Selenium nanoparticles (Se NPs) were prepared based on the reduction of selenious acid (H2SeO3), by employing sodium alginate (SA) as a template. The real-time monitoring of the drug-inducing apoptosis process of human hepatic cancer cells Bel7402 was performed with the quartz crystal microbalance (QCM) measurement. The anti-tumor effect of adriamycin (ADM) used in combination with Se NPs was investigated. It is found that both drugs were able to inhibit cell proliferation in a dose-dependent way and the combined treatment with ADM and Se NPs was more effective in inhibiting cell growth than each of the two drugs alone. The cytotoxic effects of drug combination were evaluated with the modified Bürgi formula (Jin equation) based the Δf0 responses. The grades gradually changed from apparent synergism to simple addition with the drug-treatment time increasing but the drug combination with lower concentrations still exhibited synergism after 24 h, suggesting a potential application in cancer therapy.

The processes of adhesion, spreading and proliferation of human mammary cancer cells MCF-7 on two Au electrodes with different surface roughness (Rf and Rf = 3.2 or 1.1) were monitored and clearly identified with the quartz crystal microbalance (QCM) technique. Analyses of the QCM responses on the resonant frequency shifts (Δf0) vs. the motional resistance changes (ΔR1) revealed a significant surface-stress effect in the involved courses, in addition to a viscodensity effect and a relatively small mass effect (especially at the smooth electrode). Experiments of fluorescence microscopy, cyclic voltammetry and electrochemical impedance spectroscopy were conducted to investigate the cell population on the electrode vs. the electrode-surface roughness. Simplified equations are deduced to quantitatively evaluate the surface stress, and a novel QCM method for dynamically measuring the surface stress on an electrode in cell-culture course is thus described. It was found that the smoother surface (Rf = 1.1) gave a higher surface stress during cell attachment and less cell population on it than the rougher surface (Rf = 3.2). In addition, real-time QCM monitoring showed on the same electrode the surface stress induced by hepatic normal cells being notably higher than that caused by hepatic cancer cells at cell-attachment stage, suggesting that the surface-stress measurement can exhibit the difference of adhesion-performance between the healthy and ill-behaved cells.

The real-time monitoring of the agglutination process of human hepatic normal cells (L-02) at the quartz crystal microbalance (QCM) gold (Au) electrode was performed. Two lectins, concanavalin A (Con A) and wheat germ agglutinin (WGA), induced the cell agglutination, resulting in the different Δf0 and ΔR1 responses from those caused by the normal cell attachment and growth. The cell–Con A–cell aggregates had higher affinity for the Au substrate due to the excellent adsorption ability of Con A, which was revealed by increased Δf0 and ΔR1 shifts and the obvious mass effect of QCM. In contrast, the lower adsorption ability of cell–WGA–cell aggregates was related to the same characteristic of WGA, presenting the decreased Δf0 and ΔR1 responses and the time-extended adhesion phase. Parallel microscopic observation experiments were also carried out and exhibited comparable results. The Δf0 responses during the processes of cell growth and cell agglutination were analyzed using the equations Δf0=a0+a1e-t/τ1+a2e-t/τ2+a3e-t/τ3Δf0=a0+a1e-t/τ1+a2e-t/τ2+a3e-t/τ3 and Δf0=a0+a1e-t/τ1+a2e-t/τ2Δf0=a0+a1e-t/τ1+a2e-t/τ2, respectively. Furthermore, the current work proved that the QCM measurement technique based on cell agglutination was useful for discriminating hepatic normal cells (L-02) and hepatic cancer cells (Bel7402).