Lab-on-a-Molecule elaboration for fluorescence based discrimination of commercial surfactants sodium dodecyl sulfate and sodium dodecylbenzenesulfonate

- NAAN-3 undergoes 40-50 times increase in FI with one equivalent of SDS and SDBS.
- NAAN-3 with SDS and SDBS elicits new emission bands respectively at 470 and 540 nm.
- NAAN-3 elaborates Lab-on-a-molecule concept.
- NAAN-3 allows simultaneous determination of SDS and SDBS from tap water and urine.
- LOD for SDS and SDBS is 10 and 20 nM, respectively.

The nicotinamide-anthracene conjugates NAAN-1 to NAAN-4, possessing C8, C10, C12 and C14 alkyl chain on amide nitrogen of nicotinamide moiety result in discriminative recognition of SDS and SDBS. Amongst these probes, NAAN-3 (with C12 alkyl chains) is most sensitive and selective to both SDS and SDBS and on addition of SDS or SDBS elicits new emission band respectively at 470 (fluorescence bluish-green) and 540 nm (fluorescence greenish-yellow), with similar increase (40-50 times) in fluorescence intensity, resulting in discriminative recognition of SDS and SDBS. NAAN-3 can determine as low as 2.8 parts per billion (10 nM) SDS or 5.8 parts per billion (20 nM) SDBS from water and urine samples. NAAN-3 elaborates lab-on-a-molecule concept and can be used for fluorescence based simultaneous determination of SDS and SDBS from their mixtures by measuring fluorescence intensity at 470 and 540 nm, respectively. The formation of ionic self-assembly by these probes with SDS and SDBS has been unequivocally proved by DLS and FE-SEM studies and their discriminative binding has been supported by DFT studies.

Self-assembly of NAAN-3 with SDS and SDBS results in different fluorescence colors and allows simultaneous detection of SDS and SDBS with respective 10 nM and 20 nM limits of detection.177