This invention is a method for improving electron microscopy image quality of a sample by increasing the electrical conductivity of the sample. The increased conductivity of the sample counteracts detrimental surface charging typically caused by electron microscopes. The method also increases the stability of the sample for higher quality serial sectioning.
A major limitation of using electron microscopy on biological samples is surface charging of the samples. Local accumulation of charge on the surface of a specimen sample can result in poor image quality and distortions, especially since most biological specimens are non-conductive. This invention is a method of counteracting the surface charging from an electron microscope by making the sample electrically conductive. The method dramatically increases tissue contrast as well as provides stability of cells and tissues for serial sectioning using ultramicrotomy.
This invention improves upon current techniques in electron microscopy, a key tool for investigating biological ultrastructure. This invention especially improves volume electron microscopy, such as serial section transmission electron microscopy (ss-TEM) and serial block-face scanning electron microscopy (SBF-SEM), as well as inelastically scattered electrons (energy-loss electrons, EELS), X-rays, and energy-dispersive X-ray spectroscopy (EDS).
How it works:
The method includes en bloc electron-conductive ionic liquid stain for volume electron microscopy. By utilizing a resin and an electrically conductive chemical, the method dramatically increases sample electrical conductivity as well as provides stability of cells and tissues for serial sectioning.
The novel method reduces sample surface charge, a major drawback in volume electron microscopy. As a result, the method increases the image contrast and reduces distortions typically caused by surface charging. Further, this technology provides stability of cell and tissue samples under the electron beam, allowing this technology to be used with not only SEM, but also inelastically scattered electrons (energy-loss electrons, EELS), X-rays, and EDS. Increased sample stability also allows for serial sectioning of the sample.
Why it is better:
This new method prevents sample surface charging, which results in better image quality. This method also increases the stability of samples, enabling them to be used for serial sectioning. Previous methods for increasing sample conductivity cause the samples to become brittle or even soft, making them difficult to serially cut using ultramicrotomy. The present invention, in contrast, allows the samples to withstand the extreme conditions of electron microscopy.