Flow Injection Potentiometric Assay of Hexoprenaline in Its Pure State, Pharmaceutical Preparations, and Biological Samples

Different hexoprenaline (Hx2SO4) conventional and coated wire electrodes were constructed and evaluated. Membranes were based on hexoprenalinium phosphotungstate (Hx-PTA) and hexporenalinium phosphomolybdate (Hx-PMA). The electrodes were fully characterized in terms of their composition, response time, life span, pH, and temperature and then were applied to the potentiometric determination of the hexoprenalinium ion in its pure state, pharmaceutical preparations, and biological samples, urine and plasma, under batch and flow injection conditions. The selectivity of the electrodes towards many inorganic cations, sugars, amino acids, and some other brochodilatures of close chemical composition was also tested

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)

Synthesis and Characterization of Orange Peel Modified Hydrogels as Efficient Adsorbents for Methylene Blue (MB)

In recent years, due to the developments in the textile industry, water contaminated with synthetic dyes such as methylene blue (MB) has become an environmental threat based on the possible impacts in terms of chemical and biochemical demand, which leads to disturbance in aquatic plants photosynthesis, besides their possible toxicity and carcinogenicity for humans. In this work, an adsorbent hydrogel is prepared via free radical polymerization comprising acrylic acid (PAA) as a monomer and orange peel (OP) as a natural modifier rich in OH and COOH present in its cellulose and pectin content. The resulting hydrogels were optimized in terms of the content of OP and the number of cross-linkers and characterized morphologically using Scanning electron microscopy. Furthermore, BET analysis was used to follow the variation in the porosity and in terms of the surface area of the modified hydrogel. The adsorption behavior was found to follow pseudo-second-order as a kinetic model, and Langmuir, Freundlich, and Temkin isotherm models. The combination of OP and PAA has sharply enhanced the adsorption percent of the hydrogel to reach 84% at the first 10 min of incubation with an adsorption capacity of more than 1.93 gm/gm. Due to its low value of pHPZc, the desorption of MB was efficiently performed at pH 2 using HCl, and the desorbed OP-PAA were found to be reusable up to ten times without a decrease in their efficiency. Accordingly, OP-PAA hydrogel represents a promising efficient, cost-effective, and environmentally friendly adsorbent for MB as a model cationic dye that can be applied for the treatment of contaminated waters

Application of Molecularly Imprinted Polymers in the Analysis of Waters and Wastewaters

The increase of the global population and shortage of renewable water resources urges the development of possible remedies to improve the quality and reusability of waste and contaminated water supplies. Different water pollutants, such as heavy metals, dyes, pesticides, endocrine disrupting compounds (EDCs), and pharmaceuticals, are produced through continuous technical and industrial developments that are emerging with the increasing population. Molecularly imprinted polymers (MIPs) represent a class of synthetic receptors that can be produced from different types of polymerization reactions between a target template and functional monomer(s), having functional groups specifically interacting with the template; such interactions can be tailored according to the purpose of designing the polymer and based on the nature of the target compounds. The removal of the template using suitable knocking out agents renders a recognition cavity that can specifically rebind to the target template which is the main mechanism of the applicability of MIPs in electrochemical sensors and as solid phase extraction sorbents. MIPs have unique properties in terms of stability, selectivity, and resistance to acids and bases besides being of low cost and simple to prepare; thus, they are excellent materials to be used for water analysis. The current review represents the different applications of MIPs in the past five years for the detection of different classes of water and wastewater contaminants and possible approaches for future applications

Robust and Optimal Control of Magnetic Microparticles inside Fluidic Channels with Time-Varying Flow Rates

Targeted therapy using magnetic microparticles and nanoparticles has the potential to mitigate the negative side-effects associated with conventional medical treatment. Major technological challenges still need to be addressed in order to translate these particles into in vivo applications. For example, magnetic particles need to be navigated controllably in vessels against flowing streams of body fluid. This paper describes the motion control of paramagnetic microparticles in the flowing streams of fluidic channels with time-varying flow rates (maximum flow is 35 ml.hr−1). This control is designed using a magnetic-based proportional-derivative (PD) control system to compensate for the time-varying flow inside the channels (with width and depth of 2 mm and 1.5 mm, respectively). First, we achieve point-to-point motion control against and along flow rates of 4 ml.hr−1, 6 ml.hr−1, 17 ml.hr−1, and 35 ml.hr−1. The average speeds of single microparticle (with average diameter of 100 μm) against flow rates of 6 ml.hr−1 and 30 ml.hr−1 are calculated to be 45 μm.s−1 and 15 μm.s−1, respectively. Second, we implement PD control with disturbance estimation and compensation. This control decreases the steady-state error by 50%, 70%, 73%, and 78% at flow rates of 4 ml.hr−1, 6 ml.hr−1, 17 ml.hr−1, and 35 ml.hr−1, respectively. Finally, we consider the problem of finding the optimal path (minimal kinetic energy) between two points using calculus of variation, against the mentioned flow rates. Not only do we find that an optimal path between two collinear points with the direction of maximum flow (middle of the fluidic channel) decreases the rise time of the microparticles, but we also decrease the input current that is supplied to the electromagnetic coils by minimizing the kinetic energy of the microparticles, compared to a PD control with disturbance compensation

Fabrication of magnetic molecularly imprinted beaded fibers for rosmarinic acid

The present study describes the fabrication of molecularly imprinted (MI) magnetic beaded fibers using electrospinning. Rosmarinic acid was selected as exemplary yet relevant template during molecular imprinting. A “design of experiments” methodology was used for optimizing the electrospinning process. Four factors, i.e., the concentration of the biodegradable polymer (polycaprolactone), the applied voltage, the flow rate, and the collector distance were varied in a central composite design. The production process was then optimized according to the suitability of the beaded fibers during microrobot fabrication, actuation, and drug release. The optimum average fiber diameter of MI beaded fibers was determined at 857 ± 390 nm with an average number of beads at 0.011 ± 0.002 per µm2 . In vitro release profiles of the optimized MI beaded fibers revealed a lower burst rate and a more sustained release when compared to control fibers. Magnetic control of the MI beaded fibers was successfully tested by following selected waypoints along a star-shaped predefined trajectory. This study innovatively combines molecular imprinting technology with magnetic microrobots enabling targeted drug delivery systems that offer precise motion control via the magnetic response of microrobots along with selective uptake of a drug into the microrobot using MI beaded fibers in future