We present the immunoassay of tau proteins (total tau and phosphorylated tau) in human sera using surface plasmon resonance (SPR) fiber sensors. This assay aimed at harvesting the advantages of using both SPR fiber sensors and a blood-based assay to demonstrate label-free point-of-care-testing (POCT) patient-friendly assay in a compact format for the early diagnosis of Alzheimer's disease (AD). For conducting the assay, we used human sera of 40 subjects divided into halves, which were grouped into AD patients and control groups according to a number of neuropsychological tests. We found that on an average, the concentrations of both total tau and phosphorylated tau proteins (all known to be higher in cerebrospinal fluid (CSF) and the brain) turned out to be higher in human sera of AD patients than in controls. The limits of detection of total tau and phosphorylated tau proteins were 2.4 pg mL⁻¹ and 1.6 pg mL⁻¹, respectively. In particular, it was found that the AD group exhibited average concentration of total tau proteins 6-fold higher than the control group, while concentration of phosphorylated tau proteins was 3-fold higher than that of the control. We can attribute this inhomogeneity between both types of tau proteins (in terms of increase of control-to-AD in average concentration) to un-phosphorylated tau proteins being more likely to be produced in blood than phosphorylated tau proteins, which possibly is one of the potential key elements playing an important role in AD progress.

In this work, SiO₂ nanoparticles were prepared by the sol-gel method after sodium silicate was extracted from rice husk ash (RHA) under various experimental conditions such as types of acids, NaOH concentration, dissolved time, and temperature and used for removal of Fe²⁺ ions from aqueous solutions. The extracted SiO₂ was morphologically and chemically characterized and showed a surface area of 78 m²/g and uniform pores of 2.71 nm, offering high adsorption capacity for Fe²⁺ ions. The influence of pH, contact time, and amount of adsorbent was studied in order to establish the best conditions for the Fe²⁺ adsorption and removal. Furthermore, the adsorption data were fitted with an exponential shape curve for all the three variable parameters that affect the adsorption process. The best results were obtained for pH 5, 20 min contact time, and 0.5 g adsorbent dose. The loading adsorption capacity was 9 mg of Fe²⁺ ions/g SiO₂ in the concentration range 0.1–1.0 mgL⁻¹. In addition, the synthesized SiO₂ with the size of around 50 nm can be used for specific heavy metal removal and drug delivery, after modification of the SiO₂ surface with various functional groups.

We presented synthesis and physical characterization of iron oxide magnetic nanoparticles (Fe₃O₄) for biomedical applications in the size range of 10-30 nm. Magnetic nanoparticles were synthesized by the coprecipitation method, and the particles’ size was controlled by two different injection methods of sodium hydroxide (NaOH). The synthesized magnetic nanoparticles were then modified by using series of linkers including tetraethyl orthosilicate (TEOS), 3-aminopropyltriethoxysilane (APTES), and glutaraldehyde (GA) to generate the structure of Fe₃O₄/SiO₂/NH₂/CHO, which can be used for immobilization of protein A. Additionally, we used transmission electron microscopy (TEM), X-ray powder diffraction (XRD), vibrating-sample magnetometry (VSM), and Fourier-transform infrared spectroscopy (FTIR), for characterization of properties and structure of the nanoparticles. An immobilization of protein A on magnetic nanoparticles was studied with a UV-Vis spectrum (UV-Vis) and fluorescence electron microscopy and Bradford method. Results showed that an XRD spectrum with a peak at (311) corresponded to the standard peak of magnetic nanoparticles. In addition, the magnetic nanoparticles withd≥30 nm have higher saturation magnetizations in comparison with the smaller ones withd≤10 nm. However, the smaller magnetic nanoparticles offered higher efficiency for binding of protein A, due to the high surface/volume ratio. These particles with functional groups on their surface are promising candidates for biomedical applications, e.g., drug delivery, controlled drug release, or disease diagnosis in point-of-care test.

Adsorption is an efficient, cost-effective, and eco-friendly method for the treatment of phosphorus from wastewater. This work presents the adsorptive removal of phosphate ions in aqueous solution using coal slag (CS) from a thermal power plan. The surface morphological analysis showed that the CS particles were around 50 µm with a surface area of 9.20 m² g⁻¹ and adsorption average pore width of 6.42 nm, offering the high capability for phosphate ions adsorption. The optimising phosphate ions adsorption conditions were investigated based on various parameters, including contact time, pH, and amount of absorbent. The experimental results showed that the maximum loading adsorption capacity was 21.63 mg g⁻¹ in the concentration range of 0–30 mg L⁻¹ under optimising conditions (i.e. pH of 6, adsorbent dosage (0.1 g vol⁻¹ used) and contact time of 45 min). Furthermore, the use of CS offers several benefits like reducing the sample pre-treatment steps for costly, less time-consuming and reliable methods.

This work presented the removal of nitrate ions in aqueous solution based on silica nanoparticles (SiNPs), which were extracted from rice husk ash. The optimal conditions for nitrate ion adsorption were studied including pH, contact time, adsorbate concentration, and amount of absorbance. The surface morphological analysis showed that the SiNPs extracted (purity of 98) were around 50nm with a surface area of 30m²·g⁻¹ and adsorption average pore width of 2.72nm, offers possibility for high capability of nitrate ion removal. The experimental results showed that the nitrate ion capability of adsorption was obtained around 14.22mg·g⁻¹ with a concentration range from 0 to 25mg·L⁻¹ based on optimizing conditions including pH 6, contact time of 50 minutes, and SiNP dosage of 0.15g vol⁻¹. In addition, nitrate ion removal based on SiNPs will provide considerate benefits such as the reducing costly sample pretreatment steps, less time-consuming, and reliable methods for processing nitrate-polluted water.

Propranolol is one of the first medications of the beta-blocker used for antihypertensive drugs. This study reports the facile route for the synthesis of propranolol and its novel derivatives. Herein, propranolol synthesis proceeded from 1-naphthol and isopropylamine under mild and less toxic conditions. Novel propranolol derivatives were designed by reactions of propranolol with benzoyl chloride, pyridinium chlorochromate, and n-butyl bromide through esterification, oxidation reduction, and alkylation, respectively. The isolation and purity of compounds were conducted using column chromatography and thin-layer chromatography. Mass spectrometry and ¹H-NMR spectroscopy were applied to identify new compounds structure. Propranolol derivatives from 2-chlorobenzoyl chloride (compound 3), 2-fluorobenzoyl chloride (compound 5), and especially acetic anhydride (compound 6) manifested high yields and significantly increased water solubility. Six semisynthetic propranolol derivatives promise to improve antioxidative and biological activities.