Amperometric biosensors have been studied for applications in a wide range of medical and environmental monitoring contexts since first being reported 50 years ago. They are typically made up of two components: a biorecognition element that can specifically interact with the analyte in question, and a transduction element that produces a robust electrical current that correlates with the concentration of analyte in the sample. In many amperometric biosensing configurations, both components must be able to directly interface with the working electrode, necessitating direct functionalization of the electrode interface. Functionalization is most commonly achieved via some sort of organic film that is capable of adsorbing on the working electrode. This presents a distinct challenge, as the...[ Read more ]

Amperometric biosensors have been studied for applications in a wide range of medical and environmental monitoring contexts since first being reported 50 years ago. They are typically made up of two components: a biorecognition element that can specifically interact with the analyte in question, and a transduction element that produces a robust electrical current that correlates with the concentration of analyte in the sample. In many amperometric biosensing configurations, both components must be able to directly interface with the working electrode, necessitating direct functionalization of the electrode interface. Functionalization is most commonly achieved via some sort of organic film that is capable of adsorbing on the working electrode. This presents a distinct challenge, as the characteristics of an organic film can influence a number of factors that affect the sensitivity and selectivity of a biosensor. This is compounded by the high ionic strength matrices that many relevant analytes are found within. To investigate these factors, this thesis examines several self-assembled monolayers for their functionalization with tetrodotoxin, a potent marine toxin. Using the findings, an amperometric biosensor is developed and characterized using tetrodotoxin specific monoclonal antibodies immobilized on a gold electrode surface with a 6-mercaptohexanol derived self-assembled monolayer. Bovine serum albumin is shown to have a stabilizing effect on the biorecognition layer in seawater matrices, improving repeatability and decreasing nonspecific adsorption. The sensor is able to detect picomolar concentrations of the toxin in seawater samples in under an hour. Finally, a conductive polymer nanocomposite is characterized and employed for the detection of vitamin C, achieving high sensitivity and repeatability with a simple and scalable electrodeposition synthesis. The findings presented here have implications for medical and environmental monitoring applications, advancing the capabilities of amperometric biosensors for improved detection of small molecule analytes.