SEMINAR-III 28-09-09 SPEAKER KALPANA

1. SEMINAR-III 28-09-09 SPEAKER KALPANA

2. Impedimetric monitoring of cell attachment on interdigitated microelectrodes Bin-Wha Changa,b, Che-Hsiung Chena, Shin-Jyh Ding c, David Chan-Hen Chend, Hsien-Chang Changa,∗ aInstitute of Biomedical Engineering, National Cheng-Kung University, Tainan 701, Taiwan, ROC bDepartment of Healthcare Administration, Hung-Kuang University, Taichung 433, Taiwan, ROC cInstitute of Dental Materials, Chung-Shan Medical University, Taichung 402, Taiwan, ROC dInstitute of Veterinary Microbiology, National Chung-Hsing University, Taichung 402, Taiwan, ROC

3. 1.INTRODUCTION • Cell attachment is the initial step in tissue or tumor formation process including cell growth, migration, junction formation, metabolism, division, differentiation, metastasis and apoptosis. • To assay cell attachment, direct cell counting, time-lapse cinematograph and colorimetric methods have conventionally been used. • laborious, indirect and not time-resolved. • Ehret et al. designed an interdigitated microelectrode to obtain the impedance data attributable to cell physiological status,the interdigitated electrode design has merits of high cell constant and uniform sensing interval. • very reliable and informative.

4. 2.EXPERIMENTAL Schematic diagram of the impedimetric system:

5. 2.1. Impedimetric measuring chamber with microelectrodes • Interdigitated microelectrode plate (IMP, Fig. 1c) was patterned on a glass slide (26mm × 76mm; Fig. 1b) by the wet-etching process. • Cell chamber for impedimetric measurement was constructed by mounting and fixing a section of glass tube (12mm i.d. × 6 cm height) on the IMP plate using epoxy resin. (b) schematic diagram of the interdigitated microelectrode plate; (c) a photograph of MDCK cells grown on the microelectrode plate.

6. RGD-C peptide was adsorbed on the microelectrodes 1 mg/cm2 by dipped-coating procedure. 2.2. Culturing cells in the measuring chamber • MDCK cells (ATCC CCL-34, passages 50–90) were cultured in Dulbeco’s modified Eagle’s medium (DMEM) supplemented with 10% fetal bovine serum (GIBCO) and 5% gentamycin at 37 ◦C in ahumidified atmosphere of 5% CO2 and 95% air. 2.3. Impedance analyzing system • Time-resolved admittance spectra were obtained with a commercialized impedance analyzer (hp4194A). • The operating frequency was scanned from 1 kHz to 1MHz by 10 kHz increment, and the sampling interval was 1 min.

7. 3. Results and discussion Monitoring of admittance during cell attachment:

8. ` Determination of cell density using low-frequency conductance signal:

9. The following correlation equation was established from 30 experiments (Fig. 4) with different cell densities using chambers with bare microelectrodes: The following equation was established using chambers with electrodes coated with RGD-C peptide (n = 20; Fig. 4):

10. 4. Conclusions • Data obtained with the impedimetric system were informative for cell physiology and biomaterial studies. • Cell attaching/detaching process, formation of confluent layer, apoptosis and even migration phenomena might be resolved and quantified by the proposed system. • The study provided also a reliable protocol to determine the cell density attached onto the surface interested and also the timing of the attach process.