Preparation of lyophilized cells to preserve enzyme activities and high molecular weight nucleic acids

DNA from cells is required for many biotechnology and research applications, such as molecular cloning. To remove and purify DNA from cells, researchers use various methods of DNA extraction. While the specifics of different protocols may vary, some general concepts underlie the process of DNA extraction.

Tissue homogenization involves disintegrating tissue architecture and lysing cells, and is an early step in isolating and analyzing cellular components. The method used for homogenization depends on the sample type, the amount of sample available, the analyte to be obtained, and the sensitivity of the method. These methods are broadly classified as mechanical and non-mechanical methods.
Mechanical methods of tissue homogenization
These methods rely on applying external physical force to disrupt...

To be visualized by an electron microscope, either transmission or scanning, biological samples need to be fixed (stabilized) so the electron beam does not destroy them and dried thoroughly (desiccated/dehydrated) so the vacuum does not affect them. Fixation needs to be done as quickly as possible because the sample properties will start changing as soon as it is removed from its natural environment. For example, in a tissue sample, the oxygen levels begin decreasing, causing an altered...