High Sensitivity Sensor for C-Reactive Protein Detections

Abstract

Among the various type of sensor strucrures, cyclic voltammetry (CV), chronoamperometry, impedance spectroscopy, and various methods based on ion sensitive field effect transistors (ISFET) in combination with modern low-dimensional systems are very popular. ISFET sensors show a high signal-to-noise ratio, high measurement speed, compactness and portability. This work is dedicated to development sensor to detect C-reactive protein (CRP) based on ISFET. CRP - inflammatory protein that dramatically increases during the inflammatoryduring inflammatory.For the first time, a multilayer structure for the C-reactive protein detection was proposed, using a sensor based on the CeO2 ISFET as a sudgate dielectric and n-type field-effect transistor as a platform. For this sensor, the limit of detection at 0.1 mg/L and the sensitivity at 290 mV/(mg/L) were established. For this analysis should be only 20 μl of the reagent and about 1 min of time was needed. The developed sensor showed good stability in work for 30 days. Another interesting feature of this sensor was observed. It can work not just with standard test kits, but also in real human blood serum. The response of the sensor on real blood serum samples was just 18% less than the results from the calibrations antigen CRP concentrations for the standard test kit at the enzyme-linked immunosorbent assay.To increase the sensitivity the additional buffer layer - melanin was used. Such layer increased the sensor sensitivity by almost 61%.To get good and stable results the experiment was carried out at the stable ambient conditions: temperature ~ 20°C and at the same level of illumination (put sensor in dark box).The performance of the biosensor is influenced not just by the antibody concentration and also by the incubation time of CRP. During incubation, the antigen antigen-antibody complex is formed. It takes some time to get this complex on the sensor working surface. With an increasing incubation time, the current response decreases and stabilizes after ~0.5 hourds. To obtain the optimal current response the incubations time of 30 min was found.In conclusion, such results of CRP sensor based on ISFET with CeO2 as gate dielectric are the basis for using this sensor in real clinical trials, particularly for screening trials. Figure 1