Manipulation of cells with electric fields via addition of carbon nanoparticles

Abstract

Event Abstract Back to Event Manipulation of cells with electric fields via addition of carbon nanoparticles Fan-Yi Li1 and Yi-Chang Chung1 1 National University of Kaohsiung, Chemical and Materials Engineering, Taiwan In this study, we used polydopamine nanoparticles to prepare fluorescent carbon nanoparticles (CNPs). Using zwitterionic phosphatidylcholine (PC) molecules, we could control the sizes of polydopamine nanoparticles and increase their dispersion in water. We also developed a fast and safe hydrothermal microwave heating process to dehydrate the polydopamine nanoparticles into carbon nanoparticles. We investigated the effect of fluorescent carbon nanoparticles for dying cells in vitro, as well as the effect of PC on the carbon nanoparticles. Due to the polydopamine-derived CNPs having good electrical conductivity, we manipulated some cell uptake with conductive CNPs to observe the influence on cell attachment and growth under an electric field. In the characterization of physical properties of our CNPs, X-ray diffraction (XRD) patterns revealed the graphite structure of the polydopamine-prepared CNPs, and their Fourier transform infrared (FTIR) and UV-vis spectroscopic figures showed that the carbonized polydopamine nanoparticles retained polypeptide structures. Fluorescence spectroscopy was used to confirm the excitation of CNPs under UV irradiation. Pure CNPs and 1%-PC CNPs emitted a blue band light; while 10%-PC CNPs showed two bands, located in blue and green bands. Quinine sulfate solution was used as a calculation standard of fluorescent quantum efficiency and we could find that pure CNPs, 1%-PC CNPs, and 10%-PC CNPs displayed high fluorescence quantum efficiency of 21.4%, 20.3%, and 6.2%, respectively. According to observation of transmission electron microscopy (TEM) images, the sizes of pure CNPs, 1%-PC CNPs, and 10%-PC CNPs were 27±19 nm, 2±1 nm, and 7±2 nm, respectively, showing excellent dispersion in aqueous solution via addition of PC. In cell culture tests, L929 mouse fibroblasts were incubated with the three different kinds of CNPs to explore cell fluorescence images of the CNPs, showing that each kind could dye cells without fading even after a week of incubation. After cell co-culture for a period of 1 or 7 days, MTT assay tests revealed no cytotoxicity among those CNPs. Cell attachment measurements after electrical stimulation for one hour showed that the cell attachment numbers for cell uptake with CNPs were significantly different from those of the L929 cell control. Due to the good electrical conductivity of CNPs, the nanoparticles swallowed by cells seemed more easily attracted to the electric field. Therefore, CNP uptake can increase the attachment of cells onto a conductive plate electrode in a short time. When the source of the electric field was changed to rod electrodes in the medium, cells that had been pre-adsorbed onto a non-conductive plate were desorbed from the plate and destroyed. Therefore, addition of CNPs during cell incubation can allow control of cell growth and death via manipulation of electric fields. Ministry of Science and Technology, R.O.C.