Inability of antibiotics repertoire to effectively control the progress of multi‐drug resistant (MDR) bacteria has prompted the substantial curiosity among the scientists to seek new tactics to combat the bacterial growth. Therefore, to eradicate the pathogenic bacteria with least cytotoxicity, we employed carbon dots as a broad spectrum of antibacterial weapons in the presence of visible light. Instead of using citric acid, we engaged the penicillin G as a carbon source for the synthesis of penicillin carbon dots (PCDs), which made the carbon dots more aggressive towards pathogenic microbes. Penicillin was also covalently attached to –NH2 containing citric acid based CDs (CDs‐Penicillin) via an amide bond to evaluate whether penicillin in the form of PCD has retained its activity or in its conjugated form (CDs‐Penicillin). Synthesized dots were assessed for their antibacterial activity against Staphylococcus aureus, Escherichia coli (DH5α), MDR Escherichia coli and Methicillin‐resistant Staphylococcus aureus in the presence as well as the absence of visible light. The mechanism of bacteria‐killing through cell wall rupturing was investigated using scanning electron microscopy. Antibacterial assay demonstrates that penicillin in the form of PCDs retained its activity and possess great prospects in the development of new bactericidal therapies to invade the MDR bacteria. Cytotoxicity of both PCDs and CDs‐Penicillin has been evaluated by measuring the viability of human HeLa cells. Fluorescence images of bacteria collected using different excitation wavelength.

The fluorescence resonance energy transfer (FRET) mechanism has been established between carbon dots (CDs) and naphthalimide to monitor the activity of thioredoxin reductase (TrxR), which is often overexpressed in many cancer cells. The naphthalimide moiety was covalently attached to the surface of CDs through a disulfide linkage. In normal cell conditions (when devoid of high concentrations of TrxR), the CDs act as an energy donor and naphthalimide acts as an acceptor, which establishes the FRET pair as interpreted from the emission at λ = 565 nm, when excited at λ = 360 nm. However, contrary to this, the elevated levels of TrxR cause the breakage of disulfide bonds and consequently abolishes the FRET pair through the release of the naphthalimide moiety from the surface of CDs. This process was studied by monitoring of fluorescence intensity at λ = 565 and 440 nm, when excited at the same wavelength (λ = 360 nm). The TrxR based ratiometric quenching and enhancement of fluorescence intensity offers an interesting opportunity to monitor the enzyme activities and has many advantages over conventional monitoring of fluorescence intensity at a single wavelength to avoid interference of external factors. Fluorescence images of cancer cells in response to the nanosensor were visualized under a confocal microscope. Cytotoxicity study of nanosensor retards the growth of HeLa and MCF-7 cell lines in the presence of visible light. Therefore, the nanosensor also acts as a theranostic agent to diagnose as well as killing of cancer cells.

Breast cancer (BC) is the second most common cause of cancer-related deaths in women throughout the world. Multiple drugs have been approved by US-FDA for breast related malignancies. Frequent emergence of resistances creates the severe need of newer moieties that are free from such problems. Drugs targeting breast cancer have been observed to be based on the multiple mechanisms of action, and various indole based anticancer agents have also been explored. Moreover, indoles have promising anti-cancer potential; there has been the emphasis on the synthesis of indole derivatives to overcome problems faced by existing therapeutic agents. Taking into consideration the above-mentioned facts we have analyzed in detail the possible role of indole based anticancer agents typically for breast related malignancies. This is the first exhaustive review that jointly covers various synthetic anticancer indole derivatives and related signaling pathways by which these derivatives have shown promising anti-breast cancer potential.

No abstract

No abstract