Development of a silver–polyaniline functionalized biosensor for non-enzymatic lactic acid detection

Sensor research based on biometal performance and health parameter detection attracts significant global interest in the biosensing community. In this study, an electrochemical biosensor has been developed for the detection of lactic acid (LA) in artificial saliva, and in this context, the screen-printed electrode was functionalized using a composite of silver nanoparticles (AgNPs) and silver nanoparticles–polyaniline (AgNPs–PANI). The cyclic voltammetry responses were recorded for non-enzymatic LA sensing. In this process, the electro-polymerization method has been used to generate a film of Ag–PANI on a screen-printed electrode (SPE). Several analytical techniques, including Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-visible), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and RAMAN spectroscopy, were employed to analyze the film of AgNPs and AgNPs–PANI that was used to change the surface morphology of the screen-printed electrode (SPE). The various important parameters of effectiveness viz., limit of detection (LOD) and limit of quantification (LOQ) for AgNPs–SPE and AgNPs–PANI–SPE were investigated and were found to be in the range of 5.3 mM, 16 mM and 2.5 mM, 7.4 mM, respectively, in PBS solution. Meanwhile, for the artificial saliva samples, the sensitivity of the AgNPs–PANI–SPE was obtained up to 0.00176 mA μM⁻¹ cm⁻² with an LOD of 0.76 mM. Furthermore, DFT results are used to examine the physical and electrical properties of the prepared functional films. The computing results show the functionalization of carbon with AgNP and AgNP–PANI, enabling a stable and reactive structure. The current research offers a non-enzymatic technique for precisely detecting LA biomolecules for medical applications.