Surface modification has been proved to be one of the effective strategies for enhancing the properties of graphene sheets. When a non-covalent modification method is appropriately designed, novel opportunities for better performance of graphene nanosheets can be expected since this strategy can tailor the properties of graphene while its natural structure is retained. This paper introduces a simple route to prepare a highly biocompatible, stable and conductive graphene hybrid modified by poly-L-lysine (PLL) for biosensors using the non-covalent strategy. Results show that PLL adopts a random conformation with the nonpolar parts exposed to outside since its side chains are positively charged under neutral conditions. This conformation allows the strong adhesion of PLL to graphene surface via the hydrophobic interaction between butyl chains of PLL and graphene surface, cation-p interaction of protonated amine groups on PLL with the p electrons in graphene, and electrostatic interaction between the protonated amine groups on PLL and the negatively charged carboxyl groups remaining on graphene. All these interactions make the resultant PLL-G hybrid stable and dispersible in aqueous solutions. The resultant hybrid is then used to construct high performance biosensors. As demonstration, hemoglobin (Hb) carrying negative charges can be easily immobilized on the hybrid via electrostatic interactions with the positively charged lysine side chains of PLL modified on graphene

Objectives:To compare laparoscopic extraperitoneal colostomy with transperitoneal colostomy for construction of a permanent stoma by measuring the incidence of parastomal hernia, and other postoperative complications related to colostomy.Methods:The meta-analysis was carried out in the General Surgery Department of the Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China in 2014. A literature search of Medline, EMBASE, Cochrane database, and the Chinese Biomedical Literature Database (CBM) from the years 1990 to 2014 was performed. The literature searches were carried out using medical subject headings and free-text words: extraperitoneal colostomy, transperitoneal colostomy, laparoscopic extraperitoneal colostomy, rectal cancer, laparoscopic abdominoperineal resection, parastomal hernia, permanent stoma, and colostomy-related complications. Two different reviewers carried out the search and evaluated studies independently.Results:One randomized controlled trial and 6 retrospective studies were included. A total of 378 patients (209 extraperitoneal colostomy and 169 transperitoneal colostomy) were identified. Our analysis showed that there was a significantly lower rate of parastomal hernia (odds ratio 0.10; 95% confidence interval 0.03-0.29, p<0.0001) in the extraperitoneal colostomy group. However, the other stoma-related complications were not significantly different between the 2 groups.Conclusion:Colostomy construction via the extraperitoneal route using a laparoscopic approach can largely reduce the incidence of parastomal hernia. Laparoscopic permanent sigmoid stoma creation through the extraperitoneal route should be the first choice after laparoscopic abdominoperineal resection.