Browsing by Author "Bobba, Kondapa Naidu"

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A hydrogen sulfide triggered self-immolative fluorescent probe for lysosome labeling in live cells
(2018-02-07)
Velusamy, Nithya
;
Thirumalaivasan, Natesan
;
Bobba, Kondapa Naidu
;
Wu, Shu-Pao
;
Bhuniya, Sankarprasad
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 (lambda(abs)) value of probe LS-1 at 450 nm increased in the presence of H2S. Similarly, with increasing H2S concentrations, the emission band (lambda(em)) 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.
FRET-based dual channel fluorescent probe for detecting endogenous/exogenous H2O2/H2S formation through multicolor images
(2019-02-01)
Velusamy, Nithya
;
Thirumalaivasan, Natesan
;
Bobba, Kondapa Naidu
;
Podder, Arup
;
Wu, Shu-Pao
We have developed a FRET-based fluorescent probe (PHS1) as a combination of two different fluorophores (coumarin and naphthalimide); which can detect both exogenous and endogenous H2S and H2O2 in live cells through multicolor images. The precise overlap between UV-absorption of naphthalimide and the emission band of coumarin in probe PHS1 allows the acquisition of the self-calibrated information of dual analytes through FRET-based imaging. The UV-Vis absorption (lambda(abs) 390 nm) and fluorescence emission (lambda(em) 460 nm) of probe PHS1 in the presence of H2O2 are increased similar to 35-fold and similar to 15-fold respectively. It also allows the estimation of the levels of H2S through enhancement of emission intensity at 550 nm. The probe PHS1 exhibits high stability against various analytes, including various pH (4-9.5). The cell viability assay data indicate that the probe is not harmful to the cancer cells. The nontoxic nature of the probe PHS1 encourages application for cancer cell labeling. The probe PHS1 can detect the level of endogenous H2O2, H2S, and H2O2/H2S in cancer cells through blue, green and FRET-based green channel imaging. PHS1 is a unique probe, has potential application for diagnosing cancer by providing information on the level of dual analytes (H2S, H2O2) in cancer cells.