Label-Free Aptasensor for Lysozyme Detection Using Electrochemical Impedance Spectroscopy

Abstract

This research develops aptasensors for Lysozyme protein detection [1] using the Electrochemical Impedance Spectroscopy (EIS) technique which is simple, low-cost and follows the rapid highsensitivity transduction principle to monitor biosensing events that take place at the surface of an electrode; the EIS technique is also capable of showing responses at a very low concentration level [2]. To achieve the main objective of this work, electrodes based on Graphite-Epoxy Composite (GECs) were constructed. The chosen immobilization technique was covalent bond using carbodiimide chemistry; for this purpose, carboxylic moieties were first generated on the graphite by electrochemical grafting.The detection is performed using [Fe(CN)6] 3− /[Fe(CN)6] 4− as the redox marker. After recording the frequency response, values are fitted to its electric model; for this purpose, a nonlinear leastsquares regression protocol with complex arithmetic using Z-view is performed using the principles of the equivalent circuit. The aptasensor showed a linear response range of 0.25 μM-5 μM for Lysozyme and a limit of detection (LOD) of 0.19 μM. The sensitivity of the method established was 0.0889 μM −1 in relative charge transfer resistance values.The aptasensor can be regenerated by breaking the complex formed between the aptamer and Lysozyme using 2.0 M NaCl solution at 42 °C, showing its operation for five cycles. The main proteins' interference response, such as bovine serum albumin (BSA) and Cytochrome c (Cyt c), has also been characterized. To finally verify the performance of the developed aptasensor, it was applied to wine analysis. The developed aptasensors indicate their suitability given that they can detect Lys in a complex matrix such as wine obtaining recovery yields of 77%.

Impact of nano-morphology, lattice defects and conductivity on the performance of graphene based electrochemical biosensors

“…Charge transfer resistance responsiveness to analyte concentrations yielded sensitive impedance biosensors [24]. For example, the impedimetric label-free aptamer biosensor for lysozyme detection showed a limit of detection (LOD) of 1.67 µM, a linear response up to 5 µM, and a sensitivity of 0.090 µM −1 in relative charge transfer resistance values [25]. Electrochemical transducers provide an attractive means of converting a biological event to an electric signal.…”

Challenges and Applications of Impedance-Based Biosensors in Water Analysis

“…In addition to blocking agents, antifouling agents can be used to prevent target depletion via non-specific bindings [46]. Blocking agent reduces the non-specific binding by blocking the active functional groups on the surface and can stabilize the biomolecule bound to the surface [47].…”

“…Antifouling (or non-fouling) agent is Challenges and Applications of Impedance-Based Biosensors in Water Analysis DOI: http://dx.doi.org/10.5772/intechopen.89334 a compound that has the capability to ensure the resistivity to the non-specific adsorption of proteins, cells, or other biological species [48]. Ortiz-Aguayo and Valle tried to decrease the non-specific adsorption to the graphite-epoxy composite electrode surface of an EIS-based wine aptasensor using polyethylene glycol [46]. Even though the aptasensor showed good sensitivity, the blocking did not work so efficiently; and the recovery was approximately 77%.…”

Interfacing aptamers, nanoparticles and graphene in a hierarchical structure for highly selective detection of biomolecules in OECT devices

“…Our approach, taking advantage of an AuNPs-PMLG composite, is also reinforced by the choice of a novel sensing parameter, the , a parameter expressing the relative change of drain-source current for Thrombin concentration, that is expected to give a direct correlation between the binding events and the channel current change 30 . The use of the parameter allows excluding spurious effects due to single components of the fabricated aptasensor, such as aptamers, graphene and AuNPs 31 .…”