Synthesis of poly(2-hydroxyethyl methacrylate)-grafted poly(aminoamide) dendrimers as polymeric nanostructures

Fourth-generation poly(aminoamide) (PAMAM) dendrimer was synthesized via a divergent method with iterative sequence Michael addition or alkylation and amidation reactions with ethylenediamine as primary core and methyl acrylate. Then, its peripheral primary amine groups were conjugated with S-(thiobenzoyl)thioglycolic acid as reversible addition-fragmentation chain transfer (RAFT) agent and poly(2-hydroxyethyl methacrylate) (P(HEMA)) was grafted onto surface via RAFT polymerization. Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR), and dynamic light scattering (DLS) were used to approve the successful synthesis of different nanostructures. Then, fourth-generation, RAFT-conjugated fourth-generation, and P(HEMA)-grafted fourth-generation PAMAM dendrimers were examined as stimuli-responsive nanostructures. Finally, in vitro cellular cytotoxicity was applied to evaluate the biocompatibility of synthesized dendrimers and investigate the cytotoxic effect of grafted polymer using HeLa cells. As a results, fourth-generation and RAFT-conjugated fourth-generation samples showed no stimuli-responsive behavior while P(HEMA)-grafted fourth-generation PAMAM dendrimer had a LCST of 26 °C. Also, fourth-generation and RAFT-conjugated fourth-generation samples were characterized as toxic compounds while grafting P(HEMA) decreased cytotoxicity significantly.