Effect of filler content on morphology and physical-chemical characteristics of poly(vinylidene fluoride)/NaY-zeolite filled membranes

Poly(vinylidene fluoride) electrospun membranes have been prepared with different NaY zeolite contents up to 32%wt. Inclusion of zeolites induces an increase of average fiber size from ~200 nm in the pure polymer up to ~500 nm in the composite with 16%wt zeolite content. For higher filler contents, a wider distribution of fibers occurs leading to a broader size distributions between the previous fiber size values. Hydrophobicity of the membranes increases from ~115º water contact angle to ~128º with the addition of the filler and is independent on filler content, indicating a wrapping of the zeolite by the polymer. The water contact angle further increases with fiber alignment up to ~137º. Electrospun membranes are formed with ~80 % of the polymer crystalline phase in the electroactive  phase, independently on the electrospinning processing conditions or filler content. Viability of MC3T3-E1 cells on the composite membranes after 72 h of cell culture indicates the suitability of the membranes for tissue engineering applications.

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.

Legalidade do Júri do Doutoramento

Qualquer coincidência com a realidade é pura coincidência, ciência. Chegou-nos aos ouvidos por voz credível que haveria quem no Minho defendesse, e passamos a citar, qualquer coisa como: os professores dos institutos politécnicos e os professores de universidades de baixa reputação não deverão fazer parte de júris para provas de doutoramento em determinada Universidade…. Se isto é verdade – além da difamação que pode gerar responsabilidade judicial e civil para os seus autores (quem te avisa, teu amigo é!) -, salvo o devido respeito e amizade, é violador da legislação que, no Estado de Direito, regula a constituição de júris para provas de doutoramento. Se dúvidas existirem, veja-se o art. 34º do DL nº 115/2013, de 7/8 § Any coincidence with reality is purely coincidental, science. We reached our ears by credible voice that there would be anyone in the Minho defend, and we quote, something like: teachers of polytechnics and teachers of low-reputation universities should not be part of juries for PhD exams in certain University .... If this is true - in addition to the defamation that can generate judicial and civil liability for their authors (who warns you, your friend is!) - Unless due respect and friendship, is in breach of legislation, the rule of law, regulates the constitution of juries for doctoral exams. If doubts exist, see art. 34 of DL No. 115/2013, 7/8.