3D-printed CuO nanoparticle–functionalized flow reactor enables online fluorometric monitoring of glucose
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An online flow reactor was fabricated by using a fused deposition modeling three-dimensional printing (3DP) technology along with thermoplastic poly(lactic acid) filaments incorporating copper oxide nanoparticles (CuO NPs). In the presence of glucose, the flow reactor displays multi-catalytic activities because accelerates the oxidation of 2′,7′-dichlorodihydrofluorescein to form fluorescein which displays green fluorescence under 480 nm excitation (emission wavelength: 530 nm). The CuO NPs exert two functions to mediate electron transfer at a basic reaction condition, viz. direct oxidation of glucose to generate reactive oxygen species (ROS), and prompting the ROS to oxidize 2′,7′-dichlorofluorescin diacetate. The flow reactor coupled to a microdialysis sampler and a fluorometer was applied for online fluorometric monitoring of brain extracellular glucose levels in living rats based on scanning of time-resolved fluorescence intensities. After optimization of (a) the manufacture of the flow reactor, (b) the reaction conditions (pH 10; 50 °C), and (c) the online analytical system, the detection limit of the method (when using 10-μL samples of microdialysate) is as low as 6.1 μM (linear range: 0.05–5 mM) with a sampling frequency of 7.5 h−1. To illustrate the method’s applicability, analyses of spiked off-line-collected rat brain microdialysates were conducted. In addition, rat brain extracellular glucose levels were monitored in-vivo and online upon neuronal depolarization triggered by perfusing a high-K+ medium. The results demonstrate that functionalizing raw 3DP materials with appropriate nanomaterials can simplify the manufacturing of analytical devices and related analytical procedures. This will extend the diversity and adaptability of current 3DP-enabling analytical strategies.
KeywordsAdditive manufacturing Brain extracellular fluid CuO nanoparticles DCFH-DA Enzyme mimic In vivo monitoring Incorporation Reactive oxygen species
We thank Professor Yuh-Chang Sun for providing helpful advice, and the Ministry of Science and Technology of the Republic of China for financial support (grant MOST 106-2113-M-019-002-MY2).
Compliance with ethical standards
The author(s) declare that they have no competing interests.
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