Preparation of nanogels based on kappa-carrageenan/chitosan and N-doped carbon dots: study of drug delivery behavior

In this study, new pH-sensitive nanogels containing rivastigmine as a model drug were synthesized by graft polymerization of Acrylamid/Sodium Acrylate monomers onto chitosan (CS) and kappa-carrageenan (CG or κ-carrageenan) backbone in the presence of N, N'-Methylenebisacrylamide (MBA) as cross-linker, nitrogen-doped carbon dots (N-CDs) and ammonium persulfate as an initiator. The prepared nanogels were characterized by FE-SEM, XRD, FTIR, EDX and TGA techniques. The swelling behavior of the nanogels was affected by MBA content, monomer content, amount of CG or CS, and pH in the synthesis. The nanogels exhibited well pH-sensitivity during drug release investigation under simulated gastric (< 61% at pH 1.2) and intestinal (~ 95% at pH 7.4) media. The cytotoxicity test was investigated on human fibroblast cells using MTT assay. The results indicated that cell survival rate was more than 88% in < 62.5 μg/mL concentration of nanogels. Incorporating of N-CDs in the nanogel network increased the swelling capacity, entrapment efficiency, and ensuring the controlled release of the entrapped drug. In this work, we were able to enhance the properties of drug-loaded chitosan nanogels in pH 7.4.