The Synthesis Of Photothermal Nanomaterials And Their Applications As Antibacterial Agents

In recent years,the functions of antibiotics have been greatly restricted due to the emergence of drug-resistant strains which seriously threatens human life.Therefore,there is an extremely urgent need to develop new kinds of effective antibacterial agents.With the rapid development of nanotechnology,many groups have developed a variety of novel nano-antibacterial materials,and have made gratifying progress in the antibacterial field.In recent years,photothermal therapy(PTT)has developed rapidlybecause of its unique advantages of high efficiency and no resistance.Based on this,two new types of antibacterial nanomaterials were designed and synthesized for the treatment of Staphylococcus aureus(S.aureus),which is common bacteria for nosocomial infection.The work could be divided into the following two parts:We developed two kinds of GA-Fe nanoparticles(GA-Fe NPs),which were synthesized by coordinating Fe2+ and Fe3+ with the natural antibacterial molecule gallic acid(GA).The two kinds of resulting GA-Fe NPs showed extremely similar morphology,exhibiting good hyperthermic effects,and were much more stable than GA in physiological environment,due to coordination by iron ions.In terms of antibacterial abilities,the results demonstrated that the coordination of Fe ions allowed for improvements in the antibacterial activity of GA.Antibacterial effects of GA-Fe NPs were also significantly better than GA solution and at the same dose,GA-Fe(?)NPs showed stronger antibacterial effects.Besides that,almost all the bacteria was killed by GA-Fe NPs with laser irradiation.At low doses the antibacterial activity of GA-Fe NPs were unsatisfactory.Thus,Cu2Se nanosheets(Cu2Se NSs)were next synthesized by an anion exchange method.The obtained Cu2Se NSs exhibit strong absorption in NIR ? window and outstanding photothermal conversion efficiency at 61.16%,while also presenting good biocompatibility.The results of antibacterial experiments in vitro showed the dual-antibacterial effects of Cu2Se NSs.When treated with 40 ?g/mL Cu2Se NSs,the bacterial growth would be noticeably inhibited;in addition,the bacteria inacti vation percentages could be over 99.9%after combining laser irradiation.Besides that,Cu2Se NSs were also used as a photothermal agent for abscess treatment,which showed that over 90%bacterial cells were kill by PTT in abscess area,demonstrating the potential of Cu2Se NSs as antibacterial agents for abscess treatment.In summary,we have synthesized two types of antibacterial materials,including GA-Fe NPs and Cu2Se NSs,and exploring the basic properties and antibacterial effects.The strategies of combining PTT and GA-Fe NPs/Cu2Se NSs were available from our previous work,which provided an interesting reference for the development new antibacterial nanomaterials.