Exposure to ultra-violet (UV)-C radiation is a frequently used method to prevent bacteria from invasion of blood-contact biomedical products. Potential damage induced by UV radiation to collagen is of concern due to the decay of bioactivity, considerably correlated with structural alterations. Current investigation indicates to the collagen-immobilized non-woven polypropylene (PP) fabrics with sample temperature ca. 4 °C; the samples are then exposed to UV-254 nm radiation for different time intervals. Using Fourier-Transformed Infrared with Attenuated Total Reflection (FTIR-ATR) and XPS (X-ray Photoelectron Spectroscopy), we examine the chemical structures of samples with different treatments. Blood-clotting effects on the modified samples are assessed by activated partial thromboplastin time, thrombin time, and fibrinogen concentration tests. By means of cell counter and Scanning Electron Microscopy we count red blood cells and platelets adhesion in the modified porous matrix. Applying standard plate count for bacteria tests, E. coli, Bacillus stearothermophilus, Staph. aureus, P. aeruginosa, and Candida albieans are applied. For human plasma incubated samples of various intervals of UV-254 nm radiation, fibrinogen concentration decreases in human plasma, while platelets and red blood cells adhesions increase before UV radiation. The required time for thrombination shows significant change for UV exposure of less than 20 hrs (α = 0.05). Surface analyses indicate that the decrease of R-COOH (derivated from grafted-pAAc or decarboxylation of collagen), amides degradation (broken–NH), and phenylalanine scission (terminated by −OH, tyrosine formation) may gradually damage collagen by increasing the intervals of UV radiation. The XPS measurements of C 1s core levels at 288.1 eV (O=C-NH) and at 289.3 eV (O=C-O) illustrate significant decreases of intensity after radiation time ca. 44 hrs. It is clear that UV-254 nm radiation exposure for ca. 20 hrs has the potential impact to moderate the bioactivities of collagen and therefore act as a vital factor to accelerate bio-degradation. Bacteria test also supports that around 20 hrs of UV radiation, no bacteria clone formation is found on the immobilized collagen. However, the relation between eventual bioactivity of immobilized collagen after UV radiation and the capability of bacteria proliferation should be measured.
Leakage of Potassium from Red Blood Cells following Gamma Ray Irradiation in the Presence of Dipyridamole, Trolox, Human Plasma or Mannitol
