Sceptrin-Au nano-aggregates (SANA) for overcoming drug-resistant Gram-negative bacteria

Photothermal Antibacterial Therapy of Near-Infrared II Region Laser Mediated by Gold Hollow Nanorod

The current traditional treatment for bacterial infections is to treat them with antibiotics, and the misuse of antibiotics can lead to an increase in bacterial resistance. In contrast, the development of new antibiotics is much slower than the speed of adaptation of drug-resistant bacteria, making it necessary to develop a drug that does not rely on antibiotics. Therefore, based on the advantages of photothermal therapy, NIR II-responsive gold hollow nanorods (GHNRs) were developed to overcome the limitation of bacterial drug resistance in conventional bacterial therapy. GHNRs can quickly respond to a 980 nm laser with a high photothermal conversion efficiency of 41.78%. The high temperature produced by GHNRs can effectively kill Staphylococcus aureus and Escherichia coli, providing a new strategy for the clinical treatment of bacterial infectious diseases without antibiotic dependence.

Postsynthetic Modification of Thermo-Treated Metal-Organic Framework for Combined Photothermal/Photodynamic Antibacterial Therapy

Metal-organic frameworks (MOFs) are emerging porous materials that can serve as carriers of photosensitizers and photothermal agents. Meanwhile, a large number of active sites in MOFs endow them with the characteristics of modification by postsynthetic modification. Herein, a dual-modal PDT/PTT therapeutic agent HMIL-121-acriflavine-tetrakis (4-amoniophenyl) porphyrin (HMIL-ACF-Por), prepared by the postsynthetic modification of the MOF (HMIL-121), was reported for antibacterial applications. The prepared HMIL-ACF-Por enables the generation of abundant reactive oxygen species, including the superoxide anion radical (O2-) and singlet oxygen (1O2), and thermal energy under 808 nm NIR laser irradiation. HMIL-ACF-Por showed good antibacterial ability against Escherichia coli and Staphylococcus aureus in vitro. Meanwhile, HMIL-ACF-Por can effectively inhibit the inflammatory response caused by bacterial infection and accelerate S. aureus-infected wound healing under laser irradiation owing to the synergistic effect of photodynamic therapy (PDT) and photothermal therapy (PTT). These results demonstrate that HMIL-ACF-Por is a promising PDT/PTT therapeutic agent. This work also contributes to offering an effective solution for treating bacterial infections and promotes the application of MOF-based materials in biomedicine.

In Situ Activatable Nitrobenzene-Cysteine-Copper(II) Nano-complexes for Programmed Photodynamic Cancer Therapy

Photodynamic therapy (PDT) has been used to reduce cancerous and precancerous cells via reactive oxygen species (ROS) generation from photosensitizers. Numerous photosensitizers are available today to treat a variety of diseases, but their therapeutic efficacy is hindered within the tumor microenvironment, and there are safety concerns associated with their non-specific activation. In this work, we disclosed a nano-therapeutic based on in situ activatable nitrobenzene-cysteine-copper(II) nano-complexes (NCCNs) that work within cancer cells. Among the NCCNs, CyP shows outstanding potential as a promising candidate for programmed photodynamic cancer therapy with its unique properties such as (i) bright near-infrared imaging, (ii) chemodynamic therapeutic effect, (iii) photodynamic therapeutic effect (types I and II), and (iv) anti-cancer effect by anti-angiogenesis in early cancer stage under light. Overall, this work opens up exciting possibilities for the development of innovative and effective treatments for cancer, paving the way for future advancements in the clinical medicine field.

Quaternized carbon dots with enhanced antimicrobial ability towards Gram-negative bacteria for the treatment of acute peritonitis caused by E. coli

Infections caused by Gram-negative bacteria still pose a clinical challenge. Although nanomaterials have been developed for antibacterial treatments, a systematic evaluation of the mechanisms and intervention models of antibacterial materials toward Gram-negative bacteria is still lacking. Herein, antibacterial quaternized carbon dots (QCDs) were synthesized via a one-step melting method using anhydrous citric acid and diallyl dimethyl ammonium chloride (DDA). The QCDs exhibited effective broad-spectrum antibacterial activity and enhanced inhibitory ability towards Gram-negative bacteria. The antibacterial mechanism of the QCDs with respect to Gram-negative bacteria was investigated through the characterization of bacterial morphology changes, the absorption modes of the QCDs on bacteria, and the potential generation of reactive oxygen species by the QCDs. The QCDs showed low toxicity in different cells, and did not cause hemolysis. The QCDs were administered via intraperitoneal injection to treat acute peritonitis in mice infected with E. coli. Routine blood examination, magnetic resonance imaging, and pathological analysis were undertaken and it was found that, similar to the positive control group treated with gentamicin sulfate, the QCDs exhibited a therapeutic effect that eliminated infection and inflammation. This study explores a controllable synthetic strategy for the synthesis of active carbon dots with antibacterial activity, a material that is a promising candidate for new treatments of Gram-negative bacterial infections.

Dimeric pyrrole-imidazole alkaloids: sources, structures, bioactivities and biosynthesis

Pyrrole-imidazole alkaloids (PIAs) constitute a highly diverse and densely functionalized subclass of marine natural products. Among them, the uncommon dimeric PIAs with ornate molecular architectures, attractive biological properties and interesting biosynthetic origin have spurred a considerable interest of chemists and biologists. The present review comprehensively summarized 84 dimeric PIAs discovered during the period from 1981 to September 2022, covering their source organisms, chemical structures, biological activities as well as biosynthesis. For a better understanding, these structurally intricate PIA dimers are firstly classified and presented according to their carbon skeleton features as well as biosynthesis pathways. Furthermore, relevant summaries focusing on the source organisms and the associated bioactivities of these compounds belonging to different chemical classes are also provided, which will help elucidate the fascinating chemistry and biology of these unusual PIA dimers.