Covalent and embedment immobilization of macrocyclic polyamines on gold electrodes and their voltammetric responses towards ethene dicarboxylic acids

Recent Advantages of Mediator Based Chemically Modified Electrodes; Powerful Approach in Electroanalytical Chemistry

Background:

Modified electrodes have advanced from the initial studies aimed at understanding electron transfer in films to applications in areas such as energy production and analytical chemistry. This review emphasizes the major classes of modified electrodes with mediators that are being explored for improving analytical methodology. Chemically modified electrodes (CMEs) have been widely used to counter the problems of poor sensitivity and selectivity faced in bare electrodes. We have briefly reviewed the organometallic and organic mediators that have been extensively employed to engineer adapted electrode surfaces for the detection of different compounds. Also, the characteristics of the materials that improve the electrocatalytic activity of the modified surfaces are discussed.

Objective:

Improvement and promotion of pragmatic CMEs have generated a diversity of novel and probable strong detection prospects for electroanalysis. While the capability of handling the chemical nature of the electrode/solution interface accurately and creatively increases , it is predictable that different mediators-based CMEs could be developed with electrocatalytic activity and completely new applications be advanced.

A Novel Electrochemical Sensor Based on Au-rGO Nanocomposite Decorated with Poly(L-cysteine) for Determination of Paracetamol

Background:

Paracetamol is a common antipyretic and analgesic drug, but its excessive intake can accumulate toxic metabolites and cause kidney and liver damage, so it is critical to determine the content of paracetamol for clinical diagnosis and dose use.

Methods:

Au-reduced graphene oxide (Au-rGO) nanocomposite decorated with poly(L-cysteine) on carbon paste electrode was fabricated for the determination of paracetamol. Au-rGO was first coelectrodeposited on the carbon paste electrode surface. Afterwards, L-cysteine was electropolymerized to fabricate the Au-rGO/poly(L-cysteine) modified carbon paste electrode. Scanning electron microscope was used to characterize the morphology of Au-rGO and poly(L-cysteine)/Au-rGO. The electrochemical properties of the sensor were studied by cyclic voltammetry and differential pulse voltammetry.

Results:

After exploring the optimal conditions, the sensor showed a wide linear response for paracetamol detection in the range of 1-200 μM with a detection limit of 0.5 μM (S/N = 3).

Conclusion:

The fabricated sensor demonstrated good sensitivity with rapid detection capacity in real samples.

A signal-on built in-marker electrochemical aptasensor for human prostate-specific antigen based on a hairbrush-like gold nanostructure

A green electrodeposition method was firstly employed for the synthesis of round hairbrush-like gold nanostructure in the presence of cadaverine as a size and shape directing additive. The nanostructure which comprised of arrays of nanospindles was then applied as a transducer to fabricate a signal-on built in-marker electrochemical aptasensor for the detection of human prostate-specific antigen (PSA). The aptasensor detected PSA with a linear concentration range of 0.125 to 128 ng mL-1 and a limit of detection of 50 pg mL-1. The aptasensor was then successfully applied to detect PSA in the blood serum samples of healthy and patient persons.

Gold Electrodes Modified with Calix[4]arene for Electrochemical Determination of Dopamine in the Presence of Selected Neurotransmitters

Here, we present an electrochemical sensor based on gold electrodes modified with calix[4]arene functionalized with carboxypiperidino groups at the upper rim. It has been demonstrated that these groups are involved in a complex formation with dopamine (DA) on the surface of gold electrodes. The supramolecular complex calix[4]arene–DA created on the gold electrode surface has been characterized electrochemically and the measuring conditions have been optimized. The presented sensor displayed a detection limit in the pM range. The DA determination was performed successfully in the presence of ascorbic acid, uric acid and selected neurotransmitters.

Detection of molecular interactions with modified ferrocene self-assembled monolayers

Ferrocene-terminated self-assembled monolayers (Fc-SAMs) are one of the most studied molecular aggregates on metal electrodes. They are easy to fabricate and provide a stable and reproducible system to investigate the effect of the microenvironment on the electron transfer parameters. We propose a novel application for Fc-SAMs, the detection of molecular interactions, based on the modification of the SAM with target-specific receptors. Mixed SAMs were fabricated by coimmobilization on Au electrodes of thiolated alkane chains with three different head groups: hydroxy terminating head group, ferrocene head group, and a functional head group such as biotin. Upon binding, the intrinsic electric charge of the target (e.g., streptavidin) modifies the electrostatic potential at the plane of electron transfer, causing a shift in the formal potential E degrees '. The SAMs were characterized by AC voltammetry. The detection mechanism is confirmed by measurements of formal potential as a function of electrolyte pH.