Investigation of lipid oxidation in freeze-dried membranes using Confocal Laser Scanning Microscopy
Special Symposium - Innovations in Food Technology (LMC Congress)
Innovations in Food Technology - Poster Session (Food - P2)
Keywords: microscopy, cell membranes
Conservation of biological systems including humane cells and bacteria by means of freeze drying is a promising tool. For the dairy industry freeze drying of lactic acid bacteria is very important in relation to stability during transportation and storage. In humane medicine preservation of viable cells by freeze drying is an important aspect when studying drug delivery e.g. in cancer treatment. However, during freeze drying and storage a number of factors may influence the membranes and impact their functionality following storage. Oxidation of membrane lipids seems to be involved in membrane deterioration, and oxidation mechanisms should accordingly be investigated in order to optimise the storage stability of freeze-dried membranes.
By incorporating a reporter molecule, an oxidation-sensitive fluorescent probe C11-BODIPY581/591 into living cells and model membranes it is possible to detect lipid oxidation at a cellular level (Drummen et al., 2002) However, application of this probe in freeze-dried membranes has not yet been explored. Upon oxidation fluorescence of the probe shifts from red to green, and Confocal Laser Scanning Microscopy (CLSM) can be used to visualise the oxidation in the intact cells.
Dry liposomes can be used as model systems for freeze-dried cell membrane lipids, and in the present study the fluorescent reporter molecule C11-BODIPY581/591 has been incorporated into freeze-dried liposomes. Fluorescent techniques were used to follow the oxidation of the probe (fluorescence spectroscopy and Confocal Laser Scanning Microscopy), while oxidation of the lipid was followed by measuring conjugated dienes. The results show that the probe can be used as a marker of oxidation in freeze-dried liposomes, and incorporation of the probe in other freeze-dried membranes including membrane structures of probiotic lactic acid bacteria will be a valuable tool to investigate cellular oxidation and improve vitality of this type of bacteria following storage in freeze-dried systems.
Drummen, GPC., van Liebergen, LCM., Op den Kamp, JAF. & Post, JA. (2002). C11-BODIPY581/591, an oxidation-sensitive fluorescent lipid peroxidation probe: (Micro)spectroscopic characterization and validation of methodology. Free Radical Biology & Medicine, Vol. 33, No. 4, pp. 473-490.
