Huizhen Zheng,Meng Gao,Ying Ren,Ruyun Lou,Hongguo Xie,Weiting Yu,Xiudong Liu,Xiaojun Ma
The surface properties of implanted materials or devices play critical roles in modulating cell behavior. However, the surface properties usually affect cell behaviors synergetically so that it is still difficult to separately investigate the influence of a single property on cell behavior in practical applications. In this study, alginate–chitosan (AC) microcapsules with a dense or loose gel structure were fabricated to understand the effect of gel structure on cell behavior. Cells preferentially adhered and spread on the loose gel structure microcapsules rather than on the dense ones. The two types of microcapsules exhibited nearly identical surface positive charges, roughness, stiffness, and hydrophilicity; thus, the result suggested that the gel structure was the principal factor affecting cell behavior. X-ray photoelectron spectroscopy analyses demonstrated that the overall percentage of positively charged amino groups was similar on both microcapsules. The different gel structures led to different states and distributions of the positively charged amino groups of chitosan, so we conclude that the loose gel structure facilitated greater cell adhesion and spreading mainly because more protonated amino groups remained unbound and exposed on the surface of these microcapsules.
A simple microfluidic strategy is proposed for the controllable preparation of calcium alginate/chitosan (CaA/CS) microcapsules with ultrathin shells for peroxidase immobilization. In this study, the composite microcapsules are composed of CaA and CS, which are beneficial to improve the stability of CaA microcapsules, and are generated using a two-stage capillary microfluidic device. The inner layer of the composite capsule shells is ionically cross-linked CaA, and the outer layer is covalently cross-linked CS. Moreover, the Fe3O4 magnetic nanoparticles are added to facilitate the recovery and reuse of the composite microcapsules. The morphology, permeability, encapsulation efficiency, enzyme activity, and reusability of CaA/CS microcapsules are investigated. The overall thickness of the double-layered shell is about 346 nm. Meanwhile, the microcapsules have good molecular selective permeability, excellent encapsulation performance, stable enzyme activity, and good stability for reusability. The composite microcapsules retained above 80% of residual activity after six recycle uses. The developed novel strategy for fabricating peroxidase-immobilized CaA/CS microcapsules with ultrathin shells is of great potential value for enzyme immobilization applications.
Jin Cao,Jin Cheng,Siyu Xi,Xueyong Qi,Song Shen,Yanru Ge
Targeted delivery of bioactive compounds such as proteins to the colon has numerous advantages for the therapeutic treatment of inflammatory bowel disease . The present study sought to fabricate alginate/chitosan microcapsules containing IL-1Ra (Alg/Chi/IL-1Ra MC) via a single-step electrospraying method. Two important factors of efficacy were measured—the pH-responsiveness of the microcapsule and the in-vitro drug release profile. The DSS-induced colitis mouse model was used to evaluate the therapeutic effect of the Alg/Chi/IL-1Ra microcapsules, with results showing the protective effect of the Alg/Chi microcapsules for the passage of IL-1Ra through the harsh environment of the upper gastrointestinal tract . This effect was owing to the pH-sensitive response of the microcapsule, which allowed the targeted release of IL-1Ra in the colon. DAI evaluation, colon length, colon tissue morphology, histologic damage scores and relative protein concentrations (MPO, TNF-α and IL-1β) demonstrated that the Alg/Chi/IL-1Ra microcapsules alleviated DSS-induced colitis in mice. The present study thus demonstrates a practical means of oral delivery of proteins, in-situ colon release, and a promising application of IL-1Ra in the treatment of autoimmune and inflammatory diseases .
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