Nanomaterials-Enabled Physicochemical Antibacterial Therapeutics: Toward the Antibiotic-Free Disinfections

Metal-Organic Framework Based Mucoadhesive Nanodrugs for Multifunction Helicobacter Pylori Targeted Eradication, Inflammation Regulation and Gut Flora Protection

The prevalence of drug-resistant bacteria presents a significant challenge to the antibiotic treatment of Helicobacter pylori (H. pylori), while traditional antimicrobial agents often suffer from shortcomings such as poor gastric retention, inadequate alleviation of inflammation, and significant adverse effects on the gut microbiota. Here, a selenized chitosan (CS-Se) modified bismuth-based metal-organic framework (Bi-MOF@CS-Se) nanodrug is reported that can target mucin through the charge interaction of the outer CS-Se layer to achieve mucosal adhesion and gastric retention. Additionally, the Bi-MOF@CS-Se can respond to gastric acid and pepsin degradation, and the exposed Bi-MOF exhibits excellent antibacterial properties against standard H. pylori as well as clinical antibiotic-resistant strains. Remarkably, the Bi-MOF@CS-Se effectively alleviates inflammation and excessive oxidative stress by regulating the expression of inflammatory factors and the production of reactive oxygen species (ROS), thereby exerting therapeutic effects against H. pylori infection. Importantly, this Bi-MOF@CS-Se nanodrug does not affect the homeostasis of gut microbiota, providing a promising strategy for efficient and safe treatment of H. pylori infection.

Supramolecular Assembly Based on Calix(4)arene and Aggregation-Induced Emission Photosensitizer for Phototherapy of Drug-Resistant Bacteria and Skin Flap Transplantation

Photodynamic therapy as a burgeoning and non-invasive theranostic technique has drawn great attention in the field of antibacterial treatment but often encounters undesired phototoxicity of photosensitizers during systemic circulation. Herein, a supramolecular substitution strategy is proposed for phototherapy of drug-resistant bacteria and skin flap repair by using macrocyclic p-sulfonatocalix(4)arene (SC4A) as a host, and two cationic aggregation-induced emission luminogens (AIEgens), namely TPE-QAS and TPE-2QAS, bearing quaternary ammonium group(s) as guests. Through host-guest assembly, the obtained complex exhibits obvious blue fluorescence in the solution due to the restriction of free motion of AIEgens and drastically inhibits efficient type I ROS generation. Then, upon the addition of another guest 4,4'-benzidine dihydrochloride, TPE-QAS can be competitively replaced from the cavity of SC4A to restore its pristine ROS efficiency and photoactivity in aqueous solution. The dissociative TPE-QAS shows a high bacterial binding ability with an efficient treatment for methicillin-resistant Staphylococcus aureus (MRSA) in dark and light irradiation. Meanwhile, it also exhibits an improved survival rate for MRSA-infected skin flap transplantation and largely accelerates the healing process. Thus, such cascaded host-guest assembly is an ideal platform for phototheranostics research.

Antibacterial micro/nanomotors: advancing biofilm research to support medical applications

Multi-drug resistant (MDR) bacterial infections are gradually increasing in the global scope, causing a serious burden to patients and society. The formation of bacterial biofilms, which is one of the key reasons for antibiotic resistance, blocks antibiotic penetration by forming a physical barrier. Nano/micro motors (MNMs) are micro-/nanoscale devices capable of performing complex tasks in the bacterial microenvironment by transforming various energy sources (including chemical fuels or external physical fields) into mechanical motion or actuation. This autonomous movement provides significant advantages in breaking through biological barriers and accelerating drug diffusion. In recent years, MNMs with high penetrating power have been used as carriers of antibiotics to overcome bacterial biofilms, enabling efficient drug delivery and improving the therapeutic effectiveness of MDR bacterial infections. Additionally, non-antibiotic antibacterial strategies based on nanomaterials, such as photothermal therapy and photodynamic therapy, are continuously being developed due to their non-invasive nature, high effectiveness, and non-induction of resistance. Therefore, multifunctional MNMs have broad prospects in the treatment of MDR bacterial infections. This review discusses the performance of MNMs in the breakthrough and elimination of bacterial biofilms, as well as their application in the field of anti-infection. Finally, the challenges and future development directions of antibacterial MNMs are introduced.