Ultrasensitive Detection and In Situ Imaging of Analytes on Graphene Oxide Analogues Using Enhanced Raman Spectroscopy

We demonstrate how algorithm-improved confocal Raman microscopy (ai-CRM), in combination with chemical enhancement by two-dimensional substrates, can be used as an ultrasensitive detection method for rhodamine (R6G) molecules adsorbed from aqueous solutions. After developing a protocol for laser-induced reduction of graphene oxide, followed by noninvasive Raman imaging, a limit of detection (LOD) of 5 x 10(-10) M R6G was achieved using ai-CRM. An equivalent subnanomolar LOD was also achieved on another graphene oxide analogue -UV/ozone-oxidized graphene. These record-breaking detection capabilities also enabled us to study the adsorption kinetics and image the spatial distribution of the adsorbed R6G. These findings indicate a strong potential for algorithm-improved graphene-enhanced Raman spectroscopy as a facile method for detecting, imaging, and quantifying trace amounts of adsorbing molecules on a variety of 2D substrates.

Automated summary

This study demonstrates the ultrasensitive detection of R6G molecules adsorbed from aqueous solutions using algorithm-improved confocal Raman microscopy and chemical enhancement by two-dimensional substrates. By developing a protocol for laser-induced reduction of graphene oxide and noninvasive Raman imaging, subnanomolar limits of detection were achieved on various substrates, allowing for the study of adsorption kinetics and imaging of spatial distribution. The findings suggest a strong potential for algorithm-improved graphene-enhanced Raman spectroscopy as a convenient method for detecting, imaging, and quantifying trace amounts of adsorbing molecules on different 2D substrates.