Biomacromolecules最新文献

Cellulose-based materials have been widely studied due to their biodegradability and excellent mechanical strength. However, the intrinsic brittleness of cellulose limits its applications. In this study, the bacterial cellulose-chitosan films were prepared by a casting method. The cellulose films with ≤ 30% chitosan exhibited a simultaneous increase in strength and toughness. The slippage of cellulose chains and dense network structure contribute to the improved strength and toughness of the cellulose-chitosan films. Besides, coarse-grained molecular dynamics simulations were performed to investigate the effects of different molecular factors (i.e., chain length, molecular interaction strength, and density) on the mechanical properties of cellulose-chitosan films. These molecular factors exhibited opposite effects on the tensile strength and strain at break. In particular, modifying the density of cellulose-chitosan films could simultaneously improve the strength and toughness significantly without sacrificing the elastic modulus. The findings provide physical insights into the strengthening and toughening effects of the cellulose-chitosan films.

We report the biological evaluation of bis-MPA dendrimers terminated with either cysteamine (CYS) or 2-(dimethylamino)ethanethiol (DA) groups for siRNA transfection. The results show that aggregation phenomena are critical to the biological performance of these constructs. Confocal and 2D microscopy demonstrated that only the G3-CYS dendrimer transported siRNA into cells. Accordingly, G3-CYS-mediated siRNA transfection reduced intracellular levels of the target proteins─p42-MAPK, Rheb, and MGMT─to 15-25% of control levels in a human glioblastoma cell line and mouse astrocytes. G3-CYS transfection efficiency was similar to that of commercial transfectants. However, its self-degradable bis-MPA backbone and tunable peripheral groups render it markedly superior, making it a promising transfection agent and emphasize the critical balance between structural design, biological efficacy, and safety. Despite its efficacy, G3-CYS displayed a narrow therapeutic window with pronounced cytotoxicity above 1 μM. In vivo studies further confirmed dose-dependent systemic toxicity, likely associated with enhanced blood coagulation.

Similar to cellulose nanocrystals (CNCs), rod-shaped chitin nanocrystals (ChNCs) form liquid-crystalline cholesteric (chiral nematic) suspensions in water. In this paper, we report how the biological source from which the ChNCs were obtained influences the properties of their liquid-crystalline suspensions, specifically their phase separation diagram and helical pitch. We isolated ChNCs under the same acid hydrolysis conditions from chitin of various biological sources, i.e., snow crab, shrimp, Antarctic krill, squid, black soldier fly pupae, and oyster mushroom, and investigated their geometrical dimensions and surface charges as well as their liquid-crystalline suspension. Our key result is that the biological source has indeed a major impact on the length and the aspect ratio of the ChNCs, which in turn significantly influences the stability range and the helical pitch of their chiral-nematic aqueous suspensions. Remarkably, a much smaller helical pitch was observed for ChNCs derived from oyster mushroom. Overall, it has become clear that the biological origin of ChNCs indeed matters for their properties and their potential applications.

Targeted drug delivery systems that are stimuli-responsive offer great potential for enhancing the therapeutic activity of drugs, decreasing off-target effects, and improving bioavailability. This proof-of-concept study introduces an amphiphilic drug delivery system (DDS) capable of loading hydrophobic cargo. Elevated glutathione (GSH) levels, characteristic of certain types of cancer cells' microenvironment, degrade the nanostructures and release the cargo. Linear polyglycerol sulfate (LPGS), known for its excellent biocompatibility, is combined with lipoic acid (LA). LA facilitates the formation of cross-linked nanosheet amphiphiles sensitive to reductive conditions. Morphological changes are observed by scanning electron microscopy (SEM), cryogenic transmission electron microscopy (Cryo-TEM), and cryogenic electron tomography (Cryo-ET) upon UV irradiation (hν), creating a stable aggregate for loading hydrophobic cargo and assembling into sheets at elevated concentrations. The resulting material displays controlled release of model dyes under increased levels of GSH, tunable by the polymer size and LPGS:LA acid ratios. This behavior enhances targeted therapy and reduced off-target effects. Further loading with paclitaxel and subsequent release, together with in vitro assays, demonstrates the system's compatibility with an anticancer drug.

Parkinson's disease (PD) is difficult to treat clinically and lacks an effective treatment. The aim of this study was to synthesize and characterize butyrate-modified hyaluronic acid (HA-But), validate its therapeutic efficacy, and elucidate its mechanisms of action in PD. Behavioral tests, including the open field test, Y-maze, and elevated plus maze test, demonstrated that HA-But significantly alleviated motor dysfunction in PD mice. ELISA results indicated a marked reduction in pro-inflammatory cytokine levels following the HA-But treatment. In addition, immunohistochemistry, immunofluorescence, and Western blot analyses revealed that HA-But improved dopaminergic neuron survival and reduced α-synuclein aggregation. Furthermore, HA-But activated PINK1/Parkin-mediated mitophagy, modulated gut microbiota composition, and increased short-chain fatty acid (SCFA) levels, especially butyric acid. Combining HA-But with gastrodin further improved the PD symptoms in mice. These findings suggested the potential of HA-But as a novel approach for PD treatment.

Understanding the long-term stability of cellulose nanofibers is critical for their practical application in advanced functional materials. In this study, we investigated the aging behavior of phosphorylated cellulose nanofibers (PCNFs) sheets under moist-heat accelerated aging conditions (80 °C, 65% relative humidity (RH)) for up to 42 days. PCNFs with different phosphate group densities were prepared by controlling the phosphorylation time, and their chemical and morphological changes were systematically analyzed. Liquid-sta³¹P NMR revealed a progressive transformation of surface phosphate esters into inorganic phosphate salts during aging. This dephosphorylation was thought to lead to a decrease in the pH within the sheets, which in turn promoted hydrolysis of the cellulose backbone. The resulting degradation manifested as decreases in the degree of polymerization (DP) and fibril length, particularly in PCNFs with higher surface charge. Conversely, the lateral crystallite size of the cellulose increased. These findings provide insights into PCNF aging and highlight the importance of controlling the initial phosphate ester structure and environmental conditions to increase the stability of PCNF-based materials in practical applications.

Biomimetic materials are of significant interest in applications such as soft tissue repair, with their ability to replicate morphology and properties of native tissue. This study reports a novel thermoplastic polyurethane (TPU) synthesized with an amino acid-based diisocyanate hard segment. The effects of hard segment percentage on the mechanical, thermal, and hydrophilic properties were assessed. The optimal TPU shows a Young's modulus of 0.19 MPa, a tensile strength of 0.61 MPa, and an elongation at break of 2375%. Incorporating a novel functionalized clay in this TPU gives excellent antibacterial properties, demonstrating efficacy against both Gram-positive and Gram-negative bacterial strains. The addition of this clay also significantly enhances the mechanical properties of the TPU, with Young's modulus increasing by up to 26 times with 3 wt % clay. The TPU was spun into fibers, creating a fibrous scaffold mimicking the architecture of some soft tissues. The TPU fibers exhibit a considerably higher tensile strength compared to bulk TPU while maintaining a high elongation at break. These TPUs and TPU-clay nanocomposites may find potential applications in soft tissue scaffolds or patches with antibacterial or anti-inflammatory behavior, for example, for the repair of gastrointestinal tissue that may be exposed to harmful bacteria.

We introduce generation-specific thermoresponsive dendrons that undergo reversible, temperature-triggered conformational changes with an "umbrella-like" conformation. Built from sequence-defined polymer segments via chemoselective iterative coupling, where we could independently control the stimulus response within each generational layer to obviate cooperative behavior. This noncooperative LCST transition enables selective collapse or expansion within individual generational layers. When grafted to gold nanoparticles with distinct thermal transition states, they form tunable umbrella-like architectures that control grafting density, footprint, and peripheral chain coverage. This structural modulation directly impacts the catalytic activity for the reduction of methylene blue in water, where reaction rates are governed by the balance between accessible gold active sites and diffusion through the polymer corona. These dendritic surface-grafted architectures maintained exceptional colloidal stability while preserving high catalytic accessibility, establishing a versatile platform for stimuli-responsive nanomaterials in catalysis, sensing, and biomolecular recognition.