BACKGROUND:Alginate-chitosan microcapsule can improve the mechanical property of sodium alginate hydrogels. How to obtain the ideal sodium alginate-chitosan microcapsule and the prospect for application of the microcapsule system is the key to this study.
OBJECTIVE:To investigate the preparation method and formation mechanism of alginate-chitosan microcapsules, to analyze several important factors affecting the strength of the microcapsule membrane, and to explore the prospects of alginate-chitosan microcapsules in immobilized celltechnology, in tissue engineering and as a drug carrier.
METHODS:The first author searched PubMed, Elsevier ScienceDirect, CNKI and Wanfang database (1987/2013) to retrieve literatures about the preparation method, formation mechanism and application prospect of alginate-chitosan microcapsules.
RESULTS AND CONCLUSION:Sodium alginate hydrogels have many advantages in drug release and tissue engineering, but its application is limited by gel dissolution phenomena and deficiencies in its mechanical properties. Chitosan-alginate microcapsules make up for the deficiency of sodium alginate hydrogels by electrostatic interactions to form polyelectrolyte complexes. By control ing the nature of the chitosan solution--the molecular weight of chitosan, pH and concentration of chitosan solution, we can prepare the microcapsules with high film strength. Alginate-chitosan microcapsules have shown broad application prospects in immobilization technology, drug release and tissue engineering.

Objective To investigate the influence factors of mortality among human immunodeficiency virus (HIV)-infected children under highly active antiretroviral therapy (HAART).Methods Retrospective cohort study of 652 children initiated HAART from 2005 to 2014 was conducted,and enrolled patients were followed-up until December,2015.Survival data was analyzed using Kaplan-Meier method and Cox regression model was used to identify independent predictors of mortality among these children on HARRT.Chi-square test and Fisher's exact test were used for comparison between groups.Results Overall,26 of the children died over a follow-up period of 3 116.24 child-years,with a mortality rate of 0.83 per 100 child-years.Twelve (46％)of deaths occurred during the first six months after starting HAART.Cox regression analysis of variables showed that the World Health Organization (WHO) clinical stages Ⅲ/Ⅳ (hazard rate [HR] =10.717,95％confidence interal [95％ CI]:4.189-4.749,P =0.000),baseline hemoglobin ＜ 80 g/L (HR =14.768,95 ％ CI:5.721-38.125,P =0.000),tuberculosis co-infection (HR =4.794,95％ CI:2.105-10.918,P =0.000),baseline CD4+T lymphocyte ＜ 50 cells/μL (HR =4.219,95％ CI:1.524-11.680,P =0.006),weight-for-age z-score ＜-2 (HR =2.983,95 ％ CI:1.094-8.135,P =0.033) were independently associated with death,whereas the age ＜ 7 year-old at HAART initiation was protectire (HR =0.293,95％ CI:0.126-0.684,P =0.005).Conclusions The mortality of children receiving HAART is strongly associated with WHO stages Ⅲ/Ⅳ,hemoglobin ＜ 80 g/L,weight-for-age z-score ＜-2,tuberculosis co-infection and older age at treatment.