Biomacromolecules最新文献

Controlling ice growth is crucial during the cryopreservation of cells, but the current application of small molecules as cryoprotectants still remains a challenge. Inspired by structures of natural antifreeze (glyco)proteins, in this work, functionalized poly(l-methionine)s (PMets) are synthesized with different side groups including hydroxyl, threonine-mimetic with both methyl and hydroxyl groups (PMet-MOH), zwitterion with carboxyl and sulfonium (PMet-COOH), glycerol, and trehalose pendants. Results suggest that these functionalized PMets tend to self-assemble into 100-300 nm nanoparticles with positive charges in water. The functional structures have a remarkable influence on their ice control properties. It is supposed that PMet-MOH inhibits ice growth possibly through the adsorption mechanism by adjacent methyl and hydroxyl groups, whereas trehalose-tethered PMet can restrict diffusion of water molecules with the strongest ice recrystallization inhibition activity and zwitterionic PMet-COOH promotes ice nucleation obviously. This work offers valuable insight into the development of functional polypeptides as promising biocompatible cryoprotectants.

Membrane proteins play central roles in cell physiology and are the targets of over 50% of FDA-approved drugs. In the present study, we prepared single alkyl-chained triglucosides decorated with multiple pendants, designated multiple pendant-bearing glucosides (MPGs), to enhance membrane protein stability. The new detergents feature two and four pendants of varying size at the hydrophilic-lipophilic interfaces, designated MPG-Ds and MPG-Ts, respectively. When tested with model membrane proteins, including the human adrenergic receptor (β₂AR), the tetra-pendant-bearing MPGs (MPG-Ts) demonstrated superior performance compared to the dipendant analogs (MPG-Ds) and the gold standard DDM. All-atom molecular dynamics (MD) simulations results reveal that the four-pendant configuration of this detergent is remarkably effective in excluding water from the hydrophobic micelle interiors compared to the dipendant MPGs and DDM, an unprecedented feature of this new detergent. Our findings provide a novel strategy for designing water-resistant detergents, advancing the field of membrane protein research.

Developing new biodegradable polyesters with well-defined structures is of interest. We reported an attractive two-component aliphatic polyester-based thermoset, which was prepared via the esterification of biomass-derived l-malic acid oligomers and three-arm poly(ε-caprolactone) (3a-PCL) triols. The chemical network formed via the ester bonding and physical network caused by the crystallization of a 3a-PCL arm chain coexist in the thermoset, and the competition of the two characteristic networks leads to a negative correlation between the degree of covalent cross-linking and the degree of crystallization; thereby, the mechanical state of the thermosets can be easily tuned: from the plastic to elastomer state. Moreover, the crystallization temperature and melting point of the thermosets range in 30 °C ∼ 50 °C and -7 °C ∼ 18 °C, respectively, which are favorable for shape morphing as the thermosets are used as shape-memory materials. This work also provides valuable information about tailoring the mechanical and thermal properties of star-shaped polyester-based thermosets.

Corneal persistent epithelial defects are common ophthalmic injuries that can cause significant visual and structural damage. While diagnosis is straightforward, treatment remains challenging. Noninvasive therapies like eye drops are preferred, but severe neurotrophic keratopathy may require surgical interventions. This study explores gelatin-based hydrogels as noninvasive alternatives for corneal repair. Four photo-cross-linkable hydrogels with gelatin and riboflavin phosphate (RFP) were evaluated: a control and variants incorporating 2.5% dextran (D), 0.4% hyaluronic acid (HA), or 1% methylcellulose (MC). In vitro assessments included physicochemical properties, biocompatibility, and release kinetics alongside ex vivo wound healing assays. The gelatin-RFP hydrogel maintained corneal transparency, while additives reduced it. Dextran slowed compound release, and HA and MC reduced the release rate of larger molecules. All hydrogels showed excellent biocompatibility, and ex vivo models confirmed re-epithelialization, though slower than controls. The unmodified gelatin-RFP hydrogel demonstrated the best potential for corneal tissue engineering, supporting its future clinical translation.

Synthesis of high-molecular-weight polypeptides and their block copolymer macromolecular architectures from β-sheet-promoting L-amino acids is still an unresolved problem. Here, an elegant steric hindrance-assisted ring-opening polymerization (SHAROP) strategy is introduced to access β-sheet poly(L-tyrosine) having more than 250 units. The scope of the synthetic methodology is expanded to access unexplored poly(L-tyrosine)-based higher-order β-sheet block copolymer nanoassemblies. In this strategy, a tert-butyl benzyl unit is employed as a steric handle that imbibes the solubility by promoting the α-helical conformation in the propagating polypeptide chains. The living ROP process enables the synthesis of well-defined block copolymers initiated by poly(L-tyrosine) living-chain ends or growing the poly(L-tyrosine) chains from the pre-existing macroinitiators of poly(L-glutamate) or poly(L-lysine). Acid-catalyzed postpolymerization deprotection restores the poly(L-tyrosine) blocks in their nascent β-sheet conformations. Thioflavin-T fluorescence assay establishes the β-sheet core-shell structures of these nanoassemblies, which are found to be nontoxic to mammalian cell lines.

We use a combination of Brownian dynamics (BD) simulation results and deep learning (DL) strategies for the rapid identification of large structural changes caused by missense mutations in intrinsically disordered proteins (IDPs). We used ∼6500 IDP sequences from MobiDB database of length 20-300 to obtain gyration radii from BD simulation on a coarse-grained single-bead amino acid model (HPS2 model) used by us and others [Dignon, G. L. PLoS Comput. Biol. 2018, 14, e1005941,Tesei, G. Proc. Natl. Acad. Sci. U.S.A. 2021, 118, e2111696118,Seth, S. J. Chem. Phys. 2024, 160, 014902] to generate the training sets for the DL algorithm. Using the gyration radii ⟨R_g⟩ of the simulated IDPs as the training set, we develop a multilayer perceptron neural net (NN) architecture that predicts the gyration radii of 33 IDPs previously studied by using BD simulation with 97% accuracy from the sequence and the corresponding parameters from the HPS model. We now utilize this NN to predict gyration radii of every permutation of missense mutations in IDPs. Our approach successfully identifies mutation-prone regions that induce significant alterations in the radius of gyration when compared to the wild-type IDP sequence. We further validate the prediction by running BD simulations on the subset of identified mutants. The neural network yields a (10⁴-10⁶)-fold faster computation in the search space for potentially harmful mutations. Our findings have substantial implications for rapid identification and understanding of diseases related to missense mutations in IDPs and for the development of potential therapeutic interventions. The method can be extended to accurate predictions of other mutation effects in disordered proteins.

Stimuli-responsive polymeric vehicles can change their physical or chemical properties when exposed to internal or external triggers, enabling precise spatiotemporal control of drug release. Nevertheless, systematic research is lacking in preparing dual stimuli-responsive amphiphilic block copolymers with different hydrophilic/hydrophobic block ratios in forming self-assembled structures. Here, we synthesized two types of block copolymers consisting of the hydrophobic segments (i.e., pH-responsive 2-(diethylamino)ethyl methacrylate (DEA) and ultrasound-responsive 2-methoxyethyl methacrylate (MEMA)) and hydrophilic poly(ethylene glycol) methyl ether (mPEG) segments, forming mPEG_X-b-P(DEA_Y-co-MEMA_Z). These amphiphilic block copolymers can self-assemble to form polymeric micelles, and their structures (e.g., size) and properties (e.g., critical vesicle concentration, stability, stimuli-responsiveness to pH and ultrasound, drug loading efficiency, and controlled drug release performance) were thoroughly investigated. In vitro cell studies further demonstrate that ultrasound can efficiently trigger drug release from polymeric micelles, emphasizing their potential for controlled drug delivery in therapeutic applications.

Cellulose nanocrystal (CNC) fillers have been shown to significantly improve the performance of polymer composites and hydrogels, elevating both strength and toughness. Polymer grafting from the surface of the nanocrystals has been employed to enhance matrix-filler interactions and keep the fillers dispersed within the matrix. However, such approaches often rely on multistep syntheses and diligent process control. Here, we propose modifying the nanocrystal surface to carry vinyl moieties, turning the particles into cross-linking comonomers. Using allyl glycidyl ether in an aqueous modification route, we were able to decorate the CNCs with varying amounts of vinyl moieties. Subsequent dispersion in 2-hydroxy methacrylate and thermally initiated free radical polymerization yielded composite materials that showed superior mechanical performance compared to those obtained from monomeric cross-linkers and unmodified CNCs. The large discrepancies in the observed glass transition temperatures of the obtained materials suggest, however, that the impact of the fillers on the polymerization kinetics is significant and less easily explained.

The extracellular matrix (ECM) plays a crucial role in organoid cultures by supporting cell proliferation and differentiation. A key feature of the ECM is its mechanical influence on the surrounding cells, directly affecting their behavior. Matrigel, the most commonly used ECM, is limited by its animal-derived origin, batch variability, and uncontrollable mechanical properties, restricting its use in 3D cell-model-based mechanobiological studies. Poly(2-alkyl-2-oxazoline) (PAOx) synthetic hydrogels represent an appealing alternative because of their reproducibility and versatile chemistry, enabling tuning of hydrogel stiffness and functionalization. Here, we studied PAOx hydrogels with differing compressive moduli for their potential to support 3D cell growth. PAOx hydrogels support spheroid and organoid growth over several days without the addition of ECM components. Furthermore, we discovered intestinal organoid epithelial polarity reversion in PAOx hydrogels and demonstrate how the tunable mechanical properties of PAOx can be used to study effects on the morphology and oxygenation of live multicellular spheroids.

Callose, a polysaccharide closely related to cellulose, plays a crucial role in plant development and resistance to environmental stress. These functions are often attributed to the enhancement by callose of the mechanical properties of semiordered assemblies of cellulose nanofibers. A recent study, however, suggested that the enhancement of mechanical properties by callose might be due to its ability to order neighboring water molecules, resulting in the formation, up to room temperature, of solid-like water-callose domains. This hypothesis is tested by atomistic molecular dynamics simulations using ad hoc models consisting of callose and cellulose hydrogels. The simulation results, however, do not show significant crystallinity in the callose/water samples. Moreover, the computation of the Young's modulus gives nearly the same result in callose/water and in cellulose/water samples, leaving callose's ability to link cellulose nanofibers into networks as the most likely mechanism underlying the strengthening of the plant cell wall.