Colorimetric Glucose Detection

What Is Colorimetric Glucose Detection? 

Colorimetric glucose detection involves the use of metal nanoparticles of specific physical and chemical properties that change colour following a series of reactions. Commonly, gold or silver nanoparticles are used in the sensor and can be coupled together to create a new set of properties depending on the application. This page will focus on the use of gold nanoparticles (AuNPs) as a biosensor application. 

Gold Nanoparticles

Gold nanoparticles (AuNPs) exhibit various colours in solution ranging from brown to purple, depending on the core size. The nanoparticle synthesis method used for this biosensor produces 18-25nm spherical gold nanoparticles with a wine red colour. Many other synthesis methods for this application are used frequently, producing nanoparticles with a large range of sizes. For more information on gold nanoparticle synthesis, refer to the Nanoparticle Synthesis page. 

Reactants Involved in Glucose Detection

Glucose Oxidase (GOx) is a key enzyme utilized in glucose sensing. It not only has the ability to selectively determine glucose, but when in the presence of an aqueous gold solution, it is able to synthesize nanoparticles. HAuCl₄ is the aqueous gold solution that is utilized in nanoparticle synthesis and is also a key element in the enzymatic growth of gold nanoparticles. These two elements partake in reactions that result in a visible colour change, which is correlated with various glucose concentrations. 

Other reactants typically used for glucose sensors are gold nanoparticles, phosphate buffer (which is mixed with GOx), glucose (analyte), and Milli-Q water (for diluting the solution).  

References

[1] Y. Xiong, Y. Zhang, P. Rong, J. Yang, W. Wang, and D. Liu, “A high-throughput colorimetric assay for glucose detection based on glucose oxidase-catalyzed enlargement of gold nanoparticles,” Nanoscale, 27-Aug-2015. [Online]. Available: http://xlink.rsc.org/?doi=C5NR03758A&newsite=1.

[2] nanoComposix, “Gold Colloid,” nanoComposix. [Online]. Available: https://nanocomposix.com/pages/gold-colloid.