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Background: Ultraviolet (UV) fluorescent lamp (FL) was applied in mainstream riboflavin photochemical method (RPM) to inactivate pathogens in blood components. Low UV irradiance emitted by UV-FL resulted in more time to achieve effective inactivation., Materials and Methods: A novel light emitting diode (LED) UV illumination with adjustable irradiance was developed by us. Two strains of drug-resistant bacteria (DRB), pan-drug resistant Acinetobacter baumannii (PDRAB) and methicillin-resistant Staphylococcus aureus (MRSA) were cultured and used for evaluating the inactivation effectiveness of RPM using UV-LED or UV-FL against DRB in plasma or platelets. Three plasma factors and four platelet parameters were measured after treatments., Results: There was a linear relationship between UV-LED irradiance and electric current, the minimum UV irradiance was 24 mW/cm 2 , and the maximum was 258 mW/cm 2 . At the same UV dose of 15 J/cm 2 , inactivation effectiveness of UV-LED with 258 mW/cm 2 against PDRAB in plasma or platelets were comparable to that of UV-FL with 16 mW/cm 2 , both above 98%. UV-FL treatment required 10-15 min, but UV-LED only required 1-2 min. However, MRSA showed a resistance to UV-LED (inactivation effectiveness was around 40%) compared with UV-FL (inactivation effectiveness was above 98%). The retention of fibrinogen, factor V, factor VII in plasma and platelet counts in platelets with UV-LED treatment were significantly higher than UV-FL at the same UV dose., Conclusion: The treatment of RPM using UV-LED with high UV irradiance was able to dramatically shorten inactivation time against PDRAB in plasma or platelets and improve retention of blood components compared with UV-FL., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Photodynamic inactivation (PDI) is a non-invasive and safe therapeutic method for microbial infections. Bacterial antibiotic resistance is caused by antibiotics abuse. Drug-resistant Acinetobacter spp. is a serious problem in hospitals around the world. These pathogens from nosocomial infections have high mortality rates in frailer people, and Acinetobacter spp. is commonly found in immunocompromised patients. Visible light is safer than ultraviolet light (UV) for PDI of nosocomial pathogens with mammalian cells. Zinc oxide nanoparticles (ZnO-NPs) were used in this study as an antimicrobial agent and a photosensitizer. ZnO is recognized as safe and has extensive usage in food additives, medical and cosmetic products. In this study, we used 0.125 mg/ml ZnO-NPs combined with 10.8 J/cm 2 blue light (BL) on Acinetobacter baumannii (A. baumannii) that could significantly reduce microbial survival. However, individual exposure to ZnO-NPs does not affect the viability of A. baumannii. BL irradiation could trigger the antimicrobial ability of ZnO nanoparticles on A. baumannii. The mechanism of photocatalytic ZnO-NPs treatment for sterilization occurs through bacterial membrane disruptions. Otherwise, the photocatalytic ZnO-NPs treatment showed high microbial eradication in nosocomial pathogens, including colistin-resistant and imipenem-resistant A. baumannii and Klebsiella pneumoniae. Based on our results, the photocatalytic ZnO-NPs treatment could support hygiene control and clinical therapies without antibiotics to nosocomial bacterial infections., (Copyright © 2018. Published by Elsevier B.V.)