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This study was conducted to develop formulations of hydrocortisone butyrate (HB)-loaded poly(D,L-lactic-co-glycolic acid) nanoparticles (PLGA NP) suspended in thermosensitive gel to improve ocular bioavailability of HB for the treatment of bacterial corneal keratitis. PLGA NP with different surfactants such as polyvinyl alcohol (PVA), pluronic F-108, and chitosan were prepared using oil-in-water (O/W) emulsion evaporation technique. NP were characterized with respect to particle size, entrapment efficiency, polydispersity, drug loading, surface morphology, zeta potential, and crystallinity. In vitro release of HB from NP showed a biphasic release pattern with an initial burst phase followed by a sustained phase. Such burst effect was completely eliminated when nanoparticles were suspended in thermosensitive gels and zero-order release kinetics was observed. In HCEC cell line, chitosan-emulsified NP showed the highest cellular uptake efficiency over PVA- and pluronic-emulsified NP (59.09 ± 6.21%, 55.74 ± 6.26%, and 62.54 ± 3.30%, respectively) after 4 h. However, chitosan-emulsified NP indicated significant cytotoxicity of 200 and 500 μg/mL after 48 h, while PVA- and pluronic-emulsified NP exhibited no significant cytotoxicity. PLGA NP dispersed in thermosensitive gels can be considered as a promising drug delivery system for the treatment of anterior eye diseases.

Excessive price and scarcity of Pt species make it very necessary to enhance the atom utilization and catalytic efficiency of Pt catalysts for implementing their industrial practicality. Here, natural cotton is adopted as the precursor to in-situ support well-dispersed and uniform-sized Ni nanoparticles, which then work as nanoislands to effectively deposit single-atom Pt via the galvanic replacement reaction. On the resulting fibrous carbon matrix, the monocrystalline Ni particles are verified to tightly anchor isolated Pt atoms to form the alloyed PtNi nanoparticles. In the 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP), the catalytic activity of the bimetallic PtNi/C catalyst with the low Pt loading (0.81%) maximally reaches 25 times as high as the primary Ni/C product. Simulated calculations demonstrate that the single-atom Pt centers on PtNi nanoparticles rapidly capture and split H 2 molecules, while Ni atoms strongly adsorb 4-NP molecule to activate the -NO 2 group. Therefore, the trapped H atom could easily attack the -NO 2 and reduce 4-NP. Cotton is utilized to in-situ prepare well-dispersed and uniform-sized PtNi/C bimetallic catalysts with the superior activity in the 4-nitrophenol reduction. [Display omitted] • Natural cotton has been utilized for fabricating the Ni/C catalyst. • Ni nanoparticles work as nanoislands to deposit single-Atom Pt, forming PtNi nanoparticles. • The PtNi/C catalyst exhibits a great catalytic performance for reduction of 4-NP. • Catalytic mechanism of the PtNi/C bimetallic catalyst has been explored. [ABSTRACT FROM AUTHOR]