Optical near-field analysis of biostructures in aqueous solutions: problems and proposals

Summary form only given. The cellular mechanisms relating to the accumulation and metabolism of estrogens (e.g. 17/spl beta/-Estradiol, E/sub 2/) are gaining in significance for the diagnostics and therapy of mamma carcinoma. The classical mechanism of the intracellular E/sub 2/ action is described as the regulation of DNA transcription and protein synthesis via E/sub 2/-specific receptors. Investigations on the accumulation kinetics of estrogens have to be performed on vital cells in aqueous environments. The optical properties of E/sub 2/ and E/sub 2/-induced cell reactions were first analysed by confocal laser scan microscopy However no E/sub 2/ specific intracellular fluorescence was detected. When a laser phase microscope (LPM) was used differences of the intensity profiles of the phase shifts were measured in single cells exposed to E/sub 2/ compared to control cells. Although the LPM method indicated metabolic changes on a nanoscale, the results were ambiguous since the phase shifts were influenced by refractive indices as well as the cell morphology. Cell structures can also change during metabolic processes.