Surface-modified Zinc Oxide Research Articles

Gelatin‑sodium alginate composite hydrogel doped with black phosphorus@ZnO heterojunction for cutaneous wound healing with antibacterial, immunomodulatory, and angiogenic properties

Hydrogels with novel antimicrobial properties and accelerated wound healing are of great interest in the field of wound dressings because they not only prevent bacterial infections but also fulfill the essential needs of wound healing. In this study, multifunctional hydrogel dressings consisting of black phosphorus nanosheets(BPNS) surface-modified Zinc oxide (BP@ZnO heterojunction) based on gelatin (Gel), sodium alginate (SA), glutamine transferase (mTG), and calcium ions with a three-dimensional crosslinked network were prepared. The BP@ZnO-Gel/SA hydrogel has excellent mechanical properties, hemocompatibility (hemolysis rate: 3.29 %), swelling rate(832.8 ± 19.2 %), cytocompatibility, photothermal and photodynamic antibacterial properties(Sterilization rate: 96.4 ± 3.3 %). In addition, the hydrogel accelerates wound healing by promoting cell migration, immune regulation and angiogenesis. Thus, this hydrogel achieves the triple effect of antimicrobial, immunomodulation and angiogenesis, and is a tissue engineering strategy with great potential.

Multi Jet Fusion of surface-modified ZnO nanorod–reinforced PA12 nanocomposites

ABSTRACT Metal oxide nanorods exhibit promising potential as reinforcement fillers in various polymer matrices, but their application in the Multi Jet Fusion (MJF) technique is rarely reported. In this work, surface-modified zinc oxide nanorods (SMZnO) were synthesized and incorporated into polyamide 12 (PA12) powder to enhance the mechanical properties of the MJF-printed parts. Compared to ZnO, SMZnO exhibited better dispersion, resulting in markedly enhanced mechanical performances. The ultimate tensile strength and the Young's modulus of the MJF-printed SMZnO/PA12 nanocomposites were 62.02 MPa and 2.28 GPa in the X orientation and 64.07 MPa and 2.34 GPa in the Y orientation, equivalent to 27.85%, 59.44%, 29.12%, and 54.97% increments, respectively. The flexural strength and modulus demonstrated similar improvements in the X and Y orientations, confirming the uniform mechanical enhancement effect of homogenously distributed SMZnO. This work provides a novel and facile approach for the additive manufacturing of polymeric nanocomposites with superior mechanical performance.

Beta vulgaris extract assisted green synthesis of ZnO nanoparticles: antimicrobial and nano priming studies

In this present study, we report the synthesis of surface-modified zinc oxide (ZnO) nanoparticles (NPs) using chemical method (Z) as well as green method using Beta vulgaris extract (BvZ). The band gap energy of BvZ (3.14 eV) was found to be greater than that of Z (3.0 eV) owing to its smaller particle size. The X-ray diffraction patterns reveal the reduction in crystallite size for BvZ when compared to Z. TEM and SEM images show the agglomeration of particles for BvZ and spherical morphology for Z. The XPS spectra of the BvZ NPs were studied to confirm the oxidation state of Zn ions. Antimicrobial activities of BvZ and Z were tested against bacterial strains such as Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus cereus and fungal strains viz., Candida tropicalis, and Aspergillus niger. The seed germination property of BvZ for chickpea seeds was also studied.

Synthesis of functionalized ZnO nanoflake loaded polyvinylidene fluoride composites with enhanced energy storage properties

AbstractPolymer composite films are ideal materials for advanced energy storage capacitor in electrical systems. Therefore herein, we fabricated a novel series of polyvinylidene fluoride (PVDF) based composites embedded with well dispersed ZnO@APTES {surface modified zinc oxide with (3‐Aminopropyl) triethoxysilane (APTES)} nanoflake (0, 20, 30, 40, 50) vol% through solution casting method. Hydrothermally synthesized two‐dimensional ZnO was pre‐treated with H2O2 and surface modified with APTES for perfect distribution of nanoflake into PVDF matrix. Surface modification and high aspect ratio morphology of ZnO@APTES enhanced the interfacial interaction between organic PVDF and inorganic ZnO through reduction in heterogeneity between them. Surface functionalization reduced the dielectric loss and improved the overall energy storage performance. Investigation of electrical properties proclaimed incorporating 30 Vol% ZnO@APTES in PVDF as optimized loading due to its appreciable Wrec (recoverable energy density) about 3.2 J/cm3. Relative comparison of the energy storage density (Wrec) of PVDF/ZnO@APTES (30) vol% with recent published works established its enhanced capacitive response and its future application in energy storing portable device.

Fabrication of hydrophilic luminescent zinc oxide quantum dots for selective detection of copper ions and efficient inhibition of harmful fungi

In this study, we have successfully prepared surface modified zinc oxide quantum dots (M-ZnO QDs) with ultra-stable fluorescence and excellent hydrophilicity through introducing (3-aminopropyl)triethoxysilane (APTES). The as-prepared M-ZnO QDs under the optimum condition presented strong yellow fluorescence emission under 355 nm excitation and showed satisfied reproducibility. Physical and chemical properties of the synthesized ZnO QDs were further studied by various characterization techniques. Transmission electron microscopy showed homogeneous distribution of spherical M-ZnO QDs with the average particle size of 4.03 nm. According to the characteristic that metal ions can quench fluorescence, M-ZnO QDs-based fluorescence sensor for the detection of Cu 2+ in aqueous solution is developed in this work, which has the advantages of excellent selectivity, good sensitivity and a wide linear range. The limit of detection was 0.51 μM and the linear detection range was 1–200 μM for Cu 2+ determination. The practicability of the fluorescent probe is further validated in the lake water and the satisfactory spiked recoveries of Cu 2+ ranges from 99.1 % to 108.8 %. Besides, M-ZnO QDs displayed concentration inhibition effect and strain effect on the growth of fungi. Thus, the as-prepared M-ZnO QDs are demonstrated to be promising for Cu 2+ determination and anti-fungal applications.

Effect of alkali bases on the synthesis of ZnO quantum dots

Abstract The surface-modified zinc oxide quantum dots (ZnO QDs) have broad application prospects in the field of biomedicine because of their good water solubility, dispersibility, and high fluorescence stability. The alkali bases play important roles in controlling the morphology, size distribution, dispersity, and fluorescence intensity of the synthesized ZnO QDs. In this article, ZnO QDs were synthesized to induce hydrolysis–condensation reaction. The influences of alkali bases (LiOH, NaOH, and KOH) and the ratio of n(Zn2+):n(OH−) on the properties of synthesized ZnO QDs were investigated. The results show that the particle size of the ZnO QDs prepared using LiOH and NaOH as raw materials are smaller than that using KOH. ZnO QDs prepared at the ratio of n(Zn2+):n(LiOH) = 1:1 have the best fluorescence performance and dispersibility.

Surface modification of zinc oxide nanoparticles by vinyltriethoxy silane (VTES)

Zinc oxide (ZnO) nanoparticles are hydrophilic in nature and difficult to disperse in polymer matrix due to agglomeration behavior. To disperse the zinc oxide nanoparticles in polymer matrix, it is necessary to modify their surface with hydrophobic groups such as silanes or surfactants. In this article, zinc oxide nanoparticles were modified with various concentration of vinyl triethoxysilane (VTES). To investigate the effect of different concentrations of VTES, on surface modification of zinc oxide nanoparticles, these were characterized using physical characterization techniques such as Fourier-transform infrared spectroscopy (FTIR), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), Energy Dispersive X-rays Spectroscopy (EDX), X-ray diffraction (XRD) and contact angle. The results of FTIR, TGA, SEM, EDX and contact angle confirm the surface modification of zinc oxide nanoparticles by VTES. The XRD results show that the crystalline behavior of ZnO nanoparticles was not changed after surface modification by VTES. The crystallite size of surface modified ZnO nanoparticles was calculated using Debye-Scherrer equation and it was found approx 20 nm. In FTIR results, some new peaks at 1409, 1014 and 970 cm−1 were observed as compare to unmodified zinc oxide nanoparticles. In contact angle analysis, it was observed that the surface modified zinc oxide nanoparticles have very high contact angle (greater than150°) in comparison with hydrophilic behavior of unmodified zinc oxide nanoparticles. SEM analysis also showed the improved dispersity of ZnO nanoparticles. Based on characterization results, it was observed that the 15 wt% VTES concentration is suitable to carry out surface modification of ZnO nanoparticles.

Fast NMR relaxation, powder wettability and Hansen Solubility Parameter analyses applied to particle dispersibility

The selection of appropriate solvents into which inorganic and organic sub-micron particles can be dispersed is important for product manufacturability and performance. Molecular-level interactions determine solvent suitability but are difficult to measure; existing experimental approaches require slow/expensive tests of dispersion stability. Solvent relaxation NMR measurements are shown to be a fast indicator of solvent suitability, with sensitivity to the solvent-particle intermolecular forces making it a reliable proxy for stability measurements. A structured approach to relaxation measurements with a selection of both good and poor solvents yields the Hansen Solubility Parameters (HSP) for the particle surface. Suitable solvents can be selected from a database of HSP values, and solvents can be blended to match the particle interface. The application of the approach is illustrated using a range of surface modified zinc oxide and aluminum oxide particles, with similarities and differences between the particle surfaces becoming evident through the analysis.

Enhanced photocatalytic decolorization of Congo red dye with surface-modified zinc oxide using copper(II)–amino acid complex

Photocatalytic decolorization of Congo red dye has been investigated using surface-modified ZnO nanoparticles by adsorbing copper(glycinato) complex on the surface of nanosized ZnO. The complex-adsorbed photocatalyst is shown to exhibit enhanced photodecolorization of the dye compared to the pure ZnO nanoparticles. Effect of catalyst dose, initial dye concentration, and role of H2O2 as oxidizing agent has been studied in order to optimize the condition for efficient decolorization. The nanosized ZnO was prepared by precipitation method onto which the amino acid complex was adsorbed. The synthesized catalysts were characterized by XRD, UV, FTIR, SEM, and EDAX. Comparative evaluation of photodecolorization of the dye was investigated for both the nanosized ZnO and the complex-adsorbed ZnO nanoparticles under optimized conditions.

Stable and sustainable photoanodes using zinc oxide and cobalt oxide chemically gradient nanostructures for water-splitting applications

Amorphous cobalt oxide (CoO) encapsulated zinc oxide (ZnO) nanostructures were developed by adopting three low-temperature methods respectively atomic layer deposition, chemical bath deposition, and electrochemical deposition. The impact of CoO growth on the physical and chemical properties of ZnO nanostructures was investigated. Then, the ZnO/CoO core/shell nanostructures grown under optimized conditions were adopted for the fabrication of photoelectrochemical (PEC) water-splitting devices. The catalytic performance of ZnO nanostructures is substantially improved after their encapsulation with CoO layers. In addition, the chemical stability and durability of the structures are significantly enhanced. Under typical measurement conditions, these surface-modified ZnO nanostructures exhibited incident photon to charge carrier conversion efficiency (IPCE) higher than 16%, and a stable photocurrent density of 1.25 mA cm−2. Further, these ZnO/CoO nanostructured photoanodes showed a high illumination to dark current density ratio, ~2910.

Surface Modified Zinc Oxide Nanoparticles as Smart UV Sensors

The present paper examines the synthesis of ZnO nanoparticles and their surface modification via the microwave assisted sonochemical method along with its successful application in designing a smart UV sensor. The structure of the prepared samples was investigated using XRD, XPS and its respective crystallinity studies. The photoluminescence spectroscopy identified an increase in the green emission intensity due to surface modification which is attributed to the density of oxygen vacancies. The variation in the dielectric constant and dielectric loss values with surface modification is clearly substantiated. As a case study, it was observed a smart UV sensor fabricated using this surface modified ZnO response and decay time that are 14 s and 16 s, respectively. Also, the possibility of surface modification in tuning the sensing responses has been investigated in detail.

Fabrication of surface modified ZnO nanorod array for MALDI-MS analysis of bacteria in a nanoliter droplet: a multiple function biochip

We demonstrated the use of surface modified zinc oxide nanorod (ZnO NR) array chip for on-plate detection, pre-concentration, separation and subsequently matrix-assisted laser desorption/ionization mass spectrometric (MALDI-MS) analysis for bacteria present in nanoliter liquid droplet. The surface modified ZnO NR array can be easily fabricated on Zn foil via chemical method. To explore the potential of the fabricated ZnO NR array chip as a MALDI-MS chip and substrate, standard proteins were studied. It was observed that surface modified ZnO NR array substrates provides significant enhancement on analyte ionization in comparison to the conventional MALDI target plate and efficiently suppress the background noises. This significantly leads to clean mass spectra with high resolution and excellent signal intensity. Furthermore, the proposed method was demonstrated for the analysis of bacteria in nanoliter droplets with high reproducibility and it can be further employed as an effective affinity probe to detect and separate the bacteria from sea water and urine. The lowest detectable concentration of the bacteria cells is 1.9 × 102 cfu μL−1 and the minimum volume required for the sample analysis is 50 nano-liter (nL). We believe that this multiple function biochip can serve as an effective bacteria detecting platform in the near future.

Characterization and Colloidal Stability of Surface Modified Zinc Oxide Nanoparticle

This paper mainly studies the characterization and colloidal stability of surface modified zinc oxide nanoparticle and pure zinc oxide nanoparticle. According to IUPAC definition, ultrafine particles are always in the range of within 100 nm called nano-sized particle which expressed in term of perfect spherical diameter. Nanotechnology has immersed into various sector of oil and gas industries. In recent decades, vast amount of research has been done using zinc oxide nanoparticle related products effect on disjoining pressure mechanism in porous medium, interfacial tension (IFT) and wettability. Several types of nanoparticles have been evaluated through interfacial tension and wettability. Disadvantage of poor colloidal stability of nanoparticle in fluid is aggregation and sedimentation which leads poor heat transfer. In this study, zinc oxide nanoparticle was used as core to be functionalized. Surfactant was used to surface modify ZnO nanoparticle. Surface modified ZnO nanoparticle and pure ZnO nanoparticle were characterized using Scanning Electron Microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). Stability and hydrodynamic size of surface modified and pure zinc oxide nanofluid are examined using Zetasizer Nano ZS. Rheological behavior of nanofluids were determined through rheometer. The peak of surface modified and pure ZnO nanofluid were 62.94 nm and 386.4 nm respectively. There is a decrease of 83.71% of hydrodynamic size of nanoparticle after surface modified. ZnO nanofluid has the stability of -14.2 mV while surface modified ZnO has the zeta potential of -45.4 mV. Increase of 219.72 % more stable compared to pure ZnO nanofluid. Pure ZnO nanofluid showed viscosity increment which could because of the sedimentation of nanoparticle occurs. Lower viscosity of surface modified ZnO nanofluid might due to SDS surfactant.

Exploiting in vitro potential and characterization of surface modified Zinc oxide nanoparticles of Isodon rugosus extract: Their clinical potential towards HepG2 cell line and human pathogenic bacteria.

Little is known about biogenically synthesized Zinc oxide nanoparticles (ZnONPs) from Isodon rugosus. Synthesis of metal oxide NPs from essential oil producing medicinal plants results in less harmful side effects to the human population as compared to chemically synthesized NPs. In this article, we report biogenic synthesis of ZnONPs from in vitro derived plantlets and thidiazuron (TDZ) induced callus culture of Isodon rugosus. Synthesized NPs were characterized using UV-spectra, XRD, FTIR, SEM and EDX. Furthermore, the NPs were evaluated for their potential cytotoxic (against HepG2 cell line) and antimicrobial (against drug resistant Staphylococcus epidermidis, Bacillus subtilis, Klebsiella pneumoniae and Pseudomonas aeruginosa) activities. Pure crystalline ZnONPs with hexagonal and triangular shapes were obtained as a result of callus extract (CE) and whole plant extract (WPE), respectively. ZnONPs showed potent cytotoxic and antimicrobial potential. The antimicrobial and cytotoxic activities of ZnONPs were found to be shape and surface bound phytochemicals dependent. CE mediated hexagonal ZnONPs showed superior anti-cancer and antimicrobial activities as compared to WPE mediated triangular shaped ZnONPs. It is concluded that biogenic ZnONPs have incredible potential as theranostic agents and can be adopted as useful drug delivery system in next generation treatment strategies.

Electrically insulating ZnOs/ZnOw/silicone rubber nanocomposites with enhanced thermal conductivity and mechanical properties

ABSTRACTIn this work, hybrids of surface modified zinc oxide spherical (ZnOs) nanoparticles and tetrapod‐shaped whiskers (ZnOw) were incorporated into the silicon rubber (SR) to prepare the ZnOs/ZnOw/SR nanocomposites. The incorporation of the ZnOs/ZnOw facilitated the formation of three‐dimensional thermally conducting network. It was found that the thermal conductivity of the ZnOs/ZnOw/SR reached up to 1.309 W m−1 K−1 when the ZnOs/ZnOw content was 20 vol % (Vm‐ZnOs:VZnOw = 7:3), which was nearly 6.5 times that of the pristine SR. The dielectric and resistivity measurements showed that the incorporation of the ZnOs/ZnOw hybrids did not cause much change in the electrical properties. In addition, the results show that the tensile strength of ZnOs/ZnOw/SR nanocomposites is higher than that of pristine SR. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46454.

Physicochemical characteristics and toxicity of surface-modified zinc oxide nanoparticles to freshwater and marine microalgae

Because of wide applications of surface-modified zinc oxide nanoparticles (ZnO-NPs) in commercial sunscreens and their easiness of being released into water, concerns have been raised over their potential effects on aquatic organisms. This study compared physicochemical properties of silane-coated and uncoated ZnO-NPs to elucidate their toxic potencies toward three freshwater and three marine microalgae. Surfaces of ZnO-NPs (20 nm) were modified by coating with 3-aminopropyltrimethoxysilane (A-ZnO-NPs) that provides the particles with a more hydrophilic surface, or dodecyltrichlorosilane (D-ZnO-NPs) that turns the particles to hydrophobic. Uncoated ZnO-NPs formed larger aggregates and released more Zn2+ than did either of the two coated ZnO-NPs. The three nanoparticles formed larger aggregates but released less Zn2+ at pH 8 than at pH 7. Although sensitivities varied among algal species, A-ZnO-NPs and uncoated ZnO-NPs were more potent at inhibiting growth of algal cells than were D-ZnO-NPs after 96-h exposure to ZnO, uncoated ZnO-NPs, each of the coated ZnO-NPs or ZnSO4 at 10 concentrations ranging from 0.1 to 100 mg/L. The marine diatom Thalassiosira pseudonana exposed to ZnO-NPs, A-ZnO-NPs or D-ZnO-NPs resulted in differential expressions of genes, suggesting that each of the coatings resulted in ZnO-NPs acting through different mechanisms of toxic action.

Effects of different surface modifying agents on the cytotoxic and antimicrobial properties of ZnO nanoparticles

Zinc oxide (ZnO) nanoparticles (NPs) have received considerable attention in the medical field because of their antibacterial properties, primarily for killing and reducing the activity of numerous microorganisms. The purpose of this study was to determine whether surface-modified ZnO NPs exhibit different properties compared with unmodified ZnO. The antimicrobial and cytotoxic properties of modified ZnO NPs as well as their effects on inflammatory cytokine production were evaluated. ZnO NPs were prepared using a wet chemical method. Then, the surfaces of these NPs were modified using 3-aminopropyltriethoxysilane (APTES) and dimethyl sulfoxide (DMSO) as modifying agents via a chemical hydrolysis method. According to infrared spectroscopy analysis (FTIR), the structure of the ZnO remained unchanged after modification. Antibacterial assays demonstrated that APTES modification is more effective at inducing an antimicrobial effect against Gram-negative bacteria than against Gram-positive bacteria. Cytotoxicity studies showed that cell viability was dose-dependent; moreover, pristine and APTES-modified ZnO exhibited low cytotoxicity, whereas DMSO-modified ZnO exhibited toxicity even at a low NP concentration. An investigation of inflammatory cytokine production demonstrated that the extent of stimulation was related to the ZnO NP concentration but not to the surface modification, except for IFN-γ and IL-10, which were not detected even at high NP concentrations.

Preparation, structural characterization, and gas separation properties of functionalized zinc oxide particle filled poly(ether-amide) nanocomposite films

In this study, a new diacid monomer containing amide, imide, and sulfone functional groups was successfully used to synthesize a new poly(ether-amide) for membrane-based gas separation applications. The synthesized poly(ether-amide) was soluble in organic solvents, has high thermal stability (up to 460℃ under nitrogen atmosphere, for 10% weight loss), and high glass transition temperature (Tg = 274℃). This poly(ether-amide) was combined with different amounts of surface-modified zinc oxide nanoparticles to provide organic–inorganic nanocomposites. The optically transparent and flexible membranes of these hybrid nanocomposites were prepared. The obtained materials were characterized by Fourier transform-infrared spectroscopy, thermal gravimetric analysis, differential scanning calorimetry, X-ray powder diffraction, field emission-scanning electron microscopy, and transmission electron microscopy techniques. Transmission electron microscopy of the nanocomposite film with 15 wt% zinc oxide confirms that the nanoparticles are well dispersed in the polymer matrix. Thermal gravimetric analysis data indicated that the hybrid materials had better thermal behavior with increasing surface-modified zinc oxide nanoparticles nanoparticle content. The poly(ether-amide)/surface-modified zinc oxide nanoparticles nanocomposite film mechanical properties improved with increasing surface-modified zinc oxide nanoparticles content. The permeability and selectivity of the poly(ether-amide)/zinc oxide membranes as a function of the surface-modified zinc oxide nanoparticles weight percentage were studied, and the results indicated that the CO2 and CH4 permeability increased with increasing zinc oxide content. In general, the membranes prepared from these polymers showed very good permeability and permselectivity for a pair of gases.

Optical properties of zinc oxide powders modified by nanoparticles ZrO2, Al2O3, TiO2, SiO2, CeO2 and Y2O3 with various concentrations

This study carried out on the diffuse reflective spectra of zinc oxide modified by Al2O3, ZrO2, SiO2, CeO2, TiO2 and Y2O3 nanoparticles. It was established that during the modification are formed the solid solutions between zinc oxide and nanopowder as Al2ZnO4, ZrZnO3, Zn2SiO4, CexZn(1−х)Оy, Zn2TiO4, YxZn(1−x)Oy. The diffuse reflection spectra of the modified powders are changed in the UV and visible range with a maximum at 395 nm. This band is determined by the intrinsic point defects in the crystal lattice of ZnO as interstitial zinc ions and zinc vacancy. In the IR region also recorded changes due to the absorption of OH-groups adsorbed on the surface modified zinc oxide.

Photoluminescence investigation of ZnO quantum dots surface modified with silane coupling agent as a capping agent

This report presents the luminescence measurement results of surface modified zinc oxide quantum dots (ZnO QDs) performed with different concentrations of 3-aminopropyltriethoxysilane (APTES) as a capping agent. Surface modification was performed by an in situ procedure on the surface of ZnO QDs in a sol gel solution route. The modified samples were characterized by various analytical techniques such as XRD, TEM, FT-IR, and UV–vis spectroscopy. Surface modification efficiency was experimentally investigated by variation of the photoluminescence) PL (emission intensities observed by changing the capping agent concentration. In order to investigate the effectiveness of the capping agent on the stability of the QDs, The PL spectra of the surface modified ZnO QDs were compared with that of unmodified ZnO QDs. Molecular layer of this type and similar silane based molecules with a variety of surface terminations that have the same molecular attachment schemes should enable interface engineering in optimizing the chemical selectivity of ZnO biosensors or electrical and optical properties of ZnO-polymer hybrid films.