Synthesis and evaluation of mucoadhesive acryloyl-quaternized PDMAEMA nanogels for ocular drug delivery

Poly((2-dimethylamino)ethyl methacrylate) (PDMAEMA) nanogels were synthesized via surfactant-free free-radical polymerization technique in aqueous conditions utilizing N,N’-methylene-bis-acrylamide (MBA) as a crosslinking agent. The PDMAEMA nanogels were subsequently quaternized with acryloyl chloride in order to yield mucoadhesive materials which incorporate two mucoadhesive concepts; electrostatic interactions and covalent bond forming acrylate groups. The native PDMAEMA nanogels were found to exhibit good mucoadhesive properties on ex vivo bovine conjunctival tissues, which was found to increase proportionally with the degree of quaternization. With a view to determine the ocular drug delivery capabilities of the materials, both quaternized and native nanogels were loaded with pilocarpine hydrochloride via an absorption method, and their in vitro release profiles were analysed. The nanogels were found to exhibit a high loading capacity (>20% of total weight) and a sustained release over 6 h

Block copolymer materials from the organocatalytic ring-opening polymerization of a pentaerythritol-derived cyclic carbonate

9-Phenyl-2,4,8,10-tetraoxaspiro[5,5]undecanone (PTO) was synthesized from pentaerythritol via the acid-catalyzed acetal formation reaction with benzaldehyde and subsequent ring closure with ethyl chloroformate. The cyclic carbonate monomer was subsequently polymerized by ring-opening polymerization (ROP) initiated from 1,4-butanediol (1,4-BDO) using the 1-(3,5-bis(trifluoromethyl)phenyl)-3-cyclohexylthiourea and 1,8-diazabicyclo[5.4.0]undec-7-ene dual organocatalytic system. It was found that the organocatalyst allowed for the synthesis of well-defined polymers with minimal adverse side reactions and low dispersities. This system was then employed in the ROP of PTO initiated from an α,ω-dihydroxy poly(caprolactone) (PCL) macroinitiator, with varying molecular weights, to yield a series of A-B-A block copolymers. These materials were characterized by 1H NMR spectroscopy, gel permeation chromatography, differential scanning calorimetry, thermogravimetric analysis and tensile analysis. It was found that the chain extension from PCL with poly(PTO) (PPTO) blocks yielded a thermoplastic material with superior tensile properties (elongation and Young's modulus) to that of the PCL homopolymer. Furthermore, it was noted that the addition of PPTO could be employed to alter the crystallization properties (crystallization temperature (Tc), and percentage crystallization) of the central PCL block. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2279–228