Recent Advancements on Photothermal Conversion and Antibacterial Applications over MXenes-Based Materials

Abstract

As a global problem, uncontrollable harmful bacterial proliferation has posed great threat to public health, which eventually caused economic burdens to the infected patients and the whole society [ 1 , 2 ]. The infectious bacteria always brought in wound infections [ 3 , 4 ], disease transmission [ 5 , 6 ], water contamination [ 7 ], soil contamination [ 8 ], and widespread corrosions [ 9 ]. From a traditional viewpoint, antibiotics have held the top priority in the eradication of bacterial growth. Nevertheless, the emergence of antibiotic-resistant pathogens due to antibiotic abuse results in the failure of antibiotic therapy, becoming one of the most significant global challenges [ 10 ]. The drug-resistant bacteria have developed penetration barriers, drug efflux pumps, inactivating enzymes to protect themselves from the developed antibiotics [ 11 , 12 ]. In addition, bacteria could also shelter from the attack of drugs or harsh conditions by forming the biofilm, a structure that serves as a sanctuary of the inner cells [ 13 , 14 ]. Besides, horizontal gene transfer can disseminate resistance genes among biofilm wrapped bacteria, amplifying the bacterial resistance [ 15 ]. Unquestionably, the emergence of drug-resistant bacterial and the formation of biofilms leads to the dreadful biological crisis. Thus, searching for novel efficient treatment approaches without inducing drug resistance is of great significance for solving these issues. Recently, non-invasive photothermal therapy (PTT) functioning under light irradiation represents a promising alternative to antibiotics in the fight against bacterial proliferation [ 16 , 17 ]. Based on hyperthermia beyond tolerance, this kind of therapy could efficiently damage the integrity of pathogenic bacteria in a controllable manner [ 18 ]. Furthermore, bacteria were unlikely to develop resistance to PTT as they did to antibiotics by drug excretion, facilitating metabolism and postponing absorption [ 11 , 19 ]. In the PTT process, hyperthermia originating from the photo-to-thermal conversion process on the PTT agents could cause protein denaturation and inactivation, deoxyribonucleic acid (DNA) cross-linking and cell membrane loosening, which also facilitates the penetration of other available antibacterial agents to destroy the biofilm structure [ 20 ]. These satisfactory properties of PTT exhibit the feasibilities of using antibiotics-independent techniques to destroy harmful bacteria, thereby attracting extensive attention. To achieve desirable antibacterial efficiency and less light energy consumption, synergistic tactics by combining PTT with other techniques, such as photodynamic therapy (PDT) and metal ions incursion, have been brought into focus [ 21 , 22 , 23 ]. The heat generated by PTT could tremendously enhance the permeability of the bacteria membranes and promote the intracellular permeation of reactive oxygen species (ROS) or metal ions [ 24 ]. These synergistic tactics could not only lower the dosage requirements of photothermal agents, but also offset the imperfections of other therapies. In the post-antibiotic era, their high therapeutic efficiency has been proved, and it is considered safer and more thriving representatives in the field of antibacterial applications [ 21 , 25 , 26 ].