A team from the Autonomous University of Madrid (UAM) has developed paper sensors with rare-earth nanoparticles capable of detecting small concentrations of glucose in aqueous solutions. The work, published in the journal Colloids and Surfaces B: Biointerfaces, offers a non-invasive alternative for measuring glucose levels in patients with diabetes, eliminating the need to prick fingers to draw blood.
A team of researchers from the Autonomous University of Madrid (UAM), in collaboration with Concordia University in Montreal, has developed fluorescence-based paper sensors capable of measuring small concentrations of glucose in water.
The work represents a breakthrough in the non-invasive detection of glucose in patients with diabetes by proposing measurement through tear fluid, a less invasive and painful method than the traditional finger prick to draw blood.
The new sensors use nanoparticles doped with neodymium and erbium, two types of rare earth ions. The work, published in the journal Colloids and Surfaces B: Biointerfaces , thus paves the way for the development of rare-earth-based glucose sensors that could significantly improve the quality of life of patients with diabetes.
Fluorescent nanoparticles
Tear fluid contains significantly lower glucose concentrations than blood, requiring highly sensitive tools for detection, such as rare earth-doped nanoparticles.
These nanoparticles are notable for their unique optical properties, including their ability to generate visible light and how this can be affected by the surrounding medium. It is precisely these changes in the visible light emission of the nanoparticles, induced by the glucose molecule, that have been used to measure their concentration.
Nanoparticles are capable of producing emissions in the visible range of the spectrum, specifically at wavelengths associated with the colors green and red. In the absence of glucose, the probability of emitting green light is greater than that of emitting red light.
"However, when glucose is close to the nanoparticles, the OH groups present in the molecule interact with the nanoparticles, ’stealing’ population from the energy levels that generate green light and transferring it to the levels that generate red light, thus increasing the probability of red light emission," the authors explain.
"Therefore, changes in the intensities of the green and red bands can be associated with different glucose concentrations."
López-Peña, G.; Ortiz-Mansilla, Eva.; Arranz, A.; Bogdan, N.; Manso-Silván, M.; Martín Rodríguez, E. / UAM
The experiments conducted by the researchers effectively demonstrated the high sensitivity of these nanoparticles, obtaining a minimum reliably detectable value of 22 mg/dL. "This is an excellent result, since the concentration of glucose in tear fluid of patients with diabetes is in the range of 0 to 84 mg/dL. Thanks to this high detection capability, there is no need to add enzymes or other elements to increase its sensitivity, which reduces the cost and preparation time of the sensors."
"Moreover," the authors conclude, "by incorporating the nanoparticles into a porous medium such as paper, an inexpensive, easy-to-prepare, portable sensor with high sensitivity is achieved.
Bibliographic reference:
López-Peña, G.; Ortiz-Mansilla, Eva.; Arranz, A.; Bogdan, N.; Manso-Silván, M.; Martín Rodríguez, E. (2024). Non-invasive paper-based sensors containing rare-earth-doped nanoparticles for the detection of D-glucose. Colloids and Surfaces B: Biointerfaces, 30;239:113934.
doi: 10.1016/j.colsurfb.2024.113934.
More scientific culture in UAM Gazette
