A stable surface-enhanced Raman spectroscopy (SERS) platform for ultrasensitive and reproducible detection of environmental pollutants at low pH was proposed. Plasmonic gold nanoparticles (AuNPs) restrained within bacterial cellulose (BC) scaffold maintain stable at acidic conditions, avoiding the uncontrolled aggregation and flocculation often encountered in AuNP suspensions. Two hydrophobic and neutral environmental pollutants - carbamazepine (CBZ) and atrazine (ATZ) were used to test this platform. At neutral pH, no SERS signals were observed while at an acidic pH below their pK<sub>a</sub> (2.3 for CBZ and 1.7 for ATZ), strong SERS signal appeared. The reason for this drastically pH-triggered enhancement is the electrostatic association of the positively-charged amine groups of CBZ and ATZ at pH below their pK<sub>a</sub> with the negatively-charged citrate coating on AuNP surface. This specific interaction resulted in uniform molecular alignment on AuNP surface and extremely reproducible SERS spectra.

Extending SERS application to lower pH: A stable platform for environmental pollutants detection

251st National Meeting (2016)

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