Synthesis of Metal-Modified Nanocellulose as a Biofilm Analogue for Biofilm Mimicry in Biomedical and Environmental Applications.

Bacterial biofilms are complex, multi-component structures consisting primarily of four key elements: polysaccharides, metal ions, proteins, and extracellular DNA. In our research, we specifically focus on the polysaccharide and metal ion components, which play a crucial role in determining the biofilm's mechanical properties. Polysaccharides provide the structural matrix, although metal ions, particularly divalent cations like calcium and cobalt, cross-link with the polysaccharides, thereby modulating the biofilm's rigidity and viscoelastic behavior.

A microtiter peg lid with ziggurat geometry for medium-throughput antibiotic testing and imaging of biofilms.

Bacteria biofilm responses to disinfectants and antibiotics are quantified and observed using multiple methods, though microscopy, particularly confocal laser scanning microscopy (CLSM) is preferred due to speed, a reduction in user error, and analysis. CLSM can resolve biological and spatial heterogeneity of biofilms in 3D with limited throughput. The microplate peg-lid-based assay, described in ASTM E2799-22, is a medium-throughput method for testing biofilms but does not permit imaging.

Heterogenous biofilm mass-transport model replicates periphery sequestration of antibiotics in PAO1 microcolonies.

A model for antibiotic accumulation in bacterial biofilm microcolonies utilizing heterogenous porosity and attachment site profiles replicated the periphery sequestration reported in prior experimental studies on biofilm cell clusters. These cell clusters are in vitro models of the chronic infections in cystic fibrosis patients which display recalcitrance to antibiotic treatments, leading to exacerbated morbidity and mortality. This resistance has been partially attributed to periphery sequestration, where antibiotics fail to penetrate biofilm cell clusters.

Heterogenous Biofilm Mass-Transport Model Replicates Periphery Sequestration of Antibiotics in PAO1 Microcolonies.

A spatiotemporal model for antibiotic accumulation in bacterial biofilm microcolonies which leverages heterogenous porosity and attachment site profiles replicated the periphery sequestration phenomena reported in prior experimental studies on biofilm cell clusters. These cell clusters are models of the chronic infections found in adult cystic fibrosis patients, which display resistance to antibiotic treatments, leading to exacerbated morbidity and mortality. This resistance has been partially attributed to periphery sequestration, where antibiotics are unable to penetrate biofilm cell clusters.

Surface Energy and Viscoelastic Characteristics of and Biofilm on Commercial Skin Constructs versus agar.

Biofilms are recalcitrant to both study and infectious disease treatment as it requires not only the study or management of single organism behavior, but also many dynamical interactions including but not limited to bacteria-bacteria, bacteria-host, bacteria-nutrients, and bacteria-material across multiple time scales. This study performs comparative and quantitative research of two materials used in biofilm research, TSA agar and skin epidermal, to reveal how adhesion effects viscoelastic properties of biofilms at long time scales. We show that the host surface stressors, such as wettability and surface energy, impact the biofilm's mechanical integrity and viscoelastic properties.

In situ continuous electrochemical quantification of bacterial adhesion to electrically polarized metallic surfaces under shear.

Biofouling creates significant human and economic losses through infections, corrosion, and drag losses on ships and in oil and food distribution pipelines. Organisms adhered to these surfaces contend with high shear rates and are actively transported to the surface. The metallic surfaces to which these organisms are adhered also conduct charge at various potentials, and the effects of surface charge on adhesion rates are little addressed in the literature.

Adapting Undergraduate Research to Remote Work to Increase Engagement.

Demand for undergraduate research experiences typically outstrips the available laboratory positions, which could have been exacerbated during the remote work conditions imposed by the SARS-CoV-2/COVID-19 pandemic. This report presents a collection of examples of how undergraduates have been engaged in research under pandemic work restrictions. Examples include a range of projects related to fluid dynamics, cancer biology, nanomedicine, circadian clocks, metabolic disease, catalysis, and environmental remediation.

Continuous shear stress alters metabolism, mass-transport, and growth in electroactive biofilms independent of surface substrate transport.

Electroactive bacteria such as Geobacter sulfurreducens and Shewanella onedensis produce electrical current during their respiration; this has been exploited in bioelectrochemical systems. These bacteria form thicker biofilms and stay more active than soluble-respiring bacteria biofilms because their electron acceptor is always accessible. In bioelectrochemical systems such as microbial fuel cells, corrosion-resistant metals uptake current from the bacteria, producing power.

Microfluidic dielectrophoresis illuminates the relationship between microbial cell envelope polarizability and electrochemical activity.

Electrons can be transported from microbes to external insoluble electron acceptors (e.g., metal oxides or electrodes in an electrochemical cell).

A Status Report on FDA Approval of Medical Devices Containing Nanostructured Materials.

Commercialization has been slow since the FDA approved a medical device containing nanomaterials in 1980. In 2017, the FDA released draft guidance to accelerate approval. We highlight here that geographical and structural separation of researchers, manufacturers, and clinical servicers may slow commercialization more than FDA approval.