Bioinert surface to protein adsorption with higher generation of dendrimer SAMs

Bio-inert Properties of TEG Modified Dendrimer Interface

The bioinert interfaces that prevent adhesion of proteins and cells are important for biomaterial applications. In order to design a bioinert interface, the immobilization of an appropriate functional group and the control of molecular density is required. Dendrimer was modified with triethylene glycol (TEG) to display a dense brush structure. TEG with different density and terminal groups were immobilized with a dendrimer template and thiol terminated molecules. The inhibitory effect on protein and bacteria binding was investigated. The physical property of the interface was measured by QCM-admittance to clarify the factor of the bioinert property.

Regenerative biosensor for use with biotinylated bait molecules

Label-free biosensors are ideally suited for the quantitative analysis of specific interactions among biomolecules or of biomolecules with drugs, as well as for quantitation of diagnostic markers in biofluids. In contrast to the label-dependent methods, a new assay for a particular prey molecule can be set up within few minutes by immobilizing the corresponding bait molecule on the sensor surface, using one of the common immobilization procedures. Unfortunately, the extensive application of label-free biosensors is still hampered by the fact that the immobilization of the bait molecule is usually irreversible; for that reason, a new chip (which is expensive) is required for every successful or futile attempt. Here, we present a general method for the switchable immobilization of biotinylated bait molecules on a new desthiobiotin surface, using wild-type streptavidin as a robust bridge between the chip and the biotinylated bait. The immobilization of the bait is very stable, so that many cycles of prey injection and subsequent prey removal can be carried out. For the latter, common reagents like HCl, Na₂CO₃, glycine buffer, or SDS are employed. When desired, however, streptavidin plus the biotinylated bait can be completely removed by 3min injections of biotin, guanidinium thiocyanate, pepsin, and SDS, which makes it possible to immobilize new biotinylated bait. The number of in situ regeneration cycles is unlimited during the lifetime of the chip (2-3 weeks). One chip can easily be shared by many users with unrelated tasks (as is typical in academics), or used for the fully automated screening of many different interactions (for example in pharmaceutical research). In comparison to other regenerative chips, the new chip surface has much wider applicability and all of its structural and functional parameters have been disclosed.

The effects of nanomaterials on blood coagulation in hemostasis and thrombosis

The blood coagulation balance in the organism is achieved by the interaction of the blood platelets (PLTs) with the plasma coagulation system (PCS) and the vascular endothelial cells. In healthy organism, these systems prevent thrombosis and, in events of vascular damage, enable blood clotting to stop bleeding. The dysregulation of hemostasis may cause serious thrombotic and/or hemorrhagic pathologies. Numerous engineered nanomaterials are being investigated for biomedical purposes and are unavoidably exposed to the blood. Also, nanomaterials may access vascular system after occupational, environmental, or other types of exposure. Thus, it is essential to evaluate the effects of engineered nanomaterials on hemostasis. This review focuses on investigations of nanomaterial interactions with the blood components involved in blood coagulation: the PCS and PLTs. Particular emphases include the pathophysiology of effects of nanomaterials on the PCS, including the kallikrein-kinin system, and on PLTs. Methods for investigating these interactions are briefly described, and a review of the most important studies on the interactions of nanomaterials with plasma coagulation and platelets is provided. WIREs Nanomed Nanobiotechnol 2017, 9:e1448. doi: 10.1002/wnan.1448 For further resources related to this article, please visit the WIREs website.

Functionalization of surfaces with branched polymers

This review summarizes recent developments in the field of surfaces functionalized with branched polymers, including the fabrication methods, morphologies, properties and applications.

Effect of molecular architecture on single polymer adhesion

Several applications require strong noncovalent adhesion of polymers to substrates. Graft and branched polymers have proven superior to linear polymers, but the molecular mechanism is still unclear. Here, this question is addressed on the single molecule level with an atomic force microscopy (AFM) based method. It is determined how the presence of side chains and their molecular architecture influence the adhesion and the mobility of polymers on solid substrates. Surprisingly, the adhesion of mobile polymers cannot significantly be improved by side chains or their architecture. Only for immobile polymers a significantly higher maximum rupture force for graft, bottle-brush, and branched polymers compared to linear chains is measured. Our results suggest that a combination of polymer architecture and strong molecular bonds is necessary to increase the polymer-surface contact area. An increased contact area together with intrachain cohesion (e.g., by entanglements) leads to improved polymer adhesion. These findings may prove useful for the design of stable polymer coatings.

The influence of nanostructured materials on biointerfacial interactions

Control over biointerfacial interactions in vitro and in vivo is the key to many biomedical applications: from cell culture and diagnostic tools to drug delivery, biomaterials and regenerative medicine. The increasing use of nanostructured materials is placing a greater demand on improving our understanding of how these new materials influence biointerfacial interactions, including protein adsorption and subsequent cellular responses. A range of nanoscale material properties influence these interactions, and material toxicity. The ability to manipulate both material nanochemistry and nanotopography remains challenging in its own right, however, a more in-depth knowledge of the subsequent biological responses to these new materials must occur simultaneously if they are ever to be affective in the clinic. We highlight some of the key technologies used for fabrication of nanostructured materials, examine how nanostructured materials influence the behavior of proteins and cells at surfaces and provide details of important analytical techniques used in this context.