Sensitive and selective Affimer-functionalised interdigitated electrode-based capacitive biosensor for Her4 protein tumour biomarker detection

Abstract

A novel Affimer-functionalised interdigitated electrode-based capacitive biosensor platform was developed for detection and estimation of Her4, a protein tumour biomarker, in undiluted serum. An anti-Her4 Affimer with a C-terminal cysteine was used to create the bio-recognition layer via self-assembly on gold interdigitated electrodes for the sensor fabrication. Electrochemical impedance spectroscopy (EIS) in the absence of redox markers was used to evaluate the sensor performance by monitoring the changes in capacitance. The Affimer sensor in buffer and in undiluted serum demonstrated high sensitivity with a broad dynamic range from 1 pM to 100 nM and a limit of detection lower than 1 pM both in buffer and in serum. Furthermore, the Affimer sensor demonstrated excellent specificity with negligible interference from serum proteins, suggesting resilience to non-specific binding. The sensing ability of the present Affimer sensor in spiked undiluted serum suggests its potential for a new range of Affimer-based sensors. The fabricated Affimer sensor can thus be further adapted with other probes having affinities to other biomarkers for a new range of biosensors.

A review on impedimetric immunosensors for pathogen and biomarker detection

“…Affimers are a non-antibody scaffolds considered as a good alternative as a binding protein [44]. An impedimetric biosensor based on Affimer binding bioreceptor was used to detect and quantify Her4 protein tumour, getting an LOD lower than 1 pM in less than 30 min of sample incubation [112].…”

Electrochemical Impedance Spectroscopy Based Biosensors: Mechanistic Principles, Analytical Examples and Challenges towards Commercialization for Assays of Protein Cancer Biomarkers

“…A novel Affimer‐functionalized interdigitated electrode‐based capacitive biosensor platform was developed for the detection and estimation of Her4 in undiluted serum . The Affimer sensor exhibits high assay sensitivity with a wide dynamic range (from 1 pM to 100 nM) and LOD lower than 1 pM in both a buffer and in serum …”

Recent Progress of Biomarker Detection Sensors

“…Aydın et al decorated the ITO electrode with composite material (carbon black and PGMA polymer) for anti-IL-8 antibody immobilization and then fabricated a high-sensitivity label-free biosensor for IL-8 detection [ 36 ]. Taking advantage of the excellent specificity with negligible interference from the serum of Affimer proteins, Zhurauski et al developed an Affimer-based electrochemical biosensor for Her4 detection combined with non-Faradaic impedance and ID μ Es [ 37 ]. Seenivasan et al developed a prostate-specific membrane antigen (PSMA) sensor, in which gold nanoparticles (GNPs) functionalized with PSMA antibodies (PSMA-Ab) were decorated onto patterned electrodes (ITO-coated glass) to improve the limit of detection [ 38 ].…”