Comparative In Vitro Cytotoxicity Study of Carbon Dot-Based Organometallic Nanoconjugates: Exploration of Their Cell Proliferation, Uptake, and Localization in Cancerous and Normal Cells

Toxicological Effects of Metal-Doped Carbon Quantum Dots

Multi-domain biological and environmental research highlights the efficacy of carbon quantum dots (CQDs) as a safer alternative to toxic metal-based quantum dots (QDs) and expensive conventional organic dyes, particularly in biomedical applications. CQDs are often functionalized by metal heteroatoms to improve their electron-donating properties and modify charge density, thereby enhancing their physicochemical characteristics. However, metal doping may re-introduce toxicity concerns similar to traditional QDs and further increase environmental risks. Thus, detailed ecotoxicology studies are necessary to understand the environmental impact of these CQDs in different organisms. To address this, we synthesized metal-doped CQDs (Mn, Fe, Cu and Ag) using microwave-assisted technique and conducted in-vitro experiments on diverse biological models belonging to different trophic levels, including bacteria (E. coli and B. subtilis), plants (Vigna radiata) and mammalian cells (mouse myoblast cells- C2C12). Results revealed that among all the CQDs explored, Ag-CQDs exhibited highest toxicity causing ~85% bacterial and 100% mammalian cell death even at 10 μg mL-1 and ~60% radicle growth inhibition after 5 days of exposure at 50 μg mL-1, whereas Mn-CQD showed the least toxicity. These findings contribute significantly to the critical need for determining optimal concentration ranges for metal-doped CQDs and enhance our understanding of their environmental implications.

Blazing Carbon Dots: Unfolding its Luminescence Mechanism to Photoinduced Biomedical Applications

Carbon dots (CDs) are carbon-based nanomaterials that have garnered immense attention owing to their exceptional photophysical and optoelectronic properties. They have been employed extensively for biomedical imaging and phototherapy due to their superb water dispersibility, low toxicity, outstanding biocompatibility, and exceptional tissue permeability. This review summarizes the structural classification of CDs, the classification of CDs according to precursor sources, and the luminescence mechanism of CDs. The modification in CDs via various doping routes is comprehensively reviewed, and the effect of such alterations on their photophysical properties, such as absorbance, photoluminescence (PL), and reactive oxygen species generation ability, is also highlighted. This review strives to summarize the role of CDs in cellular imaging and fluorescence lifetime imaging for cellular metabolism. Subsequently, recent advancements and the future potential of CDs as nanotheranostic agents have been discussed. Herein, we have discussed the role of CDs in photothermal, photodynamic, and synergistic therapy of anticancer, antiviral, and antibacterial applications. The overall summary of the review highlights the prospects of CD-based research in bioimaging and biomedicine.

An insight into recent developments of copper, silver and gold carbon dots: cancer diagnostics and treatment

Cancer is one of the most fatal diseases globally, however, advancement in the field of nanoscience specifically novel nanomaterials with nano-targeting of cancer cell lines has revolutionized cancer diagnosis and therapy and has thus attracted the attention of researchers of related fields. Carbon Dots (CDs)-C-based nanomaterials-have emerged as highly favorable candidates for simultaneous bioimaging and therapy during cancer nano-theranostics due to their exclusive innate FL and theranostic characteristics exhibited in different preclinical results. Recently, different transition metal-doped CDs have enhanced the effectiveness of CDs manifold in biomedical applications with minimum toxicity. The use of group-11 (Cu, Ag and Au) with CDs in this direction have recently gained the attention of researchers because of their encouraging results. This review summarizes the current developments of group-11 (Cu, Ag and Au) CDs for early diagnosis and therapy of cancer including their nanocomposites, nanohybrids and heterostructures etc. All The manuscript highlights imaging applications (FL, photoacoustic, MRI etc.) and therapeutic applications (phototherapy, photodynamic, multimodal etc.) of Cu-, Ag- and Au-doped CDs reported as nanotheranostic agents for cancer treatment. Sources of CDs and metals alogwith applications to give a comparative analysis have been given in the tabulated form at the end of manuscript. Further, future prospects and challenges have also been discussed.

Advancing glioblastoma imaging: Exploring the potential of organic fluorophore-based red emissive carbon dots

Over time, the interest in developing stable photosensitizers (PS) which both absorb and emit light in the red region (650 and 950 nm) has gained noticeable interest. Recently, carbon dots (CDs) have become the material of focus to act as a PS due to their high extinction coefficient, low cytotoxicity, and both high photo and thermal stability. In this work, a Federal and Drug Association (FDA) approved Near Infra-Red (NIR) organic fluorophore used for photo-imaging, indocyanine green (ICG), has been explored as a precursor to develop water-soluble red emissive CDs which possess red emission at 697 nm. Furthermore, our material was found to yield favorable red-imaging capabilities of glioblastoma stem-like cells (GSCs) meanwhile boasting low toxicity. Additionally with post modifications, our CDs have been found to have selectivity towards tumors over healthy tissue as well as crossing the blood-brain barrier (BBB) in zebrafish models.

Highin vitroactivity of gold and silver nanoparticles from Solanum mammosum L. against SARS-CoV-2 surrogate Phi6 and viral model PhiX174

The search for new strategies to curb the spread of the SARS-CoV-2 coronavirus, which causes COVID-19, has become a global priority. Various nanomaterials have been proposed as ideal candidates to inactivate the virus; however, because of the high level of biosecurity required for their use, alternative models should be determined. This study aimed to compare the effects of two types of nanomaterials gold (AuNPs) and silver nanoparticles (AgNPs), recognized for their antiviral activity and affinity with the coronavirus spike protein using PhiX174 and enveloped Phi6 bacteriophages as models. To reduce the toxicity of nanoparticles, a species known for its intermediate antiviral activity,Solanum mammosumL. (Sm), was used. NPs prepared with sodium borohydride (NaBH₄) functioned as the control. Antiviral activity against PhiX174 and Phi6 was analyzed using its seed, fruit, leaves, and essential oil; the leaves were the most effective on Phi6. Using the aqueous extract of the leaves, AuNPs-Sm of 5.34 ± 2.25 nm and AgNPs-Sm of 15.92 ± 8.03 nm, measured by transmission electron microscopy, were obtained. When comparing NPs with precursors, both gold(III) acetate and silver nitrate were more toxic than their respective NPs (99.99% at 1 mg ml^-1). The AuNPs-Sm were less toxic, reaching 99.30% viral inactivation at 1 mg ml^-1, unlike the AgNPs-Sm, which reached 99.94% at 0.01 mg ml^-1. In addition, cell toxicity was tested in human adenocarcinoma alveolar basal epithelial cells (A549) and human foreskin fibroblasts. Gallic acid was the main component identified in the leaf extract using high performance liquid chromatography with diode array detection (HPLC-DAD). The FT-IR spectra showed the presence of a large proportion of polyphenolic compounds, and the antioxidant analysis confirmed the antiradical activity. The control NPs showed less antiviral activity than the AuNPs-Sm and AgNPs-Sm, which was statistically significant; this demonstrates that both theS. mammosumextract and its corresponding NPs have a greater antiviral effect on the surrogate Phi bacteriophage, which is an appropriate model for studying SARS-CoV-2.