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SIMS microscopy: methodology, problems and perspectives in mapping drugs and nuclear medicine compounds
1Service de Médecine Nucléaire et de Biophysique, Faculté Necker Enfants-Malades, Paris, France.
Cell Biology International
|August 7, 1998
Summary
Secondary ion mass spectrometry (SIMS) microscopy offers high sensitivity and resolution for biomedical research. This review highlights SIMS applications in drug mapping and physiological studies, emphasizing sample preparation and biological models.
Area of Science:
- Biomedical research
- Analytical chemistry
- Microscopy
Background:
- Secondary ion mass spectrometry (SIMS) is a powerful analytical technique developed in the 1960s.
- SIMS provides high sensitivity (ppm to ppb), specificity, and improved lateral resolution for biological samples.
- Understanding physiological and biomedical questions requires careful consideration of biological models and sample preparation.
Purpose of the Study:
- To review the capabilities and applications of SIMS microscopy in biomedical research.
- To discuss critical aspects of sample preparation, including cryogenic procedures and chemical fixation.
- To highlight SIMS utility in drug mapping and assessing the targeting specificity of pharmaceuticals.
Main Methods:
- Cryogenic procedures such as flash-freeze fixation, freeze-fracture, and cryoembedding are essential for analyzing diffusible ions.
- Scanning procedures and small probe sizes (below 50 nm) enhance lateral resolution for applications like chromosome imaging.
- Labeling with isotopes (halogens, 15N, 14C) or using time-of-flight SIMS (TOF-SIMS) facilitates drug detection and molecular imaging.
Main Results:
- SIMS enables cellular integrity checks by mapping major element distributions.
- Absolute quantification is achievable using internal references in embedded specimens.
- SIMS has demonstrated utility in assessing the in vivo targeting specificity of nuclear medicine agents.
- Microscopic evidence of thionamide-induced blockade of iodine organification in a human sample was presented.
Conclusions:
- SIMS microscopy is a valuable tool for detailed physiological and biomedical investigations.
- Appropriate sample preparation, particularly cryogenic methods, is crucial for accurate SIMS analysis of biological samples.
- SIMS applications extend to drug distribution studies and understanding therapeutic mechanisms, including a novel finding on iodine metabolism.