Antibacterial and Photocatalytic Properties of ZnO Nanoparticles Obtained from Chemical versus Saponaria officinalis Extract-Mediated Synthesis

In the present work, the properties of ZnO nanoparticles obtained using an eco-friendly synthesis (biomediated methods in microwave irradiation) were studied. Saponaria officinalis extracts were used as both reducing and capping agents in the green nanochemistry synthesis of ZnO. Inorganic zinc oxide nanopowders were successfully prepared by a modified hydrothermal method and plant extract-mediated method. The influence of microwave irradiation was studied in both cases. The size, composition, crystallinity and morphology of inorganic nanoparticles (NPs) were investigated using dynamic light scattering (DLS), powder X-ray diffraction (XRD), SEM-EDX microscopy. Tunings of the nanochemistry reaction conditions (Zn precursor, structuring agent), ZnO NPs with various shapes were obtained, from quasi-spherical to flower-like. The optical properties and photocatalytic activity (degradation of methylene blue as model compound) were also investigated. ZnO nanopowders’ antibacterial activity was tested against Gram-positive and Gram-negative bacterial strains to evidence the influence of the vegetal extract-mediated synthesis on the biological activity.     

ZnO纳米粒子多相催化n-C7H16-SO2气相光化学反应的研究

利用自制的ZnO纳米粒子和商品的ZnO粒子，研究了ZnO粒子多相催化n-C6H16- SO2的气相光化学反应。利用气相色谱－质谱联用仪（GC／MS）和气相色谱仪（GC ）对反应物n-C6H16和SO2以及主要气相产物3－庚酮进行了定量分析，考察了不同 条件下它们的降解和产生趋势，初步探讨了氧气和水蒸气对ZnO粒子多相催化n- C7H16-SO2气相光化学反应的影响，并对反应的一些现象作了描述及相应的说明。 结果表明，无论有无氧化存在，ZnO粒子均能够对n-C7H16-SO2的气相光化学反应起 一定的催化作用，但是有氧气的催化活性比无氧气的高。这可能说明了ZnO的光催 化作用主要与生成的活性氧物种（O^*)有关，同时光致空穴（h^+）也能够直接引 发氧化反应；虽然ZnO纳米粒子的光催化活性随着焙烧温度的升高而降低，但是均 比商品的高。而在模拟大气的条件下，ZnO纳米粒子对n-C7H16SO2的气相光化学反 应有很大的影响，大大地促进了n-C7H16和SO2的降解，这说明ZnO纳米粒子的存在 对大气中SO2－烃的气相光化学反应的影响是不容忽视的。此外，对ZnO粒子多相催 化n-C7H16-SO2气相光化学反应的机理进行了探讨。     

Broad spectrum antibacterial zinc oxide-reduced graphene oxide nanocomposite for water depollution

Antimicrobial-resistance (AMR) is a global health challenge arising from the evolution of bacteria, viruses, fungi, and parasites, such that pathogenic microorganisms no longer respond to classical therapies. AMR and the rise of so-called ‘superbugs’ requires innovative nanomaterials and biostatic strategies. Here we report a broad spectrum, antimicrobial nanomaterial integrating light-responsive ZnO nanoparticles (NP) and reduced graphene oxide (rGO) into a heterojunction semiconductor nanocomposite for water depollution. Simultaneous chemical reduction of Zn sulphate and GO sheets yields a low concentration (0.5 mol%) of 10 nm ZnO nanoparticles decorating fragmented rGO nanosheets, with a total surface area of 12 m²/g and optical band gap of 1.6 eV. Antimicrobial performance of the ZnO-rGO nanocomposite was evaluated against methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli 0157:H7 and Salmonella typhimurium bacteria, which are prevalent in contaminated aquatic systems; antimicrobial efficacy against these organisms was 96%, 97%, and 73%, respectively, for a loading of 2 mg/mL, evidencing a strong synergy compared with pure ZnO or rGO components. ZnO-rGO was also an effective photocatalyst for the aqueous degradation of Malachite Green dye, suggesting that its mode of antibacterial action reflects the production of reactive oxygen species under ambient illumination.     

Preparation,characterization, and antibacterial activity of organo-sepiolite/chitosan/silver bionanocomposites

Bionanocomposites with different loadings of silver (Ag) were prepared via synthesis of Ag nanoparticles (AgNPs) using the wet chemical reduction method in the lamellar space layer of the organo-sepiolite/chitosan (O-SEP/CS). The prepared O-SEP/CS/Ag bionanocomposites were characterized using various analysis methods for their structure, morphology, and optical properties. The characteristic absorption bands from the UV–visible absorption spectrum confirmed the formation of AgNPs. The antibacterial activities of O-SEP/CS/Ag bionanocomposites were investigated against gram-positive and gram-negative bacteria using the disc diffusion method. The results suggest that O-SEP/CS/Ag bionanocomposites can be useful in wide range of bio-medical applications because of high antibacterial activity.     

Synthesis, characterization and study of photocatalytic activity of surface modified ZnO nanoparticles by PEG capping

Nanoparticles of bare and PEG (Polyethylene glycol) capped zinc oxide (ZnO) were synthesized by precipitation method. The photocatalytic activity of bare and modified ZnO nanoparticles was studied by monitoring the degradation of Rhodamine B (RhB). The results show that PEG capped ZnO nanoparticles has reduced photocatalytic activity than the bare ZnO nanoparticles. The reduction in the chemical oxygen demand (COD) and total organic carbon (TOC) results also revealed the reduced photocatalytic activity of PEG capped ZnO. The UV-shielding property was evaluated by measuring the transmittance which shows that both bare and PEG capped ZnO nanoparticles possess good UV-shielding ability.     

Microwave-assisted synthesis of water-soluble styrylpyridine dye-capped zinc oxide nanoparticles for antibacterial applications

ZnO nanoparticles were successfully synthesized using a microwave method, whose surface was modified with {4-[(E)-2-(furan-2-yl)ethenyl]pyridin-1-ium-1-yl}acetate as a capping agent (1 and 3%). Their structural properties were investigated using FTIR, XRD, SEM, EDS, and UV–visible spectroscopy. XRD confirmed the Wurtzite structure for all compounds, a size of 30.6 nm for uncapped and 22.9 nm for 3% dye-capped nanoparticles were calculated from Scherer's equation. Hexagonal wurtzite shape of nanoparticles can be clearly seen in the SEM images. The DFT calculations were carried out using quantum espresso. These dye-capped ZnO nanoparticles were proved to be potential antibacterial agents, the minimum concentrations of dye-capped ZnO nanoparticles that inhibit the growth of bacteria are 1.5 mg/mL for Escherichia coli and 0.78 mg/mL for Bacillus subtilis, which are much lower than those of uncapped ZnO. The bioactivity data suggest these organic–inorganic hybrid nanoparticles emerged as a new class of antibacterial agents.     

Pd/ZnO和Ag/ZnO复合纳米粒子的制备、表征及光催化活性

 用焙烧前驱物碱式碳酸锌的方法制备了ZnO纳米粒子，采用光还原沉积贵金属的方法制备了Pd／ZnO和Ag／ZnO复合纳米粒子，并利用ICP，XRD，TEM和XPS等测试技术对样品进行了表征，初步探讨了贵金属在ZnO纳米粒子表面形成原子簇的原因．以光催化氧化气相正庚烷为模型反应，考察了样品的光催化活性以及贵金属沉积量对催化剂活性的影响．结果表明：沉积适量的贵金属，ZnO纳米粒子光催化剂的活性大幅度提高．同时，深入探讨了表面沉积贵金属的ZnO纳米粒子光催化剂活性有所提高的内在原因．     

Controlled reduction of the deleterious effects of photocatalytic activity of ZnO nanoparticles by PVA capping

Nanoparticles of uncapped and PVA (poly vinyl alcohol) capped zinc oxide were synthesized by precipitation method. The synthesized ZnO nanoparticles were characterized by fourier transform infrared spectroscopy, X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and thermogravimetric-differential thermal analysis. The photocatalytic activity of bare and modified ZnO nanoparticles was studied by monitoring the degradation of Rhodamine B. The results show that PVA capped ZnO nanoparticles has reduced photocatalytic activity than the bare ZnO nanoparticles. The reduction in the chemical oxygen demand and total organic carbon results also revealed the reduced photocatalytic activity of PVA capped ZnO. The UV-shielding property was evaluated by measuring the transmittance which shows that both bare and PVA capped ZnO nanoparticles possess good UV-shielding ability.     

Zn or O? An Atomic Level Comparison on Antibacterial Activities of Zinc Oxides

For the first time, the influence of different types of atoms (Zn and O) on the antibacterial activities of nanosized ZnO was quantitatively evaluated with the aid of a 3D‐printing‐manufactured evaluation system. Two different outermost atomic layers were manufactured separately by using an ALD (atomic layer deposition) method. Interestingly, we found that each outermost atomic layer exhibited certain differences against gram‐positive or gram‐negative bacterial species. Zinc atoms as outermost layer (ZnO?Zn) showed a more pronounced antibacterial effect towards gram‐negative E. coli (Escherichia coli), whereas oxygen atoms (ZnO?O) showed a stronger antibacterial activity against gram‐positive S. aureus (Staphylococcus aureus). A possible antibacterial mechanism has been comprehensively discussed from different perspectives, including Zn²⁺ concentrations, oxygen vacancies, photocatalytic activities and the DNA structural characteristics of different bacterial species.     

Enhanced photocatalytic activity of ZnO nanoparticles by surface modification with KF using thermal shock method

ZnO nanoparticles were modified with KF using thermal shock method at various temperatures in order to improve the photocatalytic activity of ZnO under both UVA and visible light irradiation. The influences of KF-modification on the crystal structure, morphology, UV–visible absorption, specific surface area as well as surface structure of ZnO were respectively characterized by XRD, FE-SEM, UV–Visible diffuse reflectance, N₂ adsorption and XPS spectroscopy. The photocatalytic activity was evaluated via the degradation of methylene blue under UVA irradiation. According to the results, the thermal shock process with KF did not modify the structure, the particle size and the optical properties of ZnO nanoparticles but successfully increase their UVA and visible light induced photocatalytic activity. This enhancement of activity may be attributed to the increase of surface hydroxyl groups and zinc vacancies of modified ZnO samples.     

Green synthesis,characterization, and biological activities of saffron leaf extract-mediated zinc oxide nanoparticles: A sustainable approach to reuse an agricultural waste

To increase the profitability and sustainability of agricultural waste, a facile green approach was established to synthesize zinc oxide nanoparticles (ZnO NPs) using saffron leaf extract as a reducing and stabilizing agent. Structural characteristics of NPs were investigated by X-ray diffraction (XRD), Fourier-transform infrared (FTIR), field emission scanning electron microscopy (FESEM), and UV–Visible (UV–Vis) spectroscopy. Characterization results revealed that ZnO NPs is highly crystalline with a hexagonal wurtzite structure and spherical particles with diameter less than 50 nm, as confirmed by XRD and FESEM techniques. UV–Vis absorption spectra depicted an absorption peak at 370 nm, which confirms the formation of ZnO NPs. FTIR spectral analysis confirmed the presence of functional groups and metal oxygen groups. The biological activities of ZnO NPs were also investigated. The antibacterial effect of ZnO NPs was investigated against selected food pathogens (Salmonella Typhimurium, Listeria monocytogenes, and Enterococcus faecalis). The study results prove that the green synthesized ZnO NPs show enhanced antibacterial activity against S. Typhimurium when compared with other strains. A dose-dependent free radical scavenging activity was observed for ZnO NPs in both 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) and fluorescence recovery after photobleaching (FRAP) assays. The ZnO NPs were evaluated for their photocatalytic activity during the degradation of methylene blue (MB) dye in aqueous solutions. The maximum removal of MB achieved was 64% with an initial ZnO NP concentration of 12 mg/mL under UV light. The present study revealed that the agricultural waste (saffron leaf) provides a simple and eco-friendly option to sustainably synthesize ZnO NPs for use as a photocatalyst. In addition, this is the first report on saffron leaf-mediated synthesis of ZnO NPs.     

Effect of Mg doping on morphology,photocatalytic activity and related biological properties of Zn1−xMgxO nanoparticles

The objective of this study is to synthesize ZnO and Mg doped ZnO (Zn_1−xMg_xO) nanoparticles via the sol-gel method, and characterize their structures and to investigate their biological properties such as antibacterial activity and hemolytic potential.Nanoparticles (NPs) were synthesized by the sol-gel method using zinc acetate dihydrate (Zn(CH₃COO)₂.2H₂O) and magnesium acetate tetrahydrate (Mg(CH₃COO)₂.4H₂O) as precursors. Methanol and monoethanolamine were used as solvent and sol stabilizer, respectively. Structural and morphological characterizations of Zn_1−xMg_xO nanoparticles were studied by using XRD and SEM-EDX, respectively. Photocatalytic activities of ZnO and selected Mg-doped ZnO (Zn_1−xMg_xO) nanoparticles were investigated by degradation of methylene blue (MeB). Results indicated that Mg doping (both 10% and 30%) to the ZnO nanoparticles enhanced the photocatalytic activity and a little amount of Zn0.90 Mg0.10 O photocatalyst (1.0 mg/mL) degraded MeB with 99% efficiency after 24 h of irradiation under ambient visible light. Antibacterial activity of nanoparticles versus Escherichia coli ( E. coli ) was determined by the standard plate count method. Hemolytic activities of the NPs were studied by hemolysis tests using human erythrocytes. XRD data proved that the average particle size of nanoparticles was around 30 nm. Moreover, the XRD results indicatedthat the patterns of Mg doped ZnO nanoparticles related to ZnO hexagonal wurtzite structure had no secondary phase for x ≤ 0.2 concentration. For 0 ≤ x ≤ 0.02, NPs showed a concentration dependent antibacterial activity against E. coli . While Zn_0.90Mg_0.10 O totally inhibited the growth of E. coli , upper and lower dopant concentrations did not show antibacterial activity.     

Probing the Reactivity of ZnO and Au/ZnO Nanoparticles by Methanol Adsorption: A TPD and DRIFTS Study

The adsorption of methanol on pure ZnO and Au‐decorated ZnO nanoparticles and its thermal decomposition monitored by temperature‐programmed desorption (TPD) experiments and by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), both applied under continuous flow conditions in fixed bed reactors, is reported. Two distinguishable methoxy species are formed during methanol adsorption on ZnO differing in the C? O stretching bands. During the subsequent TPD experiments two different H₂ peaks are observed, indicating the conversion of methoxy into formate species. By applying different heating rates, activation energies of 109 kJ mol^?1 and 127 kJmol^?1 for the selective oxidation of the two methoxy species are derived. Correspondingly, the methoxy decomposition results in two distinguishable formate species, which are identified by the asymmetric and symmetric OCO stretching bands on pure ZnO and Au/ZnO. Based on the decreased intensities of the OH bands during methanol adsorption, which are specific for the various ZnO single crystal surfaces, on the different reactivities of these surfaces, and on the formate FTIR bands observed on ZnO single crystal surfaces, the two methoxy and the corresponding formate species are identified to be adsorbed on the exposed less reactive non‐polar ZnO(${10\bar 10}$ ) surface and on the highly reactive polar ZnO(${000\bar 1}$ ) surface. The simultaneous formation of H₂, CO, and CO₂ at about 550–600 K during the TPD experiments indicate the decomposition of adsorbed formate species. The CO/CO₂ ratio decreases with increasing Au loading, and a broad band due to electronic transitions from donor sites to the conduction band is observed in the DRIFT spectra for the Au‐decorated ZnO nanoparticles. Thus, the presence of the Au nanoparticles results in an enhanced reducibility of ZnO facilitating the generation of oxygen vacancies.     

Improvement of glass ionomer restoration by adding ZnO nanoparticles prepared by laser in (Vitro study)

The technique of pulsed laser ablation in liquid media was successfully used to prepare zinc oxide ZnO nanoparticles NPs to enhance glass ionomer GI restorative. The synthesized ZnO NPs were confirmed using UV–Visible spectroscopy, XRD, and TEM. The absorption spectra revealed that the absorbance intensity of the prepared ZnO NPs increased as the number of laser pulses increased, with an absorbance peak at 230 nm due to quantum confinement. The crystalline nature of NPs with hexagonal structure is revealed by XRD analysis. The TEM images demonstrated the nanorod shape with a length of about 3.33 nm and there were spherical nanoparticles ranging from 5 nm to 30 nm. ZnO NPs with and without GI were tested for antibacterial activity against Streptococcus mutans bacteria, which shows slight improvement after adding ZnO NPs to glass ionomer as a result of containing effective ingredients in its composition. The agar well diffusion method results revealed that ZnO with GI had a higher antibacterial activity compared with pure ZnO NPs. Finally, the compressive strength test illustrated significant enhancement of up to 50% associated with the ZnO NP's concentration increase.     

Recent Advances of Zinc-based Antimicrobial Materials

Zinc has been widely utilized as an antimicrobial material, often in the form of complexes or zinc oxide nanoparticles. The efficacy of zinc complexes are often due to the synergistic effect of both the zinc ions and the attached organic ligands. In contrast, the nanoparticle effect of ZnO, and the photocatalytic generation of reactive oxygen species (ROS) has been postulated to be the effective mechanism of ZnO as a biocide. Recently, new forms of zinc-based biocidal materials have been reported with distinct antimicrobial mechanisms. This minireview summarizes these recent advances, including zinc-based nano-arrays, MOF-based ROS release and zinc composites that can self-generate ROS.     

Preparation of styrene polymer/ZnO nanocomposite latex via miniemulsion polymerization and its antibacterial property

Styrene polymer/ZnO nanocomposite latex was fabricated using miniemulsion polymerization in the presence of coupling agent 3-aminopropyltriethoxysilane (APTES) and hexadecane as hydrophobe. The size distribution and morphology of the composite latex particles were characterized by dynamic light scattering and transmission electron micrograph. X-ray photoelectron spectroscopy and Fourier transform infrared spectrophotometer results demonstrate that ZnO nanoparticles were encapsulated into polymer phases. The coupling treatment of ZnO with APTES can improve the dynamic contact angles of ZnO nanoparticle with water to enhance its hydrophobicity. When 0.6% APTES to ZnO (wt/wt) is used to modify ZnO, the encapsulation efficiency of ZnO reaches to 95%. It shows that the high encapsulation efficiency improves dispersion of ZnO nanoparticles in polymer film by scanning electron microscope. The stable structural hybrid latex can adequately exert unique function of nanoparticles in coatings. It indicates that the coatings added the composite latex exhibits perfect antibacterial activity, which has a tremendous potentiality in the field of coating materials.     

Structure,surface analysis and bioactivity of Mn doped zinc oxide nanoparticles

Undoped zinc oxide nanoparticles and Mn (5 atomic % & 10 atomic %) doped zinc oxide nanoparticles were prepared by soft chemical method. Antibacterial, antioxidant and anticancer activities in breast cancer cell line MDAMB231 of prepared nanoparticles were investigated. The nanoparticles were characterized using XRD, SEM, EDAX, UV–Vis, FT-IR, and room temperature PL Analysis. Antimicrobial activity was tested against both gram positive and gram negative human pathogens. The antioxidant potential of prepared nanoparticles was estimated using Phosphomolybdate and DPPH assay. The MTT assay was used for cytotoxicity evaluation of prepared nanoparticles against breast cancer cell line MDAMB231. XRD patterns confirmed the nanoparticles were crystallized hexagonal wurtzite structure with an average size of 38.95 ?nm. The absorption wavelength was observed at 361 ?nm in UV–Vis spectrum of Mn (10 atomic %) doped ZnO nanoparticles. The Mn (5 atomic %) doped ZnO nanoparticles exhibited significant antibacterial activity against the gram negative bacteria Escherichia coli, Klebsiella pneumonia at all concentrations. Undoped zinc oxide nanoparticles and Mn doped zinc oxide nanoparticles were effective against the breast cancer cell line MDAMB231.     

Sustainable green synthesis of silver nanoparticles using Sambucus ebulus phenolic extract (AgNPs@SEE): Optimization and assessment of photocatalytic degradation of methyl orange and their in vitro antibacterial and anticancer activity

The biogenic approach in the synthesis of nanoparticles provides an efficient alternative to the chemical synthesis system. Furthermore, the ecofriendly synthesis of metallic nanoparticles is developing rapidly due to its wide applications in sciences. In this research, metallic silver nanoparticles (AgNPs) were biosynthesized using Sambucus ebulus (S. ebulus; AgNPs@SEE) extract for the evaluation of efficient antibacterial, anticancer, and photocatalyst activities. The reaction parameters including temperatures, contact time, and AgNO₃ concentration were discussed and optimized. The optimized nanoparticles (AgNPs@SEE) showed cubic structure, spherical morphology with the average size of 35–50 nm. The photocatalytic performance of AgNPs was assessed by degradation of methyl orange at different concentrations of AgNPs@SEE (10 and 15 µl) under sun-light irradiation. About 95.89% of the pollutant was degraded (after 11 min), when 10 μl of nanocatalyst used. Also, the degradation of contaminant increased (about 95.47% after 7 min) by increasing the nanoparticle concentration to 20 μl. All in all, the results showed that the percentage of pollutant degradation increased with increasing the concentration of nanocatalyst. Furthermore, anticancer activity of AgNPs@SEE on human cancer cell lines (AGS and MCF-7), and antibacterial activity on both Gram-positive and Gram-negative microorganisms were studied. The synthesized AgNPs@SEE exhibited superior performance on cancer cell lines and effective antibacterial properties against Gram-positive microorganisms (like MIC value of 1.5 µg/ml for S. aureus) than Gram-negative microorganisms. All these investigations revealed that silver nanoparticles synthesized by natural extract have the potential to use as low-cost and efficient nanoparticles for environmental and biomedical applications.     

高效广谱复合光催化抗菌剂Ag-AgVO3/BiVO4的设计合成及抗菌机制

合成了一种具有树叶状形貌的Ag-AgVO₃/BiVO₄复合光催化抗菌剂, 并对其晶体结构、 形貌、 组成及光学性质等进行了表征. 研究结果表明, 以3,3',5,5'-四甲基联苯胺(TMB)的氧化反应为模型, Ag-AgVO₃/BiVO₄表现出优异的光响应类氧化酶活性. 光催化抗菌实验结果表明, Ag-AgVO₃/BiVO₄对金黄色葡萄球菌和大肠杆菌均具有良好的抗菌效果, 4 min内的抗菌效率可以达到99%以上. 采用多种实验方法系统研究了其抗菌机制: 活性物种捕获剂实验和细胞内活性氧荧光标记实验表明, 在可见光照射下, Ag-AgVO₃/BiVO₄所产生的电子与O₂反应生成的·O₂^?起主要作用; Live/Dead细胞的荧光实验、 扫描电子显微镜形貌观察实验以及处理前后细胞内外核酸和蛋白质含量的测定实验结果均证实了·O₂^?可以破坏细胞膜的完整性, 导致细胞内容物的破坏和流出, 从而造成细菌死亡. 另外, Ag-AgVO₃/BiVO₄对包括革兰氏阳性菌、 革兰氏阴性菌和真菌在内的9种致病菌均具有良好的抗菌效果, 说明其具有广谱抗菌性能.     

Co-doped ZnO nanoparticles synthesized by an adapted sol–gel method: effects on the structural,optical, photocatalytic and antibacterial properties

Pure and Co-doped ZnO nanoparticles were synthesized with different cobalt levels (1–10 mol%) via adapted sol–gel method using water as solvent and characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy and photoacoustic absorption spectroscopy. The results showed that all the samples have hexagonal wurtzite structure, with no evidence of any secondary phases until 10 mol% of the dopant. The average crystallite size of the samples was in the range of 25–50 nm, do not showing significant differences with the increase of the dopant level. However, the band gap energy of the nanoparticles decreases from 2.98 eV (pure ZnO) to 1.95 eV (10 mol% of Co). The photocatalytic activity of the samples was evaluated on the removal of methylene blue under visible light irradiation, which revealed an efficiency reduction by Co-doping ZnO. The antibacterial property was carried out indicating activity of the prepared samples against gram-positive bacteria.