Journal of Colloid and Interface Science

Efficient drug delivery using nanoparticles (NPs) critically depends on their ability to diffuse through biological tissues to reach target cells at therapeutic concentrations. The extracellular matrix (ECM) poses a key barrier to such transport, which directly influences bio-distribution, cellular uptake, and overall therapeutic efficacy. A key regulator of this transport is hyaluronic acid/hyaluronan (HA), a major ECM polysaccharide that forms a hydrated, viscoelastic network. Increased/reduced hyaluronan concentration can elevate/decrease ECM bulk and effective viscosity. Increase in effective viscosity at the nanometer/micrometer length scales can hinder NP mobility through steric obstruction and hydrodynamic drag. There is a large variability in the HA molecular weights and concentrations, especially across age, tissue/organ, and pathological conditions. This work aims to study the diffusion of different NP types in the mixtures of HA polymers with variable molecular weights using the dynamic light scattering technique (DLS). Furthermore, we perform coarse-grained molecular dynamics (CG-MD) simulations for a model system to complement our findings from the dynamic light scattering experiments. We observe NP undergo anomalous diffusion, which is strongly dependent on the ratio of particle size/HA network mesh size, especially for higher molecular weight mixtures. This is strongly influenced by the effective viscosity, which is defined at the local environment experienced by the NPs. Our work highlights developing a simplified predictive framework coupled with simulations for a target-specific extracellular matrix environment.

Nanomaterials have been proposed as drug delivery vehicles to enhance targeting and efficiency of traditional and novel therapeutics and have subsequently been studied for potential ecotoxicity. Previous studies have identified size, surface charge, and volume exclusion as factors that influence nanomaterial diffusion and retention. However, there is little accepted or successful quantification of how these parameters influence nanomaterial penetration relative to biological adaptation and biological response. Part of the challenge is the response of living biological interfaces to many of these nanomaterial delivery vehicles and nanosized drugs. This study aimed to emulate key physicochemical barriers to diffusion found in living biomaterials by developing a tunable, synthetic hydrogel. Through the controlled exposure of 150 kDa and 2 MDa nanodextrans with neutral and negative surface charge, we evaluated the systems ability to emulate three core physicochemical features often implicated in biofilm-associated transport resistance: size exclusion, charge interactions, and volume exclusion. We demonstrated a 30% statistically significant decrease in partition coefficients for 2 MDa nanodextran from 150 kDa nanodextran, confirming the ability of the nanocellulose-based microcaps to mimic the permeability of hydrated biomaterial matrices. These findings reflect patterns observed in, for example, living biofilm studies, where size-based diffusion hinderance is commonly reported, but charge-based interaction and volume exclusion are more context-dependent. This controllable system can be coupled with in silico modeling to understand interfacial transport phenomena for nanomaterial-biomaterial interactions. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=91 SRC="FIGDIR/small/703274v1_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@13c1a34org.highwire.dtl.DTLVardef@dc6c5borg.highwire.dtl.DTLVardef@14dcbd4org.highwire.dtl.DTLVardef@80f70c_HPS_FORMAT_FIGEXP M_FIG C_FIG

Lipid nanoparticles (LNPs) are the most successful drug delivery carrier to date, but optimizing lipid formulations to improve membrane fusion capabilities for effective drug release has been challenging due to lack of a quantitative measure for fusogenicity. Here we introduce a new framework based on small angle X-ray scattering to experimentally measure [Formula] for lipids used in LNP formulations such as glycerol monooleate (GMO) and ionizable lipids (SM-102 and ALC-0315). Q intrinsically captures spontaneous curvature (J0), which is traditionally used to assess fusogenicity. The change of cubic lattice parameters with temperature was measured for GMO-containing lipid mixtures, and the Q extracted quantitatively correlated with LNP fusogenicity power validated by fluorescence-based fusion assays and cryogenic electron microscopy. Fusogenicity of SM-102 and ALC-0315 was quantified by adding them to host membranes and assessing change in Q. This framework provides researchers with the ability to optimize the fusogenicity of LNP formulations for potent drug release and enhances understanding of parameters governing fusion in all biomembranes.

Silver (Ag+) ions are known to be toxic to bacteria, cells, organisms and living systems; yet its impacts on the locomotion of surface-crawling organisms remain poorly quantified. Here we investigated the short-term (0-6 hours) effects of Ag+ ions on the locomotion of Drosophila melanogaster larvae on flat agarose surfaces containing Ag+ ions at different concentrations (0, 1, 10, and 100 mM). By quantifying their locomotion, we found that Drosophila larvae showed shorter accumulated distances and reduced crawling speed. Additionally, we quantified the go/stop dynamics and peristalsis of the larvae and observed that Ag+ ions disrupted the normal, rhythmic, peristaltic contraction of the larvae and "trapped" them in the stop phase. Such toxic effects were dependent on Ag+ concentration and exposure duration.

Microplastic (MP) pollution, which is present in the ecosystem in vast quantities, adversely affects human health and the environment, making it imperative to develop methods for its mitigation. The challenge of detecting or capturing MPs could potentially be addressed using plastic-binding peptides (PBPs). The ideal PBP for MP remediation would not only bind strongly to plastic, but also have other properties such as high solubility in water or great binding specificity to a certain plastic. However, the scarcity or absence of known PBPs for common plastics along with the lack of methods that can discover PBPs with all of the desired properties precludes the development of peptide-based MP remediation strategies. In this study, we discovered short linear PBPs with high predicted water solubility and binding specificity by employing an in-silico discovery pipeline that combines deep learning and biophysical modeling. First, a long short-term memory (LSTM) network was trained on biophysical modeling data to predict peptide affinity to plastic. High affinity peptides were generated by pairing the trained LSTM with a Monte Carlo tree search (MCTS) algorithm. Molecular dynamics (MD) simulations showed that the PBPs discovered for polyethylene, the most common plastic, had 15% lower binding free energy than PBPs obtained using biophysical modeling alone. PBPs with both high affinity and high predicted solubility in water were found by including the CamSol solubility score in the MCTS peptide scoring function, increasing the average solubility score from 0.2 to 0.9, while only minimally decreasing affinity for polyethylene. The framework also discovered peptides with high binding specificity between polystyrene and polyethylene, two major constituents of MP pollution, using a competitive MCTS approach that optimized the difference in affinity between the two plastics. MD simulations showed that competitive MCTS increased the binding specificity of PBPs for polystyrene and identified peptides with relatively great preference for either of the two plastics. The framework can readily be applied to design PBPs for other types of plastic. Overall, the high-affinity PBPs with desirable properties discovered by marrying artificial intelligence and biophysics can be valuable for remediating MP pollution and protecting the health of humans and the environment.

Coacervate droplets and lipid vesicles are two classes of self-assembled compartments that have been proposed as protocell models. Hybrid protocells, in which a coacervate core is surrounded by a lipid membrane, can integrate the advantages of both protocell systems while overcoming their limitations. Although hybrid protocell membranes have been produced with a variety of diacyl phospholipids related to modern biology and some single-chain amphiphiles inspired by prebiotic scenarios, little is known about how mixtures of single-chain amphiphiles impact hybrid protocell membrane formation and properties. Given the plausible diversity of amphiphiles in the prebiotic milieu, the resulting membranes would have inherently incorporated multiple lipids of different types, potentially altering the properties and viability of hybrid protocells in their environment. Here, we systematically increased the compositional heterogeneity of hybrid protocell membranes by using different prebiotically relevant single-chain amphiphiles of varying head groups and alkyl chain lengths. These membranes were assembled around model coacervate droplets generated from polyallylamine hydrochloride and adenosine diphosphate, and the effect of heterogeneity on membrane properties and stability was evaluated. Compared to protocells with homogeneous membranes, those with heterogeneous amphiphile membranes exhibited higher yields, smaller sizes, and greater sub-compartment formation. Also, they showed increased membrane order, retained similar lateral lipid diffusion, and showed population-level variability in permeability to small anionic molecules. Notably, heterogeneous membranes showed enhanced structural stability under acidic conditions, retaining key properties like size and sub-compartment heterogeneity, thereby broadening the pH range over which hybrid protocells remain intact. These findings suggest that amphiphile diversity not only would have influenced the structural properties of hybrid protocells but also created diversity within the protocell population and enhanced their robustness, thereby playing a crucial role in protocell evolution on early Earth.

The global rise of antimicrobial resistance has significantly reduced the effectiveness of conventional antibiotics, highlighting the urgent need for alternative and complementary therapeutic strategies. Nanotechnology-based drug delivery systems, particularly lipid nanoparticles, have emerged as promising tools to enhance antibiotic efficacy while limiting toxicity and resistance development. In this study, we evaluated the antimicrobial activity and drug carrier potential of Ohmline, a novel alkyl-ether glycolipid capable of self-assembling into nanotubes and lipid nanoparticles. First, a wide range of Gram-positive and Gram-negative bacteria were used to test Ohmline nanotubes antibacterial activity. All examined strains were partially inhibited, with a more noticeable effect on Gram-positive bacteria. Then, the synergistic potential of Ohmline combined with commercially available antibiotics (ampicillin, ceftriaxone, and ciprofloxacin) was evaluated using two different approaches: binary mixtures of Ohmline nanotubes and antibiotics and microfluidically produced Ohmline:DMPC (75:25) nanoparticles with the antibiotics encapsulated. Binary formulations demonstrated strong, strain-dependent synergistic effects at sub-MIC antibiotic concentrations, particularly against Enterococcus faecalis and Citrobacter braakii. Notably, antibiotic encapsulation within Ohmline nanoparticles further enhanced antimicrobial efficacy compared to non-encapsulated combinations, achieving near-complete growth inhibition in E. faecalis and significant inhibition in Klebsiella pneumoniae and C. braakii. Overall, our findings demonstrate that Ohmline possesses intrinsic antibacterial activity and acts as an effective lipid nanocarrier that potentiates antibiotic action. The dual functionality of Ohmline supports its potential as a versatile building block for next-generation antimicrobial formulations.

Cotton-based antimicrobial textiles are attractive for applications requiring improved microbiological control, but their performance depends on effective surface functionalization and retention of the active materials after use and washing. In this work, cotton fabrics were functionalized with hydroxyl-rich graphene oxide (HGO), hydroxyl-rich reduced graphene oxide (H-rGO), and silver nanowires (AgNWs), either individually or in combined treatments, to investigate their deposition onto the textile surface, washing resistance, and preliminary antibacterial activity. The treated fabrics were prepared by immersion-based coating procedures, and the persistence of the deposited materials after repeated washing was evaluated by UV-Vis analysis of the residual wash solutions. Surface morphology before and after washing was examined by scanning electron microscopy. The results showed that graphene-based coatings, particularly HGO, exhibited stronger retention on cotton fibers, while AgNWs were partially retained after repeated washing cycles. SEM images confirmed the deposition of AgNWs on the cotton surface and showed that part of the coating remained associated with the fibers after washing. A preliminary antibacterial assay against Escherichia coli indicated that nanomaterial-treated fabrics inhibited bacterial growth relative to untreated controls, with the combined HGO/AgNWs treatment showing the most promising inhibitory trend under the tested conditions. These findings demonstrate the feasibility of producing cotton fabrics functionalized with hydroxyl-rich graphene derivatives and silver nanowires, supporting their potential as proof-of-concept antibacterial textiles with partial washing resistance.

Nanoplastics generated from plastic waste in our ecosystems are becoming increasingly prevalent as bulk plastics exposed to natural factors like water and sunlight fragment to the nanoscale over time. These incidental nanoplastics span a wide range of physicochemical properties, which makes studying nanoplastic interactions in biological systems difficult. Here, we characterized the behavior of incidental nanoplastics generated through mechanical abrasion within coacervate droplets to probe the surface properties of the nanoplastics. We used elastin-like polypeptides (ELPs) to create hydrophobic or charged coacervate microenvironments. Using optical microscopy and fluorescence quantification, we observed that nanoplastics made from polyethylene terephthalate (nPET), nylon 6 (nPA), and polystyrene (nPS) exhibited distinct partitioning behavior with more favorable interactions with hydrophobic droplets. This indicated that the hydrophobic polymer backbone was the predominate surface feature despite exposed functional groups of the incidental nanoplastics, in contrast to findings with model carboxylated latex nanospheres (nPS-COOH). Furthermore, the selective partitioning of incidental nanoplastics into the hydrophobic droplets was able to capture over 80% of nPET in solution, and after recovery of the protein droplet, was able to cumulatively capture over 75% of the nPET feedstock across multiple cycles. This work explores the nuanced surface characteristics of incidental nanoplastics, expands the application of coacervates as chemical probes, and demonstrates a biopolymer approach for effective nanoplastic removal.

Escherichia coli (E. coli) biofilms consist of bacteria, an extracellular matrix (ECM) mainly made of curli amyloid fibers, phosphoethanolamine-modified cellulose (pEtN-cellulose), and water. While curli amyloid fibers contribute to biofilm rigidity, pEtN-cellulose contributes to their cohesion. This work explores the interplay between these fibers, and how their interaction influence biofilm structure and mechanical properties. We performed a multiscale analysis on E. coli biofilms grown using strains producing curli and pEtN-cellulose, and only curli and only pEtN-cellulose in co-seeded ratios. Micro-indentation experiments, confocal microscopy, and cryo-FIBSEM 3D imaging revealed a composite-like behavior of the biofilm, where its mechanical properties depend on ECM composition and organization. Spectroscopic analysis of the extracted fibers showed that their biophysical properties are influenced by their pEtN-cellulose to curli ratio and assembly. We propose that pEtN-cellulose swelling is contrained by its interactions with rigid curli fibers. The reference E. coli strain maximizes this effect by assembling a curli/pEtN-cellulose hybrid material at the sub-micron scale, where its composition, interactions, and architecture can explain biofilm emergent properties. This knowledge on microbial ECM assembly opens new avenues for engineering living materials, especially for the use of bacterial biofilms as a source of bio-sourced materials.

The apparent pKa of ionizable lipids in lipid nanoparticles (LNPs) is a key determinant of RNA encapsulation during formulation and endosomal release after cellular uptake. However, it is difficult to predict the effective pKa of a given ionizable lipid solely from its solution pKa, because it is sensitive to the membranes composition, as well as solution conditions such as the salt concentration. We developed a simple continuum electrostatics model, based on Gouy-Chapman theory, to predict the shift in effective pKa for ionizable lipids in lipid bilayers as a function of salt concentration and membrane composition. We derive equations for the surface potential and fraction of lipids charged, which are solved self-consistently as a function of solution pH to extract the titration curve and effective pKa. The model shows that the shift in effective pKa is largest when the concentration of titratable lipid is high, and the effect is diminished by increasing salt concentration. We provide a python implementation of the model and an interactive notebook that will allow users to further easily explore the predicted pKa shifts as a function of formulation variables.

The conformational dynamics of a model cationic protein in water and in the presence of anionic sodium dodecyl sulphate (SDS) and cationic cetyltrimethylamonium bromide (CTAB) surfactants at different concentrations were investigated using all-atom molecular dynamics simulations. Free-energy landscapes constructed along principal components reveal a compact, well-defined native basin at 25 {degrees}C in water, whereas elevated temperature (100 {degrees}C) induces a broadening of the conformational space and the emergence of multiple metastable states. The presence of surfactants further modulates this behavior in a concentration-dependent manner. Cluster population analysis shows that SDS promotes a highly heterogeneous ensemble characterized by reduced dominance of the native-like cluster, while CTAB partially protects the protein from thermal denaturation at higher concentrations. Radial distribution functions demonstrate strong accumulation of SDS headgroups around the protein and pronounced insertion of SDS alkyl tails into hydrophobic protein regions, indicating direct hydrophobic destabilization and micelle-assisted unfolding. In contrast, CTAB exhibits weaker headgroup association owing to electrostatic repulsion and reduced tail-hydrophobic contacts, suggesting a less disruptive interaction mechanism. At high concentration, CTAB aggregates provide a structured hydrophobic environment that stabilizes the folded state and suppresses denaturation. Together, these results provide a molecular-level picture of how surfactant chemistry and concentration govern the conformational stability of a cationic protein, highlighting the dominant role of hydrophobic interactions in surfactant-induced denaturation at high temperature. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=89 SRC="FIGDIR/small/717321v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@f68004org.highwire.dtl.DTLVardef@14e9a98org.highwire.dtl.DTLVardef@18771d3org.highwire.dtl.DTLVardef@141fc6f_HPS_FORMAT_FIGEXP M_FIG C_FIG

Polyethylene terephthalate (PET) is a commonly used plastic worldwide and reducing its prevalence is crucial to improving environmental pollution. PETase that degrades PET plastic have received a lot of attention recently. This paper evaluates the ester hydrolysis process under both acidic and basic conditions, and shows that the local environment of the protein active site takes advantage of both. High pH in the protein buffer creates a better nucleophile to attack the ester through a proton shuttle channel in the protein, while local hydrogen bonds to the carbonyl of the ester stabilizes the intermediate/transition state of the hydrolysis reaction. With the understanding at the atomic level, we propose two engineering directions that can potentially improve the reactivity of the PETase: 1) increase the alkaline stability of the protein in general; 2) perturb the local hydrogen bond network to increase the partial charge on the PET carbonyl to be hydrolyzed. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=139 SRC="FIGDIR/small/703441v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@151b69borg.highwire.dtl.DTLVardef@1abb95dorg.highwire.dtl.DTLVardef@116a225org.highwire.dtl.DTLVardef@ef2bb1_HPS_FORMAT_FIGEXP M_FIG C_FIG

Plastic materials are widely used in engineered systems and increasingly accumulate in natural environments, where their surfaces interact with colloids, microorganisms, and dissolved organic matter. However, the relative roles of plastic surface properties versus particle-specific characteristics in governing organic matter retention remain poorly constrained. Here, attachment efficiency () was used to quantify intrinsic particle-collector affinity on three common thermoplastics (ABS, HDPE, HIPS) and glass beads as an inorganic reference. Surface chemistry, hydrophobicity, roughness, and charge were characterized, and interactions with submicron carbon particles (SCPs) and Escherichia coli were evaluated using column experiments. Extended DLVO (XDLVO) theory was applied to predict interaction energy barriers, and humic acid (HA) adsorption was quantified through batch isotherms. XDLVO modeling predicted higher affinity of particles for plastics relative to glass; however, experimentally measured attachment efficiencies were uniformly low ( < 0.05) across all materials. Attachment was primarily governed by particle size and surface charge rather than collector hydrophobicity, roughness, or surface chemistry. SCP consistently exhibited higher than bacteria, while differences among plastics were minor. Similarly, HA adsorption was weak and near-linear, with uptake following ABS {approx} HIPS > HDPE > glass, indicating reversible, partitioning-like association dominated by polymer-specific functionality rather than electrostatics. The absence of correlation between and XDLVO-predicted energy barriers further demonstrates limitations of classical physicochemical models in describing particle- plastic interactions. Collectively, these results indicate that pristine thermoplastic surfaces exhibit intrinsically low affinity for organic matter and that particle-specific properties dominate retention under low ionic strength conditions. Enhanced accumulation in environmental systems likely requires surface aging or conditioning processes not captured by classical interaction theory.

Multidrug resistant (MDR) bacterial wound infections are an increasing clinical challenge and require alternatives to conventional antibiotics. Although antimicrobial proteins offer promise, their therapeutic use is limited by poor stability, proteolytic degradation, reduced activity under physiological conditions, and potential toxicity. This work reports pH-sensitive lipid nanocarriers composed of granulysin (GNLY) and oleic acid (OA) for antimicrobial delivery to infected tissues. At neutral pH, GNLY is retained within OA-based nanocarriers and protected from proteolytic degradation. At pH 5.0, such as in infected wounds, the carriers undergo structural reorganization and release GNLY, restoring antimicrobial activity. OAGNLY (32 {micro}g/mL) achieved >3-log reductions in Staphylococcus aureus and Escherichia coli within 1 hour, and up to 4-log reductions in Pseudomonas aeruginosa and Acinetobacter baumannii, at physiological salt concentrations where free GNLY was largely inactive. Minimum inhibitory concentrations were 16 {micro}g/mL for MRSA and 32 {micro}g/mL for colistin-resistant E. coli. Ultrastructural analysis using transmission electron microscopy revealed disruptions of bacterial membranes and intracellular structures following OAGNLY treatment. In a murine surgical wound infection model, topical application of OAGNLY for 4 hours reduced bacterial burden by >5 logs and significantly decreased inflammation, as confirmed by histological analysis. In parallel, OAGNLY demonstrated minimal cytotoxicity to mammalian cells at active concentrations. These findings identify OAGNLY nanocarriers as a promising platform for pH-responsive delivery of GNLY and highlight their potential application for treating MDR skin and soft tissue infections..

This study investigated the effects of different downstream processes for protein isolation on the bulk properties and composition of clover grass protein prototypes (CGPs). A clarified clover grass juice, obtained using membrane filtration (MF), underwent precipitation by acid (AP), heat (HP), or acid+heat (AHP), or underwent ultra- and diafiltration to produce a concentrate (DC) as well as subsequent tryptic hydrolysis of DC (DCH). HP had the highest protein content (p<0.05) and was whiter than other CGPs, although it showed lower aqueous solubility. In contrast, DC showed excellent solubility across a broad pH range. CGPs efficiently decreased oil-water interfacial tension (16-13 mN/m) and displayed viscoelastic and solid-like interfacial behavior. CGPs-stabilized emulsions displayed low physical stability with larger droplets despite high absolute {zeta}-potentials. CGPs were rich in RuBisCO (37-47%) but had varying levels of other proteins. Despite significant protein-level differences, overall protein composition of CGPs was comparable, highlighting that protein state governs bulk functionality more than subtle compositional changes. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=108 SRC="FIGDIR/small/701969v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@f37756org.highwire.dtl.DTLVardef@1fb5beorg.highwire.dtl.DTLVardef@1d4efe2org.highwire.dtl.DTLVardef@d11ef8_HPS_FORMAT_FIGEXP M_FIG C_FIG Created with BioRender.com HighlightsO_LIThe effect of different processes on functional properties of CGPs was explored. C_LIO_LIHeat treatment increased protein purity and whiteness at the expense of solubility. C_LIO_LICGPs efficiently reduced O/W interfacial tension but produced unstable emulsions. C_LIO_LICGPs were found rich in RuBisCO (34-47%) using quantitative proteomics. C_LIO_LIProtein state had larger influence on functionality than protein-level composition. C_LI

mRNA-lipid nanoparticles (LNP) have proven their potential as a rapidly adaptable vaccine platform and promise to revolutionize numerous therapeutic areas. A major hurdle towards the widespread adoption of mRNA-LNP vaccines and therapeutics is their limited liquid shelf-life compared to more established modalities currently necessitating an ultralow temperature cold-chain to enable their distribution and storage. While ongoing efforts aim to improve liquid stability through chemical modification of mRNA and lipid components, complementary strategies that are broadly applicable across chemistries may further accelerate translation. Here, we present an approach to improve the liquid shelf-life of mRNA-LNPs that does not rely on modifications to the mRNA or LNP chemistry. In particular, we show that bleb formation induced by high ionic strength acidic citrate buffers during LNP formation reduces mRNA degradation and retains in vitro activity during extended liquid storage. We observed an increase in the in vitro activity storage half-life from 2.8 to 18.9 days at 25{degrees}C when prepared using high ionic strength buffers translating into a [~]7-fold improvement in the liquid shelf-life of MC3-LNPs. This enhanced stability of LNPs with large amount of bleb formation was mainly attributed to reduced rates of lipid-mRNA adduct formation and mRNA fragmentation. Furthermore, the acidic buffer dependent stabilization was observed across different ionizable lipids with the extent dependent on the ionizable lipid head group. We envision that the induction of bleb formation via selection of appropriate acidic mixing buffers may represent a universal approach to enhance mRNA-LNPs stability and enable extended long-term refrigerated storage.

Saturated fatty acids such as stearic acid (SA) can exhibit both antimicrobial and growth-promoting effects on bacteria, depending on their concentration and chemical structure. However, the physical properties of the bacterial cell envelope in response to such molecules remain under-explored compared to their biochemical pathways. In this study, a comprehensive investigation is presented on the interaction of SA with the Gram-positive bacterium, Staphylococcus epider-midis (S. epi). SA alters bacterial growth, reflected in a higher maximum specific growth rate, a shorter lag phase, and an extended exponential phase, consistent with a prebiotic effect. Using fluorescence correlation spectroscopy and fluorescence lifetime imaging microscopy, we show that SA incorporation leads to significant fluidization of the lipid membrane, characterized by enhanced lateral diffusion and reduced membrane viscosity. Coarse-grained molecular dynamics (CG-MD) simulations demonstrate spontaneous insertion of SA into the membrane and a significant increase in mean-square displacement after insertion, supporting our experimental observations. Importantly, atomic force microscopy measurements show an increase in cell-envelope stiffness, reflected by a higher Youngs modulus which can be attributed to modulations in the glycan-peptide linkage density based on earlier studies that correlate stiffness changes to peptidoglycan (PG) crosslinking in Gram-positive strains [1]. These results provide direct evidence linking membrane fluidization induced by SA and increased cell wall stiffness due to transport modifications in the membrane mediated PG synthesis pathways to enhance bacterial cell viability.

The production of petroleum-based plastics used for packaging has led to significant environmental challenges in both aquatic and terrestrial ecosystems. Consequently, there is a growing need to explore viable alternatives to the usage of these conventional plastics. This study investigates the utilization of cellulose powder for producing of biodegradable plastics as a more sustainable substitute for petroleum-based materials. Bioplastic films were formulated with varying glycerol contents ranging from 0.5ml - 2.0ml. The glycerol served as a plasticizer to improve the mechanical properties of the films, which were subsequently subjected to biodegradability and tensile strength tests. Biodegradability was evaluated through soil burial tests, which revealed that higher glycerol concentrations accelerated rate of weight loss, with the 2.0 ml formulation exhibiting the fastest degradation rate. Tensile strength increased with glycerol content up to 1.5 ml, where a maximum strength of 7.23 N/mm2 was recorded, but declined at 2.0 ml. The findings indicate that a glycerol concentration of 1.5 ml yields the most optimal bioplastic formulation for short-term packaging applications.

Biofilms in the built environment (BE) can harbor pathogens and have been linked with negative health outcomes, particularly in hospital environments. The formation of biofilms requires bacterial cell attachment on surfaces, such as hospital plumbing, which can have varying properties, including roughness, wettability, chemistry, and charge. Despite the importance of bacterial attachment to surfaces, the role of multiple surface properties has been minimally investigated. Using seven materials with differing surface characteristics, this work considers the initial attachment of Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus to investigate the impact of several surface characteristics. Initial attachment was evaluated using column experiments and compared to batch experiments in which bacterial growth on coupons was monitored. The attachment of all bacterial species was not influenced by material surface properties, with similar attachment seen across materials tested. Bacterial cell envelope morphology affected attachment, with gram-negative species displaying greater attachment than gram-positive species. Attachment efficiency () was found to be a good predictor of bacterial attachment, with greater sensitivity than batch tests. Establishment of commensal communities should be the focus for limiting pathogens in the BE, as engineering surfaces to reduce microbial attachment appears to offer limited benefit.