Highly electroactive Ce-ZnO/rGO nanocomposite: Ultra-sensitive electrochemical sensing platform for carbamazepine determination

A ratiometric electrochemical sensor for antiepileptic drug of carbamazepine based on electroactive Ni2+-terephthalic acid MOF

Carbamazepine (CBZ), an anticonvulsant and mood stabilizer used extensively for epilepsy, requires a reliable and sensitive monitoring assay for assessing and optimizing the dosage administered to epileptic patients. In this work, spherical nickel-based metal-organic framework materials (Ni-MOFs) consisting of nanosheets were synthesized and cast on glassy carbon electrode (GCE) to prepare a novel ratiometric CBZ electrochemical sensor. The electrochemical test results showed that the Ni-MOF-based sensor had a pair of reversible redox peaks at +0.54 V and +0.39 V, respectively, originating from the Ni3+/Ni2+ pair. Meanwhile, CBZ presented an intense irreversible oxidation peak at +1.22 V on the sensor, and its peak current intensity was significantly higher than that on bare GCE and Nafion/GCE. This enhancement can be ascribed to the synergistic effects of the extensive electroactive surface area and the superior electron transfer kinetics of the Ni-MOF, as evidenced by comprehensive physical and electrochemical characterizations. Further, ratiometric sensing detection of CBZ can be achieved by measuring the ratio (R) of oxidation peak currents between CBZ and Ni-MOF, using the Ni-MOF's oxidation peak as the internal reference signal. Under the optimal experimental conditions, the sensor can detect CBZ in the concentration range from 20 to 300 μM with the detection limit as low as 1.03 μM. The recoveries of 94.2-103.3 % were obtained when the sensor was used for the determination of CBZ in serum samples, which demonstrated that the sensor has potential applications in the monitoring of CBZ residues in biological samples.

Electrochemical Carbamazepine Aptasensor for Therapeutic Drug Monitoring at the Point of Care

Monitoring the anti-epileptic drug carbamazepine (CBZ) is crucial for proper dosing, optimizing a patient's clinical outcome, and managing their medication regimen. Due to its narrow therapeutic window and concentration-related toxicity, CBZ is prescribed and monitored in a highly personalized manner. We report an electrochemical conformation-changing aptasensor with two assay formats: a 30 min assay for routine monitoring and a 5 min assay for rapid emergency testing. To enable "sample-to-answer" testing, a de novo CBZ aptamer (K _d < 12 nM) with conformational switching due to a G-quadruplex motif was labeled with methylene blue and immobilized on a gold electrode. The electrode fabrication and detection conditions were optimized using electrochemical techniques and visualized by atomic force microscopy (AFM). The aptasensor performance, including reproducibility, stability, and interference, was characterized using electrochemical impedance spectroscopy and voltammetry techniques. The aptasensor exhibited a wide dynamic range in buffer (10 nM to 100 μM) with limits of detection of 1.25 and 1.82 nM for the 5 and 30 min assays, respectively. The clinical applicability is demonstrated by detecting CBZ in finger prick blood samples (<50 μL). The proposed assays provide a promising method to enable point-of-care monitoring for timely personalized CBZ dosing.

A Molecular Imprinted PEDOT CMOS Chip-Based Biosensor for Carbamazepine Detection

A miniaturized biosensor for carbamazepine (CBZ) detection and quantification was designed, implemented and fabricated. The 1×1 mm² CMOS chip was packaged and coupled with a 3-electrode electrochemical cell. A complete characterization of the sensor was conducted via two steps: 1) Molecular imprinting of PEDOT polymer sites by cyclic voltammetry (CV) on glassy carbon electrode (GCE) surfaces; and 2) Quantification of CBZ solutions through both CV, and a current peak detection circuitry. The proposed biosensor offered high-selectivity and high-sensitivity to CBZ molecules. Scanning electron microscopy (SEM) was utilized to validate the synthesis of the PEDOT chains. CBZ removal from the imprinted polymer was conducted through soaking the modified GCEs in acetonitrile (ACN). Extraction was then confirmed by ultraviolet-visible (UV-vis) spectroscopy and CV analyzing data from pre- and post-template extraction. Furthermore, in order to characterize the electrodes' response to CBZ levels in phosphate buffered solution (PBS) with [Fe(CN)₆]^3-/4- as a redox pair/mediator, CV and peak detection was conducted resulting in redox peak currents vs. CBZ concentration graphs. The limits of detection (LOD) and quantification (LOQ) were calculated to be 2.04 and 6.2 μg/mL respectively. Finally, selectivity towards CBZ was validated by studying the effect of valproic acid (VPA) and phenytoin (PHT) on the biosensor's performance. The proposed biosensor is highly sensitive and selective to CBZ molecules, simple to construct and easy to operate.

Synthesis and electrochemical properties of environmental free l-glutathione grafted graphene oxide/ZnO nanocomposite for highly selective piroxicam sensing

A simple and reliable strategy was proposed to engineer the glutathione grafted graphene oxide/ZnO nanocomposite (glutathione-GO/ZnO) as electrode material for the high-performance piroxicam sensor. The prepared glutathione-GO/ZnO nanocomposite was well characterized by X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The novel nanocomposite modified electrode showed the highest electrocatalytic activity towards piroxicam (oxidation potential is 0.52 V). Under controlled experimental parameters, the proposed sensor exhibited good linear responses to piroxicam concentrations ranging from 0.1 to 500 μM. The detection limit and sensitivity were calculated as 1.8 nM and 0.2 μA/μM·cm2, respectively. Moreover, it offered excellent selectivity, reproducibility, and long-term stability and can effectively ignore the interfering candidates commonly existing in the pharmaceutical tablets and human fluids even at a higher concentration. Finally, the reported sensor was successfully employed to the direct determination of piroxicam in practical samples.

Carbon based nanomaterials for the detection of narrow therapeutic index pharmaceuticals

Precise detection of important pharmaceuticals with narrow therapeutic index (NTI) is very critical as there is a small window between their effective dose and the doses at which the adverse reactions are very likely to appear. Regarding the fact that various pharmacokinetics will be plausible while considering pharmacogenetic factors and also differences between generic and brand name drugs, accurate detection of NTI will be more important. Current routine analytical techniques suffer from many drawbacks while using novel biosensors can bring up many advantages including fast detection, accuracy, low cost with simple and repeatable measurements. Recently the well-known carbon Nano-allotropes including carbon nanotubes and graphenes have been widely used for development of different Nano-biosensors for a diverse list of analytes because of their great physiochemical features such as high tensile strength, ultra-light weight, unique electronic construction, high thermo-chemical stability, and an appropriate capacity for electron transfer. Because of these exceptional properties, scientists have developed an immense interest in these nanomaterials. In this case, there are important reports to show the effective Nano-carbon based biosensors in the detection of NTI drugs and the present review will critically summarize the available data in this field.

A simple strategy for the synthesis of flower-like textures of Au-ZnO anchored carbon nanocomposite towards the high-performance electrochemical sensing of sunset yellow

Consumption of sunset yellow (SY) above a certain concentration through food products may leads to adverse health issues. Therefore, it is imperative to develop technologies for rapid and selective detection of SY. Herein, a flower-like reduced graphene oxide (rGO)-graphitic carbon nitride (g-CN)/ZnO-Au nanoparticle (NPs) has been prepared and utilized for the specific detection of SY. The fabricated rGO-g-CN/ZnO-AuNPs composite was characterized and investigated by XRD, FTIR, SEM, TEM, XPS, EIS, and voltammetry techniques. Characterization techniques elucidated the deposition of ZnO-AuNPs on to the rGO-g-CN and successful fabrication of rGO-g-CN/ZnO-AuNPs composite. rGO-g-CN/ZnO-AuNPs composite possesses excellent catalytic activity for the oxidation of SY. Developed rGO-g-CN/ZnO-AuNPs sensor exhibits LOD of 1.34 nM for SY concentrations ranging from 5 to 85 nM. Noteworthily, the sensor has been successfully employed for the detection and recovery of SY in real-time samples. Fabricated composite opens up new avenues to develop electrochemical sensor for food safety.

3D cloves bud like Gd doped ZnO strewn rGO hybrid for highly selective determination of l-dopa in the presence of carbidopa and ascorbic acid

An electrochemical sensor using three dimensional (3D) cloves bud like gadolinium doped ZnO nanoflowers strewn reduced graphene oxide (GZO@rGO) modified glassy carbon electrode was proposed for the sensitive and selective detection of l-dopa. The GZO@rGO nanocomposite was synthesized by hydrothermal method and characterized by a variety of analytical and spectroscopy techniques, viz. Field Emission Scanning Electron Microscopy, X-Ray Diffraction, Fourier Transformed Infrared Spectrum and X-ray photoelectron spectroscopy. The electrochemical characterization was evaluated by Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and Differential Pulse Voltammetry (DPV). The 3D cloves bud like GZO@rGO hybrid displayed the highest electro-catalytic behaviour for the selective l-dopa detection. Under optimum conditions, the oxidation current response of l-dopa is directly proportional to its concentration ranging from 10 to 100 nM. The sensitivity and limit of detection was calculated as 0.1 μA nM^-1 cm^-2 and 0.82 nM respectively. Moreover, the proposed electrode offers excellent selectivity, because it can efficiently evade the intervention of carbidopa and ascorbic acid even in the higher concentration. Thus, the reported sensor exhibits accurate determination of l-dopa (in the presence of carbidopa & ascorbic acid) and possesses an excellent real-time application with Mucuna prurita, pharmaceutical and human urine samples.

Preparation and evaluation of a porous molecularly imprinted polymer for selective recognition of the antiepileptic drug carbamazepine

A novel and porous molecularly imprinted polymer (PMIP) was synthesized and used as a solid-phase extraction adsorbent for preconcentration of carbamazepine (CBZ) prior to its quantitation by high-performance liquid chromatography (HPLC) in various sample forms (e.g., drinking water, river water, hospital wastewater, and pharmaceuticals). PMIP-CBZ was applied to a polymerization process in which polystyrene spheres were coated with a silica layer. Removal of polystyrene spheres and formation of porous silica facilitated the recovery of CBZ (99.4%) during the extraction process. Site accessibility to the surface of PMIP-CBZ increased the density of high-recognition sites. PMIP-CBZ was characterized by Fourier-transform infrared spectroscopy and scanning electron microscopy. The key variables influencing the extraction efficiency of PMIP (e.g., adsorbent loading, eluent type, eluent volume, reusability of the adsorbent, and cross-reactivity) were optimized. The optimized protocol was successfully employed to quantify CBZ with limit of detection and limit of quantification as 0.082 and 0.270 ng/mL, respectively (linear detection range: 0.5-250 ng/mL and a relative standard deviation:  < 5%). Use of the PMIP adsorbent resulted in a sensitive and stable method for efficiently quantitation of CBZ from various real sample matrices.