Amphiphilic chitosan derivative-based core–shell micelles: Synthesis, characterisation and properties for sustained release of Vitamin D3

•A novel amphiphilic chitosan derivative (DCMCs) with hydrophilic carboxyl and hydrophobic hexadecyl groups was synthesised.•DCMCs can form core–shell micelles by self-assemble in water solution with low critical micelle concentration.•Vitamin D3 was initially applied to load into DCMCs core–shell micelles.•The solubility and stability of Vitamin D3 were improved greatly. Novel amphiphilic chitosan derivative of N,N-dimethylhexadecyl carboxymethyl chitosan (DCMCs) was synthesised. The physical properties of DCMCs were characterised by Fourier transform-infrared spectroscopy, nuclear magnetic resonance spectroscopy, X-ray diffraction and differential scanning calorimetry. DCMCs can form core–shell micelles with low critical micelle concentration (31mgL−1). The core–shell micelles exhibited spherical shape with positive charge (+50.7mV) and narrow size distribution (polydispersity index