Dual Antibacterial Properties of Copper-Coated Nanotextured Stainless Steel.

Bacterial adhesion to stainless steel, an alloy commonly used in shared settings, numerous medical devices, and food and beverage sectors, can give rise to serious infections, ultimately leading to morbidity, mortality, and significant healthcare expenses. In this study, Cu-coated nanotextured stainless steel (nSS) fabrication have been demonstrated using electrochemical technique and its potential as an antibiotic-free biocidal surface against Gram-positive and negative bacteria. As nanotexture and Cu combine for dual methods of killing, this material should not contribute to drug-resistant bacteria as antibiotic use does. This approach involves applying a Cu coating on nanotextured stainless steel, resulting in an antibacterial activity within 30 min. Comprehensive characterization of the surface revealing that the Cu coating consists of metallic Cu and oxidized states (Cu2+ and Cu+), has been performed by this study. Cu-coated nSS induces a remarkable reduction of 97% in Gram-negative Escherichia coli and 99% Gram-positive Staphylococcus epidermidis bacteria. This material has potential to be used to create effective, scalable, and sustainable solutions to prevent bacterial infections caused by surface contamination without contributing to antibiotic resistance.

Chemical and biological conjugation strategies for the development of multivalent protein vaccine nanoparticles.

The development of subunit vaccine platforms has been of considerable interest due to their good safety profile and ability to be adapted to new antigens, compared to other vaccine typess. Nevertheless, subunit vaccines often lack sufficient immunogenicity to fully protect against infectious diseases. A wide variety of subunit vaccines have been developed to enhance antigen immunogenicity by increasing antigen multivalency, as well as stability and delivery properties, via presentation of antigens on protein nanoparticles. Increasing multivalency can be an effective approach to provide a potent humoral immune response by more strongly engaging and clustering B cell receptors (BCRs) to induce activation, as well as increased uptake by antigen presenting cells and their subsequent T cell activation. Proper orientation of antigen on protein nanoparticles is also considered a crucial factor for enhanced BCR engagement and subsequent immune responses. Therefore, various strategies have been reported to decorate highly repetitive surfaces of protein nanoparticle scaffolds with multiple copies of antigens, arrange antigens in proper orientation, or combinations thereof. In this review, we describe different chemical bioconjugation methods, approaches for genetic fusion of recombinant antigens, biological affinity tags, and enzymatic conjugation methods to effectively present antigens on the surface of protein nanoparticle vaccine scaffolds.

ISCOMs/MPLA-Adjuvanted SDAD Protein Nanoparticles Induce Improved Mucosal Immune Responses and Cross-Protection in Mice.

The epidemics caused by the influenza virus are a serious threat to public health and the economy. Adding appropriate adjuvants to improve immunogenicity and finding effective mucosal vaccines to combat respiratory infection at the portal of virus entry are important strategies to boost protection. In this study, a novel type of core/shell protein nanoparticle consisting of influenza nucleoprotein (NP) as the core and NA1-M2e or NA2-M2e fusion proteins as the coating antigens by SDAD hetero-bifunctional crosslinking is exploited. Immune-stimulating complexes (ISCOMs)/monophosphoryl lipid A (MPLA) adjuvants further boost the NP/NA-M2e SDAD protein nanoparticle-induced immune responses when administered intramuscularly. The ISCOMs/MPLA-adjuvanted protein nanoparticles are delivered through the intranasal route to validate the application as mucosal vaccines. ISCOMs/MPLA-adjuvanted nanoparticles induce significantly strengthened antigen-specific antibody responses, cytokine-secreting splenocytes in the systemic compartment, and higher levels of antigen-specific IgA and IgG in the local mucosa. Meanwhile, significantly expanded lung resident memory (RM) T and B cells (TRM /BRM ) and alveolar macrophages population are observed in ISCOMs/MPLA-adjuvanted nanoparticle-immunized mice with a 100% survival rate after homogeneous and heterogeneous H3N2 viral challenges. Taken together, ISCOMs/MPLA-adjuvanted protein nanoparticles could improve strong systemic and mucosal immune responses conferring protection in different immunization routes.

Surface Engineering of Protein Nanoparticles Modulates Transport, Adsorption, and Uptake in Mucus.

Protein nanoparticles have been demonstrated as effective carriers for protein antigens and therapeutics due to properties endowed by their protein composition. They exhibit high protein to carrier yields, biocompatibility, and heterogeneous surface properties. While protein nanoparticles have been delivered via multiple routes, including intranasal, their interactions with mucosal barriers have not been well studied or modified. Biological barriers associated with intranasal delivery consist of viscoelastic mucus that hinders material transport through surface interactions and the underlying epithelium. Herein, we altered protein nanoparticle surface properties and characterized interactions with nasal mucus and the subsequent effects on diffusion, cellular uptake, and immune cell maturation. Ovalbumin protein nanoparticles were used, serving as a model vaccine nanoparticle. Unmodified ovalbumin protein nanoparticles were compared to cationic ovalbumin particles functionalized with amine groups, neutral particles functionalized with polyethylene glycol, and zwitterionic particles coated layer-by-layer (LBL) with chitosan and oligonucleotides. Transport analysis indicated rapid diffusion of polyethylene glycol and LBL-modified ovalbumin nanoparticles in porcine nasal mucus, while cationic particles were mucoadhesive. Cellular uptake in the presence of mucus by epithelial and dendritic cells was highest for particles containing positive charges, both LBL and amine-functionalized. These particles also exhibited the most diverse adsorbed protein corona from nasal fluids. The corona impacted both dendritic cell uptake and maturation, with polyethylene glycol and LBL modifications improving CD86 expression. Altogether, surface modifications on protein-based nanocarriers are shown to facilitate distinctive physical and cellular behavior associated with mucosal delivery.

Automation and low-cost proteomics for characterization of the protein corona: experimental methods for big data.

Nanoparticles used in biological settings are exposed to proteins that adsorb on the surface forming a protein corona. These adsorbed proteins dictate the subsequent cellular response. A major challenge has been predicting what proteins will adsorb on a given nanoparticle surface. Instead, each new nanoparticle and nanoparticle modification must be tested experimentally to determine what proteins adsorb on the surface. We propose that any future predictive ability will depend on large datasets of protein-nanoparticle interactions. As a first step towards this goal, we have developed an automated workflow using a liquid handling robot to form and isolate protein coronas. As this workflow depends on magnetic separation steps, we test the ability to embed magnetic nanoparticles within a protein nanoparticle. These experiments demonstrate that magnetic separation could be used for any type of nanoparticle in which a magnetic core can be embedded. Higher-throughput corona characterization will also require lower-cost approaches to proteomics. We report a comparison of fast, low-cost, and standard, slower, higher-cost liquid chromatography coupled with mass spectrometry to identify the protein corona. These methods will provide a step forward in the acquisition of the large datasets necessary to predict nanoparticle-protein interactions.

Nanoscale battery cathode materials induce DNA damage in bacteria.

The increasing use of nanoscale lithium nickel manganese cobalt oxide (Li x Ni y Mn z Co1-y-z O2, NMC) as a cathode material in lithium-ion batteries poses risk to the environment. Learning toxicity mechanisms on molecular levels is critical to promote proactive risk assessment of these complex nanomaterials and inform their sustainable development. We focused on DNA damage as a toxicity mechanism and profiled in depth chemical and biological changes linked to DNA damage in two environmentally relevant bacteria upon nano-NMC exposure. DNA damage occurred in both bacteria, characterized by double-strand breakage and increased levels of many putative chemical modifications on bacterial DNA bases related to direct oxidative stress and lipid peroxidation, measured by cutting-edge DNA adductomic techniques. Chemical probes indicated elevated intracellular reactive oxygen species and transition metal ions, in agreement with DNA adductomics and gene expression analysis. By integrating multi-dimensional datasets from chemical and biological measurements, we present rich mechanistic insights on nano-NMC-induced DNA damage in bacteria, providing targets for biomarkers in the risk assessment of reactive materials that may be extrapolated to other nano-bio interactions.

Biological impact of nanoscale lithium intercalating complex metal oxides to model bacterium B. subtilis.

The wide applications of lithium intercalating complex metal oxides in energy storage devices call for a better understanding of their environmental impact at the end of their life cycle. In this study, we examine the biological impact of a panel of nanoscale lithium nickel manganese cobalt oxides (Li x Ni y Mn z Co1-y-z O2, 0 < x, y, z < 1, abbreviated to NMCs) to a model Gram-positive bacterium, Bacillus subtilis, in terms of cellular respiration and growth. A highly sensitive single-cell gel electrophoresis method is also applied for the first time to understand the genotoxicity of these nanomaterials to bacterial cells. Results from these assays indicate that the free Ni and Co ions released from the incongruent dissolution of the NMC material in B. subtilis growth medium induced both hindered growth and cellular respiration. More remarkably, the DNA damage induced by the combination of the two ions in solution is comparable to that induced by the NMC material, which suggests that the free Ni and Co ions are responsible for the toxicity observed. A material redesign by enriching Mn is also presented. The combined approaches of evaluating their impact on bacterial growth, respiration, and DNA damage at a single-cell level, as well as other phenotypical changes allows us to probe the nanomaterials and bacterial cells from a mechanistic prospective, and provides a useful means to an understanding of bacterial response to new potential environmental stressors.

Coating iron oxide nanoparticles with mesoporous silica reduces their interaction and impact on S. oneidensis MR-1.

Here, we investigate the impact of iron oxide nanoparticles (IONPs) and mesoporous silica-coated iron oxide nanoparticles (msIONPs) on Shewanella oneidensis in an aerobic environment, which is likely the main environment where such nanoparticles will end up after use in consumer products or biomedical applications. Monitoring the viability of S. oneidensis, a model environmental organism, after exposure to the nanoparticles reveals that IONPs promote bacterial survival, while msIONPs do not impact survival. These apparent impacts are correlated with association of the nanoparticles with the bacterial membrane, as revealed by TEM and ICP-MS studies, and upregulation of membrane-associated genes. However, similar survival in bacteria was observed when exposed to equivalent concentrations of released ions from each nanomaterial, indicating that aqueous nanoparticle transformations are responsible for the observed changes in bacterial viability. Therefore, this work demonstrates that a simple mesoporous silica coating can control the dissolution of the IONP core by greatly reducing the amount of released iron ions, making msIONPs a more sustainable option to reduce perturbations to the ecosystem upon release of nanoparticles into the environment.