We developed a new plasmonic nanostripe microcone array
(PNMA)
substrate-integrated microfluidic chip for the simultaneous surface-enhanced
Raman scattering (SERS)-based immunoassay of the creatine kinase MB
isoenzyme (CK-MB) and cardiac troponin (cTnI) cardiac markers. The
conventional immunoassay usually employs a microtiter plate as the
solid capture plate to form the immunocomplexes. However, the two-dimensional
(2D) surface of the microtiter plate limits the capture efficiency
of the target antigens due to the steric hindrance effect. To address
this issue, a gold film-coated microcone array with nanostripes was
developed that can provide a large surface area for capture antibody
conjugation and serve as a SERS-active substrate. This unique nano–microhierarchical
structure showed an excellent light trapping effect and induced surface
plasmon resonance to further enhance the Raman signals of the SERS
nanoprobes. It significantly improved the sensitivity and applicability
of SERS-based immunoassay on the microfluidic chip. With this integrated
microfluidic chip, we successfully performed the simultaneous detection
of CK-MB and cTnI, and the detection limit can reach 0.01 ng mL–1. It is believed that the PNMA substrate-integrated
microfluidic chip would play a critical role in the rapid and sensitive
diagnostics of cardiac diseases.
Catalytic conversions of bioethanol to propylene were investigated over different zeolite catalysts. H-ZSM-5 (SiO2/Al2O3 = 80) was found to be the most effective for propylene production. Furthermore, H-ZSM-5 (SiO2/Al2O3 = 80) was investigated under different variables of catalytic reaction (calcination temperature, feed composition, reaction temperature, and time on stream) for the conversion of ethanol to propylene. The H-ZSM-5(80) catalysts calcined at 600 °C showed the highest propylene yield. The moderate acidic site on ZSM-5 is required for the production of propylene. The activity on ZSM-5 is independent of the ethanol feed composition. H-ZSM-5 catalyst deactivation was observed, owing to dealumination. The highest propylene yield was 23.4% obtained over HZSM-5(80). Propylene, butene, and ≥C5 olefins were formed by parallel reaction from ethylene. Olefins were converted to each paraffin by sequential hydrogenation reaction. HZSM-5(80) catalyst is a promising catalyst not only for ethanol but also for the conversion of bioethanol to light olefins.
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