Tuning the Luminescence of Microwave-Assisted N-Doped Fluorescent Carbon Dots: Bioimaging Applications and Label-Free Anti-Cancer Drug Delivery.

Nanosized fluorescent carbon dots (Cdots) have gained a lot of attention in the recent years because of their superior properties, such as good biocompatibility, low toxicity, excellent chemical stability, resistance to photobleaching, and ease of chemical modification. Cdots are promising candidates for considerable applications in various fields: sensors, bioimaging, and drug delivery. Specifically, nitrogen-doped Cdots have attracted a huge interest because of their applicability in bioimaging and drug delivery. Conventional methods for the synthesis of Cdots have drawbacks, such as the use of organic solvents, the presence of side products, and the time required for synthesis. Keeping all these points in mind, herein, we report green methodology for the synthesis of water-soluble, blue-emitting, nitrogen-doped multifunctional Cdots under microwave irradiation within 3 min. The Cdots were prepared using citric acid and arginine as source materials and were characterized using various physicochemical techniques. A pH-responsive drug delivery system was then designed using anticancer drug doxorubicin and the synthesized Cdots. The biocompatibility of synthesized Cdots was analyzed against L929 normal cell line. The Cdots-DOX conjugates exhibited efficient anticancer activity against HeLa cells and also acted as excellent bioimaging agents.

Femtomolar detection of staphylococcal enterotoxin 'B' using a fluorescent quantum dot based hybrid Apta-immunosensor.

Food poisoning is a gastrointestinal illness caused by food-borne enterotoxin produced by the bacterium Staphylococcus aureus. The effective dose of Staphylococcal enterotoxin 'B' (SEB) is estimated to be 0.4 ng/kg of body weight, whereas the 50 % lethal dose is found to be 20 ng/kg of body weight for humans exposed by the inhalation route. The present report highlights the development of a fluorescence resonance energy transfer (FRET) based assay for the detection of Staphylococcal enterotoxin. Highly fluorescent, aqueous quantum dots were synthesized and conjugated with Staphylococcal enterotoxin 'B' specific bioreceptors. SEB specific aptamer and SEB antibody were labeled with fluorescent quantum dots for recognizing and binding two separate epitopes in the SEB. A combination of two probes against different epitopic regions in a homogeneous sandwich assay format enhanced the sensitivity and specificity of SEB detection. In the presence of the enterotoxin, both the aptamer and antibody came in close proximity with each other and FRET was observed. A linear decrease in the fluorescence at 562 nm and a corresponding increase in the signal at 644 nm was observed with increasing concentrations of SEB, when excited at the absorption maximum of quantum dots. The limit of detection for the developed assay obtained was less than 1 ng/ml. The method was employed in apple juice and quantitated using Enzyme-linked Immunosorbent Assay (ELISA). The designed assay was rapid and robust and can be extrapolated as a platform for the detection of various disease-causing agents of biomedical significance.

Recent Development in Indole Derivatives as Anticancer Agent: A Mechanistic Approach.

BACKGROUND: Cancer accounts for several deaths each year. There are multiple FDA approved drugs for cancer treatments. Due to the severe side effects and multiple drug resistance, the current drug therapies become ineffective. So, the newer moieties with fewer toxic effects are necessary for the development. OBJECTIVE: The mechanism of indole derivatives as anti-cancer agents with their major target is explored in detail in this article. METHODS: Recent advances and mechanism of indole derivatives as anti-cancer agents are reviewed. This review suggests a detailed explanation of multiple mechanisms of action of various indole derivatives: cell cycle arrest, aromatase inhibitor estrogen receptor regulator, tubulin inhibitor, a tyrosine kinase inhibitor, topoisomerase inhibitors, and NFkB/PI3/Akt/mTOR pathway inhibitors, through which these derivatives have shown promising anti-cancer potential. RESULTS: A full literature review showed that the indole derivatives are associated with the properties of inducing apoptosis, aromatase inhibition, regulation of estrogen receptor and inhibition of tyrosine kinase, tubulin assembly, NFkB/PI3/Akt/mTOR pathway, and HDACs. These derivatives have shown significant activity against cancer cell lines. CONCLUSION: Indole derivatives seem to be important in cancer via acting through various mechanisms. This review has shown that the indole derivatives can further be explored for the betterment of cancer treatment, and to discover the hidden potential of indole derivatives.