Single MCF-7 Cells Research Articles

Quantification of Bax protein on tumor cells based on electrochemical immunoassay

Bax protein is a pro-apoptotic member of Bcl-2 family proteins on cells and exhibits a close relationship with drug resistance of tumor cells. Its quantification can provide significant information for cancer treatment and research. A valid and sensitive electrochemical method for quantitative analysis of Bax protein on tumor cells was developed using thionine–graphene composites (TH–GN) based on a competitive immunoreaction. Bax protein and horseradish peroxidase were assembled on the TH–GN modified electrode to construct an electrochemical biosensor. The binding of Bax antibody could decrease the responses of the developed biosensor due to the strong steric hindrance effect and this effect was weakened in the presence of tumor cells or free Bax protein. Under optimal conditions the peak current change derived from the differential pulse voltammetry (DPV) measurements (ΔIDPV) was proportional to the cell concentration from 2.5×103 to 1.6×105cellsmL−1 with a detection limit of 800cellsmL−1. The average amount of Bax protein on single MCF-7 cell and MCF-7/ADR cell were calculated to be (1.2±0.2)×1011 molecules and (7.2±1.1)×1010 molecules, respectively. It indicates that the decrease of Bax protein is one of important reasons resulting in drug resistance of tumor cells.

High density CMOS electrode array for high-throughput and automated cell counting

A high-density electrical-impedance spectroscopy (EIS) biosensor array has been developed for high-throughput and automated counting of specific breast tumor MCF-7 cells. The biosensor array (96×96) consists of densely packed electrodes. Each of the square electrodes has an edge-length of 22μm to capture single MCF-7 cell. The electrodes are electrically addressable by decoding circuit built underneath by 0.18μm CMOS process. EIS spectra of electrodes were recorded over a wide frequency range with and without the presence of cell. Data were numerically fitted with the equivalent circuit model to extract important sensing parameters including cell impedance, electrode impedance, sealing resistance and spreading resistance. Results revealed a distinctive impedance increase from 50kHz to 500kHz, where the maximum (∼21% increment) occurs at 200kHz. Enumeration of circulating tumor cells (CTCs) was performed by scanning an interrogation area of hundred electrodes at the optimum frequency. The developed EIS platform has demonstrated the electrical impedance detection with single cell resolution and enumeration with mapping accuracy of ∼90%.

Single HeLa and MCF-7 cell measurement using minimized impedance spectroscopy and microfluidic device

This study presents an impedance measurement system for single-cell capture and measurement. The microwell structure which utilizes nDEP force is used to single-cell capture and a minimized impedance spectroscopy which includes a power supply chip, an impedance measurement chip and a USB microcontroller chip is used to single-cell impedance measurement. To improve the measurement accuracy of the proposed system, Biquadratic fitting is used in this study. The measurement accuracy and reliability of the proposed system are compared to those of a conventional precision impedance analyzer. Moreover, a stable material, latex beads, is used to study the impedance measurement using the minimized impedance spectroscopy with cell-trapping device. Finally, the proposed system is used to measure the impedance of HeLa cells and MCF-7 cells. The impedance of single HeLa cells decreased from 9.55 × 10(3) to 3.36 × 10(3) Ω and the impedance of single MCF-7 cells decreased from 3.48 × 10(3) to 1.45 × 10(3) Ω at an operate voltage of 0.5 V when the excitation frequency was increased from 11 to 101 kHz. The results demonstrate that the proposed impedance measurement system successfully distinguishes HeLa cells and MCF-7 cells.

Surface-enhanced Raman scattering imaging of HER2 cancer markers overexpressed in single MCF7 cells using antibody conjugated hollow gold nanospheres

Antibody-conjugated hollow gold nanospheres (HGNs) have been used for the SERS imaging of HER2 cancer markers overexpressed in single MCF7 cells. SERS mapping images show that HGNs have much better homogeneous scattering properties than silver nanoparticles. The results demonstrate the potential feasibility of HGNs as highly sensitive and homogeneous sensing probes for biological imaging of cancer markers in live cells.

Cell cycle‐dependent characterization of single MCF‐7 breast cancer cells by 2‐D CE

The composition of single MCF-7 breast cancer cells is characterized using 2-D CE. Individual MCF-7 cells were aspirated into a 30 mum inner diameter fused-silica capillary and lysed by contact with an SDS-containing buffer. Proteins and other primary amines were fluorescently labeled on-column using the fluorogenic dye 3-(2-furoyl)quinoline-2-carboxaldehyde. Labeled components were separated first according to molecular weight using capillary sieving electrophoresis (CSE) and then by MEKC. Analytes were detected in a sheath-flow cuvette using LIF. The expression profiles for MCF-7 cellular homogenate and a single MCF-7 cell are compared. As a proof-of-principle investigation, variation in expression was also compared within and between G1 and G2/M cell cycle phases for MCF-7 cells. Following their treatment with the viable nuclear stain Hoechst 33342, MCF-7 cells were sorted by flow cytometry on the basis of their ploidy. Sorted cells were then analyzed by 2-D CE. The degree of variability was >2.5 times larger between cells of different phases than between cells of the same phase. In typical 1 h 2-D CE separations using MCF-7 cells, over 100 components are resolved.