Colloids and Surfaces B: Biointerfaces

The rising incidence of invasive fungal diseases emphasizes the need for novel therapeutic strategies, including membrane-targeting antifungal agents, which require representative lipid models for detailed molecular-level studies. In this work, we propose a consensus quinary fungal plasma membrane model based on lipidomic literature data, specifically PC:PE:PI:PA:PS phospholipid model with ratio of 44:29:13:8:6. Using a bottom-up approach, we characterized the biophysical properties of this system - with particular emphasis on mechanical parameters such as bending rigidity and area compressibility - by combining molecular dynamics simulations with experimental flicker-noise and ATR-FTIR spectroscopies. Furthermore, we investigated the effect of two key non-phospholipid components: ergosterol and triacylglycerols. Biophysical analysis revealed that DPPI and its specific interactions with DSPS induced the most substantial deviations in baseline membrane parameters, particularly area per lipid, membrane thickness, and area compressibility, while DSPS influenced bending rigidity change and DLiPA primarily affected lipid packing defects. In addition, ergosterol and TGs were found to influence all of the investigated parameters to different degree. Notably, the overall biophysical profile of the proposed FPMM closely mimicked that of natural vesicles derived from yeast lipid extracts, establishing this model may provide a reliable platform for studying fungal membrane biophysics and lipid-targeting interactions.

Nile Red is widely used for the detection of microplastics because its fluorescence emission is sensitive to local polarity and can distinguish hydrophobic plastics from hydrophilic ones. The fluorescence of the molecular rotor, 9-(dicyanovinyl)-julolidine (DCVJ) is less sensitive to polarity but more to viscosity. DCVJ is less widely used for microplastic analysis, although it has been used to detect polystyrene nanobeads. Here, we compared these dyes with standard samples from the Hawaii Pacific University Polymer Kit 1.0 and confirmed that Nile Red, in general, was better for the detection and identification of microplastics. Fluorescence emission was analyzed using photography, as well as spectroscopy. The color and peak emission wavelength of some stained environmental microplastics were affected by additives. Raman spectroscopy was used to confirm the chemical identity of such samples. Although DCVJ emits green fluorescence on binding to some microplastics, a peak at 620 nm has been reported with polystyrene nanobeads, attributed to dimer/excimer formation. We confirmed this property and directly observed diffraction-limited spots using fluorescence microscopy, attributed to single or just a few nanobeads. Nile Red also stains polystyrene nanobeads and gave stronger signals than with DCVJ, but Nile Red was prone to false positives due to dye aggregation in aqueous solutions.

1.Surface functionality and pH play a decisive role in governing the structural dynamics, hydration, and drug-binding behaviour of dendrimers. Here, all-atom molecular dynamics (MD) simulations were performed on five generations of PAMAM (G1-G5) and PETIM (G2-G6) dendrimers with O-core and N-core architectures, functionalized with amine, carboxylic acid, or sugar terminal groups under different protonation states. Protonation of the tertiary branch-point amines expands the dendrimer structure, increases internal porosity and hydration, and enhances structural fluctuations across both families. In contrast, non-protonated amine -NH2 (NP) and carboxylic acid -COOH (NP) terminated dendrimers, together with deprotonated carboxylate-COO- (DeP) systems, retain comparatively compact conformations. Sugar-functionalized dendrimers ({beta}-galactose-terminated PETIM and D-glucose-terminated PAMAM) are most hydrated and structurally rigid, whereas amine-terminated dendrimers exhibit the greatest conformational dynamics. PAMAM dendrimers with -NH2, -NH3+, and -COO- terminal groups are generally more hydrated than their PETIM counterparts. However, {beta}-galactose-terminated PETIM dendrimers are more hydrophilic than D-glucose-terminated PAMAM dendrimers. N-core PETIM dendrimers also adopt more compact and spherical conformations than equivalent O-core PETIM dendrimers. Drug-binding MD simulations show that curcumin binding is dominated by van der Waals (vdW) interactions, whereas doxorubicin complexation is primarily driven by electrostatic interactions. Among the investigated surface functionalities, -NH2 (NP), -NH3+ (P), -COOH (NP), and -COO- (DeP) terminations exhibit the most favourable drug-binding characteristics. Except for deprotonated carboxylate systems, curcumin binds more strongly than doxorubicin. Overall, these findings establish molecular-level relationships between surface functionality, protonation state, dendrimer architecture, and drug-binding behaviour, providing design principles for pH-responsive dendrimer nanocarriers with enhanced drug-loading and controlled-release performance. TOC O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=75 SRC="FIGDIR/small/742721v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@119bf29org.highwire.dtl.DTLVardef@1554d86org.highwire.dtl.DTLVardef@154a254org.highwire.dtl.DTLVardef@16d5c5b_HPS_FORMAT_FIGEXP M_FIG C_FIG

Green synthesis of zinc oxide nanoparticles (ZnO NPs) offers a sustainable strategy for developing multifunctional antimicrobial nanomaterials. In this study, ZnO NPs were synthesized using Azadirachta indica leaf extract and characterized by UV-vis spectroscopy, FTIR, XRD, SEM, and GC-MS. The nanoparticles exhibited a characteristic absorption peak at 352 nm, a direct band gap of 3.07 eV, and hexagonal wurtzite crystallinity with an average crystallite size of approximately 32 nm. The biosynthesized ZnO NPs showed concentration-dependent antibacterial activity against Erwinia carotovora, producing inhibition zones of up to 25.9 mm. Mechanistic studies revealed significant membrane damage, evidenced by 4.77-fold and 5.62-fold increases in extracellular protein and amino acid leakage, respectively, with marked alterations in bacterial protein profiles detected by SDS-PAGE. The nanoparticles also exhibited strong antioxidant activity, achieving 89.4% DPPH radical scavenging, and induced dose-dependent cytotoxicity in HepG2 cells with an estimated IC50 of 124.8 g/mL. These findings demonstrate that neem-mediated ZnO nanoparticles possess potent antibacterial activity through membrane disruption while exhibiting promising antioxidant properties, highlighting their potential as eco-friendly nanomaterials for the management of bacterial soft rot and other phytopathogenic diseases.

Nisin is a promising antimicrobial peptide widely used in food preservation due to its efficacy against Gram-positive spoilage and pathogenic bacteria. Although Nisin is increasingly applied in the food sector, the biopeptide suffers from instability within food matrixes and can rapidly lose its antimicrobial potential following interaction with food biomolecules. Thus, it is necessary to investigate approaches that can be employed to extend the stability and activity of Nisin. Hence, the aim of this study was to develop and characterise a chitosan-alginate polyelectrolyte microencapsulation system capable of enhancing Nisin stability while retaining antimicrobial activity. The microencapsulation of Nisin was achieved by pre-gelation of alginate using calcium chloride and subsequent direct electrostatic interaction between cationic Nisin and chitosan with pre-gelled anionic alginate at pH 5.0. Following microcapsule formation, physicochemical and structural characterisation was performed using Zeta potential determination and measurement of the polydispersity index (PDI) via dynamic light scattering. SEM micrographs were used to confirm morphology, while Fourier-transform infrared (FTIR) spectroscopy and high-performance liquid chromatography (HPLC) were utilised to assess chemical integrity and functional group preservation of encapsulated Nisin. Following this, stable microcapsules with diameters ranging from 150-200 nm and smooth surface morphology were obtained. Microcapsule formation was strongly influenced by formulation parameters, particularly pH, calcium ion concentration, and chitosan content, with deviations from optimal acidic conditions (< pH 5.0) resulting in aggregation, increased polydispersity, and reduced encapsulation efficiency. The microcapsules were monodispersed (PDI {approx} 0.30) and electrostatically stable, exhibiting a Zeta potential of approximately +36 mV. These microcapsules remained stable over a prolonged storage period of 21 days under refrigerated conditions while retaining antimicrobial activity against Bacillus cereus. Encapsulation efficiency reached approximately 65%, confirming effective retention of Nisin within the polymer matrix. Overall, the findings demonstrate that chitosan-alginate ionic gelation is a non-denaturing and effective encapsulation strategy for extending the functional stability of Nisin. These microcapsules show strong potential as natural antimicrobial delivery systems for food and beverage applications, particularly in acidic food matrices, with implications for improved food safety and shelf-life extension.

Understanding the physicochemical factors that govern siRNA nanocarrier assembly is essential for the rational design of effective delivery systems. By optimizing various lipid compositions, cholesterol content and PEG length we created a peptide-functionalized cationic liposomal platform made of DOPE/TAP lipids with cholesterol-anchored nona-arginine (R9-Chol) for siRNA complexation, intracellular transport and effective silencing of the target EGFR gene. Analysis of {zeta}-potential and dynamic light scattering allowed to rationally design formulation of stable, monodisperse nanoscale lipoplexes with a positive surface charge. With fluorescence polarization, circular dichroism and agarose gel electrophoresis we found an optimal siRNA:liposome complexation ratio of 1:77, which protected siRNA from ribonuclease-mediated degradation. Morphological imaging confirmed a shift from discrete vesicular structures to organized multilamellar lipoplexes, consistent with electrostatically driven self-assembly. In cellular studies, the optimized nanocarrier promoted efficient uptake of fluorescent siRNA in MDA-MB-231 cells and achieved functional delivery of anti-EGFR, leading to substantially reduced expression of the target gene at both transcript and protein levels. This work offers mechanistic understanding of peptide-assisted lipid:siRNA assembly and positions R9-functionalized DOPE/TAP liposomes as a promising platform for siRNA delivery.

The effect of microcurrents on facultative microbial pathogens remains controversial. Solid cultures in Sabouraud Glucose Agar of the ubiquitous mold Aspergillus fumigatus were repeatedly treated with a commercially available device performing wireless conductive microelectrostimulation by 3.5 A microcurrent routed by spraying negatively charged air particles onto solid cultures in modified petri dishes. The treated cultures displayed increased growth compared to standard ones, but only as a function of mycelial density and total surface; the radial growth rate of the mycelium remained unaltered. The increased growth was positively related to the duration of the treatment. At the same time, secondary development (new mycelial loci within the dish) was greatly upheld due to treatment, as the spraying created microairstreams dislocating the fungal spores. These results imply perplexed kinetics of mycelial growth both with and without treatment, since the folding of the mycelial mat is observed regularly. Both the fungus response to the ES and the possible revision of growth kinetics create prospects for biotechnological and bioremediation applications but also imply biomedical considerations, regarding infection dynamics of mycelial fungi and their in situ resistance to immune responses and treatment.

Monitoring pH and extracellular acidification rate (ECA) in biological samples containing live mammalian cells can provide valuable information on the glycolytic activity and bioenergetic status of cells. Compared to pH electrodes, optochemical pH sensors look more advantageous, since they allow rapid, non-invasive parallel analysis of multiple samples with stable readout of pH. We have developed new fluorescent pH sensors based on hydrophobic protonable metal-free porphyrins,OEP and OEPK, embedded in a plasticized PVC matrix containing a proton transfer agent. These pH sensors provide internally-referenced calibration-free operation, both in ratiometric intensity and lifetime-based detection modes. Sensor development included optimization of the indicator dye and its photophysical characteristics, screening of different proton transfer agents to minimize sensor toxicity, tuning of the protonation range and pKa, long-term storage stability and response time studies. Optimised pH sensor coatings were then deposited on plastic substrates (96-well microplates) and used for real-time monitoring of Extracellular Acidification Rate (ECAR) for cultured cancer cells and 3D spheroid structures on standard laboratory equipment (multi-label plate reader and confocal FLIM microscope). The advanced pH sensors tailored for use with biological samples have high potential for cell analysis and related applications.

Graphene oxide (GO) has primarily been investigated as a carrier for intracellular delivery of therapeutic molecules. In previous work, we identified a cell type-dependent interaction pattern in which GO remained predominantly associated with the plasma membrane of cancer cells but was internalised by non-cancerous epithelial cells. Here, we explored whether plasma membrane-associated GO can be used as a platform to present bioactive ligands and influence cell-surface receptor signalling in cancer cells. To test this hypothesis, we targeted integrin receptors at the plasma membrane in glioblastoma cell models using an RGD-containing peptide non-covalently complexed with GO. We assessed GO-peptide interactions, cellular interactions/uptake, motility, and focal adhesion signalling readouts. Peptide association was quantified using a 2,4,6-trinitrobenzene sulfonic acid (TNBSA) assay, and GO was characterised by atomic force microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and colloidal measurements. Immediately after complexation, ~70% of RGD was associated with GO. Peptide association increased the nitrogen signal and shifted the principal GO XRD peak while retaining nanosheet morphology. Biological responses were examined in U87 and U251 glioblastoma cells with different integrin-positive fractions, and in non-cancerous BEAS-2B bronchial epithelial cells. Confocal microscopy showed that GO and GO:RGD remained predominantly localised on the plasma membrane in U87 and U251 cells, whereas greater intracellular localisation was observed in BEAS-2B cells. Importantly, GO:RGD significantly reduced key indicators of cell motility: cell velocity in U87 and U251 cells, with trajectory and mean-square-displacement analyses supporting restricted cellular movement. Free RGD had no significant effect, while GO alone produced a smaller reduction in motility only in U251 cells. No treatment significantly altered BEAS-2B motility. Flow cytometry also showed a reduced pFAK-associated signal in GO:RGD-treated U87 cells. These findings establish a proof of concept that the cell-line-dependent plasma membrane localisation of GO can be exploited as a membrane-associated nano-bio interface for cell-surface-active ligands, opening the way for the development of GO-based platforms that modulate receptor-mediated signalling and cell behaviour.

Antimicrobial resistance motivates the development of approaches capable of probing nanoparticle-bacterium interactions with nanoscale sensitivity. Here, synchrotron infrared nano-spectroscopy (SINS) is applied to investigate interactions between carbohydrate-coated silica nanoparticles and the Gram-negative model bacterium Escherichia coli at the single-cell level. Silica nanoparticles (SiO2) were coated with mannose, maltose, or trehalose to evaluate how surface carbohydrate chemistry influences their interactions with the bacterial envelope. Correlative electron microscopy revealed pronounced association of carbohydrate-SiO2 with the bacterial envelope, with features consistent with localization within the periplasmic region, whereas bare-SiO2 showed no detectable association. SINS measurements acquired directly on bacterial cells and at bacterium-nanoparticle interfaces revealed distinct, carbohydrate-dependent spectral signatures. Quantitative analysis of the amide I band used the I/I{beta} ; ratio, which describes the relative contributions of -helical and {beta}-sheet protein secondary-structure components, together with interface-dependent band-position analysis to characterize local spectral perturbations. Carbohydrate-SiO2 produced systematic changes in the I/I{beta} ; ratio, including at locations where nanoparticles were not directly observed, indicating that their effects extend beyond the sites of nanoparticle association. Comparison of measurements acquired on bacterial surfaces and at bacterium-nanoparticle interfaces further revealed that carbohydrate chemistry modulates both the magnitude and spatial extent of these spectral perturbations. Trehalose-SiO2 produced the largest interface-dependent amide I band shifts and a spectral component consistent with random-coil structures. Overall, these results demonstrate that carbohydrate surface chemistry modulates nanoscale protein conformational perturbations at the nano-bio interface and highlight SINS as a powerful approach for resolving chemically localized molecular responses at single-cell interfaces.

Bacterial melanin are macromolecules found in nature that provide a wide range of biological functions, including pigmentation, resistance to radiation, scavenging of free radicals, thermoregulation and protected from oxidative stress and harmful heavy metals. The melanin is crucial for pathogenesis and bacterial survival in a variety of circumstances, and they can also influence how bacteria interact with other organisms. Usually, bacteria produce the melanin is either black or brown colour. The produced melanin has excellent properties like antimicrobial, antioxidant, photoprotective and antibiofilm. This is a report on Corynebacterium amycolatum melanin-producing bacteria isolated from the marine sediment of Thiruvanmiyur beach in Tamil Nadu, India. Corynebacterium amycolatum was screened using tyrosine basal broth (TBB), and UV-visible spectroscopy, FTIR, and SEM were used to analyse the extracted melanin. The non-pathogenic nature of the Cornynebacterium amycolatum strain was verified through antibiotic sensitivity profiling. The cosmetic potential was evaluated using antioxidant and SPF assays. Corynebacterium amycolatum predominantly uses the DOPA pathway for melanin production, was confirmed using kojic acid inhibitor study. The in vitro studies on mouse fibroblast cell line (L929) and in vivo studies on zebra fish embryos shows non-cytotoxicity using this melanin, even in lower concentration confirms its potential to use in cosmetic formulation. This research aims to demonstrate that bacterial melanin is safe for the environment and has qualities that make it safer and more effective in cosmetics.

Chronic wounds (principally pressure sores, venous leg ulcers and diabetic foot ulcers) are a drain on global health services and remain a major area of unmet clinical need. Chronic wounds are characterised by a bacterial biofilm (densely aggregated colonies of bacteria encased by a matrix of extracellular polymeric substances), which hinders innate immune response and can prevent wound healing. Bioactive glass (BG) fibres doped with antimicrobial metal ions, such as silver, can offer a promising treatment for chronic wound infections, where silver is well known for its antimicrobial activity against a range of pathogens and is commonly used in wound dressings. We first present a system of non-linear partial differential equations to model the treatment of a chronic wound biofilm infection with BG fibres. The BG fibres are assumed to have two mechanisms of action against the biofilm: physical disruption of the top layers of the biofilm by the BG fibres; and release of antimicrobial silver ions from the BG fibres, which then diffuse into the biofilm and can kill the bacteria. Treatment-associated parameters are estimated from in vitro experimental data using a combination of least-squares minimisation and Approximate Bayesian Computation (ABC). Sensitivity investigations are performed on other parameters that cannot currently be calculated experimentally to investigate their influence on treatment efficacy. We thus predict key parameter regimes that should lead to biofilm eradication, crucially informing the future design of metal-doped BG fibres to maximise treatment efficacy. Author summaryChronic wounds are a huge drain on global health services and will become even more problematic due to an ageing population. Current treatment methods are often unsuccessful, where treatment failure is exacerbated by the presence of a biofilm infection. Biofilms consist of communities of bacteria that adhere to the wound surface and produce extracellular polymeric substances, which can protect the bacteria by acting as both a physical and chemical barrier. More recently, there has been a focus on biofilm-based wound care, where the aim is to firstly eradicate the biofilm infection, which then enables wound healing to occur naturally. Our aim is to produce a novel treatment that can target and eradicate the biofilm infection, followed by directly assisting the wound healing. Bioactive glass (BG) fibres doped with silver offer a promising treatment as they have both anti-biofilm effects and can also stimulate the wound healing process. Here, we restrict attention to their anti-biofilm properties. By developing a mathematical model, we can predict treatment outcomes under several different scenarios, the results of which can then be utilised during design of the BG fibres. Using this combination of computational and experimental approaches, we reduce both the cost and time of optimising this promising treatment.

Edible plant derived extracellular vesicles (PDEVs) are emerging as biocompatible, orally deliverable nanocarriers with therapeutic potential; however, their phytometabolite cargo, gastrointestinal stability, and source specific biological functions remain poorly characterized. Here, PDEVs were isolated from four phytochemically distinct plant based foods (black carrot, ginger, garlic, and turmeric), selected for their diverse bioactivity, and characterized by transmission electron microscopy, nanoparticle tracking analysis, and zeta potential. Gastrointestinal stability was evaluated in simulated digestion model. Source specific phytometabolites were profiled by untargeted LC MS MS metabolomics. Functionally validated in ammonia stressed epithelial cells and steatotic hepatocytes. PDEVs exhibited characteristic cup shaped morphology with particle sizes ranging from 60 to 214 nm and zeta potentials of -6.0 to -49.0 mV. PDEVs retained colloidal stability, supporting their suitability for oral delivery. We identified 572 phytometabolites with distinct source specific signatures, including lignin and quercetin in carrot EVs, [6] gingerol and silymarin in ginger EVs, diosgenin in garlic EVs, and curcumin in turmeric EVs. These metabolites found associated to antioxidant, anti inflammatory, epithelial barrier, lipid metabolic, and apoptotic pathways. Functional validation demonstrated carrot EVs significantly enhanced epithelial barrier integrity by increasing claudin (>8-fold, p<0.05), occludin (>2-fold, p<0.05). Ginger EVs restored ZO 1 while suppressing cyclin D1 and MMP9(p<0.05). Garlic and turmeric EVs attenuated inflammatory signaling by reducing STAT3, AKT1, and TNF , whereas turmeric EVs additionally decreased caspase 3 and PTGS2(p<0.01). In steatotic hepatocytes, garlic EVs significantly reduced PNPLA3 (p<0.001) and SREBP 1c while increasing PPAR- (p=0.002). Hence, our results indicate that edible PDEVs are gastrointestinally stable, phytometabolite enriched nanocarriers with distinct source specific functional properties, supporting their potential as orally deliverable nutraceuticals for improving gut liver functions.

Antibodies generally exhibit high specificity for their cognate epitopes, but structural and physicochemical similarities between distinct epitopes can enable an antibody to recognize different antigens, resulting in cross-reactivity. This property can be exploited for antibody repurposing. To identify epitopes that share such similarities, both sequence- and structure-based approaches can be employed. In this context, 3D Zernike descriptors provide a compact representation of protein surface geometry as numerical feature vectors, enabling quantitative comparisons independently of structural alignment and orientation. Thus, this study aimed to evaluate the application of 3D Zernike descriptors for the structural clustering of antibodies and epitopes and to explore their use in antibody repurposing for the recognition of new targets. To this end, antibody binding sites previously associated with recognition of similar epitopes were analyzed at different structural levels, considering the CDRs, CDRH3, and complete paratopes. Surface similarity was subsequently quantified by calculating the Euclidean distance between their corresponding 3D Zernike feature vectors. Performance was benchmarked against SPACE2. Additionally, different distance thresholds were evaluated based on their ability to recover antibody pairs recognizing the same epitope. The paratope-based approach provided the best balance between the number of identified pairs and precision at a distance threshold of 2.7, whereas epitope clustering showed robust performance up to a distance of 3.0. At these thresholds, the 3D Zernike descriptors identified a greater number of functional pairs than SPACE2 while maintaining comparable precision and identifying complementary sets of antibody pairs.. BTaken together, these findings support the use of 3D Zernike descriptors for structural clustering of antibodies and epitopes and for guiding antibody repurposing G, a highly lethal zoonotic pathogen. Structural screening identified three antibodies with epitopes similar to the NiV target that also showed a consistent binding preference for the target epitope in molecular docking assays. Notably, one candidate, originally directed against a SARS-CoV-2 epitope, formed a stable complex with the NiV epitope, remaining within the 5 [A] RMSD threshold during heated molecular dynamics simulations and emerging as a potential cross-reactive candidate.These results support the use of this computational framework for biopharmaceutical discovery against emerging targets. Taken together, these findings support the use of 3D Zernike descriptors for structural clustering of antibodies and epitopes and for guiding antibody repurposing.

Cardiolipin (CL) is a phospholipid found in the inner mitochondrial membrane (IMM) where it increases the efficiency of ATP regeneration. We have investigated the hypothesis that this increase may result in part from CL concentrating H+ at the IMM surface through electrostatic interactions as the CL polar head is a dianion at physiological pH. To this aim, we compared the concentrations and movements of H+ at the surface of giant planar phosphatidylcholine (PC) membranes and 20% CL enriched PC membranes by recording their surface pH with the membrane-grafted pH probe fluorescein DHPE. CL enrichment of the membranes increased their surface H+ activity by a ~4 factor. Moreover, we observed non-gaussian spatial H+ concentration profiles with distance from a point H+ source with both PC and CL membranes suggesting that both lipids also induce interactions between probe molecules. A whole bath pH variation revealed that these interactions allow the traveling of reversible acidification fronts with constant speed over the membrane between high and low pH states. A reaction-diffusion model of these observations suggests that membranes support these fronts through a mechanism of autocatalytic (de)protonation of the membrane surface. In mitochondria, these fronts would result in transitions between high and low pH states, the low one having a larger H+ concentration in CL-enriched regions of the IMM. Such an increase at the inner leaflet of the IMM may increase efficiency of the respiratory chain whereas the increase at the outer leaflet may boost the ATP synthase rate.

Three-dimensional (3D) spheroid culture provides a physiologically relevant alternative to conventional two-dimensional culture, but reliable spheroid formation in microwells depends on limiting cell-substrate adhesion. Pluronic F127 is an amphiphilic triblock copolymer that forms a hydrated surface layer, reducing protein adsorption. Here, we evaluated whether this intrinsic anti-fouling property could restore an anti-adhesive surface in used microwell plates to promote spheroid formation. Using chondrogenic ATDC5 and pancreatic {beta}-cell INS-1 cells, we characterized spheroid assembly kinetics, F127 cytotoxicity, surface hydrophilicity, protein adsorption, and spheroid morphology including size and shape factor. Both cell types formed compact spheroids within 24 hours on commercial anti-adhesive microwells. F127 coating markedly reduced water contact angle and protein adsorption, confirming increased surface hydrophilicity and reduced protein fouling. In microwells stripped of their original surface coating, F127 coating amounts of approximately 0.011-0.045 mg/cm2 consistently promoted spheroid formation across both cell types. Soluble F127 concentrations were confirmed to be non-cytotoxic up to 0.625% (w/v), while even complete dissolution of the highest tested coating amount would correspond to only 0.025% (w/v) F127. This simple, reproducible, and low-cost surface-modification strategy may provide an accessible approach for re-functionalizing microwell platforms for 3D cell culture.

Background: Natural compounds from avocado fruit (avocadene, avocadyne, and acetate derivatives) exhibit notable biological activity, although their molecular mechanisms remain unclear. The avocado-derived lipids exert potent nematocidal activity against several parasitic nematodes. In Caenorhabditis elegans (C. elegans), those compounds caused concentration-dependent toxicity, impairing first stage larval growth, egg hatching, and adult survival. Treated worms exhibited impaired mitochondrial respiration, reduced oxygen consumption, and elevated reactive oxygen species. These effects suggest that avocado lipids disrupt mitochondrial function and lipid metabolism, in part by inhibiting acetyl-CoA carboxylase, the rate-limiting enzyme of fatty acid biosynthesis. Methods: We investigated the effects of these compounds on the lipid profile of C. elegans and their association with endogenous lipid pools using NMR spectroscopy, click-chemistry-based fluorescence labeling, thin-layer chromatography (TLC), and microscopy. Results: Lipidomic analysis of stage 4 larvae (L4) and embryos treated with avocadene acetate revealed increased lipid NMR signals. Fluorescence-assisted TLC and NMR further suggested that avocadyne preferentially associates with triglyceride-linked fatty acids, particularly monounsaturated and flexible polyunsaturated chains, without detectable interactions with conformationally-constrained polyunsaturated species. Fluorescent avocadyne derivatives were efficiently internalized with distinct localization patterns in L4 larvae and embryonic cells. Conclusions: Overall, the lipid homeostasis remodeling of L4 larvae in response to lipotoxic shock was associated with phospholipid increase and remarkable lipid droplets onset, whereas embryos showed accumulation of lipids in enlarged droplets and developmental arrest.

Salmonella is a pathogen linked to foodborne outbreaks, including low-moisture foods. Its ability to resist desiccation can contribute to the formation of dry surface biofilms (DSB). This study evaluated the impact of 3 DSB formation protocols (P1=48-h hydrated phase/48-h dry phase, P2=24-h/120-h and P3=8-h/48-h) on the resistance of Salmonella DSB to 70% alcohol, a commercial product (based on 0.015% quaternary ammonium and 25% isopropyl alcohol), gaseous ozone (45 ppm), hot air (90 {degrees}C) and UV-C light (254 nm). The type of DSB protocol impacted the efficacy of the sanitizers (p < 0.05). The biofilm with the shortest hydration phase showed the greatest susceptibility; three out of the five sanitizers evaluated (70% alcohol, commercial product, and UV-C) promoted significant reductions in P3, with counts below the detection limit (0.8 log CFU/cm{superscript 2}) after 5 to 15 min exposure. Regarding protocols P1 and P2, in general, the best performance was from UV-C, especially against DSB on polypropylene, where it achieved reductions of 1.3 log CFU/cm{superscript 2} for P1 and 2.9 log CFU/cm{superscript 2} for P2 after 15 to 30 min of exposure. In contrast, hot air and ozone showed less effectiveness, with reductions [&le;]1.2 log CFU/cm{superscript 2}. In most scenarios, confocal microscopy images corroborated the plate count results (log CFU/cm{superscript 2}). In summary, our data indicates limited action of dry sanitizers on Salmonella DSB, requiring validation and optimization of sanitization processes to ensure the microbiological safety of low-moisture products.

Nanodiscs and bicelles are widely used as membrane mimetics for structural studies of membrane-associated systems. Studies have reported that their magnetic alignment behavior and phase stability are highly sensitive to composition and temperature. In this study, we systematically investigate the effects of cholesterol on bicelle formation and magnetic alignment in DMPC + 0.2 glycyrrhizic acid (GA) systems using a combined 31P and 14N solid-state NMR experimental and simulation-based approach. Temperature dependent 31P NMR spectra reveal a clear transition from vesicle dominant to aligned bicelles/nanodsics phase, while 1N quadrupolar splitting and lineshape analysis provides quantitative insights into heterogeneous lipid bilayer populations, distinguishing large aligned nanodiscs (B(L)), small nanodiscs (B(S)), and isotropic/random components (B(R)). A strong correlation is observed between the 31P derived bicelle fraction and the 14N B(L) population, confirming that macroscopic alignment in the presence of an external magnetic field directly reflects the growth of large, well-ordered nanodiscs. Cholesterol is found to play a critical dual role by modulating membrane order and curvature. At low cholesterol concentration (0 to 5 mole percent), nanodiscs alignment occurs gradually with increasing temperature, while at higher cholesterol concentration (15 to 25 mole percent), the alignment is delayed and accompanied by broader spectral features, indicating structural heterogeneity. Notably, 10 mole percent cholesterol consistently provides the optimal balance, enabling efficient temperature dependent conversion to aligned bicelles while maintaining high B(L) populations (about 70-80 percentage) and minimal isotropic fractions. In contrast, higher cholesterol maintains significant B(S) and B(R) populations, even at elevated temperature. The 14N quadrupolar coupling (Cq is approximately 8.5 to 9.2 kHz for aligned nanodiscs) remains nearly invariant across compositions, showing that cholesterol does not change local headgroup dynamics but instead redistributes lipid populations. These findings establish a combined 31P and 14N solid -state NMR approach provides a valuable platform for quantitatively correlating membrane structure, dynamics, and alignment, offering practical guidelines for optimizing bicelle systems for high resolution solid-state NMR studies of membrane associated biomolecules.

Fingertip friction plays a central role in tactile exploration and object manipulation. During sliding, tangential force depends jointly on the real contact area and the interfacial shear stress, both of which can be influenced by sliding conditions. However, changes in fingertip friction are often interpreted primarily through changes in real contact area, whereas the accompanying changes in interfacial shear stress remain less well characterized. This gap is especially relevant for electrostatic surface haptic displays, which modulate fingertip friction by applying a voltage between the finger and the touch surface. Here, we experimentally quantify the mean interfacial shear stress of a sliding fingertip on an electrostatically actuated touchscreen using simultaneous measurements of tangential force and optically resolved real contact area. Ten participants performed sliding trials across three speeds and three normal forces with and without electrostatic actuation. Interfacial shear stress increased with speed and decreased with normal force; in both cases, these trends arose because real contact area varied more strongly than tangential force. Electrostatic actuation further reduced interfacial shear stress, as increasing voltage produced a larger increase in real contact area than in tangential force. These findings show that interfacial shear stress varies systematically with sliding conditions and electrostatic actuation, clarifying how changes in real contact area and interfacial shear stress combine to shape fingertip-surface friction.