A Study of Zn-Ca Nanocomposites and Their Antibacterial Properties

This study aimed to develop Ca²⁺ doped ZnO nanoparticles (NPs) and investigate their antibacterial properties against microorganisms of dental interest. Zn-Ca NPs were synthesized by the sol-gel method with different concentrations of Ca²⁺ (1, 3, and 5 wt. %) and subsequently characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-vis spectroscopy and Fourier transform infrared spectroscopy (FT-IR). The Kirby–Bauer method was used to measure antibacterial effects. NPs showed the wurzite phase of ZnO and bandgap energies (Eg) from 2.99 to 3.04 eV. SEM analysis showed an average particle size of 80 to 160 nm. The treatments that presented the best antibacterial activity were Zn-Ca 3% and Zn-Ca 5%. ZnO NPs represent an alternative to generate and improve materials with antibacterial capacity for dental applications.     

Development of g-C3N4/ZnO nanocomposite as a novel,highly effective and durable photocatalytic antibacterial coating for cotton fabric

Photocatalytic antibacterial coats are considered among the best solutions to bacterial contamination of fabrics, with the drawback of reduced efficacy after continued use and washing. In the present study, the g-C₃N₄/ZnO (CNZ) nanocomposite has been introduced as a novel cotton fabric coating, with high durability, and CNZ nanopowders were synthesized using a two-step thermal synthesis process and directly coated onto cotton fabric using the sonication technique. The synthesized nanoparticles (NPs) were examined using X-ray diffraction (XRD), UV–visible spectroscopy, photoluminescence (PL), Brunauer-Emmett-Teller (BET), and Fourier transform infrared (FTIR) analyzes. Besides, the SEM analysis confirmed the successful deposition of NPs on cotton fabric. The photodegradation of methylene blue (MB) stain was assessed as a functional test for the photocatalytic effectiveness of the coated fabric, then its antibacterial properties were evaluated under visible light, by direct contact with bacterial suspensions and culturing. The results revealed that the CNZ-coated cotton fabric containing 30% ZnO (CNZ-30) has significant photocatalytic antibacterial activity against both Escherichia coli (gram-negative), and Staphylococcus aureus (gram-positive) bacteria. The bacterial reduction rate of CNZ-30 coated fabric for both E. coli and S. aureus was above 98%, even after 18 washing cycles. This excellent performance is attributed to the effective coupling of ZnO with g-C₃N₄, improved light absorption, and reduced e⁻/h⁺ pair recombination rates. This study novel coating method can offer an environmentally friendly, cost-effective, and simple process to manufacture hybrid CNZ antibacterial cotton in the textile industry.     

Sol–gel preparation and characterization of antibacterial and self-cleaning hybrid nanocomposite coatings

ZnO–TiO₂, SiO₂–TiO₂, and SiO₂–TiO₂–ZnO hybrid nanocomposite coatings were synthesized based on sol–gel precursors including tetramethoxysilane (TMOS), 3-glycidoxypropyl trimethoxysilane (GPTMS), tetra(n-butyl orthotitanate) (TBT), and zinc acetate dihydrate. The hybrid network was characterized by FTIR, FESEM, and EDAX techniques. Results indicated that inorganic particles’ size was of nanoorder (20–30 nm), with very uniform distribution and dispersion. Photocatalytic and self-cleaning activities of these coatings were further investigated by degradation of methylene blue in an aqueous solution (20 ppm) at visible light irradiation, indicating photocatalytic performance of the coatings containing ZnO and TiO₂ nanoparticles. The antibacterial effect of the coatings was investigated for inhibition and inactivation of cell growth, with the results showing the same antibacterial activity for ZnO–TiO₂ and SiO₂–TiO₂–ZnO coatings against Escherichia coli and Staphylococcus aureus; the activity was, however, higher than that of SiO₂–TiO₂ hybrid nanocomposite coatings.     

Antibacterial activity of silver nanoparticles prepared by a chemical reduction method

Silver nanoparticles were obtained by chemical reduction of silver nitrate in water with sodium borohydride (NaBH₄) in the presence of SDS (sodium dodecyl sulfate) as a stabilizer. The synthesized silver nanoparticles were characterized by UV-vis spectroscopy (UV-vis) and transmission electron microscopy (TEM). The formation of silver nanoparticles was confirmed from the appearance of surface plasmon absorption maxima at 400 nm by UV-vis. TEM showed the spherical nanoparticles with size in 10–20 nm. The antibacterial activity of silver nanoparticles was tested by using Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coil (E. coli). The silver nanoparticles, whose bacterial activity was dependent on the aggregation degree between particles, exhibited bacterial activity against S. aureus and E. coli.     

One Step Synthesis of NiO Nanoparticles via Solid-State Thermal Decomposition at Low-Temperature of Novel Aqua(2,9-dimethyl-1,10-phenanthroline)NiCl2 Complex

[NiCl₂(C₁₄H₁₂N₂)(H₂O)] complex has been synthesized from nickel chloride hexahydrate (NiCl₂·6H₂O) and 2,9-dimethyl-1,10-phenanthroline (dmphen) as N,N-bidentate ligand. The synthesized complex was characterized by elemental analysis, infrared (IR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy and differential thermal/thermogravimetric analysis (TG/DTA). The complex was further confirmed by single crystal X-ray diffraction (XRD) as triclinic with space group P-1. The desired complex, subjected to thermal decomposition at low temperature of 400 ºC in an open atmosphere, revealed a novel and facile synthesis of pure NiO nanoparticles with uniform spherical particle; the structure of the NiO nanoparticles product was elucidated on the basis of Fourier transform infrared (FT-IR), UV-vis spectroscopy, TG/DTA, XRD, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDXS) and transmission electron microscopy (TEM).     

Optical properties of ZnO/BaCO3 nanocomposites in UV and visible regions

Pure zinc oxide and zinc oxide/barium carbonate nanoparticles (ZnO-NPs and ZB-NPs) were synthesized by the sol–gel method. The prepared powders were characterized by X-ray diffraction (XRD), ultraviolet–visible (UV–Vis), Auger spectroscopy, and transmission electron microscopy (TEM). The XRD result showed that the ZnO and BaCO₃ nanocrystals grow independently. The Auger spectroscopy proved the existence of carbon in the composites besides the Zn, Ba, and O elements. The UV–Vis spectroscopy results showed that the absorption edge of ZnO nanoparticles is redshifted by adding barium carbonate. In addition, the optical parameters including the refractive index and permittivity of the prepared samples were calculated using the UV–Vis spectra.

PACS

81.05.Dz; 78.40.Tv; 42.70.-a.     

Experimental and theoretical study of visible light driven scandium (III) doped ZnO for antibacterial activity

ZnO was doped with Sc(III) ions to obtain a low-cost and environment-friendly antibacterial material with highly synergistic antimicrobial activity. The combination of experimental results and theoretical insights was used to describe the effect of Sc doping on the electronic and structural properties of ZnO. Sc(III)-doped ZnO materials with different Sc(III) contents were deposited on white carbon black (WCB) by a facile sol-gel method. The Sc(III) doped antibacterial materials were characterized by FESEM, EDX, HR-TEM, BET, XPS, XRD, ICP-OES, UV–visible spectroscopy, Fastsage and Materials Studio (MS). The antibacterial activities of Zn WCB and Zn–Sc WCB were determined by counting Escherichia coli (E. coli) and Staphylococcus aureus (S.aureus) colonies on bacterial culture plates. The results show that the specific surface area of Sc-doped Zn on WCB was increased by 31.9 m²/g compared to Zn WCB. The optimum doping ratio of Zn and Sc was determined in Zn_0.9574Sc_0.0426O cut from hexagonal wurtzite structure ZnO. Moreover, pure ZnO and Zn_0.9574Sc_0.0426O models were established by density functional theory (DFT). The experimental results and DFT calculations demonstrated that ZnO WCB possessed excellent antibacterial properties after doping with Sc. This improved antibacterial activity was due to the effects of Sc₂O₃ on the ZnO lattice, which resulted in the generation of excess reactive oxygen species (ROS).     

Sol-gel synthesis and antibacterial study on BC/ZnO/TiO2 nanocomposite treated by DC glow discharge plasma

Nanocomposite material of bamboo charcoal (BC), zinc oxide (ZnO), and titanium dioxide (TiO₂) has prepared via sol–gel method. The synthesized nanocomposite surface was modified by a DC glow discharge plasma treatment. Characterization methods such as BET, SEM, XRD, FTIR, UV, and EDAX are utilized to examine the presence of all the three materials and their combination structure. The combined and plasma-modified surface structure of the bamboo charcoal/zinc oxide/titanium dioxide (BC/ZnO/TiO₂) nanocomposite has shown by microscopic images in step by step. The phase structure of the prepared nanocomposite has been identified by X-ray diffraction and the crystalline size of the composite falls between 20 and 30 nm. The antibacterial behavior of the prepared nanocomposite was assessed through disk diffusion plate method and best antibacterial performance was observed. The metal oxides and plasma treatment increased the property of the synthesized nanocomposite and also the results gave extended results compared to BC/ZnO and BC/TiO₂ in all formats.     

In situ preparation of nano ZnO/hyperbranched polyimide hybrid film and their optical properties

Novel hybrid films of fluorinated hyperbranched polyimide (HBPI) and zinc oxide (ZnO) were prepared via the in situ sol-gel polymerization technique, in which mono-ethanolamine (MEA) was used as the coupling agent between the termini of HBPI and the precursor of ZnO. The hybrid films were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) absorption, ultraviolet-visible (UV-vis) absorption, and fluorescent excitation/emission spectroscopy. The films, which originated from the colourless fluorinated HBPI structure and homogeneously dispersed ZnO nanoparticles, exhibited good optical transparency. Furthermore, two kinds of model compounds with and without ZnO and a HBPI film blended with ZnO microparticles were prepared to clarify the fluorescence mechanism in the pristine HBPI and in situ hybrid films. Efficient energy transfer from the ZnO nanoparticles to the aromatic HBPI main chains was observed in the in situ hybrid films, whereas energy transfer occurred only from the locally excited (LE) states to the charge-transfer (CT) state in the HBPI film. These facts demonstrate that the peripheral termini of HBPI are covalently bonded to ZnO particles via the MEA function, which operates as an effective pathway for energy transfer to give intense fluorescent emission.     

Antibacterial efficiency of alkali-free bio-glasses incorporating ZnO and/or SrO as therapeutic agents

A series of seven alkali-free silica-based bioactive glasses (SBG) with ZnO and/or SrO additives (in concentrations of 0–12?mol%) were synthesized by melt-quenching, aiming to delineate a candidate formulation possessing (i) a coefficient of thermal expansion (CTE) similar to the one of titanium (Ti) and its medical grade super-alloys (crucial for the future development of mechanically adherent implant-type SBG coatings) and (ii) antibacterial efficiency, while (iii) conserving a good cytocompatibility. The SBGs powders were multi-parametrically evaluated by X-ray diffraction, Fourier transform infrared and micro-Raman spectroscopy, dilatometry, inductively coupled plasma mass spectrometry, antibacterial (against Staphylococcus aureus and Escherichia coli strains) suspension inhibition and agar diffusion tests, and human mesenchymal stem cells cytocompatibility assays. The results showed that the coupled incorporation of zinc and strontium ions into the parent glass composition has a combinatorial and additive benefit. In particular, the “Z6S4” formulation (mol%: SiO₂—38.49, CaO—32.07, P₂O₅—5.61, MgO—13.24, CaF₂—0.59, ZnO—6.0, SrO—4.0) conferred strong antimicrobial activity against both types of strains, minimal cytotoxicity combined with good stem cells viability and proliferation, and a CTE (~?8.7?×?10^?6 ×?°C^?1) matching well those of the Ti-based implant materials.     

Room temperature synthesis and optical properties of SrMoO4 crystallites by w/o microemulsion

SrMoO₄ crystallites with varying morphology have been prepared by the chemical reaction of strontium chloride and sodium molybdate in a reverse microemulsion system consisting of water, OP (p-octyl polyethylene glycol phenylether, non-ionic surfactant), 1-pentanol (co-surfactant) and cyclohexane (oil). The resultant powders were characterized in detail by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and photoluminescent spectra techniques (PL), respectively. It was found that SrMoO₄ crystallites with different morphologies could be synthesized by the microemulsion process with different aging times. PL spectra showed that the spindle-shape SrMoO₄ crystallites with a higher aspect ratio resulted in better photoluminescence property.     

Modification of mesoporous structure of silver-doped bioactive glass with antibacterial properties for bone tissue applications

Silver-containing mesoporous bioglasses powders with SiO₂–CaO–P₂O₅–Ag₂O composition have been successfully synthesized by sol-gel and evaporation-induced self-assembly (EISA) methods in presence of various amounts of surfactant (Pluronic-F127). The morphology and crystal structure of the powders were characterized by scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD). Also, the textural properties of samples have been evaluated by adsorption-desorption, Langmuir and BET methods. Accordingly, powders had a smooth surface morphology with cubic mesoporous structure and a desired surface area and pore volume. The in vitro bioactivity was assessed by SEM, XRD and Fourier transform infrared spectroscopy (FTIR) analyses. All samples enhance the formation of HA after soaking the material in simulated body fluid (SBF) solution. The antibacterial property of samples was evaluated to investigate the effect of silver content in chemical composition. The results showed an adequate antibacterial activity of the samples against Escherichia coli, Salmonella and Listeria monocytogenes.     

Preparation and characterization of a novel conducting nanocomposite blended with epoxy coating for antifouling and antibacterial applications

In this study, novel epoxy-based paint was synthesized to be applied on carbon steel. The composition of the paint mainly contains epoxy mixed with an electronically conductive polymer, polyaniline (PANI), alone and combined with its nanocomposite derivation containing ZnO nanorods as an additive. The antifouling properties of the paint applied on carbon steel were investigated. The conductive nanocomposite was synthesized by an in situ chemical oxidative method of aniline in the presence of ZnO nanorods and then well characterized. The antifouling behavior was evaluated for 9 months in the Caspian Sea and Persian Gulf. Results revealed that epoxy/PANI–ZnO nanocomposite coating can prevent accumulation of marine macroorganisms on the coated panel. In addition, the epoxy coating comprising PANI–ZnO nanocomposite as well as the epoxy/ZnO coating exhibit significant antibacterial characteristics against (E. coli and S. epi). We interpret the antifouling and antibacterial behavior of the paint with (i) the presence of emeraldine salt structure in PANI which develops a surface pH in a range of 4–5 preventing the adhesion of microorganisms on the surface and (ii) the antibacterial and antifouling properties of zinc oxide nanorods that occurred by the production of hydrogen peroxide on the surface of the coating.     

Cellulose Nanocrystals/ZnO as a Bifunctional Reinforcing Nanocomposite for Poly(vinyl alcohol)/Chitosan Blend Films: Fabrication,Characterization and Properties

In this study, cellulose nanocrystals/zinc oxide (CNCs/ZnO) nanocomposites were dispersed as bifunctional nano-sized fillers into poly(vinyl alcohol) (PVA) and chitosan (Cs) blend by a solvent casting method to prepare PVA/Cs/CNCs/ZnO bio-nanocomposites films. The morphology, thermal, mechanical and UV-vis absorption properties, as well antimicrobial effects of the bio-nanocomposite films were investigated. It demonstrated that CNCs/ZnO were compatible with PVA/Cs and dispersed homogeneously in the polymer blend matrix. CNCs/ZnO improved tensile strength and modulus of PVA/Cs significantly. Tensile strength and modulus of bio-nanocomposite films increased from 55.0 to 153.2 MPa and from 395 to 932 MPa, respectively with increasing nano-sized filler amount from 0 to 5.0 wt %. The thermal stability of PVA/Cs was also enhanced at 1.0 wt % CNCs/ZnO loading. UV light can be efficiently absorbed by incorporating ZnO nanoparticles into a PVA/Cs matrix, signifying that these bio-nanocomposite films show good UV-shielding effects. Moreover, the biocomposites films showed antibacterial activity toward the bacterial species Salmonella choleraesuis and Staphylococcus aureus. The improved physical properties obtained by incorporating CNCs/ZnO can be useful in variety uses.     

Construction of Er-doped ZnO/SiO2 composites with enhanced antimicrobial properties and analysis of antibacterial mechanism

Herein, silica carrier was used as underlying structure to prepare composite material loaded with rare earth element Er and Zn. Rare earth elements can improve antimicrobial effects of ZnO due to their specific electronic structure. Er–ZnO/SiO₂ hybrid antibacterial material was prepared through sol-gel method and its structure and morphology were characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, inductively coupled plasma emission spectroscopy and Brunauer-Emmett-Teller measurements. E. coli and S. aureus were selected as model bacteria to assess antibacterial activity of prepared hybrid material by plate coating method. Er–ZnO/SiO₂ exhibited good antibacterial activity towards E. coli and S. aureus. Increase in Er³⁺ concentration from 0.12% to 1.10% led to increase in antibacterial performance followed by subsequent decrease. Improving effect of Er relied on the molar ratio of Er doped in ZnO/SiO₂ hybrid material. The optimal sample was found to be 0.60%Er–ZnO/SiO₂, with antibacterial rates of 93.71% and 70.46% against E. coli and S. aureus, respectively. Antibacterial mechanism was assessed by fluorescence detection of reactive oxygen species. In addition, flame atomic absorption spectrometry was used to measure the amount of released Zn²⁺. Results also showed that 0.60%Er–ZnO/SiO₂ hybrid material generated more reactive oxygen species, released more Zn²⁺ ions, and had the largest surface area, which improved its antibacterial rate. Thus, Er enhanced antibacterial properties of ZnO/SiO₂, providing these composite materials with great potential as antibacterial products.     

Dual role of activated carbon as fuel and template for solution combustion synthesis of porous zinc oxide powders

In this work, nanosized zinc oxide (ZnO) powders were fabricated by urea–nitrate solution combustion synthesis using activated carbon as a structure-directing template and secondary fuel at different fuel–oxidant ratios. The as-synthesized powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N₂ adsorption–desorption measurements, UV–Vis diffuse reflectance spectroscopy, and photoluminescence. The effect of fuel amount on photocatalytic activity of ZnO powders was evaluated by the degradation of an azo dye Orange G. It was observed that combustion synthesis with activated carbon as a secondary fuel had a profound effect on reducing crystallite size and enhancement of specific surface area. The crystallite size of the as-synthesized powders varied from 46 to 26 nm. The ZnO powder prepared at a fuel–oxidant ratio of 1.8 possessed the small crystallite size and high specific surface area of 69 m²/g. It correspondingly resulted in the highest dye removal percentage of 99% with a rate constant of 0.027 min⁻¹. The improvement in dye degradation can be due to the synergistic interaction and interplay of enhanced surface area and catalytic ability of the photocatalyst. This study provides a simple single-step synthesis methodology to produce metal oxide nanopowders with tunable surface properties for high potential applications in catalysis, optoelectronics, and gas sensors.     

Controlled synthesis of (CuO-Cu2O)Cu/ZnO multi oxide nanocomposites by facile combustion route: A potential photocatalytic,antimicrobial and anticancer activity

Photocatalytic activity of (CuO-Cu₂O)Cu/ZnO hetero-junction nanocomposites along with their luminescent, biological applications in the progress of anticancer and antibacterial agents is investigated. The Cu and Zn bi-components modified (CuO-Cu₂O)Cu/ZnO nanocomposites were synthesized via facile combustion route in the presence of controlled fuel to oxidizer ratio and were characterized by X-Ray Diffraction (XRD) patterns, Transmission electron microscopy (TEM), High resolution Transmission electron microscopy (HRTEM), Scanning Electron Microscopy (SEM), X-ray photoelectron Spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL) and energy dispersive X-ray (EDX) analysis. The PL and UV–Visible diffused reflectance spectral (UV–Vis-DRS) techniques were used to measure the optical sensitivity and tuning of band gap in the samples. The excellent photocatalytic degradation of Methylene Blue and industrial waste water under Sunlight irradiation depends on the mass ratios of Cu/Zn. The findings show that the addition of a certain proportion of CuO, Cu₂O, ZnO, and Cu can promote efficiency in Sunlight harvesting and separation of charge carriers. Process parameters namely catalyst quantity, dye concentration and a proposal for the mechanism of degradation pathway, experiments for trapping and enhancer are investigated. The study of photoluminescence, CIE and CCT calculations suggests that the present nanocomposite may find applications as phosphor material in warm white LEDs. The second segment of this study deals with the investigation of antibacterial performance of composites upon Gram-negative and Gram-positive bacteria. The results indicate that nanocomposites can be used in antibacterial control systems and as an important growth inhibitor in various microorganisms. The cytotoxic effect of the (CuO-Cu₂O)Cu/ZnO (CCCZ11) nanocomposite was determined by colorimetric and flow cytometric cell cycle analysis. Our experimental results show that the nanocomposite can induce apoptosis and suppress the proliferation of HeLa cells. The applications of nanocomposites based on Cu, an abundant and inexpensive metal has created much interest in various multifunctional applications.     

Synthesis and Characterization of ZnO Nanorods and Nanodisks from Zinc Chloride Aqueous Solution

ZnO nanorods and nanodisks were synthesized by solution process using zinc chloride as starting material. The morphology of ZnO crystal changed greatly depending on the concentrations of Zn²⁺ ion and ethylene glycohol (EG) additive in the solution. The effect of thermal treatment on the morphology was investigated. Photocatalytic activities of plate-like Zn₅(OH)₈Cl₂ · H₂O and rod-like ZnO were characterized. About 18% of 1 ppm NO could be continuously removed by ZnO particles under UV light irradiation.     

Optical and electrical properties of p-type Ag-doped ZnO nanostructures

Zn_1−xAg_xO nanoparticles (NPs) (x=0, 0.02, 0.04, and 0.06) were synthesized by a sol–gel method. The synthesized undoped ZnO and Zn_1−xAg_xO-NPs were characterized by X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and UV–visible spectroscopy. The XRD patterns indicated that undoped and Ag-doped ZnO crystallize in a hexagonal wurtzite structure. The TEM images showed ZnO NPs with nearly spherical shapes, with particle size distributed over the nanometer range. Evidence of dopant incorporation is demonstrated in the XPS measurements of the Ag-doped ZnO NPs. The Raman measurements indicated that the undoped and Ag-doped ZnO-NPs had a high crystalline quality. From the result of UV–vis, the band-gap values of prepared undoped and Ag-doped ZnO were found to decrease with an increase in Ag concentration. The obtained undoped and Ag-doped ZnO nanoparticles were used as a source material to grow undoped and Ag-doped ZnO nanowires on n-type Si substrates, using a thermal evaporation set-up. Two probe method results indicated that the Ag-doped ZnO nanowires exhibit p-type properties.     

Antimicrobial properties of ZnO nanomaterials: A review

Waterborne diseases significantly affect the human health and are responsible for high mortality rates worldwide. Traditional methods of the treatment are now insignificant as maximum bacterial strains have developed multiple antibiotic resistance toward commonly used antibiotic drugs. Recently, ZnO nanostructures, due to their biocompatible nature, have attracted the attention of the scientific community to explore and to understand their cytotoxicity, interactions with biomolecules such as proteins, nucleic acids, fats, cell membranes, tissues, biological fluids, etc., and bio-safety for proper utilization in biomedical applications. Herein, we have reviewed the recent developments for the fabrication of ZnO nanomaterials with variable morphologies, factors influencing the growth, morphology and surface defects, and various laboratory methods to evaluate the antibacterial activities toward Gram-positive as well as Gram-negative bacterial strains. A comparative study is carried out to evaluate the mechanistic approach of ZnO nanomaterials toward Gram-positive as well as Gram-negative bacterial cells. ZnO nanomaterials can interact chemically as well as physically to exhibit antibacterial activities. Chemical interactions of the ZnO nanomaterials with bacterial cells lead to the photo-induced production of reactive oxygenated species (ROS), formation of H₂O₂, and release of Zn²⁺ ions. In contrast, the physical interaction can show biocidal effects through cell envelope rupturing, cellular internalization or mechanical damage. Finally, surface activation through amine functionalization of ZnO nanoparticles for better antibacterial effects and cytotoxicity of ZnO nanoparticles toward cancer cells is also reviewed.