Environmentally Safe Mercury (II) Ions Aided Zero-Background and Ultrasensitive SERS Detection of Dipicolinic Acid

Field, reliable and ultrasensitive detection of dipicolinic acid (DPA), a general biomarker of bacterial spores and especially Bacillus anthracis, is highly desirable but still challenging in current biometric security emergency response system. Herein we report an environmentally safe mercury (II) ions-mediated and competitive coordination interaction based approach for rationally designed surface-enhanced Raman scattering (SERS)-active gold nanoparticles (AuNPs), enabling rapid, ultrasensitive and zero-background detection of DPA without the pretreatment of samples. By means of competitiveness, these papain capped gold nanoparticles (P-AuNPs) are induced to undergo controllable aggregation upon the addition of Hg2+ ions and DPA with a concentration range (1 nM~8 μM), which correspondingly cause quantitative changes of SERS intensity of cresyl violet acetate (CVa) conjugated AuNPs. The decreased Raman intensity obtained by subtracting two cases of additives that contain only Hg2+ and the mixture of Hg2+ ...