Search Results (185)

Since 2014, a model of the individual response to ionizing radiation (IR), based on the radiation-induced nucleoshuttling of the ATM protein kinase (RIANS), has been developed by our lab: after irradiation, ATM dimers monomerize in cytoplasm and diffuse into the nucleus to trigger both recognition and repair of DNA double-strand breaks (DSB), the key-damage of IR response. Moderate radiosensitivity is generally caused by heterozygous mutations of ATM substrates (called X-proteins) that are over-expressed in cytoplasm and form complexes with ATM monomers, which reduces and/or delays the RIANS and DSB recognition. Here, we asked whether molecules, rather than X-proteins, can also influence RIANS. Caffeine was chosen as a potential “X-molecule” candidate. After incubation of cells with caffeine, cutaneous fibroblasts from an apparently healthy radioresistant donor, a patient suffering from Alzheimer’s disease (AD) and another suffering from neurofibromatosis type 1 (NF1) were exposed to X-rays. The functionality of ATM-dependent DSB repair and signaling was evaluated. We report here that caffeine molecule interaction with ATM leads to the inhibition of DSB recognition. This effect is significant in radioresistant cells. Conversely, in the AD and NF1 cells, the DSB recognition is already so low that caffeine does not provide any additional molecular effect. Full article

Pb (II) contamination in wastewater represents a grave threat to the environment and ecosystems. Consequently, there is an urgent need to prepare low-cost and highly efficient Pb (II) adsorbents. To address this need, abundant and low-cost natural silica-based desert sand (DS) was innovatively utilized as a carrier to develop efficient and selective Pb (II) adsorbents. Modified desert sand (MDS) was first prepared via 1 M HCl pretreatment for 2 h and subsequent KH550 silane modification. Pb (II)-imprinted composites (Pb (II)-IIP@MDS) were then fabricated via ion-imprinted polymerization, using Pb (II) as the template ion and N-hydroxymethacrylamide (NHMA)/hydroxyethyl methacrylate (HEMA) as dual functional monomers with a molar ratio of 1:1. The synthesized Pb (II)-IIP@MDS was comprehensively characterized by X-ray photoelectron spectrometer (XPS), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR). The adsorption capacity, selectivity, and reusability of this material for lead ions were evaluated through three experiments conducted within the optimized pH range of 6–7, with error bars indicated. In adsorption isotherm experiments, the initial Pb (II) concentration ranged from 50 to 500 mg·L⁻¹, conforming to the Langmuir model (R² = 0.992), with a theoretical maximum adsorption capacity reaching 107.44 mg·g⁻¹; this indicates that the adsorbate forms a monolayer adsorption on the homogeneous imprinted sites. Kinetics data indicate that the process best fits a quasi-first-order kinetic model (R² ≥ 0.988), while the favorable quasi-second-order kinetic fit (R² ≥ 0.982) reflects the synergistic effect of physical diffusion and ion-imprinting chemistry, reaching equilibrium within 120 min. Thermodynamic parameters (ΔH⁰ = 12.51 kJ·mol⁻¹, ΔS⁰ = 101.19 J·mol⁻¹·K⁻¹, ΔG⁰ < 0) confirmed endothermic, entropy-increasing, spontaneous adsorption. In multicomponent systems, Pb (II)-IIP@MDS showed distinct Pb (II) selectivity. It retained 80.3% adsorption efficiency after eight cycles. This work provides a promising strategy for fabricating low-cost, high-performance Pb (II) adsorbents, and Pb (II)-IIP@MDS stands as a practical candidate for the remediation of Pb (II)-contaminated wastewater. Full article

This study explores the potential of integrating thermoplastic surfaces into fiber-reinforced plastics (FRPs) to eliminate the need for extensive surface preparation prior to bonding. Traditional bonding techniques for FRPs, especially in aerospace applications, demand meticulous surface preparation to ensure adequate adhesion. As a potential alternative to conventional methods for generating adhesion, the formation of an interpenetrating polymer network (IPN) by diffusion of the epoxy monomers into a thermoplastic surface layer is investigated. The research involved manufacturing CFRP panels with thermoplastic surfaces, polyether sulfone (PES), and polyetherimide (PEI), followed by a bonding process with and without conventional surface preparation. The performance of the joints was tested by tensile shear and Mode-I fracture toughness tests and compared to reference samples without thermoplastic surfaces. The formation and characteristics of the IPNs were analyzed using optical microscopy, laser scanning microscopy, and energy-dispersive X-ray spectroscopy. The results demonstrate that PES surfaces, even without surface treatment, can provide high mechanical performance with shear strengths ranging from 18 MPa to 23 MPa. PEI surfaces led to a shear strength from 10 MPa up to 14 MPa, correlating to a less extensive IPN formation compared to PES. However, both thermoplastics significantly improved the bonding process performance without surface preparation. Full article

Effective metabolic waste clearance and maintaining ionic homeostasis are essential for the health and normal function of the central nervous system (CNS). To understand its mechanism and the role of fluid flow, we develop a multidomain electro-osmotic model of optic-nerve microcirculation (as a part of the CNS) that couples hydrostatic and osmotic fluid transport with electro-diffusive solute movement across axons, glia, the extracellular space (ECS), and arterial/venous/capillary perivascular spaces (PVS). Cerebrospinal fluid enters the optic nerve via the arterial parivascular space (PVS-A) and passes both the glial and ECS before exiting through the venous parivascular space (PVS-V). Exchanges across astrocytic endfeet are essential and they occur in two distinct and coupled paths: through AQP4 on glial membranes and gaps between glial endfeet, thus establishing a mechanistic substrate for two modes of glymphatic transport, at rest and during stimulus-evoked perturbations. Parameter sweeps show that lowering AQP4-mediated fluid permeability or PVS permeability elevates pressure, suppresses radial exchange (due mainly to hydrostatic pressure difference at the lateral surface and the center of the optic nerve), and slows clearance, effects most pronounced for solutes reliant on PVS–V export. The model reproduces baseline and stimulus-evoked flow and demonstrates that PVS-mediated export is the primary clearance route for both small and moderate solutes. Small molecules (e.g., A$\beta$) clear faster because rapid ECS diffusion broadens their distribution and enhances ECS–PVS exchange, whereas moderate species (e.g., tau monomers/oligomers) have low ECS diffusivity, depend on trans-endfoot transfer, and clear more slowly via PVS–V convection. Our framework can also be used to explain the sleep–wake effect mechanistically: enlarging ECS volume (as occurs in sleep) or permeability increases trans-interface flux and accelerates waste removal. Together, these results provide a unified physical picture of glymphatic transport in the optic nerve, yield testable predictions for how AQP4 function, PVS patency, and sleep modulate size-dependent clearance, and offer guidance for targeting impaired waste removal in neurological disease. Full article

Although covalently crosslinked gelatin hydrogels have been investigated for use in 3D cell culture due to inherent bioactivity and proliferation within the denatured collagen precursor, the stability of the matrix, and relatively inexpensive synthesis, current systems lack precise control over mechanical properties, including homogeneity, stiffness, and efficient diffusion of nutrients to embedded cells. Difficulties in modifying gel matrix composition and functionalization have limited the use of covalently crosslinked gelatin hydrogels as a three-dimensional (3D) cell culture medium, lacking the ability to tailor the microenvironment for specific cell types. In addition, the currently utilized chain-growth photopolymerization mechanism for crosslinking hydrogels has a potential for side reactions between the matrix backbone and components of the cell surface, requires a high concentration of radicals for initiation, and only cures with long irradiation times, which could lead to cytotoxicity. To overcome these limitations, a superfast curing reaction mechanism, in which a thiol monomer reacts efficiently with non-homopolymerizable alkenes, is suggested. This mechanism reliably produces a well-defined matrix that does not require a high radical concentration for photoinitiation. Mechanical customization of the hydrogel is largely achievable through variation in degree of functionalization of the gelatin backbone, dependent on reaction conditions such as pH, allyl concentration, and time. This work provides a mechanistic framework for GelAGE hydrogel fabrication by elucidating the molecular mechanism of gelatin functionalization with AGE and the thiol-ene crosslinking reactions controlling network stiffness. These insights provide the foundation for engineering hydrogels that mimic the viscoelastic and structural characteristics of cartilage, enabling advanced in vitro models for osteoarthritis research. Full article

Condensed tannins from grape seed residues show high antioxidant activity but low oral bioavailability because of their high degree of polymerization and covalent interactions with proteins. This study aimed to improve their bioaccessibility through depolymerization and encapsulation. Depolymerization was carried out using microwave-assisted SN1 reactions with gallic acid as a nucleophile under food-grade conditions, mainly producing epicatechin monomers with 99.8% polymer degradation efficiency. Importantly, the inhibition of ABTS●+ and DPPH● radicals remained unaffected (p > 0.05), indicating that depolymerization preserved the antioxidants’ redox function, maintaining about 90% of their inhibition activity. The products were encapsulated in phosphatidylcholine liposomes, which had nanometric sizes and high encapsulation efficiency (83.11%), and remained stable for up to 60 days. In vitro release of nanoliposomal epicatechin in a D1 simulant was less than 10% after 48 h, fitting a Weibull model (β = 0.07), suggesting sub-diffusive transport and demonstrating high bioactive retention capacity in aqueous systems. During in vitro digestion, bioaccessibility of gallic acid and epicatechin reached 95.61 ± 0.58% and 98.56 ± 0.81%, respectively, with a 2333% increase in the bioaccessible mass of flavan-3-ols in native liposomal condensed tannins, which otherwise showed no detectable bioaccessibility. These findings highlight the potential of polyphenols from agro-industrial waste with enhanced bioaccessibility for applications in nutraceuticals and functional foods. Full article

Poly(2-oxazoline) coatings with antibiofouling properties and good biocompatibility can also be deposited by the plasma polymerization method using 2-methyl-2-oxazoline and 2-ethyl-2-oxazoline as monomers. Plasma polymers are formed of various monomer fragments and recombination products. Commonly, plasma polymers are highly crosslinked structures created by many different fragments, preferably of no repeating unit. Thus, chemical analysis of plasma polymers is difficult. To obtain a better description of plasma polymerized poly(2-oxazoline) coatings, the analysis of their plasma deposition process was performed. The electron ionization of 2-methyl-2-oxazoline and 2-ethyl-2-oxazoline molecules was studied using the crossed electron–molecular beam technique with mass spectrometric detection of the produced ions. The chemical composition of gaseous compounds at plasma polymerization was determined by gas chromatography-mass spectrometry (GC-MS), ion mobility spectrometry (IMS) and optical emission spectroscopy (OES). Also, the chemical composition and antibacterial activity of the water leachates from previously deposited poly(2-oxazoline) films were tested using FTIR spectroscopy and the disk diffusion method, respectively. It was found that acetonitrile and propionitrile are the main neutral products created in the nitrogen discharge with 2-methyl-2-oxazoline and 2-ethyl-2-oxazoline monomers. The water leachates from deposited films do not exhibit any antibacterial activity. It was concluded that the antibacterial properties of POx films are due to their hydrophility. Full article

Polymer fouling in batch and tubular reactors creates safety hazards from heat buildup and blockages. The continuous Corning Advanced-Flow™ Reactor (AFR) offers enhanced mass and heat transfer, improving safety and efficiency. This study evaluated three reactor systems—a monolithic AFR, an AFR with an external pipe, and a conventional tubular reactor—for the mini-emulsion polymerization of styrene and subsequent styrene–acrylic acid copolymerization. The AFR operability under varying monomer concentrations was assessed and investigated, with the residence time’s effects on conversion. For styrene polymerization at 20–35 wt% monomer, the highest conversions achieved were 88.0% in the AFR, 85.8% in the tubular reactor, and 98.9% in the AFR with pipe. Uniform particles were obtained at ≤30 wt%, whereas at 35 wt%, the monolithic AFR experienced clogging and loss of particle uniformity. Similarly, in styrene–acrylic acid copolymerization (15–17.5 wt% monomer), the maximum conversions reached 80.1% in the AFR and 95.4% in the AFR with pipe, while the monolithic AFR again experienced blockage at 17.5 wt%. In conclusion, integrating an external pipe with the AFR, coupled with higher flow rates, significantly improved initiator diffusion, enhanced monomer conversion, and mitigated blockage. This approach enabled the efficient, continuous production of nanoscale, uniformly sized polystyrene and styrene–acrylic acid copolymers even at high monomer concentrations. Full article

This study investigates the influence of cellulose nanofibrils (CNFs) on the polymerization kinetics of methyl methacrylate (MMA) during in situ suspension polymerization at 70 °C (343.15 K). Four CNF concentrations were evaluated and compared to a reference system without CNFs. Polymerizations were carried out in a thermostatted flask immersed in an ethylene glycol bath and covered to ensure thermal stability. The temperature profiles of both the reaction medium and the surrounding bath were continuously recorded, allowing for the calculation of heat flow, polymerization rate (R_p), and monomer conversion. The incorporation of CNFs led to a significant increase in R_p and faster MMA conversion. This effect was attributed to the presence of nanocellulose within the polymerizing medium, which restricted diffusion and contributed to the onset of the phenomenon of autoacceleration. Additionally, CNFs promoted a higher total heat release, underscoring the need for thermal control during scale-up. The resulting material qualifies as a biocomposite, as biobased nanofibrils became integrated into the polymer matrix. These findings demonstrate that CNFs act as effective kinetic promoters in MMA polymerizations and may serve as functional additives to enhance both reaction performance and sustainability. However, safety considerations remain critical when transferring this approach to industrial processes. Full article

This study presents a quantitative electrophysiological method to directly measure the passive transport of ammonium ions through bacterial outer membrane porins. Using a zero-current reversal potential assay in planar lipid bilayers under defined bi-ionic gradients, this study evaluates the permeability of ammonium salts through two general diffusion porins: Omp-Pst2 from Providencia stuartii and OmpF from Escherichia coli. Under matched ionic conditions, Omp-Pst2 exhibited significantly higher ammonium flux—approximately 6000 ions per second per monomer at a 1 µM gradient—compared to ~4000 ions per second for OmpF. Importantly, the identity of the accompanying anion (chloride vs. sulfate) modulated both the ion selectivity and flux rate, highlighting the influence of counterion interactions on porin-mediated transport. These findings underscore how structural differences between porins—such as pore geometry and charge distribution—govern ion permeability. The method applied here provides a robust framework for quantifying nutrient flux at the single-channel level and offers novel insights into how Gram-negative bacteria may adapt their membrane transport mechanisms under nitrogen-limited conditions. This work not only enhances our understanding of outer membrane permeability to small ions like ammonium, but also has implications for antimicrobial strategy development and biotechnological applications in nitrogen assimilation. Full article

An engineered molecular motor composed of an ATP-dependent kinesin-1 monomer and an ATP-independent diffusing microtubule-associated protein is proposed, and its dynamics are studied theoretically. It is shown that the engineered motor can move directionally on microtubules towards the plus end, bearing great potential for applications in therapeutics or nanorobotics. The engineered motor can have an unloaded velocity similar to the wild-type kinesin-1 dimer, can take a mechanical (either forward or backward) step by hydrolyzing an ATP molecule under any load, and can generate the maximum force that is about half of that generated by the wild-type kinesin-1 dimer. Full article

Chiral covalent organic frameworks (COFs) hold great promise in heterogeneous asymmetric catalysis due to their designable structures and well-defined chiral microenvironments. However, precise control over the pore size of chiral COFs to optimize asymmetric catalytic performance remains challenging. Herein, we designed a proline-derived dihydrazide chiral monomer (L-DBP-Boc), which was subjected to Schiff-base reactions with two aromatic aldehydes of different lengths, 1,3,5-triformyl phloroglucinol (BTA) and 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde (TZ), to construct two hydrazone-linked chiral COFs with distinct pore sizes (L-DBP-BTA COF and L-DBP-TZ COF). Interestingly, the Boc protecting groups were removed in situ during COF synthesis. We systematically investigated the catalytic performance of these two chiral COFs in asymmetric aldol reactions and found that their pore sizes significantly influenced both catalytic activity and enantioselectivity. The large-pore L-DBP-TZ COF (pore size: 3.5 nm) exhibited superior catalytic performance under aqueous conditions at room temperature, achieving a yield of 98% and an enantiomeric excess (ee) value of 78%. In contrast, the small-pore L-DBP-BTA COF (pore size: 2.0 nm) showed poor catalytic performance. Compared to L-DBP-BTA COF, L-DBP-TZ COF demonstrated a 1.69-fold increase in yield and a 1.56-fold enhancement in enantioselectivity, possibly attributed to the facilitated diffusion and transport of substrates and products within the larger pore, thus improving the accessibility of active sites. This study presents a facile synthesis of pyrrolidine-functionalized chiral COFs and establishes the possible structure–activity relationship in their asymmetric catalysis, offering new insights for the design of efficient chiral COF catalysts. Full article

Monomer-to-excimer transition has become a valuable technique in fluorescence imaging because of its ability to enhance imaging contrast. However, from a practical perspective, the accuracy of excimer formation at target sites warrants further exploration. Enzyme-triggered peptide self-assembly provides a promising solution to this limitation. As a proof-of-concept, in this study, we developed a furin-triggered peptide self-assembling fluorescent probe RF-Cou by coupling a coumarin dye 7-(diethylamino)-2-oxo-2H-chromene-3-carboxylic acid (Cou) with a furin-responsive peptide scaffold for precision live-cell imaging. Upon entering furin-overexpressing 4T1 tumor cells, RF-Cou underwent enzymatic cleavage, releasing an amphiphilic peptide motif and self-assembling into nanoparticles largely concentrated in the Golgi apparatus to confine the diffusion of Cou. During this process, the Cou excimers were formed and induced a red shift in the fluorescence emission, validating the feasibility of RF-Cou in efficient excimer imaging of furin-overexpressing tumor cells. We expect that our findings will highlight the potential of stimuli-responsive small molecular peptide probes to advance excimer-based imaging platforms, particularly for enzyme-specific cell imaging and therapeutic monitoring. Full article

The need for renewable alternatives to petroleum-based polymers is growing in response to environmental concerns and resource depletion. Polyimides (PIs), which are traditionally synthesized from petroleum-derived monomers, raise sustainability issues. In this work, renewable 2,5-furandicarboxylic acid (FDCA) was employed as a sustainable feedstock to synthesize a bio-based diamine monomer, N,N′-bis(4-aminophenyl)furan-2,5-dicarboxamide (FPA). Subsequently, FPA was polymerized with various aromatic dianhydrides through thermal imidization, yielding four distinct bio-based polyimide (FPA-PI) films. The resulting films exhibited exceptional thermal stability, with 5% weight loss temperatures exceeding 425 °C and char yields ranging from 54% to 60%. Mechanical characterization revealed high elastic moduli (2.14–3.20 GPa), moderate tensile strengths (50–99 MPa), and favorable aging resistance. Gas permeation tests demonstrated promising CO₂/N₂ separation performance, with FPA-DODDA achieving superior CO₂/N₂ selectivity (27.721) compared to commercial films such as Matrimid^®, polysulfone, and polycarbonate, while FPA-BPFLDA exhibited enhanced CO₂ permeability (P(CO₂) = 2.526 Barrer), surpassing that of Torlon^®. The CO₂/N₂ separation performance of these FPA-PI films is governed synergistically by size-sieving effects and solution-diffusion mechanisms. This work not only introduces a novel synthetic route for bio-based polymers but also highlights the potential of replacing conventional petroleum-based materials with renewable alternatives in high-temperature and gas separation applications, thereby advancing environmental sustainability. Full article

This study presents a sustainable approach to transform waste cooking oil (WCO) into a multifunctional 3D-printable photocurable elastomer with integrated self-healing capabilities. A linear monomer, WCO-based methacrylate fatty acid ethyl ester (WMFAEE), was synthesized via a sequential strategy of transesterification, epoxidation, and ring-opening esterification. By copolymerizing WMFAEE with hydroxypropyl acrylate (HPA), a novel photocurable elastomer was developed, which could be amenable to molding using an LCD light-curing 3D printer. The resulting WMFAEE-HPA elastomer exhibits exceptional mechanical flexibility (elongation at break: 645.09%) and autonomous room-temperature self-healing properties, achieving 57.82% recovery of elongation after 24 h at 25 °C. Furthermore, the material demonstrates weldability (19.97% retained elongation after 12 h at 80 °C) and physical reprocessability (7.75% elongation retention after initial reprocessing). Additional functionalities include pressure-sensitive adhesion (interfacial toughness: 70.06 J/m² on glass), thermally triggered shape memory behavior (fixed at −25 °C with reversible deformation/recovery at ambient conditions), and notable biodegradability (13.25% mass loss after 45-day soil burial). Molecular simulations reveal that the unique structure of the WMFAEE monomer enables a dual mechanism of autonomous self-healing at room temperature without external stimuli: chain diffusion and entanglement-driven gap closure, followed by hydrogen bond-mediated network reorganization. Furthermore, the synergy between monomer chain diffusion/entanglement and dynamic hydrogen bond reorganization allows the WMFAEE-HPA system to achieve a balance of multifunctional integration. Moreover, the integration of these multifunctional attributes highlights the potential of this WCO-derived photocurable elastomer for various possible 3D printing applications, such as flexible electronics, adaptive robotics, environmentally benign adhesives, and so on. It also establishes a paradigm for converting low-cost biowastes into high-performance smart materials through precision molecular engineering. Full article