A chemical free, nanotechnology-based method for airborne bacterial inactivation using engineered water nanostructures

Assessment of immunopathological responses of a novel non-chemical biocide in C57BL/6 for safe disinfection usage

BACKGROUND

Water electrospray technology has been developed and extensively studied for its physical properties and potential application as a non-chemical biocide against airborne pathogens. However, there are still concerns regarding the safety and potential toxicity of inhaling water electrospray (WE) particles. To address these potential hazards and offer insights into the impact of WE on humans, we analyzed the immunopathological response to WE by employing an intranasal challenge C57BL/6 mouse model. This analysis aimed to compare the effects of WE with those of sodium hypochlorite (SH), a well-known biocidal agent.

RESULTS

The study findings suggest that the WE did not trigger any pathological immune reactions in the intranasal-challenged C57BL/6 mouse model. Mice challenged with WE did not experience body weight loss, and there was no increase in inflammatory cytokine production compared to SH-treated mice. Histopathological analysis revealed that WE did not cause any damage to the lung tissue. In contrast, mice treated with SH exhibited significant lung tissue damage, characterized by the infiltration of neutrophils and eosinophils. Transcriptomic analysis of lung tissue further confirmed the absence of a pathological immune response in mice treated with WE compared to those treated with SH. Upon intranasal challenge with WE, the C57BL/6 mouse model did not show any evidence of immunopathological damage.

CONCLUSIONS

The results of this study suggest that WE is a safe technology for disinfecting airborne pathogens. It demonstrated little to no effect on immune system activation and pathological outcomes in the intranasal challenge C57BL/6 mouse model. These findings not only support the potential use of WE as an effective and safe method for air disinfection but also highlight the value of the intranasal challenge of the C57BL/6 mouse model in providing significant immunopathological insights for assessing the inhalation of novel materials for potential use.

Non-touch treatment to solve the persistent contamination of culture plates with Aspergillus niger in a clinical microbiology laboratory of Spain

A pseudo-outbreak of Aspergillus caused by false positive cultures can have a high sanitary impact. We determined the effectiveness (fungal load elimination) of a non-touch disinfection system, vs conventional disinfection methods, to solve steady contamination of culture plates with Aspergillus niger at a clinical microbiology laboratory. Routine cleaning-disinfection (RCD), intensive cleaning-disinfection (ICD), and terminal airborne disinfection (TAD) were employed in stages. Air sampling was carried out before and after each procedure. The effectiveness of TAD on contact surfaces was tested by surface sampling. After RCD, ICD, and TAD, there was a mean decrease of 5.4 (95% CI = 1.8-9.0), 19.2 (95% CI = 12.4-26.0), and 4.4 (95% CI = 2.5-6.3) CFU per tested area, and 46.2%, 21.7%, and 95.5% of contaminated areas became sterile, respectively. There was a mean decrease of 30.6 CFU per tested surface (p < 0.0007) and 50% of tested surfaces became sterile. Global effectiveness of RCD, ICD, and TAD was 68.8% (95% CI = 68.5-69.1), 82.2% (95% CI = 82.1-82.3), and 99.0% (95% CI = 98.8-99.2), respectively. The effectiveness was higher with TAD (4.1 CFU/cm2 less than with ICD; p = 0.0290). No further contamination has occurred since then. When construction and renovation activities are discarded and RCD and ICD practices are insufficient, non-touch disinfection remove residual dust contamination and avoid recurrence.

Maintaining Antibacterial Activity against Biofouling Using a Quaternary Ammonium Membrane Coupling with Electrorepulsion

Antibacterial modification is a chemical-free method to mitigate biofouling, but surface accumulation of bacteria shields antibacterial groups and presents a significant challenge in persistently preventing membrane biofouling. Herein, a great synergistic effect of electrorepulsion and quaternary ammonium (QA) inactivation on maintaining antibacterial activity against biofouling has been investigated using an electrically conductive QA membrane (eQAM), which was fabricated by polymerization of pyrrole with QA compounds. The electrokinetic force between negatively charged Escherichia coli and cathodic eQAM prevented E. coli cells from reaching the membrane surface. More importantly, cathodic eQAM accelerated the detachment of cells from the eQAM surface, particularly for dead cells whose adhesion capacity was impaired by inactivation. The number of dead cells on the eQAM surface was declined by 81.2% while the number of live cells only decreased by 49.9%. Characterization of bacteria accumulation onto the membrane surface using an electrochemical quartz crystal microbalance revealed that the electrorepulsion accounted for the cell detachment rather than inactivation. In addition, QA inactivation mainly contributed to minimizing the cell adhesion capacity. Consequently, the membrane fouling was significantly declined, and the final normalized water flux was promoted higher than 20% with the synergistic effect of electrorepulsion and QA inactivation. This work provides a unique long-lasting strategy to mitigate membrane biofouling.

Multiplexed electrospraying of water in cone-jet mode using a UV-embossed pyramidal micronozzle film

The electrospraying of water in the cone-jet mode is difficult in practical applications owing to its low throughput and the electrical discharge caused by the high surface tension of water. A film with multiple dielectric micronozzles is essential for multiplexed electrospraying of water in cone-jet mode without electrical discharge. Thus, a pyramidal micronozzle film with five nozzles was fabricated using the UV-embossing process. The pyramidal micronozzle film consisted of pyramidal micronozzles, a micropillar array, and an in-plane extractor, which were proposed to minimize wetting and concentrate the electric field to the water meniscus at the tip of the pyramidal micronozzle. The electrospraying of water using a single pyramidal micronozzle was visualized by a high-speed camera at a flow rate of 0.15-0.50 ml/h with voltages of 0.0-2.3 kV, -1.6 kV, and -4.0 kV at the water, guide ring, and collector, respectively. Three distinct modes, the dripping, spindle, and cone-jet modes, were observed and distinguished according to the motion of the water meniscus at the nozzle tip. The steady Taylor cone and jet were observed in a voltage range of 1.3-2.0 kV in water, particularly in cone-jet mode. Multiplexed electrospraying of water in cone-jet mode at a flow rate of 1.5 ml/h was performed using a pyramidal micronozzle film, demonstrating the potential for a high-throughput electrospraying system.

Using engineered water nanostructures (EWNS) for wound disinfection: Case study of Acinetobacter baumannii inactivation on skin and the inhibition of biofilm formation

Engineered water nanostructures (EWNS) were utilized to deliver a cocktail of nature derived antimicrobials, to assess their efficacy as a solution to the problem of wound infections. The wound related microorganism Acinetobacter baumannii was inoculated on stainless steel and porcine skin and treated with EWNS. EWNS were able to reduce A. baumannii on stainless steel by 4.79 logs in 15 min, and 2 logs in 30 min on porcine skin. The EWNS were able to reduce the strength of A. baumannii biofilm on stainless steel by 87.31% as measured with the XTT assay (P < .001) and 86.27% in cellular counts (P < .001), after two EWNS interventions of 30 min each. Total antimicrobial dose delivered to the surface was 1.42 ng. SEM of biofilms after EWNS treatment showed reduced biomass. These results indicate that the EWNS technology has potential for application in field of wound disinfection and healing.

Enhancing Agrichemical Delivery and Plant Development with Biopolymer-Based Stimuli Responsive Core-Shell Nanostructures

The inefficient delivery of agrichemicals in agrifood systems is among the leading cause of serious negative planetary and public health impacts. Such inefficiency is mainly attributed to the inability to deliver the agrichemicals at the right place (target), right time, and right dose. In this study, scalable, biodegradable, sustainable, biopolymer-based multistimuli responsive core-shell nanostructures were developed for smart agrichemical delivery. Three types of responsive core/shell nanostructures incorporated with model agrichemicals (i.e., CuSO₄ and NPK fertilizer) were synthesized by coaxial electrospray, and the resulting nanostructures showed spherical morphology with an average diameter about 160 nm. Tunable agrichemical release kinetics were achieved by controlling the surface hydrophobicity of nanostructures. The pH and enzyme responsiveness was also demonstrated by the model analyte release kinetics (up to 7 days) in aqueous solution. Finally, the efficacy of the stimuli responsive nanostructures was evaluated in soil-based greenhouse studies using soybean and wheat in terms of photosynthesis efficacy and linear electron flow (LEF), two important metrics for seedling development and health. Findings confirmed plant specificity; for soybean, the nanostructures resulted in 34.3% higher value of relative chlorophyll content and 41.2% higher value of PS1 centers in photosystem I than the ionic control with equivalent agrichemical concentration. For wheat, the nanostructures resulted in 37.6% higher value of LEF than the ionic agrichemicals applied at 4 times higher concentration, indicating that the responsive core-shell nanostructure is an effective platform to achieve precision agrichemical delivery while minimizing inputs. Moreover, the Zn and Na content in the leaves of 4-week-old soybean seedlings were significantly increased with nanostructure amendment, indicating that the developed nanostructures can potentially be used to modulate the accumulation of other important micronutrients through a potential biofortification strategy.

Nanoprotection from SARS-COV-2: would nanotechnology help in Personal Protection Equipment (PPE) to control the transmission of COVID-19?

The coronavirus disease 2019 (COVID-19) has caused a worldwide outbreak. The severe acute respiratory syndrome coronavirus 2 virus can be transmitted human-to-human through droplets and close contact where personal protective equipment (PPE) is imperative to protect the individuals. The advancement of nanotechnology with significant nanosized properties can confer a higher form of protection. Incorporation of nanotechnology into facemasks can exhibit antiviral properties. Nanocoating on surfaces can achieve self-disinfecting purposes and be applied in highly populated places. Moreover, nano-based hand sanitizers can confer better sterilizing efficacies with low skin irritation as compared to alcohol-based hand sanitizers. The present review discusses the incorporation of nanotechnology into nano-based materials and coatings in facemasks, self-surface disinfectants and hand sanitizers, in the hope to contribute to the current understanding of PPE to combat COVID-19.

A Systematic Literature Review of Indoor Air Disinfection Techniques for Airborne Bacterial Respiratory Pathogens

Interrupting the transmission of airborne (<≈5 µm) respiratory pathogens indoors is not a new challenge, but it has attracted unprecedented interest due to the COVID-19 pandemic during 2020–2021. However, bacterial respiratory pathogens with known or potential airborne transmission account for an appreciable proportion of the communicable disease burden globally. We aimed to systematically review quantitative, laboratory-based studies of air disinfection techniques for airborne respiratory bacteria. Three databases (PubMed, Web of Science, Scopus) were searched, following PRISMA guidelines. A total of 9596 articles were identified, of which 517 were assessed in detail and of which 26 met the inclusion and quality assessment criteria. Seven air disinfection techniques, including UV-C light, filtration, and face masks, among others, were applied to 13 different bacterial pathogens. More than 80% of studies suggested that air disinfection techniques were more effective at inactivating or killing bacteria than the comparator or baseline condition. However, it was not possible to compare these techniques because of methodological heterogeneity and the relatively small number of the studies. Laboratory studies are useful for demonstrating proof-of-concept and performance under controlled conditions. However, the generalisability of their findings to person-to-person transmission in real-world settings is unclear for most of the pathogens and techniques we assessed.

A review of methods to reduce the probability of the airborne spread of COVID-19 in ventilation systems and enclosed spaces

COVID-19 forced the human population to rethink its way of living. The threat posed by the potential spread of the virus via an airborne transmission mode through ventilation systems in buildings and enclosed spaces has been recognized as a major concern. To mitigate this threat, researchers have explored different technologies and methods that can remove or decrease the concentration of the virus in ventilation systems and enclosed spaces. Although many technologies and methods have already been researched, some are currently available on the market, but their effectiveness and safety concerns have not been fully investigated. To acquire a broader view and collective perspective of the current research and development status, this paper discusses a comprehensive review of various workable technologies and methods to combat airborne viruses, e.g., COVID-19, in ventilation systems and enclosed spaces. These technologies and methods include an increase in ventilation, high-efficiency air filtration, ionization of the air, environmental condition control, ultraviolet germicidal irradiation, non-thermal plasma and reactive oxygen species, filter coatings, chemical disinfectants, and heat inactivation. Research gaps have been identified and discussed, and recommendations for applying such technologies and methods have also been provided in this article.

Mechanisms underlying inactivation of SARS-CoV-2 by nano-sized electrostatic atomized water particles

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a serious global issue. To prevent viral transmission, it is important to disinfect contaminated environmental surfaces and aerosols. We previously demonstrated that nano-sized electrostatic atomized water particles (NEAWPs) inactivate SARS-CoV-2. Herein, we focused on the underlying mechanisms. Morphological observation by transmission electron microscopy revealed that compared with NEAWPs-untreated virus, the shapes of particles corresponding to the size of SARS-CoV-2 particles were distorted significantly when exposed to NEAWPs. The amounts of viral RNA and protein in NEAWPs-treated SARS-CoV-2 showed a significantly greater decline than those in viruses unexposed to NEAWPs. Furthermore, much less NEAWPs-treated SARS-CoV-2 than NEAWPs-untreated virus bound to host cells. These results strongly suggest that NEAWPs damage the viral envelope, as well as viral protein and RNA, thereby impairing the ability of the virus to bind to host cells. Reactive oxygen species in NEAWPs may be involved in the inactivating effects on SARS-CoV-2.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11051-022-05485-5.

Research Note: Evaluation of the efficacy of engineered water nanostructures in inactivating airborne bacteria in poultry houses

Methods to control microbial contamination in confined livestock facilities are important to the health of both animals and workers. In addition, bacterial contamination is also a food safety issue. The most common disinfection technique employed in livestock facilities is the application of oxidizing agents (e.g., potassium peroxymonosulphate, chlorine, hydrogen peroxide, ozone). However, these techniques are associated with a number of limitations (e.g., toxicity, high cost, corrosiveness). Recently, engineered water nanostructures (EWNS) generated using an electrospray system was found effective in inactivating foodborne bacteria. Thus, this study investigated the efficacy of EWNS generated using a laboratory-scale electrospray system in inactivating bacteria found in poultry facilities. The effects of various operating conditions (distance between the injector and grounded electrode of the electrospray system, applied voltage, liquid pH and conductivity, liquid flow rate, and treatment time) on the efficacy were also assessed. In these various experiments, airborne bacterial samples were collected from a pullet room using tryptic soy agar plates and then exposed to EWNS under varying conditions. After treatment, the plates were incubated at 37°C prior to colony counting. Reductions in bacterial concentrations up to 1.26 logs were obtained. The results indicate that the EWNS generated by the electrospray system can be a potential chemical-free alternative to conventional disinfection methods. Future tests will focus on scaling up the system for larger scale trials.

Transport of Gaseous Hydrogen Peroxide and Ozone into Bulk Water vs. Electrosprayed Aerosol

Production and transport of reactive species through plasma–liquid interactions play a significant role in multiple applications in biomedicine, environment, and agriculture. Experimental investigations of the transport mechanisms of typical air plasma species: hydrogen peroxide (H2O2) and ozone (O3) into water are presented. Solvation of gaseous H2O2 and O3 from an airflow into water bulk vs. electrosprayed microdroplets was measured, while changing the water flow rate and applied voltage, during different treatment times and gas flow rates. The solvation rate of H2O2 and O3 increased with the treatment time and the gas–liquid interface area. The total surface area of the electrosprayed microdroplets was larger than that of the bulk, but their lifetime was much shorter. We estimated that only microdroplets with diameters below ~40 µm could achieve the saturation by O3 during their lifetime, while the saturation by H2O2 was unreachable due to its depletion from air. In addition to the short-lived flying microdroplets, the longer-lived bottom microdroplets substantially contributed to H2O2 and O3 solvation in water electrospray. This study contributes to a better understanding of the gaseous H2O2 and O3 transport into water and will lead to design optimization of the water spray and plasma-liquid interaction systems.

Advanced Oxidation Process as a Postharvest Decontamination Technology To Improve Microbial Safety of Fresh Produce

Fresh produce is frequently associated with outbreaks of foodborne diseases; thus, there is a need to develop effective intervention technologies and antimicrobial treatments to improve the microbial safety of fresh produce. Washing with chemical sanitizers, commonly used by the industry, is limited in its effectiveness and is viewed as a possible cross-contamination opportunity. This review discuses the advanced oxidation process (AOP), which involves generating highly reactive hydroxyl radicals to inactivate human pathogens. Ionizing irradiation, ultraviolet (UV) light, and cold plasma can be regarded as AOP; however, AOPs employing combinations of UV, H₂O₂, cold plasma, and ozone may be more promising because higher amounts of hydroxyl radicals are produced in comparison to the individual treatments and the combinative AOPs may be more consumer friendly than ionizing irradiation. When applied as a gaseous/aerosolized treatment, AOPs may have advantages over immersion treatments, considering the reactivity of hydroxyl radicals and presence of organic materials in wash water. Gaseous/aerosolized AOPs achieve up to 5 log reductions of pathogenic bacteria on fresh produce compared to reductions of 1-2 logs with aqueous sanitizers. Further research needs to be conducted on specific AOPs before being considered for commercialization, such as reduced formation of undesirable chemical byproducts, impact on quality, and scaled up studies.

Inactivation of common hospital acquired pathogens on surfaces and in air utilizing engineered water nanostructures (EWNS) based nano-sanitizers

Infectious diseases represent a major public health challenge worldwide. There are various modes for the transmission of these diseases, with surface and airborne transmission being two of the most important ones. The inefficiencies of current intervention methods have resulted in the emergence of nosocomial infections. Here, we report the use of a nanotechnology based antimicrobial platform using Engineered Water Nanostructures (EWNS) generated using a combined electrospray and ionization of an aqueous suspension of various active ingredients (AIs). These EWNS based nano-sanitizers were tested in terms of their ability to efficiently deliver AI and inactivate Acinetobacter baumannii and influenza H1N1/PR/8 on both surfaces and air. Results indicate a significant reduction in the concertation of the pathogens, while the delivered to pathogen AI doses required for inactivation were miniscule (nanogram level), indicating the viability of such nano-carrier platform as an intervention technology against infectious microorganisms.

Nanobubble Technologies Offer Opportunities To Improve Water Treatment

Since first hypothesizing the existence of nanobubbles (NBs) in 1994, the empirical study of NB properties and commercialization of NB generators have rapidly evolved. NBs are stable spherical packages of gas within liquid and are operationally defined as having diameters less than 1000 nm, though they are typically in the range of 100 nm in one dimension. While theories still lack the ability to explain empirical evidence for formation of stable NBs in water, numerous NB applications have emerged in different fields, including water and wastewater purification where NBs offer the potential to replace or improve efficiency of current treatment processes. The United Nations identifies access to safe drinking water as a human right, and municipal and industrial wastewaters require purification before they enter water bodies. These protections require treatment technologies to remove naturally occurring (e.g., arsenic, chromium, fluoride, manganese, radionuclides, salts, selenium, natural organic matter, algal toxins), or anthropogenic (e.g., nitrate, phosphate, solvents, fuel additives, pharmaceuticals) chemicals and particles (e.g., virus, bacteria, oocysts, clays) that cause toxicity or aesthetic problems to make rivers, lakes, seawater, groundwater, or wastewater suitable for beneficial use or reuse in complex and evolving urban and rural water systems. NBs raise opportunities to improve current or enable new technologies for producing fewer byproducts and achieving safer water. This account explores the potential to exploit the unique properties of NBs for improving water treatment by answering key questions and proposing research opportunities regarding (1) observational versus theoretical existence of NBs, (2) ability of NBs to improve gas transfer into water or influence gas trapped on particle surfaces, (3) ability to produce quasi-stable reactive oxygen species (ROS) on the surface of NBs to oxidize pollutants and pathogens in water, (4) ability to improve particle aggregation through intraparticle NB bridging, and (5) ability to mitigate fouling on surfaces. We conclude with key insights and knowledge gaps requiring research to advance the use of NBs for water purification. Among the highest priorities is to develop techniques that measure NB size and surface properties in complex drinking and wastewater chemistries, which contain salts, organics, and a wide variety of inorganic and organic colloids. In the authors' opinion, ROS production by NB may hold the greatest promise for usage in water treatment because it allows movement away from chemical-based oxidants (chlorine, ozone) that are costly, dangerous to handle, and produce harmful byproducts while helping achieve important treatment goals (e.g., destruction of organic pollutants, pathogens, biofilms). Because of the low chemical requirements to form NBs, NB technologies could be distributed throughout rapidly changing and increasingly decentralized water treatment systems in both developed and developing countries.

Development of a standardized food model for studying the impact of food matrix effects on the gastrointestinal fate and toxicity of ingested nanomaterials

Food matrix effects impact the bioavailability and toxicity of pharmaceuticals, nutraceuticals, pesticides, and engineered nanomaterials (ENMs). However, there are currently no standardized food models to test the impact of food matrix effects using in vitro gastrointestinal models. The purpose of this study was to establish a standardized food model (SFM) for evaluating the toxicity and fate of ingested ENMs and then to assess its efficacy by examining the impact of food matrix effects on the toxicity of TiO2 nanoparticles. The formulation of the SFM was based on the average composition of the US diet: 3.4% protein (sodium caseinate); 4.6% sugar (sucrose); 5.2% digestible carbohydrates (modified corn starch); 0.7% dietary fiber (pectin); 3.4% fat (corn oil); and, 0.5% minerals (sodium chloride). The SFM consisted of an oil-in-water emulsion suitable for use in both wet and dried forms. The dried form was produced by spray drying the emulsion to improve its handling and extend its shelf-life. The particle size (D32 = 135 nm), surface charge (-37.8 mV), viscosity, color (L*, a,* b* = 82.1, -2.5, 1.3), and microstructure of the wet SFM were characterized. The hydration properties, flowability (repose angle ≈ 27.9°; slide angle ≈ 28.2°), and moisture sorption isotherms of the dry SFM were comparable to commercial food powders. The potential gastrointestinal fate of the SFM was determined using a simulated gastrointestinal tract, including mouth, stomach, and small intestine steps. Conversion of the SFM into a powdered form did not impact its gastrointestinal fate. A nanotoxicology case study with TiO2 nanoparticles exposed to a tri-culture epithelial cell model showed that food matrix effects reduced ENM cytotoxicity more than 5-fold. The SFM developed in the current study could facilitate studies of the impact of food matrix effects on the gastrointestinal fate and toxicity of various types of food NPs.

A nano-carrier platform for the targeted delivery of nature-inspired antimicrobials using Engineered Water Nanostructures for food safety applications

Despite the progress in the area of food safety, foodborne diseases still represent a massive challenge to the public health systems worldwide, mainly due to the substantial inefficiencies across the farm-to-fork continuum. Here, we report the development of a nano-carrier platform, for the targeted and precise delivery of antimicrobials for the inactivation of microorganisms on surfaces using Engineered Water Nanostructures (EWNS). An aqueous suspension of an active ingredient (AI) was used to synthesize iEWNS, with the 'i' denoting the AI used in their synthesis, using a combined electrospray and ionization process. The iEWNS possess unique, active-ingredient-dependent physicochemical properties: i) they are engineered to have a tunable size in the nanoscale; ii) they have excessive electric surface charge, and iii) they contain both the reactive oxygen species (ROS) formed due to the ionization of deionized (DI) water, and the AI used in their synthesis. Their charge can be used in combination with an electric field to target them onto a surface of interest. In this approach, a number of nature-inspired antimicrobials, such as H₂O₂, lysozyme, citric acid, and their combination, were used to synthesize a variety of iEWNS-based nano-sanitizers. It was demonstrated through foodborne-pathogen-inactivation experiments that due to the targeted and precise delivery, and synergistic effects of AI and ROS incorporated in the iEWNS structure, a pico- to nanogram-level dose of the AI delivered to the surface using this nano-carrier platform is capable of achieving 5-log reductions in minutes of exposure time. This aerosol-based, yet 'dry' intervention approach using iEWNS nano-carrier platform offers advantages over current 'wet' techniques that are prevalent commercially, which require grams of the AI to achieve similar inactivation, leading to increased chemical risks and chemical waste byproducts. Such a targeted nano-carrier approach has the potential to revolutionize the delivery of antimicrobials for sterilization in the food industry.

Therapeutics for Inflammatory-Related Diseases Based on Plasmon-Activated Water: A Review

It is recognized that the properties of liquid water can be markedly different from those of bulk one when it is in contact with hydrophobic surfaces or is confined in nano-environments. Because our knowledge regarding water structure on the molecular level of dynamic equilibrium within a picosecond time scale is far from completeness all of water's conventionally known properties are based on inert "bulk liquid water" with a tetrahedral hydrogen-bonded structure. Actually, the strength of water's hydrogen bonds (HBs) decides its properties and activities. In this review, an innovative idea on preparation of metastable plasmon-activated water (PAW) with intrinsically reduced HBs, by letting deionized (DI) water flow through gold-supported nanoparticles (AuNPs) under resonant illumination at room temperature, is reported. Compared to DI water, the created stable PAW can scavenge free hydroxyl and 2,2-diphenyl-1-picrylhydrazyl radicals and effectively reduce NO release from lipopolysaccharide-induced inflammatory cells. Moreover, PAW can dramatically induce a major antioxidative Nrf2 gene in human gingival fibroblasts. This further confirms its cellular antioxidative and anti-inflammatory properties. In addition, innovatively therapeutic strategy of daily drinking PAW on inflammatory-related diseases based on animal disease models is demonstrated, examples being chronic kidney disease (CKD), chronic sleep deprivation (CSD), and lung cancer.

Innovatively Therapeutic Strategy on Lung Cancer by Daily Drinking Antioxidative Plasmon-Induced Activated Water

Many human diseases are inflammation-related, such as cancer and those associated with aging. Previous studies demonstrated that plasmon-induced activated (PIA) water with electron-doping character, created from hot electron transfer via decay of excited Au nanoparticles (NPs) under resonant illumination, owns reduced hydrogen-bonded networks and physchemically antioxidative properties. In this study, it is demonstrated PIA water dramatically induced a major antioxidative Nrf2 gene in human gingival fibroblasts which further confirms its cellular antioxidative and anti-inflammatory properties. Furthermore, mice implanted with mouse Lewis lung carcinoma (LLC-1) cells drinking PIA water alone or together with cisplatin treatment showed improved survival time compared to mice which consumed only deionized (DI) water. With the combination of PIA water and cisplatin administration, the survival time of LLC-1-implanted mice markedly increased to 8.01 ± 0.77 days compared to 6.38 ± 0.61 days of mice given cisplatin and normal drinking DI water. This survival time of 8.01 ± 0.77 days compared to 4.62 ± 0.71 days of mice just given normal drinking water is statistically significant (p = 0.009). Also, the gross observations and eosin staining results suggested that LLC-1-implanted mice drinking PIA water tended to exhibit less metastasis than mice given only DI water.

Assessment of reactive oxygen species generated by electronic cigarettes using acellular and cellular approaches

Electronic cigarettes (e-cigs) have fast increased in popularity but the physico-chemical properties and toxicity of the generated emission remain unclear. Reactive oxygen species (ROS) are likely present in e-cig emission and can play an important role in e-cig toxicity. However, e-cig ROS generation is poorly documented. Here, we generated e-cig exposures using a recently developed versatile exposure platform and performed systematic ROS characterization on e-cig emissions using complementary acellular and cellular techniques: 1) a novel acellular Trolox-based mass spectrometry method for total ROS and hydrogen peroxide (H₂O₂) detection, 2) electron spin resonance (ESR) for hydroxyl radical detection in an acellular and cellular systems and 3) in vitro ROS detection in small airway epithelial cells (SAEC) using the dihydroethidium (DHE) assay. Findings confirm ROS generation in cellular and acellular systems and is highly dependent on the e-cig brand, flavor, puffing pattern and voltage. Trolox method detected a total of 1.2-8.9nmol H₂O_2eq./puff; H₂O₂ accounted for 12-68% of total ROS. SAEC cells exposed to e-cig emissions generated up to eight times more ROS compared to control. The dependency of e-cig emission profile on e-cig features and operational parameters should be taken into consideration in toxicological studies.

An integrated electrolysis - electrospray - ionization antimicrobial platform using Engineered Water Nanostructures (EWNS) for food safety applications

Engineered water nanostructures (EWNS) synthesized utilizing electrospray and ionization of water, have been, recently, shown to be an effective, green, antimicrobial platform for surface and air disinfection, where reactive oxygen species (ROS), generated and encapsulated within the particles during synthesis, were found to be the main inactivation mechanism. Herein, the antimicrobial potency of the EWNS was further enhanced by integrating electrolysis, electrospray and ionization of de-ionized water in the EWNS synthesis process. Detailed physicochemical characterization of these enhanced EWNS (eEWNS) was performed using state-of-the-art analytical methods and has shown that, while both size and charge remain similar to the EWNS (mean diameter of 13 nm and charge of 13 electrons), they possess a three times higher ROS content. The increase of the ROS content as a result of the addition of the electrolysis step before electrospray and ionization led to an increased antimicrobial ability as verified by E. coli inactivation studies using stainless steel coupons. It was shown that a 45-minute exposure to eEWNS resulted in a 4-log reduction as opposed to a 1.9-log reduction when exposed to EWNS. In addition, the eEWNS were assessed for their potency to inactivate natural microbiota (total viable and yeast and mold counts), as well as, inoculated E.coli on the surface of fresh organic blackberries. The results showed a 97% (1.5-log) inactivation of the total viable count, a 99% (2-log) reduction in the yeast and mold count and a 2.5-log reduction of the inoculated E.coli after 45 minutes of exposure, without any visual changes to the fruit. This enhanced antimicrobial activity further underpins the EWNS platform as an effective, dry and chemical free approach suitable for a variety of food safety applications and could be ideal for delicate fresh produce that cannot withstand the classical, wet disinfection treatments.

Nanofiller Presence Enhances Polycyclic Aromatic Hydrocarbon (PAH) Profile on Nanoparticles Released during Thermal Decomposition of Nano-enabled Thermoplastics: Potential Environmental Health Implications

Nano-enabled products are ultimately destined to reach end-of-life with an important fraction undergoing thermal degradation through waste incineration or accidental fires. Although previous studies have investigated the physicochemical properties of released lifecycle particulate matter (called LCPM) from thermal decomposition of nano-enabled thermoplastics, critical questions about the effect of nanofiller on the chemical composition of LCPM still persist. Here, we investigate the potential nanofiller effects on the profiles of 16 Environmental Protection Agency (EPA)-priority polycyclic aromatic hydrocarbons (PAHs) adsorbed on LCPM from thermal decomposition of nano-enabled thermoplastics. We found that nanofiller presence in thermoplastics significantly enhances not only the total PAH concentration in LCPM but most importantly also the high molecular weight (HMW, 4-6 ring) PAHs that are considerably more toxic than the low molecular weight (LMW, 2-3 ring) PAHs. This nano-specific effect was also confirmed during in vitro cellular toxicological evaluation of LCPM for the case of polyurethane thermoplastic enabled with carbon nanotubes (PU-CNT). LCPM from PU-CNT shows significantly higher cytotoxicity compared to PU which could be attributed to its higher HMW PAH concentration. These findings are crucial and make the case that nanofiller presence in thermoplastics can significantly affect the physicochemical and toxicological properties of LCPM released during thermal decomposition.

Preparation, characterization, and in vitro dosimetry of dispersed, engineered nanomaterials

Evidence continues to grow of the importance of in vitro and in vivo dosimetry in the hazard assessment and ranking of engineered nanomaterials (ENMs). Accurate dose metrics are particularly important for in vitro cellular screening to assess the potential health risks or bioactivity of ENMs. To ensure meaningful and reproducible quantification of in vitro dose, with consistent measurement and reporting between laboratories, it is necessary to adopt standardized and integrated methodologies for (i) generation of stable ENM suspensions in cell culture media; (ii) colloidal characterization of suspended ENMs, particularly of properties that determine particle kinetics in an in vitro system (size distribution and formed agglomerate effective density); and (iii) robust numerical fate and transport modeling for accurate determination of the ENM dose delivered to cells over the course of the in vitro exposure. Here we present an integrated comprehensive protocol based on such a methodology for in vitro dosimetry, including detailed standardized procedures for each of these three critical aims. The entire protocol requires ∼6-12 h to complete.

Nanotechnology to the rescue: using nano-enabled approaches in microbiological food safety and quality

Food safety and quality assurance is entering a new era. Interventions along the food supply chain must become more efficient in safeguarding public health and the environment and must address numerous challenges and new consumption trends. Current methods of microbial control to assure the safety of food and minimize microbial spoilage have each shown inefficiencies. Nanotechnology is a rapidly expanding area in the agri/feed/food sector. Nano-enabled approaches such as antimicrobial food-contact surfaces/packaging, nano-enabled sensors for rapid pathogen/contaminant detection and nano-delivered biocidal methods, currently on the market or at a developmental stage, show great potential for the food industry. Concerns on potential risks to human health and the environment posed by use of engineered nanomaterials (ENMs) in food applications must, however, be adequately evaluated at the developmental stage to ensure consumer's acceptance.

Buoyant Nanoparticles: Implications for Nano-Biointeractions in Cellular Studies

In the safety and efficacy assessment of novel nanomaterials, the role of nanoparticle (NP) kinetics in in vitro studies is often ignored although it has significant implications in dosimetry, hazard ranking, and nanomedicine efficacy. It is demonstrated here that certain nanoparticles are buoyant due to low effective densities of their formed agglomerates in culture media, which alters particle transport and deposition, dose-response relationships, and underestimates toxicity and bioactivity. To investigate this phenomenon, this study determines the size distribution, effective density, and assesses fate and transport for a test buoyant NP (polypropylene). To enable accurate dose-response assessment, an inverted 96-well cell culture platform is developed in which adherent cells are incubated above the buoyant particle suspension. The effect of buoyancy is assessed by comparing dose-toxicity responses in human macrophages after 24 h incubation in conventional and inverted culture systems. In the conventional culture system, no adverse effects are observed at any NP concentration tested (up to 250 μg mL(-1) ), whereas dose-dependent decreases in viability and increases in reactive oxygen species are observed in the inverted system. This work sheds light on an unknown issue that plays a significant role in vitro hazard screening and proposes a standardized methodology for buoyant NP assessments.

Optimization of a nanotechnology based antimicrobial platform for food safety applications using Engineered Water Nanostructures (EWNS)

A chemical free, nanotechnology-based, antimicrobial platform using Engineered Water Nanostructures (EWNS) was recently developed. EWNS have high surface charge, are loaded with reactive oxygen species (ROS), and can interact-with, and inactivate an array of microorganisms, including foodborne pathogens. Here, it was demonstrated that their properties during synthesis can be fine tuned and optimized to further enhance their antimicrobial potential. A lab based EWNS platform was developed to enable fine-tuning of EWNS properties by modifying synthesis parameters. Characterization of EWNS properties (charge, size and ROS content) was performed using state-of-the art analytical methods. Further their microbial inactivation potential was evaluated with food related microorganisms such as Escherichia coli, Salmonella enterica, Listeria innocua, Mycobacterium parafortuitum, and Saccharomyces cerevisiae inoculated onto the surface of organic grape tomatoes. The results presented here indicate that EWNS properties can be fine-tuned during synthesis resulting in a multifold increase of the inactivation efficacy. More specifically, the surface charge quadrupled and the ROS content increased. Microbial removal rates were microorganism dependent and ranged between 1.0 to 3.8 logs after 45 mins of exposure to an EWNS aerosol dose of 40,000 #/cm(3).

Development and characterization of an exposure platform suitable for physico-chemical, morphological and toxicological characterization of printer-emitted particles (PEPs)

An association between laser printer use and emissions of particulate matter (PM), ozone and volatile organic compounds has been reported in recent studies. However, the detailed physico-chemical, morphological and toxicological characterization of these printer-emitted particles (PEPs) and possible incorporation of engineered nanomaterials into toner formulations remain largely unknown. In this study, a printer exposure generation system suitable for the physico-chemical, morphological, and toxicological characterization of PEPs was developed and used to assess the properties of PEPs from the use of commercially available laser printers. The system consists of a glovebox type environmental chamber for uninterrupted printer operation, real-time and time-integrated particle sampling instrumentation for the size fractionation and sampling of PEPs and an exposure chamber for inhalation toxicological studies. Eleven commonly used laser printers were evaluated and ranked based on their PM emission profiles. Results show PM peak emissions are brand independent and varied between 3000 to 1 300 000 particles/cm³, with modal diameters ranging from 49 to 208 nm, with the majority of PEPs in the nanoscale (<100 nm) size. Furthermore, it was shown that PEPs can be affected by certain operational parameters and printing conditions. The release of nanoscale particles from a nano-enabled product (printer toner) raises questions about health implications to users. The presented PEGS platform will help in assessing the toxicological profile of PEPs and the link to the physico-chemical and morphological properties of emitted PM and toner formulations.

Real-Time Nanoparticle-Cell Interactions in Physiological Media by Atomic Force Microscopy

Particle-cell interactions in physiological media are important in determining the fate and transport of nanoparticles and biological responses to them. In this work, these interactions are assessed in real time using a novel atomic force microscopy (AFM) based platform. Industry-relevant CeO2 and Fe2O3 engineered nanoparticles (ENPs) of two primary particle sizes were synthesized by the flame spray pyrolysis (FSP) based Harvard Versatile Engineering Nanomaterials Generation System (Harvard VENGES) and used in this study. The ENPs were attached on AFM tips, and the atomic force between the tip and lung epithelia cells (A549), adhered on a substrate, was measured in biological media, with and without the presence of serum proteins. Two metrics were used to assess the nanoparticle cell: the detachment force required to separate the ENP from the cell and the number of bonds formed between the cell and the ENPs. The results indicate that these atomic level ENP-cell interaction forces strongly depend on the physiological media. The presence of serum proteins reduced both the detachment force and the number of bonds by approximately 50% indicating the important role of the protein corona on the particle cell interactions. Additionally, it was shown that particle to cell interactions were size and material dependent.

Mycobacteria inactivation using Engineered Water Nanostructures (EWNS)

Airborne transmitted pathogens such as Mycobacterium tuberculosis (Mtb) cause serious, often fatal infectious disease with enormous global health implications. Due to their unique cell wall and slow growth, mycobacteria are among the most resilient microbial forms. Herein we evaluate the ability of an emerging, chemical-free, nanotechnology-based method to inactivate M. parafortuitum (Mtb surrogate). This method is based on the transformation of atmospheric water vapor into engineered water nano-structures (EWNS) via electrospray. We demonstrate that the EWNS can interact with and inactivate airborne mycobacteria, reducing their concentration levels significantly. Additionally, EWNS can inactivate M. parafortuitum on surfaces eight times faster than the control. The mechanism of mycobacteria inactivation was also investigated in this study. It was demonstrated that the EWNS effectively deliver the reactive oxygen species, encapsulated during the electrospray process, to the bacteria oxidizing their cell membrane resulting into inactivation. Overall, this is a method with the potential to become an effective intervention technology in the battle against airborne infections.

FROM THE CLINICAL EDITOR

This study demonstrates the feasibility of mycobacterium inactivation in airborne form or on contact surfaces using electrospray activated water nano-structures. Given that the method is free of toxic chemicals, this might become an important tool in the prevention of mycobacterial infections, which are notoriously hard to treat.