Electrosprayed Chitosan-Copper Complex Microspheres with Uniform Size

Chitosan-based nano- and microspheres have shown great potential in a broad range of applications, including drug delivery, bone tissue engineering, wastewater treatments, etc. The preparation of uniformly sized spheres with controlled morphology and microstructure is still a challenge. This work investigates the influence of cupric ions (Cu²⁺) on the size, shape, morphology and stability of electrosprayed chitosan-copper (CHT-Cu²⁺) complex microspheres, using chitosans with different degrees of deacetylation. The dynamic viscosity of CHT-Cu²⁺ solutions was measured by Höppler viscometer, while attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was used for the identification of dried microspheres. The size, shape and morphology of microspheres were analyzed by light microscope and scanning electron microscopy (SEM), while stability of dried microspheres was evaluated in different buffer solutions. The volume ratio of wet and dry microspheres was assessed based on the estimated diameter of microspheres. The higher concentration of Cu²⁺ ions resulted in a decrease in viscosity of CHT-Cu²⁺ solutions and volume ratio of prepared microspheres. Changes in the intensities and wave numbers of absorption bands of amino and hydroxyl groups, amide I and amide II suggested that the nitrogen and oxygen atoms in chitosan are coordinating the cupric ions. Micrographs obtained by light microscope and SEM showed that all prepared samples are spherical. The increase of cupric ions concentration changed the topography of microspheres and decreased their size. These results indicated the successful electrospraying of CHT-Cu²⁺ microspheres with uniform size and good stability in aqueous medium.