SYNTHESIS AND CHARACTERIZATION OF FLUORESCENCE PROBES: METAL ION DETECTION AND PROTEIN INTERACTION STUDIES

Abstract

Fluorescence probe I I 2-ineIhoxy-4-(naphihalene- / -yln)iino)nie1hyl,phenolJ. 2 [2-nwihoxy--/- (((-l-ine1/wx),phenvl)iminonze/hyl)phenoIj and 3 [2- (1-(naphi hale- I -),/imino)e!hyl,)pheno/j have been synthesized and fulty characterized by various spactroscopic methods namely IR, tV-vis. NMR (Il1 and ' DC) and ESI-MS spectral studies. Fluorescence probe 4 [Bismark Brovn R (l313R)] is commercially available in the market. We investigated metal ion detection by these fluorescence probes in the presence of various metal ions {Ca(ll). Mu(ll). Cr(lll). Mn(ll). Fe(ll). Fe(111). Co(ll), Ni(ll). Cu(ll), Zn(ll) and l-lg(ll)j in methanol by fluorescence specroscopy. For probe 1 enhancement of fluorescence spectral intensity was observed in presence of Fe(IIl) ion only and this probe clearly detected Fe(lll) ion in methanolic solution. A slight enhancement of fluorescence was observed in case of' probe 2 for Mn' ion in methanolic solution. Interestingly, for probe 3 enhancement of fluorescence spectral intensity was observed in presence of Fe(lIl) ion only. On the other hand a new band at 435 nm was observed in the fluorescence spectra clearly showing turn-on fluorescence. We did not observe any effect of metal ion in case ofprobe 4. l'he protein interaction of these Iluorescence probes 1. 2. 3 and 4 with bovein serum albumin (BSA) were investigated in Na-phosphate buffer (p11 7.2). We observed that all these fluorescence probes were act as a qLlenCher for BSA at excitation wavelength 295 nm and emission wavcicnflh at 345 nm. Stern-Volmer quenching constants were determined using fluorescence spectral stLlclies. The maximum Stern-Volmer quenching constant was observed for the fluorescence probe I while minimum for the fluorescence probe 4 (BBR). These results indicate that extent of'binding with BSA is most significant for fluorescence probe 1.