 nm. We then employed two different types of polyethylene glycol (PEG) molecules (SH-PEG-NH2 and NH2-PEG-NH2) to conjugate ZnO QDs and made them water-dispersible. Fourier transform infrared spectroscopy spectra indicated the attachment of PEG molecules on ZnO QDs. No obvious size alteration was observed for ZnO QDs after PEG conjugation. The water-dispersible ZnO QDs still retained the antibacterial activity and fluorescence intensity. The cytotoxicity evaluation revealed that ZnO QDs at higher concentrations decreased cell viability but were generally safe at 30 ppm or below. Cell lines of hepatocytes (HepG2), osteoblasts (MC3T3-E1) and mesenchymal stem cells (MSCs) were successfully labeled by the water-dispersible ZnO QDs at 30 ppm. The ZnO QD-labeled MSCs maintained their stemness and differentiation capacity. Therefore, we conclude that the water-dispersible ZnO QDs developed in this study have antibacterial activity, low cytotoxicity, and proper labeling efficiency, and can be used to label a variety of cells including stem cells.
Silver nanoparticles (AgNP; many other names such as nanosilver and colloidal silver) have already been used in everyday consumer products requiring broad spectrum antibiotic performance because of their enormous surface area and reactivity. Faunce and Watal [1] recently have critically analyzed the international regulatory issues for medical and domestic use in USA, EU, UK, and Australia. They found that in spite of the fact numerous studies have been made in the past decades, but many scientists are still uncertain of its safety. Very recently, Powers mentioned in her dissertation that her results showed positive that Ag+ and AgNP are developmental neurotoxicants in vitro and in vivo [2]. Therefore, there is a need to conduct a study to identify a global landscape of AgNPs and their products, and their manufacturers. A market- based intellectual property (IP) study has been conducted to examine the current global patent landscape of companies using AgNP in their consumer product development and production from 1980 to 2010. Detailed information in the compositions and formulations is extracted using a "two-stage" stage-gate process from the IP activity in the use of nanosilver. The first stage is in commercial products and the second stage is in consumer products. In the first stage for AgNP and AgNP-based commercial products, there were 7,422 patent families from January 1, 1980 to December 31, 2010. In the second stage for AgNP-based consumer products, 932 patent families from January 1, 1980 to December 31, 2010 were found. Korea, China and USA were found to be the major players in AgNP and AgNP-based commercial and consumer products. However, the recent patenting downturn was observed probably due to rising price in silver metal, regulatory uncertainty, public perception, and health safety & environmental (HS&E) issues.
In order to prepare transparent hybrid films of high refractive index, nanoparticles of TiO2 were prepared and dispersed in a silicone epoxy (SE) resin synthesized from diphenyl silane diol and [2-(3,4-epoxycyclohexyl)ethyl] trimethoxysilane by sol-gel reactions. It was found that amorphous TiO2 nanoparticles of about 5 nm modified with hexahydro-4-methyl phthalic anhydride [HMPA] were dispersed in the SE resin without agglomerations. The refractive index of the hybrids increased linearly with increasing the TiO2 contents. The hybrid containing 30 wt% of the TiO2 particles showed light transmittance of 94% at 450 nm and refractive index of 1.63. The fine dispersion of the TiO2 nanoparticles was attributable to the sol-gel reactions between the SE resin and TiO2 nanoparticles and the modification of the TiO2 particles with HMPA.
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