Tailoring the network properties of Ca2+ crosslinked Aloe vera polysaccharide hydrogels for in situ release of therapeutic agents.

Properties of Aloe vera galacturonate hydrogels formed via Ca(2+) crosslinking have been studied in regard to key parameters influencing gel formation including molecular weight, ionic strength, and molar ratio of Ca(2+) to COO(-) functionality. Dynamic oscillatory rheology and pulsed field gradient NMR (PFG-NMR) studies have been conducted on hydrogels formed at specified Ca(2+) concentrations in the presence and absence of Na(+) and K(+) ions in order to assess the feasibility of in situ gelation for controlled delivery of therapeutics. Aqueous Ca(2+) concentrations similar to those present in nasal and subcutaneous fluids induce the formation of elastic Aloe vera polysaccharide (AvP) hydrogel networks.

Structural characterization and solution properties of a galacturonate polysaccharide derived from Aloe vera capable of in situ gelation.

A series of highly purified galacturonate polysaccharides have been extracted from the Aloe vera plant and analyzed in terms of chemical composition and molecular weight. This Aloe vera polysaccharide (AvP) has been found to exist as a high molecular weight species and possess a unique chemical composition, including a high galacturonic acid (GalA) content and low degree of methyl ester substitution. These factors facilitate gel formation upon exposure to low concentrations of calcium ions, leading to potential application in formulations designed for in situ nasal or subcutaneous protein delivery.

Thermoreversible hydrogels from RAFT-synthesized BAB triblock copolymers: steps toward biomimetic matrices for tissue regeneration.

Narrowly dispersed, temperature-responsive BAB block copolymers capable of forming physical gels under physiological conditions were synthesized via aqueous reversible addition fragmentation chain transfer (RAFT) polymerization. The use of a difunctional trithiocarbonate facilitates the two-step synthesis of BAB copolymers with symmetrical outer blocks. The outer B blocks of the triblock copolymers consist of poly(N-isopropylacrylamide) (PNIPAM) and the inner A block consists of poly(N,N-dimethylacrylamide).