title: Molecularly designed surfaces for blood deheparinization using an immobilized heparin-binding peptide.
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-(35)S-heparin. Therefore, this study could give a good contribution for the design of blood deheparinization devices.
authors.affiliation: Instituto de Engenharia Biomédica, Divisão de Biomateriais, Universidade do Porto, Rua do Campo Alegre, 823, 4150-180, Porto, Portugal. cmartins@ineb.up.pt
authors.forename: M Cristina L
authors.initials: MC
authors.lastname: Martins
authors.forename: Scott A
authors.initials: SA
authors.lastname: Curtin
authors.forename: Sidónio C
authors.initials: SC
authors.lastname: Freitas
authors.forename: Pedro
authors.initials: P
authors.lastname: Salgueiro
authors.forename: Buddy D
authors.initials: BD
authors.lastname: Ratner
authors.forename: Mário A
authors.initials: MA
authors.lastname: Barbosa
mesh_terms: D000327:Adsorption; D019855:Ethylene Glycol; D006493:Heparin / Q000009:adverse effects / Q000097:blood* / Q000302:isolation & purification*; D006801:Humans; D007930:Leucine; D008239:Lysine; D008722:Methods; D049329:Nanostructures / Q000737:chemistry / Q000627:therapeutic use*; D010455:Peptides / Q000737:chemistry / Q000627:therapeutic use*; D011485:Protein Binding; D006435:Renal Dialysis / Q000009:adverse effects*; D013499:Surface Properties
chemical_list: D010455:Peptides; D006493:Heparin; D019855:Ethylene Glycol; D007930:Leucine; D008239:Lysine