Assessment and characterization of degradation effect for the varied degrees of ultra-violet radiation onto the collagen-bonded polypropylene non-woven fabric surfaces

Exposure to ultra-violet (UV)-C radiation is a frequently used method to pr event bacteria from invasion of blood-contact biomedical products. Potentia l damage induced by UV radiation to collagen is of concern due to the decay of bioactivity, considerably correlated with structural alterations. Our c urrent investigation studies the collagen-bonded non-woven polypropylene (P P) fabric surface. In this experiment, antenna-coupling microwave plasma is utilized to activate PP fabric and then the sample is grafted with acrylic acid (AAc). Type III collagen is immobilized by using water soluble 1-ethy l-3-(3-dimethylaminopropy]) carbodiimide as coupling agent. The collagen-bo nded samples with sample temperature ca. 4 degreesC are then exposed to UV- 254nm radiation for different time intervals. By using fourier- transformed infrared with attenuated total reflection (FTIR-ATR) and XPS (X-ray photoe lectron spectroscopy), we examine the chemical structures of samples with d ifferent treatments. Coomassie brilliant blue G250 method is utilized to qu antify the immobilized collagen on the PP fabric surfaces. Blood-clotting e ffects are evaluated by activated partial thromboplastin time, thrombin tim e, and fibrinogen concentration tests. By means of cell counter and scannin g electron microscopy we count red blood cells and platelets adhesion in th e modified porous matrix. Our experimental results have demonstrated that w ith pAAc-grafting of ca. 173 mug cm(-2), and immobilized collagen of 80.5 /- 4.7 mug cm(-2) for human plasma incubated samples of various intervals o f UV-254 nm radiation, fibrinogen concentration decreases in human plasma, while platelets and red blood cells adhesions increase before UV radiation. However, the required time for thrombination shows significant change for UV radiation exposure of less than 20 h (alpha = 0.05). The decay of bioact ivity for the UV-irradiated, collagen-bonded surfaces is thus evaluated. Su rface analyses indicate that the decrease of R-COOH (derivated from grafted -pAAc or de-carboxylation of collagen), amides. degradation (broken-NH), an d phenylalanine scission (terminated by -OH, tyrosine formation) may gradua lly damage collagen by increasing the intervals of UV radiation. These effe cts considerably influence the bioactivity of the collagenbonded fabric. Th e XPS measurements of C Is core levels at 288.4 eV (O = C-NH) and at 289.1 eV (O = C-O) illustrate significant decreases of intensity after radiation time ca. 44 h. It is clear that UV-254 nm radiation exposure for ca. 20 h h as the potential impact to moderate the bioactivities. of collagen and ther efore act as a vital factor to accelerate biodegradation. (C) 2001 Elsevier Science Ltd. All rights reserved.