Decorating Vitamin B6 Cofactor over Beta-Cyclodextrin Stabilized Silver Nanoparticles through Inclusion Complexation for Fluorescent Turn-On Detection of Hydrazine.

Contamination of hydrazine has severe effects on the environment and security systems due to its potent toxic and explosive nature. Therefore, the concept of nano and supramolecular chemistry was applied to develop a nanoassembly for the fluorescent turn-on detection of hydrazine. Weakly emissive silver nanoparticles (AgNPs) decorated with beta-cyclodextrin (ß-CD) of size ∼7 nm (ß-CD-AgNPs) was synthesized, characterized, and interacted with pyridoxal 5'-phosphate (PLP). With the addition of vitamin B6 cofactor PLP into the ß-CD-AgNPs solution resulted an instantaneous fluorescence enhancement at 532 nm due to the inclusion complexation occurred between the PLP and the ß-CD decorated over AgNPs. The formation of inclusion complex between PLP and ß-CD was investigated additionally by various theoretical and experimental methods. The nanoassembly PLP_ß-CD-AgNPs upon interaction with hydrazine showed a selective turn-on fluorescence at 515 nm. The aldehyde group of PLP acts as the recognition unit and formed a Schiff base upon interaction with hydrazine. This nanoassembly can detect the concentration of hydrazine down to 0.513 µM, and applied successfully to quantify hydrazine from the real environmental samples.

Mimicking biological process to detect alkaline phosphatase activity using the vitamin B6 cofactor conjugated bovine serum albumin capped CdS quantum dots.

This manuscript presents a novel bioanalytical approach for the selective ratiometric fluorescent sensing of enzymatic activity of the alkaline phosphatase (ALP) in the biological samples. The probe was designed by conjugating the pyridoxal 5'-phosphate (PLP) over the surface of bovine serum albumin (BSA) stabilized CdS quantum dots (QDs) through the interaction of free amine present in BSA with the aldehyde group of PLP. The conjugation of PLP quenched the emission of QDs. Upon addition of the ALP, the emission of QDs was restored due to the dephosphorylation and the conversion of the functionalized PLP in to pyridoxal. With this probe, the ALP activity can be detected down to 0.05 U/L and also successfully applied for the detection of ALP activity in biological samples such as human serum and plasma.