Reversible Regulation of the Reactive Oxygen Species Level Using a Semiconductor Heterojunction

Advancements in research on the precise eradication of cancer cells through nanophotocatalytic technology

The rapid development of nanotechnology has significantly advanced the application of nanophotocatalysis in the medical field, particularly for cancer therapy. Traditional cancer treatments, such as chemotherapy and radiotherapy, often cause severe side effects, including damage to healthy tissues and the development of drug resistance. In contrast, nanophotocatalytic therapy offers a promising approach by utilizing nanomaterials that generate reactive oxygen species (ROS) under light activation, allowing for precise tumor targeting and minimizing collateral damage to surrounding tissues. This review systematically explores the latest advancements in highly efficient nanophotocatalysts for cancer treatment, focusing on their toxicological profiles, underlying mechanisms for cancer cell eradication, and potential for clinical application. Recent research shows that nanophotocatalysts, such as TiO2, In2O3, and g-C3N4 composites, along with photocatalysts with high conduction band or high valence band positions, generate ROS under light irradiation, which induces oxidative stress and leads to cancer cell apoptosis or necrosis. These ROS cause cellular damage by interacting with key biological molecules such as DNA, proteins, and lipids, triggering a cascade of biochemical reactions that ultimately result in cancer cell death. Furthermore, strategies such as S-scheme heterojunctions and oxygen vacancies (OVs) have been incorporated to enhance charge separation efficiency and light absorption, resulting in increased ROS generation, which improves photocatalytic performance for cancer cell targeting. Notably, these photocatalysts exhibit low toxicity to healthy cells, making them a safe and effective treatment modality. The review also discusses the challenges associated with photocatalytic cancer therapy, including limitations in light penetration and the need for improved biocompatibility. The findings suggest that nanophotocatalytic technology holds significant potential for precision cancer therapy, paving the way for safer and more effective treatment strategies.

Gold nanoclusters stabilized with dopa-containing ligands: Catalyst-indicator integrated probe for tumor cell screening

Elevated hydrogen peroxide (H2O2) levels not only inflict cellular damage but also serve as a harbinger for various diseases. Tumor cells, in particular, often exhibit an abundance of H2O2. Hence, the detection of this pivotal molecule assumes paramount importance in monitoring physiological states and expediting cancer diagnosis. To this end, we have ingeniously devised an enzyme-free and monomeric system for intracellular H2O2 detection. Our astute selection of dopa-containing peptidomimetics, replete with ortho-bisphenol and amino acid moieties, has engendered the synthesis of distinctive fluorescent gold nanoclusters (AuNCs). These nanoclusters not only function as a peroxidase-like catalyst, catalyzing the decomposition of H2O2 into hydroxyl radicals (·OH), but also serve as an indicator, with their fluorescence quenched in response to varying H2O2 concentrations. Experimental results evince that our GDpE-AuNCs exhibit remarkable sensitivity, boasting a detection limit of 0.49 μM and a linear range of 5-1000 μM. Moreover, the amalgamation of catalyst and indicator within a single structure, facilitating efficient cellular uptake, engenders intracellular H2O2 detection and discernment of tumor cells. This pioneering approach bequeaths a valuable assay probe for monitoring physiological states and ushering in early disease diagnosis.

Lysis-Free Isolation and Direct Amplification of Pathogenic Bacterial DNA Using Diatom Frustules

DNA has been implicated as an important biomarker for the diagnosis of bacterial infections. Herein, we developed a streamlined methodology that uses diatom frustules (DFs) to liberate and capture bacterial DNA and allows direct downstream amplification tests without any lysis, washing, or elution steps. Unlike most conventional DNA isolation methods that rely on cell lysis to release bacterial DNA, DFs can trigger the oxidative stress response of bacterial cells to promote bacterial membrane vesicle formation and DNA release by generating reactive oxygen species in aqueous solutions. Due to the hierarchical porous structure, DFs provided high DNA capture efficiency exceeding 80% over a wide range of DNA amounts from 10 pg to 10 ng, making only 10 μg DFs sufficient for each test. Since laborious liquid handling steps are not required, the entire DNA sample preparation process using DFs can be completed within 3 min. The diagnostic use of this DF-based methodology was illustrated, which showed that the DNA of the pathogenic bacteria in serum samples was isolated by DFs and directly detected using polymerase chain reaction (PCR) at concentrations as low as 102 CFU/mL, outperforming the most used approaches based on solid-phase DNA extraction. Furthermore, most of the bacterial cells were still alive after DNA isolation using DFs, providing the possibility of recycling samples for storage and further diagnosis. The proposed DF-based methodology is anticipated to simplify bacterial infection diagnosis and be broadly applied to various medical diagnoses and biological research.

Zinc-mineralized diatom biosilica/hydroxybutyl chitosan composite hydrogel for diabetic chronic wound healing

For sustained and stable improvement of the diabetic wound microenvironment, a temperature-sensitive composite hydrogel (ZnDBs/HBC) composed of inorganic zinc mineralized diatom biosilica (ZnDBs) and hydroxybutyl chitosan (HBC) was developed. The interfacial anchoring effect between ZnDBs and HBC enhanced the mechanical strength of the hydrogel. The mechanical strength of the composite hydrogel containing 3 wt% ZnDBs was increased by nearly 2.3times. The hydrogel can be used as a carrier for sustained release of Zn2+ for at least 72 h. In diabetic rats models, ZnDBs/HBC composite hydrogel could accelerate the inflammatory process by regulating the expression of pro-inflammatory factor IL-6 and anti-inflammatory factor IL-10, and also promote tissue cell proliferation and collagen deposition, thereby restoring the normal healing process and accelerating wound healing. The wound contraction rate of the composite hydrogel group was more than 2 times that of the control group. Therefore, ZnDBs/HBC composite hydrogel has the potential to be used as a therapeutic dressing for diabetic chronic wounds.

The Art of Exploring Diatom Biosilica Biomaterials: From Biofabrication Perspective

Diatom is a common single-cell microalgae with large species and huge biomass. Diatom biosilica (DB), the shell of diatom, is a natural inorganic material with a micro-nanoporous structure. Its unique hierarchical porous structure gives it great application potential in drug delivery, hemostat materials, and biosensors, etc. However, the structural diversity of DB determines its different biological functions. Screening hundreds of thousands of diatom species for structural features of DB that meet application requirements is like looking for a needle in a seaway. And the chemical modification methods lack effective means to control the micro-nanoporous structure of DB. The formation of DB is a typical biomineralization process, and its structural characteristics are affected by external environmental conditions, genes, and other factors. This allows to manipulate the micro-nanostructure of DB through biological regulation method, thereby transforming the screening mode of the structure function of DB from a needle in a seaway to biofabrication mode. This review focuses on the formation, biological modification, functional activity of DB structure, and its application in biomaterials field, providing regulatory strategies and research idea of DB from the perspective of biofabrication. It will also maximize the possibility of using DB as biological materials.