Ultralow Protein Adsorption Hemocompatible Biomaterials

异物表面上的凝血仍然是许多器械（包括心血管旁路、支架、导管和葡萄糖传感器）临床应用的主要限制。在许多情况下，血小板是生物材料表面上血液凝固的引发剂。 我们实验室最近的研究已经确定了消除血小板粘附的定量设计标准，即需要将纤维蛋白原吸附降低到非常低的水平（低于5 ng/cm 2），远低于大多数材料的吸附水平。 我们已经制备的射频等离子体沉积的四甘醇二甲醚材料通常可以满足这一标准，但这是否会导致我们寻求的完全血液相容的生物材料仍有待证明。 我们还必须确定可以持续实现超低纤维蛋白原摄取，并且材料在这方面是稳定的。 因此，有必要对甘醇二甲醚的制备工艺进行完善，并对其血液相容性进行评价。 该提案的具体目标如下：1.将优化四甘醇二甲醚等离子体处理条件，以实现涂层均匀性，耐用性和超低蛋白质吸收，并将制造一种新的反应器来处理较长管的内表面。 将测试关于紧密结合的水在导致甘醇二甲醚涂层不结垢中的作用的假设。 将评价用于产生等离子体沉积的PEG样表面的两种新单体。 2.将血浆中的纤维蛋白原吸附与一系列四甘醇二甲醚的ESCA和TOF-SIMS表面化学数据进行比较，以确定导致超低纤维蛋白原摄取的条件。 四甘醇二甲醚系列将在变化的反应器条件下制备，这将引起表面化学的变化，并因此允许我们测试以下假设：实现超低结垢必须满足的标准是高的、相对于非醚碳的优化的醚碳含量和防止分层。 还将测量对纤连蛋白、玻连蛋白、von Willebrand因子和IgG污染的抗性。 将用表面等离子体共振和二维凝胶电泳表征对从血浆中摄取所有蛋白质的抗性。 3.将使用体外和体内方法表征血液相互作用。 将在一系列甘醇二甲醚涂层材料预暴露于血浆或纤维蛋白原后，测量其体外血小板粘附和促凝血活性。 通过测量与四甘醇二甲醚接触的抗凝血浆中的凝血时间和凝血酶活性，评估非血小板介导的凝血事件的作用。 将使用激光栓子检测表征非粘附接触对血小板活化和聚集的影响。 通过测量凝血的急性期和稳态指标，在装有管状四甘醇二甲醚离体分流管的犬中评估显示超低纤维蛋白原和血小板摄取的材料的体内血液相容性。

Blood clotting on foreign surfaces remains a major limitation in the clinical application of many devices, including cardiovascular bypass, stents, catheters, and glucose sensors. In many situations, platelets are the initiator of blood clotting on the biomaterial surface. Recent studies in our lab have identified a quantitative design criterion to eliminate platelet adhesion, namely the need to reduce fibrinogen adsorption to very low levels (less than 5 ng/cm2), far below that which occurs on most materials. Radio frequency plasma deposited tetraglyme materials we have made can often meet this criteria, but it remains to be shown whether this results in the perfectly blood compatible biomaterial that we seek. We also must establish that ultra-low fibrinogen uptake can be achieved consistently and that the materials are stable in this regard. Therefore, a series of studies to perfect the glyme technology and evaluate its blood compatibility is proposed. The specific aims of the proposal are as follows: 1. Tetraglyme plasma treatment conditions will be optimized to achieve coating uniformity, durability and ultra low protein uptake and a new reactor to treat the inside surfaces of longer tubes will be made. A hypothesis about the role of tightly bound water in causing non-fouling of glyme coatings will be tested. Two new monomers for producing plasma deposited PEG- like surfaces will be evaluated. 2. Fibrinogen adsorption from plasma will be compared to ESCA and TOF-SIMS surface chemical data for a series of tetraglymes to establish the conditions that result in ultra-low fibrinogen uptake. The tetraglyme series will be made under varying reactor conditions which will cause variations in surface chemistry, and thus allow us to test the hypothesis that the criteria that must be met to achieve ultra- low fouling are high, optimized ether carbon content relative to non-ether carbon and prevention of delamination. Resistance to fouling by fibronectin, vitronectin, von Willebrand factor, and IgG will also be measured. Resistance to uptake of all proteins from plasma will be characterized with surface plasmon resonance and by two dimensional gel electrophoresis. 3. Blood interactions will be characterized using both in vitro and in vivo methodology. In vitro platelet adhesion and procoagulant activation on a series of glyme coated materials will be measured after their pre-exposure to blood plasma or fibrinogen. The role of non-platelet mediated clotting events will be assessed by measuring clotting times and clotting enzyme activity in recalcified plasma in contact with the tetraglymes. The effect of non-adhesive encounters on platelet activation and aggregation will be characterized using laser emboli detection. In vivo blood compatibility of materials exhibiting ultralow fibrinogen and platelet uptake will be assessed in dogs with tubular tetraglyme ex vivo shunts by measuring both acute phase and steady state indicators of clotting.