Microchip electrophoresis‐single wall carbon nanotube press‐transferred electrodes for fast and reliable electrochemical sensing of melatonin and its precursors

Abstract

In the current work, single-wall carbon nanotube press-transferred electrodes (SW-PTEs) were used for detection of melatonin (MT) and its precursors tryptophan (Trp) and serotonin (5-HT) on microchip electrophoresis (ME). SW-PTEs were simply fabricated by press transferring a filtered dispersion of single-wall carbon nanotubes on a nonconductive PMMA substrate, where single-wall carbon nanotubes act as exclusive transducers. The coupling of ME-SW-PTEs allowed the fast detection of MT, Trp, and 5-HT in less than 150 s with excellent analytical features. It exhibited an impressive antifouling performance with RSD values of ≤2 and ≤4% for migration times and peak heights, respectively (n = 12). In addition, sample analysis was also investigated by analysis of 5-HT, MT, and Trp in commercial samples obtaining excellent quantitative and reproducible recoveries with values of 96.2 ± 1.8%, 101.3 ± 0.2%, and 95.6 ± 1.2% for 5-HT, MT, and Trp, respectively. The current novel application reveals the analytical power of the press-transfer technology where the fast and reliable determination of MT and its precursors were performed directly on the nanoscale carbon nanotube detectors without the help of any other electrochemical transducer.

Carbon nanotubes in microfluidic lab-on-a-chip technology: current trends and future perspectives

“…SWCNTs filtered on a non-conductive PMMA substrate acted as transducers. This system resulted in rapid detection of melatonin, tryptophan and serotonin in periods shorted than 150 s (Gomez et al 2015). Furthermore, it was found that an amperometric sensor could be made of CNTs and ferrocene (as a redox-responsive reporter) that was applied in order to detect pathogenic viral DNA from hepatitis C and genomic DNA from Myocobacterium tuberculosis with high sensitivity (Zribi et al 2016).…”

Electrochemical detectors based on carbon and metallic nanostructures in capillary and microchip electrophoresis

“…In this sense, the most used ones not only in electrochemical sensing, but also as detectors coupled to ME and CE have been CNTs and GP . On the one hand, CNTs, differently from wires described in the following section, are rolled cylinders consisting of one layer of sp 2 carbon‐bonded atoms, single‐walled carbon nanotubes (SWCNTs) or generated by rolling few layers of sp 2 carbon layers, multiwalled carbon nanotubes (MWCNTs) .…”

“…These electrodes allow high resistance to fouling, and good stability of the press‐transferred films in PMMA substrates, as shown in Fig. C, in a clinical application of these detectors for the determination of melatonin, its precursor tryptophan, and its derivative serotonin 5‐hydroxytryptamine . Press transfer electrodes have been also used in the food‐chemistry sector for the isoflavone index determination based on the comigration of the total glycosides and total aglycones in soy samples .…”

Rapid and inexpensive method for the simple fabrication of PDMS‐based electrochemical sensors for detection in microfluidic devices

“…Microfluidics‐based systems such as microchip electrophoresis (ME) offer advantages over macro‐scale platforms that include portability, lower consumption of reagents and samples, miniaturized dimensions, faster analysis, and reduced waste generation . ME devices can be fabricated using several materials such as silicon, glass, PMMA, and PDMS .…”