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ZnO/Ag hollow particles were synthesized via a one-step spray pyrolysis method for enhanced antibacterial activity and wound healing applications. The hollow structure and uniform distribution of Ag nanoparticles within the ZnO matrix were confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). UV-Vis spectroscopy and Tauc plot analysis revealed a reduction in the bandgap, attributed to the surface plasmon resonance (SPR) of Ag, improving light absorption in the visible range. Antibacterial tests against Escherichia coli ( E. coli ) and methicillin-resistant Staphylococcus aureus (MRSA) showed that ZnO/Ag composites exhibited significantly enhanced antibacterial efficacy under visible light compared to pure ZnO. The antibacterial mechanism was investigated using electron paramagnetic resonance (EPR) spectroscopy, which confirmed the generation of reactive oxygen species (˙OH and ˙O 2 - ). These results indicate that ZnO/Ag hollow composites are promising candidates for antibacterial coatings and wound healing applications, especially under visible light activation.

Contemporary wound dressings lack antibacterial properties, exhibit a low water vapour transmission rate, and demonstrate inadequate porosity. In order to overcome these limitations, scientists have employed water hyacinth to produce carboxymethyl cellulose (CMC). CMC/PVP nanocomposite films containing biogenic zinc oxide nanoparticles (nZnOs) were synthesised using cost effective solution-casting technique. As the proportion of nZnOs in the film increased, swelling and water permeability decreased, whereas mechanical stability improved. Dynamic light scattering testing and transmission electron microscopy confirmed that the particle size was around 50.7 nm. Field emission scanning electron microscopy (FESEM) images showed that nZnOs were distributed uniformly in the polymer matrix. Cell viability against Vero cells was greater than 94%, and a substantial zone of inhibition against S. aureus and E. coli bacteria was observed. Wounds of albino mice were treated with CMC/PVP and CMC/PVP/nZnO (6%) nanocomposite hydrogels and healed in 20 and 12 days, respectively, as demonstrated by wound healing assay and histological staining. In vitro and in vivo studies revealed that the novel nanocomposite hydrogels exhibit improved cell viability and wound healing features. Therefore, they could be exploited as promising skin wound dressing materials.

The accumulation of agricultural and industrial residues inevitably contributes to environmental pollution. Thus, several scientific investigations have been conducted to overcome this problem and to add an economic value proposition. Unlike typical sugarcane bagasse applications, this work presents a novel application of sugarcane bagasse waste in a green synthesis approach for forming zinc oxide nanoparticles (ZnO-NPs). This work opens the door to studying the potential of sugarcane bagasse in a green synthesis orientation. Phytochemical assessment of the aqueous extract of sugarcane bagasse waste was conducted by studying total flavonoid content, total phenolic content, and antioxidant assays. ZnO-NPs were synthesized using the aqueous sugarcane bagasse extract (ASCBE) with a 96% yield. To obtain 99.7% pure ZnO-NPs, nanoparticles were calcined at 550 °C to remove any remaining plant extract residues. The purity and yield of the produced and modified ZnO-NPs were studied. The initially produced and modified ZnO-NPs were characterized using XRD, FT-IR, UV, TEM, TGA, and PL and to determine the necessity of the calcination step. A detailed proposed mechanism for the formation of ZnO-NPs mediated by ASCBE was introduced. The ZnO-NPs were studied for their antibacterial, antifungal, and antiviral activities. The ZnO-NPs before calcination were found to exhibit more potent antimicrobial activity against both P. aeruginosa and A. niger compared to the calcined ZnO-NPs. In addition, molecular docking analysis revealed that the ZnO-NPs had the strongest binding affinity towards the P. aeruginosa RhlG/NADP active-site complex and the crystal structure of Actibind, a T2 RNase of A. Niger . ZnO-NPs also showed promising binding interactions with viral targets, including the Herpes simplex virus type II protease and Influenza virus NS1 effector domain. Additionally, environmental and economic studies were achieved to relate the scientific study with daily life applications.

Micro/nanorobots (MNRs) hold great promise for various applications due to their capability to execute complex tasks in hard-to-reach micro/nano cavities. However, the developed magnetic MNRs, as marionettes of external magnetic fields, lack built-in intelligence for self-targeting, while chemotactic MNRs suffer from limited self-targeting range. Here, we demonstrate magnetic-chemotactic ZnO/Fe-Ag Janus microrobots (JMRs) capable of rapid, remote self-targeting for bacterial elimination. The JMRs utilize the magnetic Fe engine for coarse navigation from a distance, allowing for external control to swiftly guide them to the vicinity of a hidden/uncharted target that establishes a local chemical gradient ([CO 2 ] or [H + ] gradient). Once in proximity, the inherent chemotaxis of the JMRs takes over, the chemotactic engine enables them to autonomously accumulate at the target site along the chemical gradient in high precision. Upon reaching the target, the ZnO/Fe-Ag JMRs can release Zn 2+ and Ag + to eliminate bacteria residing there. The proposed strategy of integrating on-board chemotaxis with external magnetic field-driven propulsion paves the way for efficient precise therapies using MNRs, especially in targeted drug/energy delivery involving remote hidden or uncharted targets.

The repair of critical bone defects caused by various clinical conditions needs to be addressed urgently, and the regeneration of large bone defects depends on early vascularization. Therefore, enhanced vascularization of artificial bone grafts may be a promising strategy for the regeneration of critical-sized bone defects. Taking into account the importance of rapid angiogenesis during bone repair and the potential of piezoelectric stimulation in promoting bone regeneration, novel coaxial electrospun mats coupled with piezoelectric materials and angiogenic drugs were fabricated in this study using coaxial electrospinning technology, with a shell layer loaded with atorvastatin (AVT) and a core layer loaded with zinc oxide (ZnO). AVT was used as an angiogenesis inducer, and piezoelectric stimulation generated by the zinc oxide was used as an osteogenesis enhancer. The multifunctional mats were characterized in terms of morphology, core-shell structure, piezoelectric properties, drug release, and mechanical properties, and their osteogenic and angiogenic capabilities were validated in vivo and ex vivo . The results revealed that the coaxial electrospun mats exhibit a porous surface morphology and nanofibers with a core-shell structure, and the piezoelectricity of the mats improved with increasing ZnO content. Excellent biocompatibility, hydrophilicity and cell adhesion were observed in the multifunctional mats. Early and rapid release of AVT in the fibrous shell layer of the mat promoted angiogenesis in human umbilical vascular endothelial cells (HUVECs), whereas ZnO in the fibrous core layer harvested bioenergy and converted it into electrical energy to enhance osteogenic differentiation of rat bone mesenchymal stem cells (BMSCs), and both modalities synergistically promoted osteogenesis and angiogenesis. Furthermore, optimal bone regeneration was achieved in a model of critical bone defects in the rat mandible. This osteogenesis-promoting effect was induced by electrical stimulation via activation of the calcium signaling pathway. This multifunctional mat coupling piezoelectric stimulation and atorvastatin promotes angiogenesis and bone regeneration, and shows great potential in the treatment of large bone defects.

Formation of bacterial films on structural surfaces often leads to severe contamination of medical devices, hospital equipment, implant materials, etc. , and antimicrobial resistance of microorganisms has indeed become a global health issue. Therefore, effective therapies for controlling infectious and pathogenic bacteria are urgently needed. Being a promising active method for this purpose, surface acoustic waves (SAWs) have merits such as nanoscale earthquake-like vibration/agitation/radiation, acoustic streaming induced circulations, and localised acoustic heating effect in liquids. However, only a few studies have explored controlling bacterial growth and inactivation behaviour using SAWs. In this study, we proposed utilising piezoelectric thin film-based SAW devices on a silicon substrate for controlling bacterial growth and inactivation with and without using ZnO micro/nanostructures. Effects of SAW powers on bacterial growth for two types of bacteria, i.e. , E. coli and S. aureus , were evaluated. Varied concentrations of ZnO tetrapods were also added into the bacterial culture to study their effects and the combined antimicrobial effects along with SAW agitation. Our results showed that when the SAW power was below a threshold ( e.g. , about 2.55 W in this study), the bacterial growth was apparently enhanced, whereas the further increase of SAW power to a high power caused inactivation of bacteria. Combination of thin film SAWs with ZnO tetrapods led to significantly decreased growth or inactivation for both E. coli and S. aureus , revealing their effectiveness for antimicrobial treatment. Mechanisms and effects of SAW interactions with bacterial solutions and ZnO tetrapods have been systematically discussed.

A solvothermal method and the subsequent heat treatment process were developed to fabricate hollow ZnO particles with hierarchical pores on a large scale. The as-obtained hollow, porous ZnO microspheres with tunable sizes, high specific surface areas, pH sensitivity, antibacterial properties, and high adsorption capacities showed significant advantages for drug delivery. Sprayable hydrogels containing hollow, porous ZnO microspheres and curcumin nanoparticles (CNPs) were prepared to accelerate wound healing. The water-dispersed CNPs promoted both the migration of fibroblasts and angiogenesis and an aqueous solution of Pluronic F127 (a temperature-sensitive phase-change hydrogel material) was shown to be an effective choice for medical dressings. The experimental data suggest that hollow, porous ZnO microspheres can be loaded with additional CNPs to achieve continuous long-term therapeutic effects.

Despite enormous advancements in its management, cancer is the world's primary cause of mortality. Therefore, tremendous strides were made to produce intelligent theranostics with mitigated side effects and improved specificity and efficiency. Thus, we developed a pH-sensitive theranostic platform composed of dextran immobilized zinc oxide nanoparticles, loaded with doxorubicin and radiolabeled with the technetium-99m radionuclide ( 99m Tc-labelled DOX-loaded ZnO@dextran). The platform measured 11.5 nm in diameter with -12 mV zeta potential, 88% DOX loading efficiency and 98.5% radiolabeling efficiency. It showed DOX release in a pH-responsive manner, releasing 93.1% cumulatively at pH 5 but just 7% at pH 7.4. It showed improved intracellular uptake, which resulted in a high growth suppressive effect against MCF-7 cancer cells as compared to the free DOX. It boasted a 4 times lower IC 50 than DOX, indicating its significant anti-proliferative potential (0.14 and 0.55 μg ml -1 , respectively). The in vitro biological evaluation revealed that its molecular mode of anti-proliferative action included downregulating Cdk-2, which provoked G1/S cell cycle arrest, and upregulating both the intracellular ROS level and caspase-3, which induced apoptosis and necrosis. The in vivo experiments in Ehrlich-ascites carcinoma bearing mice demonstrated that DOX-loaded ZnO@dextran showed a considerable 4-fold increase in anti-tumor efficacy compared to DOX. Moreover, by utilizing the diagnostic radionuclide ( 99m Tc), the radiolabeled platform ( 99m Tc-labelled DOX-loaded ZnO@dextran) was in vivo monitored in tumor-bearing mice, revealing high tumor accumulation (14% ID g -1 at 1 h p.i.) and reduced uptake in non-target organs with a 17.5 T/NT ratio at 1 h p.i. Hence, 99m Tc-labelled DOX-loaded ZnO@dextran could be recommended as a rectified tumor-targeted theranostic platform.

Catalytic therapy based on nanozymes is promising for the treatment of bacterial infections. However, its therapeutic efficacy is usually restricted by the limited amount of hydrogen peroxide and the weak acidic environment in infected tissues. To solve these issues, we prepared polyvinyl alcohol (PVA)-polyacrylic acid (PAA)-iron oxide (Fe 3 O 4 )/polyvinyl alcohol (PVA)-zinc peroxide (ZnO 2 ) double-layer electrospun nanofibers (PPF/PZ NFs). In this design, PVA serves as the carrier for ZnO 2 nanoparticles (NPs), Fe 3 O 4 NPs, and PAA. The double-layer structure of nanofibers can spatially separate the PAA and ZnO 2 to avoid their reaction with each other during preparation and storage, while in the wet wound bed, PVA can dissolve and PAA can provide H + ions to promote the generation of hydrogen peroxide and subsequent conversion to hydroxyl radicals for bacteria killing. In vitro experimental results demonstrated that PPF/PZ NFs can reduce the methicillin-resistant Staphylococcus aureus by 3.1 log (99.92%). Moreover, PPF/PZ NFs can efficiently treat the bacterial infection in a mouse wound model and promote wound healing with negligible toxicity to animals, indicating their potential use as "plug-and-play" antibacterial wound dressings. This work provides a novel strategy for the construction of double-layer electrospun nanofibers as catalytic wound dressings with hydrogen peroxide/acid self-supplying properties for the efficient treatment of bacterial infections.

There is currently a great deal of interest in realizing localized surface plasmon resonances (LSPRs) in two distinct windows in the near-infrared (NIR) spectrum for in vivo biosensing and medical applications, the biological window (BW) I and II (BW I, 700-900 nm; BW II, 1000-1700 nm). This study aims to demonstrate that LSPRs of Ga-doped ZnO (GZO) core-silver (Ag) shell structures exhibit promising features for biological applications in the NIR BW I and II. Here, we study three different shapes for nanoshells: the core-shell nanosphere, nanorod, and nanodisk. In the calculation of the optical response of these nanoshells, an effective medium approach is first used to reduce the dielectric function of a nanoshell to that of an equivalent homogenous NP with an effective dielectric function. Then, the LSPR spectra of nanoshells are calculated using the modified long-wavelength approximation (MLWA), which corrects the polarizability of the equivalent NP as obtained by Gans theory. Through numerical investigations, we examine the impacts of the core and shell sizes of the proposed nanoshells as well as the medium refractive index on the position and line width of the plasmon resonance peaks. It is shown that the plasmon resonances of the three proposed nanoshells exhibit astonishing resonance tunability in the NIR region by varying their geometrical parameters. Specifically, the improved spectrum characteristics and tunability of its plasmon resonances make the GZO-Ag nanosphere a more viable platform for NIR applications than the spherical metal colloid. Furthermore, we demonstrate that the sensitivity and figure of merit (FOM) of the plasmon resonances may be significantly increased by using GZO-Ag nanorods and nanodisks in place of GZO-Ag nanospheres. It is found that the optical properties of the transverse plasmon resonance of the GZO-Ag nanodisk are superior to all plasmon resonances produced by the GZO-Ag nanorods and GZO-Ag nanospheres in terms of sensitivity and FOM. The FOM of the transverse plasmon mode of the GZO-Ag nanodisk is almost two orders of magnitude higher than that of the longitudinal and transverse plasmon modes of the GZO-Ag nanorod in BW I and BW II. And it is 1.5 and 2 times higher than the plasmon resonance FOM of GZO-Ag nanospheres in BW I and BW II, respectively.

The prostate-specific antigen (PSA) test is considered an important way for preoperative diagnosis and accurate screening of prostate cancer. Current antigen detection methods, including radioimmunoassay, enzyme-linked immunosorbent assay and microfluidic electrochemical detection, feature expensive equipment, long testing time and poor stability. Here, we propose a portable biosensor composed of electrolyte-gated amorphous indium gallium zinc oxide (a-IGZO) transistors with an extended gate, which can achieve real-time, instant PSA detection at a low operating voltage (<2 V) owing to the liquid-free ionic conductive elastomer (ICE) serving as the gate dielectric. The electric double layer (EDL) capacitance in ICE enhances the accumulation of carriers in the IGZO channel, leading to strong gate modulation, which enables the IGZO transistor to have a small subthreshold swing (<0.5 V dec -1 ) and a high on-state current (∼4 × 10 -4 A). The separate, biodegradable, and pluggable sensing pad, serving as an extended gate connected to the IGZO transistor, prevents contamination and depletion arising from direct contact with biomolecular buffers, enabling the IGZO transistor to maintain superior electronic performance for at least six months. The threshold voltage and channel current of the transistor exhibit excellent linear response to PSA molecule concentrations across five orders of magnitude ranging from 1 fg mL -1 to 10 pg mL -1 , with a detection limit of 400 ag mL -1 and a detection time of ∼5.1 s. The fabricated biosensors offer a point-of-care system for antigen detection, attesting the feasibility of the electrolyte-gated transistors in clinical screening, healthcare diagnostics and biological management.

Thin-film nano-architecting is a promising approach that controls the properties of nanoscale surfaces to increase their interdisciplinary applications in a variety of fields. In this context, zinc oxide (ZnO)-based various nano-architectures (0-3D) such as quantum dots, nanorods/nanotubes, nanothin films, tetrapods, nanoflowers, hollow structures, etc. have been extensively researched by the scientific community in the past decade. Owing to its unique surface charge transport properties, optoelectronic properties and reported biomedical applications, ZnO has been considered as one of the most important futuristic bio-nanomaterials. This review is focused on the design/synthesis and engineering of 0-3D nano-architecture ZnO-based thin films and coatings with tunable characteristics for multifunctional biomedical applications. Although ZnO has been extensively researched, ZnO thin films composed of 0-3D nanoarchitectures with promising thin film device bio-nanotechnology applications have rarely been reviewed. The current review focuses on important details about the technologies used to make ZnO-based thin films, as well as the customization of properties related to bioactivities, characterization, and device fabrication for modern biomedical uses that are relevant. It features biosensing, tissue engineering/wound healing, antibacterial, antiviral, and anticancer activity, as well as biomedical diagnosis and therapy with an emphasis on a better understanding of the mechanisms of action. Eventually, key issues, experimental parameters and factors, open challenges, etc. in thin film device fabrications and applications, and future prospects will be discussed, followed by a summary and conclusion.

In the present work, acidic (direct) and basic precipitation (indirect) methods were used to demonstrate the influence of the mode of precipitation on the structural properties of ZnO nanoparticles (NPs). Four samples of ZnO nanoparticles were prepared, two samples via each mode of precipitation. DZOa and IZOa were the aged samples prepared via acidic and basic precipitation methods, and DZOwa and IZOwa were processed without aging. Both precipitation processes were carried out without using any surfactant reagents. Zinc hydroxide precipitate, which was formed during the basic precipitation method, could be critical in deciding the properties of ZnO NPs, unlike zinc hydroxide formed during acidic precipitation. Aging of zinc hydroxide, synthesised by basic precipitation method for 48 hours was found to be an added advantage in controlling the properties of ZnO NPs. The influence of the mode of precipitation on the structural properties and antibacterial activity of ZnO NPs against Gram-positive and Gram-negative bacterial strains was tested. The antibacterial activity of all four ZnO NPs was analysed via zone of inhibition measurements at a concentration dose of 200 μg ml -1 . IZOa nanoparticles prepared using the basic precipitation method showed a higher antibacterial activity against three Gram-negative and one Gram-positive strains, namely, Klebsiella pneumoniae , Pseudomonas aeruginosa , Staphylococcus aureus , and Escherichia coli . DZOa nanoparticles synthesized through acidic precipitation showed relatively high antibacterial activity against Salmonella typhimurium , a Gram-negative strain. ZnO NPs prepared without aging, IZOwa and DZOwa, showed a higher antibacterial activity against E. coli and Bacillus sp. strains, respectively. All ZnO NPs were characterized via UV-visible, FTIR, XRD, and HRSEM techniques.

Dopamine (DA) and uric acid (UA), which are vital components in human metabolism, cause several health problems if they are present in altered concentrations; thus, the determination of DA and UA is essential in real samples using selective sensors. In the present study, graphite carbon paste electrodes (CPE) were fabricated using ZnO/carbon quantum dots (ZnO/CQDs) and employed as electrochemical sensors for the detection of DA and UA. These electrodes were fully characterized via different analytical techniques (XRD, SEM, TEM, XPS, and EDS). The electrochemical responses from the modified electrodes were evaluated using cyclic voltammetry, square wave voltammetry, and electrochemical impedance spectroscopy. The results showed that the present electrode has exhibited high sensitivity towards DA, recognizing even at low concentrations (0.12 μM), and no inference was observed in the presence of UA. The ZnO/CQD electrode was applied for the simultaneous detection of co-existing DA and UA in real human urine samples and the peak potential separation between DA and UA was found to be greatly associated with the synergistic effect originated from ZnO and CQDs. The limit of detection (LOD) of the electrode was analyzed, and compared with other commercially available electrodes. Thus, the ZnO/CQD electrode was used to detect DA and UA in real samples, such as Saccharomyces cerevisiae cells.

Recent studies have reported that nanoparticles (NPs) released into the aquatic environment may interact with persistent organic pollutants such as brominated flame retardants, whereas the environmental processes and toxicological impacts induced by such binary NPs require further specification. This study investigated the ultrastructural damage of Chlorella vulgaris triggered by exposure to zinc oxide (ZnO) NPs, tetrabromobisphenol A (TBBPA), ZnO-TBBPA, and ZnO-TBBPA-humic acid (HA), clarified the uptake and distribution of ZnO NPs in cells, and explored the physiological toxicity and tolerance mechanism. The results demonstrated that ZnO NPs induced irregular morphology in algal cells, and the disruption of the cellular ultrastructure by binary ZnO-TBBPA was also extremely severe due to the excessive uptake of ZnO NPs, which resulted in strong oxidative stress responses. In particular, the accumulation of reactive oxygen species further exacerbated the reduction of total chlorophyll content and algal density. Moreover, the cluster heat map and correlation analysis revealed that superoxide dismutase activity played a critical role in alleviating lipid peroxidation damage and enhancing the tolerance of algal cells to the stress of binary ZnO NPs. More notably, the existence of HA intensified the dispersion stability of NP suspensions and significantly mitigated the synergistic toxicity of binary ZnO-TBBPA. This study provides new insights into the environmental behavior and biological impacts of binary NPs in the natural environment.

We have investigated the interactions between a 5-aminolevulinic acid (ALA) drug and ZnO nanostructures including ZnO monolayers and ZnO nanotubes (ZnONTs) using density functional theory (DFT) calculations. In the context of the dispersion corrected Perdew-Burke-Ernzerhof (PBE) approach, the energetics, charge transfer, electronic structure and equilibrium geometries have been estimated. As ALA is adsorbed onto/into the ZnONTs and on the ZnO monolayer with interaction energies ( E int ) of -2.55/-2.75 eV and -2.51 eV, respectively, the calculated E int values and bonding distances (∼2 Å) reveal that the interaction type is chemisorption. The ZnO nanostructures showed promising performance in the ALA drug functionalization, taking into account the interaction energy values. The band gap almost remains unchanged for both of the substrates under consideration after ALA adsorption, and the semiconductor properties of the substrates are preserved, according to the analyzed density of states (DOSs) spectra. The interaction nature of the ALA-ZnO nanostructures according to the atom in molecule (AIM) analysis was found to be polar attraction with partial covalent bonding between O and Zn. Our DFT based molecular dynamic (MD) simulation results demonstrate that, in the aqueous solution, ALA moves toward the interior sidewall of the ZnONTs and ZnO nanosheet surface and binds to the Zn atom through its O (carbonyl/hydroxyl groups) and N atoms and the hydroxyl H atom was dissociated and binds to the O atom of the ZnO surface. However, in the case of ALA adsorption onto the outer surface of ZnONTs, only the O atoms of carbonyl groups bind to the Zn atom and the structure of the drug remains undestroyed during the adsorption. The current findings shed light on the polar drug adsorption/encapsulation behavior on/into ZnO nanostructures, which may encourage further use of ZnO-based nanomaterials in the field of drug delivery and bio-functionalized nanomaterials.

Cardiac troponin I (cTnI) is one of the structural subunits of cardiac troponin complexes and a significant biomarker of acute myocardial infarction (AMI). Therefore, a sensitive detection of cTnI in the early stages is of great significance. Here, a sensitive sandwiched electrochemiluminescence (ECL) immunosensor was built for the detection of cTnI, where molybdenum disulfide@cuprous oxide-silver nanoparticles (MoS 2 @Cu 2 O-Ag) immobilized cTnI the capture antibody (Ab 1 ), and cerium-doped zinc oxide@nitrogen-doped graphene quantum dots (Ce:ZnO@NGQDs) loaded the signal antibody (Ab 2 ). The MoS 2 @Cu 2 O-Ag nanoparticles not only indicated excellent electroconductivity and biocompatibility but also provided a large specific surface. Ce:ZnO as a co-reaction accelerator can convert the Ce 4+ ↔ Ce 3+ reaction and might increase the rate of electron exchange to accomplish signal enhancement. Under optimum conditions, the sensor possessed a wide linear range from 10 pg mL -1 to 100 ng mL -1 , and the LOD was 2.90 fg mL -1 (S/N = 3). In addition, the sensor plays a good role in serum detection, indicating that it has potential for application in the detection of biomolecules.

The development of hybrid nanoscintillators is hunted for the implementation of modern detection technologies, like in high energy physics, homeland security, radioactive gas sensing, and medical imaging, as well as of the established therapies in radiation oncology, such as in X-ray activated photodynamic therapy. Engineering of the physico-chemical properties of nanoparticles (NPs) enables the manufacture of hybrids in which the conjugation of inorganic/organic components leads to increased multifunctionality and performance. However, the optimization of the properties of nanoparticles in combination with the use of ionizing radiation is not trivial: a complete knowledge on the structure, composition, physico-chemical features, and scintillation property relationships in hybrid nanomaterials is pivotal for any applications exploiting X-rays. In this paper, the design of hybrid nanoscintillators based on ZnO grown onto porous SiO 2 substrates (ZnO/SiO 2 ) has been performed in the view to create nanosystems potentially suitable in X-ray activated photodynamic therapy. Indeed, cytotoxic porphyrin dyes with increasing concentrations have been anchored on ZnO/SiO 2 nanoparticles through amino-silane moieties. Chemical and structural analyses correlated with photoluminescence reveal that radiative energy transfer between ZnO and porphyrins is the principal mechanism prompting the excitation of photosensitizers. The use of soft X-ray excitation results in a further sensitization of the porphyrin emission, due to augmented energy deposition promoted by ZnO in the surroundings of the chemically bound porphyrin. This finding unveils the cruciality of the design of hybrid nanoparticles in ruling the efficacy of the interaction between ionizing radiation and inorganic/organic moieties, and thus of the final nanomaterial performances towards the foreseen application.

The detection of volatile organic compounds by gas sensors is of great interest for environmental quality monitoring and the early-stage and noninvasive diagnosis of diseases. Experiments found hexane, toluene, aniline, butanone, acetone, and propanol gases in the exhaled breath of patients suffering from COVID-19, lung cancer, and diabetes. However, no studies are available to systematically elucidate the selectivity of these gases on nanosheets of zinc oxide for chemiresistive and direct thermoelectric gas sensors. Therefore, this work performed the elucidation by studying the electronic, electrical, and thermal properties of the bilayered ZnO nanosheets with polar (0001) and non-polar (112̄0) surfaces under the adsorption of the gases. The interaction between the gases and the nanosheets belongs to two groups: electrostatic attraction and charge exchange. The second one occurs due to the peak resonance of the same type of orbitals between the substrates and the gases along the surface normal and the first one for the other cases. The characteristics of the Seebeck coefficient exhibited distinct selectivity of butanone and acetone.

Semiconducting nanoparticles called quantum dots (Qds) present unique optoelectronic properties based on their extremely small size, composition, and spherical shape, which make them suitable for use as diagnostic and theranostic agents in biological samples. The main scope of the fabrication of Qds is real-time diagnosis, therapy, drug delivery, and in vitro and in vivo tracking, presenting strong resistance to photobleaching. In this work, quantum dots such as ZnO, ZnSe, ZnS, and doped ZnS : Mn and ZnS : Cd were developed via a simple sol-gel synthesis in an aqueous solution. Morphological, structural, and optical characterizations were investigated. Moreover, an in vitro biological evaluation of Qds was performed. The results indicate that the photoluminescence is enhanced after doping ZnS Qds with Mn 2+ and Cd 2+ . Qds have been synthesized for use as fluorescent agents for real-time monitoring in bio-applications.

To maximize the biological activity of branched-chain amino acids (BCAAs), it is necessary to find a new excipient agent to increase the bioavailability of BCAAs in protein mixtures. The aim of the current study was to investigate the effects of soy lecithin (SLC), zinc oxide (ZnO), and methylsulfonylmethane (MSM) on the bioaccessibility and intestinal transport of BCAAs from animal and plant protein mixtures (PMs) via an in vitro digestion model with human intestinal epithelial (Caco-2) cells. The bioaccessibility of total BCAAs in PMs considerably increased by 107.51 ± 1.50% with the addition of SLC, and the combined effects of SLC, ZnO, and MSM on enhancing the bioaccessibility of total BCAAs was observed (107.14 ± 0.18%). Interestingly, SLC showed a major role in binding bile acid, showing 65.78 ± 1.66% of binding capacity. Intestinal transport of BCAAs was measured to be at 100.48, 110.86, and 130.29 μg mL -1 for leucine, isoleucine, and valine, respectively, in PMs with SLC + ZnO + MSM, and it eventually amplified the amount of the total transported BCAAs (341.63 ± 6.34 μg mL -1 ), which was about 8.72 times higher than that of PM only. The cellular integrity of digesta-treated Caco-2 cells tended to decrease according to the incubation time, but it was recovered in the treatment of PM + SLC + ZnO + MSM, and nearly reached the control levels with 92.82 ± 0.53%. Results from the current study suggest that the co-consumption of proteins equally consisting of plant and animal sources with SLC, ZnO, and MSM could improve the bioavailability of total BCAAs, resulting in the improvement of health benefits.

We report here a novel photocurrent polarity switching strategy for a photoelectrochemical immunoassay driven by the covalent reaction between fullerenol (COH) and chloranilic acid (CA). The sensitive detection of interleukin-6 is achieved by using CA-encapsulated liposome as the label and COH-coated ZnO as the photoactive material, with a detection limit of 1.0 fg mL -1 .

This work reports a photoelectrochemical (PEC) biosensing platform for the sensitive and specific screening of thrombin by using graphene oxide-coated copper-doped zinc oxide quantum dots (Cu 0.3 Zn 0.7 O-GO QDs) as the photoactive materials and glucose oxidase-encapsulated DNA nanoflowers (GOx-DFs) for signal amplification. Interestingly, the coated graphene oxide nanosheets on the surface of the Cu 0.3 Zn 0.7 O QDs could cause the charge to transfer rapidly and ameliorate the photocorrosion. The doped copper into the quantum dots could enhance the absorption of visible light by tuning the band gap of ZnO QDs, therefore increasing the photocurrent under visible irradiation. Upon addition of target thrombin, a sandwiched reaction was carried out between thrombin aptamer and GOx-DFs, accompanying the formation of nanocomposites with the magnetic microparticles (MMPs)/thrombin/GOx-DFs. Followed by magnetic separation, the carried GOx oxidized glucose to H 2 O 2 , thus resulting in the increasing photocurrent of the Cu 0.3 Zn 0.7 O-GO QD-modified electrode. Under optimum conditions, the developed PEC biosensing platform exhibited good analytical performance with a linear range of 50-10 000 fM thrombin and a limit of detection of 29 fM. Impressively, our strategy offers a new horizon in developing bridge-connected graphene-coated nanomaterials and novel signal amplification strategy for the development of PEC biosensors.

A highly selective and sensitive photoelectrochemical (PEC) detection method has been developed for the analysis of copper (Cu2+) ions using nanoflower-like ZnO@CdS heterojunctions, of which ZnO was first in situ grown onto the indium tin oxide electrodes by a hydrothermal method and then coated with CdS through the chemical bath deposition route. It was discovered that the ZnO@CdS heterojunction so formed could serve as a photosensitive catalyst with improved charge separation for visible-light-driven PEC responses. Enhanced visible-light harvesting of nanocomposites could also be expected with CdS as the visible-light sensitizer. Furthermore, the introduction of Cu2+ ions could cause a rational decrease in the photocurrents of nanocomposites through the specific interaction between CdS and Cu2+ ions. A ZnO@CdS heterojunction-based PEC sensor was thereby developed for the detection of Cu2+ ions in blood in the linear concentrations ranging from 0.50 to 80 nM, with a limit of detection of 0.18 nM. Such a heterojunction-based PEC detection platform constructed using two photocatalytic materials with matched band structures are promising for a wide range of applications for sensing Cu2+ ions in clinical diagnostics, food monitoring, and environmental analysis.

Dual network (DN) hydrogels with excellent mechanical strength and controllable component adjustment characteristics have a broad application range in the field of biomedicine. However, the tissue adhesion, skin affinity, self-healing, and antibacterial properties of DN hydrogels are inadequate for their application as skin patches. In this work, we prepared dopamine/zinc oxide (DOPA/ZnO) doped poly(N-hydroxyethyl acrylamide) (p(HEAA))/agar DN hydrogels and combined them to obtain a bilayer hydrogel (two-layer gel) with moisturizing properties. Upon incorporating 0.86 wt% of dopamine (DOPA), the resultant DOPA/p(HEAA))/agar DN hydrogel (DOPA@DNG) exhibited high tensile strain (up to 1600%), excellent self-repair ability, and tissue adhesion. ZnO/p(HEAA))/agar DN hydrogel (ZnO NG) obtained by incorporating 2 w/v ZnO nanoparticles (ZnO NPs) achieved high tensile strength (1.2 MPa), good antibacterial ability, and low charge transfer resistance. Moreover, ZnO NG, which has a tight structure, was employed as a protective layer for the two-layer gel, which can effectively slow down the excessive evaporation of water to protect the DOPA@DNG stability as a skin patch. Evidence showed that the two-layer hydrogel has water retention. Water retention still remains at over 50% after keeping the hydrogel in air for 3 days. These properties mean the two-layer gel based on the DOPA/ZnO doped DN hydrogels could be used as a transdermal patch for numerous applications in drug delivery, wearable devices, and electronic skin.

Leukocyte esterase (LE) is a useful marker that can be used in establishing a diagnosis of urinary tract infections (UTIs). The development of a UTI diagnostic method with quantitative determinations of biomarkers across all age groups is becoming more important. In this report, microfluidic resistance sensors based on silver ink (Ag ink) and silver ink mixed with ZnO nanoparticles (Ag-ZnO ink) were synthesized and coated on cellulose paper, namely LE-Ag-μPADs and LE-Ag-ZnO-μPADs, respectively, for the sensitive detection of LE. The microfluidic design increases the precision of data and further allows for quantitative determination and early detection of LE in human urine. The quantification of LE relies on the change in the resistance readout coating with Ag ink as well as Ag-ZnO ink in the detection zone. A mixture of 3-(N-tosyl-l-alaninyloxy)-5-phenylpyrrole (PE) and 1-diazo-2-naphthol-4-sulfonic acid (DAS) was deposited in the sample zone to selectively recognize LE, and the resulting nonconductive products, i.e., azo compounds, further reacted with the Ag ink and Ag-ZnO ink to increase resistance. The quantitative detectable LE concentrations between 2 to 32 (×5.2 U mL-1), i.e. ≈12 to 108 μg L-1, cover the commercial dipstick range of trace, +1 and +2. The minimum detectable concentration of LE in urine was 1 (×5.2 U mL-1). The lower concentrations of LE detectable by LE-Ag-μPADs (1-8 × 5.2 U mL-1) are below the value achieved with the ELISA LE kit. Urine samples from inpatients with indwelling urinary catheters were used, and the LE levels measured by the present device were highly correlated with those determined by a commercial urine analyser.

In our previous study, zinc oxide nanoparticles (ZnO NPs) presented satisfying therapeutic effects with cancer cell selectivity in osteosarcoma cells and, thus, have been considered as a potential nanomedicine for human osteosarcoma treatment. However, the poorly investigated internalization process, including their endocytic pathway into tumor cells and intracellular fate, limits the clinical application. Here, we further clarified these aspects. First, ZnO NPs were rapidly internalized by osteosarcoma cells and accumulated in mitochondria, before being entrapped into lysosomes. Second, dynasore (a dynamin inhibitor) was demonstrated to be the most effective in blocking ZnO NP uptake and rescuing ZnO NP-induced osteosarcoma cell autophagic death and apoptosis. Third, we confirmed the key role of dynamin 2 in ZnO NP endocytosis and subsequent autophagic cell death in vitro and in vivo. Furthermore, we proved that VPS34 transferred from cell cytoplasm to cell membrane to interact with dynamin under ZnO NP treatment. Altogether, combined with our previous study, the current research further revealed that ZnO NPs entered human osteosarcoma cells through the VPS34/dynamin 2-dependent endocytic pathway, directly targeting and damaging the mitochondria before being entrapped into the lysosomes, thereby initiating mitophagy-Zn 2+ -reactive oxygen species-mitophagy axis mediated cell apoptosis.

Zinc oxide nanoparticles (ZnO NPs) are known for their antibacterial, antioxidant, and anti-inflammatory activities. Moreover, ZnO NPs can stimulate cell migration, re-epithelialization, and angiogenesis. All these attributes are highly relevant to wound healing. Local administration of ZnO NPs to the wound can be achieved through electrospun nanofibers. We hypothesized that the use of poly(lactide-co-glycolic acid) (PLGA)/silk fibroin (SF) nanofiber-based delivery of ZnO would maintain the bioavailability of NPs on the wound area and synchronization with the unique structural features of electrospun nanofibers, could stimulate wound closure, re-epithelialization, collagen deposition, cellular migration, and angiogenesis. In this study, we fabricated PLGA/SF (PS) nanofibrous (NF) membranes with and without ZnO NPs and extensively characterized them for various physicochemical and biological attributes. Scanning electron microscopy (SEM) revealed smooth fibers and ZnO concentration-dependent increase in the fiber diameter. Transmission electron microscopy (TEM) also confirmed the encapsulation of ZnO NPs in the polymer matrix. The successful loading of ZnO was further confirmed by X-ray diffraction. Furthermore, mechanical testing revealed a ZnO concentration-dependent increase in the tensile strength. Moreover, biocompatibility was evaluated through in vitro cell culture. A mild anti-oxidant activity was also noted mainly due to the presence of silk fibroin. In vitro antibacterial tests revealed a ZnO concentration-dependent increase in antibacterial activity and PLGA/SF/3% ZnO (PSZ3) remained completely active against E. coli and S. aureus. More importantly, NF membranes were evaluated for their in vivo wound healing potential. The PSZ3 NF membrane not only facilitated the early wound closure but also remarkably enhanced the quality of wound healing confirmed through histopathological analysis. Re-epithelialization, granulation tissue formation, collagen deposition, and angiogenesis are some of the key parameters significantly boosted by ZnO loaded composite NF membranes. Based on extensive characterization and biological evaluation, the PSZ3 NF membrane has turned out to be a potential candidate for wound healing applications.

Persistent luminescence nanoparticles (PLNPs) emitting in the NIR window (700-1700 nm) have shown great promise in the field of fluorescence imaging due to their unique properties, including the absence of in situ excitation and low optical scattering in tissues. However, they are still facing some challenges, such as irregular shape, wide size distribution and poor persistent luminescence performance. Here, we report a facile mesoporous template method for synthesizing mSiO 2 @Zn 0.6 Ca 0.4 Ga 2 O 4 :Cr 3+ ,Yb 3+ (mSiO 2 @ZCGO) persistent luminescent nanoparticles, which show a regular morphology and a size of about 69 nm. In addition, these nanocrystals exhibit persistent luminescence in multi-NIR windows, the first infrared window (∼696 nm of Cr 3+ emission) and second infrared window (∼1000 nm of Yb 3+ emission). Under illumination of a 254 nm UV lamp for 10 min, the persistent time of Cr 3+ ions and Yb 3+ ions lasted more than 120 min and 10 min, respectively. In particular, the NIR persistent emission of mSiO 2 @ZCGO could be stimulated by soft X-ray, which is beneficial to long-term imaging in deep tissues. The optical penetration length of Yb 3+ ions persistent luminescence was evaluated to be 2.8 mm. These results demonstrate the great promise of mSiO 2 @ZCGO for deep-tissue bio-imaging.

Sensitive detection of copper ions (Cu 2+ ) in biological samples is extremely important since an abnormal level of Cu 2+ is linked with many diseases. Herein, we demonstrated a novel turn-on colorimetric sensor for selective detection of Cu 2+ both in buffered solution and serum samples based on porous bimetallic transition metal oxide nanocages (ZnO-Co 3 O 4 NCs) as peroxidase mimics. The ZnO-Co 3 O 4 NCs were prepared by using ZnCo-zeolitic-imidazolate-framework (ZnCo-ZIF) as precursors via direct calcination. With the high peroxidase-like activity, the obtained ZnO-Co 3 O 4 NCs can catalyze the oxidation of tetramethylbenzidine (TMB) in the presence of H 2 O 2 to form a blue colored product. The inhibition effect of cysteine (Cys) on the catalytic activity of ZnO-Co 3 O 4 NCs and its strong binding ability toward Cu 2+ enabled the ZnO-Co 3 O 4 NCs/Cys system to be utilized for sensitive detection of Cu 2+ , in which the catalytic activity of ZnO-Co 3 O 4 NCs/Cys can be recovered by the introduction of Cu 2+ with an obvious color change of the solution. The linear range for Cu 2+ determination was 2 to 100 nM with a detection limit of 1.08 nM. More importantly, this colorimetric sensor has been successfully applied to detect Cu 2+ in serum without pretreatment. Our findings are expected to expand the scope of application of nanozyme and shed light on early disease diagnosis.

This work for the first time evaluates the ability of homogeneous, stable, and pure zinc oxide nanoparticles (ZnONPs-GS) synthesized by "green chemistry" - an environmentally friendly, cheap, and easy method that allows efficient use of plant waste, such as banana peels, for the selective detection of four neurotransmitters present in body fluids and promotion of the SERS effect. Selective adsorption on ZnONPs-GS was compared with adsorption on the surface of (1) ZnONPs, which were obtained by electrochemical dissolution of zinc in a solution free of surfactants and (2) mechanically polished surface of bare Zn. The study showed that SERS spectroscopy using unique marker bands allows distinguishing whether the adsorbate is deposited on the surface of zinc or zinc oxide. Thus, the combination of the SERS technique with an optical probe can allow an in vivo determination of the condition of galvanized implants. The use of SERS has been extended to monitor the photocatalytic properties of surface-functionalized ZnO nanoparticles. It has been shown that despite the same structure, purity, and adsorption properties, ZnONPs-GS obtained using "green chemistry" are more bio-friendly for biological material than those obtained by the electrochemical method. This is because the surface of ZnONPs-GS is free of hydroxyl groups, which can easily form reactive oxygen species when the surface is exposed to visible radiation. Thus, surface-functionalized ZnONPS-GS can protect the biological material from the damage caused by the production and attack of an excess of ROS. Also, for an exemplary neurotransmitter, structural changes when it is not-covalently bound to Zn/ZnO were compared with the structural changes of this neurotransmitter deposited on the surface of various metals (Cu, α-Ti, and α-Fe) and metal oxides (leaf-like CuO, rutile-TiO2, and γ-Fe2O3). It has been shown that adsorption only slightly depends on the type of metallic surface and the development of this surface for roughness up to 1 micron. Metal substrates were characterized before and after the neurotransmitters' adsorption. UV-Vis, Raman, and ATR-FTIR confirmed the formation of ZnO nanoparticles. XRD showed a high crystalline structure of wurtzite. TEM and DLS showed that nanoparticles are spherical, well dispersed, and have a uniform size.

A facile, green synthesis of selenium doped zinc oxide nano-antibiotic (Se-ZnO-NAB) using the Curcuma longa extract is reported to combat the increased emergence of methicillin-resistant Staphylococcus aureus (MRSA). The developed Se-ZnO-NAB were characterized for their physicochemical parameters and extensively evaluated for their toxicological potential in an animal model. The prepared Se-ZnO-NABs were characterized via Fourier transformed infrared spectroscopy to get functional insight into their surface chemistry, scanning electron microscopy revealing the polyhedral morphology with a size range of 36 ± 16 nm, having -28.9 ± 6.42 mV zeta potential, and inductively coupled plasma optical emission spectrometry confirming the amount of Se and Zn to be 14.43 and 71.70 mg L-1 respectively. Moreover, the antibacterial activity against MRSA showed significantly low minimum inhibitory concentration at 6.2 μg mL-1 when compared against antibiotics. Also, total protein content and reactive oxygen species production in MRSA, under the stressed environment of Se-ZnO-NAB, significantly (p < 0.05) decreased compared to the negative control. Moreover, the results of acute oral toxicity in rats showed moderate variations in blood biochemistry and histopathology of vital organs. The teratogenicity and fetal evaluations also revealed some signs of toxicity along with changes in biochemical parameters. The overall outcomes suggest that Se-ZnO-NAB can be of significant importance for combating multi-drug resistance but must be used with extreme caution, particularly in pregnancy, as moderate toxicity was observed at a toxic dose of 2000 mg kg-1.

Highly efficient photoactive antimicrobial coatings were obtained using zinc oxide-reduced graphene oxide nanocomposites (ZnO-rGO). Their remarkable antibacterial activity and high stability demonstrated their potential use for photoactive biocide surfaces. The ZnO-rGO nanocomposites were prepared by the sol-gel technique to create photocatalytic surfaces by spin-coating. The coatings were deeply characterised and several tests were performed to assess the antibacterial mechanisms. rGO was homogeneously distributed as thin sheets decorated with ZnO nanoparticles. The surface roughness and the hydrophobicity increased with the incorporation of graphene. The ZnO-rGO coatings exhibited high activity against the Gram-positive bacterium Staphylococcus aureus. The 1 wt% rGO coated surfaces showed the highest antibacterial effect in only a few minutes of illumination with up to 5-log reduction in colony forming units, which remained essentially free of bacterial colonization and biofilm formation. We demonstrated that these coatings impaired the bacterial cells due to cell membrane damage and intracellular oxidative stress produced by the photogenerated reactive-oxygen species (ROS). The enhancement of the ZnO photocatalytic performance upon rGO incorporation is due to the increased detected generation of hydroxyl radicals, attributed to the reduction of electron-hole pair recombination. This intimate contact between both components also conveyed stability against zinc leaching and improved the coating adhesion.

Nanostructured metal oxides, such as zinc oxide (ZnO), are considered as excellent materials for the fabrication of highly sensitive and selective electrochemical sensors and biosensors due to their good properties, including a high specific surface area, high catalytic efficiency, strong adsorption ability, high isoelectric point (IEP, 9.5), wide band gap (3.2 eV), biocompatibility and high electron communication features. Thus, ZnO nanostructures are widely used to fabricate efficient electrochemical sensors and biosensors for the detection of various analytes. In this review, we have discussed the synthesis of ZnO nanostructures and the advances in various ZnO nanostructure-based electrochemical sensors and biosensors for medical diagnosis, pharmaceutical analysis, food safety, and environmental pollution monitoring.

Nanostructures of Cu-doped ZnO (Cu:ZnO) were prepared with the chemical precipitation technique with an aim to enhance the photocatalytic and antibacterial properties of ZnO. Phase constitution, the presence of functional groups, optical properties, elemental composition, surface morphology and microstructure were evaluated using an X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis spectrophotometer, energy dispersive X-ray spectroscopy (EDS), field emission scanning electron microscope (FESEM) and high resolution transmission electron microscope (HR-TEM), respectively. Emission spectra were obtained with a photoluminescence (PL) spectroscope whereas interlayer d-spacing was estimated through HR-TEM. ZnO consisted of a hexagonal wurtzite structure. The crystallinity of the sample was observed to increase with increasing doping concentration. The addition of Cu to ZnO served to transform nanoclusters into nanorods as revealed during SEM analysis. Catalytic activity enhanced due to the formation of nanorods, and UV-Vis absorption spectra showed that methylene blue (MB) degraded more efficiently with ZnO nanoclusters compared to the NaBH4 reagent. In addition, the doped NPs showed enhanced bacterial efficiency for G +ve. Finally, a molecular docking study was undertaken to highlight the importance of the binding interactions of the Cu-doped ZnO nanorods with β-lactamase and beta-ketoacyl-acyl carrier protein synthase III (FabH) as possible enzyme targets. This research indicates that Cu-doped Zn nanorods are a highly efficient photocatalyst and can be aptly employed for wastewater treatment and antibacterial applications.

The importance of zinc as a trace metal in the human body has long been overlooked. We now gradually discover that the impact of zinc on the health of our body might be as far-reaching as that of iron. Concurrently, nanomaterials containing zinc, in particular zinc oxide nanoparticles (ZnO NPs), are becoming increasingly attractive as innovative agents for medical applications. Zinc oxide is characterized by a good biocompatibility which allows the exploitation of its antibacterial, antifungal, antiviral, and anti-cancer qualities in a therapeutic setting. This perspective outlines the current state of knowledge concerning the interaction of zinc oxide nanoparticles with eukaryotic cells and the human body. Furthermore, it sheds light on the importance of zinc under physiological conditions. This helps to place the in vivo behavior of zinc oxide nanoparticles in the proper context. We evaluate the potential of zinc oxide nanoparticles as innovative anti-tumor agents by summarizing important results of current studies in this field and discuss the proposed mechanisms that give zinc oxide nanoparticles a selective toxicity for tumor cells.

A urinary tract infection (UTI) is a recurrent infection that requires timely diagnosis and appropriate treatment. Conventional urinalysis methods are laborious and time-consuming, and lack sensitivity and specificity. In this context, photoluminescence (PL)-based biosensors have gained more attention due to their fast response time, and enhanced sensitivity and specificity. In relation to this, a PL-based biosensor was developed using ZnO nanoparticles obtained via a microwave-assisted process functionalized with cysteamine (ZnO-Cys) to detect the quorum sensing signalling molecules of Gram-negative bacteria, N-acyl-homoserine lactones (AHLs). These AHLs are involved in bacterial communication and are responsible for activating virulence and pathogenicity. Biosensing measurements based on PL intensity variations corresponding to the O 2 acceptor defect level of ZnO with reference to ZnO-Cys were considered. A maximum sensitivity of 97% was achieved in the detection of AHL. The linear detection range of the developed biosensor was 10-120 nM in artificial urine media (AUM). The effect of pH on the sensitivity of the biosensor in AUM was also investigated and reported. The developed sensor was validated using the AHLs produced by Pseudomonas aeruginosa (MCC3101) in real-time analysis, which further confirmed the overall specificity and sensitivity.

Zinc oxide (ZnO) materials hold great promise in diverse applications due to their attractive physicochemical features. Recent years, especially the last decade, have witnessed considerable progress toward rational design and bioapplications of multiscale ZnO materials through microfluidic techniques. Design of a microfluidic device that allows for precise control over reaction conditions could not only yield ZnO particles with a fast production rate and high quality, but also permit downstream applications with desirable and superior performance. This review summarizes microfluidic approaches for the synthesis and applications of ZnO micro-/nanomaterials. In particular, we discuss the recent achievement of using microfluidic reactors in the controllable synthesis of ZnO structures (wire, rod, sphere, flower, sheet, flake, spindle, and ellipsoid), and highlight the unprecedented opportunities for applying them in biosensing, biological separation, and molecular catalysis applications through microfluidic chips. Finally, major challenges and potential opportunities are explored to guide future studies in this area.

A g-C 3 N 4 /ZnO/cellulose ternary composite (labeled as CNZCel) with an ordered structure and excellent antibacterial properties has been successfully synthesized via a facile method. Its morphology, microstructure and components have been analyzed by using XRD, SEM, TEM and EDS, and the results corroborate the co-existence of three components in the ternary composite. It is revealed that ZnO particles are connected to the layered g-C 3 N 4 and simultaneously attached to the cellulose substrate. This microstructural feature is also borne out by the relativistic density functional study of a finite g-C 3 N 4 -ZnO-cellulose cluster. Both experimental and theoretical results unravel that the interfacial bonding interactions in the ternary composite improve electron transfer among components and enable high-efficiency spatial separation of photogenerated electrons and holes. Consequently, good antibacterial performance of the composite has been found in tests. This study provides the prospect of preparing low-cost and environment-friendly food packaging materials, which are also endowed with excellent antibacterial activity.

In this study, a new type of β-1,3-d-glucan porous microcapsule (GPM)-enveloped and folate conjugated chitosan-functional liposome (FCL), FCL@GPM, was developed for the potential oral co-delivery of chemotherapeutic drugs and quantum dots (QDs) with facilitated drug absorption and antitumor efficacy. In this dual-particulate system, multiple FCLs serve as the cores for effective loading, folate-mediated tumor-targeting, facilitated intracellular accumulation, and pH-responsive controlled release of chemotherapeutic agents, while a GPM acts as the shell for affording macrophage-mediated tumor selectivity. Gefitinib (GEF) was selected as a chemotherapeutic agent, while acid degradable ZnO QDs were selected due to their dual role as an anticancer agent for synergistic chemotherapy and as a fluorescent probe for potential cancer cellular imaging. The GEF and ZnO QD co-loaded FCL@GPMs (GEF/ZnO-FCL@GPMs) exhibited a prolonged release manner with limited release before uptake by intestinal cells. Furthermore, Peyer's patch uptake, macrophage uptake, cytotoxicity, and biodistribution of FCL@GPMs were tested. In addition, GEF and ZnO QD co-loaded FCLs (GEF/ZnO-FCLs) not only have a tumor acidity responsive release property, but also induce a superior cytotoxicity on cancer cells as compared to GEF. Moreover, a 1.75-fold increase in the bioavailability of GEF delivered from GEF/ZnO-FCL@GPMs as compared to its trademarked drug (Iressa®). As a result, GEF/ZnO-FCL@GPMs exerted a superior antitumor efficacy (1.47-fold) as compared to the trademarked drug in mice. Considered together, the developed FCL@GPMs, combining the unique physicochemical and biological benefits of FCLs and GPMs, possess great potential as an efficient delivery system for the co-delivery of chemotherapeutic agents and quantum dots.

Compared with normal cells, cancer or tumor cells have a specific microenvironment and apparently possess a relatively large amount of ROS/RNS, and their overexpression is one of the important reasons for tumor development and deterioration. Therefore, monitoring the changes of intracellular ROS/RNS can improve the awareness of the clinical manifestations of the disease, which will be beneficial for the early diagnosis of cancer and improving treatment efficiency. Herein, in this study we have exploited and constructed a novel strategy based on the SiC@C nanowire electrode for intracellular electrochemical analysis to monitor ROS levels in cancer or tumor cells. Firstly, the SiC@C nanowire electrode was utilized to detect the intracellular ROS radical changes involved in the relevant biological processes of cancer cells where fluorescent zinc nanoclusters were biosynthesized in situ in target cancer cells by using the intracellular microenvironment and specificity of these cancer cells. By combining a confocal fluorescence microscopy study simultaneously, our observations illustrate that accompanied by the apparent change of the intracellular ROS, these in situ biosynthesized fluorescent nanoclusters gradually accumulate inside the cytosolic area with the increase of the reaction time. Moreover, it is evident that the size of the SiC@C nanoelectrodes can match the single cell dimensions, and its unique high spatial resolution provides the possibility of relevant intracellular molecular detection. These nanoelectrochemical biosensors can be adopted to quantitatively determine the change of the ROS content in target single cells in the relevant biological microenvironment or during the in situ biosynthesis process, and are also beneficial for understanding the related mechanism of some specific biological processes including the in situ synthesis at the single cell level.

Agri-biomass derived lignin is one of the most abundant natural nontoxic organic polymers. However, a major portion of lignin is underutilized, which is being left in the fields or thrown into rivers, causing waste accumulation. Utilization of the low-cost biomass-derived lignin serves a dual purpose by reducing agri-waste and by converting it into value-added materials. Here we describe the valorization of agri-biomass based lignin via its direct utilization in the green and one-step synthesis of zinc oxide nanocomposites. Lignin offered an easy and sustainable synthesis of nanocomposites in a water-ethanol mixture without the need to use any toxic material. The lignin derived nanomaterials showed excellent potential as antioxidant, UV-blocking and antimicrobial agents due to the synergistic effect of lignin and zinc oxide. Further, these nanocomposites were incorporated as an additive into a commonly used body cream to impart UV-blocking and antimicrobial properties. This one-step, cost-effective and green synthesis technique of lignin derived zinc oxide nanocomposites not only contributes to agro-waste reduction, but at the same time helps in the production of value-added materials.

Current sutures have disadvantages such as poor antibacterial activities, low healing effects, and a lack of self-degradation ability. To solve these problems, here a biocompatible and dual light (yellow and NIR light) responsive porous ZnO (PZ) was synthesized to modify silk thread to improve the healing rate, antibacterial activities and controlled self-degradation speed simultaneously. The prepared silk thread was characterized by using scanning electron microscopy (SEM) and X-ray diffractometry (XRD). Besides, the antibacterial activity, degradation, dual light responsive capability and cytocompatibility of the sample were evaluated. The obtained data strongly encourage the application of this silk thread for wound treatment. Furthermore, in vivo evaluation in mice revealed that the silk thread reduced surgical-site infection and enhanced wound healing. Therefore, this silk thread shows potential for application in wound treatment clinically.

In this communication, a synergistic strategy of bio-recognition/spatial-confinement has been proposed for the effective capture of cancer cells and sensitive photoelectrochemical detection with the lowest limit of detection of 2 cells per mL. The synergistic strategy opens up a new avenue for rational combination of bio-molecule recognition units and nanostructures for bio-detection.

Scar formation in severe burn injury is a major health concern. Herein, we developed a hybrid collagen scaffold with an incorporated ZnO-curcumin nanocomposite, which facilitates scarless wound healing. Biocompatibility and hemocompatibility studies unveiled that the hybrid scaffold is apt for in vivo wound healing studies. Histological and immunohistochemical analyses demonstrate that the hybrid scaffold accelerated scarless burn wound healing in albino rats owing to the ZnO-curcumin nanocomposite induced up-regulation of angiogenesis and TGF-β3 expression. The semi-quantitatively measured scar elevation index of the hybrid scaffold-treated animals is on a par with that of the unwounded or normal skin. The studies suggest that the prepared hybrid biomaterial could be a potential candidate for scarless healing in severe burn injuries.

Graphene-based composite materials are versatile but not easily procurable. Cyanobacterial cells, an outgrowth of eutrophic freshwater lake, were simultaneously employed as a template for the growth of ZnO nanoparticles and as a biomass carbon source for graphene sheets, resulting in chlorophyll-containing graphene-wrapped ZnO nanospheres.

Cardiac pacemakers are the main implant devices for cardiovascular diseases, and their utilization and consequently the number of cases of inflammation caused by these devices are increasing year by year. Although few antibacterial treatments have been proposed for pacemakers, the rate of cardiac pacemaker-related inflammation still exhibits an abnormal increase. By analyzing the statistical reports of the inflammation at different time stages caused by pacemakers, herein, we proposed a new hypothesis to explain this unusual phenomenon. That is, in addition to bacterial infection, the long-term stimulation caused by the frequent shaking of the pacemakers in the subcutaneous tissue "pocket" may be an important hidden factor of the inflammation. This assumption was then preliminarily confirmed through the animal-shaking model. Accordingly, we developed a new memory latex foam with ZnO surface modification (LFZ), which was incorporated with a slow springback, soft cushion and broad spectrum antibacterial properties. The subsequent animal experiments demonstrated that the incidence of both bacteria- and shaking-induced tissue inflammations could be fundamentally reduced through this multifunctional LFZ-based strategy.

Implant infections frequently occur in various kinds of surgery. Apart from antibiotics, the surface modification of implant material is a promising avenue to resolve this global problem. An ideal implant interface is expected to possess good biocompatibility, as well as broad-spectrum and long-term bacterial inhibition capabilities. Here, a delicate cicada and catkin inspired dual biomimetic structure was proposed, for the first time, to improve the antibacterial properties of implant material. By using poly(ether-ether-ketone) (PEEK) as a model implant, the relative in vitro and in vivo evaluations demonstrated that this dual biomimetic structure could simultaneously provide less bacterial adhesion, wider antimicrobial range and longer antibacterial durability. Meanwhile, the modified implant also retained ideal biocompatibility. Most importantly, the relative dual biomimetic structure engineering process could be accomplished through a simple, economic and fast hydrothermal chemical reaction, which might have an impact on the development of future biomedical materials.

Herein, the CuO/ZnO@Fe3O4-carbon nanotubes (CNTs)-nanocomposite (NC), as a sorbent for magnetic dispersive micro-solid phase extraction, was developed for the determination of chlorogenic acid (CGA) in the medical extract of plants, food, and water samples in combination with high-performance liquid chromatography. The CuO/ZnO@Fe3O4-CNTs-NC was characterized by FESEM, EDS, XRD, TEM, BET, FT-IR, and VSM. Significant parameters (pH, temperature, eluent volume, vortex time, sonication time, CuO/ZnO@Fe3O4-CNTs-NC mass, and desorption time) that affected the extraction efficiency of CGA were optimized using Plackett-Burman as the screening design and the central composite design as the optimization strategy. Under the optimized conditions, the analytical parameters were obtained. The optimized method showed good linearity and a linear regression coefficient >0.9893. The enrichment factors ranged from 102.43 to 123.76 with the preconcentration factor of 60.0. The limits of detection (LOD) and the limits of quantification (LOQ) were 0.034-0.061 ng mL-1 and 0.114-0.202 ng mL-1, respectively. The method also reflected acceptable accuracy (from 94.07% to 109.7%) and the broad potential applications of CuO/ZnO@Fe3O4-CNTs-NC for the detection of CGA content in the medical extract of plants, food, and water samples.

Herein, mesoporous silica-zinc oxide (MS-Zn) micro-rosettes with controllable petal thickness were synthesized by a facile one-pot hydrothermal method. MS-Zn loaded with doxorubicin and polyinosinic-polycytidylic acid sodium salt not only significantly inhibits tumor growth but also effectively rejects tumor metastasis in vivo.