Macromolecular Chemistry and Physics最新文献

The development of nanocarriers for nucleic acid delivery has gained significant attention as a promising strategy to regulate protein expression. Small interfering RNA (siRNA) is a powerful tool for gene silencing; however, it is rapidly degraded in the human body and cannot passively cross cell membranes due to its size and strong negative charge. To protect siRNA and facilitate intracellular delivery, a spermine-based polyacrylamide with a hydrophobic side chain was utilized as a carrier system. This polymer demonstrated high encapsulation efficiency, forming nanoparticles below 150 nm in size with a slightly positive zeta potential and low polydispersity at N/P ratios of 5 and 7. Additionally, the formulation process proved to be highly reproducible and scalable using a microfluidic mixing method. Moreover, siRNA-polyplexes exhibited good biocompatibility and maintained high cell viability post-transfection. In vitro, they demonstrated strong knockdown efficiency in murine fibroblasts (L929), murine lung epithelial cells (MLE12), human lung adenocarcinoma cells (A549), and human cervix adenocarcinoma cells (HeLa-GFP). Furthermore, the polyplexes promoted rapid cellular uptake and efficient endosomal escape, ensuring effective intracellular delivery. Given the therapeutic potential of siRNA, particularly for diseases lacking effective treatments, this approach holds significant promise for targeting solid tumors and fibrotic disorders.

Catalase is an enzyme that is useful for the degradation of toxic H₂O₂, which has been used for immobilization by using chemically modified polyhedral oligomeric silsesquioxane (POSS) as a support matrix. This work presents a study on the immobilization of catalase on functionalized POSS structure to enhance its stability and performance. The synthesized Cat@Glu@OAPOSS was extensively characterized by using Fourier transform infrared spectroscopy (FTIR), Powder X-ray diffraction (PXRD), and Field emission electron microscopy (FESEM) to confirm its immobilization and structural integrity. It was observed that 24.8 mg g⁻¹ of catalase was immobilized on the POSS matrix. The developed composite, i.e., Cat@Glu@OAPOSS, was efficiently used for the evaluation of catalytic activity in the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H₂O₂). By altering the parameters such as pH, Cat@Glu@OAPOSS dosage, TMB, and H₂O₂ concentration were optimized for TMB oxidation. Enzyme kinetics were examined using the Michaelis-Menten plot and the Lineweaver-Burk plot; the findings show that the enzyme-substrate affinity and reaction rate are favorable, with the value of K_m and V_max as 1.05 mM and 0.98 mM sec⁻¹, respectively. The innovative utilization of modified POSS as an immobilization scaffold provides improved enzyme stability and reusability.

In this paper, a novel temperature-sensitive dual self-healing magnetic polyurethane has been developed based on the Diels–Alder (DA) reaction between acrylamide and furfural and the Schiff base reaction between furfural and polyether amino. Unlike other self-healing polymers that require external force, this polymer relies only on magnetic force to close the cross-section, allowing remote control of the polymer without touching it. The polyurethane has a stable structural composition and excellent mechanical properties, exhibiting different properties over a narrow temperature range. By grafting functional groups on the surface of NdFeB to improve the dispersion of NdFeB, the problem of non-uniform dispersion due to NdFeB deposition and aggregation during the polyurethane curing process has been partially solved. The thermal stability of the polymers was determined using a differential scanning calorimeter. The results show that magnetic actuation can make the cross-section tighter than external force. The surface modification of NdFeB effectively improves the aggregation problem of NdFeB and improves the mechanical properties of polyurethane to a certain extent, which has a wide range of applications. Several simple modular magnetic drive models are constructed, which provide examples for more complex magnetic drive models in the future.

The incorporation of nanofillers into biodegradable polymers is an effective approach to improve the physical properties and mechanical performance for various practical applications. In particular, the interfacial microstructure between the polymer and nanofillers plays a critical role in determining the macroscopic properties of the resulting polymer nanocomposite. In this work, we report carbon nanotube (CNT) induced interfacial transcrystallization of poly(L-lactic acid) (PLLA) in the single-fiber composite. The dynamic process of PLLA transcrystallization around the single CNT fiber is investigated under isothermal crystallization in the temperature range from 124°C to 136°C using in situ polarized optical microscopy. Transcrystallization kinetics are analyzed based on polymer heterogeneous nucleation and crystallization theories. The interfacial free energy difference parameter (Δσ/σ = 0.057) and the fold surface free energy (σ_e = 5.82 × 10⁻² J/m²) are calculated to assess the nucleation ability and crystallization barrier, respectively. Atomic force microscope (AFM) analysis reveals radially aligned edge-on lamellar crystals adjacent to the CNT fiber. Alternative transformation from the edge-on lamellar orientation to a flat-on orientation results in a banded transcrystalline texture. A proposed mechanism is presented that lamellar twisting during the crystal growth is attributed to the banded transcrystals.

This study presents a one-pot emulsion polymerization that combines step-growth process of methylene-bis(4-cyclohexylisocyanate) (HMDI) and polyether polyol (EP-330N) to form polyurethane (PU) and chain growth radical polymerization of methyl methacrylate (MMA) and crosslinker ethylene dimethacrylate (EDMA) to produce crosslinked poly(methyl methacrylate) (PMMA). The as-prepared interpenetrating PU-PMMA hybrid latexes have features of tailored cross-linking densities (gel content as high as 49.8%, controlled by the molar ratio of ─NCO/─OH, namely R-value), yielding colloidally stable particles (90–110 nm) with a spherical morphology. FTIR and Soxhlet extraction are employed to characterize the successful synthesis of hybrid particles. As-proof of application, the PU-PMMA particles have been used as a toughening modifier of poly(vinyl chloride) resin (PVC). The impact strength of PVC blends increases from 2.6 to 4.6 kJ/m² with 0–10 phr PU-PMMA addition. These results demonstrate that the one-pot emulsion polymerization integrating radical and step-growth mechanisms could be considered as a straightforward, green emulsification method to synthesize interpenetrating hybrid particles with tunable properties.

Lignin, an underutilized aromatic biopolymer from agricultural waste, is promising for functional hydrogels. However, the complex composition, molecular heterogeneity, and low active site accessibility of lignin severely restrict its practical applications. Traditional lignin extraction methods result in over 80% cleavage of β-O-4 bonds and a significant loss of phenolic hydroxyl groups. In this study, four different molecular weight lignins (F1-F4) were obtained from cotton stalks via γ-valerolactone pretreatment. The molecular weights of F1-F4 were 5203, 2926, 1956, and 938g/mol, with total phenolic hydroxyl contents of 0.03, 0.09, 0.27, and 0.54 mmol/g, respectively. Compared with hydrogels of the high-molecular-weight lignin (F1), the low-molecular-weight lignin-based hydrogel (F4) exhibited 3.32-fold enhanced elasticity, 4.23-fold improved conductivity, and 1.52-fold higher antibacterial activity. Notably, the γ-valerolactone pretreatment preserved β-O-4 bonds more effectively, while increasing the pore size by 1.57-fold. These results indicated that the low-molecular-weight lignin with high phenolic hydroxyl content conferred the hydrogel with significantly enhanced elasticity, conductivity, and antibacterial activity, making it highly promising for applications in drug delivery, wound healing, and wearable biosensors. This work demonstrates a green route to valorize agricultural lignin into high-performance hydrogel materials.