Hypoxia-Sensitive Zwitterionic Vehicle for Tumor-Specific Drug Delivery through Antifouling-Based Stable Biotransport Alongside PDT-Sensitized Controlled Release.

A hypoxia-sensitive zwitterionic vehicle, DHigh-PEI-(A+P), with the ability for antifouling-mediated, stable biotransport and a photodynamic therapy (PDT)-sensitized hypoxic response for spatiotemporal controlled drug release, was developed for the tumor-specific delivery of chemotherapeutics and biomacromolecules. The amphiphilic DHigh-PEI-(A+P) was constructed from a betaine monomer (DMAAPS), a photosensitizer (PpIX), and an azobenzene-4,4'-dicarboxylic acid-modified polyethylenimine. Herein paclitaxel (PTX) was selected as a common model drug to verify the functions of the designed polymer. First, DHigh-PEI-(A+P) was demonstrated to spontaneously coassemble with PTX in aqueous solution with high drug loading (>35%). The desirable antifouling ability of DHigh-PEI-(A+P) was independently verified by efficient 4T1 endocytosis in serum alongside systemic tumor targeting. Furthermore, PpIX-mediated PDT was verified to aggravate and homogenize a hypoxic microenvironment at the cell and tissue levels for a sharp responsive disassembly of DHigh-PEI-(A+P) and thus a robust drug release in a well-controlled manner. As a result, DHigh-PEI-(A+P) amplified the therapeutic outcome of PTX on orthotopic 4T1 mouse models with minimal collateral damage. We proposed that DHigh-PEI-(A+P) may serve as a tailor-designed universal vehicle for the tumor-specific delivery of drugs with distinct physicochemical properties.

The efficiency and mechanism of N-octyl-O, N-carboxymethyl chitosan-based micelles to enhance the oral absorption of silybin.

This study demonstrates the preparation of a silybin-loaded N-octyl-O, N-carboxymethyl chitosan micelle (OCC-SLB) to enhance the oral absorption efficiency of silybin (SLB) and investigate the related mechanisms of enhancement. Firstly, the physicochemical properties of OCC and OCC-SLB micelles, including critical micelle concentration (CMC), particle size, zeta potential, drug-loading, etc., were determined. Results of pharmacokinetic studies on rats then confirmed a desirable enhancement in the oral bioavailability of SLB by OCC-SLB micelles compared with a stock SLB suspension solution. Subsequently, uptake studies on the Caco-2 cell line demonstrated that OCC-SLB micelles effectively accumulated SLB or rhodamine-123 into cells through clathrin and caveolae-mediated endocytosis and the inhibition of P-glycoprotein (P-gp) efflux. In addition, results of the Caco-2 transport study further clarified that OCC-SLB micelles enhanced the permeability of SLB via tight junction opening and clathrin-mediated transcytosis across the endothelium. These findings indicated the OCC micelle platform as a potential delivery vehicle for oral administration of P-gp substrates such as SLB.