The global propagation of environmental biocontaminants such as antibiotic resistant pathogens and their antibiotic resistance genes (ARGs) is a public health conc that highlights the need for improved monitoring strategies.Here,we demonstrate the environmental stability and applicability of an oligonucleotide-functionalized gold nanosensor.The mecA ARG was targeted as model biocontaminant due to its presence in clinically-relevant pathogens and to its emergence as an environmental contaminant.mecA-specific nanosensors were tested for antibiotic resistance gene (ARG) detection in ARG-spiked effluent from four wastewater treatment plants (WWTPs).The mecA-specific nanosensors showed stability in environmental conditions and in high ionic strength ([MgCl2] ＜ 50 mM),and high selectivity against mismatched targets.Spectrophotometric detection was reproducible with an LOD of 70 pM (≈4 × 107 genes/μL),even in the presence of interferences associated with non-target genomic DNA and complex WWTP effluent.This contribution supports the environmental applicability of a new line of cost-effective,field-deployable tools needed for wide-scale biocontaminant monitoring.