Ultra-sensitive and specific detection of ascorbic acid using a laser-engraved graphene electrode modified with a molecularly imprinted polymer†

Abstract

Accurate and sensitive detection of small molecule biomarkers, such as ascorbic acid (AA), is pivotal for clinical diagnosis of various diseases. Herein, we report the development of an integrated electrochemical sensor that specifically targets and analyzes the ultra-low concentration of AA. The sensor incorporates a combination of techniques, featuring a CO₂ laser-engraved graphene (LEG) electrode that has been further enhanced through the application of molecularly imprinted poly-o-phenylenediamine (PPD). The laser-engraved approach yields a three-dimensional (3D) porous graphene network with large surface area and good conductivity, enabling sensitive detection of AA. Furthermore, the molecularly imprinted PPD layer provides a tailored recognition site for AA, enhancing the sensor's specificity towards the target molecule. The integrated PPD/LEG electrode demonstrates the capability to detect AA in the concentration range of 1 to 100 μM and 10 to 100 nM, with a limit of detection (LOD) of 1.45 nM and a limit of quantification (LOQ) of 20.44 nM. The real urine sample detection indicates that the developed PPD/LEG electrode can effectively differentiate cases in the melanoma mouse model from the healthy control group. The combination of the LEG electrode with the molecularly imprinted polymer (MIP) technique presents a novel platform for integrated sensing systems, offering unprecedented accuracy and sensitivity in the detection of small molecule biomarkers at trace concentrations. This innovation offers the potential for early clinical detection of diseases, where timely and precise measurements of biomarkers are crucial for diagnosis and treatment.