Preparation and characterization of radical and pH-responsive chitosan-gallic acid conjugate drug carriers

A novel chitosan-based nanoparticle carrier was prepared in this study. The chitosan derivative, N,O-carboxymethylchitosan (NOCC) was reacted with gallic acid (GA) using a non-toxic water-soluble carbodiimide to obtain the NOCC-GA conjugate, and the chemical structure of the conjugate was characterized with FT-IR and NMR spectra. The antioxidant activity of the NOCC-GA conjugate was examined by DPPH and ABTS⁺ radical scavenging activity. The radical/pH-responsive properties of the NOCC-GA conjugate and its iron(II) complex were examined by fluorescence spectral and light transmittance studies. The mean particle sizes of the NOCC-GA conjugate and its iron(II) complex nanoparticles were determined by a light scattering method. The NOCC-GA conjugate and its iron(II) complex nanoparticles might provide a novel way to deliver antioxidative protein or natural products in future.