Application of spinel-structured MgFe2O4 nanoparticles for simultaneous electrochemical determination diclofenac and morphine

Advances of Drugs Electroanalysis Based on Direct Electrochemical Redox on Electrodes: A Review

The strong development of mankind is inseparable from the proper use of drugs, and the electroanalytical research of drugs occupies an important position in the field of analytical chemistry. This review mainly elaborates the research progress of drugs electroanalysis based on direct electrochemical redox on various electrodes for the recent decade from 2011 to 2021. At first, we summarize some frequently used electrochemical data processing and electrochemical mechanism research derivation methods in the literature. Then, according to the drug therapeutic and application/usage purposes, the research progress of drugs electrochemical analysis is classified and discussed, where we focus on drugs electrochemical reaction mechanism. At the same time, the comparisons of electrochemical sensing performance of the drugs on various electrodes from recent studies are listed, so that readers can more intuitively compare and understand the electroanalytical sensing performance of each modified electrode for each of the drug. Finally, this review discusses the shortcomings and prospects of the drugs electroanalysis based on direct electrochemical redox research.

Electrochemical Detection of Morphine in Untreated Human Capillary Whole Blood

Disposable single-use electrochemical sensor strips were used for quantitative detection of small concentrations of morphine in untreated capillary whole blood. Single-walled carbon nanotube (SWCNT) networks were fabricated on a polymer substrate to produce flexible, reproducible sensor strips with integrated reference and counter electrodes, compatible with industrial-scale processes. A thin Nafion coating was used on top of the sensors to enable direct electrochemical detection in whole blood. These sensors were shown to detect clinically relevant concentrations of morphine both in buffer and in whole blood samples. Small 38 μL finger-prick blood samples were spiked with 2 μL of morphine solution of several concentrations and measured without precipitation of proteins or any other further pretreatment. A linear range of 0.5-10 μM was achieved in both matrices and a detection limit of 0.48 μM in buffer. In addition, to demonstrate the applicability of the sensor in a point-of-care device, single-determination measurements were done with capillary samples from three subjects. An average recovery of 60% was found, suggesting that the sensor only measures the free, unbound fraction of the drug. An interference study with other opioids and possible interferents showed the selectivity of the sensor. This study clearly indicates that these Nafion/SWCNT sensor strips show great promise as a point-of-care rapid test for morphine in blood.

Ultrasensitive photoelectrochemical aptasensor for diclofenac sodium based on surface-modified TiO2-FeVO4 composite

Herein, a photoelectrochemical (PEC) aptasensing platform was designed by integrating surface oxygen vacancy (OV) defects, Ti³⁺ self-doping, the heterojunction, and resonance energy transfer (RET) effect into one platform for the detection of diclofenac sodium (DCF). Briefly, OV defects were introduced on TiO₂ nanospheres with simultaneous Ti³⁺ self-doping, followed by a well-separated deposition of FeVO₄ nanoparticles on TiO₂ to obtain a Ti³⁺-O-TiO₂/FeVO₄ heterojunction. The surface modification of OVs, Ti³⁺ doping, and deposition of FeVO₄ were confirmed by SEM, XPS, EPR, DRS, and PEC measurements. The surface OVs and doping of Ti³⁺ species created a new donor (defect) energy level under the conduction band of TiO₂, which minimized the bandgap and thereby improved the visible light absorption of TiO₂. Moreover, the capture of photo-excited electrons by surface OVs could hinder the electron-hole recombination. Due to the intimate surface contact and perfect energy matching between TiO₂ and FeVO₄, the formation of heterojunction decreased the bandgap and facilitated the electron-hole separation of TiO₂. All these above events contributed to the enhancement of the PEC signals, which were then quenched by the RET effect between Ti³⁺-O-TiO₂/FeVO₄ and Au nanoparticle (AuNP)-labeled cDNA that had been attached to its complementary DCF aptamer on Ti³⁺-O-TiO₂/FeVO₄|ITO. The addition of target-DCF detached AuNP-labeled cDNA from the electrode to recover the photocurrent, resulting in a "signal-on" PEC aptasensor that exhibited a 0.1-500-nM linear range and a detection limit of 0.069 nM for DCF, attributed to the excellent amplification of the proposed aptasensing platform.

Determination of morphine and its metabolites in the biological samples: an updated review

Morphine (MO) as an opioid analgesic is used for the treatment of moderate-to-severe pains, particularly cancer-related pains. Pharmacologic studies on MO are complicated due to drugs binding to the protein or metabolization to active metabolites, and even inter-individual variability. This necessitates the selection of a reliable analytical method for monitoring MO and the concentrations of its metabolites in the biological samples for the pharmacokinetic or pharmacodynamic investigations. Therefore, this study was conducted to review all the analytical research carried out on MO and its metabolites in the biological samples during 2007-2019 as an update to the study by Bosch et al. (2007).

Voltammetric Pathways for the Analysis of Ophthalmic Drugs

Background:

This review investigates the ophthalmic drugs that have been studied with voltammetry in the web of science database in the last 10 years.

Introduction:

Ophthalmic drugs are used in the diagnosis, evaluation and treatment of various ophthalmological diseases and conditions. A significant literature has emerged in recent years that investigates determination of these active compounds via electroanalytical methods, particularly voltammetry. Low cost, rapid determination, high availability, efficient sensitivity and simple application make voltammetry one of the most used methods for determining various kinds of drugs including ophthalmic ones.

Methods:

In this particular review, we searched the literature via the web of science database for ophthalmic drugs which are investigated with voltammetric techniques using the keywords of voltammetry, electrochemistry, determination and electroanalytical methods.

Results:

We found 33 types of pharmaceuticals in nearly 140 articles. We grouped them clinically into seven major groups as antibiotics, antivirals, non-steroidal anti-inflammatory drugs, anti-glaucomatous drugs, steroidal drugs, local anesthetics and miscellaneous. Voltammetric techniques, electrodes, optimum pHs, peak potentials, limit of detection values, limit of quantification values, linearity ranges, sample type and interference effects were compared.

Conclusion:

Ophthalmic drugs are widely used in the clinic and it is important to determine trace amounts of these species analytically. Voltammetry is a preferred method for its ease of use, high sensitivity, low cost, and high availability for the determination of ophthalmic drugs as well as many other medical drugs. The low limits of detection values indicate that voltammetry is quite sufficient for determining ophthalmic drugs in many media such as human serum, urine and ophthalmic eye drops.

Morphology-tunable polydopamine nanoparticles and their application in Fe3+ detection

In this work, we discovered the morphology transformation property of polydopamine (PDA) nanomaterials, the addition of Fe³⁺ initiated the dramatic morphology transformation of PDA dots from aggregated plate-like to uniform willow-leaf-like morphology. Further study revealed that this fascinating morphology transformation process could be attributed to the oxidative nature and coordination characteristic of Fe³⁺. This is the first report on the morphology transformation ability of PDA, and a probable self-assembled mechanism was proposed to explain this issue. Besides, we noticed that morphological and fluorescent properties of PDA dots were closely related, thus a fluorescent Fe³⁺ detection method was presented based on the morphology-tunable PDA dots. With the proposed method, selective Fe³⁺ detection was achieved with a wide linear dynamic range of 10μM to 1mM. Furthermore, since the morphology tuning behavior of PDA dots was easy to operate, we anticipate this ability will find significant utility in sensing, drug delivery, and tissue engineering.