Electrochemical Immunosensor for the Quantification of S100B at Clinically Relevant Levels Using a Cysteamine Modified Surface

Abstract

Neuronal damage secondary to traumatic brain injury (TBI) is a rapidly evolving condition, which requires therapeutic decisions based on the timely identification of clinical deterioration. Changes in S100B biomarker levels are associated with TBI severity and patient outcome. The S100B quantification is often difficult since standard immunoassays are time-consuming, costly, and require extensive expertise. A zero-length cross-linking approach on a cysteamine self-assembled monolayer (SAM) was performed to immobilize anti-S100B monoclonal antibodies onto both planar (AuEs) and interdigitated (AuIDEs) gold electrodes via carbonyl-bond. Surface characterization was performed by atomic force microscopy (AFM) and specular-reflectance FTIR for each functionalization step. Biosensor response was studied using the change in charge-transfer resistance (Rct) from electrochemical impedance spectroscopy (EIS) in potassium ferrocyanide, with [S100B] ranging 10–1000 pg/mL. A single-frequency analysis for capacitances was also performed in AuIDEs. Full factorial designs were applied to assess biosensor sensitivity, specificity, and limit-of-detection (LOD). Higher Rct values were found with increased S100B concentration in both platforms. LODs were 18 pg/mL(AuES) and 6 pg/mL(AuIDEs). AuIDEs provide a simpler manufacturing protocol, with reduced fabrication time and possibly costs, simpler electrochemical response analysis, and could be used for single-frequency analysis for monitoring capacitance changes related to S100B levels.

TBISTAT: An open-source, wireless portable, electrochemical impedance spectroscopy capable potentiostat for the point-of-care detection of S100B in plasma samples

“…Similar to the high-pass filter circuit used in the AC excitation signal design module, a 3.3/2 V VGV is fixed on the positive input of the TIA via a simple voltage divider circuit. This circuit ensures low DC bias between the input excitation signal and output voltage of the TIA, which is a sufficient condition for EIS of the ANTI-S100B functionalized AUIDEs to detect S100B, as seen in Rodriguez et al [ 38 ]. The TIA voltage signal passes through a fourth-order 10 KHz SKLPF for high-frequency noise filtering using an LMP7702 OAMP IC.…”

“…The TIA voltage signal passes through a fourth-order 10 KHz SKLPF for high-frequency noise filtering using an LMP7702 OAMP IC. The cutoff frequency is determined following the EIS measurement specifications established by Rodríguez et al [ 38 ] for S100B detection, and the ADC conversion is performed using the MCU ADC. Additional details about the PC design are found in S1 File .…”

“…Validation was done using two methods: Visual comparison of impedance magnitude and phase responses along the EIS frequency range obtained by TBISAT and an Autolab/M204 benchtop potentiostat/galvanostat (Metrohm®) equipped with an Autolab® FRA32 module controlled by the NOVA 2.11 software, and a T-test statistical comparison between ΔC results at f = 31.6 Hz obtained by TBISAT and the benchtop potentiostat. Capacitance was obtained from EIS scans following the method described by Rodriguez et al [ 38 ]. The statistical analysis was done using Statgraphics Centurion 18.…”

Antibody-labeled gold nanoparticle based resonance Rayleigh scattering detection of S100B

“…Regarded as a TBI biomarker, S100B has been shown to correlate with injury magnitude, survival and neurological outcome. 5 Existing S100B assays include enzyme-linked immunosorbent assay (ELISA), 6 magnetic bead quantum dot assay, 7 SPR sandwich photoelectrochemical immunoassay, 8 electrochemical assay, 9 paper lateral ow strips (PLFS), 10 peptide-modied ratiometric uorescent nanoprobes, 11 and colloidal gold-based immunochromatographic biosensors. 12 In the clinical setting, biomarker measurement requires a technique that is easy to use, readily available, inexpensive and responsive.…”

Microfluidic Paper-Based Blood Plasma Separation Device as a Potential Tool for Timely Detection of Protein Biomarkers

“…Previous work from our research group has described the development of electrochemical biosensors for the quantification of S100B in plasma with a benchtop potentiostat [ 7 ] and a developed portable potentiostat for POC detection [ 8 ]. However, in the clinical context, the measurement of this biomarker demands a technique that is easy to use, readily available, low-cost, and with a fast response time.…”