Preparation of chitosan self-aggregates as a gene delivery system

• Published in: Journal of controlled release 1998-02, Vol.51 (2), p.213-220
• Main Authors: Lee, K.Y, Kwon, I.C, Kim, Y.-H, Jo, W.H, Jeong, S.Y
• Format: Article
• Language: English
• Subjects: Biocompatible Materials - chemistry; Biological and medical sciences; Cell Line; Cell transfection; Charge complex; Chitin - analogs & derivatives; Chitin - chemistry; Chitosan; Chitosan self-aggregate; Chloramphenicol O-Acetyltransferase - analysis; Deoxycholic Acid; DNA, Bacterial - chemistry; Escherichia coli - enzymology; Fluorescent Dyes - analysis; Gene Transfer Techniques; General pharmacology; Glucose; Hydrogen-Ion Concentration; Hydrophobic modification; Medical sciences; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Plasmid DNA; Plasmids; Spectrometry, Fluorescence; Transfection
• ISSN: 0168-3659; 1873-4995
• DOI: 10.1016/S0168-3659(97)00173-9

Hydrophobically modified chitosan containing 5.1 deoxycholic acid groups per 100 anhydroglucose units was synthesized by an EDC-mediated coupling reaction. Formation and characteristics of self-aggregates of hydrophobically modified chitosan were studied by fluorescence spectroscopy and dynamic light scattering method. The critical aggregation concentration (cac) of the self-aggregate was determined by measuring the fluorescence intensity of pyrene as a fluorescent probe. The cac value in PBS solution (pH 7.2) was 1.7×10 −2 mg/ml. Mean diameter of self-aggregates in PBS solution (pH 7.2) was 162±18 nm with an unimodal size distribution. Charge complex formation between self-aggregates and plasmid DNA was confirmed by electrophoresis on an agarose gel. Migration of DNA on an agarose gel was completely retarded above a charge ratio (+/−) of 4/1 at pH 7.2. The free DNA dissociated from the complexes was observed by electrophoresis above pH 8.0 at a fixed charge ratio of 4/1. An efficient transfection of COS-1 cells was achieved by self-aggregates/DNA complexes.