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The surface of meltblown poly(butylene terephthalate) (PBT) nonwoven was modified by photochemistry using the photolinker O‐succinimidyl 4‐azido‐2,3,5,6‐tetrafluorobenzoate for the introduction of activated ester functions and then coupling of molecular probes or biomolecules. Approximately 4000 pmol of (L)‐4,5‐[3H]‐lysine was fixed per PBT sample (1.13 cm2) and measured by liquid scintillation counting. The method consisted in a two‐step process: (a) coating of the clip (0.05 mg/sample) on the fibrous surface of the PBT followed by UV irradiation (30 min, 254 nm) and (b) coupling of amine‐terminated molecules (10−3 M in phosphate buffer–CH3CN [1/1, v/v], 20 h). Moreover, about 2000 pmol of 3H‐lysine can be immobilized on the PBT surface after UV irradiation (without clip) by aminolysis reactions with the created oxygenated functions. The derivatizations (via the clip and UV irradiation only) were stable after long‐term heating at 100 °C in water or under steam‐sterilization conditions. They induce neither modifications of the nonwoven morphology nor cytotoxicity. This method was applied for the grafting of peptides Gly‐Arg‐Gly‐Asp‐Ser and Gly‐Gly‐Gly‐Gly‐Gly to perform blood filtration experiments and to retain the leukocytes. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

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For clinical indications and according to European standards, a depletion of the leukocytes from whole blood has to be realized before transfusion to a patient. In this study, the surface of a layer of meltblown oxygen-plasma treated polypropylene nonwoven (O(2)-PP), making part of the composition of leukodepletion filters, was modified with bioactive molecules to enhance the adhesion of leukocytes. These synthetic small molecules (called peptidomimetics) mimic the "Leu-Asp-Val" (LDV) tripeptide sequence recognized by the α(4)β(1) integrin, a receptor expressed on leukocytes. Their activity, as ligands of the α(4)β(1) integrin, was confirmed through cell adhesion assays. The peptidomimetics were covalently immobilized on O(2)-PP nonwoven via activation of the hydroxyl- and carboxyl-functions displayed on the polymer surface with trifluoro-triazine reagent, or were simply deposited on the O(2)-PP surface. The treated materials were characterized by X-ray photoelectron spectroscopy, wettability, and morphological analyses, before and after steam sterilization. Experimental filters composed of 10 layers of O(2)-PP nonwovens and a last layer modified with the peptidomimetics were evaluated, using whole blood filtration assays, for their leukodepletion efficiency, the recovery of red cells and platelets and the waste of blood, with an objective to design new filters fulfilling practical and medical criteria.

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