Environmental, healthcare sensor: Thiourea testing

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  • Published: Oct 1, 2017
  • Author: David Bradley
  • Channels: UV/Vis Spectroscopy
thumbnail image: Environmental, healthcare sensor: Thiourea testing

The dope

Co-doped manganese oxide nanoparticles (CMOs) can be made with a facile hydrothermal method and used in an emzyme-free, yet highly sensitive thiourea sensor. A whole raft of analytical techniques, including ultraviolet-visible (UV-Vis) spectroscopy, was used to characterize the particles.

Co-doped manganese oxide nanoparticles (CMOs) can be made with a facile hydrothermal method and used in an enzyme-free, yet highly sensitive thiourea sensor. A whole raft of analytical techniques, including ultraviolet-visible (UV-Vis) spectroscopy, was used to characterize the particles.

The CMOs, which were ultimately incorporated into a glassy carbon electrode (GCE), were developed by Mohammed Rahmana and Abdullah Asiria of King Abdulaziz University, in Jeddah, Saudi Arabia, and Jahir Ahmed of Shahjalal University of Science and Technology, in Sylhet, Bangladesh. The team used Fourier transform infrared (FTIR) spectroscopy, FESEM (field emission scanning electron microscopy), XEDS (energy-dispersive X-ray spectroscopy), XPS (X-ray photoelectron spectroscopy), TEM (transmission electron microscopy), and XRD (X-ray diffraction) techniques, as well as UV/Vis spectroscopy in their investigations.

Thiourea represents a severe ecological contaminant. It provides organic sulfur with a facile route into ecosystems and living things and has detrimental effects on mammals, nitrifying bacteria, and the environment, in general. It is carcinogenic and a worrying allergen and can disrupt carbohydrate metabolism. However, it is a rather useful chemical in the electroplating industry, in the manufacture of rubber, in wet photography, analytical chemistry, and agriculture. "Thus," say the researchers, "a suitable, selective, low-cost method is needed to investigate this harmful chemical in waste water and environment."

Technical raft

The team points out that several techniques have been used to detect and determine thiourea in various samples previously, including titrimetry, a piezoelectric method, high-performance liquid chromatography (HPLC), FTIR spectroscopy, analysis by chemiluminescence, flow-injection methods, and UV/Vis spectroscopy. All of these techniques have their pros and cons as do the electrochemical methods that are impeded by the slow kinetics of thiourea conversion at a bare electrode.

Having focused on electrochemical methods as being potentially very sensitive, the team has now turned its attention to accelerating those slow kinetics to develop a non-naked electrode that can enhance the rate of electron transfer and reduce the over-potential needed for a reaction to take place that allows detection of the analyte. They have now demonstrated that the drawbacks associated with other electrode modifications can be overcome if CMOs are used to coat a GCE electrode. The nanoparticles themselves give a selective and specific redox reaction with thiourea. Moreover, the metal oxide nanoparticles offer exceptional electronic, catalytic and optical properties.

Consistent sensor

A prototype sensor shows high sensitivity and very low detection limit for thiourea detection, with what the researchers describe as an excellent linear response for a wide range of concentrations obtained with a very short response time. They suggest that the approach offers an effective and consistent method for analysis with potential applications in biomedical, healthcare, and environmental fields.

Related Links

Biosens Bioelectron 2018, 99, 586-592: "Thiourea sensor development based on hydrothermally prepared CMO nanoparticles for environmental safety"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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