Hyen-Wook Kang

Monitoring of cultured cell activity by the quartz crystal and the micro CCD camera under chemical stressors

For investigating effects of chemical stressors to cultured cells, we have developed a quartz crystal microbalance (QCM) system with a micro CCD camera that enables microscopic observations simultaneously with the QCM measurements. Human hepatoma cell line (HepG2) cells were cultured on the collagen coated quartz crystal which has indium tin oxide (ITO) electrodes that enable transmission imaging of the cultured cells by the micro CCD camera during the QCM measurements. Glutaraldehyde (GA) and t-butylhydroperoxide (t-BHP) were used for the chemical stressors. The response of the QCM was monitored and analyzed with the resonance frequency and the resonance resistance (F-R) diagram. At the same time, the photographs of the cells were recorded to observe the morphological change. In the case of GA, the QCM responded in two steps which consisted of the rapid response of the cross-linking reactions and successive decreasing cytoskeletons in the cells. In the case of t-BHP, the response showed two steps. At first, the cells changed their shapes to round, and then the weakened cells were unsticked from the surface.

Monitoring of morphology and physical properties of cultured cells using a micro camera and a quartz crystal with transparent indium tin oxide electrodes after injections of glutaraldehyde and trypsin

For investigating the effects of chemical stimulation to cultured cells, we have developed a quartz crystal sensor system with a micro charge-coupled device (CCD) camera that enables microphotograph imaging simultaneously with quartz crystal measurement. Human hepatoma cell line (HepG2) cells were cultured on the quartz crystal through a collagen film. The electrode of the quartz crystal was made of indium tin oxide (ITO) transparent electrodes that enable to obtain a transparent mode photograph. Glutaraldehyde and trypsin were injected to the chamber of the cells, respectively. The response of the quartz crystal was monitored and microphotographs were recorded, and the resonance frequency and resonance resistance were analyzed with an F-R diagram that plotted the resonance frequency and resonance resistance. In the case of the glutaraldehyde injection, the cells responded in two steps that included the fast response of the cross-linking reaction and the successive internal change in the cells. In the case of the trypsin injection, the responses included two processes. In the first step, cell adhesion factors were cleaved and the cell structure became round, and in the next step, the cells were deposited on the quartz crystal surface and the surface of the cells was directly in contact with the quartz crystal surface.

Monitoring of anticancer effect of cisplatin and 5-fluorouracil on HepG2 cells by quartz crystal microbalance and micro CCD camera

We have developed a monitoring system for evaluating the effect of anticancer agents, such as cisplatin and 5-fluorouracil (5-FU). The system mainly consisted of a quartz crystal microbalance (QCM) with indium tin oxide (ITO) electrodes and a micro CCD camera that can function in a humid CO(2) incubator. Human hepatoma cell line HepG2 cells were cultured and treated with the anticancer agents. As the behavior on the resonance frequency (F)-resonance resistance (R) diagram shows the viscoelastic change on the surface of the QCM, the effect of the anticancer agent was evaluated with the F-R diagram and the micro CCD camera, in comparison with the results in the case of general culturing (no anticancer agent injection). During general culturing, the resonance frequency decreased and the resonance resistance increased. This means that the mass loading of a viscous material occurred on the QCM. Observing with the micro CCD camera, the cancer cells were spread, divided, and the number of the cells increased. On the other hand, when the anticancer agent was injected to the culturing cancer cells, the resonance frequency and the resonance resistance increased continuously. This means a decrement of the mass effect and an increment of the viscosity on the QCM. From the observation with the micro CCD camera, the number of the cells did not change. The cells shrinked and changed the shape flat to round by loosing the cell activity in the case of 5-FU treatment. These results indicate the anticancer agents were effective to the culturing cancer cells.

Liquid Crystal Alignment Behavior on Rubbed Films of Cellulose Acetate

ABSTRACT The liquid crystal (LC) alignment behaviors of LC cells fabricated with cellulose acetate films were investigated. These polymer films exhibited good optical transparency in the visible light region (400–700 nm). For example, transmittance value (92%) of the cellulose acetate film onto glass substrate at 550 nm is better that (89%) of the polyimide (PI) film, the most commonly used LC alignment layers. These LC cells fabricated with the rubbed cellulose acetate films showed the homogeneous planar LC alignment with parallel direction with respect to the rubbing direction. The electro-optical characteristics of the LC cells made from the cellulose acetate films such as response time were as good as those fabricated from rubbed PI films.

Investigation of the Extracellular Matrix Effect for the QCM/CCD Cell Activity Monitoring System

A real-time quartz crystal microbalance (QCM) cell activity monitoring system coupled with micro CCD cameras was developed to investigate the cultured cell activity, which could measure the viscoelastic characteristics of the cell with the QCM and observe the cell morphology changes with CCD camera simultaneously. Both the viscoelastic characteristics and the shape of the cultured cell are important factors to estimate the cell activity and the cell adhesion. The extracellular matrix (ECM) on the surface of the QCM is essential to culture the cell stably in the QCM monitoring system. To find the ECM optimization condition, the adhesive strength of cultured cells on the ECM modified glass surface was measured by using rotating water stream and CCD camera. After culturing HepG2 cells for 24 hours on the ECM modified glass plates, the glass plates were dipped in the PBS solution and rotated with 1,000, 1,300, and 1,500 rpm for 30 seconds. The adhesiveness of ECMs was investigated by calculating the remained cells after rotating. Four types of ECM, such as amino group, carboxyl group, collagen monomer, and collagen polymer, were used and tested. The current paper improves the sensing system of previous report so that measurements of four ECMs can be simultaneously conducted under the same conditions in order to enhance reliability. A collagen polymer exposed ECM was the most stable on an adhesiveness point of view, but not suitable for the QCM cell activity monitoring due to the decrease of the QCM sensitivity. The sensitivity of the QCM cell activity monitoring system using collagen monomer as ECM is about 2.6 times better than that using collagen polymer. A collagen monomer exposed ECM was more stable than amino group and carboxyl group exposed ECMs based on an adhesiveness point of view. Therefore, a collagen monomer exposed ECM was the most stable and suitable for the QCM cell activity monitoring system among the four ECMs. The changes of the resonance frequency and the resonance resistance of the ECM film with the cultured cells were investigated and compared the results of CCD camera images. From these results, we showed the QCM cell activity monitoring system coupled with the micro CCD camera could be applied to the evaluation of the cell activities.

Evaluation of anticancer effect using quartz crystal microbalance and micro CCD camera

We have developed a monitoring system for evaluating the effect of anticancer agent, such as cisplatin and 5-fluorouracil (5-FU). The system mainly consisted of a quartz crystal microbalance (QCM) and a micro CCD camera that can function in a CO2 incubator. As the behavior on the resonance frequency (F) — resonance resistance (R) diagram shows the viscoelastic change on the surface of the QCM, the effect of the anticancer agent was evaluated with the F-R diagram and the micro CCD camera, in comparison with the results in the case of general culturing (no anticancer agent injection). During general culturing, the resonance frequency decreased and the resonance resistance increased. This means that the mass loading of a viscous material occurred. Observing with the micro CCD camera, the cells were spread, divided, and the number of the cells increased. On the other hand, when the anticancer agent was injected to the cancer cells, the resonance frequency and the resonance resistance increased gradually. This means the decrement of the mass effect and the increment of the viscosity on the QCM. By observation with the micro CCD camera, the number of the cells did not change. The cells shrinked and changed the shape flat to round by loosing the cell activity.

Fabrication of long tip AFM probes for highly coarse samples

A long polymeric tip has been fabricated for AFM measurements, which is able to image large and highly coarse objects such as biological and food samples. Two-photon adsorbed photo-polymerization technique provides a long polymeric tip onto a commercial cantilever. The length of the long polymeric tip was 90µm. Brown rice flours with ∼3µm diameter were imaged using the fabricated long tip. The result AFM image clearly showed coarse surface, which cannot be approached by a commercial tip. Since the fabricated tip has conical structure, a clear image of brown rice flours were achieved without sharp cliff-like patterns, which imaged by the commercial pyramidal shape tip.

Study on Electrical Phenomena Properties of Bio-lipid Film on Water Surface for Application of Medical Engineering Device

Monolayers of lipids on a water surface have attracted much interest as models of biological membranes, but also as precursors of multilayer systems promising many technical applications. They exhibit very interesting physico-chemical properties as two-dimensional and interfacial systems. Until now, many potential methodologies have been developed in order to gain a better understanding of the relationship between the structure and function of the monolayers.

Electrical Features of Surface Structure in Polymer Monolayers by Smm

Abstract Recent development in scanning probe microscope techniques has made it possible to investigate, not only microscopic surface topography, but also physical and chemical properties on the nanometer-scale. We observed the surface potential distribution and molecular ordering in monolayers. The SMM surface potential image clearly shows the existence of micron-sized domains in the polymer monolayers with a good correspondence to the topographical features. This is a first step towards understanding electrical phenomena in organic and inorganic materials with SMM.

The fabrication of gas sensor using the resonant frequency and admittance of quartz crystal analyzer

The adsorption and desorption behavior of organic vapours for polymeric sensitive LB film was investigated using the resonant frequency and resistance method of a quartz crystal microbalance. A new method was used to analyze the response mechanism between organic vapours and polymeric sensitive LB films. When the organic vapours were adsorbed into sensitive LB films, the rheological changes in LB films were observed by the quartz microbalance resonant method. To investigate the characteristics of organic vapours, a resonant frequency-resonant resistance (F-R) diagram was used. The quantitative information about organic vapours adsorbed and quantitative change of sensitive LB films can be obtained. In experimental results, the response of organic vapours can be separated into two types; surface adsorption and penetration into sensitive LB films. The response mechanism between organic vapours and sensitive LB films can be obtained from the F-R diagram.