Design and synthesis of bio-based amphiphilic polymers of biomedical interest

Due to the increasing antibiotic resistance, which has alarmed the healthcare and agriculture sectors worldwide, there is a growing demand for novel and highly effective antibacterial materials. Amphiphilic copolymers with antibacterial properties have emerged as a promising solution. Among reversible deactivation radical polymerization (RDRP), reversible addition fragmentation chain-transfer (RAFT) polymerization is recognized as the most suitable for synthetizing amphiphilic polymers for biomedical applications. The bactericidal mechanism relies on the activity of both hydrophobic and hydrophilic moieties: initially, the hydrophilic unites, which contain cationic groups, interact electrostatically with the net anionic charges deployed on the outer wall of the bacterial cell membrane. Following this, the hydrophobic groups bind, chelate and penetrate the bacterial cell membrane, leading to cell death and the denaturation of proteins and enzymes. The study is committed to using natural raw materials to develop a more sustainable chemical approach. At first, some bio-based methacrylic monomers, derived from amino acids and tetrahydrogeraniol, were synthetized. Three hydrophilic monomers (Boc-Ala-HEMA, Boc-Phe-HEMA, Boc-Lys-HEMA) were selected. These monomers differ from each other based on the functional groups present in the side chains of their structure. On the other hand, only one monomer was selected (THGA) for the hydrophobic counterpart. Subsequently, linear random copolymers were produced using RAFT polymerization, varying the hydrophilic monomer and the ratio between the two monomer chains to determine which combination yields the best antibacterial effect. All the synthetized materials were analysed and characterised using 1HNMR and all relevant polymer parameters were calculated. Subsequently, the polymers were tested for antibacterial properties against E. coli and S. aureus.