Cytotoxicity of ZnO Nanoparticles Can Be Tailored by Modifying Their Surface Structure: A Green Chemistry Approach for Safer Nanomaterials

Directing mineralization of ZnO nanoparticles in cyanobacterial liquid crystalline polysaccharides for cancer therapies

Effective cancer therapy faces significant challenges, including non-selective toxicity, limited structural stability, inconsistent nanoparticle (NP) morphology, and instability under varying biological conditions. These issues hindering targeted delivery and therapeutic efficacy. Previous approaches using polysaccharide-based nanomaterials have shown promise; however, problems such as inconsistent NP sizes and shapes, poor mechanical stability, and limited pH resilience restrict their clinical potential. This study hypothesized that sacran, a cyanobacterial liquid crystalline (LC) polysaccharide, can stabilize ZnO NPs, allowing for controlled mineralization, enhanced stability, and selective cytotoxicity. We developed ZnO nanocomposite xerogels in an LC sacran matrix, yielding block-like ZnO NPs (25-70 nm) with high surface-area-to-volume ratios that improve cellular uptake in tumor environments. Incorporating these NPs into chemically crosslinked sacran matrices resulted in a 3-fold increase in mechanical strength and a 10-fold improvement in swelling capacity compared to physically crosslinked systems. Additionally, the sacran-ZnO nanocomposites demonstrated robust stability under various pH conditions, indicating their resilience in diverse biological environments. Cytotoxicity assays revealed that higher concentrations of ZnO NP selectively increased toxicity toward human lung cancer cells (A549), with less impact on human dermal fibroblasts (HDFa). Moreover, HDFa successfully attached to and proliferated on the smooth surfaces of the xerogels, emphasizing their compatibility with normal cells. This highlights the potential of sacran-ZnO nanocomposite xerogels as cancer-selective therapeutic materials, offering stability and effectiveness even under varying biological conditions, while addressing key challenges associated with earlier NP-based therapies.

ZnO Nanoparticle-Infused Vaterite Coatings: A Novel Approach for Antimicrobial Titanium Implant Surfaces

Loss of implant function is a common complication in orthopaedic and dental surgery. Among the primary causes of implant failure are peri-implant infections which often result in implant removal. This study demonstrates the development of a new antimicrobial titanium coating with ZnO nanoparticles of various sizes and morphologies immobilised in poly(allylamine hydrochloride) and alginate multilayers, combined with epitaxially grown vaterite crystals. The coated samples were characterised with various methods (FTIR, XRD, SEM) and surface properties were evaluated via water contact angle and surface charge measurements. Zinc ion release was quantified using ICP-MS. The antimicrobial efficacy of the coatings was tested against Staphylococcus aureus, Staphylococcus epidermidis, and Candida albicans while the biocompatibility was tested with preosteoblast cells (MC3T3-E1). Results demonstrated the successful preparation of a calcium carbonate/ZnO composite coating with epitaxially grown vaterite on titanium surfaces. The Zn ions released from ZnO nanoparticles dramatically influenced the morphology of vaterite where a new flower-like morphology was observed. The coated titanium surfaces exhibited robust antimicrobial activity, achieving over 90% microbial viability reduction for Staphylococcus aureus, Staphylococcus epidermidis, and Candida albicans. Importantly, the released Zn2+ concentrations remained below the cytotoxicity limit for MC3T3-E1 cells, showing potential for safe and effective implant applications.

Photocatalytic Degradation of Lincosamides in the Presence of Commercial Pigments: Kinetics, Intermediates, and Predicted Ecotoxicity

Lincomycin belongs to the antibiotics commonly used in veterinary medicine. Its residues are easily spread in the environment because of its physicochemical properties, including resistance to biodegradation and good solubility in water. One of the effective methods for the removal of lincomycin from wastewater is the photocatalytic process, but it is not widely used due to the price of photocatalysts. The aim of this work was to compare the photocatalytic efficiency and the mechanism of lincomycin degradation initiated by UVa radiation in the presence of TiO2-P25 and ZnO, as well as in the presence of industrial pigments commonly used in construction and containing TiO2. Lincomycin was found to undergo efficient photocatalytic degradation in the presence of a commercial TiO2-P25 photocatalyst, industrial pigments containing only anatase, and in the presence of ZnO. On the contrary, industrial pigments containing only rutile or a mixture of rutile and anatase practically did not show any photocatalytic activity. The composition of the solutions after the degradation of lincomycin in the presence of TiO2-P25 and ZnO differed significantly. Most of the identified organic degradation products contained conserved pharmacophores, and some of them could have been highly ecotoxic.

Revolutionizing healthcare: Harnessing nano biotechnology with zinc oxide nanoparticles to combat biofilm and bacterial infections-A short review

A crucial pathogenic mechanism in many bacterial diseases is the ability to create biofilms. Biofilms are suspected to play a role in over 80 % of microbial illnesses in humans. In light of the critical requirement for efficient management of bacterial infections, researchers have explored alternative techniques for treating bacterial disorders. One of the most promising ways to address this issue is through the development of long-lasting coatings with antibacterial properties. In recent years, antibacterial treatments based on metallic nanoparticles (NPs) have emerged as an effective strategy in the fight over bacterial drug resistance. Zinc oxide nanoparticles (ZnO-NPs) are the basis of a new composite coating material. This article begins with a brief overview of the mechanisms that underlie bacterial resistance to antimicrobial drugs. A detailed examination of the properties of metallic nanoparticles (NPs) and their potential use as antibacterial drugs for curing drug-sensitive and resistant bacteria follows. Furthermore, we assess metal nanoparticles (NPs) as powerful agents to fight against antibiotic-resistant bacteria and the growth of biofilm, and we look into their potential toxicological effects for the development of future medicines.

Uranium capture from aqueous solution using palm-waste based activated carbon: sorption kinetics and equilibrium

Carbonaceous materials produced from agricultural waste (palm kernel shell) by pyrolysis can be a proper type of low-cost adsorbent for wide uses in radioactive effluent treatment. In this context, the as-produced bio-char (labeled as PBC) and its sub-driven sulfuric acid and zinc oxide activated carbons (labeled as PBC-SA, and PBC-Zn respectively) were employed as adsorbents for uranium sorption from aqueous solution. Various analytical techniques, including SEM (Scanning Electron Microscopy), EXD (X-ray Diffraction), BET (Brunauer-Emmett-Teller), FTIR (Fourier Transform Infrared Spectroscopy), and Zeta potential, provide insights into the material characteristics. Kinetic and isotherm investigations illuminated that the sorption process using the three sorbents is nicely fitted with Pseudo-second-order-kinetic and Langmuir isotherm models. The picked data display that the equilibrium time was 60 min, and the maximum sorption capacity was 9.89, 16.8, and 21.9 mg/g for PBC, PBC-SA, and PBC-Zn respectively, which reflects the highest affinity for zinc oxide, activated bio-char, among the three adsorbents, for uranium taking out from radioactive wastewater. Sorption thermodynamics declare that the sorption of U(VI) is an exothermic, spontaneous, and feasible process. About 92% of the uranium-loaded PBC-Zn sorbent was eluted using 1.0 M CH3COONa sodium ethanoate solution, and the sorbent demonstrated proper stability for 5 consecutive sorption/desorption cycles.

Defect Engineering in Biomedical Sciences

With the promotion of nanochemistry research, large numbers of nanomaterials have been applied in vivo to produce desirable cytotoxic substances in response to endogenous or exogenous stimuli for achieving disease-specific therapy. However, the performance of nanomaterials is a critical issue that is difficult to improve and optimize under biological conditions. Defect-engineered nanoparticles have become the most researched hot materials in biomedical applications recently due to their excellent physicochemical properties, such as optical properties and redox reaction capabilities. Importantly, the properties of nanomaterials can be easily adjusted by regulating the type and concentration of defects in the nanoparticles without requiring other complex designs. Therefore, this tutorial review focuses on biomedical defect engineering and briefly discusses defect classification, introduction strategies, and characterization techniques. Several representative defective nanomaterials are especially discussed in order to reveal the relationship between defects and properties. A series of disease treatment strategies based on defective engineered nanomaterials are summarized. By summarizing the design and application of defective engineered nanomaterials, a simple but effective methodology is provided for researchers to design and improve the therapeutic effects of nanomaterial-based therapeutic platforms from a materials science perspective.

Phytofabrication and Characterisation of Zinc Oxide Nanoparticles Using Pure Curcumin

Zinc oxide and curcumin, on their own and in combination, have the potential as alternatives to conventional anticancer drugs. In this work, zinc oxide nanoparticles (ZnO NPs) were prepared by an eco-friendly method using pure curcumin, and their physicochemical properties were characterised. ATR-FTIR spectra confirmed the role of curcumin in synthesising zinc oxide curcumin nanoparticles (Green-ZnO-NPs). These nanoparticles exhibited a hexagonal wurtzite structure with a size and zeta potential of 27.61 ± 5.18 nm and -16.90 ± 0.26 mV, respectively. Green-ZnO-NPs showed good activity towards studied bacterial strains, including Escherichia coli, Staphylococcus aureus and methicillin-resistant Staphylococcus aureus. The minimum inhibitory concentration of Green-ZnO-NPs was consistently larger than that of chemically synthesised ZnO NPs (Std-ZnO-NPs) or mere curcumin, advocating an additive effect between the zinc oxide and curcumin. Green-ZnO-NPs demonstrated an efficient inhibitory effect towards MCF-7 cells with IC50 (20.53 ± 5.12 μg/mL) that was significantly lower compared to that of Std-ZnO-NPs (27.08 ± 0.91 μg/mL) after 48 h of treatment. When Green-ZnO-NPs were tested against Artemia larvae, a minimised cytotoxic effect was observed, with LC50 being almost three times lower compared to that of Std-ZnO-NPs (11.96 ± 1.89 μg/mL and 34.60 ± 9.45 μg/mL, respectively). This demonstrates that Green-ZnO-NPs can be a potent, additively enhanced combination delivery/therapeutic agent with the potential for anticancer therapy.

Comparative study on the effects of micro- and nano-sized zinc oxide supplementation on zinc-deficient mice

BACKGROUND

Zinc (Zn) is an essential cofactor for physiological homeostasis in the body. Zn oxide (ZnO), an inorganic compound that supplies Zn, exists in various sizes, and its bioavailability may vary depending on the size in vivo. However, comparative studies on the nutritional effects of micro-sized ZnO (M-ZnO) and nano-sized ZnO (N-ZnO) supplementation on Zn deficiency (ZnD) animal models have not been reported.

OBJECTIVES

This study investigated the nutritional bioavailability of N-ZnO and M-ZnO particles in dietary-induced ZnD mice.

METHODS

Animals were divided into six experimental groups: normal group, ZnD control group, and four ZnO treatment groups (Nano-Low, Nano-High, Micro-Low, and Micro-High). After ZnD induction, N-ZnO or M-ZnO was administered orally every day for 4 weeks.

RESULTS

ZnD-associated clinical signs almost disappeared 7 days after N-ZnO or M-ZnO administration. Serum Zn concentrations were higher in the Nano-High group than in the ZnD and M-ZnO groups on day 7 of ZnO treatment. In the liver and testis, Nano-Low and Nano-High groups showed significantly higher Zn concentrations than the other groups after 14-day treatment. ZnO supplementation increased Mt-1 mRNA expression in the liver and testis and Mt-2 mRNA expression in the liver. Based on hematoxylin-and-eosin staining results, N-ZnO supplementation alleviated histological damage induced by ZnD in the testis and liver.

CONCLUSIONS

This study suggested that N-ZnO can be utilized faster than M-ZnO for nutritional restoration at the early stage of ZnD condition and presented Mt-1 as an indicator of Zn status in the serum, liver, and testis.

Bryophyllum pinnatum leaf extract mediated ZnO nanoparticles with prodigious potential for solar driven photocatalytic degradation of industrial contaminants

In an era of environment-friendly development plant extract-based biological techniques for synthesizing nanoparticles have gained a lot of attention over traditionally famous chemical and physical synthesis techniques. In the present study we have synthesized biogenic zinc oxide nanoparticles (BPLE-ZnO NPs) using Bryophyllum pinnatum leaf extract, compared its native properties and solar-driven photocatalytic activity with chemically prepared ZnO nanoparticles (Chem-ZnO NPs). In order to characterize and compare the Chem-ZnO and BPLE-ZnO, various techniques were used, including UV-visible spectroscopy, x-ray diffractrometry, photoluminescence spectroscopy, field emission scanning electron microscopy, electron dispersive x-ray spectroscopy, fourier transform infrared spectroscopy, and zeta potential analyzer. The results revealed the formation of hexagonal wurtzite ZnO, with no significant difference between the two methods; however, the use of Bryophyllum pinnatum leaf extract in ZnO NPs synthesis resulted in reduced size, presence of biomolecules on its surface and better monodispersity than purely chemical synthesis. Further, the BPLE-ZnO NPs showed better efficiency in the solar-driven photocatalytic degradation of methylene blue (MB) dye compared to Chem-ZnO NPs. Under solar exposure at a dose of 0.50 mg/mL BPLE-ZnO, resulted in 97.31% photodegradation with a rate constant of 0.06 min-1 of 20 mg/L MB solution within just 60 min which was 9.51% higher compared to the Chem-ZnO NPs. The BPLE-ZnO NPs were also employed to investigate their solar-driven photocatalytic performance for degrading the pharmaceutical (Metronidazole and Amoxycillin) and textile pollutants (Methyl orange dye) under sunlight. The results show that Bryophyllum pinnatum leaf extract-mediated ZnO NPs have an excellent potential in solar-based photocatalytic applications.

Composite Coating for the Food Industry Based on Fluoroplast and ZnO-NPs: Physical and Chemical Properties, Antibacterial and Antibiofilm Activity, Cytotoxicity

Bacterial contamination of meat products during its preparation at the enterprise is an important problem for the global food industry. Cutting boards are one of the main sources of infection. In order to solve this problem, the creation of mechanically stable coatings with antibacterial activity is one of the most promising strategies. For such a coating, we developed a composite material based on "liquid" Teflon and zinc oxide nanoparticles (ZnO-NPs). The nanoparticles obtained with laser ablation had a rod-like morphology, an average size of ~60 nm, and a ζ-potential of +30 mV. The polymer composite material was obtained by adding the ZnO-NPs to the polymer matrix at a concentration of 0.001-0.1% using the low-temperature technology developed by the research team. When applying a composite material to a surface with damage, the elimination of defects on a micrometer scale was observed. The effect of the composite material on the generation of reactive oxygen species (H₂O₂, •OH), 8-oxoguanine in DNA in vitro, and long-lived reactive protein species (LRPS) was evaluated. The composite coating increased the generation of all of the studied compounds by 50-200%. The effect depended on the concentration of added ZnO-NPs. The antibacterial and antibiofilm effects of the Teflon/ZnO NP coating against L. monocytogenes, S. aureus, P. aeruginosa, and S. typhimurium, as well as cytotoxicity against the primary culture of mouse fibroblasts, were studied. The conducted microbiological study showed that the fluoroplast/ZnO-NPs coating has a strong bacteriostatic effect against both Gram-positive and Gram-negative bacteria. In addition, the fluoroplast/ZnO-NPs composite material only showed potential cytotoxicity against primary mammalian cell culture at a concentration of 0.1%. Thus, a composite material has been obtained, the use of which may be promising for the creation of antibacterial coatings in the meat processing industry.

Accelerative effect of nanohydrogels based on chitosan/ZnO incorporated with citral to heal the infected full-thickness wounds; an experimental study

Antimicrobial-resistant is a major challenge in to treat infected wounds, and new formulations should be produced. Citral (Citl), chitosan (Chsn), and zinc oxide (ZnO) nanoparticles may accelerate the wound healing process in terms of their antibacterial properties. This new study aimed to investigate the effects of ointments produced from ZnO/Chsn/Citl nanoparticles (NPs) to treat the infected wounds. Following the preparation of ZnO/Chsn/Citl-NPs, swelling behavior, the release of citral, toxicity, and antibacterial properties were evaluated. Base ointment, mupirocin, and ointments made from Chsn-NPs, Chsn/Citl-NPs, and ZnO/Chsn/Citl-NPs were used to treat the mice. The ointments' effects on wound contraction, total bacterial count, and immunofluorescence staining for TNF-α, TGF-β, and bFGF were tested. The synthesis of ZnO/Chsn/Citl-NPs was validated by XRD, FT-IR, DLS, and TEM findings. In higher dilutions, chitosan/citral and ZnO/Chsn/Citl-NPs indicated better antibacterial activity. Nanoparticles were safe up to concentration of the 0.5 mg/mL. The mice in Chsn/Citl and ZnO/Chsn/Citl-NPs treated groups showed higher (P < 0.05) wound contraction ratio and expressions for bFGF, and lower total bacterial count and expressions for TGF-β and TNF-α compared to control mice. Ointments prepared from ZnO/Chsn/Citl-NPs could compete with the commercial ointment of mupirocin and can be used to treat infected wounds after clinical studies.

Synthesis of Zinc Oxide Nanoparticles with Bioflavonoid Rutin: Characterisation, Antioxidant and Antimicrobial Activities and In Vivo Cytotoxic Effects on Artemia Nauplii

This study aims to synthesise zinc oxide nanoparticles with rutin (ZnO-R NPs) using a green synthesis approach and characterise the nanostructures for diverse biomedical applications. In this study, the optical and chemical properties of synthesised ZnO-R NPs were verified through Fourier transform infrared (FTIR) spectroscopy and ultraviolet-visible (UV-Vis) spectroscopy. The FTIR spectroscopy revealed a symmetric bending vibration peak of 460 cm⁻¹ for ZnO-R NPs, whereas UV-Vis spectroscopy showed a distinct absorption band at 395 nm. Moreover, the oval-shaped morphology of ZnO-R NPs was verified through scanning electron microscopy and transmission electron microscopy. The synthesised nanoformulation revealed a wurtzite structure with a crystallite size of 13.22 nm; however, the zeta potential value was recorded as −8.50 ± 0.46 mV for ZnO-R NPs. According to an antioxidant study, ZnO-R NPs demonstrated lower free-radical scavenging activity than pure rutin. The cytotoxicity study was conducted using a human breast cancer cell line (MCF-7). In vitro analysis verified that ZnO-R NPs exhibited significantly higher anticancer and microbial growth inhibition activities than standard ZnO NPs (ZnO Std NPs) and pure rutin. In addition, ZnO-R NPs revealed a significantly lower IC₅₀ value than the commercial ZnO Std NPs and pure rutin in MCF-7 cells (16.39 ± 6.03 μg/mL, 27 ± 0.91 μg/mL and 350 ± 30.1 μg/mL, respectively) after 48 h. However, synthesised ZnO-R NPs demonstrated no significant toxicity towards Artemia nauplii. These results highlight the synthesis of rutin-mediated ZnO NPs and their possible chemotherapeutic potential.

Construction of a 3D Metal-Organic Framework and Its Composite for Water Remediation via Selective Adsorption and Photocatalytic Degradation of Hazardous Dye

In this work, a new bimetallic Na(I)-Zn(II) metal-organic framework (MOF), formulated as [Na₂Zn₃(btc)₂(μ-HCOO)₂(μ-H₂O)₈] _n (1) (H₃btc = benzene tricarboxylic acid), and its composite (ZnO@1) have been successfully synthesized using solvothermal and mechanochemical solid grinding methods. 1 and ZnO@1 were characterized by diffraction [single-crystal X-ray diffraction (XRD) and powder XRD], spectroscopic (ultraviolet-visible diffuse reflectance spectroscopy and Fourier transform infrared spectroscopy), microscopic (transmission electron microscopy), and thermal (thermogravimetric analysis) methods. The surface area and porosity of 1 were determined using a Brunauer-Emmett-Teller analyzer. Single-crystal diffraction of 1 confirms that Na1 and Zn2 have octahedral coordination environments, whereas Zn1 has a tetrahedral coordination geometry. Topological simplification of 1 shows a 3,6-connected kgd net. Na(I)-Zn(II) MOF (1) is crystallized with slight porosity and exhibits good tendency toward the encapsulation of zinc oxide nanoparticles (ZnO NPs). The photocatalytic behaviors of 1 and its composite (ZnO@1) were investigated over MB dye under sunlight illumination with promising degradation efficiencies of 93.69% for 1 and 97.53% for ZnO@1 in 80 min.

Green route synthesis of ZnO nanoparticles using Senna auriculata aqueous flower extract as reducing agent and evaluation of its antimicrobial, antidiabetic and cytotoxic activity

The nanoparticles have unique and superior properties which make them applicable in almost every field of human life. Among the various methods that exist for the synthesis of nanoparticles, green synthesis is one of the best economic and eco-friendly methods compared with other conventional chemical methods. The nanoparticles synthesized by this method are also free from toxicity properties. This paper describes one such green synthesis method for zinc oxide nanoparticles (ZnO NPs) using the aqueous flower extract of Senna auriculata. The synthesized nanoparticles (SA-ZnO NPs) have been examined using UV-Vis spectrophotometer, photoluminescence spectroscopy, Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. The antibacterial and antifungal activities of the synthesized NPs were evaluated against gram-positive bacteria (S. aureus, B. subtilis), gram-negative bacteria (E. coli, S. typhi) and fungal organisms (C. albicans, A. nigar) using disc diffusion method. Furthermore, the antidiabetic and anticancer activities of the NPs were also been examined by α-amylase inhibition assay and MTT assay, respectively. These studies ensured that the SA-ZnO NPs have significant antimicrobial, antidiabetic and anticancer activities.

Effects of Metal Nanoparticles and Other Preparative Materials in the Environment on Plants: From the Perspective of Improving Secondary Metabolites

The influence of preparation material residues in wastewater and soil on plants has been paid more and more attention by researchers. Secondary metabolites play an important role in the application of plants. It was found that nanomaterials can increase the content of plant secondary metabolites in addition to their role in pharmaceutical preparations. For example, 800 mg/kg copper oxide nanoparticles (NPs) increased the content of p-coumaric acid in cucumber by 225 times. Nanoparticles can cause oxidative stress in plants, increase signal molecule, and upregulate the synthase gene expression, increasing the content of secondary metabolites. The increase of components such as polyphenols and total flavonoids may be related to oxidative stress. This paper reviews the application and mechanism of metal nanomaterials (Ag-NP, ZnO-NP, CeO₂-NP, Cds-NP, Mn-NP, CuO-NP) in promoting the synthesis of secondary metabolites from plants. In addition, the effects of some other preparative materials (cyclodextrins and immobilized molds) on plant secondary metabolites are also involved. Finally, possible future research is discussed.

Physicomechanical and Antimicrobial Characteristics of Cement Composites with Selected Nano-Sized Oxides and Binary Oxide Systems

In recent years, increasing attention has been paid to the durability of building materials, including those based on cementitious binders. Important aspects of durability include the increase of the strength of the cement matrix and enhancement of material resistance to external factors. The use of nanoadditives may be a way to meet these expectations. In the present study, zinc, titanium and copper oxides, used in single and binary systems (to better the effect of their performance), were applied as additives in cement mortars. In the first part of this work, an extensive physicochemical analysis of oxides was carried out, and in the second, their application ranges in cement mortars were determined. The subsequent analyses were employed in determining the physicochemical properties of pristine oxides: Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray fluorescence (EDXRF), scanning electron microscopy (SEM), measurement of the particle size distribution, as well as zeta potential measurement depending on the pH values. Influence on selected physicomechanical parameters of the cement matrix and resistance to the action of selected Gram-positive and Gram-negative bacteria and fungi were also examined. Our work indicated that all nanoadditives worsened the mechanical parameters of mortars during the first 3 days of hardening, while after 28 days, an improvement was achieved for zinc and titanium(IV) oxides. Binary systems and copper(II) oxide deteriorated in strength parameters throughout the test period. In contrast, copper(II) oxide showed the best antibacterial activity among all the tested oxide systems. Based on the inhibitory effect of the studied compounds, the following order of microbial susceptibility to inhibition of growth on cement mortars was established (from the most susceptible, to the most resistant): E. coli < S. aureus < C. albicans < B. cereus = P. aeruginosa < P. putida.

The Effect of Zn-Substitution on the Morphological, Magnetic, Cytotoxic, and In Vitro Hyperthermia Properties of Polyhedral Ferrite Magnetic Nanoparticles

The clinical translation of magnetic hyperthermia (MH) needs magnetic nanoparticles (MNPs) with enhanced heating properties and good biocompatibility. Many studies were devoted lately to the increase in the heating power of iron oxide MNPs by doping the magnetite structure with divalent cations. A series of MNPs with variable Zn/Fe molar ratios (between 1/10 and 1/1) were synthesized by using a high-temperature polyol method, and their physical properties were studied with different techniques (Transmission Electron Microscopy, X-ray diffraction, Fourier Transform Infrared Spectroscopy). At low Zn doping (Zn/Fe ratio 1/10), a significant increase in the saturation magnetization (90 e.m.u./g as compared to 83 e.m.u./g for their undoped counterparts) was obtained. The MNPs' hyperthermia properties were assessed in alternating magnetic fields up to 65 kA/m at a frequency of 355 kHz, revealing specific absorption rates of up to 820 W/g. The Zn ferrite MNPs showed good biocompatibility against two cell lines (A549 cancer cell line and BJ normal cell line) with a drop of only 40% in the viability at the highest dose used (500 μg/cm2). Cellular uptake experiments revealed that the MNPs enter the cells in a dose-dependent manner with an almost 50% higher capacity of cancer cells to accommodate the MNPs. In vitro hyperthermia data performed on both cell lines indicate that the cancer cells are more sensitive to MH treatment with a 90% drop in viability after 30 min of MH treatment at 30 kA/m for a dose of 250 μg/cm2. Overall, our data indicate that Zn doping of iron oxide MNPs could be a reliable method to increase their hyperthermia efficiency in cancer cells.

Synthesis and Characterization of Antibacterial Carbopol/ZnO Hybrid Nanoparticles Gel

This study recommends Carbopol/zinc oxide (ZnO) hybrid nanoparticles gel as an efficient antibacterial agent against different bacterial species. To this end, ZnO nanoparticles were synthesized using chemical precipitation derived from a zinc acetate solution with ammonium hydroxide as its precipitating agent under the effect of ultrasonic radiation. The synthesized ZnO nanoparticles were stabilized simultaneously in a freshly prepared Carbopol gel at a pH of 7. The chemical composition, phase identification, particle size and shape, surface charge, pore size distribution, and the BET surface area of the ZnO nanoparticles, as well as the Carbopol/ZnO hybrid Nanoparticles gel, were by XRD, SEM, TEM, AFM, DLS, Zeta potential and BET instruments. The results revealed that the synthesized ZnO nanoparticles were well-dispersed in the Carbopol gel network, and have a wurtzite-crystalline phase of spherical shape. Moreover, the Carbopol/ZnO hybrid nanoparticles gel exhibited a particle size distribution between ~9 and ~93 nm, and a surface area of 54.26 m2/g. The synthesized Carbopol/ZnO hybrid nanoparticles gel underwent an antibacterial sensitivity test against gram-negative K. pneumonia (ATCC 13883), Bacillus subtilis (ATCC 6633), and gram-positive Staphylococcus aureus (ATCC 6538) bacterial strains, and were compared with ampicillin as a reference antibiotic agent. The obtained results demonstrated that the synthesized Carbopol/ZnO hybrid nanoparticles gel exhibited a compatible bioactivity against the different strains of bacteria.

Comparison Study of Cytotoxicity of Bare and Functionalized Zinc Oxide Nanoparticles

In this paper, a study of the cytotoxicity of bare and functionalized zinc oxide nanoparticles (ZnO NPs) is presented. The functionalized ZnO NPs were obtained by various types of biological methods including microbiological (intra- and extracellular with Lactobacillus paracasei strain), phytochemical (Medicago sativa plant extract) and biochemical (ovalbumin from egg white protein) synthesis. As a control, the bare ZnO NPs gained by chemical synthesis (commercially available) were tested. The cytotoxicity was measured through the use of (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) dye as well as lactate dehydrogenase (LDH) assays against murine fibroblast L929 and Caco-2 cell lines. As a complementary method, scanning electron microscopy (SEM) was performed to assess the morphology of the tested cells after treatment with ZnO NPs. The microscopic data confirmed the occurrence of apoptotic blebbing and loss of membrane permeability after the administration of all ZnO NPs. The reactive oxygen species (ROS) concentration during the cell lines’ exposure to ZnO NPs was measured fluorometrically. Additionally, the photocatalytic degradation of methylene blue (MB) dye in the different light conditions, as well as the antioxidant activity of bare and functionalized ZnO NPs, is also reported. The addition of all types of tested ZnO NPs to methylene blue resulted in enhanced rates of photo-degradation in the presence of both types of irradiation, but the application of UV light resulted in higher photocatalytic activity of ZnO NPs. Furthermore, bare (chemically synthetized) NPs have been recognized as the strongest photocatalysts. In the context of the obtained results, a mechanism underlying the toxicity of bio-ZnO NPs, including (a) the generation of reactive oxygen species and (b) the induction of apoptosis, is proposed.

Saussurea lappa plant rhizome extract-based zinc oxide nanoparticles: synthesis, characterization and its antibacterial, antifungal activities and cytotoxic studies against Chinese Hamster Ovary (CHO) cell lines

The plant extracts are known for their anti-inflammatory, antifungal, antiviral and antibacterial properties. The use of plant extracts in the preparation of bio-materials increases their biological application. In this concern, herein reporting an eco-friendly procedure which is also a simple and cost effective, for the synthesis of Zinc Oxide nanoparticles (ZnONPs) using Saussurea lappa plant root (rhizome) extract as a fuel. The prepared nanoparticles were confirmed using various characterization techniques. The Dynamic light scattering data showed 123.5 nm particle size with -99.9 mv zeta potential which indicates excellent stability of the particles. The peak at 541 cm-1 in the IR spectrum is assigned to the stretching frequency of the zinc-binding to oxygen. The X-ray diffraction peaks confirm the close association with JCPDS Data Card No: 36-1451. The FESEM data revealed a hexagonal wurtzite structure with a hexagonal shape of synthesized ZnO nanoparticles. The antibacterial studies indicate the gram-negative strains showed better inhibition activity than gram-positive strains. Among Fungal strains, Aspergillus niger and flavus, Fusarium oxysporum, and Rhizopus oryzae showed good inhibition activity at higher concentrations. The cytotoxic data indicates the 5 μg/mL of the ZnO particles showed cytotoxicity on the CHO cell line and with IC50 value 3.164 ± 0.8956 μg/mL.

Green Synthesis and Biomedical Applications of ZnO Nanoparticles: Role of PEGylated-ZnO Nanoparticles as Doxorubicin Drug Carrier against MDA-MB-231(TNBC) Cells Line

The present study aimed to develop the synthesis of zinc oxide nanoparticles (ZnO-NPs) using the green method, with Aloe barbadensis leaf extract as a stabilizing and capping agent. In vitro antitumor cytotoxic activity, as well as the surface-functionalization of ZnO-NPs and their drug loading capacity against doxorubicin (DOX) and gemcitabine (GEM) drugs, were also studied. Morphological and structural properties of the produced ZnO-NPs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersion X-ray diffraction (EDX), UV-Vis spectrophotometry, Fourier-transform infrared analysis (FTIR), and X-ray diffraction (XRD). The prepared ZnO-NPs had a hexagonal shape and average particle size of 20–40 nm, with an absorption peak at 325 nm. The weight and atomic percentages of zinc (50.58% and 28.13%) and oxygen (26.71% and 60.71%) were also determined by EDAX (energy dispersive x-ray analysis) compositional analysis. The appearance of the FTIR peak at 3420 m–1 confirmed the synthesis of ZnO-NPs. The drug loading efficiency (LE) and loading capacity (LC) of unstabilized and PEGylated ZnO-NPs were determined by doxorubicin (DOX) and gemcitabine (GEM) drugs. DOX had superior LE 65% (650 mg/g) and higher LC 32% (320 mg/g) than GEM LE 30.5% (30 mg/g) and LC 16.25% (162 mg/g) on ZnO-NPs. Similar observation was observed in the case of PEG-ZnO-NPs, where DOX had enhanced LE 68% (680 mg/g) and LC 35% (350) mg/g in contrast to GEM, which had LE and LC values of 35% (350 mg/g) and 19% (190 mg/g), respectively. Therefore, DOX was chosen to encapsulate nanoparticles, along with the untreated nanoparticles, to check their in vitro antiproliferative potential against the triple-negative breast cancer (TNBC) cell line (MDA-MB-231) through the MTT (3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide) assay. This drug delivery strategy implies that the PEGylated biogenically synthesized ZnO-NPs occupy an important position in chemotherapeutic drug loading efficiency and can improve the therapeutic techniques of triple breast cancer.

Sono-synthesis approach improves anticancer activity of ZnO nanoparticles: reactive oxygen species depletion for killing human osteosarcoma cells

Aim: To investigate the effect of ultrasound during the synthesis of ZnO nanoparticles (NPs) on their anticancer activity. Materials & methods: ZnO NPs were synthesized in the presence and absence of ultrasonic irradiation. Biological tests were performed on human osteosarcoma cancer cells (Saos-2). Results: The sono-synthesized sample indicated higher cytotoxicity than the conventional one. (IC₅₀ = 16.48 ± 0.41 μg/ml for sonochemical ZnO; 26.96 ± 0.33 μg/ml for conventional ZnO). Both sonochemical and conventional samples acted like antioxidants and reduced intracellular reactive oxygen species level. This reduction was more significant in cells treated with the sono-synthesized sample. The sono-synthesized ZnO NPs showed more tumor selectivity than the conventional sample. Conclusion: Sono-synthesis of ZnO NPs by a bath sonicator could improve their anticancer activity.

Journey of ZnO quantum dots from undoped to rare-earth and transition metal-doped and their applications

Currently, developments in the field of quantum dots (QDs) have attracted researchers worldwide. A large variety of QDs have been discovered in the few years, which have excellent optoelectronic, antibacterial, magnetic, and other properties. However, ZnO is the single known material that can exist in the quantum state and can hold all the above properties. There is a lot of work going on in this field and we will be shorthanded if we do not accommodate this treasure at one place. This manuscript will prove to be a milestone in this noble cause. Having a tremendous potential, there is a developing enthusiasm toward the application of ZnO QDs in diverse areas. Sol-gel method being the simplest is the widely-favored synthetic method. Synthesis via this method is largely affected by a number of factors such as the reaction temperature, duration of the reaction, type of solvent, pH of the solution, and the precipitating agent. Doping enhances the optical, magnetic, anti-bacterial, anti-microbial, and other properties of ZnO QDs. However, doping elements reside mostly on the surface of the QDs. The presence of doping elements inside the core is still a major challenge for doping techniques. In this review article, we have focused on pure, rare-earth, and transition metal-doped ZnO QD properties, and the various synthetic processes and applications. Quantum confinement effect is present in nearly every aspect of the QDs. The effect of quantum confinement has also been summarized in this manuscript. Furthermore, the doping of rare earth elements and transition metal, synthetic methods for different organic molecule-capped ZnO QDs, mechanisms for reactive oxygen species (ROS) generation, drug delivery system for cancer treatment, and many more application are discussed in this paper.

Electrospinning nanofibrous graft preparation and wound healing studies using ZnO nanoparticles and glucosamine loaded with poly(methyl methacrylate)/polyethylene glycol

As wound dressing materials, electrospun nanofibrous scaffolds have a lot of promise. Electrospun nanofibrous scaffolds in combination with ZnO nanoparticles have antimicrobial and antioxidant properties, making electrospinning a successful technique for wound dressings.

Cytotoxicity of zinc oxide nanoparticles to innate and adaptive human immune cells

Zinc oxide nanoparticles (ZnO-NPs) are widely used in almost every area of life. Therefore, exposure to them is unavoidable, which makes it necessary to assess their safety for humans. This paper aims to determine toxicity of ZnO-NPs of two diameters toward human immune cells responsible for: innate response (U-937 and HL-60) and acquired response (COLO-720L and HUT-78). Mitochondrial activity, membrane integrity, degree of cellular lipid oxidation, induction of inflammation, and activation of the apoptosis pathway were evaluated to determine differences in cellular response to the tested nanoparticles. ZnO-NPs with a diameter of 100 and 130 nm cause significant cell mortality at 25 and 12 mg/L, respectively. Mitochondrial damage leads to the activation of the caspase cascade and, consequently, to cell apoptosis. ZnO-NPs also cause peroxidation of membrane lipids. Due to the photocatalytic properties of ZnO-NPs, the effect of ultraviolet (UV) irradiation on the degree of their toxicity was also investigated. However, UV irradiation enhances the toxic effect of nanoparticles mainly by weakening the cell's defense capabilities. ZnO-NPs are cytotoxic to human immune system, and they may cause both long-term and short-term negative effects.

Micro-Plasma Assisted Synthesis of ZnO Nanosheets for the Efficient Removal of Cr6+ from the Aqueous Solution

Herein, we report a micro-plasma assisted solvothermal synthesis and characterization of zinc oxide nanosheets (ZnO-NSs) and their application for the removal of Cr6+ ion from aqueous solution. The morphological investigations by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed the high-density growth of nanosheets with the typical sizes in the range of 145.8–320.25 nm. The typical surface area of the synthesized ZnO-NSs, observed by Brunauer-Emmett-Teller (BET), was found to be 948 m2/g. The synthesized ZnO-NSs were used as efficient absorbent for the removal of Cr6+ ion from aqueous solution. Various parameters such as pH, contact time, amount of adsorbate and adsorbent on the removal efficiency of Cr6+ ion was optimized and presented in this paper. At optimized conditions, the highest value for removal was 87.1% at pH = 2 while the calculated maximum adsorption capacity was ~87.37 mg/g. The adsorption isotherm data were found to be best fitted to Temkin adsorption isotherm and the adsorption process followed the pseudo-first-order kinetics. Furthermore, the toxicity of ZnO-NSs were also examined against fibroblast cells, which show favorable results and proved that it can be used for wastewater treatment.

The investigation of the parameters affecting the ZnO nanoparticle cytotoxicity behaviour: a tutorial review

In the last 30 years the research about zinc oxide nanoparticles (ZnO NPs) and their related toxicity has shown a boom. ZnO NPs show cytotoxicity for both prokaryotic and eukaryotic cells and many studies demonstrated their selective toxicity towards cancer cells. However, with the increasing number of publications, it is observed an increase in the discrepancies obtained between the various results. Soon the scientific community understood that the ZnO NC toxicity behaviour is affected by many factors, related not only to the ZnO NPs themselves, but also to the experimental conditions used. Many recent reviews discussed these parameters by reporting experimental evidence and tried to assess the general statements about the ZnO NP cytotoxicity. This information is extremely useful for the evaluation of which type of ZnO NPs is more or less suitable for a specific study or application. However, despite that, a deep comprehension of the ZnO NP behaviour in relation to the different experimental conditions is still lacking. Actually, a full understanding of the reasons behind the NP behaviour is essential to better assess their biological activity and in particular their therapeutic application, avoiding undesired effects both in the experimental and clinical contexts. This tutorial review aims to be an experimental and practical guide for scientists that faced with the use of ZnO NPs for biomedical applications and, in particular, for their therapeutic purposes. The driving idea is to not simply summarize the results reported in the literature, but to provide instruments for a deep comprehension of the mechanisms affecting the ZnO NP cytotoxicity and behavior. This review also aims to point out the critical experimental parameters to be considered when working with these NPs, as well as the main related risks and limitations that scientists have to face.

An Aqueous Facile Synthesis of 2,3-Dihydroquinazolin-4(1H)-One Derivatives by Reverse Zinc Oxide Micelles as Nanoreactor

A green synthetic protocol has been developed for the efficient preparation of 2,3-dihydroquinazolin−4(1H)-one derivatives with excellent yield in aqueous media. Reverse zinc oxide micelles catalyzed the reactions efficiently and selectively as the hallow nanoreactor. Moreover, the catalyst was reusable without significant loss of catalytic efficiency. The notable advantages of the procedure are high yields and mild reaction conditions, simple operation, nonchromatographic purification, environmentally friendly and good versatile substrates.

Green Synthesis of Zinc Oxide Nanoparticles Using Aqueous Extract of Deverra tortuosa and their Cytotoxic Activities

In recent years, there is a growing interest towards the green synthesis of metal nanoparticles, particularly from plants; however, yet no published study on the synthesis of ZnO.NPs using the Deverra tortuosa extract. Through this study, zinc oxide nanoparticles (ZnO.NPs) have been synthesized based on using the environmentally benign extract of the aerial parts of D. tortuosa as a reducing and capping agent. ZnO.NPs synthesis was confirmed using UV-Visible (UV-Vis) spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD) and High Resolution-Transmission Electron Microscope (HR-TEM). The qualitative and quantitative analyses of plant extract were done. The potential anticancer activity was in vitro investigated against two cancer cell lines (human colon adenocarcinoma "Caco-2" and human lung adenocarcinoma "A549") compared to their activities on the human lung fibroblast cell line (WI38) using the MTT assay. Both the aqueous extract and ZnO.NPs showed a remarkable selective cytotoxicity against the two examined cancer cell lines.

Zinc oxide nanoparticles for therapeutic purposes in cancer medicine

Zinc oxide nanoparticles are characterized by a good biocompatibility while providing a versatile potential as innovative therapeutic agents in cancer medicine.

Near Infrared-Activated Dye-Linked ZnO Nanoparticles Release Reactive Oxygen Species for Potential Use in Photodynamic Therapy

Novel dye-linked zinc oxide nanoparticles (NPs) hold potential as photosensitizers for biomedical applications due to their excellent thermal- and photo-stability. The particles produced reactive oxygen species (ROS) upon irradiation with 850 nm near infrared (NIR) light in a concentration- and time-dependent manner. Upon irradiation, ROS detected in vitro in human umbilical vein endothelial cells (HUVEC) and human carcinoma MCF7 cells positively correlated with particle concentration and interestingly, ROS detected in MCF7 was higher than in HUVEC. Preferential cytotoxicity was also exhibited by the NPs as cell killing was higher in MCF7 than in HUVEC. In the absence of irradiation, dye-linked ZnO particles minimally affected the viability of cell (HUVEC) at low concentrations (<30 μg/mL), but viability significantly decreased at higher particle concentrations, suggesting a need for particle surface modification with poly (ethylene glycol) (PEG) for improved biocompatibility. The presence of PEG on particles after dialysis was indicated by an increase in size, an increase in zeta potential towards neutral, and spectroscopy results. Cell viability was improved in the absence of irradiation when cells were exposed to PEG-coated, dye-linked ZnO particles compared to non-surface modified particles. The present study shows that there is potential for biological application of dye-linked ZnO particles in photodynamic therapy.

Cellular Stemness Maintenance of Human Adipose-Derived Stem Cells on ZnO Nanorod Arrays

Ever-growing tissue regeneration and other stem cell therapies cause pressing need for large population of self-renewable stem cells. However, stem cells gradually lose their stemness after long-term in vitro cultivation. In this study, a ZnO nanorod (ZnO NR) array is used to maintain the stemness of human adipose-derived stem cells (hADSCs). The results prove that after culturing hADSCs on ZnO NRs for 3 weeks, the stemness genes and protein expression level are higher than that on culture plates and ZnO film. ZnO NRs can maintain stemness of hADSCs without inhibiting the cell proliferation and oriented differentiation capabilities. KLF4 (Kruppel-like factor 4) is a Zn²⁺ -binding gene that plays a vital role in cell proliferation and differentiation. Sustained Zn²⁺ release and the increased expression of KLF4 can be detected, suggesting that ZnO NRs have efficiently released Zn²⁺ for stemness maintenance. Taken together, the nanotopography of ZnO NRs and the Zn²⁺ release synergistically facilitate stemness maintenance. This study has provided a powerful tool for directing cell fate, maintaining stemness, and realizing the expansion of stem cells in vitro, which will open a new route for the manufacture of large populations of stem cells and fulfilling the growing demand for the cell therapy market.

Preparation and Evaluation of the ZnO NP-Ampicillin/Sulbactam Nanoantibiotic: Optimization of Formulation Variables Using RSM Coupled GA Method and Antibacterial Activities

Nanoparticles (NPs) possessing antibacterial activity represent an effective way of overcoming bacterial resistance. In the present work, we report a novel formulation of a nanoantibiotic formed using Ampicillin/sulbactam (Ams) and a zinc oxide nanoparticle (ZnO NP). 'ZnO NP-Ams' nanoantibiotic formulation is optimized using response surface methodology coupled genetic algorithm approach. The optimized formulation of nanoantibiotic (ZnO NP: 49.9 μg/mL; Ams: 33.6 μg/mL; incubation time: 27 h) demonstrated 15% enhanced activity compared to the unoptimized formulation against K. pneumoniae. The reactive oxygen species (ROS) generation was directly proportional to the interaction time of nanoantibiotic and K. pneumoniae after the initial lag phase of ~18 h as evident from 2'-7'-Dichlorodihydrofluorescein diacetate assay. A low minimum inhibitory concentration (6.25 μg/mL) of nanoantibiotic formulation reveals that even a low concentration of nanoantibiotic can prove to be effective against K. pneumoniae. The importance of nanoantibiotic formulation is also evident by the fact that the 100 μg/mL of Ams and 25 µg of ZnO NP was required individually to inhibit the growth of K. pneumonia, whereas only 6.25 μg/mL of optimized nanoantibiotic formulation (ZnO NP and Ams in the ratio of 49.9: 33.6 in μg/mL and conjugation time of 27 h) was needed for the same.

Hyperthermia, Cytotoxicity, and Cellular Uptake Properties of Manganese and Zinc Ferrite Magnetic Nanoparticles Synthesized by a Polyol-Mediated Process

Manganese and zinc ferrite magnetic nanoparticles (MNPs) were successfully synthesizedusing the polyol method in ethylene glycol and were found to have high saturation magnetizationvalues (90-95 emu/g at 4 K) when formed by ~30-nm crystallites assembled in an ~80-nm multicorestructure. Hyperthermia data revealed a sigmoidal dependence of the specific absorption rate (SAR)on the alternating magnetic field (AMF) amplitude, with remarkable saturation SAR values in waterof ~1200 W/gFe+Mn and ~800 W/gFe+Zn for the Mn and Zn ferrites, respectively. The immobilizationof the MNPs in a solid matrix reduced the maximum SAR values by ~300 W/gFe+Mn, Zn for bothferrites. The alignment of the MNPs in a uniform static magnetic field, before their immobilizationin a solid matrix, significantly increased their heating performance. Toxicity assays performed infour cell lines revealed a lower toxicity for the Mn ferrites, while in the case of the Zn ferrites, only~50% of cells were viable upon their incubation for 24 h with 0.2 mg/mL of MNPs. Cellular uptakeexperiments revealed that both MNPs entered the cells in a time-dependent manner, as they werefound initially in endosomes and later in the cytosol. All of the studied cell lines were more sensitiveto the ZnFe2O4 MNPs.

Defect Engineering of ZnO Nanoparticles for Bioimaging Applications

Many promising attributes of ZnO nanoparticles (nZnO) have led to their utilization in numerous electronic devices and biomedical technologies. nZnO fabrication methods can create a variety of intrinsic defects that modulate the properties of nZnO, which can be exploited for various purposes. Here we developed a new synthesis procedure that controls certain defects in pure nZnO that are theorized to contribute to the n-type conductivity of the material. Interestingly, this procedure created defects that reduced the nanoparticle band gap to ∼3.1 eV and generated strong emissions in the violet to blue region while minimizing the defects responsible for the more commonly observed broad green emissions. Several characterization techniques including thermogravimetric analysis, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, Raman, photoluminescence, and inductively coupled plasma mass spectrometry were employed to verify the sample purity, assess how modifications in the synthesis procedure affect the various defects states, and understand how these alterations impact the physical properties. Since the band gap significantly decreased and a relatively narrow visible emissions band was created by these defects, we investigated utilizing these new nZnO for bioimaging applications using traditional fluorescent microscopy techniques. Although most nZnO generally require UV excitation sources to produce emissions, we demonstrate that reducing the band gap allows for a 405 nm laser to sufficiently excite the nanoparticles to detect their emissions during live-cell imaging experiments using a confocal microscope. This work lays the foundation for the use of these new nZnO in various bioimaging applications and enables researchers to investigate the interactions of pure nZnO with cells through fluorescence-based imaging techniques.

Key Role of Microtubule and Its Acetylation in a Zinc Oxide Nanoparticle-Mediated Lysosome-Autophagy System

Autophagy is a biological process that has attracted considerable attention as a target for novel therapeutics. Recently, nanomaterials (NMs) have been reported to modulate autophagy, which makes them potential agents for the treatment of autophagy-related diseases. In this study, zinc oxide nanoparticles (ZNPs) are utilized to evaluate NM-induced autophagy and debate the mechanisms involved. It is found that ZNPs undergo pH-dependent ion shedding and that intracellular zinc ions (Zn²⁺ ) play a crucial role in autophagy. Autophagy is activated with ZNPs treatment, which is inhibited after Zn²⁺ sequestration via ethylenediamine tetra-acetic acid. Lysosome-based autophagic degradation is halted after ZNPs treatment for more than 3 h and is accompanied by blockage of lysophagy, which renews impaired lysosomes. Furthermore, the microtubule (MT) system participates in ZNP-induced lysosome-autophagy system changes, especially in the fusion between autophagosomes and lysosomes. MT acetylation is helpful for protecting from ZNP-induced MT disruption, and it promotes the autophagic degradation process. In conclusion, this study provides valuable information on NM-induced lysosome-autophagy system changes, particularly with respect to the role of lysophagy and the MT system, which point to some attractive targets for the design of engineered nanoparticles.

Size-dependent cytotoxicity study of ZnO nanoparticles in HepG2 cells

Zinc oxide (ZnO) nanoparticles (NPs) are widely used in daily life. However, common utilization of ZnO NPs results in increases in environmental release, and their health hazards have attracted extensive attention. To investigate the cytotoxicity of ZnO NPs and their mechanism in HepG2 cells, a comprehensive analytical system was developed. The internalization, cytotoxic mechanism, death mechanism and elimination behavior of three sizes of ZnO NPs were studied by electrothermal vaporization (ETV)-inductively coupled plasma mass spectrometry (ICP-MS), MTT assays, GSH measurements, ROS measurements and analyses of apoptosis and gene expression. The size-, dose- and time-dependent characteristics of ZnO NPs were determined, and the metabolism of ZnO NPs in cells was discussed. The cytotoxicity of ZnO NPs was confirmed to depend on both the size and concentration and was attributed to the release of Zn²⁺, induction of oxidative stress and inflammatory response; the death mode of HepG2 cells incubated with ZnO NPs was necrotic rather than programmed cell death.