| Ecologists currently cannot test concentrations of carbohydrates in sap in vivo. Testing carbohydrates with current technology would require destructive tissue sampling. The tissue sampling involves large amounts of time and money to collect and test. Aphids are an insect that can bypass a tree's passive immune system and feed off a phloem region for weeks. A series of enzymatic biosensors could be used to detect the concentration changes of specific carbohydrates. A calcium chelant can be added to defeat a tree's immune system like an aphid. The detection of three carbohydrates, fructose, glucose and sucrose are involved in this study. Amperometric sensors were the first generation of sensors and had a linear range that only extended to 3.5wt% carbohydrate for glucose and fructose. The calcium chelant, EGTA, negatively affected sensor response even at low concentrations, like 0.25mM. The second generation of sensors, thermopiles, proved to have a better linear range, up to 10wt% carbohydrate for glucose and sucrose. EGTA did not have a significant effect on sensor response until a concentration of 15mM. |
