Thiol-epoxy/thiol-acrylate hybrid networks with systematic variations (100/0, 75/25, 50/50, 25/75, 0/100, w/w) were prepared by free-radical photoinitiator (ITX) and photo-base generator (TBD$HBPh 4 ) induced photopolymerization. The enhanced spectral sensitivity of TBD$HBPh 4 at long wavelengths (320-500 nm) with aid of ITX was capable of in situ generation of a strong base (TBD) to achieve the relatively fast and essentially quantitative thiol-epoxy click reaction. The ITX/TBD$HBPh 4 photoinitiating system, which generated both the free radicals and the strong base upon UV exposure, could induce thiol-epoxy/thiol-acrylate hybrid polymerizations. The kinetics investigated with real-time IR indicated that the thiol-acrylate reactions were faster and more efficient than the thiol-epoxy reactions (>95% conversion in a matter of seconds and minutes, respectively), and the thiol conversion increased with an increase in the epoxy concentration. The incorporation of the thiol-epoxy reaction offered several advantages: the polymerization shrinkage decreased with the increase in the thiolepoxy content due to the low shrinkage factor for the thiol-epoxy system (every mole of epoxy group polymerized produces 6.3 mL of shrinkage). The glass transition temperature of the thiol-epoxy/thiolacrylate hybrid networks progressively increased as a function of the thiol-epoxy content, also resulting in enhanced mechanical and physical properties. This work will be helpful to make optical and electronic devices with low shrinkage and stress, decreased residual monomers, and improved mechanical properties.

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Long-acting topical products for pre-exposure prophylaxis (PrEP) that combine antiretrovirals (ARVs) inhibiting initial stages of infection are highly promising for prevention of HIV sexual transmission. We fabricated core-shell poly(lactide-co-glycolide) (PLGA) nanoparticles, loaded with two potent ARVs, griffithsin (GRFT) and dapivirine (DPV), having different physicochemical properties and specifically targeting the fusion and reverse transcription steps of HIV replication, as a potential long-acting microbicide product. The nanoparticles were evaluated for particle size and zeta potential, drug release, cytotoxicity, cellular uptake and in vitro bioactivity. PLGA nanoparticles, with diameter around 180–200 nm, successfully encapsulated GRFT (45% of initially added) and DPV (70%). Both drugs showed a biphasic release with initial burst phase followed by a sustained release phase. GRFT and DPV nanoparticles were non-toxic and maintained bioactivity (IC50 values of 0.5 nM and 4.7 nM, respectively) in a cell-based assay. The combination of drugs in both unformulated and encapsulated in nanoparticles showed strong synergistic drug activity at 1:1 ratio of IC50 values. This is the first study to co-deliver a protein (GRFT) and a hydrophobic small molecule (DPV) in PLGA nanoparticles as microbicides. Our findings demonstrate that the combination of GRFT and DPV in nanoparticles is highly potent and possess properties critical to the design of a sustained release microbicide.

Based on the use of photopolymerization technology, a facile and reliable method for in situ preparation of silver nanoparticles (AgNPs) within PNIPAAm functional surfaces is presented as a means to achieve non-fouling, antibacterial films. The surface properties were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), water contact angle and thermogravimetric analysis (TGA). The antibacterial and release properties of the surfaces were tested against E. coli: at 37 ˚C (above the LCST of PNIPAAm), the functional films facilitated the attachment of bacteria, which were then killed by the AgNPs. Changing temperature to 4 ˚C (below the LCST), swollen PNIPAAm chains led the release of dead bacteria. The results showed that AgNPs/PNIPAAm hybrid surfaces offer a "smart" antibacterial capability in response to the change of environmental temperature.