Real-Time Monitoring of Glycemic Starch Using Biosynthesized Gold Nanoparticle-Amylase Composites

The enzymatic biosynthesis of gold nanoparticles (AuNPs) is achieved by the in situ reduction of gold ions with the help of the a-amylase enzyme as a reducing cum linking agent. Subsequently, the as-synthesized AuNP-a-amylase nanocomposite shows a host of exciting enzymatic activities toward the rapid degradation of starch when the size is varied from & SIM;10 to & SIM;40 nm. The nanocomposite has a superior activity as compared to free a-amylase for starch degradation. Importantly, the AuNP-a-amylase nanocomposite is utilized for the classification of rapidly (RDS) and slowly digestible starch (SDS) alongside resistant starch (RS) with the help of a standard 5 min starch hydrolysis experiment, based on the amount of maltose produced. Consequently, a point-of-care device has been developed for the real-time determination of the glycemic index (GI) of different food sources wherein the concentration of maltose produced after hydrolysis of starch by the nanocomposite is determined by chronoamperometry using screen-printed electrodes. In this device, maltose reduces [Fe(CN)(6)](3-) to [Fe(CN)(6)](4-) to generate a current signal proportional to the amount of maltose produced after starch hydrolysis by the nanocomposite. Concisely, the study demonstrates a simple, fast, reliable, portable, and inexpensive point-of-care testing (POCT) prototype for real-time determination of the GI of food sources.

Automated summary

The enzymatic biosynthesis of gold nanoparticles (AuNPs) using α-amylase as a reducing and linking agent was achieved through in situ reduction of gold ions. The resulting AuNP-α-amylase nanocomposite exhibited exciting enzymatic activities in degrading starch rapidly. This nanocomposite demonstrated superior starch degradation activity compared to free α-amylase. Additionally, it was utilized for the classification of different types of starch and the development of a point-of-care device for real-time determination of the glycemic index (GI) of food sources.