2 research outputs found
Multivalent grafting of hyperbranched oligo- and polyglycerols shielding rough membranes to mediate hemocompatibility
Hemocompatible materials are needed for internal and extracorporeal biomedical
applications, which should be realizable by reducing protein and thrombocyte
adhesion to such materials. Polyethers have been demonstrated to be highly
efficient in this respect on smooth surfaces. Here, we investigate the
grafting of oligo- and polyglycerols to rough poly(ether imide) membranes as a
polymer relevant to biomedical applications and show the reduction of protein
and thrombocyte adhesion as well as thrombocyte activation. It could be
demonstrated that, by performing surface grafting with oligo- and
polyglycerols of relatively high polydispersity (>1.5) and several reactive
groups for surface anchoring, full surface shielding can be reached, which
leads to reduced protein adsorption of albumin and fibrinogen. In addition,
adherent thrombocytes were not activated. This could be clearly shown by
immunostaining adherent proteins and analyzing the thrombocyte covered area.
The presented work provides an important strategy for the development of
application relevant hemocompatible 3D structured materials
An ellipsometric approach towards the description of inhomogeneous polymer-based Langmuir layers
The applicability of nulling-based ellipsometric mapping as a complementary method next to Brewster angle microscopy (BAM) and imaging ellipsometry (IE) is presented for the characterization of ultrathin films at the air–water interface. First, the methodology is demonstrated for a vertically nonmoving Langmuir layer of star-shaped, 4-arm poly(ω-pentadecalactone) (PPDL-D4). Using nulling-based ellipsometric mapping, PPDL-D4-based inhomogeneously structured morphologies with a vertical dimension in the lower nm range could be mapped. In addition to the identification of these structures, the differentiation between a monolayer and bare water was possible. Second, the potential and limitations of this method were verified by applying it to more versatile Langmuir layers of telechelic poly[(rac-lactide)-co-glycolide]-diol (PLGA). All ellipsometric maps were converted into thickness maps by introduction of the refractive index that was derived from independent ellipsometric experiments, and the result was additionally evaluated in terms of the root mean square roughness, Rq. Thereby, a three-dimensional view into the layers was enabled and morphological inhomogeneity could be quantified