title: Hypromellose-graft-chitosan and Its Polyelectrolyte Complex as Novel Systems for Sustained Drug Delivery.
abstract: Polyelectrolyte complexes formed between chitosan (CS) and anionic polymers have attracted increasing interest in drug delivery. In this study, CS is copolymerized with hypromellose via a coupling reagent-mediated approach to form a water-soluble, nontoxic CS derivative, namely hypromellose-graft-CS (HC), which is subsequently complexed with carboxymethylcellulose (CMC) to generate a polyampholytic hydrogel. When compared with conventional CS, HC is highly water-soluble across a wide pH range, and has a substantially higher pH buffering capacity to provide a pH-stable environment for delivery of drugs. In addition, the polyelectrolyte complex of HC exhibits a drug encapsulation efficiency of over 90% in all drugs tested, which is 1-2 fold higher than the efficiency attainable by the polyelectrolyte complex of conventional CS, with a 2-3 fold longer duration of sustained drug release. Our results indicate that as a novel polymer, HC has excellent promise for future pharmaceutical applications.
authors.affiliation: †Department of Mechanical Engineering, The University of Hong Kong, Hong Kong Special Administrative Region, China.
authors.forename: Wing-Fu
authors.initials: WF
authors.lastname: Lai
authors.affiliation: †Department of Mechanical Engineering, The University of Hong Kong, Hong Kong Special Administrative Region, China.|‡HKU-Shenzhen Institute of Research and Innovation, Shenzhen, Guangdong 518000, China.
authors.forename: Ho Cheung
authors.initials: HC
authors.lastname: Shum
mesh_terms: D048271:Chitosan / Q000737:chemistry*; D003692:Delayed-Action Preparations / Q000737:chemistry*; D004058:Diffusion; D004573:Electrolytes / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D065347:Hypromellose Derivatives / Q000737:chemistry*; D053769:Nanocapsules / Q000008:administration & dosage / Q000737:chemistry* / Q000648:ultrastructure; D058726:Nanoconjugates / Q000008:administration & dosage / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D004364:Pharmaceutical Preparations / Q000008:administration & dosage / Q000737:chemistry*; D012995:Solubility
chemical_list: D003692:Delayed-Action Preparations; D004573:Electrolytes; D053769:Nanocapsules; D058726:Nanoconjugates; D004364:Pharmaceutical Preparations; D065347:Hypromellose Derivatives; D048271:Chitosan
keywords: chitosan; drug delivery; drug release; hypromellose; polyelectrolyte complex