Chemiluminescence (CL) of luminol with hydrogen peroxide is useful for the highly sensitive determination of biochemicals by conjugation with oxidase. However, the method has stability problems because reactant-mixing conditions influence the results. However, electrochemiluminescence (ECL) of luminol can be performed on well-mixed solutions of luminol and hydrogen peroxide. ECL has not yet been applied to the quantitative analysis of biochemical due to low quantum yields at physiological pH. In this work, we evaluated the effect of modifying the electrode with cationic polymer on the ECL intensity of luminol. Transparent indium-tin oxide (ITO) electrode was treated with 1 wt% aqueous solution of polyethyleneimine (MW:70,000) buffered by 0.1 M borate at pH 8.0. ECL intensity at the ITO electrode was measured in a mixed solution of 1.0 mM luminol and 10-30 μM hydrogen peroxide buffered by phosphate or Tris-HCl (pH 7.4). The electrode potential was applied in alternate pulses of 0.00 V versus Ag/AgCl for 3 s and 1.00 V for 3 s. The sensitivity of ECL to hydrogen peroxide concentration at the treated ITO increased remarkably. Results indicate that the cationic polymer adsorbed on the electrode enhances ECL by increasing pH in the vicinity of the electrode surface. However, the cationic polymer also enhanced inhibition of ECL by ascorbic acid, an anionic reducing reagent.
This paper reports on the microfluidic perfusion culture of human induced pluripotent stem cells (hiPSCs) under fully defined culture condition. By screening various ECMs we determined that fibronectin and laminin are appropriate for microfluidic devices made out of the most popular material, polydimethylsiloxane (PDMS). We found that the growth rate of hiPSCs under pressure-driven perfusion culture conditions was higher than under static culture conditions in the microchamber array. We believe that our system will be a platform technology for future large-scale screening of fully defined conditions for differentiation cultures on integrated microfluidic devices.
A 53-year-old man was admitted to our hospital with thoracic back pain and weight loss. Computed tomography revealed inflammatory aortic aneurysm (IAA) of the descending aorta. Sealed rupture of the aneurysm occurred while the patient was under corticosteroid therapy. Endovascular aneurysm repair (EAR) was performed without postoperative complications. Periaortic fibrosis was remarkably decreased three months later while the patient was under prednisolone (20 mg) administration. We believe that EAR could become a practical alternative to open surgical repair. The possibility of an aneurysm rupturing during corticosteroid therapy for IAA should be considered.
