The cell metabolism and its link to oncogenic signaling pathways have got significant interest due to their importance in cancer cell analysis, anticancer drugs development, spectroscopic micro imaging of human organs and tissues and many other biomedical applications. But the lack of advanced analytical tools for the investigation of living cell metabolism is still a challenge to be faced.

Since NMR spectroscopy is a reliable analytical method which gives comprehensive and rich chemical information about the composition of unknown materials and in the same time is a nondestructive technique and high speciation performance, it is one of the major technologies for metabolic profiling, hence allows in vitro and in vivo measurements of biological cells.

Typical NMR measurements are carried out in a cylindrical 5 mm tubes with approximately 700 μL sample, but measuring small and ultra-smaller samples volumes are not possible due to the limit of detection (LOD). Moreover, ensuring the viability and the proper living condition of cancer cell using the traditional NMR detectors is critical.

We designed and fabricated a novel miniaturized planer waveguide microslot NMR detector with on-board thermal regulator integrated with a microfluidic device. A tumour spheroid in a size of a few hundred μm diameter has been studied noninvasively and in a real time investigation mode. Moreover, the NMR spectra of cellular metabolites samples fall in the 100 pmol range were obtained with this microprobe in few minutes. Additionally, the planar geometry of the detector is suitable to the size and geometry requirements such different kind of microfluidic cellular sample holders for future studies such as bio-reactors.

In our research, we focus on metabolic analysis of production\degradation rates of living human cancer cells by using the Nuclear Magnetic Resonance (NMR) of different nuclei, which give direct evidence of the present status of the cell. A dual task cellular microfluidic NMR sample holder was designed with thermal and proper gas atmosphere controlled environment in order to maintain the viability of the studied living cells at near physiological conditions for the long-term in vitro studies and the hyphenation with adaptable lab on a chip technology.

Based on the developed NMR detector and the microfluidic chip, the dynamic processes of production and degradation of 23 cellular metabolites were monitored. Remarkably high concentrations of lactate and alanine were observed, being an indicator for a shift from oxidative to glycolytic metabolism. This distinctive development has proven to be a successful analytical tool for the elucidation of cellular functions and their corresponding biochemical pathways.

In our other investigation stream, living cancer cells is treated with metal based anti-cancer drugs (such as platinum based drugs); the metabolomics respond analyses combined with the (1H, 195Pt) NMR signals and correlation times will be employed to define the mechanism of anticancer drugs action and the molecular intra and extra cellular transport mechanism, by analysing quantities of the organic and inorganic 195Pt NMR signal beside the NMR chemical shifts.


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