New treatments are urgently required for osteosarcoma, a type of cancer that starts in the bones and mainly occurs in children and teenagers. Current treatments mostly rely on DNA-damaging agents such as cisplatin, which was the first platinum-based anti-cancer metallodrug, introduced in the clinics in the 1970s.
However, the in vivo anticancer activity of cisplatin is severely limited by low bioavailability, serious side effects and acquired resistance. In order to enhance its effectiveness and improve patient outcomes, a better understanding of how the drug works - particularly at the cellular and subcellular levels - is crucial.
Previous studies using synchrotron-based Fourier Transform IR microspectroscopy (SR micro-FTIR), micro-Raman and inelastic neutron scattering (INS) offered insights into the drug’s metabolic effect, and the cellular response to treatment. However, these techniques did not provide a high enough spatial resolution to allow an accurate examination of the drug´s effect on specific sub-cellular regions. In work recently published in in Scientific Reports, researchers from the University of Coimbra (Portugal), in collaboration with beamline B22 staff, used synchrotron-based infrared nanospectroscopy (SR nano-FTIR) at Diamond to reveal the action of a consolidated metallodrug at the subcellular scale. Their study is the first life sciences application of scattering-Scanning Near-field Optical Microscopy (s-SNOM) at Diamond and is expected to foster the development of novel metal-based chemotherapeutic agents against osteosarcoma.
In s-SNOM, an Atomic Force Microscope (AFM) tip is used to confine and focus the IR light interaction on a sub-micron scale. When the tip is brought very close to the sample surface, the IR light probes the sample in the near-field region. The scattered light can then be detected and contains information about the sample's local optical properties. IR Nanospectroscopy (nano-FTIR) combines s-SNOM with infrared illumination and FTIR-based spectroscopy. The technique overcomes the resolution limits of micro-FTIR spectroscopy, providing the label-free chemical analysis capability of FTIR coupled to the extremely high spatial resolution given by s-SNOM. The broad spectrum and brightness of synchrotron IR radiation turns it into a powerful tool for spectral mapping of tissue and cellular constituents, providing both morphological and biochemical information in the same experiment at the 100 nanometre spatial scale.
"This is a new technique on the B22 beamline," says Senior Support Scientist Dr Hendrik Vondracek, "and this was the first biological experiment on this new setup. It allows researchers to get insights into the subcellular chemical information on mammalian cells, which is something that's not easy to achieve with other methods. We came up with a clustering approach that allows us to detect changes on the subcellular level without having to rely on a single point spectrum. That's a big leap in the method that allows a more detailed insight into the cell metabolism."
During these experiments, the team carried out synchrotron nano-FTIR measurements on cisplatin-exposed human osteosarcoma cells as well as on drug-free (control) cells. This method allows topography, mechanical response and optical images to be obtained simultaneously, in this case revealing a high sub-cellular heterogeneity at the nanometre scale. The data show well resolved cell topography and organelle contours, and the nano-FTIR spectra revealed the impact of cisplatin on cellular proteins, lipids and DNA.
The new information gathered during these experiments adds to data previously obtained on different scales using micro-FTIR and THz spectroscopies, together with micro-Raman and neutron scattering methods (both inelastic and quasi-elastic). By adding subcellular-level insight on the effect of the drug on specific cellular regions and biochemical components, it goes a step further, demonstrating the potential for using synchrotron nano-FTIR as a suitable nanospectroscopy probe in biomedical research. This new approach to studying the mode of action of metallodrugs at a molecular and subcellular level will be a key tool in the development of improved anticancer agents, potentially leading to improved clinical outcomes and a better quality of life for oncology patients.
IR nanospectroscopy also has applications beyond biological sciences, including materials science and condensed matter systems. Users who responded to the first call for proposals will begin conducting their experiments shortly, with a second collaborative call scheduled for the end of this year (2024).
To find out more about the B22 beamline or discuss potential applications, please contact Principal Beamline Scientist Dr Gianfelice Cinque: gianfelice.cinque@diamond.ac.uk.
Batista de Carvalho LAE et al. Synchrotron nano-FTIR spectroscopy for probing anticancer drugs at subcellular scale. Scientific Reports 14.1 (2024): 17166. DOI:10.1038/s41598-024-67386-y
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