Electrochemical impedance spectrum frequency optimization of bitter taste cell-based sensors.

Electrochemical impedance spectrum frequency optimization to bitter taste receptor cell-based sensors is discussed in this paper. The bitter taste receptor cells (the enteroendocrine STC-1 cells and the ICR mouse isolated taste bud cells) are cultured on carbon screen printed electrodes and used as sensing elements. The HEK-293 cells and dead isolated ICR mouse taste bud cells, without bitter taste receptor expression, are used in negative control experiments. The electrochemical impedance spectrum data is recorded and processed by bistable stochastic resonance for signal-to-noise ratio analysis. The bitter taste receptor cell-based sensor selectively responds to bitter tastants. The tastants species and concentrations can be decided by signal-to-noise ratio parameters. The signal-to-noise ratio eigen peak changes with the shift of electrochemical impedance spectrum frequencies. ICR mouse isolated taste bud cell-based sensor presents bitter tastants perception abilities. 9kHz is the optimal frequency for STC-1 cell-based sensor measurement. For isolated ICR mouse taste bud cells, 1.2kHz is the optimal frequency. Negative control experiments results indicate that cells with no taste receptor expression have no discriminating ability for tastant even if they are modulated by different frequencies. The taste cell-based sensor is of great practical value.

Sweet and bitter tastants specific detection by the taste cell-based sensor.

Sweet and bitter tastants specific detection by cell-based sensor is investigated in this paper. Human enteroendocrine NCI-H716 cells, expressing G protein-coupled receptors and sweet receptors (type 1, member 2/type 1, member 3), and human enteroendocrine STC-1 cells, expressing G protein-coupled receptors and bitter receptors (type 2 members) are used as sensing devices. The HEK-293 cells, without taste receptor expression, are used as negative control. The electrochemical impedance spectrum data is recorded and processed by bistable stochastic resonance for signal-to-noise ratio calculation. NCI-H716 cell-based sensor selectively responds to sweeteners and sweet tastant mixtures. STC-1 cell-based sensor selectively responds to bitter tastants and bitter tastant mixtures. The tastants species and concentrations can be decided by signal-to-noise ratio parameters. HEK-293 cell-based sensor lacks the tastants discriminating ability. The taste cell-based sensor is easy to prepare and operate. This work offers a useful way in gustatory mechanism research.

[Effects of ionic-dissolution of sol-gel bioactive glasses on human dental pulp cells].

OBJECTIVE: To evaluate the effects of ionic-dissolution of sol-gel bioactive glasses (BG) on proliferation and alkaline phosphatase (ALP) activity of human dental pulp cells (HDPCs) . METHODS: The primary HDPCs were isolated from intact premolar and third molars and were cultured in DMEM. Then the 4 th generation of HDPCs were cultured in DMEM, which contained 1 g/L of one of 58S, Nano-58S, and 45S5 ionic-dissolution products. Meanwhile HDPCs were cultured in DMEM without BG as control group. Proliferation of the cells was evaluated by MTT assay on days 1,3,5 and 7. ALP activity was measured on day 14 using ALP Assay Kit. RESULTS: Compared with the control group, HDPCs' proliferation in the Nano-58S group increased significantly. HDPCs cultured in Nano-58S and the 58S groups showed higher ALP activity (P<0.01); but in 45S5 group showed an inhibition on the HDPCs' proliferation (P<0.01) and lower ALP activity (P<0.05). CONCLUSION: Present work has shown that Nano-58S and 58S sol-gel BG can promote the proliferation and ALP activity of HDPCs.