Fig. 1: Zwitterionic nanoplasmonic bio-mesh fabrication, characterization, and antifouling demonstration.

A Schematic illustration of the zwitterionic nanoplasmonic bio-mesh fabrication process, highlighting the use of reverse nanoimprint lithography and the mechanism by which L-cysteine self-assembled monolayers on nanolaminated plasmonic nanoantennas (NLPNAs) confer antifouling properties. B Visual and microscopic characterization of zwitterionic nanoplasmonic bio-meshes: Oblique-angle and top-down camera images showcasing macroscopic features, top-down bright-field and SEM images revealing surface morphology, and cross-sectional SEM image alongside a schematic illustrating the NLPNA structure. C Experimental timeline depicting the sequential exposure of SERS devices to serum, water, and R6G-spiked serum, with green regions indicating active SERS measurement periods. D Comparative ERS-normalized SERS spectra of L-cysteine-functionalized and bare SERS devices in serum, water, and R6G-spiked serum, highlighting the impact of L-cysteine on protein fouling and R6G detection. Shaded regions represent standard deviations from 50 individual spectra. E Time-resolved ERS-normalized intensities of characteristic Raman peaks for serum protein (1245 cm⁻¹) and R6G (1507 cm⁻¹) in different solutions, further demonstrating the antifouling efficacy of L-cysteine functionalization. Error bars represent standard deviations from 50 datapoints. *** represents p values < 0.001, indicating statistically significant difference. F Time-resolved 2D maps of the characteristic ERS-normalized Raman peak for serum protein (1245 cm⁻¹) in different solutions.