Tuning the photophysical properties of cyanine by barbiturate functionalization and nanoformulation for efficient optoacoustics- guided phototherapy.

Cyanine derivatives are organic dyes widely used for optical imaging. However, their potential in longitudinal optoacoustic imaging and photothermal therapy remains limited due to challenges such as poor chemical stability, poor photostability, and low photothermal conversion. In this study, we present a new structural modification for cyanine dyes by introducing a strongly electron-withdrawing group (barbiturate), resulting in a new series of barbiturate-cyanine dyes (BC810, BC885, and BC1010) with suppressed fluorescence and enhanced stability. Furthermore, the introduction of BC1010 into block copolymers (PEG114-b-PCL60) induces aggregation-caused quenching, further boosting the photothermal performance. The photophysical properties of nanoparticles (BC1010-NPs) include their remarkably broad absorption range from 900 to 1200 nm for optoacoustic imaging, allowing imaging applications in NIR-I and NIR-II windows. The combined effect of these strategies, including improved photostability, enhanced nonradiative relaxation, and aggregation-caused quenching, enables the detection of optoacoustic signals with high sensitivity and effective photothermal treatment of in vivo tumor models when BC1010-NPs are administered before irradiation with a 1064 nm laser. This research introduces a barbiturate-functionalized cyanine derivative with optimal properties for efficient optoacoustics-guided theranostic applications. This new compound holds significant potential for biomedical use, facilitating advancements in optoacoustic-guided diagnostic and therapeutic approaches.

Synthesis and characterization of organoselenium based BODIPY and its application in living cells.

Phenylselenide based BODIPY probe was successfully synthesized and characterized by NMR spectroscopic techniques (1H, 13C and 77Se NMR), mass spectrometry and single crystal XRD. Surprisingly, crystal packing diagram of the probe showed formation of 1-D strip through intermolecular F---H interaction. The probe was screened with various Reactive Oxygen Species (ROS) and found to be selective for superoxide ion over other ROS via "turn-on" fluorescence response. The probe selectively and sensitively detects superoxide with a lower detection limit (43.34 nM) without interfering with other ROS. The quantum yield of the probe was found to increase from 0.091 % to 30.4 % (334-fold) after oxidation. Theoretical calculations (DFT and TD-DFT) were also performed to understand the sensing mechanism of the probe. The probe was able to effectively detect superoxide inside living cells without any toxic effect.

Synthesis and Photophysical Study of Tetraphenyl Substituted BODIPY Based Phenyl-Monoselenide Probe for Selective Detection of Superoxide.

Selenium containing tetraphenyl substituted BODIPY probe was successfully synthesized from respective selenium aldehyde and tetraphenyl pyrrole using Knoevenagel-type condensation. The product was characterized using various spectroscopic techniques (1 H, 13 C, 77Se, 11B, and 19 F) and mass spectrometry. The probe was found to be selective and sensitive towards detection of superoxide over other ROS with a "turn-off" (quenched) fluorescence response. The detection limit of the probe was found to be 4.87 µM. The probe reacted with superoxide in less than a sec with a stoke shift of 35 nm.

Synthesis and single crystal X-ray study of phenylselenyl embedded coumarin-based sensors for selective detection of superoxide.

Selenium-coumarin based probe 4 was synthesized from the reaction of a bromo derivative of coumarin with in situ prepared sodium phenyl selenide. Esterification of probe 4 resulted in the formation of probe 5. In the single crystal X-ray structure of probe 4, the phenylselenide group was placed parallel to the coumarin moiety whereas in probe 5, the phenylselenide group was perpendicular to the coumarin group. Hydrogen bonding interactions have been observed in the crystal packing of both the probes. Both the probes selectively detect superoxide over other reactive oxygen species (ROS). A kinetic study of the probes was performed, which suggested that probe 4 achieved maximum fluorescence intensity in less than 1 s while probe 5 required 30 min to attain maximum fluorescence intensity. Both probes 4 and 5 showed 37 fold and 48 fold increase in fluorescence intensity after the reaction with superoxide, respectively. The detection limits of probes 4 and 5 were found to be 46.4 nM and 48.9 nM, respectively. Both the probes showed reversibility with biothiols such as glutathione (GSH) and N-acetyl-L-cysteine (NAC). Probe 5 underwent more redox cycles with GSH compared to probe 4.

A BOPHY based fluorescent probe for Hg2+via NTe2 chelation.

A BOPHY-based organotellurium-containing probe was synthesized and characterized via single crystal XRD for the selective and sensitive detection of Hg2+ over other metal ions. The probe detects Hg2+ in less than 1 s with a 2.5-fold enhancement in fluorescent intensity. Due to the chalcogenophilicity of mercury, Hg2+ was facilely trapped in the NTe2 chelating cavity of the probe. The probe can detect Hg2+ in the nanomolar range (62 nM) and it showed reversibility with S2- ions. The sensitivity of the probe for the detection of Hg2+ was confirmed in living HeLa cells.