Selective albumin-binding surfaces modified with a thrombin-inhibiting peptide

Abstract

a b s t r a c tBlood-contacting medical devices have been associated with severe clinical complications, such as thrombus formation, triggered by the activation of the coagulation cascade due to the adsorption of certain plasma proteins on the surface of biomaterials. Hence, the coating of such surfaces with antithrombotic agents has been used to increase biomaterial haemocompatibility. Biomaterial-induced clotting may also be decreased by albumin adsorption from blood plasma in a selective and reversible way, since this protein is not involved in the coagulation cascade. In this context, this paper reports that the immobilization of the thrombin inhibitor D-Phe-Pro-D-Arg-D-Thr-CONH 2 (fPrt) onto nanostructured surfaces induces selective and reversible adsorption of albumin, delaying the clotting time when compared to peptide-free surfaces. fPrt, synthesized with two glycine residues attached to the N-terminus (GGfPrt), was covalently immobilized onto self-assembled monolayers (SAMs) having different ratios of carboxylate-hexa(ethylene glycol)-and tri(ethylene glycol)-terminated thiols (EG6-COOH/EG3) that were specifically designed to control GGfPrt orientation, exposure and density at the molecular level. In solution, GGfPrt was able to inactivate the enzymatic activity of thrombin and to delay plasma clotting time in a concentration-dependent way. After surface immobilization, and independently of its concentration, GGfPrt lost its selectivity to thrombin and its capacity to inhibit thrombin enzymatic activity against the chromogenic substrate n-p-tosyl-Gly-Pro-Arg-p-nitroanilide. Nevertheless, surfaces with low concentrations of GGfPrt could delay the capacity of adsorbed thrombin to cleave fibrinogen. In contrast, GGfPrt immobilized in high concentrations was found to induce the procoagulant activity of the adsorbed thrombin. However, all surfaces containing GGfPrt have a plasma clotting time similar to the negative control (empty polystyrene wells), showing resistance to coagulation, which is explained by its capacity to adsorb albumin in a selective and reversible way. This work opens new perspectives to the improvement of the haemocompatibility of blood-contacting medical devices.

Self-Assembled Monolayers for Dental Implants

“…Concerning antiadhesive surfaces, SAMs presenting oligomers of ethylene glycol, commonly prepared using the alkanethiols HS(CH 2 ) 11 (OCH 2 CH 2 ) n OH (EG n , n = 3–7 or OEG), resist the adsorption of several proteins and the adhesion of cells [ 83 – 91 ]. OEG-SAMs on gold present low adsorption of several blood proteins and blood cell adhesion as well as adhesion of the gastrointestinal bacterial species H. pylori as reported by us [ 86 , 92 – 94 ]. This antiadhesive effect has been explained through theoretical and experimental research [ 95 – 99 ], indicating that water penetrates into the (EG) n OH layers of the SAMs forming a stable interfacial water layer, which prevents the direct contact between the underlying surface and the proteins and/cells.…”

A Recombinant Fusion Construct between Human Serum Albumin and NTPDase CD39 Allows Anti-Inflammatory and Anti-Thrombotic Coating of Medical Devices

“…Human serum albumin (HSA) is widely used in the medical industry for coating of stents and tubings [ 26 , 27 ]. Being a highly abundant protein in the blood, HSA has been shown to have anti-thrombotic properties and corrosion resistance based on its electrostatic and hydrophilic properties [ 18 , 26 , 28 ].…”

“…Human serum albumin (HSA) is widely used in the medical industry for coating of stents and tubings [ 26 , 27 ]. Being a highly abundant protein in the blood, HSA has been shown to have anti-thrombotic properties and corrosion resistance based on its electrostatic and hydrophilic properties [ 18 , 26 , 28 ]. Additionally, HSA adsorbs easily on surfaces, prevents endothelial apoptosis, provides antioxidant protection and also inhibits platelet activation and aggregation [ 27 , 29 , 30 ].…”

“…Therefore, albumin has played a central role in many drug delivery systems [ 31 ]. HSA coating has also been applied to various biomaterials, including titanium (Ti), stainless steel and nanoparticles [ 26 , 28 , 32 , 33 ]. For example, dopamine-modified albumin coating showed an attenuated immune and inflammatory response on xenogeneic grafts [ 34 ].…”

Structure-Based Design, Synthesis and Evaluation of Novel Peptidic Inhibitors of Thrombin-Induced Activation of Platelets Aggregation

“…Moreover, other collaborators in the field developed biomaterials with enhanced haemocompatibility containing our lead peptidic DTI [D-Phe-Pro-D-Arg-D-Thr-CONH2] (fPrt) [6]. The research proved that the immobilization of the thrombin inhibitor (fPrt) onto nanostructured surfaces induces selective and reversible adsorption of albumin, delaying the clotting time when compared to peptide-free surfaces [5]. To further improve the potency and selectivity of the peptidic DTI and assess their future potential as scaffolds for developing biomaterials with improved haemocompatibility for the blood-contacting medical devices, we performed a structure-based drug design (SBDD) and structure-activity relationship (SAR) evaluation of novel peptidic DTI by …”