Expediting the bioactivity of zinc sulfide nanoparticles with copper oxide as a nanocomposite

The regulatory role of zinc in bone formation extends to the activation of proteins associated with bone homeostasis. Furthermore, copper is well known for its antibacterial properties. This dual function underscores the significance of zinc and copper in maintaining a balance of bone structure and function. In light of the aforementioned, zinc sulphide/copper oxide nanocomposites were created in this instance using a straightforward coprecipitation technique. Copper oxide was used as a nanocomposite to improve the structural, morphological, and biological performance of zinc sulphide nanoparticles. The X-ray diffraction pattern confirmed a transformation in the crystal structure from cubic to rhombohedral, along with increase in intensity. Fourier transforms infrared analysis indicated the presence of functional groups. Scanning electron microscopy images demonstrated a morphological shift from non-uniform to distinct spherical nanoparticles, impacting the enhancement of material properties. The pathogenic activity of the zinc sulphide/copper oxide nanocomposites was tested against nine bacterial strains. In antimicrobial testing, zinc sulphide/copper oxide nanocomposites showed promising results, particularly against Klebsiella pneumoniae (zone of inhibition: 14 mm at 100 µg/mL compared to 7 mm by standard) and Escherichia coli (zone of inhibition: 11 mm at 100 µg/mL compared to 10 mm by standard) after 24 h with zone of inhibition matching or exceeding that of the standard (chloramphenicol). Zinc sulphide nanoparticles and zinc sulphide/copper oxide nanocomposites were evaluated for their antifungal activity against fungal stains from Trichophyton rubrum, Aspergillus niger, and Aspergillus flavus. After a 24-h period, it was discovered that zinc sulphide/copper oxide nanocomposites were effective against Aspergillus flavus (zone of inhibition: 19.4 mm at 100 µg/mL compared to 6.3 mm by standard) at all concentrations (25-100 mg/mL), with zones of inhibition identical to or greater than those of the standard (fluconazole). Certainly, based on these results, zinc sulphide/copper oxide nanocomposites could be promising materials for drug delivery.Clinical trial registration: Not applicable.

Psidium guajava-mediated green synthesis of Fe-doped ZnO and Co-doped ZnO nanoparticles: a comprehensive study on characterization and biological applications

The efficacy of nanoparticles (NPs) in healthcare applications hinges on their biocidal activity and biocompatibility. This research is dedicated to green-synthesized NPs with potent biocidal properties, aiming for high inhibition rates in bacterial infections and offering a multifunctional application, including potential use in anticancer therapy, in comparison to traditional antibiotics. The present study focuses on synthesis of zinc oxide (ZnO) nanoparticles (NPs), including iron-doped ZnO (GZF) and cobalt-doped ZnO (GZC), using the green co-precipitation method involving Psidium guajava (P. guajava) leaf extract. The physicochemical properties of the synthesized NPs were analyzed using various characterization techniques. The antibacterial and anticancer activity depends on the generation of reactive oxygen species (ROS), particle size, surface area, oxygen vacancy, Zn2+ release, and diffusion ability. The antibacterial activity of the synthesized NPs was tested against various Gram-positive (Streptococcus pneumoniae (S. pneumoniae), Bacillus subtilis (B. subtilis) and Gram-negative (Klebsiella pneumoniae (K. pneumoniae), and Pseudomonas aeruginosa (P. aeruginosa) bacterial strains. The zone of inhibition showed higher activity of GZC (18-20 mm) compared to GZF (16-19 mm) and GZO (11-15 mm) NPs. Moreover, anticancer studies against blood cancer cell line (MOLT-4) showed half-maximal inhibitory concentration of 11.3 μg/mL for GZC compared to GZF and GZO NPs with 12.1 μg/mL and 12.5 μg/mL, respectively. Cytotoxicity assessments carried out on the fibroblast L929 cell line indicated that GZO, GZF, and GZC NPs demonstrated cell viabilities of 85.43%, 86.66%, and 88.14%, respectively. Thus, green-synthesized GZC NPs hold promise as multifunctional agents in the biomedical sector.

Nanoengineered chitosan functionalized titanium dioxide biohybrids for bacterial infections and cancer therapy

Nanoengineered chitosan functionalized titanium dioxide biohybrids (CTiO2@NPs) were prepared with Amomum subulatum Roxb extract via one-pot green method and assessed by UV-Vis spectroscopy, XRD, SEM and EDAX analyses. As revealed by XRD pattern, the nanohybrids exhibits a rutile TiO2 crystallites around 45 nm in size. The emergence of the Ti-O-Ti bond is identified by observing a peak between 400 and 800 cm-1. A wide bandgap (4.8 eV) has been observed in CTiO2@NPs, due to the quantum confinement effects and the oxygen vacancies reveal the intriguing potential of developed nanohybrids for various applications. Surface flaws were identified by observing an emission band at 382, 437, 482, 517, and 556 nm. They also exhibit better antibacterial performances using well diffusion method against Staphylococcus aureus, Bacillus substilis, Klebsiella pneumonia, and Escherichia coli. CTiO2@NPs were discovered to have free radical scavenging activity on DPPH analysis and exhibit IC50 value as 95.80 μg/mL and standard (Vitamin C) IC50 is 87.62 μg/mL. CTiO2@NPs exhibited better anticancer properties against the osteosarcoma (MG-63) cell line. All these findings suggest that there is a forum for further useful therapeutic applications. Therefore, we claim that nano-engineered carbohydrated TiO2 phytohybrid is a promising solution for bacterial infections and bone cancer.

Toxicological assessment of divalent ion-modified ZnO nanomaterials through artificial intelligence and in vivo study

The nanotechnology-driven industrial revolution widely relies on metal oxide-based nanomaterial (NM). Zinc oxide (ZnO) production has rapidly increased globally due to its outstanding physical and chemical properties and versatile applications in industries including cement, rubber, paints, cosmetics, and more. Nevertheless, releasing Zn2+ ions into the environment can profoundly impact living systems and affect water-based ecosystems, including biological ones. In aquatic environments, Zn2+ ions can change water properties, directly influencing underwater ecosystems, especially fish populations. These ions can accumulate in fish tissues when fish are exposed to contaminated water and pose health risks to humans who consume them, leading to symptoms such as nausea, vomiting, and even organ damage. To address this issue, safety of ZnO NMs should be enhanced without altering their nanoscale properties, thus preventing toxic-related problems. In this study, an eco-friendly precipitation method was employed to prepare ZnO NMs. These NMs were found to reduce ZnO toxicity levels by incorporating elements such as Mg, Ca, Sr, and Ba. Structural, morphological, and optical properties of synthesized NMs were thoroughly investigated. In vitro tests demonstrated potential antioxidative properties of NMs with significant effects on free radical scavenging activities. In vivo, toxicity tests were conducted using Oreochromis mossambicus fish and male Swiss Albino mice to compare toxicities of different ZnO NMs. Fish and mice exposed to these NMs exhibited biochemical changes and histological abnormalities. Notably, ZnCaO NMs demonstrated lower toxicity to fish and mice than other ZnO NMs. This was attributed to its Ca2+ ions, which could enhance body growth metabolism compared to other metals, thus improving material safety. Furthermore, whether nanomaterials' surface roughness might contribute to their increased toxicity in biological systems was investigated utilizing computer vision (CV)-based AI tools to obtain SEM images of NMs, providing valuable image-based surface morphology data that could be correlated with relevant toxicology studies.

In the View of Electrons Transfer and Energy Conversion: The Antimicrobial Activity and Cytotoxicity of Metal-Based Nanomaterials and Their Applications

The global pandemic and excessive use of antibiotics have raised concerns about environmental health, and efforts are being made to develop alternative bactericidal agents for disinfection. Metal-based nanomaterials and their derivatives have emerged as promising candidates for antibacterial agents due to their broad-spectrum antibacterial activity, environmental friendliness, and excellent biocompatibility. However, the reported antibacterial mechanisms of these materials are complex and lack a comprehensive understanding from a coherent perspective. To address this issue, a new perspective is proposed in this review to demonstrate the toxic mechanisms and antibacterial activities of metal-based nanomaterials in terms of energy conversion and electron transfer. First, the antimicrobial mechanisms of different metal-based nanomaterials are discussed, and advanced research progresses are summarized. Then, the biological intelligence applications of these materials, such as biomedical implants, stimuli-responsive electronic devices, and biological monitoring, are concluded based on trappable electrical signals from electron transfer. Finally, current improvement strategies, future challenges, and possible resolutions are outlined to provide new insights into understanding the antimicrobial behaviors of metal-based materials and offer valuable inspiration and instructional suggestions for building future intelligent environmental health.

Solar Photocatalytic Activity of Ba-Doped ZnO Nanoparticles: The Role of Surface Hydrophilicity

Bare zinc oxide (ZnO) and Ba-doped ZnO (BZO) samples were prepared by using a simple precipitation method. The effects of Barium doping on the structural, morphological, and optoelectronic properties, as well as on the physico-chemical features of the surface were investigated and correlated with the observed photocatalytic activity under natural solar irradiation. The incorporation of Ba2+ ions into the ZnO structure increased the surface area by ca. 14 times and enhanced the hydrophilicity with respect to the bare sample, as demonstrated by infrared spectroscopy and contact angle measurements. The surface hydrophilicity was correlated with the enhanced defectivity of the doped sample, as indicated by X-ray diffraction, Raman, and fluorescence spectroscopies. The resulting higher affinity with water was, for the first time, invoked as an important factor justifying the superior photocatalytic performance of BZO compared to the undoped one, in addition to the slightly higher separation of the photoproduced pairs, an effect that has already been reported in literature. In particular, observed kinetic constants values of 8∙10-3 and 11.3∙10-3 min-1 were determined for the ZnO and BZO samples, respectively, by assuming first order kinetics. Importantly, Ba doping suppressed photocorrosion and increased the stability of the BZO sample under irradiation, making it a promising photocatalyst for the abatement of toxic species.

Enhancement of Photocatalytic and Photoelectrochemical Performance of ZnO by Mg Doping: Experimental and Density Functional Theory Insights

Doped ZnO nanostructures have shown great potential for solar energy applications. Considering the compatible ionic radius, Mg atoms can be doped into ZnO at different concentrations. The current work reports a combined experimental and density functional theory study on the influence of the Mg dopant concentration on ZnO performance simultaneously for photocatalytic dye removal and photoelectrochemical water splitting. Among all the samples, Mg(3)-ZnO (3 at. % Mg) exhibits superior sunlight-driven photocatalytic performance. The optimal Mg-ZnO shows an 8-fold increase in the photocatalytic activity compared to the pristine ZnO. Likewise, the most active photocatalyst shows high photoelectrochemical performance with a photocurrent response of 1.54 mA at the lowest onset potential, 11 times higher than the pristine ZnO. Tuning of the Mg content results in the generation of extra charge carriers and a reduced recombination rate, which are the crucial factors responsible for enhanced photocatalytic and photoelectrochemical performance.

ZnO and cobalt decorated ZnO NPs: Synthesis, photocatalysis and antimicrobial applications

The rapid growth of pollutants, both biological and non-biological, puts environmental systems in jeopardy. In view of this, the current study demonstrates the synthesis of undoped and Cobalt-doped zinc oxide nanoparticles (Co doped ZnO NPs) via co-precipitation method. The confirmation of incorporation of the Co dopant into ZnO NPs was verified through various spectroscopic and microscopic techniques. UV-absorption spectra of cobalt-doped ZnO NPs revealed a red shift with change of absorption spectra from 356 nm to 377 nm as compared to undoped ZnO NPs. XRD studies inferred that the average crystallite size of 0.5% and 1% Co-doped ZnO powder was obtained to be ∼16 nm and 14 nm respectively. A drop in band gap value from 3.48 eV to 3.30 eV provided as substantive evidence of the successful integration of Co²⁺ ions inside the ZnO matrix. FESEM and HRTEM studies revealed that the obtained ZnO NPs are in narrow size distribution (15-20 nm) with a wurtzite crystal structure. The synthesized ZnO and Co-ZnO NPs showed excellent photocatalytic and antimicrobial potency towards reactive brown dye (RB-1) and two bacterial strains, respectively. 1% Co-doped ZnO demonstrated the maximum photocatalytic activity (∼95%), in contrast to 0.5% Co-doped ZnO and undoped ZnO. Thus, the findings of this work support the developed system has a dual role as the photocatalyst, and antibacterial agent for efficient environmental remediation.

Dental Composites with Magnesium Doped Zinc Oxide Nanoparticles Prevent Secondary Caries in the Alloxan-Induced Diabetic Model

Antibacterial restorative materials against caries-causing bacteria are highly preferred among high-risk patients, such as the elderly, and patients with metabolic diseases such as diabetes. This study aimed to enhance the antibacterial potential of resin composite with Magnesium-doped Zinc oxide (Mg-doped ZnO) nanoparticles (NPs) and to look for their effectiveness in the alloxan-induced diabetic model. Hexagonal Mg-doped ZnO NPs (22.3 nm diameter) were synthesized by co-precipitation method and characterized through ultraviolet-visible (UV-Vis), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) analysis. The Mg-doped ZnO NPs (1, 2.5 and 5% w/w) were then evaluated for antibacterial activity using a closed system in vitro biofilm model. Significant enhancement in the antibacterial properties was observed in composites with 1% Mg-doped ZnO compared to composites with bare ZnO reinforced NPs (Streptococcus mutans, p = 0.0005; Enterococcus faecalis, p = 0.0074, Saliva microcosm, p < 0.0001; Diabetic Saliva microcosm, p < 0.0001). At 1−2.5% Mg-doped ZnO NPs concentration, compressive strength and biocompatibility of composites were not affected. The pH buffering effect was also achieved at these concentrations, hence not allowing optimal conditions for the anaerobic bacteria to grow. Furthermore, composites with Mg-doped ZnO prevented secondary caries formation in the secondary caries model of alloxan-induced diabetes. Therefore, Mg-doped ZnO NPs are highly recommended as an antibacterial agent for resin composites to avoid biofilm and subsequent secondary caries formation in high-risk patients.

Effect of Cu Doping on ZnO Nanoparticles as a Photocatalyst for the Removal of Organic Wastewater

Environmental problems with chemical and biological water pollution have become a major concern for society. Providing people with safe and affordable water is a grand challenge of the 21st century. The study investigates the photocatalytic degradation capabilities of hydrothermally prepared pure and Cu-doped ZnO nanoparticles (NPs) for the elimination of dye pollutants. A simple, cost-effective hydrothermal process is employed to synthesize the Cu-doped ZnO NPs. The photocatalytic dye degradation activity of the synthesized Cu-doped ZnO NPs is tested by using methylene blue (MB) dye. In addition, the parameters that affect photodegradation efficiency, such as catalyst concentration, starting potential of hydrogen (pH), and dye concentration, were also assessed. The dye degradation is found to be directly proportional to the irradiation time, as 94% of the MB dye is degraded in 2 hrs. Similarly, the dye degradation shows an inverse relation to the MB dye concentration, as the degradation reduced from 94% to 20% when the MB concentration increases from 5 ppm to 80 ppm. The synthesized cost-effective and environmentally friendly Cu-doped ZnO NPs exhibit improved photocatalytic activity against MB dye and can therefore be employed in wastewater treatment materials.

Preparation and characterization of ternary composite photocatalyst for degradation of oxytetracycline hydrochloride in seawater under visible light

Oxytetracycline hydrochloride is the most widely used veterinary antibiotic in aquaculture. The presence of large amounts of residual antibiotics in aquaculture wastewater harms the ecological environment. In this study, the ternary composite of Zn_0.75Mn_0.75Fe_1.5O₄/ZnFe₂O₄/ZnO (ZMF-ZF-Z) photocatalyst was prepared by the coprecipitation method for degradation of oxytetracycline hydrochloride in marine aquaculture wastewater. The crystal phase, structure, morphology, elemental composition, element content, and optical properties of photogenerated electron-hole pairs of catalyst were characterized by XRD, SEM, EDS, UV-VIS (DRS), PL spectroscopy, and other test methods. The results showed that ZMF-ZF-Z photocatalyst had a larger response range of visible light than pure ZnO, which can absorb more natural light. During the process of the experiment, the photocatalytic effect of Z ZMF-ZF-Z photocatalyst was almost no weakening after 5 times reuse, which means quite good stability of the photocatalyst. Under the visible light irradiation, the degradation rate of oxytetracycline hydrochloride in seawater was 77.11% with ZMF-ZF-Z photocatalyst, which was about 3 times higher than that of pure ZnO, and the photocatalytic activity was significantly improved. This research provides a scientific and effective method for degrading antibiotics in seawater in actual production and life.

Luminescence of SiO2-BaF2:Tb3+, Eu3+ Nano-Glass-Ceramics Made from Sol-Gel Method at Low Temperature

The synthesis and characterization of multicolor light-emitting nanomaterials based on rare earths (RE3+) are of great importance due to their possible use in optoelectronic devices, such as LEDs or displays. In the present work, oxyfluoride glass-ceramics containing BaF2 nanocrystals co-doped with Tb3+, Eu3+ ions were fabricated from amorphous xerogels at 350 °C. The analysis of the thermal behavior of fabricated xerogels was performed using TG/DSC measurements (thermogravimetry (TG), differential scanning calorimetry (DSC)). The crystallization of BaF2 phase at the nanoscale was confirmed by X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM), and the changes in silicate sol-gel host were determined by attenuated total reflectance infrared (ATR-IR) spectroscopy. The luminescent characterization of prepared sol-gel materials was carried out by excitation and emission spectra along with decay analysis from the 5D4 level of Tb3+. As a result, the visible light according to the electronic transitions of Tb3+ (5D4 → 7FJ (J = 6-3)) and Eu3+ (5D0 → 7FJ (J = 0-4)) was recorded. It was also observed that co-doping with Eu3+ caused the shortening in decay times of the 5D4 state from 1.11 ms to 0.88 ms (for xerogels) and from 6.56 ms to 4.06 ms (for glass-ceramics). Thus, based on lifetime values, the Tb3+/Eu3+ energy transfer (ET) efficiencies were estimated to be almost 21% for xerogels and 38% for nano-glass-ceramics. Therefore, such materials could be successfully predisposed for laser technologies, spectral converters, and three-dimensional displays.

Biocidal and biocompatible hybrid nanomaterials from biomolecule chitosan, alginate and ZnO

Biocidal activity and biocompatibility of nanomaterials (NMs) are crucial for healthcare applications. This study aims to develop biocidal hybrid NMs with high inhibition rates to control multidrug-resistant bacterial infection compared to conventional antibiotics. Herein, ZnO, chitosan-ZnO (CZnO) and alginate-ZnO (AZnO) NMs were synthesized via a simple one-pot technique. The one-pot process facilitates the efficiency of a chemical reaction whereby a reactant is subjected to successive chemical reactions in just one step. The resulted NMs bio-physicochemical features were analyzed using various analytical methods. The bactericidal and bacteriostatic mechanism of NMs strongly depends on the production of reactive oxygen species in NMs, due to their size, large surface areas, oxygen vacancies, ion release, and diffusion ability. The antibacterial potential of the NMs was tested against methicillin-resistant Staphylococcus aureus. The inhibition zone disclosed that the AZnO possessed an excellent antibacterial activity compared to ZnO and CZnO. Furthermore, toxicity studies revealed that the AZnO demonstrated low toxicity to the HepG2 cell lines. These results confirmed that the AZnO hybrid nanomaterials are promising futuristic biocidal agents suitable for the clinical and healthcare industries.

Synthesis, Drug Release, and Antibacterial Properties of Novel Dendritic CHX-SrCl2 and CHX-ZnCl2 Particles

This work demonstrated for the first time the synthesis of novel chlorhexidine particles containing strontium and zinc, to provide an effective, affordable, and safe intervention in the treatment of recurrent infections found in Medicine and Dentistry. The CHX-SrCl₂ and CHX-ZnCl₂ particles were synthesized by co-precipitation of chlorhexidine diacetate (CHXD) and zinc chloride or strontium chloride, where particle size was manipulated by controlling processing time and temperature. The CHX-ZnCl₂ and CHX-SrCl₂ particles were characterized using SEM, FTIR, and XRD. UV-Vis using artificial saliva (pH 4 and pH 7) was used to measure the drug release and ICP-OES ion release. The antibacterial properties were examined against P. gingivalis, A. actinomycetemcomitans, and F. nucleatum subsp. Polymorphum, and cytotoxicity was evaluated using mouse fibroblast L929 cells. The novel particles were as safe as commercial CHXD, with antibacterial activity against a range of oral pathogens. UV-Vis results run in artificial saliva (pH 4 and pH 7) indicated a higher release rate in acidic rather than neutral conditions. The CHX-ZnCl₂ particles provided the functionality of a smart Zinc and CHX release, with respect to environmental pH, allowing responsive antibacterial applications in the field of medicine and dentistry.

Electrospun Nanosystems Based on PHBV and ZnO for Ecological Food Packaging

The electrospun nanosystems containing poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and 1 wt% Fe doped ZnO nanoparticles (NPs) (with the content of dopant in the range of 0–1 wt% Fe) deposited onto polylactic acid (PLA) film were prepared for food packaging application. They were investigated by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), antimicrobial analysis, and X-ray photoelectron spectrometry (XPS) techniques. Migration studies conducted in acetic acid 3% (wt/wt) and ethanol 10% (v/v) food simulants as well as by the use of treated ashes with 3% HNO₃ solution reveal that the migration of Zn and Fe falls into the specific limits imposed by the legislation in force. Results indicated that the PLA/PHBV/ZnO:Fex electrospun nanosystems exhibit excellent antibacterial activity against the Pseudomonas aeruginosa (ATCC-27853) due to the generation of a larger amount of perhydroxyl (˙OOH) radicals as assessed using electron paramagnetic resonance (EPR) spectroscopy coupled with a spin trapping method.

Enhanced Optical and Antibacterial Activity of Hydrothermally Synthesized Cobalt-Doped Zinc Oxide Cylindrical Microcrystals

Cobalt (Co) doped zinc oxide (ZnO) microcrystals (MCs) are prepared by using the hydrothermal method from the precursor's mixture of zinc chloride (ZnCl2), cobalt-II chloride hexahydrate (CoCl2·6H2O), and potassium hydroxide (KOH). The smooth round cylindrical morphologies of the synthesized microcrystals of Co-doped ZnO show an increase in absorption with the cobalt doping. The antibacterial activity of the as-obtained Co-doped ZnO-MCs was tested against the bacterial strains of gram-negative (Escherichia coli, Klebsiella pneumonia) and gram-positive bacteria (Staphylococcus aureus, Streptococcus pyogenes) via the agar well diffusion method. The zones of inhibition (ZOI) for Co-doped ZnO-MCs against E. coli and K. pneumoniae were found to be 17 and 19 mm, and 15 and 16 mm against S. Aureus and S. pyogenes, respectively. The prepared Co-doped ZnO-MCs were thus established as a probable antibacterial agent against gram-negative bacterial strains.

Biocidal chitosan-magnesium oxide nanoparticles via a green precipitation process

In the present scenario, the development of eco-friendly multifunctional biocidal substances with low cost and high efficiency, has become the center of focus. This study is, focused on the synthesis of magnesium oxide (MgO) and chitosan-modified magnesium oxide (CMgO) nanoparticles (NPs), via a green precipitation process. In this process, leaves extract of Plumbago zeylanica L was, used as a nucleating agent. The MgO and CMgO NPs exhibit face-centered cubic structures, as confirmed by XRD studies. Morphologically, the FESEM and TEM images showed that the MgO and CMgO NPs were spherical, with an average particle size of ~40±2 and ~37±2 nm, respectively. EDX spectra were used to identify the elemental compositions of the nanoparticles. By using FTIR spectra, the Mg-O stretching frequency of MgO and CMgO NPs were observed at 431 and 435 cm^-1, respectively. The photoluminescence (PL) spectra of MgO and CMgO NPs, revealed oxygen vacancies at 499 nm and 519 nm, respectively, due to the active radicals generated, which were responsible for their biocidal activities. The toxicity effects of the nanoparticles developed, on cell viability (antibacterial and anticancer), were measured on the MCF-7 cell line and six different types of gram-negative bacteria. The antibacterial activities of the nanoparticles on: Klebsiella pneumoniae, Escherichia coli, Shigella dysenteriae, Pseudomonas aeruginosa, Proteus vulgaris and Vibrio cholerae bacteria, were studied with the well diffusion method. The MgO and CMgO NPs were tested on breast cancer cell line (MCF-7) via an MTT assay and it proved that CMgO NPs possess higher anticancer properties than MgO NPs. Overall, CMgO NPs showed a higher amount of cytotoxicity for both the bacterial and cancer cells when compared to the MgO NPs. Toxicity studies of fibroblast L929 cells revealed that the CMgO NPs were less harmful to the healthy cells when compared to the MgO NPs. These results suggest that biopolymer chitosan-modified MgO NPs can be used for healthcare industrial applications in order to improve human health conditions.

Effect of Mg doping on ZnO fabricated using aqueous leaf extract of Ziziphus mauritiana Lam. for antioxidant and antibacterial studies

Aqueous leaf extract of Ziziphus mauritiana Lam. was successfully used to synthesize zinc oxide (ZnO) and magnesium-doped ZnO (Mg-doped ZnO) particles and acted as capping and stabilizing agent. UV-Vis diffuse reflectance spectra showed that optical band gap energy of ZnO has narrowed from 3.11 to 3.08 eV and 3.03 eV when doped with 1% Mg and 5% Mg, respectively. Powder X-ray diffraction and X-ray photoelectron spectroscopy studies confirmed the purity and crystalline nature of the synthesized materials. FT-IR spectroscopy revealed the presence of phytochemicals coated on the surface of synthesized materials. The synthesized materials were found to effectively scavenge DPPH radicals in the presence of visible light in comparison to the dark. The antibacterial properties of the synthesized materials were evaluated against Staphylococcus aureus and Escherichia coli. The obtained results revealed that Staphylococcus aureus seemed to be more sensitive to the green synthesized ZnO and Mg-doped ZnO than Escherichia coli.

An insight into the mechanism of antibacterial activity by magnesium oxide nanoparticles

The exact mechanism behind the antibacterial efficacy of nanoparticles has remained unexplored to date. This study aims to shed light the mechanism adopted using magnesium oxide nanoparticles prepared in ethyl alcohol against gram-negative and gram-positive bacterial cells, and the generation of reactive oxygen species (ROS) is proposed to be the dominant mechanism. This paradigm is supported by the quantification of the hydroxyl radical and superoxide anions produced in the nanoparticle treated and untreated bacterial solutions, and by the reduction of the antibacterial efficiency after the addition of a radical scavenger. The production of free Mg2+ ions from the nanoparticle is supposed to be the causative agent behind this uncontrolled ROS generation, resulting in excessive oxidative stress, which the antioxidants of the bacterial cells are unable to nullify, leading to cell damage. The amount of proteins, carbohydrates and lipids leaked due to the distortion of the cellular membrane is also quantified, and it is observed that their leakage trend varies on the structure of the bacterial cell. FESEM images taken at certain time intervals show the gradual internalization of the nanoparticles, and increasing rupture of bacterial cell membranes, leading to cell necrosis.

Effects of zinc oxide and calcium-doped zinc oxide nanocrystals on cytotoxicity and reactive oxygen species production in different cell culture models

Objectives

This study aimed to synthesize nanocrystals (NCs) of zinc oxide (ZnO) and calcium ion (Ca²⁺)-doped ZnO with different percentages of calcium oxide (CaO), to evaluate cytotoxicity and to assess the effects of the most promising NCs on cytotoxicity depending on lipopolysaccharide (LPS) stimulation.

Materials and Methods

Nanomaterials were synthesized (ZnO and ZnO:xCa, x = 0.7; 1.0; 5.0; 9.0) and characterized using X-ray diffractometry, scanning electron microscopy, and methylene blue degradation. SAOS-2 and RAW 264.7 were treated with NCs, and evaluated for viability using the MTT assay. NCs with lower cytotoxicity were maintained in contact with LPS-stimulated (+LPS) and nonstimulated (−LPS) human dental pulp cells (hDPCs). Cell viability, nitric oxide (NO), and reactive oxygen species (ROS) production were evaluated. Cells kept in culture medium or LPS served as negative and positive controls, respectively. One-way analysis of variance and the Dunnett test (α = 0.05) were used for statistical testing.

Results

ZnO:0.7Ca and ZnO:1.0Ca at 10 µg/mL were not cytotoxic to SAOS-2 and RAW 264.7. +LPS and −LPS hDPCs treated with ZnO, ZnO:0.7Ca, and ZnO:1.0Ca presented similar NO production to negative control (p > 0.05) and lower production compared to positive control (p < 0.05). All NCs showed reduced ROS production compared with the positive control group both in +LPS and −LPS cells (p < 0.05).

Conclusions

NCs were successfully synthesized. ZnO, ZnO:0.7Ca and ZnO:1.0Ca presented the highest percentages of cell viability, decreased ROS and NO production in +LPS cells, and maintenance of NO production at basal levels.

Microwave-Assisted Synthesis of Hollow Microspheres with Multicomponent Nanocores for Heavy-Metal Removal and Magnetic Sensing

The primary advantage of a hollow structure is the likelihood of introducing diverse components in a single particle to achieve multiple missions. Herein, hollow microspheres with multicomponent nanocores (HMMNs) have been prepared based on a template-free strategy via a microwave-assisted hydrothermal treatment of Chlorella. The resulting HMMNs retain the near-spherical hollow morphology and functional groups of the cell wall of Chlorella, obviating the need for templates and chemical modification. The elements (iron, cobalt, calcium, magnesium, chlorine, and phosphorus) naturally present within the Chlorella cells react to form hydroxyapatite/chlorapatite and magnetic nanocores without the need for exogenous chemical reagents. The performances of HMMNs for cadmium ion (Cd²⁺) removal and antibiotic detection are explored. HMMNs exhibit relatively high adsorbance of Cd²⁺ (1035.8 mmol/kg) and can be easily recovered by application of an external magnetic field. Ion exchange with Ca²⁺ and Mg²⁺ is shown to be the main mechanism of Cd²⁺ elimination. In addition, HMMNs are a suitable carrier for the construction of a magnetic immunosensor, as demonstrated by the successful development of such an immunosensor with acceptable analytical performance for the detection of neomycin in milk samples. The versatile applications of HMMNs result from their multicomponent nanocores, hollow structure, and the functional groups on their shell. This work not only offers a simple and eco-friendly strategy for the fabrication of novel HMMNs but also provides a valuable advanced material for contaminant detection and heavy-metal removal.

Bi-doping improves the magnetic properties of zinc oxide nanowires

Room-temperature ferromagnetism in the large and direct bandgap diluted magnetic semiconductor zinc oxide (ZnO) is attributed to the intrinsic defects and p-orbital–p-orbital (p–p) coupling interaction. However, due to oxidation, the ferromagnetism induced by defects is unstable. In the present work, the solution process synthesis route was utilized to grow pristine and bismuth-doped, highly crystalline ZnO nanowire (ZnO NW)-based samples. The FE-SEM images showed that the grown ZnO NWs have a preferred orientation along the c-axis in the (001) direction due to the anisotropic crystal nature of ZnO. X-ray photoelectron spectroscopy (XPS) confirmed the presence of Bi, and at a higher doping content, the bismuth oxide phase appeared. The XRD patterns showed the wurtzite crystal structure, and the large intensity of the (002) peak suggests that most of the reflection was from the top hexagonal face of the NWs, and thus, the wires are predominantly aligned along the c-axis. The TEM analysis further confirmed the crystal growth direction along the (001) direction. The UV-Visible absorption and PL measurements also showed a decrease in the bandgap with an increase in doping concentration, which may be associated with the sp–d exchange interaction between the localized d-electrons and band electrons of the Bi ions. Bi-doping tended to increase the PL intensity in the visible region. The magnetic properties measured by SQUID at 4 and 300 K showed ferromagnetic behaviour for both the pristine and Bi-doped samples. However, the saturation magnetization for the Bi-doped samples was higher compared to that of the pristine ZnO samples until the threshold doping value. The obtained results demonstrated that Bi-doping can be used to tune both the optical and magnetic properties of ZnO NWs, hence paving the way for future spintronics and spin-polarized optoelectronics applications.

Room-temperature ferromagnetism in the large and direct bandgap diluted magnetic semiconductor zinc oxide (ZnO) is attributed to the intrinsic defects and p-orbital–p-orbital (p–p) coupling interaction.

Nano-Structured Dilute Magnetic Semiconductors for Efficient Spintronics at Room Temperature

In recent years, many efforts have been made to develop advanced metal oxide semiconductor nanomaterials with exotic magnetic properties for modern applications w.r.t traditional analogues. Dilute magnetic semiconductor oxides (DMSOs) are promising candidates for superior control over the charge and spin degrees of freedom. DMSOs are transparent, wide band gap materials with induced ferromagnetism in doping, with a minor percentage of magnetic 3d cation to create a long-range antiferromagnetic order. Although significant efforts have been carried out to achieve DMSO with ferromagnetic properties above room temperature, it is a great challenge that still exists. However, TiO2, SnO2, ZnO and In2O3 with wide band gaps of 3.2, 3.6, 3.2 and 2.92 eV, respectively, can host a broad range of dopants to generate various compositions. Interestingly, a reduction in the size of these binary oxides can induce ferromagnetism, even at room temperature, due to the grain boundary, presence of defects and oxygen vacancies. The present review provides a panorama of the structural analysis and magnetic properties of DMSOs based on binary metal oxides nanomaterials with various ferromagnetic or paramagnetic dopants, e.g., Co, V, Fe and Ni, which exhibit enhanced ferromagnetic behaviors at room temperature.

Influence of Dopant Nature on Biological Properties of ZnO Thin-Film Coatings on Ti Alloy Substrate

In this paper, ZnO and Co2+/Mg2+-doped ZnO thin films on TiAlV alloy substrates were obtained. The films were deposited by spin coating of sol-gel precursor solutions and thermally treated at 600 °C for 2 h, in air and slow cooled. The doping ions concentration was 1.0 mol%. The study's aim was to obtain implantable metallic materials with improved biocompatibility and antibacterial qualities. The characteristics of the thin films were assessed from the point of view of microstructure, morphology, wetting properties, antibacterial activity and biological response in the presence of amniotic fluid stem cells (AFSC). The results proved that all deposited samples were nanostructured, suggesting a very good antibacterial effect and proving to be suitable supports for cellular adhesion and proliferation. All properties also depended on the doping ion nature.

Reddish-Orange Luminescence from BaF2:Eu3+ Fluoride Nanocrystals Dispersed in Sol-Gel Materials

Nanocrystalline transparent BaF2:Eu3+ glass-ceramic materials emitting reddish-orange light were fabricated using a low-temperature sol-gel method. Several experimental techniques were used to verify structural transformation from precursor xerogels to sol-gel glass-ceramic materials containing fluoride nanocrystals. Thermal degradation of xerogels was analyzed by thermogravimetric analysis (TG) and differential scanning calorimetry method (DSC). The presence of BaF2 nanocrystals dispersed in sol-gel materials was confirmed by the X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM). In order to detect structural changes in silica network during annealing process, the infrared spectroscopy (IR-ATR) was carried out. In particular, luminescence spectra of Eu3+ and their decays were examined in detail. Some spectroscopic parameters of Eu3+ ions in glass-ceramics containing BaF2 nanocrystals were determined and compared to the values obtained for precursor xerogels. It was observed, that the intensities of two main red and orange emission bands corresponding to the 5D0→7F2 electric-dipole transition (ED) and the 5D0→7F1 magnetic-dipole (MD) transition are changed significantly during transformation from xerogels to nanocrystalline BaF2:Eu3+ glass-ceramic materials. The luminescence decay analysis clearly indicates that the measured lifetime 5D0 (Eu3+) considerably enhanced in nanocrystalline BaF2:Eu3+ glass-ceramic materials compared to precursor xerogels. The evident changes in luminescence spectra and their decays suggest the successful migration of Eu3+ ions from amorphous silica network to low-phonon BaF2 nanocrystals.

Rubidium-containing mesoporous bioactive glass scaffolds support angiogenesis, osteogenesis and antibacterial activity

In this study, rubidium-containing mesoporous bioglass (Rb-MBG) scaffolds were formed with the investigation of the influence of Rb addition on angiogenic and osteogenic differentiation abilities of hBMSC. The phase composition, microstructure, pore size distribution, ion release, biological activity, drug loading rate, and release rate of Rb-MBG were characterized. The proliferation and differentiation of hBMSC, the markers of bone formation (ALP, COL-1) and angiogenesis (VEGF, HIF-1α), and wnt/β-catenin related-signaling pathway gene were studied by cell culture. Rb-MBG loaded with antibacterial agents enoxacin (ENX), coliforms and Staphylococcus aureus were cultured together to study the antibacterial effects. The results indicate that the samples have a 350-550 μm large pore structure and 4.5-5.5 nm mesoporous size. Adding Rb can increase the activity of ALP, the secretion of VEGF and COLI, and the expression of HIF-1α of hBMSCs. Rb containing MBG is likely to enhance the proliferation and differentiation of hBMSCs through the influence of Wnt/ß-catenin signal path. Rb-MBG scaffold can load effectively and release Rb ions and ENX continuously to damage the bacterial cell membrane with the synergistic effect, and therefore achieve antibacterial results. In conclusion, adding Rb to MBG supports angiogenesis and osteogenesis of hBMSCs, as well as antibacterial activity.

Ionic liquid - A greener templating agent with Justicia adhatoda plant extract assisted green synthesis of morphologically improved Ag-Au/ZnO nanostructure and it's antibacterial and anticancer activities

Metal and metal oxide nanoparticles (NPs) possess significant properties that are promising materials for biological applications. In this research work, we prepared ionic liquid assisted Ag-Au/ZnO NPs, using J.adhatoda leaves extract by hydrothermal method. Ionic liquids performed as a stabilizing and templating agent to improve the surface morphology of the synthesized Ag and Au doped ZnO NPs. The prepared ZnO, Ag-doped ZnO, Au doped ZnO, and AgAu doped ZnO NPs exhibit the average crystalline size of 36, 34, 32, and 25 nm and their band gap energy values are 3.36, 3.29, 3.17, and 2.98 eV respectively. The XRD and UV-DRS result shows that after doping of Au and Ag the ZnO crystalline size and band gap energy was decreased, which leads to enhanced the biomedical (antibacterial and anticancer) properties of AgAu doped ZnO NPs. The Raman active mode of A₁ (LO) and A₁ (TO) showed that the formation of lattice defects due to the Ag and Au doping in the ZnO crystalline plane to improve the Ag-Au/ZnO properties. SEM and TEM images revealed that the prepared AgAu doped ZnO NPs exhibits nano stick shape with particle size range from 20 to 25 nm. The EDX spectrum and elemental mapping results confirmed that Ag and Au atoms are doped and spread over the ZnO NPs. The corresponding SAED pattern also confirms the crystallinity of Ag-Au/ZnO NPs. Furthermore, the synthesized Ag-Au/ZnO NPs has been explored for its antibacterial and anticancer activities. It shows good antibacterial activity against E.coli and S.aureus bacteria. Additionally, the Ag-Au/ZnO NPs show excellent anticancer activity against the HeLa cancer cells. The excellent antibacterial and anticancer results prove that the bi-metal (Ag and Au) doping can enhance the biomedical properties of ZnO NPs. It will be a promising material in the biomedical field.

Impact of l-Arginine and l-Histidine on the structural, optical and antibacterial properties of Mg doped ZnO nanoparticles tested against extended-spectrum beta-lactamases (ESBLs) producing Escherichia coli

Magnesium doped Zinc oxide nanoparticles (Mg:ZnO NPs) were synthesized by co-precipitation method. The synthesized Mg:ZnO NPs exhibited hexagonal wurtzite structure, which was confirmed by X-ray diffraction results. After structural confirmation of Mg doped ZnO NPs, base amino acids like l-Arginine and l-Histidine were separately incorporated with the Mg: ZnO NPs. l-Arginine added Mg:ZnO (Mg:ZnO:LA) and l-Histidine added Mg:ZnO (Mg:ZnO: LH) NPs retained the same wurtzite hexagonal structure and average crystallite sizes of Mg: ZnO:LA and Mg: ZnO:LH NPs were found to be 25 nm and 20 nm respectively. The sizes of Mg:ZnO:LH and Mg: ZnO: LA NPs decreased as compared to that of the Mg doped ZnO NPs. From the FT-IR spectra, the ZnO stretching frequencies were observed at 516, 517 and 518 cm^-1 for Mg:ZnO, Mg:ZnO: LA and Mg: ZnO:LH NPs respectively. From the FESEM images, the morphologies of ZnO:Mg and ZnO:Mg:LA NPs were spherical and the Mg: ZnO: LH NPs formed nano-flakes structure. From the EDAX study, the amount of elements incorporated in the samples was determined. The photoluminescence measurements revealed the existence of zinc vacancies, oxygen vacancies and surface defects of the samples. Antibacterial activity of the amino acid added Mg doped ZnO NPs was studied against extended-spectrum beta-lactamases (ESBLs) producing Escherichia coli (E. coli).The Minimal Inhibitory Concentration (MIC) of the LH added ZnO:Mg NPs was found to be 1000 μg/ml for which the growth of E. coli completely inhibited. l-Histidine added Mg doped ZnO NPs showed the highest antibacterial activity as compared to that of the Mg:ZnO NPs and ZnO:Mg:LA NPs.

Effect of cobalt doping on microstructures and dielectric properties of ZnO

Pure and cobalt-doped ZnO nanoparticles (2.5, 5, 7.5, and 10 atom % Co) are synthesized by sol–gel method. The as-synthesized nanoparticles are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FE-SEM) analysis. The nanoparticles of 0, 2.5, and 5 atom % Co-doped ZnO exhibited hexagonal wurtzite structure and have no other phases. Moreover, the (101) diffraction peaks position of Co-doped ZnO shift toward a smaller value of diffraction angle compared with pure ZnO powders. The results confirm that Co ions were well incorporated into ZnO crystal lattice. Simultaneously, Co doping also inhibited the growth of particles, and the crystallite size decreased from 43.11 nm to 36.63 nm with the increase in doping concentration from 0 to 10 atom %. The values of the optical band gap of all Co-doped ZnO nanoparticles gradually decreased from 3.09 eV to 2.66 eV with increasing Co content. Particular, the dielectric constant of all Co-doped ZnO ceramics gradually increased from 1.62 × 103 to 20.52 × 103, and the dielectric loss decreased from 2.36 to 1.28 when Co content increased from 0 to 10 atom %.

Unraveling the effect of Gd doping on the structural, optical, and magnetic properties of ZnO based diluted magnetic semiconductor nanorods

The structural, magnetic, and optical properties of the pristine and Gd-doped ZnO nanorods (NRs), prepared by facile thermal decomposition, have been studied using a combination of experimental and density functional theory (DFT) with Hubbard U correction approaches. The XRD patterns demonstrate the single-phase wurtzite structure of the pristine and doped ZnO. The rod-like shape of the nanoparticles has been examined by FESEM and TEM techniques. Elemental compositions of the pure and doped samples were identified by EDX measurement. Due to the Burstein–Moss shift, the optical band gaps of the doped samples have been widened compared to pristine ZnO. The PL spectra show the presence of complex defects. Room temperature magnetic properties have been measured using VSM and revealed the coexistence of paramagnetic and weak ferromagnetic ordering in Gd³⁺ doped ZnO-NRs. The magnetic moment was increased upon addition of more Gd ions into the ZnO host lattice. The DFT+U calculations confirm that the presence of vacancy-complexes has a significant effect on the structural, electronic, and magnetic properties of a pristine ZnO system.

Gd doped ZnO nanorods.