Preparation and charaterization of self-assembled nanoparticles based on linolenic-acid modified chitosan

Chitosan was modified by conjugating coupling with linolenic acid through the l-ethyl-3-(3-dimethylaminopropyyl) carbodiimide (EDC)-mediated reaction. The degree of substitution 1.8% (i.e. 1.8 linolenic acid group per 100 anhydroglucose units) was measured by ¹H NMR. The critical aggregation concentration (CAC) of the self-aggregate of hydrophobically modified chitosan was determined by measuring the fluorescence intensity of the pyrene as a fluorescent probe. The CAC value in phosphate-buffered saline (PBS) solution (pH7.4) was 5 × 10⁻² mgmL⁻¹. The average particle size of self- aggregates of hydrophobically modified chitosan in PBS solution (pH7.4) was 210.8 nm with a unimodal size distribution ranging from 100 to 500 nm. Transmission electron microscopy (TEM) study showed that the formation of near spherical shape nanoparticles has enough structural integrity. The loading ability of hydrophibically modified chitosan (LA-chitosan) was investigated by using bovine serum albumin (BSA) as the model. The loading capacity of self-aggregated nanoparticles increases (19.85% ±0.04% to 37.57% ±0.25%) with the concentration of BSA (O.l–O.5 mgmL⁻¹)