Fourier Transform Infrared spectroscopy discloses different types of cell death in flow cytometrically sorted cells.

Fourier Transform Infrared (FTIR) spectroscopy is a label free methodology showing promise in characterizing different types of cell death. Cervical adenocarcinoma (HeLa) and African monkey kidney (Vero) cells were treated with a necrosis inducer (methanol), novel apoptotic inducers (diphenylphosphino gold (I) complexes) and positive control, auranofin. Following treatment, cells stained with annexin-V and propidium iodide were sorted using a Fluorescence Activated Cell Sorter (FACS Aria) to obtain populations consisting of either viable, necrotic or apoptotic cells. Transmission Electron Microscopy confirmed successful sorting of all three populations. Four bands were identified which could discriminate between viable and necrotic cells namely 989 cm(-1), 2852 cm(-1), 2875 cm(-1) and 2923 cm(-1). In HeLa cells viable and induced apoptosis could be distinguished by 1294 cm(-1), while four bands were different in Vero cells namely; 1626 cm(-1), 1741 cm(-1), 2852 cm(-1) 2923 cm(-1). Principal Component Analysis showed separation between the different types of cell death and the loadings plots indicated an increase in an additional band at 1623 cm(-1) in dead cells. FTIR spectroscopy can be developed into an invaluable tool for the assessment of specific types of chemically induced cell death with notably different molecular signatures depending on whether the cells are cancerous and mechanism of cell death.

Cellular injury evidenced by impedance technology and infrared microspectroscopy.

Fourier Transform Infrared (FTIR) spectroscopy is finding increasing biological application, for example in the analysis of diseased tissues and cells, cell cycle studies and investigating the mechanisms of action of anticancer drugs. Cancer treatment studies routinely define the types of cell-drug responses as either total cell destruction by the drug (all cells die), moderate damage (cell deterioration where some cells survive) or reversible cell cycle arrest (cytostasis). In this study the loss of viability and related chemical stress experienced by cells treated with the medicinal plant, Plectranthus ciliatus, was investigated using real time cell electronic sensing (RT-CES) technology and FTIR microspectroscopy. The use of plants as medicines is well established and ethnobotany has proven that crude extracts can serve as treatments against various ailments. The aim of this study was to determine whether FTIR microspectroscopy would successfully distinguish between different types of cellular injury induced by a potentially anticancerous plant extract. Cervical adenocarcinoma (HeLa) cells were treated with a crude extract of Pciliatus and cells monitored using RT-CES to characterize the type of cellular responses induced. Cell populations were then investigated using FTIR microspectroscopy and statistically analysed using One-way Analysis of Variance (ANOVA) and Principal Component Analysis (PCA). The plant extract and a cancer drug control (actinomycin D) induced concentration dependent cellular responses ranging from nontoxic, cytostatic or cytotoxic. Thirteen spectral peaks (915cm(-)(1), 933cm(-)(1), 989cm(-)(1), 1192cm(-)(1), 1369cm(-)(1), 1437cm(-)(1), 1450cm(-)(1), 1546cm(-)(1), 1634cm(-)(1), 1679cm(-)(1) 1772cm(-)(1), 2874cm(-)(1) and 2962cm(-)(1)) associated with cytotoxicity were significantly (p value<0.05, one way ANOVA, Tukey test, Bonferroni) altered, while two of the bands were also indicative of early stress related responses. In PCA, poor separation between nontoxic and cytostatic responses was evident while clear separation was linked to cytotoxicity. RT-CES detected morphological changes as indicators of cell injury and could distinguish between viable, cytostatic and cytotoxic responses. FTIR microspectroscopy confirmed that cytostatic cells were viable and could still recover while also describing early cellular stress related responses on a molecular level.

The degree of polymerisation shrinkage of adhesive resin cements.

The degree of polymerisation (DP) of modern resin cements has a significant role to play in determining the ultimate physical and mechanical properties of the material. This study was undertaken to determine the DP of three adhesive resin cements, viz. 3M Opal Cement (3M), Enforce (E, Caulk/Dentsply) and C epsilon tB-Metabond (CB, Parkell). Spectra of both light-cured (3M and E) and self-cured (3M, E and CB) samples were obtained at different time intervals from 3 minutes after mixing the cement up to 24 hours, using a Dilor Raman Confocal Microprobe. The DP of the different cement specimens was calculated from the spectra and statistically analysed (ANOVA). There was a statistically significant difference (P < 0.01) between the DP of 3M and E in the two different activation modes. The light-cured specimens attained a statistically higher degree of polymerisation. CB obtained a statistically significant higher degree of polymerisation (P < 0.01) compared with 3M and E at 24 hours.

Percentage cure of cement cured through various thicknesses of Cerec porcelain.

Highly filled luting resins are recommended for bonding porcelain restorations to tooth structure. This in vitro investigation was undertaken to determine the degree of cure of a 82 per cent filled dual-curing luting resin, after it was cured through various thicknesses of Cerec Vita Mark II porcelain. Infrared, as well as micro-Raman spectroscopy were used to determine the degree of cure of the cement at different time intervals after mixing and exposure to the curing light. The results indicated that Cerec porcelain thicknesses greater than 3 mm adversely affected the degree of cure of the luting resin, even at 24 hours after mixing the cement.