A new ultralow fouling surface for the analysis of human plasma samples with surface plasmon resonance.

Surface plasmon resonance (SPR) has been widely used to detect a variety of biomolecular systems, but only a small fraction of applications report on the analysis of patients' samples. A critical barrier to the full implementation of SPR technology in molecular diagnostics currently exists for its potential application to analyze blood plasma or serum samples. Such capability is mostly hindered by the non-specific adsorption of interfering species present in the biological sample at the functional interface of the biosensor, often referred to as fouling. Suitable polymeric layers having a thickness ranging from 15 and about 70 nm are usually deposited on the active surface of biosensors to introduce antifouling properties. A similar approach is not fully adequate for SPR detection where the exponential decay of the evanescent plasmonic field limits the thickness of the layer beyond the SPR metallic sensor surface for which a sensitive detection can be obtained. Here, a triethylene glycol (PEG(3))-pentrimer carboxybetaine system is proposed to fabricate a new surface coating bearing excellent antifouling properties with a thickness of less than 2 nm, thus compatible with sensitive SPR detection. The high variability of experimental conditions described in the literature for the quantitative assessment of the antifouling performances of surface layers moved us to compare the superior antifouling capacity of the new pentrimeric system with that of 4-aminophenylphosphorylcholine, PEG-carboxybetaine and sulfobetaine-modified surface layers, respectively, using undiluted and diluted pooled human plasma samples. The use of the new coating for the immunologic SPRI biosensing of human arginase 1 in plasma is also presented.

Photocrosslinkable polysaccharide hydrogel composites based on dextran or pullulan-amylose blends with cytokines for a human co-culture model of human osteoblasts and endothelial cells.

Although a large body of research has been devoted to biomaterial development for bone tissue engineering and related medical disciplines in the last few years, novel and optimized materials especially for bone fractures of critical sizes demand continued development. In this respect, polysaccharide-based hydrogels demonstrate beneficial properties and fulfill the main requirements for a bone tissue scaffold as they are hydrophilic, biocompatible, and biodegradable. The aim of the present study was the development of a natural polysaccharide-based scaffold material that can integrate with the host tissue and support bone regeneration. For this purpose, we prepared and investigated two polymer hydrogel composites of photocrosslinkable derivatives of either pure dextran or a mixture of amylose and pullulan with varying composition. In order to increase their biological activity the swollen hydrogel matrices were compounded with stromal derived growth factor (SDF-1) and bone morphogenic protein (BMP-2). As skeletal development is known to depend on angiogenesis, these hydrogel systems were subjected to mono- and co-culture models of human primary osteoblasts (hOBs) with human endothelial cells (HUVEC - as precursors for blood vessel development). The effect of cytokines on hydrogel-dependent cell behavior was analyzed in the presence and absence of the growth factors SDF-1 and BMP-2. Both the employed cell types grew on all cytokine-modified hydrogel composites, which was assessed by optical microscopy and proliferation assays. Migration assays indicated enhanced HUVEC migration under the influence of SDF-1 and real-time PCR demonstrated an enhanced expression of cell-specific markers for growth factor-modified hydrogels, thus demonstrating their functional bioactivity. Our results demonstrate the fundamental potential of such multi-component polysaccharide hydrogel composites as biomaterials for bone regeneration.