Determination of morphine at gold nanoparticles/Nafion® carbon paste modified sensor electrode

Innovative voltammetric techniques for bumadizone analysis in pharmaceutical and biological samples: emphasizing green, white, and blue analytical approaches

There are no documented electroanalytical methods for quantifying the anti-inflammatory drug bumadizone (BUM) in pharmaceutical or biological matrices. So, a new voltammetric method was developed to determine BUM at nano concentrations in pharmaceutical forms, in the presence of its alkaline degradant, and in biological fluids. Five electrodes were tested, including three nano-reduced graphene oxide (nRGO) electrodes (5%, 15%, and 20%), a carbon paste electrode (CPE), and a 10% nRGO-modified CPE. The 10% nRGO-modified electrode showed the best performance, offering high selectivity and low detection limits, with good linearity in the concentration range of 0.9 × 102 to 15 × 102 ng mL-1. Differential pulse voltammetry successfully applied this electrode for BUM determination in various samples, achieving excellent recovery without preliminary separation. The method was validated according to ICH guidelines and compared favorably to the reference method. Its environmental impact was assessed using AGREE and Eco-scale metrics in addition to the RGB algorithm, showing superior greenness and whiteness profiles due to safer solvents and lower energy consumption, along with high practical effectiveness using the BAGI metric.

How new nanotechnologies are changing the opioid analysis scenery? A comparison with classical analytical methods

Opioids such as heroin, fentanyl, raw opium, and morphine have become a serious threat to the world population in the recent past, due to their increasing use and abuse. The detection of these drugs in biological samples is usually carried out by spectroscopic and/or chromatographic techniques, but the need for quick, sensitive, selective, and low-cost new analytical tools has pushed the development of new methods based on selective nanosensors, able to meet these requirements. Modern sensors, which utilize "next-generation" technologies like nanotechnology, have revolutionized drug detection methods, due to easiness of use, their low cost, and their high sensitivity and reliability, allowing the detection of opioids at trace levels in raw, pharmaceutical, and biological samples (e.g. blood, urine, saliva, and other biological fluids). The peculiar characteristics of these sensors not only have allowed on-site analyses (in the field, at the crime scene, etc.) but also they are nowadays replacing the gold standard analytical methods in the laboratory, even if a proper method validation is still required. This paper reviews advances in the field of nanotechnology and nanosensors for the detection of commonly abused opioids both prescribed (i.e. codeine and morphine) and illegal narcotics (i.e. heroin and fentanyl analogues).

Optimization and analytical behavior of a morphine electrochemical sensor in environmental and biological samples based on graphite rod electrode using graphene/Co3O4 nanocomposite

In this research, a new sensor based on graphene/Co₃O₄ (Gr/Co₃O₄) nanocomposite was employed for electrochemically determination of morphine (MOR). The modifier was synthesized with a simple hydrothermal technique and well characterized using X-ray difraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) tools. The modified graphite rod electrode (GRE) was revealed a high electrochemical catalytic activity for the MOR oxidation and employed for the electroanalysis of trace MOR concentration by means of differential pulse voltammetry (DPV) technique. At the optimum experimental factors, the resulting sensor offered a good response for MOR in the concentration range of 0.5-100.0 μM with a detection limit of 80 nM. In addition, the modified electrode demonstrated an acceptable selectivity, stability and reproducibility. This assay was also provided a valid platform for the detection of MOR in environmental and biological samples with acceptable recoveries and RSD in the range of 97.2-102.8% and 1.7-3.4%, respectively. Taking to the simplicity, low cost and short analysis time, this approach is suggested for clinical, environmental and forensic testing of MOR.

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.

Application of MnO2 Nanorod–Ionic Liquid Modified Carbon Paste Electrode for the Voltammetric Determination of Sulfanilamide

The current work introduced a convenient single-phase hydrothermal protocol to fabricate MnO₂ nanorods (MnO₂ NRs). Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDX) and field-emission scanning electron microscopy (FE-SEM) were used to determine the characteristics of MnO₂ NR. Then, ionic liquid (IL) and MnO₂ NRs were utilized to modify a carbon paste electrode (CPE) surface (MnO₂NR-IL/CPE) to voltammetrically sense the sulfanilamide (SAA). An enhanced voltammetric sensitivity was found for the as-developed modified electrode toward SAA when compared with a bare electrode. The optimization experiments were designed to achieve the best analytical behavior of the SAA sensor. Differential pulse voltammetry (DPV) in the optimized circumstances portrayed a linear dependence on various SAA levels (between 0.07 and 100.0 μM), possessing a narrow detection limit (0.01 μM). The ability of the modified electrode to be used in sensor applications was verified in the determination of SAA present in the actual urine and water specimens, with impressive recovery outcomes.

Mechanism of atmospheric pressure chemical ionization of morphine, codeine, and thebaine in corona discharge-ion mobility spectrometry: Protonation, ammonium attachment, and carbocation formation

Atmospheric pressure chemical ionizations (APCIs) of morphine, codeine, and thebaine were studied in a corona discharge ion source using ion mobility spectrometry (IMS) at temperature range of 100°C-200°C. Density functional theory (DFT) at the B3LYP/6-311++G(d,p) and M062X/6-311++G(d,p) levels of theory were used to interpret the experimental data. It was found that in the presence of H₃ O⁺ as reactant ion (RI), ionization of morphine and codeine proceeds via both the protonation and carbocation formation, whereas thebaine participates only in protonation. Carbocation formation (fragmentation) was diminished with decrease in the temperature. At lower temperatures, proton-bound dimers of the compounds were also formed. Ammonia was used as a dopant to produce NH₄ ⁺ as an alternative RI. In the presence of NH₄ ⁺ , proton transfer from ammonium ion to morphine, codeine, and thebaine was the dominant mechanism of ionization. However, small amount of ammonium attachment was also observed. The theoretical calculations showed that nitrogen atom of the molecules is the most favorable proton acceptor site while the oxygen atoms participate in ammonium attachment. Furthermore, formation of the carbocations is because of the water elimination from the protonated forms of morphine and codeine.

Detection of morphine in urine based on a surface plasmon resonance imaging immunoassay

Based on the surface plasmon resonance imaging (SPRi) technique, a new detection method for morphine in urine samples was developed. Sample labelling was not required, and qualitative and quantitative analysis could be completed in 20 minutes. According to an indirect competitive immunoassay, the mixture of morphine at different concentrations and morphine antibody at a certain concentration as the mobile phase was reacted with morphine BSA fixed on a chip surface in a competitive way. A calibration curve was obtained by correlating the signals generated from SPRi with the concentrations of morphine. By the addition of morphine to a blank urine sample, this method was confirmed to be feasible for the detection of morphine in actual urine. The limit of detection was as low as 9.59 ng mL-1. This method is fast and sensitive and can be applied in many fields.

Novel Design of a Layered Electrochemical Dopamine Sensor in Real Samples Based on Gold Nanoparticles/β-Cyclodextrin/Nafion-Modified Gold Electrode

Change in the level of dopamine (DA) concentration in the human body causes critical diseases such as schizophrenia and Parkinson's disease. Therefore, the determination of DA concentration and monitoring its level in human body fluids is of great importance. An electrochemical sensor based on modification of the gold electrode surface with Nafion (NF), β-cyclodextrin (CD), and gold nanoparticles (AuNPs) was fabricated for the determination of DA in biological fluids. Combined impact of all the modifiers enhances the catalytic activity of the sensor. Gold nanoparticles increase the surface area of the sensor and enhance the electron transfer rate. CD plays a main role in enhancing the accumulation of protonated DA and forming stable complexes via electrostatic interactions and hydrogen bond formation. In addition, extra preconcentration of positively charged DA is achieved through ionic selectivity of NF. High electrocatalytic activity was achieved using the modified sensor for determination of DA in real urine samples in a wide concentration range, 0.05-280 μM with a low detection limit of 0.6 nM in the small linear dynamic range, 0.05-20 μM. Furthermore, common overlapped oxidation peaks of DA in presence of biologically interfering compounds at the gold electrode were resolved by using the modified sensor. Excellent recovery results were obtained using the proposed method for determination of DA in real urine samples.

Simultaneous Detection of Morphine and Codeine in the Presence of Ascorbic Acid and Uric Acid and in Human Plasma at Nafion Single-Walled Carbon Nanotube Thin-Film Electrode

In clinical settings, the dosing and differential diagnosis of the poisoning of morphine (MO) and codeine (CO) is challenging due to interindividual variations in metabolism. However, direct electrochemical detection of these analytes from biological matrices is inherently challenging due to interference from large concentrations of anions, such as ascorbic acid (AA) and uric acid (UA), as well as fouling of the electrode by proteins. In this work, a disposable Nafion-coated single-walled carbon nanotube network (SWCNT) electrode was developed. We show facile electron transfer and efficient charge separation between the interfering anions and positively charged MO and CO, as well as significantly reduced matrix effect in human plasma. The Nafion coating alters the voltammetric response of MO and CO, enabling simultaneous detection. With this SWCNT/Nafion electrode, two linear ranges of 0.05-1 and 1-10 μM were found for MO and one linear range of 0.1-50 μM for CO. Moreover, the selective and simultaneous detection of MO and CO was achieved in large excess of AA and UA, as well as, for the first time, in unprocessed human plasma. The favorable properties of this electrode enabled measurements in plasma with only mild dilution and without the precipitation of proteins.

Sensitive and simple simultaneous determination of morphine and codeine using a Zn2SnO4nanoparticle/graphene composite modified electrochemical sensor

Simultaneous determination of morphine and codeine using a nanocomposite modified electrochemical sensor.

Differential pulse stripping voltammetric determination of the antipsychotic medication olanzapine at a magnetic nano-composite with a core/shell structure

Fe₃O₄@Ag core/shell MNPs were used for modification of carbon paste electrode and the modified electrode was utilized for electrochemical determination of olanzapine.

Nanomaterial-based electrochemical sensing of neurological drugs and neurotransmitters

Nanomaterial-modified detection systems represent a chief driver towards the adoption of electrochemical methods, since nanomaterials enable functional tunability, ability to self-assemble, and novel electrical, optical and catalytic properties that emerge at this scale. This results in tremendous gains in terms of sensitivity, selectivity and versatility. We review the electrochemical methods and mechanisms that may be applied to the detection of neurological drugs. We focus on understanding how specific nano-sized modifiers may be applied to influence the electron transfer event to result in gains in sensitivity, selectivity and versatility of the detection system. This critical review is structured on the basis of the Anatomical Therapeutic Chemical (ATC) Classification System, specifically ATC Code N (neurotransmitters). Specific sections are dedicated to the widely used electrodes based on the carbon materials, supporting electrolytes, and on electrochemical detection paradigms for neurological drugs and neurotransmitters within the groups referred to as ATC codes N01 to N07. We finally discuss emerging trends and future challenges such as the development of strategies for simultaneous detection of multiple targets with high spatial and temporal resolutions, the integration of microfluidic strategies for selective and localized analyte pre-concentration, the real-time monitoring of neurotransmitter secretions from active cell cultures under electro- and chemotactic cues, aptamer-based biosensors, and the miniaturization of the sensing system for detection in small sample volumes and for enabling cost savings due to manufacturing scale-up. The Electronic Supporting Material (ESM) includes review articles dealing with the review topic in last 40 years, as well as key properties of the analytes, viz., pKa values, half-life of drugs and their electrochemical mechanisms. The ESM also defines analytical figures of merit of the drugs and neurotransmitters. The article contains 198 references in the main manuscript and 207 references in the Electronic Supporting Material. Figureᅟ

A new platform for sensing urinary morphine based on carrier assisted electromembrane extraction followed by adsorptive stripping voltammetric detection on screen-printed electrode

Electromembrane extraction (EME) coupled with electrochemical detection on screen-printed carbon electrode has been developed for the quantification of morphine in urine samples. Charged morphine molecules were extracted from an aqueous sample by applying an electrical potential through a thin supported liquid membrane (SLM) into an acidic aqueous acceptor solution (20 µL) placed inside the lumen of a hollow fiber. Then, the acceptor solution was mixed with 20 µL of NaOH solution (0.1 M) and analyzed using screen printed electrochemical strip. Differential pulse voltammetry (DPV) peak current at 0.18 V was selected as the signal and the influences of experimental parameters were investigated and optimized using Box-behnken design and also one-variable-at-a-time methodology as follows: adsorptive accumulation time, 40 s; SLM, 2-nitrophenyl octyl ether+10% tris-(2-ethylhexyl) phosphate+10% di-(2-ethylhexyl) phosphate; pH of the sample solution, 6.0; pH of the acceptor solution, 1.0; EME time, 24 min; EME potential, 90 V and stirring rate, 1000 rpm. The calibration curve which was plotted by the variation of DPV currents as a function of morphine concentration was linear within the range of 0.005-2.0 µg mL(-1). The limit of detection and the limit of quantification were 0.0015 (S/N=3) and 0.005 µg mL(-1), respectively. Finally, the proposed method was able to determine morphine simply and effectively at concentration levels encountered in toxicology and doping.