Multiplexed Readout of Enzymatic Reactions by Means of Laterally Resolved Illumination of Quantum Dot Electrodes.
Shuang ZhaoJohannes VölknerMarc RiedelGregor WitteZhao YueFred LisdatWolfgang J ParakPublished in: ACS applied materials & interfaces (2019)
Triggering electrochemical reactions with light provides a powerful tool for the control of complex reaction schemes on photoactive electrodes. Here, we report on the light-directed, multiplexed detection of enzymatic substrates using a nonstructured gold electrode modified with CdSe/ZnS quantum dots (QDs) and two enzymes, glucose oxidase (GOx) and sarcosine oxidase (SOx). While QDs introduce visible-light sensitivity into the electrode architecture, GOx and SOx allow for a selective conversion of glucose and sarcosine, respectively. For the QD immobilization to the gold electrode, a linker-assisted approach using trans-4,4'-stilbenedithiol has been used, resulting in the generation of a photocurrent. Subsequently, GOx and SOx have been immobilized in spatially separated spots onto the QD electrode. For the local readout of the QD electrode, a new measurement setup has been developed by moving a laser pointer across the surface to defined positions on the chip surface. The amplitudes of the photocurrents upon illumination of the GOx or SOx spot depend in a concentration-dependent manner on the presence of glucose and sarcosine, respectively. This measurement also allows for a selective detection in the presence of other substances. The setup demonstrates the feasibility of multiplexed measurements of enzymatic reactions using a focused light pointer, resulting in an illumination area with a diameter of 0.3 mm for analyzing spots of different enzymes. Moving the laser pointer in the x- and y-direction and simultaneously detecting the local photocurrent also allow a spatial imaging of enzyme immobilization. Here, not only the spot dimensions but also the activity of the enzyme can be verified.
Keyphrases
- quantum dots
- carbon nanotubes
- transcription factor
- solid state
- stem cells
- hydrogen peroxide
- single cell
- blood glucose
- label free
- visible light
- sensitive detection
- gold nanoparticles
- loop mediated isothermal amplification
- drinking water
- metabolic syndrome
- high throughput
- magnetic nanoparticles
- silver nanoparticles
- type diabetes
- high speed
- reduced graphene oxide
- skeletal muscle
- energy transfer
- insulin resistance
- weight loss
- simultaneous determination