Development of a Miniaturized Photoelectrochemical Biosensor Based on AChE for the Detection of Clinical Biomarkers and Inhibitors Associated with Choline

• Grant number: 25/10477-6
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: October 01, 2025
• End date: September 30, 2029
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Analytical Chemistry
• Principal Investigator: Sergio Antonio Spinola Machado
• Grantee: Lília Togneri Marconsini
• Host Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

Acetylcholinesterase (AChE) is a key enzyme in the regulation of cholinergic neurotransmission, whose inhibition is associated with neurological disorders and exposure to organophosphate pesticides (OPs). In light of the need for more selective and portable analytical methods, this project proposes the development and characterization of a miniaturized photoelectrochemical (PEC) biosensor based on screen-printed carbon electrodes (SPCEs). The hybrid platform will comprise carbonylated graphitic carbon nitride (c-g-C3N4), CdS quantum dots (QDs), and AChE, aiming to combine the photoelectrocatalytic properties of the nanomaterials with the high specificity of the enzyme. Detection will be carried out indirectly by monitoring thiocholine (TCh) produced from the enzymatic hydrolysis of acetylthiocholine (ATCh), targeting the detection of cholinergic biomarkers and AChE inhibitors such as OPs. The SPCEs will be fabricated by screen-printing, and the PEC cell will be developed using 3D printing to obtain a compact, low-cost device suitable for point-of-care (POC) applications. The biosensors will be characterized by ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Electrochemical analyses will be conducted using voltammetric and amperometric techniques to determine the biosensor analytical performance. The accuracy of the proposed methodology will be validated by comparison with high-performance liquid chromatography (HPLC), enabling the assessment of agreement between the methods.