Daniela Maria Porfírio Rodrigues

29 Aug 2012

Daniela Maria Porfírio Rodrigues was born in Coimbra, Portugal on January 11th, 1984. She joined Coimbra Technical Institute (IPC), College of Agriculture (ESAC), Food Engineering Department in 2002 and graduated from the Department in 2007 with B.S. degree. After graduation, she started her career in research field as Research Fellow in the project MARE FDR 27 – Innovation in Cod fish Industry: Development of a new fermented product and brine reutilization, at College of Agriculture. While working she started pursuing her master degree, again in food engineering program at ESAC-IPC in the fall semester of 2008. During her masters graduation, and after her research project ended, she worked also as a trainer in the areas of quality control in microbiology; quality management; microbiological analysis of water; food chemistry; HACCP systems; nutrition and dietetics. In April of 2010 she graduates with Master degree and continues working as a trainer. In September of 2011 she returns to work as a Reseaserch Fellow at the Department of Chemical Engineering, University of Coimbra in the project PTDC/CTM-POL/112289/2009 NanoBioCats. Her current interests are polymers electrospinning, surface modification, enzyme immobilization and biocathalysis.

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Abstract


Electrospun PCL nanomembranes: polymer blends and surface modifications – physical characterization and comparison

Tailor-made micro/nanofibers have been widely used for several applications due to their high surface area to volume ratio, high porosity and nanofiber size, which can be controlled by adjusting the solution properties and the process parameters [1]. The aim of this work was to develop a nanomembrane by electrospinning with improved performance for use in biocatalytic processes. Electrospinning has recently been widely explored as a method to fabricate nanofibers for various applications, including filtration media, fibre-reinforced plastics and fibres loaded with catalysts and chemical indicators [2]. Poly(epsilon-caprolactone) (PCL), a semicrystalline aliphatic polyester, was submitted to electrospinning and collected as a mat. After modification, it will be used for the immobilization of enzymes in order to create a system which could be applied in biotechnological processes. Additionally, PCL has been suggested for various applications such as drug delivery and tissue-engineered scaffolds [3].  To get a more active membrane for enzyme immobilization, different approaches were attempted: i) blends of PCL with different types of poly(lactic acid) (PLA) (with  different ramification degrees); ii) PCL surface modifications with plasma and UV radiation in order to create radicals on the surface of the mat which were used for the copolymerization of polyacids, and iii) copolymerization of methacrylic acid (MAA) and 2-hydroxyethyl methacrylate (HEMA) onto PCL.

The electrospun micro/nanofibers prepared from a PCL solution, alone or in a mixture with monomers and polymers, modified or not by UV radiation or plasma, were analyzed by SEM in order to attain a full analysis of morphology, porosity, fiber dimensions and surface properties. The results show that PLC with PLA generates thinner fibers with fewer beads at 8% (w/w)  polymer concentration in the electrospinning solution, with a flow rate of 1.5 mL/h. In fact, the average micro/nanofiber diameters of the pure PCL fibers and PCL/PLA fibers were 200 ± 50 and 100 ± 30 nm, respectively.  It was also observed that the mats obtained by plasma modification appear to be destroyed in its fiber structure; there was a disruption in fiber connection. Mechanical properties were evaluated by uniaxial extension, including tensile strength, Young’s modulus and elongation. DSC was used to study the thermal properties of the electrospun membranes, namely the crystallization and melting behavior. Contact angle measurements were done to evaluate the mats hydrophobicity. The chemical composition of the mat was evaluated by FTIR.

[1] Yabin Zhu, Changyou Gao, Jiacong Shen, “Surface modification of polycaprolactone with poly(methacrylic acid)and gelatin covalent immobilization for promoting its cytocompatibility” , Biomaterials 23 (2002) 4889–4895.

[2] Hyeon Yoon and GeunHyung Kim, “Micro/Nanofibrous Scaffolds Electrospun from PCL and Small Intestinal Submucosa”, Journal of Biomaterials Science 21 (2010) 553–562.

[3] Fang Jian, Niu HaiTao, Lin Tong, Wang XunGai, “Applications of electrospun nanofibers”, Chinese Science Bulletin  53 (2008) 2265-2286.