Electrochemical Determination of the Serotonin Reuptake Inhibitor, Dapoxetine, Using Cesium-Gold Nanoparticles

Electrochemical aptasensor based on the target-induced strand displacement strategy-driven for T-2 toxin detection

Herein, an aptasensor based on target-induced strand displacement (TISD) strategy was developed for sensitive detection of T-2 toxin. Gold nanoparticles@ aminated manganese dioxide (AuNPs@NH₂-MnO₂) exhibited excellent electrical conductivity and provided more binding sites for aptamer (Apt). Besides, polyethyleneimine-reduced graphene oxide/gold‑platinum core-shell nanorods composites (PEI-rGO/Pt@Au NRs) were used to be carriers for signaling tags, as their sufficiently large specific surface area improved the loading capacity for signal molecules. In the presence of T-2, the Apt sequence was more inclined to form an Apt-T-2 complex, and the cDNA was displaced from the Apt-cDNA duplex, while the signal tag was released, resulting in a weakened MB signal, differential pulse voltammetry (DPV) was used to record the signal change. Under optimal conditions, the signal response of the constructed electrochemical aptasensor exhibited a good linear relationship with the concentration of T-2. The detection limit was 8.74 × 10^-7 ng mL^-1over a wide range of concentration from 5 × 10^-6 ng mL^-1 to 5 ng mL^-1. Furthermore, the proposed aptasensor had excellent specificity, good stability and can be well applied to the detection of real samples. It provided a new avenue for the research and development of sensitive aptasensors in food detection and analysis.

Application of a Conducting Poly-Methionine/Gold Nanoparticles-Modified Sensor for the Electrochemical Detection of Paroxetine

This work demonstrates a facile electropolymerization of a dl-methionine (dl-met) conducting polymeric film on a gold nanoparticle (AuNPs)-modified glassy carbon electrode (GCE). The resulting sensor was successfully applied for the sensitive detection of paroxetine·HCl (PRX), a selective serotonin (5-HT) reuptake inhibitor (SSRIs), in its pharmaceutical formulations. The sensor was characterized morphologically using scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM) and electrochemical techniques such as differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The proposed sensor, poly (dl-met)/AuNPs-GCE, exhibited a linear response range from 5 × 10⁻¹¹ to 5 × 10⁻⁸ M and from 5 × 10⁻⁸ to 1 × 10⁻⁴ M using DPV with lowest limit of detection (LOD = 1 × 10⁻¹¹ M) based on (S/N = 3). The poly (dl-met)/AuNPs-GCE sensor was successfully applied for PRX determination in three different pharmaceutical formulations with percent recoveries between 96.29% and 103.40% ± SD (±0.02 and ±0.58, respectively).

Investigation of the association complex formed between dapoxetine and erythrosine-B for facile dapoxetine assay in pharmaceutical formulation using resonance Rayleigh scattering and spectrofluorimetric techniques

Premature ejaculation is a male sexual problem that is marked by rapid ejaculation and quick attainment of orgasm. Dapoxetine belongs to the antidepressant category and modulates its action by preventing the reuptake of serotonin by neurons. Dapoxetine is marketed as an off-label therapy for premature ejaculation. Here, two facile, sensitive, and green compatible approaches were established for dapoxetine assay. The approaches chemically rely on association complex formed between erythrosine-B and dapoxetine in an acidic buffered medium. The quenching effect of the formed complex on the native erythrosine fluorescence at emission 553.5 nm is simply the main idea of spectrofluorimetric assay, while resonance Rayleigh scattering methodology uses augmentation of resonance Rayleigh scattering spectrum at 345 nm by the added dapoxetine. The current approaches exhibit linearity between response and dapoxetine concentration over 0.2-2.5 μg/ml and 0.3-3.0 μg/ml for spectrofluorimetric and resonance Rayleigh scattering (RRS) methods, respectively. All variables affecting methods and complex formation were studied and precisely optimized. The criteria of validation were performed by the directives provided by International Conference on Harmonization's (ICH) Guidelines and limits of detection were 0.06 and 0.05 μg/ml for spectrofluorimetric and RRS techniques, respectively. Finally, the approaches were applied with acceptable results for pharmaceutical formulation analysis.

One-pot micellar augmented native fluorescence for facile fluorimetric assay of dapoxetine hydrochloride in biological plasma and tablets

One of the medical problems is premature ejaculation which characterized by quick ejaculation and reaching orgasm rapidly. Dapoxetine was accepted as off-label antidepressant used in the treatment of premature ejaculation, so hereby we provide an innovative, non-extractive, environmentally safe protocol for the assay of dapoxetine in biological plasma and tablet. The principle of the assay is simple and only based on native fluorescence which was enhanced by micelle. Parameters influencing the method were optimized and measurements were accomplished at emission wavelength of 338 nm after excitation at 294 nm. The fluorescence-concentration plot was rectilinear over the range of 0.1-4 μg/mL. Directives of ICH guideline were the rules which followed to ensure the validity of the work. Eventually, the procedure was utilized in the dosage form assay and extended to include biological plasma analyses, with good percentage recuperation.

High performance liquid chromatography - Mass spectrometric bioanalytical method for the determination of dapoxetine in human plasma: Application for bioequivalence study

Dapoxetine is an oral medication used for treatment of premature ejaculation (PE) in men aged (18-64 years). In this study, we present a validated, precise and sensitive method for determination of dapoxetine in human plasma by liquid chromatography/ electrospray ionization-tandem mass spectrometry. Dapoxetine and the internal standard (Dapoxetine- d₆) were extracted from plasma via liquid-liquid extraction (LLE). The LC separation was performed utilizing ACE C8 (4.6 X50) mm, 5 µm column. The mobile phase was composed of acetonitrile and buffer (0.01 M Ammonium acetate +0.02% Formic acid solution) (85:15, v/v). The method was linear within the concentration range of 5.0-600 ng/mL for Dapoxetine in human plasma. Short analytical run was achieved with 1.6 min run time. Intra-day and inter-day accuracy was between 97 and 106% with precision (CV, %) of ≤ 5% achieved across all the quality control samples. Dapoxetine was stable in several conditions with recovery rates > 90%. This method was utilized successfully in clinical pharmacokinetic study following oral administration of 60 mg Dapoxetine tablets in 36 healthy male subjects. The result for all 90% confidence intervals were within the preset ranges. The method proved to be highly reproducible and sensitive and thus can be employed in bioequivalence studies and large scale sample analysis of Dapoxetine.

Recent Advances in Electrochemical Sensors and Biosensors for Detecting Bisphenol A

In recent years, several studies have focused on environmental pollutants. Bisphenol A (BPA) is one prominent industrial raw material, and its extensive utilization and release into the environment constitute an environmental hazard. BPA is considered as to be an endocrine disruptor which mimics hormones, and has a direct relationship to the development and growth of animal and human reproductive systems. Moreover, intensive exposure to the compound is related to prostate and breast cancer, infertility, obesity, and diabetes. Hence, accurate and reliable determination techniques are crucial for preventing human exposure to BPA. Experts in the field have published general electrochemical procedures for detecting BPA. The present timely review critically evaluates diverse chemically modified electrodes using various substances that have been reported in numerous studies in the recent decade for use in electrochemical sensors and biosensors to detect BPA. Additionally, the essential contributions of these substances for the design of electrochemical sensors are presented. It has been predicted that chemically modified electrode-based sensing systems will be possible options for the monitoring of detrimental pollutants.

Native and synchronous fluorescence spectroscopy for determination of avanafil in presence of its co-formulated drug (dapoxetine hydrochloride): Application to pharmaceutical product, biological fluid and content uniformity

The native and synchronous fluorescence spectroscopy procedures have been established and validated for the simultaneous determination of a binary mixture of dapoxetine hydrochloride (DAP) and avanafil (AVA). The first procedure is based on measurement of native fluorescence intensity of both drugs at λ_Em 337 nm and 370 nm using λ_Ex 290 nm and 314 nm for DAP and AVA in methanol respectively. The second procedure describes a measurement of synchronous fluorescence intensity of these drugs at 232 nm for DAP, and 267 nm for AVA, using Δλ of 90nm. In the first procedure the fluorescence concentration were 0.1-4.0 μg/mL for DAP and 0.5-16 μg/mL for AVA. For the second procedure fluorescence concentrations were 0.025-1.0 μg/mL and 0.5-16 μg/mL for DAP and AVA respectively, with lower detection limit and quantification limits. The processes were successfully used for the limitation of DAP and AVA in their drug product without pre-separation. Then, the techniques were utilized for the determination of DAP and AVA in biological fluids. There is a good agreement between these results and the results obtained using a reference method.

Smart electrochemical sensing platform for the simultaneous determination of psychotic disorder drugs isopropamide iodide and trifluoperazine hydrochloride

Schematic representation of carboxylation of multiwalled carbon nanotubes.