Understanding of catalytic ROS generation from defect-rich graphene quantum-dots for therapeutic effects in tumor microenvironment

Metal-Free Carbon Co-Catalysts for Up-Conversion Photo-Induced Catalytic Cancer Therapy

Near-infrared (NIR)-responsive metal-free carbon co-catalysts that convert glucose into H2O2 to generate reactive oxygen species (ROS) are developed from phosphorus-doped carbon nitride (P-C3N4) and graphene quantum dots (GQD) composites, for enhanced photocatalytic cancer therapy by light exposure in the targeted tumor microenvironment. Upon irradiation, the NIR light is converted by GQD with up-conversion function into visible light to excite P-C3N4 for photocatalytic conversion of glucose into H2O2, which subsequently decomposes into ROS. ROS thus generated exhibits an excellent anticancer efficacy for efficient cancer therapy with minimal side effects, as evidenced by both in vitro and in vivo studies. This study demonstrates, for the first time, a cancer therapeutic of GQD/P-C3N4 composite that utilizes a two-step cascade effect using initially NIR-triggered GQD nanoparticles to activate P-C3N4 to photocatalytically generate ROS for effective and targeted cancer therapy.

Exploration of the Graphene Quantum Dots-Blue Light Combination: A Promising Treatment against Bacterial Infection

Graphene Quantum Dots (GQDs) have shown the potential for antimicrobial photodynamic treatment, due to their particular physicochemical properties. Here, we investigated the activity of three differently functionalized GQDs-Blue Luminescent GQDs (L-GQDs), Aminated GQDs (NH2-GQDs), and Carboxylated GQDs (COOH-GQDs)-against E. coli. GQDs were administrated to bacterial suspensions that were treated with blue light. Antibacterial activity was evaluated by measuring colony forming units (CFUs) and metabolic activities, as well as reactive oxygen species stimulation (ROS). GQD cytotoxicity was then assessed on human colorectal adenocarcinoma cells (Caco-2), before setting in an in vitro infection model. Each GQD exhibits antibacterial activity inducing ROS and impairing bacterial metabolism without significantly affecting cell morphology. GQD activity was dependent on time of exposure to blue light. Finally, GQDs were able to reduce E. coli burden in infected Caco-2 cells, acting not only in the extracellular milieu but perturbating the eukaryotic cell membrane, enhancing antibiotic internalization. Our findings demonstrate that GQDs combined with blue light stimulation, due to photodynamic properties, have a promising antibacterial activity against E. coli. Nevertheless, we explored their action mechanism and toxicity on epithelial cells, fixing and standardizing these infection models.

Innovative approaches for cancer treatment: graphene quantum dots for photodynamic and photothermal therapies

Graphene quantum dots (GQDs) hold great promise for photodynamic and photothermal cancer therapies. Their unique properties, such as exceptional photoluminescence, photothermal conversion efficiency, and surface functionalization capabilities, make them attractive candidates for targeted cancer treatment. GQDs have a high photothermal conversion efficiency, meaning they can efficiently convert light energy into heat, leading to localized hyperthermia in tumors. By targeting the tumor site with laser irradiation, GQD-based nanosystems can induce selective cancer cell destruction while sparing healthy tissues. In photodynamic therapy, light-sensitive compounds known as photosensitizers are activated by light of specific wavelengths, generating reactive oxygen species that induce cancer cell death. GQD-based nanosystems can act as excellent photosensitizers due to their ability to absorb light across a broad spectrum; their nanoscale size allows for deeper tissue penetration, enhancing the therapeutic effect. The combination of photothermal and photodynamic therapies using GQDs holds immense potential in cancer treatment. By integrating GQDs into this combination therapy approach, researchers aim to achieve enhanced therapeutic efficacy through synergistic effects. However, biodistribution and biodegradation of GQDs within the body present a significant hurdle to overcome, as ensuring their effective delivery to the tumor site and stability during treatment is crucial for therapeutic efficacy. In addition, achieving precise targeting specificity of GQDs to cancer cells is a challenging task that requires further exploration. Moreover, improving the photothermal conversion efficiency of GQDs, controlling reactive oxygen species generation for photodynamic therapy, and evaluating their long-term biocompatibility are all areas that demand attention. Scalability and cost-effectiveness of GQD synthesis methods, as well as obtaining regulatory approval for clinical applications, are also hurdles that need to be addressed. Further exploration of GQDs in photothermal and photodynamic cancer therapies holds promise for advancements in targeted drug delivery, personalized medicine approaches, and the development of innovative combination therapies. The purpose of this review is to critically examine the current trends and advancements in the application of GQDs in photothermal and photodynamic cancer therapies, highlighting their potential benefits, advantages, and future perspectives as well as addressing the crucial challenges that need to be overcome for their practical application in targeted cancer therapy.

Effect of defects on optical and electronic properties of graphene quantum dots: a density functional theory study

The effects of different types of defects (vacancy, Stone-Wales defects, and heteroatom doping) and varying defect concentrations (single and double defects) on the structure, electronic, and optical properties of graphene quantum dots (GQDs) are systematically investigated using time-dependent density functional theory (TD-DFT). The results reveal that most defects induce noticeable structural distortions, with increasing deformation at higher defect concentrations. Compared to pristine GQD model C96 (with a maximum absorption peak at 592 nm), the absorption spectra of 6 defective C96 exhibit blue shifts ranging from 554 to 591 nm, while 12 defective C96 lead to red shifts (598-668 nm). The HOMO-LUMO gaps vary from 0.62 to 2.04 eV (2.10 eV for pristine C96). Quantitative analysis of the absorption spectra and molecular orbital energy levels demonstrate that the electronic and optical properties of defective C96 strongly depend on the types, concentrations, and locations of defects. NTO analysis illustrates that higher electron localization exists in defective C96, which is attributed to the disruption of the original π-conjugation caused by structural distortions and different orbital hybridizations. These findings offer a comprehensive insight into the impact of defects on GQDs and provide valuable guidance for exploiting the unique features of GQDs to expand new applications in various fields.

Two-dimensional metal-organic frameworks: from synthesis to bioapplications

As a typical class of crystalline porous materials, metal-organic framework possesses unique features including versatile functionality, structural and compositional tunability. After being reduced to two-dimension, ultrathin metal-organic framework layers possess more external excellent properties favoring various technological applications. In this review article, the unique structural properties of the ultrathin metal-organic framework nanosheets benefiting from the planar topography were highlighted, involving light transmittance, and electrical conductivity. Moreover, the design strategy and versatile fabrication methodology were summarized covering discussions on their applicability and accessibility, especially for porphyritic metal-organic framework nanosheet. The current achievements in the bioapplications of two-dimensional metal-organic frameworks were presented comprising biocatalysis, biosensor, and theranostic, with an emphasis on reactive oxygen species-based nanomedicine for oncology treatment. Furthermore, current challenges confronting the utilization of two-dimensional metal-organic frameworks and future opportunities in emerging research frontiers were presented.