Current Nanoscience - Volume 15, Issue 6, 2019

Nephrotoxicity, a chronic renal disease that results from the accumulation of endogenous and exogenous toxins in the kidney, disturbs the excretion and detoxification function of the kidney. Metal-mediated nephrotoxicity is induced by toxic metals/metalloids such as mercury, lead, arsenic, chromate, uranium, and cadmium. These materials become concentrated in the kidneys and injure the nephrons. Developing strategies to detect these metal ions will enable the earlier identification of kidney damage. An aptamer, an artificial antibody generated against a wide range of targets including metal ions, may be the right tool for the detection of metal ions associated with renal injury. The use of a detection system consisting of an aptamer and metallic nanoparticles is a potential way to overcome nephrotoxicity. Here, we discuss the detection of metal-mediated nephrotoxicity caused by metals/metalloids using the aptamer and nanomaterial-conjugated system.

Fluoride, arsenic, and nitrate are considered as major pollutants of water around the world, affecting millions of people mainly through the potable groundwater. Presence of these contaminants in drinking water can cause health issues like dental fluorosis, skeletal fluorosis, blackfoot disease, blue-baby syndrome, reproductive disorders, skin cancer, thyroid dysfunction, hypertension etc. The removal of fluoride, arsenic, and nitrate is mainly carried out through ion-exchange, membrane, adsorption, and other chemical treatments. Owing to the cost competitiveness, energy consumption and customized operating procedure, adsorption has been a popular choice for the removal of these contaminants. The adsorbent based on natural material either in native form or modified at the surface, have gained the momentum to be utilized for fluoride, arsenic, and nitrate free drinking water because of their adequate disposability. Recently, adsorbent of nanomaterial has shown the significant potential for water treatment because of their higher surface area and tailored selectivity. Nanoadsorbents prepared by wet-chemical precipitation, co-precipitation, sol-gel, electro-coextrusion, hydrothermal, thermal refluxing methods etc. can be effectively employed at comparatively lower concentration for water treatment. The adsorption capacity, durability, recyclability, and toxicity of nano-adsorbent are further explored particularly, at commercial scale. The present article is mainly aimed to provide a comprehensive review about the applicability and challenges associated with the use of nano-adsorbents for the removal of fluoride, arsenic, and nitrate with a brief discussion on options and future perspective to meet the challenges of complexity for the selection of environmentfriendly adsorbents.

According to the drug discovery, approximately 40% of the new chemical entities show poor bioavailability due to their low aqueous solubility. In order to increase the solubility of the drugs, self-micro emulsifying drug delivery systems (SMEDDS) are considered as an ideal technology for enhancing the permeability of poorly soluble drugs in GI membranes. The SMEDDS are also generally used to enhance the oral bioavailability of the hydrophobic drugs. At present, most of the self-microemulsion drugs are liquid dosage forms, which could cause some disadvantages, such as the low bioavailability of the traditional liquid SMEDDS. Therefore, solid self-micro emulsifying drug delivery systems (S-SMEDDS) have emerged widely in recent years, which were prepared by solidifying a semi-solid or liquid self-emulsifying (SE) ingredient into a powder in order to improve stability, treatment and patient compliance. The article gives a comprehensive introduction of the study of SMEDDS which could effectively tackle the problem of the water-insoluble drug, especially the development of solidification technology of SMEDDS. Finally, the present challenges and the prospects in this field were also discussed.

The intestinal tract is a complex and important physiological and immunological organ. Intestinal tract homeostasis requires a series of coordinated interactions involving gut microbiota, the crypt intestinal stem cells (ISC) and the surrounding niche, including the intestinal epithelial cells, endothelial cells, dendritic cells, and macrophages. The destruction of intestinal homeostasis leads to autoimmune diseases, such as inflammatory bowel disease (IBD). IBD is a non-specific, and remittent- relapsing inflammatory disorder of the gastrointestinal tract. There is no effective method to keep patients in remission for a long term. It has been reported that extracellular vesicles (EVs) exert immune activation and immunosuppressive effects in the pathogenesis of IBD. In order to explore new therapeutic strategies for IBD, in this review, we summarize the observations on the immune properties and functions of EVs in intestinal mucosal immunity.

Background: As a high-performance functional material, stacked piezoelectric actuator can produce a displacement under the effect of changing voltage. Its advantages of fast response and easy operation make it to be widely applied in the precision structure field. However, its small displacement stroke and hysteresis nonlinearity affect the accuracy of the output. Methods: In order to enlarge the displacement of piezoelectric actuator and reduce the influence of hysteresis, this study designs a diamond-shaped amplifying mechanism to amplify the output of the piezoelectric actuator, and then develops a self-tuning fuzzy fractional-order PIλDμ controller for the high precision displacement control of the proposed amplifying mechanism. After analyzing the working principle and modeling the amplifying mechanism, the fractional-order PIλDμ control model of the proposed mechanism was built and discretized according to the theoretical base of the fractional calculus in the time domain. Moreover, the fuzzy control algorithm was also introduced to achieve self-turning of parameters. Besides, the amplifying mechanism was also adopted for a microdroplet jetting dispenser to verify the practicability of the mechanism and control strategy. In the next step, some experiments were undertaken based on the constructed platform. Results: Experiments show that the displacement overshoots, the times of reaching a steady state of the traditional integer-order controller and the fractional-order controller are 5.08%, 1.17% and 17.25 s, 12.00 s, respectively. However, the fuzzy PIλDμ controller lowers the overshoot and the time of reaching a steady state to 0.95% and 9.00 s, respectively. The control algorithm can not only improve the follow-ability of the output displacement of the proposed mechanism, but also maintain the deviation within the range of 0.4% after the displacement stroke is stable and reduce the entering time of the mechanism up to 47.8%. In actual application, the droplet volume of micro-droplet jetting dispenser under fuzzy fractional-order PID control method is more stable, and its repeatability accuracy can reach up to 1.6475%. Conclusion: Experimental results indicate that the self-tuning fuzzy fractional-order PIλDμ controller can significantly improve the tracking performances of the PID and the integer-order PID with regard to the amplifying mechanism with the advantages of good dynamic character and regulation precision. Furthermore, the diamond-shaped amplification mechanism and control strategy can be applied for some micro-droplet jetting dispensers used in microelectronic packaging, life science and 3D printing fields.

Background: Graphene-Titanium dioxide nano-composite forms a very promising material in the field of photo-electrochemical research. Methods: In this study, a novel environment-friendly synthesis method was developed to produce well-distributed anatase nano-titanium dioxide spherical particles on the surface of graphene sheets. This novel method has great advantages over previously developed methods of producing graphenetitanium dioxide nanocomposites (GTNCs). High calcination temperature 650°C was used in the preparation of nano titanium dioxide, and chemical exfoliation for graphene synthesis and GTNC was performed by our novel method of depositing titanium dioxide nanoparticles on graphene sheets using a Y-shaped micro-reactor under a controlled pumping rate with minimal use of chemicals. Results: The physiochemical and crystallographic properties of the GTNC were confirmed by TEM, XRD, FTIR and EDX measurements, confirming process repeatability. Spherical nano-titanium dioxide was produced in the anatase phase with very high crystallinity and small particle diameters ranging from 9 nm to 25 nm, also the as prepared graphene (RGO) exhibited minimal flake folding and a high carbon content of 81.28% with a low oxygen-to-carbon atomic ratio of 0.172 and GTNCs produced by our novel method had a superior loading content, a homogeneous distribution and a 96.6% higher content of titanium dioxide particles on the graphene sheets compared with GTNCs prepared with the one-pot method. Conclusion: For its photoelectrochemical properties, chronoamperometry showed that GTNC sample (2) had a higher peak current of 60 μA compared with that of GTNC sample (1), which indicates that the separation and transfer of electron-hole pairs are better in the case of GTNC sample (2) and according to the LSV results, the generation of photocurrent in the samples can be observed through multiple on-off cycles, which indicates that the electrodes are stable and that the photocurrent is quite reversible.

Background: Chitosan-multiwall carbon nanotubes (CS-MWCNTs) nanocomposites are an attractive material due to their biocompatibility and possibility to produce nanocomposites with high conductivities and high mechanical properties. Both electrical and mechanical properties depend upon the method of MWCNT chemical oxidation; this oxidation affects the interaction of CS side groups with MWCNT’s surface groups. However, in the literature, there are no reports on how different methods of MWCNT oxidation will affect the electrical and mechanical properties of related nanocomposites. Objective: The objective of this work is to probe CS-MWCNT nanocomposite’s electrical and mechanical properties by taking advantage of the presence of interfacial layer and its dependence on the methods of MWCNTs chemical oxidation routes. Methods: Nanocomposites are prepared with non-functionalized MWCNT and functionalized MWCNTs obtained by chemical oxidation treatments in HNO3 in H2SO4/NHO3 mixtures and commercially carboxyl-terminated MWCNTs, respectively. Properties of MWCNTs and nanocomposites were evaluated using SEM, FTIR, Raman, TGA, XRD, impedance and mechanical measurements. Results: It was shown that different chemical oxidation routes produce MWCNTs with a different number of carboxylic groups and defects which influence the interaction between MWCNTs with CS matrix and thickness of the interfacial layer between MWCNTs and CS matrix. Additionally, it was shown that the formation of the interfacial layer dominates on the dispersion of MWCNTs and affects on the electrical and mechanical percolation effects. Conclusion: It was shown that contrary to many studies previously reported, good dispersion of MWCNT does not guarantee obtained nanocomposites with the best electrical and mechanical properties.

Background: As progress on the nanofabrication has made semiconductor developed rapidly, there is an increasing need in precise pitch standards to calibrate the structure of devices at nanoscale. Nano-gratings fabricated by atom lithography are unique and suitable to act as precise pitch standard because its pitch distance is directly traceable to a natural constant. As the scaling down of nano-devices, it is very challenging to double the spatial frequency of nano-grating while keeping the self-traceability in atom lithography. Methods: In this study, the switching-detuning light mask is utilized for Cr atom lithography. During a single deposition process, the standing wave frequency is switching from positive detuning to negative detuning alternatively. Results: Nano-gratings fabricated using switching-detuning light mask is successfully replicated with double spatial frequency and self-traceability. Non-uniformity between neighboring Cr lines shows up with a corrected pitch of 107.15±0.35 nm. Conclusion: Non-uniformity is mainly caused by the dipole force discrepancy between positive and negative detuning light mask. Therefore, to increase the high uniformity of nano-gratings, the deposition time of negative detuning should be at least twice as the positive detuning. On the other hand, to reduce the pitch uncertainty, it is necessary to reduce the distance between the atom beam and reflection mirror as close as possible. These two significant optimization designs are promising to increase the spatial frequency doubling performance with high uniformity and accuracy.

Background: In this comprehensive study, the influence of titanium dioxide (TiO2) dopants decorated on Reduced Graphene Oxide (rGO) via spin coating technique as an efficient photoelectrode in DSSCs was investigated in detail. Objective: This study aims to determine the optimum spinning duration for decorating TiO2 onto rGO nanosheet photoanode for high DSSCs performance. Methods: The rGO nanosheet was prepared using the electrodeposition method. A dropped of 0.2 wt% of TiO2 solution was absorbed using micro-pipette (0.1 μl) and continuously applied on FTOrGO surface with the rate of 0.1 μl/5s. The spinning duration was varied from 10 to 50 s, and resultant samples were labelled as Lt, where t= 10, 20, 30, 40 and 50s, respectively. Results: The experimental results showed that TiO2 decorated rGO nanosheet photoanode for 30s spinning duration exhibited a maximum power conversion efficiency of 9.98% than that of pure rGO nanosheet photoanode (4.74%) under 150 W of xenon irradiation, which is about 2.1 times improvement in DSSCs performance. Conclusion: Ti4+ ion was decorated onto rGO nanosheet leading to the highest interactions with the O-H functional group or Ti4+ could react with the epoxide or phenolic groups in rGO forming the Ti- O-C bonds.

Background: The present research describes a mild and efficient method for the synthesis of 3,4-dihydropyrimidine-2(1H)-thiones and thiazolopyrimidine via multi-component reactions using FeCo2O4 nanoparticles. It was found that FeCo2O4 nanoparticles act as a powerful and effective catalyst. The prepared catalyst was characterized by the various spectroscopic techniques. Objective: The three-component reaction of thiourea, aromatic aldehydes and ethyl acetoacetate was catalyzed by FeCo2O4 nanoparticles. Next, the prepared 3,4-dihydropyrimidin-2(1H)-thiones were applied for the preparation of thiazolopyrimidines via the reactions of 3,4-dihydropyrimidine-2(1H)- thiones, chloroacetic acid, and aromatic aldehydes in the presence of FeCo2O4 nanoparticles. Methods: The FeCo2O4 nanoparticles were synthesized by a facile one-step method and the structure determination of the catalyst has been done using spectral techniques. Then, the prepared nanocatalyst was used in the synthesis of 3,4-dihydropyrimidin-2(1H)-thiones and thiazolopyrimidines under solvent-free conditions at 80°C. Results: FeCo2O4 nanoparticles as a magnetic nanocatalyst were applied as a catalyst in the synthesis of some heterocyclic compounds in excellent yields and short reaction times. The average particle size of the catalyst is found to be 30-40 nm. The study on the reusability of the FeCo2O4 nanoparticles showed the recovered catalyst could be reused fifth consecutive times. We propose that FeCo2O4 nanoparticles act as a Lewis acid cause to increase electrophilicity of carbonyl groups of substrates and intermediates to promote the reactions. 2 Conclusion: The present research introduced various advantageous including excellent yields, short reaction times, simple workup procedure and recyclability of the FeCo2O4 NPs in order to the synthesis of 3,4-dihydropyrimidin-2(1H)-thiones and thiazolopyrimidines.

Background: It is necessary to investigate the performances of the optimized tree-type cylindrical-shaped nanoporous filtering membranes with 3 or 5 branch pores in each pore tree. Objective: To explore the design method for and the performances of the liquid-particle and liquidliquid separations of the optimized tree-type cylindrical-shaped nanoporous filtering membranes with 3 or 5 branch pores in each pore tree. Methods: The analysis was made for the flow resistance of the studied membrane based on the nanoscale flow equation. The optimum ratios of the radius of the trunk pore to the radius of the branch pore were typically calculated for yielding the lowest flow resistance of this membrane. The capability of the liquid-liquid separation of this membrane was investigated by exploring the flow resistances of this membrane for different liquids. Results: The optimum ratios of the radius of the trunk pore to the radius of the branch pore were typically calculated for the maximum fluxes of these membranes for different passing liquid-pore wall interactions. They can be used for the design of the studied membranes for liquid-particle or liquid-liquid separations. The flow resistances of the studied membranes in the optimum condition for different liquids were also calculated, and the capability of the liquid-liquid separation of the membranes is evidenced. Conclusion: The obtained results can be used for the design of the studied membranes for achieving their optimum operating condition, by taking the ratio of the radius of the trunk pore to the radius of the branch pore as optimum. The studied membranes also have good capabilities of liquid-liquid separations if the mixed liquids have greatly different interactions with the pore wall and the radius of the branch pore is below 3nm or less.

Background: Direct methanol fuel cells as a clean and efficient energy conversion method for portable electronic devices and electric vehicles are a very popular subject in science and engineering. Up to now, the most effective anode electrode materials for direct methanol fuel cells are Pt- Ru, used mainly as bimetallic catalysts dispersed on a highly active conductive support, such as conducting polymer, carbon-based catalysts, or a composite matrix composed of both. Objective: The main objective is to decrease the amount of precious metal-Pt required for financial considerations and to overcome the insufficient oxidation reactions’ rate of the fuel, which lead to the inevitable, naturally high, overpotential in fuel cell applications. Thereby, current research addresses the preparation of Pt, Pt-Ru, Pt-Ru-Pd and Pt-Ru-Mo metal nanoparticles modified by both polyaniline-multi-wall carbon nanotubes and polianiline-functionalized multi-wall carbon nanotubes composites and their activity in the methanol electro-oxidation. Methods: All of the composite surfaces were successfully prepared using electrochemical methodologies. A Citrate method was used for the preparation of metal nanoparticles. A comparative study was conducted on each stage of the investigation. The modified surfaces were characterized and analyzed by SEM, EDX, XRD, Raman, and TEM. Results: According to the spectroscopic measurements, all particles synthesized were detected as nanoscale. Binary and ternary catalysts supported on composite surfaces had higher activity and efficiency when compared to monometallic systems. Conclusion: The fabricated electrodes showed comparable catalytic activity, long-term stability, and productivity towards direct methanol fuel cell applications in acidic media.

Background: Ordered arrays of 1D iron(oxyhydr)oxide nanostructures have potential applications in magnetic recording mediums, lithium batteries, supercapacitors, and thermal production of α-, β-, γ-type Fe2O3. Large surface areas with three-dimensional architectures, such as nanotubes, are encouraged because the easy access of ion, gas, liquid and radiation assures high ion exchange capacity, sensing and catalytic activities. Objective: In this work, the morphological evolution of Fe-oxyhydroxide electrodeposition inside AAM pores has been followed for the first time by selecting two relevant electrochemical conditions of synthesis producing high quality morphologies of nanotubes. Methods: Iron(oxyhydr)oxide nanotubes have been synthesized by cathodic electrodeposition at a constant current in classic three-electrode cell. Two different electrolytic baths have been studied: (i) an aqueous bath consisting of 5 mM FeCl3+5 mM KF+0.1 M KCl+1 M H2O2 (H-Fe) and (ii) an ethanolic bath consisting of 0.3 M FeCl3 + 0.1 M KCl (Et-Fe). Results: XRD, Raman and SEM results on the iron(oxyhydr)oxide nanotubes suggest different mechanisms of chemical precipitation mechanisms in Et-Fe alcoholic solution (dehydration and rearrangement within the ferrihydrite aggregates) and H-Fe aqueous solution (dissolution/ reprecipitation). The morphological evolution of the growing nanostructure to nanotubes inside AAM in the two baths agrees very well with the overpotential vs. time curves, the kinetic growth of the nanotubes arrays and a growth mechanism governed by the relative mass transfer processes involving both OH- and Fe ions. Conclusion: The morphological evolution of Fe-oxyhydroxide cathodic electroprecipitation inside AAM pores in two relevant electrochemical baths containing Fe(III) (aqueous/H-Fe and alcoholic/Et- Fe) has been followed for the first time by a comprehensive SEM analysis accompanied by electrochemical, structural and kinetic growth of the nano-electrodeposits. The detailed SEM results collected in this work allowed to recommend template electrogeneration of base in ethanol solution containing Fe(III) chloride as a relevant procedure to obtain high-quality, compact and well-ordered Fe oxy-hydroxide nanotubes.