In vitro and in vivo investigation of chitosan/silk fibroin injectable interpenetrating network hydrogel with microspheres for cartilage regeneration.

Articular cartilage is an avascular and almost acellular tissue with limited self-regenerating capabilities. Although injectable hydrogels have garnered a lot of attention as a promising treatment, a biocompatible hydrogel with adequate mechanical properties is yet to be created. In this study, an interpenetrating network hydrogel comprised of chitosan and silk fibroin was created through electrostatic and hydrophobic bonds, respectively. The polymeric network of the scaffold combined an effective microenvironment for cell activity with enhanced mechanical properties to address the current issues in cartilage scaffolds. Furthermore, microspheres (MS) were utilized for a controlled release of methylprednisolone acetate (MPA), around ~75 % after 35 days. The proposed scaffolds demonstrated great mechanical stability with ~0.047 MPa compressive moduli and ~145 kPa compressive strength. Moreover, the degradation rate of the samples (~45 % after 35 days) was optimized to match neo-cartilage formation. Furthermore, the use of natural biomaterials yielded good biocompatibility with ~76 % chondrocyte viability after 7 days. According to gross observation after 12 weeks the defect site of the treated groups was filled with minimally discernible boundary. These results were confirmed by histopathology assays were the treated groups showed higher chondrocyte count and collagen type II expression.

Novel size-based design of spiral microfluidic devices with elliptic configurations and trapezoidal cross-section for ultra-fast isolation of circulating tumor cells.

Investigation and analysis of circulating tumor cells (CTCs) have been valuable resources for detecting and diagnosing cancer in its early stages. Recently, enumeration and separation of CTCs via microfluidic devices have attracted significant attention due to their low cost and easy setup. In this study, novel microfluidic devices based on size-dependent cell-sorting with a trapezoidal cross-section and elliptic spiral configurations were proposed to reach label-free, ultra-fast CTCs enrichment. Firstly, the possibility and quality of separation in the devices were evaluated via a numerical simulation. Subsequently, these devices were fabricated to investigate the effects of the altering curvature and the trapezoidal cross-section on the isolation of CTCs from the peripheral blood sample at varying flow rates ranging from 0.5 mL/min to 3.5 mL/min. The experimental results indicated that the flow rate of 2.5 mL/min provided the optimal separation efficiency in the proposed devices, which was in fine agreement with the numerical analysis results. In this experiment, the purity values of CTCs between 88% and 90% were achieved, which is an indicator of the high capability of the proposed devices for the isolation and enrichment of CTCs. This strategy is hoped to overcome the limitations of classical affinity-based CTC separation approaches in the future.