



@article {3273,
	title = {Characterization of hLF1-11 immobilization onto chitosan ultrathin films, and its effects on antimicrobial activity},
	journal = {Acta Biomaterialia},
	volume = {10},
	year = {2014},
	note = {Cited By (since 1996):1Export Date: 21 November 2014},
	month = {2014},
	pages = {3513 - 3521},
	abstract = {hLF1-11 (GRRRRSVQWCA) is an antimicrobial peptide (AMP) with high activity against methicillin-resistant Staphylococcus aureus (MRSA), the most prevalent species in implant-associated infection. In this work, the effect of the surface immobilization on hLF1-11 antimicrobial activity was studied. Immobilization was performed onto chitosan thin films as a model for an implant coating due to its reported osteogenic and antibacterial properties. Chitosan thin films were produced by spin-coating on gold surfaces. hLF1-11 was immobilized onto these films by its C-terminal cysteine in an orientation that exposes the antimicrobial activity-related arginine-rich portion of the peptide. Two levels of exposure (with and without a polyethylene glycol (PEG) spacer) were analyzed. Covalent immobilization was further compared with the AMP physical adsorption onto chitosan films. Surfaces were characterized using ellipsometry, contact angle measurements, atomic force microscopy, infrared and X-ray photoelectron spectroscopies and using a fluorimetric assay for hLF1-11 quantification. Surface antimicrobial activity was assessed through surface adhesion and viability assays using an MRSA (S. aureus ATCC 33591). The incorporation of hLF1-11 increased significantly bacterial adhesion to chitosan films. However, the presence of hLF1-11, namely when immobilized through a PEG spacer, decreased the viability of adherent bacteria with regard to the control surface. These results demonstrated that hLF1-11 after covalent immobilization by its cysteine can maintain activity, particularly if a spacer is applied. However, further studies, exploring the opposite orientation or the same C-terminal orientation, but non-cysteine related, can help to clarify the potential of the hLF1-11 immobilization strategy. {\textcopyright} 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.},
	keywords = {Antimicrobial peptides (AMP), Bacterial adhesion, chitosan, Surface characterization, Surface immobilization},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84903724424\&partnerID=40\&md5=e8009cd480b49c37a991753cd145cf34},
	author = {Costa, F. and Maia, S. and Gomes, J. and Gomes, P. and Martins, M.C.L.}
}
@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.}
}
