A mechanothermal approach for the synthesis of Fe3O4 nanoparticles as dopant on mesoporous TiO2 for electrochemical determination of catechol

The subject of water contamination and how it gets defiled to the society and humans is confabulating from the past decades. Phenolic compounds widely exist in the water sources and it is emergent to determine the toxicity in natural and drinking water, because it is hazardous to the humans. Among these compounds, catechol has sought a strong concern because of its rapid occurrence in nature and its potential toxicity to humans. The present work aims to develop an effective electrochemical sensing of catechol using mesoporous structure of Fe₃O₄-TiO₂ decorated on glassy carbon (GC) electrode. The creation of pure TiO₂ using the sol-gel technique was the first step in the synthesis protocol for binary nanocomposite, which was then followed by the loading of Fe₃O₄ nanoparticles on the surface of TiO₂ using the thermal decomposition method. The resultant Fe₃O₄-TiO₂ based nanocomposite exhibited mesoporous structure and the cavities were occupied with highly active magnetite nanoparticles (Fe₃O₄) with high specific surface area (90.63 m²/g). When compared to pure TiO₂, catechol showed a more prominent electrochemical response for Fe₃O₄-TiO₂, with a significant increase in anodic peak current at a lower oxidation potential (0.387 V) with a detection limit of 45 μM. Therefore, the prepared magnetite binary nanocomposite can serve as an efficient electroactive material for sensing of catechol, which could also act as a promising electrocatalyst for various electrocatalytic applications.

An ultra-sensitive laccase/polyaziridine-bismuth selenide nanoplates modified GCE for detection of atenolol in pharmaceuticals and urine samples

The analysis of β-blockers in pharmaceutical, biological and environmental samples has gained much interest due to their wide applications. The aim of this study was to develop an enzyme-based biosensor using hexagonal-shaped low-dimensional Bi₂Se₃ NPs decorated with laccase through polyaziridine (PAZ) modified glassy carbon electrode (Lac/PAZ-Bi₂Se₃ NPs/GCE). Surface properties were examined using SEM, TEM, EDX, XRD, XPS, FTIR, UV-Visible, and zeta potential. Electrochemical studies were performed with cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The enzymatic biosensor exhibited excellent catalytic activity towards the oxidation of ATN at +1.05 V (vs Ag/AgCl). Under the optimum experimental conditions, I_p (µA) was linearly related to the concentrations of ATN in the range of 3 to 130 µM (R² = 0.9972) with an LOD of 0.15 µM and 0.21 µM with and without Lac enzyme. Additionally, the validation of the biosensor was tested to determine ATN on within a day and between-day basis. The biosensor was applied successfully to detect ATN in real samples. The obtained recoveries range from 98.5 % to 99.2 % with an RSD (n = 5) of 0.95 (±0.02). The findings of this study have potential biomedical applications in drug detection employing a promising nano electrode sensor of Lac/PAZ-Bi₂Se₃ NPs/GCE.

Electrochemical determination of atenolol and propranolol using a carbon paste sensor modified with natural ilmenite

In this study, a simple voltammetric method was reported for independent determination of propranolol (PROP) and atenolol (ATN) in pharmaceutical tablets using carbon paste electrode modified with natural Ilmenite (CPE-I). The analytical performance of the modified sensor was evaluated using the square wave voltammetry and cyclic voltammetry for determination of both β(beta) blockers in 0.1 mol L−1 of sulfuric acid solution (H2SO4). The signal obtained with modified carbon paste electrode in 0.1 mol L−1 of H2SO4 showed a good electrocatalytic activity toward the oxidations of PROP and ATN compared with the bare one. The enhanced oxidation peak current response can be attributed to the catalytic effect of the ilmenite nanomaterial incorporated into the carbon paste electrode. Under optimal condition, good linear calibration curves were obtained ranging from 0.20 to 8.9 mmol L−1 for PROP and 2.0 to 9.9 µmol L−1 for ATN, with detection limits of 80 and 0.31 µmol L−1, respectively. The CPE-I sensor had good repeatability and reproducibility (RSD ≤ 3.2%) and high sensitivity for the detection of both ATN and PROP. The proposed sensor was applied for detection of these drugs in pharmaceutical tablets. The obtained results indicate that the voltammetric CPE-I sensor could be an alternative method for the routine quality control of the β blockers in complex matrices.

Rhodium(ii)-catalyzed divergent intramolecular tandem cyclization of N- or O-tethered cyclohexa-2,5-dienones with 1-sulfonyl-1,2,3-triazole: synthesis of cyclopropa[cd]indole and benzofuran derivatives

A novel rhodium(ii)-catalyzed divergent intramolecular tandem cyclization of N- or O-tethered cyclohexa-2,5-dienones and 1-sulfonyl-1,2,3-triazole is disclosed, affording cyclopropa[cd]indole and benzofuran derivatives in moderate to good yields.

Fe2O3 and Gd2O3 nanoparticles loaded in mesoporous silica: insights into influence of NPs concentration and silica dimensionality

Fine Fe₂O₃ and Gd₂O₃ magnetic nanoparticles (NPs) with sizes 7 nm and 10 nm embedded into mesoporous silica have been prepared using a wet-impregnation method. A comparative study of the reactant concentration along with the hosting matrix symmetry on mesostructuring and the magnetic properties of the nanocomposites have been investigated. Reactants with four different concentrations of Fe³⁺ and Gd³⁺ ions and silica matrices with two different kinds of symmetry (hexagonal and cubic) have been utilized for the study. The structural characterization of the samples has been carried out by the N₂ adsorption/desorption method, high-energy X-ray diffraction (HE-XRD), TG/DTA, and high resolution transmission electron microscopy (HRTEM). The magnetic properties of the nanocomposites have been examined by means of SQUID magnetometry. It has been found that a range of different magnetic states (diamagnetic, paramagnetic, ferromagnetic, superparamagnetic) can be induced by the feasible tailoring of the particle concentration, the porous matrix symmetry and the composition. Furthermore, the existence of a “critical concentration limit” for embedding the particles within the body of the matrix has been confirmed. Exceeding the limit results in the expulsion of nanoparticles on the outer surface of the mesoporous matrix. Revelation of the relationships between particle concentration, matrix symmetry and magnetic properties of the particular composite reported in this study may facilitate the design and construction of advanced intelligent nanodevices.

The concentration of nanoparticles inside the pores and the symmetry of the porous matrix significantly affected the magnetic properties.

New insights into the structure-performance relationships of mesoporous materials in analytical science

Mesoporous materials are ideal carriers for guest molecules and they have been widely used in analytical science. The unique mesoporous structure provides special properties including large specific surface area, tunable pore size, and excellent pore connectivity. The structural properties of mesoporous materials have been largely made use of to improve the performance of analytical methods. For instance, the large specific surface area of mesoporous materials can provide abundant active sites and increase the probability of contact between analytes and active sites to produce stronger signals, thus leading to the improvement of detection sensitivity. The connections between analytical performances and the structural properties of mesoporous materials have not been discussed previously. Understanding the "structure-performance relationship" is highly important for the development of analytical methods with excellent performance based on mesoporous materials. In this review, we discuss the structural properties of mesoporous materials that can be optimized to improve the analytical performance. The discussion is divided into five sections according to the analytical performances: (i) selectivity-related structural properties, (ii) sensitivity-related structural properties, (iii) response time-related structural properties, (iv) stability-related structural properties, and (v) recovery time-related structural properties.

Gelatin-functionalized mesoporous silica nanoparticles with sustained release properties for intracameral pharmacotherapy of glaucoma

Herein, pilocarpine-loaded gelatin-covered mesoporous silica nanoparticles (denoted as p/GM) were intracamerally administrated into the anterior chamber for the reduction of intraocular pressure (IOP).

Nano-materials for use in sensing of salmonella infections: Recent advances

Salmonella infectious diseases spreading every day through food have become a life-threatening problem for millions of people and growing menace to society. Health expert's estimate that the yearly cost of all the food borne diseases is approximately $5-6 billion. Traditional methodologies for salmonella analysis provide high reliability and very low limits of detection. Among them immunoassays and Nucleic acid-based assays provide results within 24h, but they are expensive, tedious and time consuming. So, there is an urgent need for development of rapid, robust and cost-effective alternative technologies for real-time monitoring of salmonella. Several biosensors have been designed and commercialized for detection of this pathogen in food and water. In this overview, we have updated the literature concerning novel biosensing methods such as various optical and electrochemical biosensors and newly developed nano- and micro-scaled and aptamers based biosensors for detection of salmonella pathogen. Furthermore, attention has been focused on the principal concepts, applications, and examples that have been achieved up to diagnose salmonella. In addition, commercial biosensors and foreseeable future trends for onsite detecting salmonella have been summarized.

Biomedical Probes Based on Inorganic Nanoparticles for Electrochemical and Optical Spectroscopy Applications

Inorganic nanoparticles usually provide novel and unique physical properties as their size approaches nanometer scale dimensions. The unique physical and optical properties of nanoparticles may lead to applications in a variety of areas, including biomedical detection. Therefore, current research is now increasingly focused on the use of the high surface-to-volume ratios of nanoparticles to fabricate superb chemical- or biosensors for various detection applications. This article highlights various kinds of inorganic nanoparticles, including metal nanoparticles, magnetic nanoparticles, nanocomposites, and semiconductor nanoparticles that can be perceived as useful materials for biomedical probes and points to the outstanding results arising from their use in such probes. The progress in the use of inorganic nanoparticle-based electrochemical, colorimetric and spectrophotometric detection in recent applications, especially bioanalysis, and the main functions of inorganic nanoparticles in detection are reviewed. The article begins with a conceptual discussion of nanoparticles according to types, followed by numerous applications to analytes including biomolecules, disease markers, and pharmaceutical substances. Most of the references cited herein, dating from 2010 to 2015, generally mention one or more of the following characteristics: a low detection limit, good signal amplification and simultaneous detection capabilities.