Python-driven impedance profiling on peptide-functionalized biosensor for detection of HIV gp41 envelope protein

Abstract

This study presents the first label-free impedimetric biosensor for the detection of HIV envelope protein gp41 using antimicrobial peptides (AMPs) as biorecognition receptors. The biosensor interface was enhanced with thiolated polystyrene and gold nanospheres to ensure stable peptide immobilization and resist nonspecific adsorption. Electrochemical impedance spectroscopy (EIS) confirmed each step of the electrode modification, while surface morphology was validated via scanning electron microscopy. A Python-based deep learning algorithm was applied to impedance data for efficient curve fitting and regression modeling. The biosensor demonstrated high sensitivity, with a linear detection range of 5-600 pg/mL, a regression coefficient (R ²) of 0.9946, a limit of detection (LOD) of 1.62 pg/mL, and a limit of quantification (LOQ) of 4.91 pg/mL. Chronoimpedimetric (CI) detection revealed that gp41 binding occurred within 350 s. The biosensor showed excellent reproducibility (CV % = 0.22%), good selectivity with less than 12% signal variation in spiked serum, and robust stability, maintaining functionality after extended storage. These results highlight the biosensor's potential as a rapid, sensitive, and reproducible diagnostic platform for early HIV detection.

Supplementary information: The online version contains supplementary material available at 10.1007/s13205-025-04400-8.

Keywords: Biosensor; Gp41; HIV; Impedance; Python.

Fig. 1

Schematic illustration of the fabrication process of the HIV gp41 impedimetric biosensor

Fig. 2

Electrochemical impedance spectroscopy (EIS) results showing biosensor surface modification. Nyquist plots represent the impedance behavior of (red) the bare carbon electrode, (blue) the electrode modified with PS-AuNP composite, and (yellow) the AMP-functionalized biosensor. The increasing diameter of semicircles corresponds to increasing charge transfer resistance (Rct), confirming successful surface functionalization at each stage

Fig. 3

Surface morphology of the biosensor at different modification stages, characterized by SEM. A Bare carbon electrode. B Electrode modified with polystyrene–gold nanoparticles at 1000 × magnification, showing a homogeneous nanoparticle layer. C Electrode at 5000 × magnification, revealing dispersed gold nanoparticles embedded in the polystyrene matrix, providing anchoring sites for peptide immobilization

Fig. 4

Chronoimpedimetric detection of HIV gp41 protein in serum. The plot shows real-time impedance changes over 800 s using biosensors in (red) blank buffer and (black) serum spiked with 80 pg/mL gp41. A significant rise in impedance is observed in the gp41-spiked sample around 350 s, indicating successful binding and detection

Fig. 5

Calibration performance of the biosensor for HIV gp41 detection. A EIS spectra collected after exposure to increasing concentrations of gp41 (5–600 pg/mL). B Calibration curve based on the fitted impedance values (Rct) versus concentration, showing excellent linearity (R² = 0.9946). The detection limit (LOD) and quantification limit (LOQ) were calculated as 1.62 pg/mL and 4.91 pg/mL, respectively

Fig. 6

Biosensor performance in real serum samples: selectivity and repeatability. Biosensors were tested with varying gp41 concentrations (including low and high concentrations within the calibration range). The results demonstrate consistent response across multiple sensors and minimal matrix effect, confirming the biosensor’s robustness in complex biological samples

Fig. 7

Storage stability of the biosensor under different conditions. Biosensors stored at room temperature (R.T.) and + 4 °C were tested after a defined period using a 50 pg/mL gp41-spiked sample. The performance was compared to freshly prepared sensors (t = 0). The biosensors stored at room temperature exhibited better long-term stability, likely due to the hydrophobic nature of the polystyrene–gold matrix