Bioactive albumin functionalized polylactic acid membranes for improved biocompatibility

Biocompatibility is a major challenge for successful application of many biomaterials. In this study the ability to coat chemically and enzymatically activated poly(L-lactic acid) (PLA) membranes with heat denatured human serum albumin to improve biocompatibility was investigated. PLA membranes hydrolyzed with NaOH or cutinase and then treated with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, hydrochloride (EDAC) as a heterobifunctional cross-linker promoted the coupling single bondCOOH groups on PLA membranes and single bondNH2 groups of heat denatured human serum albumin. This resulted in increased hydrophilicity (lowest water contact angles of 43° and 35°) and highest antioxidant activity (quenching of 79 μM and 115 μM tetramethylazobisquinone (TMAMQ) for NaOH and cutinase pretreated membranes, respectively). FTIR analysis of modified PLA membranes showed new peaks attributed to human serum albumin (amide bond, NH2 and side chain stretching) appearing within 3600–3000 cm−1 and 1700–1500 cm−1 (Fig. 3). MTT studies also showed that osteoblasts-like and MC-3T3-E1 cells viability increased 2.4 times as compared to untreated PLA membranes. The study therefore shows that this strategy of modifying the surfaces of PLA polymers could significantly improve biocompatibility.

Identifying clones in functional programs for refactoring

Clone detection is well established for imperative programs. It works mostly on the statement level and therefore is ill-suited for func- tional programs, whose main constituents are expressions and types. In this paper we introduce clone detection for functional programs using a new intermediate program representation, dubbed Functional Control Tree. We extend clone detection to the identi cation of non-trivial func- tional program clones based on the recursion patterns from the so-called Bird-Meertens formalism