A hybrid genipin-crosslinked dual-sensitive hydrogel/nanostructured lipid carrier ocular drug delivery platform

The objective of this study was to develop a novel hybrid genipin-crosslinked dual-sensitive hydrogel/nanostructured lipid carrier(NLC) drug delivery platform. An ophthalmic antiinflammatory drug, baicalin(BN) was chosen as the model drug. BN –NLC was prepared using melt-emulsification combined with ultra-sonication technique. Additionally, a dual pH-and thermo-sensitive hydrogel composed of carboxymethyl chitosan(CMCS) and poloxamer 407(F127) was fabricated by a cross-linking reaction with a nontoxic crosslinker genipin(GP). GP-CMCS/F127 hydrogel was characterized by FTIR, NMR, XRD and SEM. The swelling studies showed GP-CMCS/F127 hydrogel was both pH-and thermo-sensitive. The results of in vitro release suggested BN –NLC gel can prolong the release of baicalin comparing with BN eye drops and BN –NLC. Ex vivo cornea permeation study was evaluated using Franz diffusion cells. The apparent permeability coefficient(Papp) of BN –NLC gel was much higher(4.46-fold) than that of BN eye drops. Through the determination of corneal hydration levels, BN –NLC gel was confirmed that had no significant irritation to cornea. Ex vivo precorneal retention experiments were carried out by a flow-through approach. The results indicated that the NLC-based hydrogel can prolong precorneal residence time. In conclusion, the hybrid NLCbased hydrogel has a promising potential for application in ocular drug delivery.

Recent Advances in Cadmium Sulfide-Based Photocatalysts for Photocatalytic Hydrogen Evolution

High-efficiency photocatalytic hydrogen evolution(PHE)relies on the development of inexpensive,stable,and efficient photocatalysts.Cadmium sulfide(CdS),as a typical binary metal sulfide,has attracted considerable research attention due to its negative conduction band position,narrow band gap for visible-light response,and strong driving force for PHE.However,the construction of CdSbased photocatalysts and the PHE rate still require improvement for practical applications.In this review,recent advances in CdS-based photocatalysts for PHE via water splitting are systematically summarized.First,the semiconductor properties of CdS,including the crystal and band structures,are briefly introduced.Afterward,the fundamental mechanisms of PHE using semiconductor photocatalysts via water splitting are discussed.Subsequently,the photoactivity of bare CdS with different morphologies and structures,CdS with cocatalyst loading,and CdS-based heterojunction photocatalysts are reviewed and discussed in detail.Finally,the challenges and prospects for exploring advanced CdS-based photocatalysts are provided.