Neutral Charged Immunosensor Platform for Protein-based Biomarker Analysis with Enhanced Sensitivity

Abstract

A noninvasive, highly sensitive universal immunosensor platform for protein-based biomarker detection is described in this Article. A neutral charged sensing environment is constructed by an antibody with an oppositely charged amino acid as surface charge neutralizer. By adjusting the pH condition of the testing environment, this neutral charged immunosensor (NCI) directly utilizes the electrostatic charges of the analyte for quantification of circulating protein markers, achieving a wide dynamic range covering through the whole picomole level. Comparing with previous studies on electrostatic charges characterization, this NCI demonstrates its capability to analyze not only the negatively charged biomolecules but also positively charged analytes. We applied this NCI for the detection of HE4 antigen with a detection limit at 2.5 pM and Tau antigen with a detection limit at 0.968 pM, demonstrating the high-sensitivity property of this platform. Furthermore, this NCI possesses a simple fabrication method (less than 2 h) and a short testing turnaround time (less than 30 min), providing an excellent potential for further clinical point-of-care applications.

Recent Advances on Electrochemical Biosensing Strategies toward Universal Point‐of‐Care Systems

“…Ar ecent universal electrochemical biosensing strategy divided protein analytes (based on their amino acids sequence) into two categories,positively and negatively charged targets.Aneutral charged biomolecules surface was constructed for electrochemical detection of Taup rotein and HE4 protein with asub-pico molar sensitivity ( Figure 3B). [54] Thesensing element was asingle-use gold sensor prototype. [55] Ther ecognition element was target specific antibody.T he transduction element was [Ru(NH 3 ) 6 ] 2+/3+ or [Fe(CN) 6 ] 3À/4À based redox system.…”

“…B) After antibody was immobilizedo nto the electrode, the thiol-linked charged amino acids were tethered onto the electrode to form neutral charged surface;u pon introduction of the target, correspondingly charged redox probe was applied to the surface to interact with analyte and caused the increase of electrochemical signal owing to the decrease of electron diffusion distance (Adapted from Ref. [54].C opyright 2019 American Chemical Society).…”

Recent Advances on Electrochemical Biosensing Strategies toward Universal Point‐of‐Care Systems

“…B) After antibody was immobilized onto the electrode, the thiol‐linked charged amino acids were tethered onto the electrode to form neutral charged surface; upon introduction of the target, correspondingly charged redox probe was applied to the surface to interact with analyte and caused the increase of electrochemical signal owing to the decrease of electron diffusion distance (Adapted from Ref. . Copyright 2019 American Chemical Society).…”

“…A recent universal electrochemical biosensing strategy divided protein analytes (based on their amino acids sequence) into two categories, positively and negatively charged targets. A neutral charged biomolecules surface was constructed for electrochemical detection of Tau protein and HE4 protein with a sub‐pico molar sensitivity (Figure B) . The sensing element was a single‐use gold sensor prototype .…”

Recent Developments of Electrochemical and Optical Biosensors for Antibody Detection

“…A redox probe is commonly used to enable changes on the biosensor electrode surfaces for quantification of antibodies with electrochemical analytical techniques [34][35][36][37]. Thus, quantum dots (QDs) were utilized for the detection of antibodies ( Figure 3b) [38].…”