Multidrug-resistant (MDR) Salmonella enterica serovar Typhimurium (S. Typhimurium) poses a growing threat to food safety and animal health, particularly in the swine industry. In this study, we characterized a highly resistant ST strain isolated from a Quebec swine farm using whole-genome sequencing and phenotypic assays. The isolate harbored two plasmids, one of which encoded resistance to seven major antibiotic classes, including β-lactams, aminoglycosides, and sulfonamides, along with multiple virulence factors. To counteract these resistance mechanisms, we developed a nano-enabled antibacterial combination therapy (NeACT) by co-encapsulating amoxicillin (AMOX) and the β-lactamase inhibitor tazobactam into cyclodextrin encapsulated in liposomes (LP-CAT). Physicochemical analysis confirmed optimal particle size, charge, and stability, while checkerboard assays demonstrated strong drug synergism. The LP-CAT formulation drastically restored antimicrobial efficacy, reducing the AMOX minimum inhibitory concentration (MIC) from >2000 µg/mL to ~60 µg/mL. Using porcine intestinal epithelial (IPEC-J2) cells as an intracellular infection model, our study showed the potential of LP-CAT to remove >94% of intracellular bacteria with no cytotoxic effect. The ability of LP-CAT to resolve intestinal infection was further verified in Caenorhabditis elegans (C. elegans) intestinal infection model. These findings establish LP-CAT as a safe and effective strategy to revive antibiotic potency against intracellular MDR pathogens, offering a novel tool for combating antimicrobial resistance in livestock and safeguarding public health.

Contemporary research in food packaging is focused on developing sustainable alternatives to petroleum-based materials. Pullulan, a microbial biopolymer traditionally employed as a food additive, is harnessing interest for food packaging applications due to its exceptional film-forming ability, biodegradability, and nontoxic nature. However, there are key limitations associated with the cost of production and suboptimal physicochemical attributes (e.g., inadequate water barrier and mechanical strength) that curtail the successful industrial translation of pullulan as a packaging polymer. Accordingly, this review examines effective ways for boosting biosynthetic efficiency of pullulan production through genetic and metabolic engineering of native strains and identifies emerging strategies such as targeted chemical modifications, electrospinning, incorporation of bioactive compounds, and film casting to enhance properties of pullulan-based packaging materials. Encapsulation strategies for bioactive substances are emphasized in pullulan-based active packaging for controlled release and sustained efficacy, whereas integration with pH-responsive sensing entities enables smart packaging for real-time freshness monitoring of protein-rich foods. Further, we examined regulatory and safety frameworks, providing a perspective that bridges innovation with compliance requirements for commercial deployment. All in all, this review demonstrates the potential to reduce production costs and improve film properties, which has significantly strengthened the prospects of pullulan as a sustainable, biopolymer-based alternative to synthetic materials.

Bovine mastitis (BM), resulting from intramammary infection, is one of the costliest diseases in animal agriculture. Occasional treatment failure and bacterial persistence in the mammary gland demand alternate therapeutic approaches. Nanotechnology-enabled Antibacterial Combination Therapy (NeACT), which utilizes nanomaterials to co-deliver more than one drug molecule with synergistic and complementary antibacterial mechanisms, holds promise for BM treatment. Here, we developed a NeACT constituting ceftiofur (CF) loaded chitosan nanoparticles conjugated with chlorpromazine (CPZ) and tannic acid (TA) loaded cyclodextrin nanoparticles. CF, CPZ, and TA showed a synergistic antibacterial action (FICI = 0.49) against a methicillin-resistant Staphylococcus aureus strain (Sa1158c) isolated from BM. NeACT demonstrated colloidal stability, biocompatibility, and slow-release of payloads and showed a significant reduction in Sa1158c efflux pump (by ∼15.53-fold) and biofilm-forming (by ∼3.40 log10) abilities. It showed low immunogenicity and no adverse effect on the mammary tissues of CD-1 lactating mice in a mastitis model. NeACT of ≥3.90 µg mL-1 demonstrated ≥3.20 log10 reduction of internalized Sa1158c in epithelial cells in vitro, while NeACT of 39 µg per gland showed ≥4.46 log10 remediation of Sa1158c from infected mice. Overall, NeACT successfully reduced the effective concentration of CF, CPZ, and TA and overcame Sa1158c CF resistance. These desirable therapeutic characteristics warrant its application for treating BM.

Visualizing three-dimensional (3D) microstructures of complex biological tissues is crucial for understanding disease progression and environmental stress responses. Here, we report a modified workflow of synchrotron micro-computed tomography (SR-μCT) phase-contrast imaging (PCI) for 3D histology of colon biopsies from ulcerative colitis patients in remission (UCr), by refining the sample preparation method and data processing for improved image quality and processing of large synchrotron datasets. Our studies showed that samples prepared by critical-point-dried (CPD) markedly enhanced intrinsic contrast relative to paraffin-embedded specimens, enabling delineation of tissue microarchitecture and the reliability of digital segmentation. Additionally, we developed a scalable data orchestration workflow (Tiffy McSliceface, TMSF) that enabled segmentation of full-resolution volumetric datasets through structured sparse annotation and smart interpolation. This approach eliminates the need for binning, cropping, or bit-depth reduction, thereby improving processing speed and overall efficiency. As a proof-of-concept, we employed the proposed workflow for SR-μCT-PCI to visualize and quantify microstructural alterations in biopsies exposed to the food additive titanium dioxide (E171) ex vivo, revealing disrupted 3D crypt lumen interconnectivity. In short, our studies showed the possibility of simplifying large synchrotron data processing and supports high-throughput 3D analysis for investigating gastrointestinal pathology and tissue responses to environmental stressors.

Increasingly a source of water for irrigation, wastewater (WW) poses risks to crops due to potential contaminants. It can harbor metals and organic contaminants known to impact harmfully on human and environmental health. Nanoparticles (NPs) detected in wastewater raises questions about their possible interactions with cocontaminants, and their effects on soil-water systems (e.g., WW-irrigated agriculture). Titanium dioxide nanoparticles (TiO2 NPs), commonly found in industrial and consumer products and observed in wastewater, could potentially influence the mobility of soil contaminants and metal uptake by crops. Accordingly, we conducted a two-year (2017 and 2018) field lysimeter study to investigate the impacts of titanium dioxide nanoparticles on the mobility of metals (Cd, Cr, Cu, Fe, Pb and Zn) and their uptake by potato plants (Solanum tuberosum L. cv. 'Russet Burbank'). The potatoes, grown in sandy soil under controlled conditions, were irrigated with synthetic wastewater (WW), or with wastewater + titanium dioxide nanoparticles (WW+TiO2 NPs). At harvest, the potato tubers, plant parts and soil samples were analyzed for their metal concentrations. The presence of 1 mg L- 1 TiO2 NPs in the irrigation wastewater significantly reduced the uptake of cadmium, copper and zinc by the potato flesh, skin and roots in both treatment years (p <= 0.05), but did not significantly change the uptake of chromium, lead and iron into any plant parts. We conclude therefore that titanium dioxide nanoparticles in the wastewater appeared to reduce the bioavailability of cadmium, copper and zinc in the soil.

Contamination of aquatic and terrestrial ecosystems with microplastics (MPs) and nanoplastics (NPs) has raised significant global concerns. While most studies have focused on aquatic contamination, knowledge concerning the effect of MPs and NPs in biosolids on agricultural field crops remains limited, as is the range of polymer types tested. In this study, polyethylene nanoplastics (HDPE-NPs, <500 nm diameter) were produced in the lab, and their effect on tomato plants (Solanum lycopersicum L.) was studied at different growth stages. Physical and chemical characterizations of the HDPE-NPs were performed. Compared to the control group, the presence of 2.8 mg/kg HDPE-NPs in soil increased tomato leaf greenness (p < 0.05), while the presence of 0.5 mg/kg HDPE-NPs in the soil lowered water use efficiency (WUE, p < 0.05) of the plants in the early vegetative stage. Soil CO2 emissions were significantly lower under both the 0.5 mg/kg (p < 0.05) and 2.8 mg/kg HDPE-NPs treatments (p < 0.05). At the early germination stage, HDPE-NPs in the soil resulted in stunted seedlings (p < 0.001). Moreover, the average fruit weight and number of fruits borne by mature plants were adversely affected, possibly because of potential alterations in soil nitrogen content and associated plant uptake pathways. A pattern of hormetic dose response was observed for some measured parameters, including leaf greenness, plant WUE, and soil CO2 emissions, although the underlying mechanisms remain unclear. Overall, the range between 1 and 5 mg/kg concentration of HDPE-NPs in soil was found to have the greatest impact on tomato plants, while other factors may contribute to the observed effects.

CdSe/ZnS-based quantum dots (QDs) are being increasingly applied in many electronic devices, raising concerns over the ecotoxicity of QDs released into the environment during the end-of-life of such devices. Most (eco)toxicity studies have used pristine QDs with noncommercially relevant coatings or omitted their environmental transformation. We used CdSe/ZnS QDs coated with polyethylenimine, similar to those found in TV screens to examine their transformation and toxicity when aged in the presence of humic acid and/or light. The transformed samples were exposed to Chlorella vulgaris to assess impacts of different aging conditions on oxidative stress and growth inhibition. Light exposure enhanced the dissolution of pristine QDs and the release of Zn and Cd which was 5-10 folds higher than those released under dark conditions. Presence of humic acid, however, decreased the dissolution of QDs when exposed to light because of the light shielding and ion-scavenging effects of humic acid. Pristine QDs aggregated with the algae, which, when exposed to light, caused dissolution and release of metal ions locally around algae cells, causing significant loss of cell viability. However, humic acid in QD exposure media reduced oxidative stress and cell viability loss (by 2.5- fold) as it reduced bioavailability of both QDs and heavy metal ions. These findings highlight the significance of understanding the relationship between environmental transformation and ecotoxicity of QDs.

AIM:This study aims to develop a nanocarrier system for the oral delivery of β-Carotene (BC) (as a model therapeutic agent) and to test its efficacy in ameliorating inflammation in an ulcerative colitis (UC) patient-derived organoid. MATERIALS & METHODS:BC was encapsulated in a zein protein nano-cage surface-functionalized with pectin and polyethyleneglycol (PEG). The nanoencapsulated BC (nBC) was characterized for physicochemical properties (size, charge, surface chemistry) and functional properties (radical scavenging, mucoadhesion and penetration, release in simulated digestive fluids). Further, we evaluated the performance of nBC in ameliorating inflammation in Caco-2 and UC patient-derived organoid models. RESULTS:nBC achieved 75% encapsulation efficiency with improved stability and functional properties when compared to free BC. The nanocarrier was non-cytotoxic and improved mucoadhesion, mucopenetration, and the anti-inflammatory potential of BC. In UC organoids, nBC suppressed dextran sulfate sodium (DSS)-induced TNF-α and IL-8 production by approximately 70% and 31%, respectively, which was significantly higher than free BC at comparable concentrations. CONCLUSIONS:The protein-polymer nanoencapsulation strategy showed promise in protecting BC and overcoming intestinal mucus barriers for an improved anti-inflammatory effect in the organoid model. Further studies using animal models are warranted for establishing pharmacokinetics, tissue distribution, and therapeutic index of orally delivered nBC.

Cannabis plants are susceptible to microbial contamination, including fungi capable of producing harmful mycotoxins. The presence of these toxins in cannabis products poses serious health risks, especially when used for medical purposes in immunocompromised people. This study evaluated the presence of fungi and mycotoxins in dried cannabis buds following gamma irradiation, using culture-based techniques, PCR/qPCR, and ELISA. Irradiation significantly reduced fungal and bacterial loads, eliminating culturable bacteria but did not achieve complete sterilization. Viable spores of toxigenic fungal genera, such as Aspergillus, Penicillium, and Fusarium, persisted. Sequencing of ITS amplicons revealed dominant mycotoxigenic fungi in non-irradiated (NR), irradiated (IR) and licensed producer (LP) samples, while next-generation sequencing (NGS) revealed additional non-culturable toxigenic species. PCR/qPCR detected biosynthetic genes for aflatoxins, trichothecenes, ochratoxins, and deoxynivalenol across all samples, with gene copy numbers remaining stable post-irradiation, suggesting DNA damage without full degradation. ELISA confirmed aflatoxin, ochratoxin, DON, and T2 toxins in both IR and LP samples at variable concentrations. While LP samples showed lower microbial counts and gene abundance, residual DNA and toxins were still detected. Our study shows that while irradiation decreases microbial loads, it does not completely remove toxigenic fungi or their metabolites. Ensuring the safety of cannabis products necessitates a multifaceted assessment that incorporates cultural, molecular, and immunological techniques, in parallel with more stringent microbial standards during production stage.

Nanomaterials (NMs) entering the human body via the oral route are subjected to successive digestive chambers in the gastrointestinal (GI) tract, which could alter their physicochemical properties and toxicity profile....

Unique outcomes ensuing nanomaterial (NM) interactions with discrete wavelengths of electromagnetic radiation have been utilized in various biological applications. We investigated the antibacterial effect and dissolution of five NMs (gold nanospheres (AuNSs), two gold nanorods (AuNRs636 and AuNRs772), silver nanoparticles (AgNPs), and titanium dioxide nanoparticles (TiO2 NPs)) in saline and milk during microwave (MW) treatment. AuNSs, AgNPs, AuNRs636, and AuNRs772 improved the antibacterial effect of MW not only by increasing the temperature of the suspending media but also due to oxidative stress. Notably, the damage to bacterial membrane, measured as a reduction in the membrane potential, and reactive oxygen species generation in Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria was higher during MW treatment in the presence of AuNRs in comparison to AuNSs. AuNRs636 (4 µg/mL) combined with MW (40 s) achieved 5 Log10(CFU/mL) reduction of E. coli and S. aureus in milk. MW enhanced the dissolution of AuNRs636 in milk, while AgNPs and TiO2 NPs showed aggregation after MW. Apart from elucidating the increased temperature and oxidative stress on bacterial elimination, this work highlighted the differential effects of MW on NMs of different chemical composition and shape.

A 2-year (2017 and 2018) field lysimeter study was carried out to examine the effect of titanium dioxide nanoparticles (TiO2 NPs) in irrigation wastewater on soil characteristics and potato (Solanum tuberosum L.) yield. Potatoes were planted in lysimeters (1.00 m × 0.45 m) in sandy soil and subjected to four treatments: freshwater (FW), wastewater (WW), freshwater + TiO2 NPs (FW + NP) and wastewater + TiO2 NPs (WW + NP), in triplicate. Potato tubers were harvested at maturity (120 days after planting). Both the TiO2 NPs (with/without 1 mg L−1 TiO2 NPs) and irrigation treatments (FW vs. WW) had a significant effect (p ≤ 0.05) on chlorophyll content; however, they had little or no effect on soil physicochemical parameters (cation exchange capacity (CEC), pH and soil organic matter (SOM)), plant growth parameters (plant height, above-ground and root fresh weight) or yield (tuber weight, number of tubers and tuber grading). For both years, the total nitrogen content of the leaves increased consistently together with leaf chlorophyll content. Furthermore, tuber yield under FW, WW and WW + NP treatments were higher in the first year than in the second, likely due to higher growing season temperatures in the second year. This study furthers the knowledge on the impact of TiO2 NPs on plant growth by showing that at 1 mg L−1, irrigation water can increase greenness without inhibiting plant growth and yield. In addition, the potato plants, irrigated with water containing TiO2 NPs, did not become infected with early and late blight diseases either year.

Levans of different structures and molecular weights (MW) can display various techno-functional and health-promoting properties. In the present study, selected levans were produced by the transfructosylation of sucrose catalyzed by levansucrases from Bacillus amyloliquefaciens and Gluconobacter oxydans, and their structural, techno-functional and anti-inflammatory properties were investigated. NMR and methylation/GC analysis confirmed the structure of β-(2, 6) levans. The structural characterization led to the classification of levans as high MW (HMW, ≥100 kDa), low MW (LMW, ≤20 kDa) and mix L/HMW ones. Levan with higher MW had more linear fructosyl units with fewer reducing ends and branching residues. LMW levan showed the highest foaming capacity and stability while HMW levan had the highest emulsion stability. HMW and mix L/HMW levans showed comparable water and oil-holding capacities, which were higher than LMW. HMW and mix L/HMW levans were found to have gelling properties at low concentrations. The rheological behaviour of HMW levan-based gel was a more viscous-like gel, while that of mix L/HMW levan-based one showed more elastic solid like-gel. The temperature also influenced the rheology of levan, showing that the mix L/HMW levan gel network was the most thermal stable as its viscoelasticity remained constant at the highest temperature (75 °C). Studies on the biological activity of levans of HMW and LMW revealed in-vitro anti-inflammatory properties as they significantly reduced the production of LPS-triggered pro-inflammatory cytokines in differentiated Caco-2 cells.

Synthetic polymers used for food packaging contribute to plastic pollution due to poor degradability. While they prevent the entry of microorganisms, they may not protect against spoilage microorganisms in the packed food. Nanofillers have been used to improve such properties, but end-of-life degradation remains an issue, making plastic a persistent pollutant. Here, we tested a nanocomposite (Nc) of tannic acid-loaded halloysite nanotubes grafted with silver nanoparticles as a reinforcement to enhance the mechanical, antimicrobial, and degradation properties of Linear low-density polyethylene (LLDPE) films. LLDPE films incorporated with Nc significantly improved tensile strength (TS), elongation at break (EB), and oxygen permeability rate. Nc incorporated (at 5%and 10%) LLDPE films exhibited a 1.89-2.85 log10 reduction in multi-drug resistant Staphylococcus aureus 1158c in chicken fillets. Both film types demonstrated silver migration below the European Food Safety Authoritymandated acceptable limit. Nc/LLDPE films disintegrated faster when exposed to incandescent light for 6 h, evidenced by significant reduction of weight, TS, and EB. Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy suggested oxidative degradation and breakdown of the polymer. Conclusively, Nc improved the functional properties and degradation rate of LLDPE films when exposed to light, showing potential for enhancing the sustainability of synthetic polymers.

Polyethylene Terephthalate (PET) is a type of plastic largely used for packing food and beverages. Unfortunately, it includes a major portion of the plastic distributed through aquatic systems wherever systematic collection and recycling are lacking. Although PET is known to be non-toxic, it is not obvious whether the nanoparticles (NPs) formed due to their degradation have any direct/indirect effect on aquatic organisms. In order to study the effects on aquatic environment, fresh water algae Chlorella vulgaris was subjected to incremental concentrations of the NPs. We observed a concentration and duration of exposure dependent decrease in algal growth rate along with reduced total chlorophyll content. Scanning electron microscopy revealed deformities in cell shape and the uptake of Propidium Iodide suggested membrane damage in response to NP exposure. Intracellular Reactive Oxygen Species level was also found significantly higher, evidenced by Dichlorodihydrofluorescein diacetate staining. Activity of antioxidant enzymes Superoxide dismutase (SOD), Peroxidase (POD) and Catalase (CAT) were significantly higher in the NP exposed groups suggesting the cellular response to regain homeostasis. Further, expression levels of the genes psaB, psbC, and rbcL associated with photosynthesis increased above two fold with respect to the control inferring the possibility of damage to photosynthesis and the initial molecular responses to circumvent the situation. In short, our studies provide evidence for oxidative stress mediated cellular damages in Chlorella vulgaris exposed to NPs of PET.

Widespread applications and release of photoactive nanoparticles (NPs) such as titanium dioxide (TiO2) into environmental matrices warrants mechanistic investigations addressing toxicity of NPs under environmentally relevant conditions. Accordingly, we investigated the effects of surface adsorbed NOMs (humic acid, tannic acid and lignin) on the band gap energy, abiotic reactive oxygen species (ROS) generation, surface chemistry and phototoxicity of TiO2 NPs. Initially, a liquid assisted grinding method was optimized to produce TiO2 NPs with a NOM layer of defined thickness for further analysis. Generally, adsorption of NOM reduced the band-gap energy of TiO2 NPs. Light activated ROS generation by TiO2 NPs, however, was reduced by the presence of NOM because of the decreased surface oxygen vacancy (as revealed by X-ray Photoelectron Spectroscopy (XPS)) and quenching of ROS by surface adsorbed NOM. Despite the reduced ROS generation, the NOM-modified TiO2 NPs exhibited an increased phototoxicity to Chlorella vulgaris in comparison to pristine TiO2 NPs. Further analysis suggested that photoactivation of NOM modified TiO2 NPs releases toxic degradation products. Findings from our studies thus provide mechanistic insight into the ecotoxic potential of NOM-modified TiO2 NPs when exposed to light in the environment.

Background Staphylococcus aureus is one of the prevalent etiological agents of contagious bovine mastitis, causing a significant economic burden on the global dairy industry. Given the emergence of antibiotic resistance (ABR) and possible zoonotic spillovers, S aureus from mastitic cattle pose threat to both veterinary and public health. Therefore, assessment of their ABR status and pathogenic translation in human infection models is crucial. Results In this study, 43 S. aureus isolates associated with bovine mastitis obtained from four different Canadian provinces (Alberta, Ontario, Quebec, and Atlantic provinces) were tested for ABR and virulence through phenotypic and genotypic profiling. All 43 isolates exhibited crucial virulence characteristics such as hemolysis, and biofilm formation, and six isolates from ST151, ST352, and ST8 categories showed ABR. Genes associated with ABR ( tetK, tetM, aac6’, norA, norB, lmrS , blaR, blaZ , etc.), toxin production ( hla, hlab , lukD , etc.), adherence ( fmbA, fnbB, clfA, clfB , icaABCD , etc.), and host immune invasion ( spa, sbi, cap, adsA , etc.) were identified by analyzing whole-genome sequences. Although none of the isolates possessed human adaptation genes, both groups of ABR and antibiotic-susceptible isolates demonstrated intracellular invasion, colonization, infection, and death of human intestinal epithelial cells (Caco-2), and Caenorhabditis elegans . Notably, the susceptibilities of S. aureus towards antibiotics such as streptomycin, kanamycin, and ampicillin were altered when the bacteria were internalized in Caco-2 cells and C. elegans . Meanwhile, tetracycline, chloramphenicol, and ceftiofur were comparatively more effective with ≤ 2.5 log 10 reductions of intracellular S. aureus . Conclusions This study demonstrated the potential of S. aureus isolated from mastitis cows to possess virulence characteristics enabling invasion of intestinal cells thus calling for developing therapeutics capable of targeting drug-resistant intracellular pathogens for effective disease management.

Inhalation of particulate matter (PM) present in indoor atmospheres has been associated with poor health and wellbeing of occupants. Here we report the characteristics of airborne PM collected from twenty-two air-conditioned childcare centres in Singapore. Airborne PM were collected using cascade impactors and characterized for morphology, elemental composition, endotoxin levels, ability to generate abiotic reactive oxygen species, and oxidative stress-dependent cytotoxicity in BEAS-2B cell lines. The mass concentrations of ultrafine particles (PM0.06-1) were more abundant than that of larger particles (PM1-4, PM4-20, and PM20-35 particles). PM20-35 and PM4-20 were irregularly shaped particles, PM1-4 particles had membranous flaky structures and PM0.06-1 particles were pseudo-spherical with the occasional presence of crystalline structures. Carbonaceous matter dominated PM20-35 particles, and the abundance of inorganic salts, iron and sulfur increased with decreasing PM size. Measured endotoxin levels were especially higher in PM4-20 particles. Compared to other particle size fractions, PM0.06-1 particles generated the highest ROS and were also the most potent in generating intracellular ROS in BEAS-2B cell lines. However, total mass concentrations, elemental compositions, abiotic responses, and PM collected from centres with split air-conditioning systems and no active outdoor air supply (SAC) were not statistically different compared with PM collected from centres with air conditioning with mechanical ventilation (ACMV). In conclusion, our study showed obvious distinctions in mass concentrations, morphology, elemental compositions, and cytotoxic potential of different sized particles collected from childcare centres, where the smallest particles (PM0.06-1) exhibited higher hazard potential.

Poor mechanical and water barrier properties restrict the applicability of protein-based packaging in high-moisture food commodities. In this study, a nanocomposite (Nc) of tannic acid-loaded halloysite nanotubes grafted with silver nanoparticles was developed as a reinforcement agent to enhance the functional properties of soy protein isolate (SPI)-based films. The 5%- and 10%-Nc incorporation in SPI films significantly (p<0.05) improved the tensile strength (by 1.94-3.14 fold) and thermal stability (by 5-7%) and reduced water vapor permeability (by 1.28-1.30 fold), oxygen permeability (by 2.72-3.84 fold), and water solubility (by 6.3-9.5 fold). The 5%- and 10% Nc/SPI films showed antioxidant properties (by scavenging 18%-28% of DPPH) and exhibited a 3-5 log10 reduction in multi-drug resistant S. aureus and S. Typhimurium contamination in chicken breast fillets. Although 10% Nc/SPI exhibited silver migration to chicken fillets beyond the acceptable limit contributing to color change, 5% Nc/SPI films enhanced the shelf-life of fillets for 4 days by facilitating a controlled pH, lipid oxidation, and microbial growth with acceptable levels of silver migration. In conclusion, the multifunctionality of Nc in SPI films enables its potential to be an alternative to non-biodegradable and non-eco-friendly polymers.

Inhalation of particulate matter (PM) present in indoor atmospheres has been associated with poor health and wellbeing of occupants. Here we report the characteristics of airborne PM collected from twenty-two air-conditioned childcare centres in Singapore. Airborne PM were collected using cascade impactors and characterized for morphology, elemental composition, endotoxin levels, ability to generate abiotic reactive oxygen species, and oxidative stress-dependent cytotoxicity in BEAS-2B cell lines. The mass concentrations of ultrafine particles (PM0.06-1) were more abundant than that of larger particles (PM1-4, PM4-20 and PM20-35 particles). PM20-35 and PM4-20 were irregularly shaped particles, PM1-4 had membranous flaky structures and PM0.06-1 were pseudo-spherical with the occasional presence of crystalline structures. Carbonaceous matter dominated PM20-35, and the abundance of inorganic salts, iron and sulfur increased with decreasing PM size. Measured endotoxin levels were especially higher in PM4-20 particles. Abiotic ROS generation and NF-κB activation in BEAS-2B cell lines were higher in PM0.06-1 particles while cell death was more prominent in PM4-20 particles. Notably, PM collected from centres with split air-conditioning systems and no active outdoor air supply were of higher mass concentrations and cytotoxicity, compared with PM collected from mechanically ventilated centres. In conclusion, our study showed obvious distinctions in mass concentrations, morphology, elemental compositions and cytotoxic potential of different sized particles collected from childcare centres, where the smallest particles (PM0.06-1) exhibited higher hazard potential.