Gradient Polymer Brushes for Tissue Engineering: From 2D to 3D systems

FEBS Workshop

Abstract Booklet

Biological Surfaces and Interfaces

30 June - 05 July 2013

Hotel Eden Roc, Sant Feliu de Guixols, Catalonia, Spain

Chair:

Ralf Richter, CIC biomaGUNE, ES

Co-Chair:

Catherine Picart, Grenoble INP, FR

Vice-Chairs:

Eva-Kathrin Sinner, BOKU, AT;

Contributed Posters

36 FEBS Workshop

“Biological Surfaces and Interfaces” 2013

Poster#53

Gradient polymer brushes for tissue engineering: From 2D to 3D systems.

Michel Klein Gunnewiek1

, E. M. Benetti2

, L. Dos Ramos3

, T van der Horst1

, C. A. Van Blitterswijk4

, L. Moroni4 , G. J. Vancso1,

1

Department of Materials Science and Technology of Polymers, University of Twente, MESA+ Institute for Nanotechnology, P.O. Box 217, 7500 AE Enschede, The Netherlands 2

Laboratory for Surface Science and Technology, ETH Zürich, Dept. of Materials, Wolfgang Pauli Strasse 10, HCI G543, 8093 Zürich, Switzerland 3

Department of Materials Science and Technology of Polymers, University of Twente, MESA+ Institute for Nanotechnology, P.O. Box 217, 7500 AE Enschede, The Netherlands 4Department of Tissue Regeneration, University of Twente, MIRA Institute for

Biomedical Technology and Technical Medicine, P.O. Box 217, 7500 AE Enschede, The Netherlands

With increasing life expectancy, there is increasing demand for finding solutions to restore damaged or diseased tissues and organs. Regenerative medicine holds the promise to create continuous body-part replacements through the combination of cells, biological factors, and scaffolds. However, a better control over cell-material interactions need to be achieved to fabricate better performing and long-lasting products. In particular, it is still critical to control stem cell migration and differentiation into 3D scaffolds. In human bodies stem cell mobilization and differentiation is ruled by physical and chemical gradients. Therefore, to induce cell migration and differentiation, modifying polymer scaffolds with surface gradients is of great interest. One way to obtain surface gradients is by performing surface initiated polymerizations (SIP), e.g. surface initiated Atom Transfer Radical Polymerization (SI-ATRP).In this project, SI-ATRP ZDVXVHGWRJUDIW3RO\ROLJRHWK\OHQHJO\FROPHWKDFU\ODWH32(*0$EUXVKOD\HUVIURPERWK'DQG'SRURXVSRO\ɟ-caprolactone) (PCL) supports. The high density of functionalities on POEGMA grafts assures the subsequent immobilization of protein signals and growth factors. The controlled process involved in SI-ATRP allows variation of brush chain lengths, and grafting densities, additionally enabling the fabrication of gradients of brush structures on PCL surfaces. The so-fabricated supports were applied as scaffolds for human Mesenchymal Stem Cells (hMSCs) adhesion. These pluripotent cells adopted different morphologies as a function of the supports characteristics (e.g. brush length and surface-concentration of coupled proteins). Controlled modification of coating and composition properties on 2D and 3D scaffolds finally allowed directing the behavior of hMSCs. Supported by the MESA+ Institute for Nanotechnology of the University of Twente and by the Technology foundation STW (STW 11135).

Poster#54

Biological accumulation at surfaces: from single to multiple proteins and cell mediation of the protein layer

Folashade O Kuforiji, P. Roach P.

Institute for Science and Technology in Medicine, Keele University, UK

Modern biomaterials are engineered to repair, replace or augment healthy tissue in order to restore function to damaged body parts. Although mechanical properties derived from the material bulk are well established, attention has turned towards the surface of biomaterials in order to more easily integrate these materials into the body. Protein adsorption to surfaces is the first step in biological processes and also plays a vital role in the integration of an implant in the human body. The interaction of proteins on surfaces is important in medical devices coatings, drug delivery, biosensor and the design of a new material. To date, more fundamental understanding is required on the interaction between biological materials such as proteins, cells and nanostructured surfaces. Mass spectrometry has been used to evaluate differences in cellular secretions in relation to a range of surface chemistries. 3T3 fibroblasts were cultured over surfaces presenting OH, COOH, NH2 and CH3 terminal chemistry, on nano-featured surfaces presenting ordered dimensions in the range 10-250 nm. Cells were cultured in serum-free media analysed at varying culture time periods using mass spectrometry (LC-ESI and MALDI).Protein solutions of serum albumin (BSA),fibrinogen (Fg), vitronectin and laminin were used to experimentally evaluate isotherms and assess competitive binding characteristics. BCA and Fluoroprofile assays were used along with specifically fluoro tagged proteins to construct isotherm data. Monodispersed silica spheres of varying sizes(10.5-QP ZHUH SUHSDUHG YLD WKH 6WɰEHU SURFHVV EHLQJ DFLG ZDVKHG DQG IXUWKHU silane modified to present OH, CH3, NH2 and COOH terminal chemistry. Characterisation was carried out via wettability, EM, FTIR and dynamic light scattering. Infrared analysis of surface bound protein was conducted using ATR with Matlab being used for 2D correlation analysis. Mass spectral investigation of culture media highlights differences associated with cell-surface interaction in relation to both chemistry and nano-features. Surface charge and wettability play a major role in determining cell secretion response. Variance is observed at very short incubation times, with no additional variance being observed at longer times. Investigation of adsorbed protein layer composition and structural change of individual proteins supports the hypothesis that cells rapidly respond directly to mediate environment for cell attachment. These are important findings helping to direct the development of surface engineering approaches for advanced materials for the control of biological responses.