The immobilization efficiency of anti-CRP nanobodies is a crucial step for achieving high antigen binding specificity. To achieve this, the hydroxyl functional groups of the oxidized electrode were first modified to incorporate aldehyde groups through an oxidation reaction. Anti-CRP nanobodies were subsequently immobilized on the oxidized electrode through an imine bond (C=N). To validate the process and assess the nanobody binding capacity for CRP target, two analytical techniques were employed: electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). These techniques make it possible to discriminate small variations at the interface between electrode and electrolyte, as well as to assess the electron transfer efficiency of the redox couple ([Fe(CN6)] 3-/4-). The EIS Nyquist plot was fitted using the Randles equivalent circuit, as shown in Fig. . The bare SPGE ( dashed line) showed low electron-transfer resistance (or high charge transfer resistance, denoted as high Rct), indicating lower conductivity compared to the anodized electrode (blue line). However, the introduction of the anti-CRP nanobodies (green line) onto the electrode surface induced a noticeable increase of the Rct value. This observed increase strongly supports the successful immobilization of the immunocapture nanobody reagent E12. After biosensor coating with casein (yellow line), the subsequent addition of CRP (red line) triggered a significant Rct increment. These results suggest that the immunocomplex formed between anti-CRP nanobodies and CRP affected the electron transfer of the redox solution at the electrode interface. EIS results are consistent with CV results, as shown in Fig. . Specifically, the current response was progressively reduced from Ipa = 93.7 ± 3.2 μA of the anodized electrode ( blue line) to Ipa = 45.8 ± 4.6 μA of the CRP signal ( red line) at each successive modification step, indicating the corresponding interference of electron transfer. Both the EIS and CV results indicated the successful nanobody immobilization on the electrode surface and their capacity to capture CRP. Furthermore, CC was employed to quantify CRP using the NFC potentiostat. As presented in Fig. , CRP quantification was obtained by measuring the peak area or the change in charge (∆Q). The ∆Q values obtained from NFC and a conventional potentiostat using various CRP concentrations were plotted (Fig. ) and resulted in good agreement ( R 2 = 0.9982) between the two potentiostats, highlighting the potential of the NFC potentiostat as a POC diagnostic tool.