2.2. Preparation of Cu–chitosan NPs
Cu–chitosan NPs were prepared based on the ionic gelation of chitosan with TPP anions. Before the completion of cross-linking reaction, CuSO4 (HiMedia, Mumbai, India) solution (0.01%) was added into the formulation. The resulting precipitated nanoparticles were further purified as described earlier [18]. The amount of entrapped Cu ions into nanomaterial was determined by the method described previous [27] with double beam Atomic Absorption Spectrophotometry (AAS4141 model, Electronics Corporation of India Ltd., India).