Optofluidic laser sensor for the detection of dopamine

Abstract

Dopamine (DA) is a biomarker of many psychiatric diseases, such as schizophrenia and Parkinson's disease. Most current DA detection research adopts electrochemical method, which suffers interferences caused by many analogs with similar structures or redox potentials. To realize highly sensitive and selective DA sensing, herein we propose an optofluidic-laser-based DA sensor. Via the competitive adsorption mechanism, rhodamine 6G (Rh6G) is fixed on graphene oxide (GO) and replaced by DA in the sample, with the re-excited Rh6G serving as the gain medium of the optofluidic laser. As the DA concentration increases, more Rh6G is released into the sample, which induces an increase in the relative slope efficiency of the optofluidic laser and a reduction in the laser threshold. Both the relative slope efficiency and threshold attain a suitable linear relationship with the DA concentration within the 5–800 μM range. Under ideal circumstances, the detection limit of the biosensor is 0.3 µM. Moreover, the optofluidic laser-based biosensor achieves favorable selectivity for DA detection, proving the advantages of using optical laser sensors for DA detection in complex samples.