Lipase Detection Using a Nanostructured Graphitic-Carbon Nitride-Based Flexible Organic Field Effect Transistor

Lipase is an enzyme that plays a critical role in the human body in digestion and the release of hormones regulating blood sugar, which are termed exocrine and endocrine functions, respectively. Estimation of lipase in the blood enables the diagnosis of pancreatic diseases such as pancreatitis, cystic fibrosis, Crohn’s disease, and celiac disease. In the present work, we report lipase detection through an organic field effect transistor (OFET) based on graphitic carbon nitride (g-C 3 N 4 ). The enzymatic hydrolysis of triglycerides by lipase on the g-C 3 N 4 surface generates glycerol and fatty acids. The nanostructured nature of g-C 3 N 4 facilitates the enhancement of the OFET’s electrical properties by improving charge carrier mobility, reducing trap states, increasing capacitance, and stabilizing charge carriers. These enhancements lead to an increase in the drain-source current ( I DS ), with increasing lipase concentrations opening up the possibility of lipase sensing. The fabricated OFET exhibits impressive electronic properties, including an average saturation mobility of 83.6 × 10 –3 cm 2 V –1 s –1 and ON/OFF current ratios of 1.03 × 10 3, 1.5 × 10 3, 1.8 × 10 3, and 2.4 × 10 3 at gate voltages of 0, 0.2, 0.4, and 0.6 V respectively. The device is found to be highly sensitive to lipase concentrations ranging from 100 to 500 U/L with a linearity coefficient ( R 2 ) of 0.994 and a limit of detection (LOD) of 0.025 μL/mL. The device’s reproducibility and repeatability as evidenced by a relative standard deviation (RSD in percentage) of approximately 1.24% further highlight its precision and reliability. These findings underscore the potential of g-C 3 N 4 -based OFETs as effective, cost-efficient, and easy-to-fabricate biosensors for clinical diagnostics and flexible electronic applications.