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.