Hydrophilic ZnO Nanoparticles@Calcium Alginate Composite for Water Purification

The effectiveness of gliding arc discharge plasma in sterilizing artificial seawater contaminated with Vibrio parahaemolyticus

The rapid proliferation of the halophilic pathogen Vibrio parahaemolyticus poses a severe health hazard to halobios and significantly impedes intensive mariculture. This study aimed to evaluate the potential application of gliding arc discharge plasma (GADP) to control the infection of Vibrio parahaemolyticus in mariculture. This study investigated the inactivation ability of GADP against Vibrio parahaemolyticus in artificial seawater (ASW), changes in the water quality of GADP-treated ASW, and possible inactivation mechanisms of GADP against Vibrio parahaemolyticus in ASW. The results indicate that GADP effectively inactivated Vibrio parahaemolyticus in ASW. As the volume of ASW increased, the time required for GADP sterilization also increased. However, the complete sterilization of 5000 mL of ASW containing Vibrio parahaemolyticus of approximately 1.0 × 104 CFU/mL was achieved within 20 min. Water quality tests of the GADP-treated ASW demonstrated that there were no significant changes in salinity or temperature when Vibrio parahaemolyticus (1.0 ×104 CFU/mL) was completely inactivated. In contrast to the acidification observed in plasma-activated water (PAW) in most studies, the pH of ASW did not decrease after treatment with GADP. The H2O2 concentration in the GADP-treated ASW decreased after post-treatment. The NO2-concentration in the GADP-treated ASW remained unchanged after post-treatment. Further analysis revealed that GADP induced oxidative stress in Vibrio parahaemolyticus, which increased cell membrane permeability and intracellular ROS levels of Vibrio parahaemolyticus. This study provides a viable solution for infection with the halophilic pathogen Vibrio parahaemolyticus and demonstrates the potential of GADP in mariculture.

Engineering Sizable and Broad-Spectrum Antibacterial Fabrics through Hydrogen Bonding Interaction and Electrostatic Interaction

Long-lasting and highly efficient antibacterial fabrics play a key role in public health occurrences caused by bacterial and viral infections. However, the production of antibacterial fabrics with a large size, highly efficient, and broad-spectrum antibacterial performance remains a great challenge due to the complex processes. Herein, we demonstrate sizable and highly efficient antibacterial fabrics through hydrogen bonding interaction and electrostatic interaction between surface groups of ZnO nanoparticles and fabric fibers. The production process can be carried out at room temperature and achieve a production rate of 300 × 1 m2 within 1 h. Under both visible light and dark conditions, the bactericidal rate against Gram-positive (S. aureus), Gram-negative (E. coli), and multidrug-resistant (MRSA) bacteria can reach an impressive 99.99%. Furthermore, the fabricated ZnO nanoparticle-decorated antibacterial fabrics (ZnO@fabric) show high stability and long-lasting antibacterial performance, making them easy to develop into variable antibacterial blocks for protection suits.

Antibacterial Carbon Dots: Mechanisms, Design, and Applications

The increase in antibiotic resistance promotes the situation of developing new antibiotics at the forefront, while the development of non-antibiotic pharmaceuticals is equally significant. In the post-antibiotic era, nanomaterials with high antibacterial efficiency and no drug resistance make them attractive candidates for antibacterial materials. Carbon dots (CDs), as a kind of carbon-based zero-dimensional nanomaterial, are attracting much attention for their multifunctional properties. The abundant surface states, tunable photoexcited states, and excellent photo-electron transfer properties make sterilization of CDs feasible and are gradually emerging in the antibacterial field. This review provides comprehensive insights into the recent development of CDs in the antibacterial field. The topics include mechanisms, design, and optimization processes, and their potential practical applications are also highlighted, such as treatment of bacterial infections, against bacterial biofilms, antibacterial surfaces, food preservation, and bacteria imaging and detection. Meanwhile, the challenges and outlook of CDs in the antibacterial field are discussed and proposed.

Hydrophilic ZnO/C nanocomposites with superior adsorption, photocatalytic, and photo-enhanced antibacterial properties for synergistic water purification

Owing to the numerous potential applications of ZnO nanomaterials, the development of ZnO-based nanocomposites has become of great scientific interest in various fields. In this paper, we are reporting the fabrication of a series of ZnO/C nanocomposites through a simple "one-pot" calcination method under three different temperatures, 500 ℃, 600 ℃, and 700 ℃, with samples labeled as ZnO/C-500, -600, and -700, respectively. All samples exhibited adsorption capabilities and photon-activated catalytic and antibacterial properties, with the ZnO/C-700 sample showing superior performance among the three. The carbonaceous material in ZnO/C is key to expanding the optical absorption range and improving the charge separation efficiency of ZnO. The remarkable adsorption property of the ZnO/C-700 sample was demonstrated using Congo red dye, and is credited to its good hydrophilicity. It was also found to exhibit the most notable photocatalysis effect due to its high charge transfer efficiency. The hydrophilic ZnO/C-700 sample was also examined for antibacterial effects both in vitro (against Escherichia coli and Staphylococcus aureus) and in vivo (against MSRA-infected rat wound model), and it was observed to exhibit synergistic killing performance under visible-light irradiation. A possible cleaning mechanism is proposed on the basis of our experimental results. Overall, this work presents a facile way of synthesizing ZnO/C nanocomposites with outstanding adsorption, photocatalysis, and antibacterial properties for the efficient treatment of organic and bacterial contaminants in wastewater.

3D ZnO/Activated Carbon Alginate Beads for the Removal of Antibiotic-Resistant Bacteria and Antibiotic Resistance Genes

The worldwide prevalence of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) have become one of the most urgent issues for public health. Thus, it is critical to explore more sustainable methods with less toxicity for the long-term removal of both ARB and ARGs. In this study, we fabricated a novel material by encapsulating zinc oxide (ZnO) nanoflowers and activated carbon (AC) in an alginate biopolymer. When the dosage of ZnO was 1.0 g (≈2 g/L), the composite beads exhibited higher removal efficiency and a slight release of Zn²⁺ in water treatment. Fixed bed column experiments demonstrated that ZnO/AC alginate beads had excellent removal capacities. When the flow rate was 1 mL/min, and the initial concentration was 10⁷ CFU/mL, the removal efficiency of ARB was 5.69-log, and the absolute abundance of ARGs was decreased by 2.44-2.74-log. Moreover, the mechanism demonstrated that ZnO significantly caused cell lysis, cytoplasmic leakage, and the increase of reactive oxygen species induced subsequent oxidative stress state. These findings suggested that ZnO/AC alginate beads can be a promising material for removing ARB and ARGs from wastewater with eco-friendly and sustainable properties.

Multiphoton excited singlet/triplet mixed self-trapped exciton emission

Multiphoton excited luminescence is of paramount importance in the field of optical detection and biological photonics. Self-trapped exciton (STE) emission with self-absorption-free advantages provide a choice for multiphoton excited luminescence. Herein, multiphoton excited singlet/triplet mixed STE emission with a large full width at half-maximum (617 meV) and Stokes shift (1.29 eV) has been demonstrated in single-crystalline ZnO nanocrystals. Temperature dependent steady state, transient state and time-resolved electron spin resonance spectra demonstrate a mixture of singlet (63%) and triplet (37%) mixed STE emission, which contributes to a high photoluminescence quantum yield (60.5%). First-principles calculations suggest 48.34 meV energy per exciton stored by phonons in the distorted lattice of excited states, and 58 meV singlet-triplet splitting energy for the nanocrystals being consistent with the experimental measurements. The model clarifies long and controversial debates on ZnO emission in visible region, and the multiphoton excited singlet/triplet mixed STE emission is also observed.

Aptamer-Engineered Cu2O Nanocubes as a Surface-Modulated Catalytic Optical Sensor for Lung Cancer Cell Detection

Herein, fine and homogeneous Cu₂O nanocubes are synthesized and sensitized with a hairpin-structured AS1411 aptamer for the establishment of a biosensor for lung cancer cell detection. The Apt-Cu₂O nanocubes feature a recognition function in identifying a cancer-associated surface nucleolin protein. The intrinsic reduction catalytic ability is also confirmed by the use of two benchmark substrates, methylene blue (MB) and 4-nitrophenol (4-NP). The aptamer grafting on Apt-Cu₂O nanocubes is able to greatly prevent nonspecific-protein binding and to show specificity toward the nucleolin protein. The specific binding resulting from nucleolin protein leads to less exposure of the active area of the Apt-Cu₂O nanocubes, so the catalytic ability of Apt-Cu₂O nanocubes is thus diminished. The modulated catalytic ability led to less generation of the reduced 4-AP product, and the change in absorption of 4-AP allows the quantification of the nucleolin protein with a detection limit of 0.47 nM. The as-developed biosensor is applied to the detection of nucleolin-overexpressed A549 lung cancer cells, presenting a sensitive detection limit down to 20 cells. This may be ascribed to the clustering of surface nucleolin protein in a lipid raft membrane of cancer cells, as evidenced by a notable binding of Apt-Cu₂O nanocubes on the cancer cell surface. Real human serum samples spiked with cancer cells were also investigated, and a recovery rate of 87 ± 2.4% for 20 extracted cells validates the surface-modulated Apt-Cu₂O nanocubes-based catalytic optical biosensor as a promising tool for the detection of circulating tumor cells. The establishment of the Apt-Cu₂O nanocubes may allow for further studies on their use as a potential theranostics tool for cancer therapy.

Augmented antibacterial mechanism of ZnO nanoparticles by labyrinthian-channel configuration of maize-stalk carbohydrate columns and sustainable strategy for water decontamination

Zinc oxide nanoparticles (ZnO NPs) as a broad-spectrum germicide in environmental remediation applications, is hindered by mild toxicity to organisms during water sterilization. To solve this dilemma, this work provided an eco-benign approach to utilize maize stalk with natural labyrinthine-channel configuration simultaneously acting as microbe trap and bactericide carrier to arouse bactericidal response of ZnO NPs. The preparation comprises in-situ growing ZnO NPs, accompanied by nanoscale delignification, leading to formed carbohydrate complex retaining the intricately porous structure of the stalk. Assembled by maize-stalk carbohydrate (MSC) composites with 9 short composites in serial, the elimination of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) reached up 6.7 and 4.8 orders of magnitude, respectively. Labyrinth-framework MSC provided favorable sites for fusiform flower-like ZnO NPs to strongly adsorb (adsorption energy 5.5-11.7 eV) phosphoryl-involved biomacromolecules of bacterial envelops, causing generation of stable Zn-P and Zn-O(H), then cell incompleteness, cellular redox imbalance and DNA damage. Breakthrough analysis exposed the MSC/ZnO-filter possessing remarkable features of antibacterial exhaustion rate (~ 1.06 g/L) and capacity (~ 9.6 × 10⁹ CFU/g) which were comparable with Ag-based composites. As evaluated by the logistic and Gompertz models, the filters effectively sterilized 0.97-10 L of environmental waters to meet the requirements of drinking water.

A biofilm microenvironment-responsive one-for-all bactericidal nanoplatform for photothermal-augmented multimodal synergistic therapy of pathogenic bacterial biofilm infection

We rationally construct a biofilm microenvironment-responsive bactericidal nanoplatform (ZnPMp) consisting of ZnO core, a Fe3+-doped polydopamine coating and methylene blue (MB) payload for combined CT/CDT/PTT/PDT multi-mode antibacterial therapy.

Preparation of eugenol nanoemulsions for antibacterial activities

Eugenol is a versatile plant essential oil, but its high volatility and low water solubility greatly limit its application. Accordingly, this study prepared eugenol nanoemulsions by a high-speed shearing technique. Through visual inspection and a series of characterizations, including dynamic light scattering, and confocal laser scanning microscopy, the optimized formula was determined to be 5% (w/w) oil phase (eugenol) and 8% (w/w) surfactant (Tween-80), and the optimized shearing time was 5 min. The optimized nanoemulsion had good stability, small droplets (85 nm), and uniform distribution. At a concentration of 0.02 mg μL⁻¹, the nanoemulsion showed strong inhibition against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Scanning electron microscopy (SEM) images showed severe deformation and membrane rupture of both bacteria treated by the nanoemulsion. This result was further confirmed by the leakage of proteins in both bacteria after treatment. The results of reactive oxygen species (ROS) and malondialdehyde (MDA) measurements indicated that the increased levels of ROS in both bacteria treated by the nanoemulsion triggered lipid peroxidation, thus increasing the MDA levels, ultimately causing changes in cell membrane permeability and disruption of the membrane structure. In addition, the nanoemulsion had a small effect on the proliferation and apoptosis of hepatocytes (L02) and lung cells (BEAS-2B), indicating its good biocompatibility. In this study, we developed a novel eugenol nanoemulsion with high stability and good biological activity, which may provide a promising and effective method for wound treatment in the healthcare area.

We developed a novel eugenol nanoemulsion with high stability and good biological activity, which may provide a promising and effective method for wound treatment in the healthcare area.

Copper hydroxide nanosheets-assembled nanofibrous membranes for anti-biofouling water disinfection

Copper hydroxide (Cu(OH)₂) has been elected as a newly-emerging green disinfectant to deal with membrane biofouling in the treatment of bacteria-contaminated water; however, the decoration strategy of it with the granular form on membrane substrates limits the practical application. Here a novel surface-confined methodology was proposed for preparing freestanding Cu(OH)₂ nanosheet-assembled nanofibrous membranes (CNNMs) with the anti-biofouling property via the in-suit coprecipitation and heat-induced growth method. The vertically aligned Cu(OH)₂ nanosheets were in-suit rooted on the surface of the nanofiber scaffold with high binding fastness. The acquired CNNMs possess comprehensive performances of high porosity, prominent mechanical strength, fatigue resistance, and superior bactericidal efficiency of 99.999%, which endowed the CNNMs ultrahigh filtration fluxes (24000 L m^-2 h^-1) and durability to disinfect bacteria-containing water effectively. This facile strategy may throw light on manufacturing novel inorganic nanosheet-rooted nanofibrous membranes for water disinfection and public health.

NanoZnO-modified titanium implants for enhanced anti-bacterial activity, osteogenesis and corrosion resistance

Titanium (Ti) implants are widely used in dentistry and orthopedics owing to their excellent corrosion resistance, biocompatibility, and mechanical properties, which have gained increasing attention from the viewpoints of fundamental research and practical applications. Also, numerous studies have been carried out to fine-tune the micro/nanostructures of Ti and/or incorporate chemical elements to improve overall implant performance. Zinc oxide nanoparticles (nano-ZnO) are well-known for their good antibacterial properties and low cytotoxicity along with their ability to synergize with a variety of substances, which have received increasingly widespread attention as biomodification materials for implants. In this review, we summarize recent research progress on nano-ZnO modified Ti-implants. Their preparation methods of nano-ZnO modified Ti-implants are introduced, followed by a further presentation of the antibacterial, osteogenic, and anti-corrosion properties of these implants. Finally, challenges and future opportunities for nano-ZnO modified Ti-implants are proposed.

Ratiometric fluorescence sensor based on europium-grafted ZnO quantum dots for visual and colorimetric detection of tetracycline

An europium functionalized ZnO quantum dots (QDs) ratiometric fluorescent nanoprobe is designed to establish a real time, on-site visual, and highly sensitive probe method for tetracycline (TC). The yellow-emitting ZnO QDs serves as the internal reference, while the Eu³⁺ chelated on the surface of ZnO QDs is used as the signal reporting unit. This nanoprobe exhibits rapid response, excellent selectivity, and high sensitivity with a detection limit of 4 nM in detecting the levels of TC. In addition, fluorescence of the nanoprobe can change from yellow to red as the concentration of TC increases. Thus, naked eye detection of TC was realized using the test paper processed by nanoprobe, followed by RGB value analysis function on the mobile phone APP.

Multifunctional Applications of Blow-Spinning Setaria viridis Structured Fibrous Membranes in Water Purification

With increasing water pollution and human health problems caused by oily wastewater, the fabrication of oil-water separation materials has become an urgent task. However, most of the reported materials have a single function and poor performance. In this paper, a multifunctional zinc oxide/polyaniline/polyacrylonitrile (ZnO/PANI/PAN) nanofibrous membrane with needle-like ZnO nanorods was prepared by in situ synthesis of PANI and a hydrothermal reaction on a highly stable self-standing PAN blow-spinning fibrous membrane. Due to the electronic synergistic effect of ZnO and PANI, the fibrous membrane exhibits excellent antibacterial activity and visible-light degradation ability of organic dyes. Moreover, the micro-/nanosized pores of the ZnO/PANI/PAN fibrous membranes also guarantee its excellent emulsion separation performance, including an ultrahigh surfactant-free emulsion permeate flux (∼8597.40 L/(m² h)), ultrahigh surfactant-stabilized emulsion permeate flux (∼2253.50 L/(m² h)), and excellent separation efficiency (above 99%). Furthermore, the composite membrane maintains stable underwater superoleophobicity and hydrophilicity under adverse conditions, shows good biological safety, and is harmless to the water environment. These excellent properties endow the ZnO/PANI/PAN nanofibrous membranes with great potential in treating oily wastewater.

Mussel-inspired surface functionalization of polyamide microfiltration membrane with zwitterionic silver nanoparticles for efficient anti-biofouling water disinfection

Mature microfiltration (MF) membrane is a low-cost, effective, and promising technology to provide affordable purified water for people living in developing countries. However, the lack of disinfection ability and inherent membrane fouling problems have seriously restricted the large-scale application of conventional MF treatment system in producing safe drinking water. In this work, zwitterionic silver nanoparticles (AgNPs) with surface modification of poly(carboxybetaine acrylate-co-dopamine methacryamide) (PCBDA) copolymers were robustly immobilized onto commercial polyamide MF membrane via mussel-inspired chemistry for water disinfection. The designed microfiltration membrane, named as PCBDA@AgNPs-MF, exhibited integrated properties of high and stable payload of AgNPs, broad-spectrum anti-adhesive and antimicrobial activities, and easy removal of inactivated microbial cells from membrane surface. Ascribing to the synergetic effect of anti-adhesive and antimicrobial features brought by zwitterionic PCBDA@AgNPs, the biofilms growth on polyamide membrane surface was significantly inhibited, which showed potential access to achieve long-term biofouling resistance and maintain water flux for conventional MF membrane. As water disinfection device, these attributes enabled PCBDA@AgNPs-MF to effectively disinfect the model and natural bacteria-contaminated water.

Robust immobilization of anionic silver nanoparticles on cellulose filter paper toward a low-cost point-of-use water disinfection system with improved anti-biofouling properties

Silver nanoparticle (AgNP)-decorated cellulose filter paper (FP), a low-cost point-of-use (POU) water disinfection system, can supply affordable and safe drinking water for people in desperate need, especially in rural areas in developing countries. However, owing to the unstable immobilization of AgNPs, silver can leach into the treated drinking water from the FP and exceed the World Health Organization (WHO) drinking water limit (<100 μg L-1), which is a potential threat to both human health and the environment. In this work, in order to robustly immobilize anionic silver nanoparticles (GA@AgNPs), we facilely prepared lipoic acid-modified cellulose filter paper (LA-FP), in which GA@AgNPs were robustly immobilized onto filter paper (GA@AgNPs-LA-FP) by strong chelation via the disulfide bond of LA with the surface of the silver nanoparticles. GA@AgNPs-LA-FP exhibited both excellent bacterial anti-adhesion activity and strong bactericidal activity, which can synergistically mitigate biofouling by inhibiting biofilm formation on the paper surface. Moreover, employed as a gravity-driven bactericidal filter, the GA@AgNPs-LA-FP membrane treated 100 mL of river water within 10 min, and the resulting water quality met the WHO drinking water standards, indicating this material's practical application for POU water disinfection.

A journey to the world of fascinating ZnO nanocomposites made of chitosan, starch, cellulose, and other biopolymers: Progress in recent achievements in eco-friendly food packaging, biomedical, and water remediation technologies

Green chemistry or in other words "green world" is referred to a sustainable environment using biocompatible, biodegradable, renewable, economical, and simple materials, and methods. Without any exaggeration, the exceptional chemical and physical properties of ZnO bionanocomposites beside various utilizations, make it vital materials in research and green chemistry field. Biocompatible ZnO nanoparticles with fascinating antimicrobial, physicochemical, as well as photocatalytic performance could be applied as a prominent candidate to reinforce diverse biopolymer matrixes, for instance, chitosan, starch, cellulose, gelatin, alginate, poly(hydroxyalkanoates), carrageenan, and so on. With a combination of advantageous properties of these materials, they could be illustrated specific utilizations in different areas. In this regard, the following context focuses on highlighting the recent achievements of this category of material on three important and widely used scopes: eco-friendly food packaging, biomedical specially wound dressings, and water remediation technologies.