Facile fabrication of P(OVNG-co-NVCL) thermoresponsive double-hydrophilic glycopolymer nanofibers for sustained drug release

Galactose-based polymer-containing phenylboronic acid as carriers for insulin delivery

The galactose-based polymer is a promising drug delivery material. Herein, a new galactose-based block copolymer, termed as 6-O-vinyl sebacic acid-D-galactopyranosyl ester block 3-acrylamide phenylboric acid p(OVNG-b-AAPBA) was successfully synthesized by 'block copolymer' method. The structure of p(OVNG-b-AAPBA) was proved by nuclear magnetic hydrogen spectrum (1 HNMR) and infrared (IR), the thermal stability was observed by thermogravimetric analyzer, and the molecular weights (Mw and Mn) were demonstrated by Gel permeation chromatography (GPC). The above test results suggested that the polymer of p(OVNG-b-AAPBA) was successfully synthesized, and it had optimal molecular weight and thermal stability, which could be used for investigating the drug delivery system. Then, this block copolymer was prepared to the nanoparticle (NP), these NPs had a satisfactory morphology, and their safety was verified by MTT and chronic animal toxicology test. In addition, insulin was encapsulated by the p(OVNG-b-AAPBA) NPs, the drug loading rate and encapsulation efficiency increased with that of AAPBA in the polymer. Finally, this study confirmed that these NPs can effectively maintain the blood sugar of diabetic mice at 96 h. In conclusion, the current study suggested that the insulin-loaded galactose-based polymer-block-3-acrylamide phenylboric acid NPs had slow-release/glucose-responsive drug release performance, which might play an active role in the diabetes therapy.

Development of ferulic acid/cyclodextrin inclusion complex nanofibers for fast-dissolving drug delivery system

Production of electrospun nanofibrous mats of cyclodextrin inclusion complexes with the incorporation of drug molecules would enable promising designing of fast dissolving delivery systems (FDDS) for oral treatments. Here, the single-step electrospinning technique has been applied to prepare cyclodextrin inclusion complex nanofibrous mats (CD-IC NM) of ferulic acid from complete aqueous systems without using any polymeric matrix. The free-standing ferulic acid/CD-IC NM have been electrospun from two different modified cyclodextrin derivatives of hydroxypropyl-beta-cyclodextrin (HP-β-CD) and hydroxypropyl-gamma-cyclodextrin (HP-γ-CD). The initial content of ferulic acid (1/1 ferulic acid/CD (molar ratio) and ~11% (w/w)) has been protected in case of both ferulic acid/CD-IC NM and so the electrospun nanofibrous mats have been fabricated by the ~100% loading efficiency. It has been detected from the in vitro release and disintegration tests that, the amorphous state of ferulic acid based on inclusion complex formation, and the highly porous feature and high surface area of nanofibrous mats have ensured the fast dissolution/release of ferulic acid and disintegration of nanofibrous mats into the liquid medium and artificial saliva. Herein, HP-γ-CD has formed inclusion complexes with ferulic acid more favorably than HP-β-CD and this has leaded to the existence of some un-complexed ferulic acid crystals in ferulic acid/HP-β-CD-IC NM while, ferulic acid has been completely complexed and is in amorphous state in ferulic acid/HP-γ-CD-IC NM. Furthermore, the thermal stability of ferulic acid has been enhanced as an inclusion complexation aid observed by the shift of thermal degradation temperature of ferulic acid from the range of ~120-200 °C to ~140-280 °C.

Synthesis and Self-Assembly of Double-Hydrophilic and Amphiphilic Block Glycopolymers

In this report, we present double-hydrophilic block glycopolymers of poly(2-hydroxyethyl methacrylate)- b-poly(2-(β-glucosyloxy)ethyl methacrylate) (PHEMA- b-PGEMA) and amphiphilic block glycopolymers of poly(ethyl methacrylate)- b-PGEMA (PEMA- b-PGEMA) synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The block glycopolymers were prepared in two compositions of P(H)EMA macro-chain transfer agents (CTAs) and similar molecular weights of PGEMA. Structural analysis of the resulting polymers as well as the conversion of (H)EMA and GEMA monomers were determined by 1H NMR spectroscopy. Size exclusion chromatography measurements confirmed both P(H)EMA macro-CTAs and block glycopolymers had a low dispersity ( Đ ≤ 1.5). The synthesized block glycopolymers had a degree of polymerization and a molecular weight up to 222 and 45.3 kg mol-1, respectively. Both block glycopolymers self-assembled into micellar structures in aqueous solutions as characterized by fluorescence spectroscopy, ultraviolet-visible spectroscopy, and dynamic light scattering experiments.

Galactose-Functionalized Double-Hydrophilic Block Glycopolymers and Their Thermoresponsive Self-Assembly Dynamics

Glycopolymers with large galactose units are attractive in biological processes because of their ability to selectively recognize lectin proteins. Recently, thermoresponsive double-hydrophilic block glycopolymers (TDHBGs) have been designed, which allow sugar residues to expose or hide via the lower critical solution temperature (LCST)-type phase transition. In this work, we first synthesize a new type of TDHBGs, composed of a thermoresponsive poly(di(ethylene glycol)methyl ether methacrylate) block and a galactose-functionalized, poly(6- O-vinyladipoyl-d-galactose) (POVNG) block. The LCST can be tuned by varying the size of the POVNG block. Then, we have systematically investigated their thermoresponsive self-assembly behavior, using static and dynamic light scattering techniques, combined with transmission electron microscopy (TEM) imaging. It is found that the TDHBGs possess both micellization and LCST-type transition, and there exist strong interactions between them, depending on the concentration and structure of the TDHBGs. It is particularly interesting that for the same type of TDHBGs under different conditions, such interactions result in rich morphologies of the formed micelles (or nanoparticles) such as spheres, hollow spheres, prolate ellipsoids, crystal-like, and so on, thus potentially enriching their biological applications by noting that they are hepatoma-targeting glycopolymers.

Thermoresponsive polymeric gel as an on-demand transdermal drug delivery system for pain management

The main aim of this work is to design a heat triggered transdermal drug delivery system (TDDS) using a thermoresponsive polymer, poly (N-vinyl caprolactam) [PNVCL] based gel, where in patients can themselves administer a pulse of drug on mere application of heat pad over the TDDS, whenever pain is experienced. The phase transition temperature of PNVCL was tuned to 35 °C by grafting it onto a pH sensitive biopolymer, Chitosan, to synthesize Chitosan-g-PNVCL (CP) co-polymer which render the gel both thermo- and pH-responsive property. The application of triggered delivery was explored by loading acetamidophenol (a model hydrophilic drug) and etoricoxib (a model hydrophobic drug). In vitro drug release experiments were performed at three different temperatures (25, 32 and 39 °C) at two different pH (5.5 and 7) to study its drug release with response to temperature and pH. Drug release profiles obtained were found to have enhanced release for both the drugs respectively at 39 °C (above LCST) and pH5.5 when compared to other release conditions. In vitro skin permeation of both the drugs performed in rat abdominal skin using Franz diffusion cell showed enhanced drug release when the skin was subjected to higher temperature (39 °C). Moreover, it was also found that skin permeation for hydrophobic drug was better than that of hydrophilic drug. The in vivo biocompatibility studies of the CP gel in rat skin proved that the gel is biocompatible. The results obtained demonstrated the potential use of the thermoresponsive CP gel as an on-demand localized drug delivery system.