Chicken IgG [FITC]

Polydimethylsiloxane (PDMS) is a hydrophobic elastomer commonly used for microfluidic fabrication. PDMS has to be modified to improve its hydrophilicity and thus inhibits non-specific protein adsorption. This work evaluates the modification materials for the development of microfluidic cell-based immunofluorescence (IF) assay. In cell-based IF assay, PDMS is modified not just to inhibit the adsorption of non-specific florescent-conjugated protein that causes the elevation of background signal, but also to firmly support cell adhesion for subsequent immunostaining procedure. PDMS materials modified by three regular modification materials consisting of an extracellular matrix (poly-L-lysine; PLL), a hydrophilic polymer (polyvinyl alcohol; PVA) and a non- ionic surfactant (pluronic F127) were compared with each other based on hydrophilicity improvement, minimization of non-specific background signal, and enhancement of human embryonic kidney (HEK) cell adhesion. Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) analysis confirms that all modification materials are successfully immobilized on the PDMS surfaces. Due to its antifouling mechanism, pluronic modification greatly improves the hydrophilicity of the PDMS and inhibits non-specific protein adsorption. Even though the hydrophilicity and non-specific protein adsorption resistivity of the PDMS modified with PLL did not significantly differ from those of the unmodified PDMS, PLL modification obviously promotes HEK cell adhesion. Negative control and Myelin Oligodendrocyte Glycoprotein (MOG) expressing HEK cells were immobilized in microfluidics for IF assay evaluation. Results demonstrate that positive MOG expressing cells can be selectively stained by anti-MOG IgG antibody within 1 h at room temperature. Microfluidic platforms also enhance immobilized cell distribution, which compatibly supports single-cell analysis technique.

We present a case series of three patients with COVID-19 who were admitted to our intensive care unit due to acute respiratory distress syndrome, brain infarction, pulmonary embolism, and antiphospholipid antibodies. We applied therapeutic plasma exchange on all cases. On intensive care unit admission, all patients had low (<10) Glasgow Coma Scale, and central nervous imaging showed multiple brain infarctions. COVID-19 was confirmed by reverse transcriptase polymerase chain reaction assays. Patients underwent rescue therapeutic plasma exchange using the Spectra OptiaTM Apheresis System (Terumo BCT Inc., USA), which operates with acid-citrate dextrose anticoagulant as per Kidney Disease Improving Global Outcomes 2019 guidelines. A dose of 1.5 plasma volume was used for the first dose and then 1 plasma volume daily for a total of five doses. Plasma was replaced with Octaplas LG (R) (Octapharma AG, USA), which is an artificial fresh frozen plasma product that has undergone viral inactivation by prion reduction technology. We administered ARDS-net/prone positioning ventilation, empiric antiviral treatment, therapeutic anticoagulation, and intensive care unit supportive care. Laboratory tests showed lymphocytopenia; elevated levels of D-dimer, fibrinogen, total bilirubin, C-reactive protein, lactate dehydrogenase, and ferritin; as well as low levels of ADAMTS-13 activity and antibody. Serology tests depicted positive IgM and IgG antiphospholipid antibodies (anti-cardiolipin and anti-ss 2-glycoprotein I antibodies). No side effects of therapeutic plasma exchange were recorded. After the completion of therapeutic plasma exchange, patients improved clinically and gradually recovered neurologically (after 27-32 days). To conclude, in life-threatening COVID-19, especially when immune dysregulation features such as antiphospholipid antibodies exist, therapeutic plasma exchange could be an effective rescue therapy.