Fig. 4: In situ analyte switching.

a Sequential SERS spectra from alternating detection of 100 µM ADN (red) and 100 µM CYT (blue) with the corresponding regenerated MLagg-CB[5] (black). A 50:50% mixture of 100 µM ADN and 100 µM CYT (purple) is also tested. b Normalized peak areas of ADN (\({\nu }_{{{{{{\rm{ADN}}}}}}}\) = 732 cm⁻¹, red) and CYT (\({\nu }_{{{{{{\rm{CYT}}}}}}}\) = 792 cm⁻¹, blue) per detection-regeneration cycle. c Sequential spatially-averaged SERS spectra from alternating detection of 100 µM ADN (red) and 100 µM 4-biphenylthiol (BPT), 4,4-biphenyldithiol (BPDT), 1,4-benzenedithiol (BDT), 2-naphthalenethiol (2-NT), and 4-mercaptopyridine (4-MPY) with the corresponding regenerated MLagg-CB[5] (black). d Normalized peak area of \({\nu }_{{{{{{\rm{ADN}}}}}}}\) per ADN/thiol detection-regeneration cycle. Peak areas are plotted as the mean with error bars representing ±1 s.d. of n = 10 spectra obtained from different points across the MLagg-CB[5] area. For cycle 6 (marked by asterisk), alternative ADN peak at 970 cm⁻¹ is used due to overlap with BDT peak at 732 cm⁻¹. e Sequential SERS spectra from detection of a series of biological compounds: ADN, CYT, hypoxanthine (HYP), creatinine (CR), nicotinamide (NAM), paracetamol (PAR), norepinephrine (NEPI), tryptophan (TRP), nicotinic acid (NIA), methylene blue (MB), and ADN (red) again with the corresponding regenerated MLagg-CB[5] (black). Time (t) axis marks progress of both analyte detection and ReSERS (30 s between each detection cycle). All SERS spectra collected a1 s integration time and with 1 mW 785 nm excitation laser.