Opsys mr microplate reader

Anti‐SARS‐CoV‐2‐spike IgG titers were determined by SERION ELISA agile SARS‐CoV‐2 IgG (SERION Diagnostics, Wuerzburg, Germany), technically carried out as an enzyme linked immunoassay (ELISA).
The extinction values were photometrically measured operating with the Dynex Opsys MR™ Microplate Reader and Relevation Quick Link (Dynex technologies) at 405 nm wavelength. The extinction was transferred to the manufacturer specific Serion IgG units per ml (U/ml) using the software easyANALYSE (SERION Diagnostics). These units were converted into the internationally established unit Binding Antibody Units per ml (BAU/ml) using the factor 2.1 according to the manufacturer's instructions.²¹The threshold IgG values in the selected SERION assay were defined as <10.0 U/ml (21.0 BAU/ml) for negative, ≥10.0 U/ml (21.0 BAU/ml) to <15.0 U/ml (31.5 BAU/ml) for results at the borderline and ≥15.0 U/ml (31.5 BAU/ml) as positive. These values were chosen according to manufacturer's instruction and IgG values above the threshold of 31.5 BAU/ml indicate at least a moderate neutralization capacity.²² For detecting anti‐SARS‐CoV‐2‐spike IgG antibody levels beyond the maximum limit of 250 U/ml (525.0 BAU/ml), serum blood samples were diluted based on a dilution series with dilution factors both 10 and 100. Consequently, the measurement range of SERION ELISA agile SARS‐CoV‐2 IgG could be expanded.

Blood samples (2.6 mL) were routinely collected from the patients at each of the following time points: (1) before the use of CPB, (2) after 60 min of the use of CPB, and (3) at 24 h after the beginning of the surgery. The collected blood samples were centrifuged at 1200× g for 10 min. The resulting serum and plasma fractions were stored at −20 °C until further analyses.
The concentration of the IgG antibody was measured by a competitive ELISA (enzyme linked immunosorbent assay) diagnostic test (CUSABIO, Wuhan, China). Direct ELISA diagnostic tests were applied for determining the concentrations of IgA (AccuDag, Beijing, China), IgD (Innovative Research, Novi, MI, USA), and IgM (CUSABIO, Wuhan, China), while indirect ELISA diagnostic tests were performed for measuring the concentrations of IgG3 (Abnova, Taipei, Taiwan) and IL-6 (RayBio, Peachtree Corners, GA, USA). Antibody-coated 96-well plates were used for ELISA tests, according to the manufacturer’s instructions. For each experiment, the samples were analyzed in duplicate, and a new standard curve was plotted using CurveExpert Professional software (CurveExpert Pro 2.3.0 started, with process ID 4648). Absorbance was measured using a Dynex Opsys MR Microplate Reader (Dynex Technologies, Chantilly, VA, USA) after its systematic validation for clinical analyses.

Commercial ELISA kits were used to measure the Aβ1–40 and Aβ1–42 (Aβ₁–₄₀ human ELISA kit, KHB 3482 and Aβ₁–₄₂ human ELISA kit KHB 3442, respectively; Invitrogen, Thermo Fisher Scientific, Waltham, MA, United States). Briefly, brain homogenates were diluted 1:50 in PBS-Tween-BSA buffer (0.03% Tween-20, 5% BSA in PBS) before centrifuging at 4°C for 20 min at 16,000 × g. Each assay was run in duplicate and the plate absorbance was measured at 450 nm using an Opsys MR microplate reader (Dynex Technologies).