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Here, for the first time, one or few-layer exfoliated 2D-Biotene (E-BIT) was prepared by a cost-effective liquid-phase exfoliation of economical and accessible bulk biotite (B-BIT). The successful preparation of E-BIT was further verified by different characterization methods. XRD pattern demonstrated that B-BIT's basal spacing was increased from 10.07 Å to 11.02 Å. Also, the transparency of the E-BIT to the electron beam showed its small thickness after exfoliation, which was confirmed by AFM results, too. This natural material was utilized as an efficient nano-additive to improve the properties of polyethersulfone (PES) polymeric membrane. E-BIT blended membranes with various quantities (0-2 wt%) were prepared via the non-solvent induced phase inversion method. Small holes at the up layer, coarse finger-like holes and macro-voids at the sublayer were seen in asymmetric prepared membranes. Modification caused the improvement of the membranes' hydrophilicity, which the contact angle was reduced from 69.3 to 53.4 for bare PES and 1 wt% E-BIT blended membranes, respectively. 1 wt% E-BIT blended membrane illustrated flux enhancement of 198.8 L/m2 h, and high elimination efficiency of bovine serum albumin (99%), reactive red 195 (97.8%), reactive green 9 (93.5%), and reactive blue 19 (88.4%), with improved flux recovery ratio of 73%.

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In this research work, the Ti2SnC MAX phase (MP) was synthesized via the reactive sintering procedure. The layered and crystalline structure of this MP was verified by SEM, HRTEM, and XRD analyses. This nano-additive was used for improvement of different features of the polyethersulfone (PES) polymeric membranes. The blended membranes containing diverse quantities of the MP (0-1 wt%) were fabricated by a non-solvent-induced phase inversion method. The asymmetric structure of the membranes with small holes in the top layer and coarse finger-like holes and macro-voids in the sublayer was observed by applying SEM analysis. The improvement of the membrane's hydrophilicity was verified via reducing the contact angle of the membranes from 63.38° to 49.77° (for bare and optimum membranes, respectively). Additionally, in the presence of 0.5 wt% MP, the pure water flux increased from 286 h to 355 L/m2 h. The average roughness of this membrane increased in comparison with the bare membrane, which shows the increase in the filtration-available area. The high separation efficiency of the oil/water emulsion (80%) with an improved flux recovery ratio of 65% was illustrated by the optimum blended membrane.

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In this research work, it has been reported a ratiometric fluorescent sensor based on tungsten disulfide quantum dots (WS2 QDs) and fluorescein for the determination of Cefixime (CEF). When excited by radiation of 400 nm wavelength the probe illustrates dual emissions centered at 460 nm and 510 nm. CEF quenches the fluorescence (FL) intensity of fluorescein (510 nm), while it doesn't affect the FL emission of WS2 QDs at 460 nm. The change in the ratio of the two peaks (F460/F510) of the prepared sensor (WS2 QDs/fluorescein) is linearly proportional to the CEF concentration in the range of 200-2.500 ng/mL with a limit of detection (LOD) of 45 ng/mL. Hence, the proposed probe can be successfully used for CEF quantification in the milk samples.

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Cerium doped magnetite nanoparticle (CDM) was synthesized via a co-precipitation method and used as the co-reactant of luminol-K3Fe(CN)6 chemiluminescent system. The physical-chemical features of CDM were studied by XPS, XRD, HRTEM, FESEM, VSM, BET, and FTIR analyses. This simple and highly sensitive nanoprobe enabled the determination of minor concentrations of metronidazole (MNZ). Owing to the quenching efficacy of MNZ in the studied chemiluminescence system, a linear range of 3.47 × 10-6-9.37 × 10-5 mol/L was obtained with a limit of detection of 3.91 × 10-7 mol/L. This biosensor was used for MNZ detection in human serum samples, which was highly efficient. The outcomes of this study give credit to the proposed biosensor to be applied for detection of MNZ in biological samples.

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Currently, researchers are looking for nanomaterials with peroxidase-like activity to replace natural peroxidase enzymes. For this purpose, WS2 quantum dots (WS2 QDs) were synthesized via a solvothermal method, which improved the mimetic behavior. The resulting WS2 QDs with a size of 1⁻1.5 nm had a high fluorescence emission, dependent on the excitation wavelength. WS2 QDs with uniform morphology showed a high catalytic effect in destroying H2O2. The peroxidase-like activity of synthesized nanostructures was studied in H2O2 chemical and electrochemical reduction systems. The mimetic effect of WS2 QDs was also shown in an H2O2⁻rhodamine B (RB) chemiluminescence system. For this aim, a stopped-flow chemiluminescence (CL) detection system was applied. Also, in order to confirm the peroxidase-like effect of quantum dots, colorimetry and electrochemical techniques were used. In the enzymatic reaction of glucose, H2O2 is one of the products which can be determined. Under optimum conditions, H2O2 can be detected in the concentration range of 0⁻1000 nmol·L-1, with a detection limit of 2.4 nmol·L-1. Using this CL assay, a linear relationship was obtained between the intensity of the CL emission and glucose concentration in the range of 0.01⁻30 nmol·L-1, with a limit of detection (3S) of 4.2 nmol·L-1.

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It is reported that a mixture of WS2 nanosheets (WS2 NS) and silver nanoclusters (AgNCs) displays strongly enhanced peroxidase-mimicking activity. The catalytic effect of the mixture was studied by colorimetry, fluorometry, chemiluminescence (CL) and electrochemistry. The effect is interpreted in terms of a difference between the Fermi energy level of the two nanomaterials. This leads to the formation of charge separation regions which act as active sites for enzyme mimetic interaction with the substrates. The mixture of WS2 NS and AgNCs was exploited for the non-enzymatic determination of H2O2 and glucose. A stopped-flow method was applied as a sensitive CL detection system using the bicarbonate-H2O2 reaction. The mixture has a powerful peroxidase mimicking activity on the bicarbonate-H2O2 CL reaction, and this effect is much larger than that of any single constituent. In addition, the CL emission is improved several times by using the stopped-flow technique. Under optimum condition, H2O2 can be determined in the 2.5-1500 nM concentration range. Moreover, glucose levels in human serum can be quantified via glucose oxidase based oxidation which leads to the generation of H2O2. Using this CL assay, a linear relationship was obtained between the intensity of the CL emission and glucose concentration in the range of 0.03-20 µM, with a limit of detection (3S) of 13 nM. Graphical abstract An enhanced peroxidase-like catalytic activity for WS2 nanosheets (WS2 NS) was revealed in the presence of silver nanoclusters (AgNCs), and was exploited for the non-enzymatic determination of H2O2, and of glucose (via glucose oxidase; GOx) using a stopped-flow CL method.

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Developing a novel peroxidase nano-mimetic is a challenging research topic in biosensing field. Herein, WS2 nanosheets (WS2 NS) decorated with silver nanoclusters (AgNCs) was introduced as a new nanocomposite with improved peroxidase mimetic behavior. WS2 NS/AgNCs nanocomposite was synthesized by simple chemical reduction of silver cations in the presence of WS2 NS. The enhanced catalytic activity of nanocomposite in chemical and electrochemical reduction of H2O2 was studied using colorimetry, fluorometry and electrochemical techniques. Attaching the AgNCs on the surface of WS2 NS effectively improved the catalytic activity of these nanosheets, which may be connected to the difference of the Fermi energy levels of coupled nanomaterial. The unequal Fermi levels cause charge separation between two phases creating highly active sites on the interface of coupled nanomaterial. Moreover, the new mimetic nanocomposite was applied for the analysis of glucose in blood, based on its enzymatic oxidation using glucose oxidase and then, on the measurement of produced H2O2 by sensitive fluorescence detection system. In optimum condition, a linear association was found between the generated fluorescence intensity and glucose logarithmic concentration in the range of 0.05-400 µM, and the limit of detection (3S/m) was 21 nM.