Fluorescence and UV-vis spectrophotometry: a dual-mode competitive approach for selective sensing of dopamine

Abstract

The quantification of dopamine (DA) is essential due its vital role as neurotransmitter. Here we used the sensing strategy which is based on competition in between DA- resorcinol (RA) reaction and resorcinol stabilized silver nanoparticles (AgNPs) formation in slightly alkaline medium. The AgNPs and DA-RA reaction product formation were well characterized specifically by transmission electron microscopy (TEM) and mass spectrometry, respectively and also by other well known techeniques. The beauty of this sensing strategy is to quantify dopmine using both UV-visible and fluorescence spectrophotometry involving simple chemistry where RA molecule itself acts as a reducing agent and stabilizing agent for the formation of AgNPs and also reacts with DA selectively to produce fluorescent entities in alkaline condition. A dual approach with naked eye recognition of dopamine in ambient light source was developed using the well known chemistry between DA-RA and RA-AgNPs. The interfernce study was performed using both methods and there is almost no interference observed in fluorescence method. The strategy exhibits a high selectivity and sensitivity to DA with a wide linear range of 0.25 μM-30 µM with LOQ, 0.25 µM. Also the assay was performed using human urine sample. The initial assessment of dopamine by fast colorimetric method followed by fluorescence technique enable the strategy to draw a great attention in recent situation.