Glucose monitors and testing strips are essential devices in maintaining the health of diabetics and individuals that suffer from urinary tract infections. However, testing materials is often too expensive or impractical for those who require them. An estimated 80% of undiagnosed diabetics live in low- to middle- income areas, reducing the likelihood that these individuals will have access to or be able to afford testing materials . To combat the inaccessibility of glucose monitors and testing strips, researchers at the University of Cambridge have developed reusable, affordable automatic photonic nanosensors with nanotechnology.
In a photonic nanosensor, a matrix of phenylboronic acid-functionalized hydrogel is embedded with silver nanoparticles (AgNPs) through a process known as laser writing, in which a 6 ns (nanosecond, referring to pulse duration) laser is used to organize the AgNPs into a specific pattern . This pattern of AgNPs is a periodic variation (imperfection) in the refraction index of the hydrogel, and will produce a specific wavelength when light passes through it. This is an example of a volume Bragg grating in which a transparent material is modified (in this case with the AgNPs) to produce an interference pattern, which causes the material to reflect a small range of wavelengths and transmit all else . When a user’s glucose levels are high, they expand the hydrogel and alter the spacing of the nanoparticles, causing a wavelength to be emitted which is different in color from the wavelength produced when the gel is contracted . To test glucose levels, individuals would insert a blood, urine, or teardrop sample into the sensor containing the hydrogel matrix embedded with AgNPs, causing the hydrogel to expand to varying dimensions. A light within the nanosensor would then refract off the hydrogel to give a visible readout of colored light, indicating the level of glucose present in the sample.
This colormetric method of testing glucose concentration is both cheaper and more effective than traditional means of measuring glucose levels through electrical currents . The colormetric sensors can be mass-produced using pre-programmed laser writing techniques, making them available for wide-spread distribution in developing nations. By creating accessible screening technology for type 1 and type 2 diabetes, development of equally accessible treatments can begin as well. Some treatments that incorporate nanotechnology include nanoparticle coatings to protect orally delivered insulin, artificial pancreases utilizing silicon nanoparticles, and nanopumps for continuous delivery of insulin.
Hydrogel expanding with the increase in glucose concentration. (Yetisen et. al, 2014)
- "Nanotechnology Takes on Diabetes." University of Cambridge. N.p., 30 May 2014. Web. 01 July 2015.
- Yetisen, Ali K., Yunuen Montelongo, Fernando Da Cruz Vasconcellos, J.l. Martinez-Hurtado, Sankalpa Neupane, Haider Butt, Malik M. Qasim, Jeffrey Blyth, Keith Burling, J. Bryan Carmody, Mark Evans, Timothy D. Wilkinson, Lauro T. Kubota, Michael J. Monteiro, and Christopher R. Lowe. "Reusable, Robust, and Accurate Laser-Generated Photonic Nanosensor." Nano Letters Nano Lett. 14.6 (2014): 3587-593. Web.
- Paschotta, Rüdiger. "Bragg Gratings." Encyclopedia of Laser Physics and Technology. N.p., n.d. Web. 01 July 2015.
- "MIT School of Engineering." How Do Glucometers Work? N.p., 18 Oct. 2011. Web. 01 July 2015.
- Awadhesh, Arya. Et. al. "Applications of Nanotechnology in Diabetes Mellitus."Applications of Nanotechnology in Diabetes Mellitus. N.p., 15 Oct. 2008. Web. 01 July 2015.
Colormetric glucose meters using photonic nanosensors cost only 30 cents to manufacture due to the mass production benefits of laser writing techniques, and are reusable up to 400 times while maintaining accurate readings. Traditional glucose testing strips cost 15 cents for each disposable testing strip and use only a fresh blood sample while colormetric glucose meters can utilize blood, saliva, urine, or tear samples. Colormetric glucose meters also showed improved or comparable performance to commercial and state-of-the-art glucose monitors in trials .
Colormetric glucose testing strips pose little physical risk to patients other than reduced accuracy through overuse which is not recommended. However, their intended purpose, to provide simple, effective, reusable testing strips to developing nations, may be impacted due to issues of distribution. While the technology may be mass producible and affordable, getting the materials to those who need them depends heavily on a country’s infrastructure and government.