Development of a bioactive silk fibroin bilayer scaffold for wound healing and scar inhibition.

In cases of deep skin defects, spontaneous tissue regeneration and excessive collagen deposition lead to hyperplastic scars. Conventional remedial action after scar formation is limited with a high recurrence rate. In this study, we designed a new artificial skin bilayer using silk fibroin nanofibers films (SNF) as the epidermis, and silk fibroin (SF) / hyaluronic acid (HA) scaffold as the dermal layer. The regenerated SF film was used as a binder to form a functional SNF-SF-HA bilayer scaffold. The bilayer scaffold showed high porosity, hydrophilicity, and strength, and retained its shape over 30 days in PBS. In vitro, human umbilical vein endothelial cells were seeded into the bilayer scaffold and showed superior cell viability. In vivo analyses using the rabbit ear hypertrophic scar (HS) model indicated that the bilayer scaffold not only supported the reconstruction of new tissue, but also inhibited scar formation. The scaffold possibly achieved scar inhabitation by reducing wound contraction, weakening inflammatory reactions, and regulating collagen deposition and type conversion, which was partly observed through the downregulation of type I collagen, transforming growth factor-ß, and α-smooth muscle actin. This study describes a new strategy to expand the application of silk-based biomaterials for the treatment of hyperplastic skin scars.

Optimized Design of Solid-Liquid Dual-Impeller Mixing Systems for Enhanced Efficiency.

Flow interferences occur in the dual-impeller stirred tank between paddles as well as between paddles and baffles and the tank wall, leading to inefficient utilization of the stirring energy. To address this issue, this study investigates the flow characteristics within the mixing tank using Euler-Euler numerical simulation and the particle image velocimetry (PIV) experimental method. The three-dimensional nonconstant flow characteristics are analyzed to optimize the critical stirrer geometry. By employing the Sobol method, an approximate model is established for sensitivity analysis to identify key parameters affecting the solid-liquid dual-impeller stirred tank's performance. Numerical simulations demonstrate that the optimized stirred tank exhibits a significantly improved solid-liquid suspension capacity and considerably reduces flow losses near the wall and baffle areas. Under the designated conditions, the cloud height is increased by 8.7%, and power consumption is reduced by 15.6% compared to the prototype. PIV tests performed on the stirred tank before and after optimization confirmed the reliability of the obtained optimization results. The primary objective of this study is to enhance mixing efficiency and homogeneity in solid-liquid mixing tanks while concurrently minimizing energy consumption and cost. These results validate the feasibility of employing a multiobjective optimal design approach that combines the RBF agent model with the Sobol method. The findings offer valuable insights for the design of similar mixing tanks.

Advances in Skin Wound and Scar Repair by Polymer Scaffolds.

Scars, as the result of abnormal wound-healing response after skin injury, may lead to loss of aesthetics and physical dysfunction. Current clinical strategies, such as surgical excision, laser treatment, and drug application, provide late remedies for scarring, yet it is difficult to eliminate scars. In this review, the functions, roles of multiple polymer scaffolds in wound healing and scar inhibition are explored. Polysaccharide and protein scaffolds, an analog of extracellular matrix, act as templates for cell adhesion and migration, differentiation to facilitate wound reconstruction and limit scarring. Stem cell-seeded scaffolds and growth factors-loaded scaffolds offer significant bioactive substances to improve the wound healing process. Special emphasis is placed on scaffolds that continuously release oxygen, which greatly accelerates the vascularization process and ensures graft survival, providing convincing theoretical support and great promise for scarless healing.

Application of an ultrahigh-performance liquid chromatography coupled to quadrupole-orbitrap high-resolution mass spectrometry for the rapid screening, identification and quantification of illegal adulterated glucocorticoids in herbal medicines.

In this work, the ultrahigh-performance liquid chromatography quadrupole orbitrap high resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) was applied to the rapid screening, identification and quantification of the illegal adulterated glucocorticoids in herbal medicines. The mass spectrometer was operated in positive ion mode and Full MS/dd-MS2 (data-dependent MS2) mode, where selected ions were subjected to a dd-MS2 scan with given fragmentation energy following a Full MS scan. The application of 70 000 FWHM mass resolution and narrow mass windows (5ppm) effectively improve the selectivity of the method, and a single injection was sufficient to perform the simultaneous screening and identification/quantification of 14 glucocorticoids in 15min. The method validation including selectivity, sensitivity, calibration curve, accuracy, precision, recovery, matrix effect and stability were evaluated. The results of all analytes showed excellent linear relationship while all coefficient of determination (r2) were>0.9990 over wide concentration ranges (e.g., 5-1000ng/mL for hydrocortisone butyrate, r2=1.0000). The recoveries were in the range of 86.1-102.7%, while the matrix effects ranged from 95.8%-105.8%. Accuracies and precisions were performed. The intra- and inter-day accuracies ranged from 90.6% to 108.9%, while the intra- and inter-day precisions were in the range of 0.5% to 8.5%. Finally, the established method was employed to detect illegal adulterated glucocorticoids in herbal medicines. It will provide more reliable technical basis for the drug quality supervision department and ensure public health.