



@article {3285,
	title = {Selective albumin-binding surfaces modified with a thrombin-inhibiting peptide},
	journal = {Acta Biomaterialia},
	volume = {10},
	year = {2014},
	note = {Export Date: 21 November 2014},
	month = {2014},
	pages = {1227 - 1237},
	abstract = {Blood-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. {\textcopyright} 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.},
	keywords = {Albumin, Blood compatibility, Clotting, Surface modification, Thrombin},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84895067841\&partnerID=40\&md5=8486186625f8f4f1cbc538bb3e34dd82},
	author = {Freitas, S.C. and Maia, S. and Figueiredo, A.C. and Gomes, P. and Pereira, P.J.B. and Barbosa, M.A. and Martins, M.C.L.}
}
@booklet {2190,
	title = {Bioengineered surfaces to improve the blood compatibility of biomaterials through direct thrombin inactivation},
	howpublished = {Acta BiomaterialiaActa Biomater.},
	year = {2012},
	note = {Export Date: 21 November 2012Source: ScopusArticle in Pressdoi: 10.1016/j.actbio.2012.07.020Language of Original Document: EnglishCorrespondence Address: Martins, M.C.L.; INEB - Instituto de Engenharia Biom{\'e}dica, Universidade do Porto, Rua do Campo Alegre 823, 415email: cmartins@ineb.up.pt},
	month = {2012///},
	abstract = {Thrombus formation, due to thrombin generation, is a major problem affecting blood-contacting medical devices. This work aimed to develop a new strategy to improve the hemocompatibility of such devices by the immobilization of a naturally occurring thrombin inhibitor into a nanostructured surface. Boophilin, a direct thrombin inhibitor from the cattle tick Rhipicephalus microplus, was produced as a recombinant protein in Pichia pastoris. Boophilin was biotinylated and immobilized on biotin-terminated self-assembled monolayers (SAM) via neutravidin. In order to maintain its proteinase inhibitory capacity after surface immobilization, boophilin was biotinylated after the formation of a boophilin-thrombin complex to minimize the biotinylation of the residues involved in thrombin-boophilin interaction. The extent of boophilin biotinylation was determined using matrix-assisted laser desorption/ionization-time of flight/time of flight mass spectrometry. Boophilin immobilization and thrombin adsorption were quantified using quartz crystal microbalance with dissipation. Thrombin competitive adsorption from human serum was assessed using                        125I-thrombin. Thrombin inhibition and plasma clotting time were determined using spectrophotometric techniques. Boophilin-coated SAM were able to promote thrombin adsorption in a selective way, inhibiting most of its activity and delaying plasma coagulation in comparison with boophilin-free surfaces, demonstrating boophilin{\textquoteright}s potential to improve the hemocompatibility of biomaterials used in the production of blood-contacting devices. {\textcopyright} 2012 Acta Materialia Inc.
},
	keywords = {Coagulation, Hemocompatibility, Protein adsorption, Surface functionalization, Thrombin},
	isbn = {17427061 (ISSN)},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84865246462\&partnerID=40\&md5=278b2e7d1427a6032eba9ecbd01c3872},
	author = {Freitas, S.C. and Cereija, T.B. and Figueiredo, A.C. and Os{\'o}rio, H. and Pereira, P.J.B. and Barbosa, M.A. and Martins, M.C.L.}
}
@article {2281,
	title = {Adhesion of human leukocytes on mixtures of hydroxyl- and methyl-terminated self-assembled monolayers: Effect of blood protein adsorption},
	journal = {Journal of Biomedical Materials Research - Part AJ. Biomed. Mater. Res. Part A},
	volume = {93},
	year = {2010},
	note = {Cited By (since 1996): 4Export Date: 21 November 2012Source: ScopusCODEN: JBMRCdoi: 10.1002/jbm.a.32480PubMed ID: 19484768Language of Original Document: EnglishCorrespondence Address: Barbosa, J. N.; Divis{\~a}o de Biomateriais, INEB-Instituto de Engenharia Biom{\'e}dica, Universidade do Porto, Porto 4150-180, Portugal; email: judite@ineb.up.ptChemicals/CAS: Blood Proteins; Gold, 7440-57-5; Hydroxyl Radical, 3352-57-6References: Brodbeck, W.G., Nakayama, Y., Matsuda, T., Colton, E., Ziats, N.P., Anderson, J.M., Biomaterial surface chemistry dictates adherent monocyte/macrophage cytokine expression in vitro (2002) Cytokine, 18, pp. 311-319;Kao, W.Y.J., Evaluation of leukocyte adhesion on polyurethanes: The effects of shear stress and blood proteins (2000) Biomaterials, 21, pp. 2295-2303; 
Tegoulia, V.A., Cooper, S.L., Leukocyte adhesion on model surfaces under flow: Effects of surface chemistry, protein adsorption, and shear rate (2000) J Biomed Mater Res, 50, pp. 291-301; 
Nimeri, G., Ohman, L., Elwing, H., Wettero, J., Bengtsson, T., The influence of plasma proteins and platelets on oxygen radical production and F-actin distribution in neutrophils adhering to polymer surfaces (2002) Biomaterials, 23, pp. 1785-1795; 
Wettero, J., Bengtsson, T., Tengvall, P., C1q-independent activation of neutrophils by immunoglobulin M-coated surfaces (2001) J Biomed Mater Res, 57, pp. 550-558; 
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Rodrigues, S.N., Goncalves, I.C., Martins, M.C.L., Barbosa, M.A., Ratner, B.D., Fibrinogen adsorption, platelet adhesion and activation on mixed hydroxyl-/methyl-terminated self-assembled monolayers (2006) Biomaterials, 27, pp. 5357-5367; 
Martins, M.C.L., Ratner, B.D., Barbosa, M.A., Protein adsorption on mixtures of hydroxyl- and methylterminated alkanethiols self-assembled monolavers (2003) J Biomed Mater Res, 67 A, pp. 158-171. , Part A; 
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Barbosa, J.N., Barbosa, M.A., Aguas, A.P., Adhesion of human leukocytes to biomaterials: An in vitro study using alkanethiolate monolayers with different chemically functionalized surfaces (2003) J Biomed Mater Res, 65 A, pp. 429-434. , Part A; 
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Barbosa, J.N., Barbosa, M.A., Aguas, A.P., Inflammatory cell recruitment and adhesion to methyl-terminated selfassembled monolayers: Effect of implantation time (2005) Microsc Res Tech, 66, pp. 37-42; 
Barbosa, J.N., Madureira, P., Barbosa, M.A., Aguas, A.P., The attraction of Mac-1(+) phagocytes during acute inflammation by methyl-coated self-assembled monolayers (2005) Biomaterials, 26, pp. 3021-3027
},
	month = {2010///},
	pages = {12 - 19},
	abstract = {The adhesion of human leukocytes to nanostructured surfaces with different chemical properties and the effect of protein adsorption were investigated. Selfassembled monolayers (SAMs) prepared with mixtures of methyl- and hydroxyl-terminated alkanethiols in different percentages on gold were used. The surfaces were preimmersed in distinct protein solutions (human serum albumin, human fibrinogen, and autologous plasma). Adherent leukocytes were analyzed both by light and SEM. SAMs submitted to pre-immersion in plasma presented higher numbers of adherent leukocytes in the pure OH-terminated SAM, whereas methyl-terminated surfaces accounted for the lowest number of adherent cells. We observed a general increase in the number of adherent human leukocytes as the percentage of OH groups on the surface of the SAMs increased for all the pre-immersion conditions investigated. The number of adherent human leukocytes is highly influenced by the pre-immersion conditions used, and this observation is particularly relevant in the case of the methyl-terminated SAMs. The results obtained demonstrate that surface chemistry has a major influence in leukocyte adhesion to biomaterials, and that pre-immersion in protein solutions has a determinant effect in leukocyte adhesion. {\textcopyright} 2009 Wiley Periodicals, Inc.},
	keywords = {Adherent cells, Adhesion, Adsorption, Alkanethiols, article, Biological materials, biomaterial, Blood protein adsorption, Blood Proteins, cell adhesion, Cell Count, Chemical properties, gold, human, human cell, Human leukocytes, Human serum albumins, Humans, hydroxyl group, Hydroxyl Radical, Hydroxyl-terminated, immersion, Inflammatory response, leukocyte adherence, Leukocyte adhesion, Leukocytes, Nanostructured materials, Nanostructured surface, Nanostructured surfaces, OH group, Protein adsorption, protein blood level, Protein solution, Proteins, Sams, Scanning electron microscopy, Self assembled monolayers, Self-assembled monolayers, SEM, Surface chemistry, Surface Properties},
	isbn = {15493296 (ISSN)},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-77649225392\&partnerID=40\&md5=0b35403e1b98581c557435b6cf7a8286},
	author = {Barbosa, J.N. and Martins, M.C.L. and Freitas, S.C. and Gon{\c c}alves, I.C. and {\'A}guas, A.P. and Barbosa, M.A.}
}
@article {2279,
	title = {The effect of immobilization of thrombin inhibitors onto self-assembled monolayers on the adsorption and activity of thrombin},
	journal = {BiomaterialsBiomaterials},
	volume = {31},
	year = {2010},
	note = {Cited By (since 1996): 7Export Date: 21 November 2012Source: ScopusCODEN: BIMADdoi: 10.1016/j.biomaterials.2010.01.097PubMed ID: 20153046Language of Original Document: EnglishCorrespondence Address: Martins, M.C.L.; INEB - Instituto de Engenharia Biom{\'e}dica, Divis{\~a}o de Biomateriais, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal; email: cmartins@ineb.up.ptChemicals/CAS: thrombin, 9002-04-4; Albumins; Gold, 7440-57-5; Immobilized Proteins; Iodine Radioisotopes; Peptides; Solutions; Thrombin, 3.4.21.5References: Gorbet, M.B., Sefton, M.V., Biomaterial-associated thrombosis: roles of coagulation factors, complement, platelets and leukocytes (2004) Biomaterials, 25 (26), pp. 5681-5703;Ratner, B.D., Hoffman, A.F., Schoen, F.J., Lemons, J.L., (2004) Biomaterials science - an introduction to materials in medicine. 2nd ed., , Elsevier Academic Press, San Diego, CA, USA; 
Bode, W., Structure and interaction modes of thrombin (2006) Blood Cells Mol Dis, 36 (2), pp. 122-130; 
Huntington, J.A., Molecular recognition mechanisms of thrombin (2005) J Thromb Haemost, 3 (8), pp. 1861-1872; 
Schwienhorst, A., Direct thrombin inhibitors - a survey of recent developments (2006) Cell Mol Life Sci, 63 (23), pp. 2773-2791; 
Tseng, P.-Y., Rele, S.S., Sun, X.-L., Chaikof, E.L., Membrane-mimetic films containing thrombomodulin and heparin inhibit tissue factor-induced thrombin generation in a flow model (2006) Biomaterials, 27 (12), pp. 2637-2650; 
Sperling, C., Salchert, K., Streller, U., Werner, C., Covalently immobilized thrombomodulin inhibits coagulation and complement activation of artificial surfaces in vitro (2004) Biomaterials, 25 (21), pp. 5101-5113; 
Lin, J.C., Tseng, S.M., Surface characterization and platelet adhesion studies on polyethylene surface with hirudin immobilization (2001) J Mater Sci Mater Med, 12 (9), pp. 827-832; 
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Weitz, J.I., Crowther, M., Direct thrombin inhibitors (2002) Thromb Res, 106 (3), pp. V275-V284; 
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},
	month = {2010///},
	pages = {3772 - 3780},
	abstract = {Thrombus formation is the major problem associated with biomaterials for blood contact medical devices. The immobilization of inhibitors to thrombin, a serine protease that plays a central role on the coagulation system, on the surface of biomaterials should be a good strategy to avoid blood clotting and increase their hemocompatibility. The aim of this work is the design of a nanostructured surface with capacity to adsorb and inactivate thrombin. The pentapeptide sequence d-Phenylalanine-Proline-Arginine-Proline-Glycine (fPRPG), that was described as a thrombin inhibitor, was immobilized onto tetra(ethylene glycol) terminated self-assembled monolayers (EG4-SAMs). Surface containing different amounts of fPRPG were prepared using different concentrations of N,N'-Carbonyldiimidazole (CDI) during immobilization. The efficiency of fPRPG immobilization was followed using ellipsometry, contact angle measurements, Infrared reflection absorption spectroscopy (IRRAS) and X-ray photoelectron spectroscopy (XPS). Thrombin adsorption was quantified using radiolabelled thrombin and its activity in solution and after adsorption on the developed surfaces was assessed using a chromogenic assay. It was found that, although the immobilization of fPRPG on to EG4-SAMs does not increase its selectivity to thrombin, the activity of the adsorbed thrombin was inhibited in a peptide concentration dependent way. We concluded that SAMs with fPRPG immobilized in high amounts can be used as thrombin-inhibitor surfaces, which is a good step on the development of new surfaces for blood contact devices. {\textcopyright} 2010 Elsevier Ltd. All rights reserved.},
	keywords = {Absorption spectroscopy, Adsorption, adsorption kinetics, Albumins, Amino Acid Sequence, Amino acids, Angle measurement, article, Biomaterials, Blood, Blood clotting, Blood contact, Carbonyldiimidazole, Coagulation, Coagulation system, concentration (parameters), Concentration-dependent, Contact angle, D-phenylalanine, ellipsometry, Ethylene, Ethylene Glycol, ethylene glycol derivative, gold, Hemocompatibility, Humans, imidazole derivative, Immobilized Proteins, Infrared reflection absorption spectroscopy, infrared spectroscopy, Iodine Radioisotopes, isotope labeling, Medical Devices, monolayer culture, nanoanalysis, Nanostructured surface, peptide, Peptide immobilization, Peptides, phenylalanylprolylarginylprolylglycine, Phosphatases, priority journal, Protein adsorption, protein assembly, protein function, protein immobilization, quantitative study, Sams, Self assembled monolayers, Self-assembled monolayers, Serine protease, Solubility, Solutions, Spectroscopy, Fourier Transform Infrared, Surface functionalization, Surface Properties, Tetra, tetra(ethylene glycol), Thrombin, thrombin inhibitor, Thrombin inhibitors, Thrombus formation, unclassified drug, X ray photoelectron spectroscopy},
	isbn = {01429612 (ISSN)},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-77649271932\&partnerID=40\&md5=f7180daf23d326319cf6d8dbf0eac77c},
	author = {Freitas, S.C. and Barbosa, M.A. and Martins, M.C.L.}
}
@article {2325,
	title = {Molecularly designed surfaces for blood deheparinization using an immobilized heparin-binding peptide},
	journal = {Journal of Biomedical Materials Research - Part AJ. Biomed. Mater. Res. Part A},
	volume = {88},
	year = {2009},
	note = {Cited By (since 1996): 12Export Date: 21 November 2012Source: ScopusCODEN: JBMRCdoi: 10.1002/jbm.a.31849PubMed ID: 18286636Language of Original Document: EnglishCorrespondence Address: Martins, M. C. L.; INEB - Instituto de Engenharia Biom{\'e}dica, Divis{\~a}o de Biomaterials, Universidade do Porto, Rua do Campo Alegre, 823, 4150-180, Porto, Portugal; email: cmartins@ineb.up.ptChemicals/CAS: carbonyldiimidazole, 530-62-1; heparin, 37187-54-5, 8057-48-5, 8065-01-8, 9005-48-5; imidazole, 1467-16-9, 288-32-4; leucine, 61-90-5, 7005-03-0; lysine, 56-87-1, 6899-06-5, 70-54-2; tetraethylene glycol, 112-60-7; Ethylene Glycol, 107-21-1; Heparin, 9005-49-6; Leucine, 61-90-5; Lysine, 56-87-1; PeptidesReferences: Dailey J. Blood. Ipswich, MA, USA: Medical Consulting Group; 1998Section, V., Chronic intermittent haemodialysis and prevention of clotting in the extracorporal system (2002) Nephrol Dialysis Transplant, 17, pp. 63-71;Zhang, Y.H., Singh, V.K., Yang, V.C., Novel approach for optimizing the capacity and efficacy of a protamine filter for clinical extracorporeal heparin removal (1998) Asaio J, 44, pp. M368-M373; 
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},
	month = {2009///},
	pages = {162 - 173},
	abstract = {Systemic heparinization, used during haemodialysis to prevent blood clotting on the extracorporeal circuit, leads to a high incidence of hemorrhagic complications. The adverse reactions associated with heparin neutralization using protamine sulphate justify the development of an alternative system for blood deheparinization. The main objective of this work is to design nanostructured surfaces with the capacity to bind heparin from blood in a selective way. A heparin-binding polypeptide, composed of L-lysine and L-leucine (pKL), was synthesized and immobilized, in different concentrations, onto self-assembled monolayers (SAMs) terminated with tetra(ethylene-glycol) (EG4 SAMs). Immobilization was performed using a fixed concentration of pKL after surface activation to different degrees using a range of CDI (N,N'-carbonyldiimidazole) concentrations. Results demonstrated that the presence of pKL increases heparin adsorption to EG4-SAMs, independently of the pKL concentration and the way of immobilization (adsorption or covalent bound). Selectivity towards heparin was successfully achieved on SAMs with low concentrations of immobilized pKL (9-17\% of pKL). Surfaces were characterized using ellipsometry, contact angle measurements, Fourier transform infrared reflection absorption spectroscopy (IRAS), atomic force microscopy, and X-ray photoelectron spectroscopy. Heparin adsorption was assessed using IRAS and N-sulphonate-                        35S-heparin. Therefore, this study could give a good contribution for the design of blood deheparinization devices. {\textcopyright} 2008 Wiley Periodicals, Inc.
},
	keywords = {Absorption spectroscopy, Adsorption, Alternative systems, Amines, Amino acids, Angle measurement, article, Atomic force microscopy, Atomic forces, Atomic spectroscopy, Binding peptides, Blood, Blood clotting, Carbonyl diimidazole, Carbonyldiimidazole, Contact angle, deheparinization, device, Dialysis, Electron energy levels, ellipsometry, Ethylene, Ethylene Glycol, Fourier Transform Infrared, Fourier transforms, Glycols, Haemodialysis, heparin, heparin binding protein, Heparinization, High incidences, Humans, imidazole, immobilization, infrared spectroscopy, leucine, Low concentrations, lysine, Methods, Missile bases, Monolayers, nanomaterial, Nanostructured surfaces, Nanostructures, Peptide immobilization, Peptides, Photoelectron spectroscopy, Polysaccharides, Protein adsorption, protein binding, Renal Dialysis, Self assembled monolayers, Self-assembled monolayers, Sulphate, Surface activations, Surface functionalization, Surface Properties, surface property, tetraethylene glycol, unclassified drug, X ray photoelectron spectroscopy, X-ray photoelectron spectroscopies},
	isbn = {15493296 (ISSN)},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-57449118932\&partnerID=40\&md5=8f442ccbde0273f4ed4e04024a75fd37},
	author = {Martins, M.C.L. and Curtin, S.A. and Freitas, S.C. and Salgueiro, P. and Ratner, B.D. and Barbosa, M.A.}
}
