Table 1.
Characteristics of pathogen inactivation systems [17, 20, 21].
Fig 1.
(a) Samples were placed in a siliconized quartz glass dish (28-mm inner diameter) with a stir bar. Eight UV-LED units (265 nm) were placed on the board face down for irradiation; the distance between the UV-LED and the sample surface before sampling was 17.7 mm. (b) The emission spectrum of the UV-LED used in this study.
Fig 2.
UV-LED inactivation of bacteria in the plasma-PC milieu.
PC samples (2.75 mL) inoculated with 6 × 103–2 × 104 cfu of (a) E. coli, (b) S. aureus, and (c) B. cereus were irradiated with UV-LED at 265 nm up to 30 min. Samples (100 μL) were taken every 5 min and incubated overnight for colony count determination. Mean cfu of (a) E. coli, (b) S. aureus, and (c) B. cereus from 100-μL PC samples before irradiation were 50.8, 28.5, and 38.8, respectively. The survival rate was determined as the cfu at each sampling time relative to the cfu before irradiation. The control samples (without UV-LED irradiation) and UV-LED-irradiated samples are displayed as open and closed circles, respectively. The mean value of six independent experiments is shown as a solid line. Those not-detected (ND) are shown as grey circles, and the limits of detection for (a) E. coli, (b) S. aureus, and (c) B. cereus were 0.017, 0.014, and 0.016, respectively. Based on the mean value of 58.6 (cm-1) as the 265 nm absorbance for the PC samples tested (n = 520), the average irradiance (adjusted using the Beer-Lambert law) was 0.0156 mW/cm2. Thus, on average, irradiation times of 5, 10, 15, 20, 25, and 30 min correspond to fluence values of 4.6, 9.2, 13.9, 18.6, 23.5, and 28.5 mJ/cm2, respectively.
Fig 3.
Effects of UV-LED irradiation on platelet counts and aggregation.
(a) Seven independent experiments of control (non-irradiated) and UV-LED-irradiated samples are displayed as open and closed circles, respectively. Mean values ± SD are shown as one long and two short horizontal bars. Based on the mean absorbance of PC samples, irradiation times of 5, 10, 15, 20, 25, and 30 min correspond to fluence values of 4.6, 9.2, 13.9, 18.6, 23.5, and 28.5 mJ/cm2, respectively. (b) After a 60-min irradiation, PCs were fixed with 1% paraformaldehyde (PFA). For preparation of agonist-induced aggregation, PCs were incubated with 10 μg/mL collagen and 20 μM ADP for 5 min and subsequently fixed with PFA (inset). A representative image from three independent experiments is shown. Arrowheads indicate UV-LED-induced aggregates.
Fig 4.
Effect of UV-LED irradiation on platelet surface molecules.
Surface expressions of (a) CD42b, (b) CD61, (c) the activated form of GPIIb/IIIa, and (d) CD62P were measured. Five (a, b) and seven (c, d) independent experiments of the control (non-irradiated) and UV-LED-irradiated platelets are displayed as open and closed circles, respectively. Mean values ± SD are shown as one long and two short horizontal bars. (a, b, d) Based on the mean absorbance of PC samples, irradiation times of 0, 5, 10, 15, 20, 25, and 30 min correspond to fluence values of 0, 4.6, 9.2, 13.9, 18.6, 23.5, and 28.5 mJ/cm2, respectively. (c) Irradiation times of 0, 10, 20, and 30 min correspond to fluence values of 0, 9.1, 18.3, and 27.7 mJ/cm2, respectively.
Fig 5.
Effect of UV-LED irradiation on agonist-induced platelet aggregation.
(a) Platelet aggregation induced by collagen (final concentration, 5 μg/mL), (b) ADP (final concentration, 20 μM), and (c) a mixture of ADP and collagen (final concentrations of 5 μM and 2.5 μg/mL, respectively) are shown. Six independent experiments of control (non-irradiated) and UV-LED-irradiated samples are displayed as open and closed circles, respectively. Mean values ± SD are shown as one long and two short horizontal bars. Based on the mean absorbance of PC samples, irradiation times of 10, 20, and 30 min correspond to fluence values of 9.1, 18.3, and 27.7 mJ/cm2, respectively. (a-c right panels) PCs were irradiated with UV-LED for 30 min. Platelets were then diluted as described in the Materials and Methods and stimulated with agonists at time 0 (arrow). Aggregation curves of irradiated (UV-LED (+)) and non-irradiated (UV-LED (−)) platelets are displayed as black and grey lines, respectively. Representative data are shown.
Fig 6.
Effect of UV-LED irradiation on adhesion and aggregation to collagen under flow conditions.
PCs were irradiated with UV-LED for 30 min. Non-irradiated (UV-LED (−)) and UV-LED-irradiated (UV-LED (+)) platelets were loaded using low (100 s-1) and high (1,000 s-1) shear rates, and images were obtained after 5 and 2 min of flow, respectively. (a) Representative images from six independent experiments are shown. (b) Six independent experiments of control (non-irradiated, ((−)) and UV-LED-irradiated (+) samples are displayed as open and closed circles, respectively. Mean values ± SD are shown as one long and two short horizontal bars.
Fig 7.
Absorbance (265 nm) of PC samples.
PC samples (n = 520; 100-fold dilution) were applied to spectrophotometric analysis to determine absorbance at 265 nm. (a) A dot plot of 520 independent analyses is shown. (b) Linear regression analysis of platelet counts and absorbance at 265 nm.
Table 2.
Characteristics of UV irradiation techniques.
Data extrapolated from reports.
Table 3.
Effect of UV irradiation techniques on platelets functions.
Data extrapolated from reports.