Dopamine (DA) is a significant neurotransmitter in the central nervous system, coexisting with uric acid (UA) and ascorbic acid (AA). UA and AA are easily oxidizable compounds having potentials close to that of DA for electrochemical analysis, resulting in overlapping voltammetric response. In this work, a novel molecularly imprinted (MI) electrochemical sensor was proposed for selective determination of DA (in the presence of up to 80‐fold excess of UA and AA), relying on gold nanoparticles (Aunano)‐decorated glassy carbon (GC) electrode coated with poly(carbazole (Cz)‐co‐aniline (ANI)) copolymer film incorporating DA as template (DA imprinted‐GC/P(Cz‐co‐ANI)‐Aunano electrode, DA‐MIP‐Aunano electrode). The DA recognizing sensor electrode showed great electroactivity for analyte oxidation in 0.2 mol L−1 pH 7 phosphate buffer. Square wave voltammetry (SWV) was performed within 10−4–10−5 mol L−1 of DA, of which the oxidation peak potential was observed at 0.16 V. The limit of detection (LOD) and limit of quantification (LOQ) were 2.0×10−6 and 6.7×10−6 mol L−1, respectively. Binary and ternary synthetic mixtures of DA‐UA, DA‐AA and DA‐UA‐AA yielded excellent recoveries for DA. Additionally, DA was quantitatively recovered from a real sample of bovine serum spiked with DA, and determined in concentrated dopamine injection solution. The developed SWV method was statistically validated against a literature potentiodynamic method using a caffeic acid modified‐GC electrode.
The
sensitive and selective determination of peroxide-based explosives
(PBEs) in the field/on site is an important analytical challenge.
Most methods claiming to detect PBEs are indirect, actually detecting
their decomposition product, H2O2. Here, we
present an electrochemical sensor for direct detection of organic
peroxide explosives, that is, triacetone triperoxide (TATP) and hexamethylenetriperoxide
diamine (HMTD), using well-dispersed multiwalled carbon nanotubes/polyethyleneimine
(MWCNTs/PEI)-modified glassy carbon (GC) electrode, namely, GC/MWCNTs/PEI
electrode. This is the first use of the conductive polyelectrolyte
PEI as an electrode modifier for pristine PBE sensing. The potential
range, scan rate, solvent selection, and supporting electrolyte concentration
were optimized for PBEs. As a distinct advantage over other similar
methods, our sensor electrode responded to intact TATP solutions in
neutral medium, meaning that TATP did not interact with acids/bases
that would transform it into H2O2. Calibration
curves were linear in the range of 10–200 mg L–1 for TATP and 25–200 mg L–1 for HMTD. Using
differential pulse voltammetry, detection limits of 1.5 mg L–1 TATP and 3.0 mg L–1 HMTD were obtained from direct
electrochemical reduction in 80/20% (v/v) H2O–acetone
solvent medium. Electroactive camouflage materials such as passenger
belongings (e.g., sweetener, detergent, sugar, and paracetamol–caffeine-based
analgesic drugs), common ions, and other explosives were shown not
to interfere with the proposed method. The nonresponsive behavior
of our electrode to H2O2 prevents “false
positives” from other peroxide materials of everyday use. This
electrochemical sensor could also detect other nitro-explosives at
different potentials and was statistically validated against standard
GC–MS and spectrophotometric methods.
Explosive detection technologies play a critical role in maintaining national security, remain an active research field with many devices and analytical/electroanalytical techniques. Analytical chemistry needs for homeland defense against terrorism make it clear that real-time and on-site detection of explosives and chemical warfare agents (CWAs) are in urgent demand. Thus, current detection techniques for explosives have to be improved in terms of sensitivity and selectivity, opening the way to electrochemical devices suitable to obtain the targeted analytical information in a simpler, cheaper and faster way. For the electrochemical determination of energetic substances, a large number of sensor electrodes have been presented in literature using different modification materials, especially displaying higher selectivity with molecularly imprinted polymers (MIPs). MIPs have already been utilized for the detection of hazardous materials due to their mechanical strength, flexibility, long-time storage and low cost. The sensitivity of MIPbased electrosensors can be enhanced by coupling with nanomaterials such as graphene oxide (GOx), carbon nanotubes (CNTs), or nanoparticles (NPs). Specific characteristics of involved nanomaterials, their modification, detection mechanism, and other analytical aspects are discussed in detail. Non-MIP electrosensors are generally functionalized with materials capable of charge transfer, H-bonding or electrostatic interactions with analytes for pre-concentration and electrocatalysis on their surface, whereas nanobio-electrosensors use analyte-selective aptamers having specific sequences of DNA, peptides or proteins to change the potential or current. This review intends to provide a combination of information related to MIPs and nanomaterial-based electrochemical sensors, limited to the most significant and illustrative work recently published.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.