This work presents a thorough electrochemical and reliability analysis of a sensing scheme for the
antipsychotic clozapine. We have previously demonstrated a novel detection approach for this redox-active
drug, highly effective in
schizophrenia treatment, based on a
catechol-modified
chitosan film. The
biomaterial film enables amplification of the oxidative current generated by
clozapine through redox cycling. Here, we study critical electrochemical and material aspects of the redox cycling system to overcome barriers in point-of-care monitoring in complex
biological samples. Specifically, we explore the electrochemical parameter space, showing that enhanced sensing performance depends on the presence of a reducing mediator as well as the electrochemical technique applied. These factors account for up to 1.75-fold and 2.47-fold signal enhancement, respectively. Looking at potential interferents, we illustrate that the redox cycling system allows for differentiation between selected redox-active species,
clozapine's structurally largely analogous metabolite
norclozapine as well as the representative
catecholamine dopamine. Furthermore, we investigate material stability and fouling with reuse as well as storage. We find no evidence of film fouling due to
clozapine; slow overall
biomaterial degradation with successive use accounts for a 2.2% absolute signal loss and can be controlled for. Storage of the redox cycling system appears feasible over weeks when kept in
solution with only 0.26%/day
clozapine signal degradation, while ambient air exposure of three or more days reduces performance by 58%. This study not only advances our understanding of the
catechol-modified
chitosan system, but also further establishes the viability of applying it toward sensing
clozapine in a clinical setting. Such point-of-care monitoring will allow for broader use of
clozapine by increasing convenience to patients as well as medical professionals, thus improving the lives of people affected by
schizophrenia through
personalized medicine.