It has surprisingly been discovered that it is possible to stabilize biomolecules such as RNA, DNA and proteins in biological samples such as cells, tissues, biopsies and blood using deep eutectic solvents (DES). It has also been discovered that DES mixtures can be used to fix and preserve cell morphology in biological samples such as tissue blocks, cancer biopsies and whole blood. This invention describes methods to stabilize and preserve biomolecules, whole cells, tissues, blood and biological samples using DES mixtures.