Nanomaterial-Based Enzymatic Biosensor for p-Cresol Detection as an Early Autism Spectrum Disorder Diagnosis Biomarker.

Neurodevelopmental disorders are cognitive and behavioral disorders that involve significant difficulties in the acquisition and execution of specific motor, intellectual, social or language functions, including disorders like autism spectrum disorder (ASD). To date, the diagnosis of ASD has been based on observation of daily functionality and behavioral characteristics of patients, and the standards for this diagnosis are complex, time-consuming and unpractical. Diagnosis based on biomarkers detection could be a good alternative. In this work, we propose an innovative electrochemical strategy for the detection of an ASD-related biomarker, p-cresol. A simple, rapid, and sensitive enzymatic sensing platform was developed based on mechanically interlocked derivatives of single-walled carbon nanotubes and tyrosinase properties. This enzyme catalyzes the oxidation of p-cresol by molecular oxygen, converting it to quinone, which can be electrochemically reduced to allow convenient low potential detection. The platform was optimized, characterized, and demonstrated excellent electrooxidation properties. This device detects p-cresol from 100 pM to 10 μM and achieved an outstanding detection limit of 11.1 pM. It presented high specificity in the presence of potential interfering compounds, maintained its functionality after 45 days of storage, and has been validated using human urine samples of children with ASD.