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In this study, biocompatible and proton-resistant CdSe quantum dots (QDs) assembled on gelatin nanospheres (GNs) have been synthesized by combining the two-step desolvation method with the layer-by-layer assembly technique. The core-shell fluorescent gelatin nanosphere consists of a gelatin core and a four-layer shell of hydrophilic CdSe QDs assembled through polyelectrolytes (PE). The morphology, microstructures, and photostability of the hybrid spheres were further investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), fluorospectrometery, and confocal fluorescent microscopy (CFM), respectively. The average diameter of the hybrid QDs-gelatin nanospheres (QDs-GNs) is estimated at 484 ± 40 nm. Our results indicate that the 20 ± 5 nm of the shell is attributed to the four-layer of CdSe QDs assembled through the PE. QD-GNs show a strong photoluminescence with the maximum emission (λ(em)) at 613 nm at the excitation wavelength of 470 nm. The core-shell QDs-GNs are able to resist quenching in acidic solution (pH < 4). Furthermore, core-shell QDs-GNs show a longer lifetime in a broad range of pH values, from 9 to 1. The calculated average lifetime (τ(ave)) of QDs-GNs is about 889 ± 23 ps, which is 3-fold longer than that of MUA-QDs (263 ± 10 ps) at pH 7.0. The enhanced lifetime of QDs-GNs is almost 9 times of that of CdSe QDs when pH value is 1. Meanwhile, the cell viability study shows that no significant toxic effect is imposed on the NIH/3T3 mouse fibroblast cell line when the concentration of QD-GNs is below 5 mg/mL. It is expected that this new biocompatible fluorescent nanospheres could be an excellent alternative fluorescent imaging agent for cell labeling, especially in acidic conditions.

Silicone hydrogel used as contact lens is deposited a nanocomposite coating by a matrix assisted pulsed laser evaporation (MAPLE), which can protect eyes from UV exposure, and against bacterial contamination.

Surface and interface modifications of synthetic silicone hydrogels used for wearable and implantable medical devices, e.g. catheters and contact lenses, are critical to overcome their poor mechanical properties and biofouling. In this paper, silica nanoparticles (SiO 2 NPs) were incorporated within silicone hydrogels through photo-polymerization. As compared to the silicone hydrogel, the nanocomposited silicone hydrogel shows highly textured microstructures, increased swelling behaviour and improved stiffness. Meanwhile, a hydrophilic surface of silicone hydrogel is important to minimize protein fouling which forms a conditioning layer for the growth of bacterial biofilm. Here, we applied matrix-assisted pulsed laser evaporation (MAPLE) with a pulsed Nd:YAG laser at 532 nm to deposit polyethylene glycol (PEG) on the surface of the nanocomposited silicone hydrogels. The PEG deposited on the nanocomposited silicone hydrogels forms islands at the submicron-scale, which increase with increasing irradiation time (t).The protein adsorption on nanocomposited silicone hydrogel with PEG deposition decreases over 40 AE 2% when t = 2 h. Compared to the commercial silicone catheters, the nanocomposited silicone hydrogel with PEG deposition can reduce the growth of bacteria from 1.20 Â 10 6 CFU cm À2 to 3.69 Â 10 5 CFU cm À2 .In addition, the relative cell viabilities of NIH/3T3 mouse fibroblast cells treated using the nanocomposited silicone hydrogels coated with/without PEG were studied. No toxic effect is imposed on the cells.Consequently, the MAPLE process is a controllable, contamination-free technique to modify the surface of silicone hydrogels. We expect that the nanocomposited silicone hydrogels with appropriate surface treatment can be applied in various wearable and implantable medical devices.

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