Biomacromolecules最新文献

Protein-based materials can be engineered to derive utility from the structures and functions of the incorporated proteins. Modern methods of protein engineering bring promise of unprecedented control over molecular and network design, which will enable new and improved functionalities in materials that incorporate proteins as functional building blocks. For these advantages to be fully realized, there is a need for robust methods for producing protein-based networks, as well as methods for tuning their mechanical properties. Light-based 3D-printing techniques afford high-resolution fabrication capability with unparalleled design freedom in an inexpensive and decentralized capacity. This work features 3D-printed serum albumin-based bioplastics with mechanical properties modulated through the incorporation of glycerol or hyperbranched poly(glycerol)s (HPGs) as plasticizers. These materials capitalize upon important features of serum albumin, including its low intrinsic viscosity, high aqueous solubility, and relatively low cost. The incorporation of glycerol or HPGs of different sizes resulted in softer and more ductile bioplastics than those obtained natively without additives. These bioplastics showed shape-memory behavior and could be used to fabricate functional objects. These materials are accessible, possess minimal chemical hazards, and can be used for fabricating rigid and strong as well as soft and ductile parts using inexpensive commercial 3D printers.

Mesh suture is an emerging technology for closing high-tension soft tissue wounds. However, bulky mesh surgical knots can irritate surrounding tissue and harbor bacteria, leading to an increased risk of infection and palpability. Thus, a degradable knotless anchoring system is needed to secure mesh sutures. Here, novel anchor clip devices are fabricated via continuous liquid interface production (CLIP) three-dimensional (3D) printing using poly(propylene fumarate-co-propylene succinate) (PPFPS) oligomers. Thiol-ene cross-linking yields fully degradable thermoset devices with tunable mechanical properties. For comparison, high-resolution anchor clips are also fabricated via traditional injection molding using poly(l-lactide-co-glycolide) (PLGA). The PLGA anchor clips show similar mechanical performance to predicate soft tissue fixation techniques in a benchtop abdominal wall reconstruction model. Both PLGA and PPFPS anchor clips demonstrate satisfactory in vivo biocompatibility in a porcine abdominal implantation model. This work outlines the development of bioresorbable anchor clips for soft tissue fixation and illustrates their potential for clinical translation.

A recent method for producing amphiphilic block copolymers and nano-objects based on the ring-opening polymerization-induced self-assembly (ROPISA) in aqueous buffer is explored with respect to the tunability toward nanostructures. ROPISA gives rise to polypeptide copolymers with unprecedented levels of organization. By employing amphiphilic block copolymers of poly(ethylene glycol) (PEG) with the synthetic polypeptide poly(γ-benzyl-l-glutamate) (PBLG) and a combination of static (¹³C NMR, X-ray scattering, polarizing optical microscopy), thermodynamic (differential scanning calorimetry), and dynamic (dielectric spectroscopy) probes, we demonstrate a record of six levels of organization only found before in natural materials. These levels of organization could not be obtained in earlier morphology investigations of copolymers based on PEG and PBLG prepared by different methods. Furthermore, the type of NCA monomer (BLG-NCA vs Leu-NCA) and the solvent treatment method had an influence on the degree of segregation, the α-helical content, and the order-to-disorder transition temperature in the PEG-b-PBLG and PEG-b-PLeu copolymers.

Herein, we synthesized a pair of oxidized bisindolyl derivatives with anthracene (probe 1) and pyrene (probe 2) fluorophores for selective protein aggregate detection, crucial in disorders like Alzheimer's disease. Probe 1 exhibited a significant "turn-on" response (∼12-fold) and concomitant red shift (∼21 nm) with lysozyme aggregates, while showing ∼3-fold fluorescence enhancement with insulin aggregates, indicating high selectivity for aggregated proteins. Probe 2 showed similar responses but with less preference, as compared to probe 1. Furthermore, the thiazole orange (TO) assay confirmed the ability of probe 1 to detect protein fibrils and monitor aggregation kinetics (with distinct responses at different phases of aggregation). Molecular docking calculations demonstrated efficient binding of probes to aggregated proteins, stabilized primarily by hydrophobic interactions (π-π stacking). Additionally, density functional theory (DFT)-based global reactivity descriptors were computed to assess the reactivity and preferential docking sites. This work underscores the potential for novel therapeutic strategies targeting protein aggregates and early diagnosis of protein disorders.

We report on the synthesis, characterization, and properties of dextran polymers, which are covalently bridged/cross-linked by azobenzene moieties. The reversible photoactivity of the azo moiety is retained in the polymers, and the kinetics of the E/Z isomerization depend on the dextran/azobenzene ratio. Together with the simple preparation, our approach provides convenient access to photoresponsive sustainable materials. Moreover, based on the water-soluble polymers, we have prepared photoresponsive hydrogels, which soften upon UV irradiation. Our findings are based on spectroscopy (UV/vis, IR, and NMR/DOSY), size exclusion chromatography, and rheology.

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.

Low-molecular-weight oligopeptides can be electrospun into nanofiber mats. However, the mechanism underlying their electrospinnability is not well-understood. In this study, we used solid-phase peptide synthesis to produce the oligopeptide FFKK, to which the aromatic end-capping groups naphthalene, pyrene, and tetraphenylporphyrin were attached. Nuclear magnetic resonance, circular dichroism, and electrospray ionization mass spectrometry were used to characterize the oligopeptide structures. We investigated the effect of end-caps and oligopeptide concentration on their self-assembly as well as on their electrospinnability in fluorinated solvents. All oligopeptides with aromatic end-caps were amenable to electrospinning. Attenuated total reflectance Fourier transform infrared spectroscopy and microrheology results support the hypothesis that at sufficiently high concentrations, the self-assembled structures interact strongly, which facilitates electrospinning. Moreover, the results from this fundamental study can be extended to nonpeptidic small molecules possessing strong intermolecular interactions.