Methods and systems for preparing and preserving biological samples are disclosed herein. A method comprises contacting a preserving agent with a biological sample to form a mixture, wherein the preserving agent is selected from at least one of a metal-organic framework (MOF) encapsulant or a precursor forming a MOF encapsulant, and wherein the biological sample comprises at least one target analyte. A system comprises a preserving agent selected from at least one of a metal-organic framework (MOF) encapsulant or a precursor forming a MOF encapsulant; and a substrate configured to receive a drop cast mixture of the preserving agent and a biological sample, wherein the biological sample comprises at least one target analyte.