Mesoporous Zinc Oxide Research Articles

Facile synthesis of mesoporous zinc oxide nanoparticle as a drug delivery system evaluated by IVIVE in PBPK modeling

This study focuses on the development of mesoporous zinc oxide nanoparticles (mZNPs) via the sol–gel technique, utilizing polyethylene glycol-6000 (PEG-6000) as a capping agent. The research aims to investigate the suitability of these nanoparticles for drug delivery purposes. The analysis of the synthesized material validates the existence of a hexagonal system of zinc oxide with space group P6 3cm and HRTM confirmed the crystallinity and morphology of the nanoparticles ranging from 15–20 nm, revealing the formation of pores attributed to the presence of PEG-6000. The mZNPs exhibit a BET surface area of 28.3 m2. g−1, with Langmuir surface area measurements indicating 46 m2. g−1. Analysis employing the BJH method outlines pore diameters ranging from approximately 2–5 nm at a relative pressure of around 0.99. Furthermore, these mZNPs demonstrated drug delivery attributes, with 43.3% loading efficiency and 80.33% entrapment efficiency for aspirin. Notably, the release kinetics of aspirin from the mZNPs were investigated in simulated fluids of varying pH, with the highest release (98.1%) observed in simulated intestinal fluid (pH 6.8). The formulation exhibits typical time-dependent release kinetics under mild pH conditions (7.4 and 6.8), while transitioning to erosion-controlled diffusion mechanisms in acidic pH conditions (1.2). Furthermore, mathematical models, including Higuchi’s, Korsmeyer’s, and Weibull’s, were employed to assess release kinetics, offering parameters for in-vitro to in-vivo pharmacokinetic predictions. In the framework of PBPK modeling, renal clearance was computationally simulated at a rate of 45 min−1, whereas biliary clearance was modeled to occur at 0.05 min−1. Utilizing these model-derived parameters, the projected half-life of aspirin administered via mZNPs was determined to be 3.1 h. The potential applications of these findings extend to the development of effective drug delivery systems, warranting consideration for future animal model studies involving aspirin and mZNPs.

Enhanced methylene blue dye sequestration by carbon-embedded mesoporous zinc oxide nanoparticles fabricated utilizing Aloe barbadensis miller biowaste: Batch optimization, simulation modeling, and textile effluent feasibility

The present study reports novel carbon-embedded mesoporous zinc oxide nanoparticles (ZnO/C NPs) utilizing Aloe barbadensis miller (Aloe vera) biowaste extract as size-reducing agent and bio-stabilizer via a one-pot green fabrication approach. The fabricated nanoparticles were carbonized at 250 °C and characterized using FTIR, UV-Vis, ZPA, TEM, SEM/EDX, XRD, BET, and TGA techniques. Using Brunauer, Emmett, and Teller's theory, the ZnO/C NPs specific surface area was determined to be 63.25 m2/g, and the average pore diameter (3.46 nm) was in the mesoporous range. Fabricated ZnO/C NPs have an un-uniform size distribution, with an average crystallite size of 17.37 nm. The methylene blue (MB) dye adsorption of mesoporous ZnO/C NPs was studied in batch mode experiments at 37 °C using an aqueous solution. Detailed isotherms and kinetics modeling were performed, and it established that the Langmuir isotherm and Pseudo second order kinetic correctly fit the optimized MB dye adsorption data due to their higher correlation coefficients than other analyzed models. The Langmuir isotherm-based monolayer adsorption was found to be 105.26 mg/g. The pseudo second order kinetic best explains the adsorption reaction, indicating that the chemisorption mechanism is more likely to regulate the MB dye adsorption. Further, thermodynamics parameters showed that the MB dye adsorption onto ZnO/C NPs was spontaneous, endothermic, and accompanied by increased entropy. The ZnO/C NPs demonstrated remarkable MB dye sequestration from aqueous solution upto four reusability cycles, with regenerability of ≥84.52 %. Furthermore, feasibility study revealed an outstanding decolorization efficacy of MB dye upto 58.18 % from textile effluent, establishing mesoporous ZnO/C NPs as viable, environment-friendly, and cost-effective remedies for textile wastewater treatment.

Mesoporous zinc oxide-based drug delivery system offers an antifungal and immunoregulatory strategy for treating keratitis

Fungal keratitis is a refractory eye disease that is prone to causing blindness. Fungal virulence and inflammatory responses are two major factors that accelerate the course of fungal keratitis. However, the current antifungal drugs used for treatment usually possess transient residence time on the ocular surface and low bioavailability deficiencies, which limit their therapeutic efficacy. In this work, natamycin (NATA)-loaded mesoporous zinc oxide (Meso-ZnO) was synthesized for treating Aspergillus fumigatus keratitis with excellent drug-loading and sustained drug release capacities. In addition to being a carrier for drug delivery, Meso-ZnO could restrict fungal growth in a concentration-dependent manner, and the transcriptome analysis of fungal hyphae indicated that it inhibited the mycotoxin biosynthesis, oxidoreductase activity and fungal cell wall formation. Meso-ZnO also promoted cell migration and exhibited anti-inflammatory role during fungal infection by promoting the activation of autophagy. In mouse models of fungal keratitis, Meso-ZnO/NATA greatly reduced corneal fungal survival, alleviated tissue inflammatory damage, and reduced neutrophils accumulation and cytokines expression. This study suggests that Meso-ZnO/NATA can be a novel and effective treatment strategy for fungal keratitis.

Synthesis and characterization of mesoporous zinc oxide nanoparticles and evaluation of their biocompatibility in L929 fibroblasts.

This study aimed to synthesize and characterize mesoporous zinc oxide nanoparticles (ZnO NPs) and also to evaluate the cytotoxicity of mesoporous ZnO NPs on L929 mouse fibroblast cell lines using 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The synthesized mesoporous ZnO NPs were extensively characterized using X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectra (EDAX), Fourier-transform infrared spectroscopy (FTIR), and dynamic light scattering (DLS). The cytotoxicity of mesoporous ZnO NPs was assessed by MTT assay. The study groups for cytotoxicity assay were normal saline, 0.1% calcined mesoporous ZnO NP solution, 1% calcined mesoporous ZnO NP solution, 0.1% noncalcined mesoporous ZnO NP solution, 1% noncalcined mesoporous ZnO NP solution, 0.1% ZnO NP solution, 1% ZnO NP solution, 2% chlorhexidine, and phosphate-buffered saline (PBS). The percentages of mean ± standard deviation of viable cells were analyzed. Characterization of mesoporous ZnO NPs revealed that all the particles were in a more or less spherical shape with a wide particle size distribution of 70-100 nm. TEM image showed the uniformed and aggregated ZnO NPs with a typical size of 10-15 nm. BET analysis showed a mesoporous structure for the prepared mesoporous ZnO NPs. According to the MTT assay, chlorhexidine had the lowest cell viability percentage. Cell viability percentages of 0.1% mesoporous ZnO NP solutions (calcined and noncalcined) were statistically, significantly higher than 0.1% ZnO NP solution (p < .05). Cell viability percentages of 0.1% calcined and noncalcined mesoporous ZnO NP solutions and 0.1% ZnO NP solution were statistically, significantly higher than the 1% solutions (p < .05). Mesoporous ZnO NPs exhibited less cytotoxicity against L929 mouse fibroblast cell lines compared to CHX and ZnO NPs, hence are safe to use.

Ultrasmall Cu Nanoparticles Supported on Crystalline, Mesoporous ZnO for Selective CO2 Hydrogenation

AbstractConverting CO2 to value‐added chemicals, e. g., CH3OH, is highly desirable in terms of the carbon cycling while reducing CO2 emission from fossil fuel combustion. Cu‐based nanocatalysts are among the most efficient for selective CO2‐to‐CH3OH transformation; this conversion, however, suffers from low reactivity especially in the thermodynamically favored low temperature range. We herein report ultrasmall copper (Cu) nanocatalysts supported on crystalline, mesoporous zinc oxide nanoplate (Cu@mZnO) with notable activity and selectivity of CO2‐to‐CH3OH in the low temperature range of 200–250 °C. Cu@mZnO nanoplates are prepared based on the crystal‐crystal transition of mixed Cu and Zn basic carbonates to mesoporous metal oxides and subsequent hydrogen reduction. Under the nanoconfinement of mesopores in crystalline ZnO frameworks, ultrasmall Cu nanoparticles with an average diameter of 2.5 nm are produced. Cu@mZnO catalysts have a peak CH3OH formation rate of 1.13 mol h−1 per 1 kg under ambient pressure at 246 °C, about 25 °C lower as compared to that of the benchmark catalyst of Cu−Zn−Al oxides. Our new synthetic strategy sheds some valuable insights into the design of porous catalysts for the important conversion of CO2‐to‐CH3OH.

Injectable Zn2+ and Paeoniflorin Release Hydrogel for Promoting Wound Healing.

As more and more superbugs emerge, wounds are struggling to heal due to the inflammation that accompanies infection. Therefore, there is an urgent need to reduce the abuse of antibiotics and find nonantibiotic antimicrobial methods to counter infections to accelerate wound healing. In addition, common wound dressings struggle to cover irregular wounds, causing bacterial invasion or poor drug release, which reduces the wound healing rate. In this study, Chinese medicinal monomer paeoniflorin which can inhibit inflammation is loaded in mesoporous zinc oxide nanoparticles (mZnO), while Zn2+ released from mZnO degradation can kill bacteria and facilitate wound healing. The drug-loaded mZnO was encapsulated by a hydrogel formed from oxidized konjac glucomannan and carboxymethyl chitosan via rapid Schiff base reaction to obtain an injectable drug-releasing hydrogel wound dressing. The immediate-formation hydrogel allows the dressing to cover any wound shape. In vitro and in vivo studies have demonstrated that the dressing has good biocompatibility and superior antibacterial properties, which can promote wound healing and tissue regeneration by promoting angiogenesis and collagen production, providing a promising perspective for the further development of multifunctional wound dressings.

Photocatalytic degradation activity of goji berry extract synthesized silver-loaded mesoporous zinc oxide (Ag@ZnO) nanocomposites under simulated solar light irradiation

Different approaches have been developed for the synthesis of various nanostructured materials with unique morphologies. This study demonstrated the photocatalytic and antimicrobial abilities of silver-loaded zinc oxide nanocomposites (Ag@ZnO NCs). Initially, ZnO with a unique mesoporous ellipsoidal morphology in the size range of 0.59 ± 0.11 × 0.33 ± 0.09 µm (length × width) was synthesized using aqueous precipitation in a mild hydrothermal condition (80 °C) with the aqueous fruit extract of goji berry (GB) (as an additive) and calcined in air at 200 °C/2 h and 250 °C/3 h. Powder X-ray diffraction (XRD) revealed the formation of a hexagonal phase of the wurtzite (WZ) structure. The average crystallite size of ZnO was 23.74 ± 4.9 nm as calculated using Debye–Scherrer’s equation. It also possesses higher thermal stability with the surface area, pore volume, and pore size of 11.77 m2/g, 0.027 cm3/g, and 9.52 nm, respectively. Furthermore, different mesoporous Ag@ZnO NCs loaded with face-centered cubic (fcc) silver nanoparticles (Ag NPs) in the range of 90–160 nm were synthesized by GB extract as a reducing and capping agent on the surface of ZnO after calcination in air. The immobilization of Ag NPs was confirmed by XRD, X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), FE-transmission electron microscopy (FE-TEM), and energy-dispersive X-ray spectroscopy (EDS). It was found that Ag0.2@ZnO NC (0.2 wt% of Ag) showed excellent photocatalytic degradation of both methylene blue (MB) (cationic) and congo red (CR) (anionic) dyes under simulated solar irradiation. The photocatalytic degradation of 99.3 ± 0.35% MB and 98.5 ± 1.3% CR occurred in 90 and 55 min, respectively, at room temperature by Ag0.2@ZnO NC. Besides, these NCs also showed broad-spectrum antibacterial activity against both Gram-positive and Gram-negative bacteria. The mechanistic concept of generating reactive oxygen species (ROS) by electron and hole charge (e‾/h+) carriers seems to be responsible for the photocatalytic degradation of commercial dyes and antibacterial activities by Ag@ZnO NCs. Thus, these silver-loaded mesoporous ellipsoidal ZnO NCs are promising candidates as photocatalysts for industrial/wastewater treatment as well as in antimicrobial therapeutics.

Electrogenerated Copper Supported Zinc Oxide for Degradation of 2,4-Dichlorophenol

Copper (Cu) was deposited on two different types of zinc oxide (ZnO), namely commercial ZnO (CZ) and mesoporous zinc oxide (MZ), using a simple electrolysis technique. The catalysts were characterized by XRD, FTIR, BET and UV-Vis DRS. The synergistic effect between Cu, CZ and MZ was tested in the degradation of 2,4-dichlorophenol (2,4-DCP) under visible light irradiation. Cu-MZ exhibited the best performance with 97% degradation compared to MZ, Cu-CZ, CZ and CuO with 80%, 70%, 55% and 49%, respectively. The introduction of Cu in CZ and MZ was found to decrease the band gap energy of ZnO from 3.20 to 3.05 eV and 2.90 to 2.60 eV, respectively. The role of Cu in reducing the band gap energy of Cu-CZ and Cu-MZ probably contributed significantly to the good photocatalytic degradation of 2,4-DCP.

Effective adsorption and removal of industrial dye from aqueous solution using mesoporous zinc oxide nanoparticles via metal organic frame work: equilibrium, kinetics and thermodynamic studies

Effective adsorption and removal of industrial dye from aqueous solution using mesoporous zinc oxide nanoparticles via metal organic frame work: equilibrium, kinetics and thermodynamic studies

Organic Template‐Free Synthesis of Mesoporous ZnO Microparticles by Sol‐Gel Method and Low‐Temperature Hydrothermal Treatment

Mesoporous zinc oxide microparticles were synthesized by the sol‐gel method, followed by hydrothermal treatment at three different temperatures (100°C, 120°C, and 140°C), confirming that the method is fast, simple, reproducible, and ecological. To carry out the synthesis of the samples, zinc acetate was used as a precursor and sodium hydroxide as a precipitating agent. From the results obtained, the sample that shows the highest mesoporosity was the one synthesized at a hydrothermal treatment temperature of 140°C, obtaining an average particle size of 5 μm and a pore diameter of 1.7 nm. The importance of the results obtained was that mesoporous xerogel microparticles were obtained without using any type of organic template.

Synthesis and characterization of mesoporous zinc oxide nanoparticles

In this investigation, highly crystalline and mesoporous Zinc oxide (ZnO) nanoparticles with the large surface area were synthesized without calcination. Furthermore, the effects of different pH values on structural, physicochemical and textural properties of ZnO nanoparticles were comprehensively investigated. Rietveld refinement implied that the pH variation had significant effects on the crystal structure of ZnO nanoparticles. The phase, molecular and elemental structures confirmed the formation of ZnO as a major phase in all nanopowders. The morphology of ZnO nanoparticles was irregular with an average size of 45 ± 9 nm. Both phase and atomic structures confirmed the polycrystalline arrangement of ZnO nanoparticles. Moreover, isotherms confirmed the mesoporous structure of all ZnO nanoparticles with superior specific surface area and porosity volume. Thus, owing to the concoction of high crystallinity, superior surface area and porosity volume, resultant ZnO nanoparticles can be effectively employed for diverse multifunctional therapeutic applications.

Size-Controlled Au Nanoparticles Incorporating Mesoporous ZnO for Sensitive Ethanol Sensing.

Zinc oxide (ZnO) as a commonly used semiconductor material has aroused extensive research attention in various fields, such as field-effect transistors, solar cells, luminescent devices, and sensors, because of its excellent light-electrical features and large exciton bonding energy. Herein, ultrasmall Au nanoparticles with tunable size decorated mesoporous ZnO nanospheres were synthesized via facile formaldehyde-assisted metal-ligand cross-linking strategy, where these active Au species could be transferred into Au nanoparticles in the frameworks by various reduction strategies. Typically, mesoporous ZnO-Au with a photoreduction technique showed superior ethanol sensing performance (ca. 159 for 50 ppm at 200 °C) because of its high surface area, dual-mesoporous structure, and interface effect (electron effect, surface catalytic/adsorption). Moreover, the mesoporous ZnO-Au composites by photoreduction show much better performance than those via H2 reduction and NaBH4 reduction, which is ascribed to the providential size of Au nanoparticles (ca. 6.6 nm) and abundant oxygen defects in the composites. In particular, the selectivity and sensitivity of mesoporous ZnO-Au far exceeds those of materials loaded with other noble metals (Pt, Pd, and Ag). The sensing mechanism of mesoporous ZnO-Au for ethanol is attributed to classical surface adsorption/catalytic reaction, where strong sensitization effect (electron and chemical) and the spillover effect of Au nanoparticles in the catalytic reaction cause superior ethanol sensing performances. In situ FTIR and GC-MS measurement revealed that the catalytic oxidation of ethanol follows the process of dehydrogenation and deep oxidation, that is, dehydrogenation to acetaldehyde, and then further oxidation to carbon dioxide and water.

A statistical modeling-optimization approach for efficiency photocatalytic degradation of textile azo dye using cerium-doped mesoporous ZnO: A central composite design in response surface methodology

This paper investigates a new modeling approach of central composite design (CCD) in Response Surface methodology (RSM) for the optimization of methyl orange (MO) photodegradation based to the prepared materials under UV–vis irradiation. Mesoporous zinc oxide (ZnO) have been synthesized at different cerium (Ce) contents (2, 5 and 7wt%) through a single step sol gel method. Subsequently, cerium nanoparticles (CeNPs) have been impregnated on mesoporous ZnO. The physico-chemical characteristics of each catalyst are described through several approaches. The photocatalytic activity of the prepared catalysts shows that CeNPs enhance the photocatalytic performance of ZnO at 2wt% Ce content. MO photodergadation processes of the optimal catalyst can be mathematically described as a function of pH-solution, catalyst dosage and MO concentration being modeled by a CCD-RSM.Based on a statistical modeling (quadratic regression) and an optimization process (ANOVA analysis), the optimum conditions were achieved for pH of solution of 5.58, MO concentration of 20.72mgL−1and catalyst dosage of 0.63gL−1 which allowed reaching 100% of photodegradation. Overall, the value of the adjusted coefficient of determination (R2=0.9901) indicates that the considered model was quite suitable and that the selected CCD-RSM was successful in optimizing the photodegradation conditions of MO.

Effective degradation of sulfur mustard simulant using novel sulfur-doped mesoporous zinc oxide under ambient conditions

Sulfur doped metal oxides were synthesized using a two-step precipitation method. When reacted against neat 2-CEES (2-chloroethyl-ethyl sulfide, a mustard gas simulant) under ambient conditions, sulfur doped mesoporous zinc oxide (MS-Zn) showed higher catalytic activity than the other metal oxides with 92.7% overall conversion in 24 h for a 2.5 μL neat 2-CEES droplet added on top of 2 × 2 cm large 400 mg catalyst layer. The reaction proceeded mainly by hydrolysis and further solvolysis reaction also occurred depending on the extracting solvents. Cyclic sulfonium ion intermediate reaction was thought to be involved in this reaction, and metal oxide surfaces were thought to facilitate the formation of sulfonium ions from adsorbed 2-CEES. All other by-products were also found to form via sulfonium ions, reconfirming the well-known importance of this intermediate species for the degradation reaction to proceed. The sulfur content for MS-Zn was varied and tested for degradation of neat 2-CEES. This modification showed that there is an optimal amount of sulfur content for the peak catalytic activity of MS-Zn for 2-CEES degradation. Adsorption energy of a 2-CEES molecule was calculated on model sulfur doped and non doped zinc oxide surfaces and the different adsorption energy levels were correlated with the catalytic activity of sulfur doped zinc oxide.

Synthesis and characterization of TiO2/ZnO–Ag nanocomposite for photocatalytic degradation of dyes and anti-microbial activity

Abstract TiO2/ZnOnanocomposite was decorated by brightening silver nanoparticles (Ag NPs) The sol-gel technique was used in this analysis to assess the composition of titanium oxide nanoparticles @ mesoporous zinc oxide nanoparticles (MSNPs) (TiO2/ZnO)The TiO2/ZnO–Ag nanocomposite was portrayed by field outflow checking electron magnifying instrument (FESEM), vitality dispersive X-beam spectroscopy (EDAX), X-beam diffraction (XRD), diffuse reflectance spectroscopy (DRS), Fourier change infrared spectroscopy (FT-IR), Raman spectroscopy and UV–Visible spectroscopy. The FE-SEMexamination showed that the Ag NPs are constantly spread on the TiO2/ZnOnanocomposite that could strengthen its photocatalysts action exceptionally well. In addition, XRD investigation confirmed the proximity of Ag nanoparticles onto TiO2/ZnOnanoporousdistribution. The TiO2/ZnO–Ag nanomaterial showed better photo catalyst execution regarding degrading Alizarin and Crystal Violet with the photograph synergist debasement proficiency of 92 and 95% individually under direct daylight enlightenment. These results revealed that the TiO2/ZnO – Ag nanomaterial could be combined as a possible photo catalytic for dye degradation and antimicrobial activity.

Doping cadmium oxide into mesoporous zinc oxide matrix for enhanced removal /reduction of Hg(II) ions

A surfactant F-127 was used to synthesize highly crystalline mesoporous ZnO nanoparticles (NPs) through sol gel process. The CdO NPs at four different percentages (1, 2, 3, and 4%) were deposited on the mesoporous ZnO matrix through an impregnation approach. The photocatalysts have been evaluated by the determination of rate of Hg(II) removal/reduction in presence formic acid as sacrificial holes compared to the commercial P-25 and undoped ZnO NPs under visible light exposure. The removal/reduction efficiency over mesoporous CdO/ZnO heterostructures was significantly promoted, and their photoreduction efficiency was achieved to 25, 65, 95 and 96% at 1, 2, 3 and 4% CdO/ZnO heterostructures, respectively compared to undoped ZnO (4%) and P-25 (6.9%). The maximum Hg(II) removal/reduction efficiency of 100% was achieved at optimized values over 3% CdO/ZnO heterostructure, which exhibited noticeably ~23.7 and 13.7 times higher than undoped ZnO NPs and P-25. Interestingly, the rate constant of 3% CdO/ZnO photocatalyst was significantly enhanced 46.9 and 27.7 times than that undoped ZnO NPs and P-25, respectively. The optimum 3%CdO/ZnO photocatalyst exhibited great potential for removal/reduction Hg(II) performance due to its small particle sizes, narrow bandgap, large surface area, and high crystallinity.

Cur-loaded ZnFe2O4@mZnO@N-GQDs biocompatible nano-carriers for smart and controlled targeted drug delivery with pH-triggered and ultrasound irradiation

In the present study a pH/ultrasound (US)-responsive nano-carriers based on magnetic core-shell ZnFe2O4@mZnO@GQDs and ZnFe2O4@mZnO@N-GQDs ternary composite was prepared. The smart nano-carrier contain a magnetic zinc ferrite (ZnFe2O4) core, mesoporous zinc oxide (mZnO) and graphene quantum dots doped with nitrogen (N-GQDs) interlayer shell that prepared by sol-gel and/or the hydrothermal methods. This nano-carrier was used for pH/ultrasound-controllable curcumin (Cur) reagent release. The structural, thermal and morphological properties of each nano-carrier was investigated by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray (EDX), surface area measurements, transmission electron microscopy (TEM), selected area electron diffraction pattern (SAEDP) image, field emission scanning electron microscopy (FESEM), vibrating sample magnetometer (VSM), thermo gravimetric analyzer (TGA), dynamic light scattering (DLS), zeta potential, and Brunauer−Emmett−Teller (BET). Also, the cytotoxicity assay of nano-carriers have been studied on the fibroblast and Hela cells. No in vitro cytotoxic effects have observed at high concentration (75 μg/mL) of nanocarriers. The Cur drug loading efficiency of nano-carriers were as high as 76.45% w/w (ZnFe2O4@mZnO-N-GQDs) and 64.71% w/w (ZnFe2O4@mZnO-GQDs). The loaded Cur can be sustainably released, and could be controlled by US irradiation and pH adjustment. Thus, these core-interlayer-shells are suitable for smart and controlled targeted drug release by using pH and US irradiation.

Biodegradable and Drug-Eluting Inorganic Composites Based on Mesoporous Zinc Oxide for Urinary Stent Applications.

Conventional technologies for ureteral stent fabrication suffer from major inconveniences such as the development of encrustations and bacteria biofilm formation. These drawbacks typically lead to the failure of the device, significant patient discomfort and an additional surgery to remove and replace the stent in the worst cases. This work focuses on the preparation of a new nanocomposite material able to show drug elution properties, biodegradation and eventually potential antibacterial activity. Poly(2-hydroxyethyl methacrylate) or the crosslinked poly(2-hydroxyethyl methacrylate)-co-poly(acrylic acid) hydrogels were prepared by the radical polymerization method and combined with a biodegradable and antibacterial filling agent, i.e., flower-like Zinc Oxide (ZnO) micropowders obtained via the hydrothermal route. The physico-chemical analyses revealed the correct incorporation of ZnO within the hydrogel matrix and its highly mesoporous structure and surface area, ideal for drug incorporation. Two different anti-inflammatory drugs (Ibuprofen and Diclofenac) were loaded within each composite and the release profile was monitored up to two weeks in artificial urine (AU) and even at different pH values in AU to simulate pathological conditions. The addition of mesoporous ZnO micropowders to the hydrogel did not negatively affect the drug loading properties of the hydrogel and it was successfully allowed to mitigate undesirable burst-release effects. Furthermore, the sustained release of the drugs over time was observed at neutral pH, with kinetic constants (k) as low as 0.05 h−1. By exploiting the pH-tunable swelling properties of the hydrogel, an even more sustained release was achieved in acidic and alkaline conditions especially at short release times, with a further reduction of burst effects (k ≈ 0.01–0.02 h−1). The nanocomposite system herein proposed represents a new material formulation for preparing innovative drug eluting stents with intrinsic antibacterial properties.

Photo sensitizing and electrochemical performance analysis of mixed natural dye and nanostructured ZnO based DSSC

The paper highlights the enactment of the natural dyes, like purple cabbage, spinach, turmeric and their mixture as a photo-sensitizer, with nanostructured zinc oxide (ZnO) as a photo-anode, based dye-sensitized solar cell (DSSC). The field emission scanning electron microscopic image of ZnO, prepared by chemical bath deposition process, proclaims two different types of morphology, nano-wire and nano-plate shape. The photo sensitizing properties of the natural dyes and their mixed part are explored through FTIR spectra and UV-vis light absorbance characteristics. The FTIR spectra explore the presence of different anchoring chemical groups which confirm the strong anchoring bond with ZnO and enhancement of electron mobility. The diffused reflectance spectra (DRS) of dye-loaded ZnO films incisive the absorption of dye on the mesoporous ZnO surface. The relative energy band positions of individual and mixed dye, yield stable execution of the cell that has been performed through the cyclic voltammeter. The driving force energy requirement for effortless transport of electron from the mixed dye to the conduction band of ZnO is revealed lowers (0.34 eV) as compared to individual dyes. Electrochemical impedance spectroscopy (EIS) analysis has been executed to find the charge transfer resistance, total bulk resistance, recombination loss through Nyquist plots and Bode plots. These characteristics pretense as the mixed dye has an eminent rate of electron transportation and lower recombination loss with longer electron lifetime. The photon to electrical power conversion efficiencies of purple cabbage, spinach, turmeric and their mix dyes are explored as 0.1015%, 0.1312%, 0.3045%, and 0.602%, respectively under same simulated light condition. The mixed dye reveals the stable performance of the cell with the highest conversion efficiency due to the absorption of an extensive range of the solar spectrum and well-suited electrochemical responses.

Integration of mesoporous ZnO and Au@ZnO nanospheres into sensing device for the ultrasensitive CH3COCH3 detection down to ppb levels

Surface modification of metal oxide nanostructures with noble metals has attracted significant attention of researchers because of their importance in gas sensing applications. In this regard, mesoporous zinc oxide nanospheres (ZnO NSs) were designed through a simple template-free solvothermal approach and successive anchoring of gold nanoparticles (Au NPs) onto it was achieved through a chemical process followed by thermal treatment. The synergistic effects of different Au NPs loadings onto the structure, surface morphology, element contents, as well as chemiresistive gas sensing activities of solvothermal-mediated ZnO NSs were examined thoroughly and discussed. Gas sensing studies demonstrated that the sensor based on Au@ZnO-3 NSs exhibits excellent acetone (CH3COCH3) sensing characteristics (Response = 194) compared to pristine ZnO NSs sensor (Response = 2.86) at a lower temperature of 170 °C. Besides, Au@ZnO NSs sensor is able to detect CH3COCH3 concentration down to ppb-levels (500 ppb) with excellent response repeatability. Observed CH3COCH3 sensing performances of all the Au loaded ZnO NSs sensors were found to be almost 50 times higher than pristine ZnO NSs sensor. Such an excellent CH3COCH3 sensing performance of Au@ZnO NSs is mainly credited to the catalytic activity of Au NPs and the strong metal-semiconductor contacts between Au NPs and ZnO NSs.