Cotinine, a metabolite of nicotine, has shown promise as a biomarker for the detection of tobacco use and smoke exposure due its ability to persist in human bodily fluids for days (ca. 4-5 days) after tobacco consumption. However, current cotinine detection strategies primarily include arduous laboratory sensing methods or qualitative in-field biosensing devices. Herein, we report an electrochemical cotinine sensor based on a selective molecularly-imprinted polymer (MIP) electrodeposited on a screen-printed carbon electrode (SPCE) modified with graphene flakes and platinum nanoparticles (PtNPs). The PtNP-graphene modified SPCE exhibited a 4-fold increase in electrochemical sensitivity (10 µA to 40 µA) during ferryicyanide cyclic voltammetry. This developed biosensor functionalized with the MIP was consequently capable of selective sensing of cotinine in spiked saliva samples across a wide sensing range (1-100 nM) and low detection limit of (0.33 nM). This sensing range covers cotinine concentration levels that are typically found in saliva for non-smokers and smokers (ca. 10 – 75 nM). Moreover, the sensing is capable of acquiring a cotinine measurement within 12 minutes with minimal interference from both nicotine and myosmine–cotinine chemical analogs that are typically found in tobacco products. Hence, the developed biosensor is well-suited for use in the field such as at point-of-care facilities.
Available at: http://works.bepress.com/jonathan_claussen/45/