0 × 10−20–1.0 × 10−8 M) were injected sequentially. The binding of the target

protein (BSA) to the imprinted cavities on the surface of the electrode resulted in a decrease of the registered capacitance and the change was calculated automatically by CapSenze Smart Software (CSS). In all of the analysis, the flow rate was 100 μL/min and the injected sample volume was 250 μL. The effects selleck screening library of type (phosphate and Tris–HCl buffers, 10 mM), pH (6.0–8.0) and ionic strength of the running buffer to the BSA detection were evaluated by monitoring the change of capacitance signal at the same standard concentration of BSA (1.0 × 10−10 M). In order to show the selectivity of the BSA imprinted electrode, the responses of the capacitive system against the competitive proteins HSA and IgG were monitored. The protein solutions were applied in singular manner and also, mixed solutions of HSA, IgG and BSA were studied in competitive manner. The protein concentration was 1.0 × 10−10 M for each protein during the analysis. Samples of solutions of the individual proteins were also analyzed using NIP-electrodes. BSA was detected repeatedly, using the assay cycle; equilibration-injection-regeneration,

for 70 times. The reproducibility of the assay was evaluated by monitoring the change in capacitance at the same concentration of standard BSA solution, 1.0 × 10−10 M. Proper insulation of the electrode surface is an important step in the capacitive biosensor assay [40], [41], [42], [43], [44], [45], [46] and [47]. Cyclic Lck voltammetry Erastin (CV) is the generally used method in the presence of a permeable redox couple to evaluate the degree of insulation of the electrode surface. As shown in Fig. 3, the degree of insulation increased after modification of the electrode surface with tyramine and acryloyl chloride. The density of the surface after each step increased, compared to that of the bare surface. Finally, treatment with 1-dodecanethiol reduced the redox currents substantially and the surface was completely blocked. The

cyclic voltammetry results show that the surface of the electrode is insulated well and it can be used in the subsequent capacitive measurements. The BSA imprinted electrode was placed in the electrochemical flow cell and it was connected to the automated flow-injection system. The operating conditions of the capacitive system were optimized for type, pH and ionic strength of the running buffer. For the influence of type of buffer; 10 mM phosphate and 10 mM Tris–HCl; were tested. The pH of the buffer solution was investigated in the range of 6.0–8.0. Standard BSA solutions of 1.0 × 10−10 M were prepared in each of these buffers and injected into the system. There was no significant capacitance difference between these buffers in the studied BSA concentration (Fig. 4(A)). However, phosphate buffer at pH 7.4 gave a more stable baseline and thus, the capacitance change was more clear.