AlGaN/GaN-based biosensor for label-free detection of biological activity

In this work, detection of live cell biological activity has been confirmed for label-free AlGaN/GaN based biosensors. Live cells were seeded in solution onto the exposed gate region of packaged AlGaN/GaN field effect transistor (FET) devices and subsequently subjected to various chemical changes in the solution. Cell depolarisation with KCl was used to induce biological signals. Significant optimisation of experimental parameters was performed, including environmental conditions and cell seeding concentration. Selectivity towards biological activity was improved by buffering with 30 mM 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES). Reproducible calcium concentration-dependent responses were observed with saturation at the normal physiological level of around 2.5 mM. Cells in a calcium-free solution were pre-treated in separate experiments with calcium ion channel inhibitors Mibefradil, Nisoldipine and HC-030031, and the calcium channel activator S-BayK(−)8644, before calcium dosing. The resulting responses were compared to depolarisation-induced calcium intake and demonstrated physiologically relevant behaviour of calcium ion channels.