Abstract: Objectives To evaluate the effect of virus reduction in plasma using LED white light. Methods Methylene blue was added to plasma at a final concentration of 1 µM. The activity of coagulation factors in plasma and the inactivation effect on Sindbis virus were compared by different treatment methods (10 cm/5 cm spacing, unilateral/bilateral irradiation), different light intensities (30 000 lx, 35 000 lx, 40 000 lx, 45 000 lx, and 50 000 lx) and different time points (10, 20, and 30 min) using LED white light as the light source. Results Increase time of irradiation led to increase of plasma temperature under 50 000 lx light intensity. The extent of increase was found to be greater at 5 cm than at 10 cm spacing, and greater with bilateral than unilateral irradiation. The 5 cm/10 cm spacing and unilateral/bilateral irradiation had no significant differences in their effect on coagulation factor Ⅷ and fibrinogen (FIB) activity. The 10 cm bilateral spacing was selected as the device parameter for photochemical treatment. Plasma was irradiated at intensities of 30 000, 35 000, 40 000, 45 000, and 50 000 lx, respectively. The results showed Sindbis virus in plasma was inactivated after 5 minutes of irradiation at different light intensities, with titer reduction >4 LogTCID₅₀/0.1 mL. Factor Ⅷ and FIB activities were retained at the level of 70% and 60%, respectively after 20 minutes of irradiation. Correlation analysis revealed that there was no correlation between different light intensities and loss of factor Ⅷ activity. However, the effect of light intensities on FIB activity was more pronounced within 20 minutes of irradiation. A significant decline in the FIB activity was observed with increasing light intensities, although no significant difference was found after 30 minutes of irradiation. The irradiation time was found to be significantly correlated with the loss activity of coagulation factors, regardless of the light intensities. Conclusion LED white light can act as a new light source for methylene blue virus reduction. Under the right conditions it reduced viruses effectively and preserves the activity of the coagulation factors in plasma.

Key words: LED white light, Methylene blue, Viral reduction