| AVS 61st International Symposium & Exhibition | |
| Biomaterial Interfaces | Tuesday Sessions |
| Session BI+AS+MN+NS-TuM |
| Session: | Biosensors |
| Presenter: | Robert Dietrich, University of Maryland, College Park |
| Authors: | R. Dietrich, University of Maryland, College Park T.E. Winkler, University of Maryland, College Park H. Ben-Yoav, University of Maryland, College Park S.E. Chocron, University of Maryland, College Park E. Kim, University of Maryland, College Park D.L. Kelly, University of Maryland School of Medicine G.F. Payne, University of Maryland, College Park R. Ghodssi, University of Maryland, College Park |
| Correspondent: | Click to Email |
We present a study of atomic layer-deposited TiN and electroplated Pt black (PtB) as candidate electrode materials to replace Au in a catechol-modified chitosan redox cycling system (Fig. 1) for the electrochemical detection of the antipsychotic clozapine (CLZ). In complex biological fluids like blood, interference from other electrochemically active species is a major challenge. The choice of electrode material is critical in addressing this challenge, as surface morphology and composition may produce a stronger and more reproducible CLZ signal, while shifting that signal away from potential interferents and improving the signal-to-noise ratio. Our electrochemical characterization results indicate that TiN is superior to Au as a sensor material, with a 2.6 times higher CLZ signal and a 3.2-fold lower variability.
Identifying electrode materials with high CLZ signal-to-noise ratio will greatly aid in translating our detection approach into a point-of-care monitoring system. Such a device will reduce the burden currently associated with CLZ due to safety and efficacy monitoring requirements [1], thereby improving the quality of life for people affected by schizophrenia. Our previous work [2] has relied on gold electrodes as a substrate for our catechol-modified chitosan films. These 5×5 mm² micro-fabricated planar gold electrodes serve as controls, which we further modified here with: TiN for its inert properties; and PtB for its high surface area and potential electrocatalytic activity (Fig. 2).
The fabricated electrodes were characterized using cyclic voltammetry. Bare Au yields an oxidative CLZ peak signal of 1.06±0.20 μA, compared to 5.20±2.26 μA when coated with chitosan-catechol (Fig. 3). TiN electrodes produce a signal of 2.00±0.26 μA bare, and 13.7±0.7 μA when modified. The combination of higher signal and lower variability with the TiN is likely due to its inert chemical properties which also propagate more repeatable biomaterial modification. We observed a secondary peak with gold as well as bare TiN electrodes, likely due to interference related to chloride or oxygen. Modified TiN revealed only a single, CLZ-related peak. Results show that, as expected, signals from the bare PtB electrodes were 3370 times higher than from Au. However, they exhibited large variation between experiments, indicating the need for electroplating optimization. Testing the PtB electrodes with the chitosan-catechol film should increase both CLZ signal and resolution. Ongoing work is also focused on glassy carbon electrodes, which are expected to yield high repeatability by eliminating potential interfering oxygen signals in the redox cycling system.