Search Results (1,749)

Microbial biosurfactants (mBSs) are bioactive molecules with diverse applications, notably as antimicrobial agents against antibiotic-resistant pathogens. Produced by bacteria and yeasts, mBSs are classified as glycolipids, lipopeptides, polymeric, and particulate types. The global rise in multidrug-resistant organisms, such as Escherichia coli, Klebsiella pneumoniae, Salmonella typhimurium, Pseudomonas aeruginosa, and Acinetobacter baumannii, underscores the urgent need for new antimicrobial strategies. mBSs disrupt microbial growth by interacting with the lipid components of pathogens, offering promising alternatives to conventional antibiotics. This review highlights the sources, chemical structures, and properties of mBSs, their antimicrobial activities, synergistic effects with antibiotics, and structure–activity relationships. Special emphasis is placed on surfactant modification, where targeted changes—such as valine substitution in surfactin—significantly lower critical micelle concentrations (CMC) and enhance antimicrobial potency. Such rational engineering demonstrates how biosurfactants can be tailored for improved biomedical performance while minimizing cytotoxicity. In parallel, artificial intelligence (AI) algorithms, including artificial neural networks and genetic algorithms, optimize yields, predict substrate suitability from agricultural residues, and guide microbial strain engineering. AI models can predict interfacial behavior and synchronize fermentation with purification. Advancing the understanding of mBS interactions with microbial membranes, combined with modification strategies and AI-guided optimization, is essential for developing targeted therapies against resistant infections. Future research should integrate these approaches to engineer novel derivatives, reduce costs, and validate clinical potential through comprehensive in vivo studies. Full article

Wound dressing coverages (WDC) play a key role in protecting skin lesions and preventing infection. Polymeric membranes have been widely explored as WDC due to their ability to incorporate bioactive agents, including antimicrobial nanoparticles and non-steroidal anti-inflammatory drugs (NSAIDs). In this study, polycaprolactone (PCL)-based membranes functionalized with titanium dioxide nanoparticles (TiO₂ NPs) and ibuprofen (IBP) were fabricated using a film manufacturing approach, and their structural and biocompatibility profiles were evaluated. The membranes were characterized by SEM, FTIR and XPS. Bands at 1725 cm⁻¹, 2950 cm⁻¹, 2955 cm⁻¹, 2865 cm⁻¹ and 510 cm⁻¹ proved molecular stability of reagents during manufacture. In SEM, the control shows the flattest surface, while the PCL-IBP and PCL-IBP-TiO₂ NPs groups had increased rugosity. In vitro biocompatibility was evaluated using human fetal osteoblasts (hFOB). On day 3, the cell adhesion response of hFOB seeded in PCL-IBP and PCL-IBP-TiO₂ NPs groups showed the biggest absorbances (p = 0.0014 and p = 0.0491, respectively). On day 7 PCL-IBP group had lower lectin binding than the control (p = 0.007) and the PCL-IBP-TiO₂ NPs (p = 0.015) membranes, but no evidence of cytotoxicity was observed in any group. Furthermore, the Live/Dead test adds more biocompatibility evidence to conveniently discriminate between live and dead cells. The PCL polymeric membrane elaborated in this study may confer antiseptic, analgesic and anti-inflammatory properties, making these membranes ideal for skin lesions. Full article

Hydrophilic modification of polymeric membranes by employing TiO₂ nanoparticles has attracted much attention in enhancing antifouling performance. Micelles of PVPylated-TiO₂ nanoparticles were designed to alleviate the agglomeration of TiO₂ nanoparticles via steric hindrance and electrostatic stabilization effect. Herein, Poly(vinyl pyrrolidone) (PVP) was used as a surfactant to mitigate the thorny agglomeration of nanoparticles in the casting solution and simultaneously as a pore-forming additive during the membrane preparation process. The lowest backscattering (BS) peak and turbiscan stability index (TSI) of the composite casting solution indicated the effective dispersion and stabilization under the steric interaction of 4 wt.% PVP. Properties such as the fully developed finger-like structure of cross-sectional morphologies, water permeability, negative Zeta potential, and hydrophilicity were enhanced evidently by the optimal modification of PVPylated-TiO₂ materials. High interaction energy indicated by classic extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory as well as the high relative flux during the filtration of various model foulants demonstrated the effective antifouling modification. The results of critical flux and fouling rate in 30 min also verified the enhancement of the antifouling performance of PVDF/PVPylated-TiO₂ composite membrane. This work provides a feasible strategy to construct composite membranes with high antifouling performance for wastewater treatment. Full article

Waterproofing systems frequently experience performance degradation during long-term service due to material aging and structural deformation, thereby necessitating localized repair interventions. The bonding interface between newly applied and existing membrane materials is a critical determinant of repair effectiveness. In this study, the aging-dependent repair performance of three representative waterproof membrane systems was systematically investigated using peel strength testing, low-temperature flexibility assessment, and interfacial morphology analysis under thermal–oxidative aging for 2, 5, 14, and 28 days. The results demonstrate that the homogeneous repair system based on ultra-thin reinforced self-adhesive polymer-modified bituminous membranes exhibits superior overall performance, maintaining the highest peel strength with only minor degradation even after 28 days of accelerated aging. In contrast, the polymeric butyl self-adhesive membrane subjected to homogeneous repair exhibited rapid adhesion degradation after 14 days, whereas the heterogeneous repair system showed improved stability during intermediate aging stages. Low-temperature flexibility testing further revealed that root-resistant bituminous membranes exhibited a slower aging rate, with a cracking temperature increase of 7 °C after 28 days, compared to a 10 °C increase observed for ultra-thin self-adhesive membranes. These quantitative findings provide clear guidance for the selection of appropriate repair membrane systems under varying aging conditions in waterproofing engineering, particularly for maintenance and rehabilitation applications. Full article

Herein, we report the synthesis via controlled reversible addition-fragmentation chain transfer (RAFT) polymerization of amphiphilic 2-vinylpyridine-b-styrene (2VPy-b-Sty) diblock copolymers of high molar masses (range: 52,100–304,000 g mol⁻¹) and various compositions (range: 2VP content 11.6–59.2 mol%) and their use for the fabrication of nanoporous membranes. The successful synthesis of the amphiphilic diblock copolymers was confirmed through the characterization of their molar masses, molar mass distribution, and composition using GPC and ¹H-NMR spectroscopy, respectively. Subsequently, membranes of the diblock copolymers were fabricated following the “phase inversion” technique. The resulting membranes were characterized via scanning electron microscopy which revealed the presence of sphere percolation networks morphology for all diblock copolymers with M_n ranging from 120 to 300 kDa and 2VPy content between 10 and 15 mol% at the optimal conditions. Afterward, the developed membranes were evaluated in terms of their permeability towards water and in terms of their ability to retain two different microorganisms, namely, Enterococcus faecalis and Escherichia coli, that are known to be harmful to human health. The experimental water flux for a membrane with pore size around 60 nm was equal to 31,400 L h⁻¹ m² and expectedly decreased with the decrease in membrane pore diameter. The retention ability of membranes for Enterococcus faecalis and Escherichia coli was higher than 90%. In particular, the retention ability for Enterococcus faecalis was equal to 98.9% and for Escherichia coli was 91.4%. The toxicity of the produced membrane was also determined, and the measured value was relatively low, at 17%. Full article

In this paper, a new polymeric membrane including polymers (cellulose acetate, polyethylene glycol 400), copolymer poly(4-vinylpyridine)-block-polystyrene, and TiO₂ nanoparticles were synthesized by the phase inversion method. In order to investigate the presence and the influence of the TiO₂ nanoparticles on the membrane matrix, a polymeric membrane without TiO₂ nanoparticles was prepared by the same preparation method. The structure of the polymeric membranes was characterized by several techniques, such as Fourier transform infrared spectroscopy and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, thermogravimetric analysis, and impedance spectroscopy. Also, the water contact angle, water retention, and porosity were determined. The results showed that the TiO₂ nanoparticles were incorporated into the pores and onto the surface of the polymeric membrane, which resulted in a more uniform structure. In addition, these polymeric membranes were tested for the removal of cadmium ions from synthetic waste-water using a laboratory-scale electrochemical separation system with a custom-built setup. The results showed that the polymeric membrane with TiO₂ nanoparticles showed a high cadmium ions removal rate (95.53%), compared to the polymeric membrane without TiO₂ nanoparticles (85.29%), after a 1.5 h electrochemical separation test. The final results indicated that the polymeric membranes prepared with TiO₂ nanoparticles had excellent thermal stability and exhibited the best ionic conductivity. The electrochemical separation system proved that the obtained polymeric membranes effectively remove cadmium from the synthetic waste-water. Full article

Microbial biofilms pose significant medical and industrial challenges due to their resistance to conventional antimicrobials, accounting for 40–80% of bacteria in various environments. This resistance primarily results from the extracellular polymeric matrix, a protective network of sugars, proteins, and other molecules produced by bacteria. The matrix restricts antibiotic penetration, facilitates microbial communication, and retains nutrients. Consequently, novel strategies to counteract biofilms are under investigation. Fatty acids have emerged as promising prebiotic agents, defined as substances that stimulate the growth of beneficial bacteria. These compounds can disrupt biofilm structure and increase microbial susceptibility to treatment. Short- and medium-chain fatty acids demonstrate direct antimicrobial activity and can alter microbial community composition, thereby inhibiting biofilm formation in several pathogens, including oral species. For instance, omega-3 fatty acids effectively inhibit Staphylococcus aureus and Pseudomonas aeruginosa biofilms through membrane disruption and quorum sensing (QS) inhibition. Additionally, long-chain fatty acids, particularly omega-3 and omega-6 polyunsaturated fatty acids, exhibit anti-inflammatory and antibacterial properties. This review synthesises current evidence on fatty acids as prebiotics, emphasising their mechanisms of action and therapeutic potential against drug-resistant biofilm-associated infections. Given the increasing prevalence of antimicrobial resistance, unsaturated and essential fatty acids rep-resent promising candidates for innovative biofilm-control strategies. Full article

Polymeric membranes based on chitosan (Cs) were extracted from shrimp shells and evaluated. These membranes were modified using polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), and glycerol (Gly) and crosslinked with glutaraldehyde (GA) to examine their suitability for water filtration processes. The Cs exhibited high purity, a total nitrogen content of 6.49%, and an average molecular weight of 456 kDa, all of which are suitable for membrane formation. Four membranes (Cs-GA, B2: Cs-PEG, B5: Cs-PEG-PVP, and B7: Cs-Gly) were characterized by means of FTIR, SEM, AFM, thickness, contact angle, tensile testing, TGA, DSC, and filtration with distilled water at 4.83 bar. B2 and B5 showed thicknesses of 207 and 190 μm and contact angles of 56.7° and 58.9°, lower than that of Cs-GA (89.4°). In filtration, B2 achieved a flux of 2222.70 LMH, a permeance of 460.19 LMH·bar⁻¹, and a hydraulic resistance of 8.79 × 10¹¹ m⁻¹, while Cs-GA, B5, and B7 exhibited fluxes of 24.10, 40.43, and 24.77 LMH, respectively, permeances of 9.75, 8.37, and 5.13 LMH·bar⁻¹, and hydraulic resistances of 4.15 × 10¹³, 4.83 × 10¹³, and 7.89 × 10¹³ m⁻¹, in the same order. Overall, membranes B2 and B5 are recognized as the most promising for water filtration under pressured operating conditions. Full article

The study investigates the performance of polyethersulfone (PES) ultrafiltration (UF) membranes modified with a coating of polymerizable bicontinuous microemulsion (PBM) for membrane bioreactor (MBR) applications. Two types of PBM-modified PES membranes—casting-coated and spray-coated—were compared with a commercial PES membrane. A laboratory side-stream MBR (ssMBR) was employed to treat model wastewater (MW) with activated sludge under aerobic conditions. The fouling propensity of the membranes in ssMBR was evaluated through the implementation of two protocols: (i) flux-step test to treat low-strength domestic model wastewater (DMW) and (ii) constant flux test to treat high-strength olive mill model wastewater (OMW). The findings indicated that both the commercial PES and PBM spray-coated PES membranes started to critically foul at 36 L m⁻² h⁻¹. The PBM spray-coated membranes showed enhanced fouling resistance in comparison to the PBM casting-coated membranes. The deposition of the biofouling layer was the thinnest on PBM spray-coated membranes, which can be attributed to the low surface charge and high hydrophilicity of the modified membrane surface. In contrast, deposition of a thicker fouling layer was found on the commercial PES membrane, which can be attributed to the relatively higher surface charge promoting organic adsorption. A comparison of the fouling trends exhibited by commercial PES and PBM spray-coated membranes in OMW treatment revealed that they have similar fouling tendencies. However, a notable distinction emerged when the PBM spray-coated membrane was observed to demonstrate a lower fouling propensity accompanied by comparatively thinner fouling layers. The results demonstrate that the PBM spray-coated membranes have enhanced fouling resistance and filtration efficacy in MBRs treating wastewater with diverse strengths, thereby affirming their potential for application in wastewater treatment systems. Full article

Membrane separation is a promising, low-energy technology for purifying turquoise hydrogen from methane pyrolysis streams. However, there is a critical knowledge gap between the performance of membrane materials and the practical application of large-scale modules under realistic process conditions. This study evaluates commercial polyimide and polysulfone hollow fiber membranes for H₂/CH₄ separation. The effect of feed composition and pressure on the membrane separation performance were studied, revealing that the separation efficiency is overwhelmingly dominated by concentration polarization, which reduced the H₂/CH₄ separation factor by up to 80% compared to ideal values. Despite this, by optimizing process conditions, we successfully achieved a permeate purity of 99.3% H₂ at 85% recovery. Furthermore, Aspen Plus simulations of an integrated pyrolysis reactor with the membrane unit and a recycle stream demonstrate significant process benefits. The integration increased the H₂ production rate from 10.3 to 17.6 kmol/h and substantially reduced the specific energy consumption from 40.3 to 24.9 kJ/g H₂ compared to non-integrated systems. This work shows that a membrane process can improve not only the product H₂ purity but also the overall energy efficiency of a turquoise hydrogen production process. Full article

Magnetic biochars (MBCs) have been shown to inhibit the horizontal transfer of antibiotic resistance genes (ARGs) in soils, both with and without microplastics (MPs); however, the underlying molecular biological mechanisms remain unclear. This study examined the effects of MBCs and coexisting polybutylene adipate terephthalate microplastics (PBAT MPs) on the physiological characteristics of Serratia marcescens ZY01 (a host strain carrying the tet gene) and further investigated their relationships with the absolute abundance of the tet gene in soil. The results demonstrated that MBCs promoted prodigiosin synthesis in Serratia marcescens ZY01 by mediating the electron transfer process, the effect of which was further enhanced in the presence of PBAT MPs. In treatments without PBAT MPs, MBCs generally suppressed the production of both proteins and polysaccharides in the extracellular polymeric substances. In contrast, in treatments containing PBAT MPs, the protein content gradually decreased with decreasing iron-to-biochar ratios, while the polysaccharide content remained largely unchanged. MBCs also elevated intracellular ROS levels due to the increased oxidative stress, particularly in treatments with PBAT MPs. A positive correlation between intracellular ROS levels and cell membrane permeability indicates that intracellular ROS was the primary driver of the increased cell membrane permeability. The presence of MBCs and PBAT MPs generally provided favorable habitats for Serratia marcescens ZY01, thereby enhancing its cell viability. Mantel test analysis indicated that MBCs influenced Serratia growth in soil by modulating its cell viability. Furthermore, the increased intracellular ROS level was significantly positively correlated with the absolute abundance of the tet gene in soil, implying the horizontal transfer of the tet gene at the intra-genus level. These findings offer helpful insights for developing environmental remediation strategies based on biochar–iron composites. Full article

Virus filtration is an essential unit operation used to validate clearance of adventitious virus during the manufacture of biopharmaceutical products such as monoclonal antibodies. Obtaining at least a 10,000-fold reduction in virus particles in the permeate is challenging as monoclonal antibodies are about half the size of the virus particles. Minute virus of mice, FDA-recommended model adventitious virus, was labeled with a fluorescent dye. Laser scanning confocal microscopy was used to determine the location of virus entrapment within the virus filtration membrane. Three different hollow fiber membranes made of regenerated cellulose and polyvinylidene fluoride were tested. Feed streams consisted of MVM spiked in buffer and MVM spiked in 5 g L⁻¹ bovine serum albumin known to contain aggregates similar in size to the MVM. After filtering the feed, a buffer flush was used, with and without 30 min pause before the buffer flush. For all virus filters, a 30 min process pause led to broadening and movement of the virus entrapment zone deeper into the membrane. The presence of aggregates led to greater broadening of the entrapment zone. Both effects could lead to reduced virus clearance. Visualization of virus entrapment helps improve understanding of the behavior of virus filtration membranes. Full article

This work reports on the synthesis and ring-opening metathesis polymerization (ROMP) of two novel homologous sulfonyl-containing norbornene dicarboximide monomers, specifically, N-4-(trifluoromethylsulfonyl)phenyl-norbornene-5,6-dicarboximide (1a) and N-4-(trifluoromethylsulfonyl)phenyl-7-oxanorbornene-5,6-dicarboximide (1b) using the Grubbs 2nd generation catalyst (I). The polymers are thoroughly characterized by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), thermomechanical analysis (TMA), thermogravimetric analysis (TGA), atomic force microscopy (AFM), and X-ray diffraction (XRD), among other techniques. A comparative study of gas transport in membranes based on these ROMP-prepared polymers is performed and the gases studied are hydrogen, oxygen, nitrogen, carbon dioxide, methane, ethylene and propylene. It is found that the presence of sulfonyl pendant groups in the polymer backbone increases the gas permselectivity in slight detriment of the gas permeability compared to a polynorbornene dicarboximide lacking sulfonyl groups. The membrane of the sulfonyl-containing polymer with an oxygen heteroatom in the cyclopentane ring, 2b, is also found to have one of the largest permselectivity coefficients reported to date for the separation of H₂/C₃H₆ in glassy polynorbornene dicarboximides. Full article

The development of advanced macromolecular systems with tailored structural and functional properties is a key objective in modern materials science, particularly for biomedical applications such as targeted drug delivery. In this study, hydrogel (HG), a polymer-based formulation, was investigated as a functional carrier for the enhanced intradermal and transdermal delivery of propranolol hydrochloride (PRO-HCl), a highly water-soluble model compound, and its potential was compared to other vehicles easily obtained by pharmacists: ointment (OM), liposomal cream (LCR), and microemulsion (ME). The formulations were characterized by their physicochemical and rheological characteristics, and evaluated in vitro and ex vivo using vertical diffusion cells equipped with synthetic membranes, intact porcine skin, and skin pretreated with solid microneedles (MNs). The HG formulation exhibited superior release performance (2396.85 ± 48.18 μg/cm²) and the highest intradermal drug deposition (19.87 ± 4.12 μg/cm²), while its combination with MNs significantly enhanced transdermal permeation (p = 0.0017). In contrast, the synergistic effect of MNs and ME led to a pronounced increase in drug accumulation within the skin (up to 60.3-fold). These findings highlight the crucial role of matrix composition and properties in modulating molecular transport through biological barriers. The study demonstrates that polymeric HGs represent versatile, functional materials with tunable structural and mechanical features, suitable for controlled release and potential systemic delivery applications. Full article