Kondapa Naidu Bobba

Resorufin based fluorescence ‘turn-on’ chemodosimeter probe for nitroxyl (HNO)

A cellular responsive, highly selective fluorogenic and chromogenic chemodosimeter probe for HNO is developed. This new probe showed ∼30 fold fluorescence enhancement in the presence of HNO and is sensitive to HNO at concentrations as low as 0.02 μM. Further, it is capable of detecting HNO levels in cellular milieus as well as in live specimens e.g. C. elegans.

GSH-responsive biotinylated poly(vinyl alcohol)-grafted GO as a nanocarrier for targeted delivery of camptothecin

A water-soluble and biocompatible polymer, i.e. biotinylated poly(vinyl alcohol)-grafted graphene oxide (GO), was used as a nanocarrier for targeted delivery of anticancer drug camptothecin (CPT). The extent of CPT release in the presence of glutathione (GSH) from GO–biotinPVA–CPT was monitored by the increase in the fluorescence intensity, at λmax = 450 nm. The cell-specific (HeLa) antiproliferative activity of GO–biotinPVA–CPT makes it suitable to be used for targeted delivery of chemotherapeutics to cancerous cells.

A hydrogen sulfide triggered self-immolative fluorescent probe for lysosome labeling in live cells

We developed a naphthalimide-based, lysosome-targeting, and self-immolative fluorescent probe for H2S detection. Probe LS-1 comprises a 2-formylbenzoate derivative of the 1,8-naphthalimide fluorophore. H2S forms a thiohemiacetal intermediate by reacting with the formyl group of the 2-formylbenzoate derivative, which subsequently undergoes intramolecular cyclization with the ester moiety to generate a free naphthalimide fluorophore (FL-1). The UV-vis absorbance (λabs) value of probe LS-1 at 450 nm increased in the presence of H2S. Similarly, with increasing H2S concentrations, the emission band (λem) centered at 560 nm increased gradually. The probe was found to be highly sensitive and chemoselective towards H2S compared with other biological analytes. Probe LS-1 was nontoxic and very stable across the physiological pH range. The probe LS-1 enables the detection of intracellular endogenous H2S formation in HT29 cells in lysosomes.

Azo-based small molecular hypoxia responsive theranostic for tumor-specific imaging and therapy

ABSTRACT We report herein, an azo‐derivative (AzP1) of FDA approved antineoplastic drug SN‐38 (irinotecan analogue) as a theranostic agent with a potential for both tumor hypoxia‐specific activation and therapy. The theranostic AzP1 was found to be stable within a biologically relevant pH scale and was chemically inert towards other competitive biological analytes. However, upon treatment with rat‐liver microsomes, AzP1 showed a self‐calibrated fluorescence enhancement at &lgr;em = 560 nm. The cytotoxicity profile of AzP1 was tested in various cancer lines. Under hypoxic conditions, prodrug AzP1 exhibited activation to release the parent drug (SN‐38) and enhanced cytotoxicity in cancer cells with concomitant fluorescence enhancement at 560 nm, which served to monitor both the drug activation and tracing purposes. The therapeutic potential of AzP1 for both tumor‐specific activation and suppression of tumor weights was validated in xenograft mouse model. Collectively, the synthetic ease and hypoxia‐sensitive activation along with promising therapeutic properties highlight the potential of theranostic AzPI in future cancer treatment programs. Graphical abstract Figure. No Caption available.