Potentiometric Biosensor Based on Artificial Antibodies for an Alzheimer Biomarker Detection

Abstract

This paper presents a potentiometric biosensor for the detection of amyloid β-42 (Aβ-42) in point-of-care analysis. This approach is based on the molecular imprint polymer (MIP) technique, which uses covalently immobilised Aβ-42 to create specific detection cavities on the surface of single-walled carbon nanotubes (SWCNTs). The biosensor was prepared by binding Aβ-42 to the SWCNT surface and then imprinting it by adding acrylamide (monomer), N,N’-methylene-bis-acrylamide (crosslinker) and ammonium persulphate (initiator). The target peptide was removed from the polymer matrix by the proteolytic action of an enzyme (proteinase K). The presence of imprinting sites was confirmed by comparing a MIP-modified surface with a negative control (NIP) consisting of a similar material where the target molecule had been removed from the process. The ability of the sensing material to rebind Aβ-42 was demonstrated by incorporating the MIP material as an electroactive compound in a PVC/plasticiser mixture applied to a solid conductive support of graphite. All steps of the synthesis of the imprinted materials were followed by Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR). The analytical performance was evaluated by potentiometric transduction, and the MIP material showed cationic slopes of 75 mV-decade−1 in buffer pH 8.0 and a detection limit of 0.72 μg/mL. Overall, potentiometric transduction confirmed that the sensor can discriminate Aβ-42 in the presence of other biomolecules in the same solution.

Recent Advances in Molecularly Imprinted Polymers and Their Disease-Related Applications

“…Before polymerization, the carbon nanotubes were oxidized to provide reactive points for the covalent immobilization of β-amyloid 1-42. The imprinting step yielded imprinted carbon nanotubes that were afterward embedded in PVC membranes deposited on a graphite electrode [90]. Both studies proved good selectivity for β-amyloid 1-42 in plasma.…”

Development of Two-Dimensional Functional Nanomaterials for Biosensor Applications: Opportunities, Challenges, and Future Prospects

“…Field-effect transistors (FETs) form the basis of many potentiometric devices. It is commonly used to detect changes in pH, ion concentrations, and the rate of enzyme-catalyzed biocatalytic reactions [129].…”

Biosensors: Types, Applications, and Future Advantages

“…A standard graph is obtained by determining the values of the various concentrations of the substance to be studied. The range in which linear increase is observed in graphic interpretation is determined as the measurement range [95].…”

“…Repeatability is observed by calculating the variation coefficients and standard deviations of the values taken [94]. As a result of the measurements made, it is determined whether the standard deviation and variation coefficients calculated, and the biosensors are reusable [95]. The variation coefficient must be less than 5% to prove that the biosensor system is workable [58].…”