title: Effect of PEGylation on the toxicity and permeability enhancement of chitosan.
abstract: The aim of the present work is to investigate if conditions can be devised where PEGylation of chitosan would reduce its toxicity toward the nasal mucosa while maintaining its ability to open the cellular tight junctions and, consequently, produce an enhancement of macromolecular permeability. A series of mPEG-g-chitosan copolymers with varying levels of mPEG substitution, mPEG molecular weight, and chitosan molecular weight were synthesized by grafting carboxylic acid-terminated mPEGs (Mw 1.9 and 5.0 × 10(3) g mol(-1)) to chitosans (Mw 28.9 and 82.0 × 10(3) g mol(-1)) using a NHS/EDC coupling system. The synthesized mPEG-g-chitosans were fully characterized using a number of techniques, including FT-IR, (1)H NMR, and SEC-MALLS and their physicochemical properties were analyzed by TGA and DSC. Thereafter, the conjugates were tested for their cytotoxicity and tight junction modulating property in a relevant cell model, a mucus producing Calu-3 monolayer. mPEG-g-chitosan conjugates exhibited reduced toxicity toward cells, as compared to unmodified chitosan counterparts. Furthermore, the conjugates demonstrated a dramatic effect on cell monolayer transepithelial electrical resistance (TEER) and enhancement of permeability of model macromolecules. TEER and permeability-enhancing effects, as measurable indicators of tight junction modulation, were found to be pH-dependent and were notably more pronounced than those exhibited by unmodified chitosans. This work therefore demonstrates that conditions can be contrived where PEGylation improves the toxicity profile of chitosan, while preserving its effect on epithelial tight junctions in the nose.
authors.affiliation: Drug Delivery and Tissue Engineering Division, School of Pharmacy, and School of Chemistry, University of Nottingham, Nottingham, NG7 2RD, United Kingdom and Critical Pharmaceuticals Limited, BioCity, Pennyfoot Street, Nottingham, NG1 1GF, United Kingdom.
authors.forename: Luca
authors.initials: L
authors.lastname: Casettari
authors.forename: Driton
authors.initials: D
authors.lastname: Vllasaliu
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Mantovani
authors.forename: Steven M
authors.initials: SM
authors.lastname: Howdle
authors.forename: Snow
authors.initials: S
authors.lastname: Stolnik
authors.forename: Lisbeth
authors.initials: L
authors.lastname: Illum
mesh_terms: D002463:Cell Membrane Permeability / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D048271:Chitosan / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D015394:Molecular Structure; D011092:Polyethylene Glycols / Q000737:chemistry*; D012995:Solubility; D013329:Structure-Activity Relationship
chemical_list: D011092:Polyethylene Glycols; D048271:Chitosan