Enrichment method

A method for enriching extracellular DNA and sequentially extracellular vesicles and optionally extracellular RNA or for enriching extracellular vesicles and optionally extracellular RNA from a biological sample comprising extracellular DNA and extracellular vesicles, wherein the method comprises:

• (a) preparing a binding mixture comprising
• the biological sample,
• a solid phase comprising anion exchange groups, and
• an acidic binding buffer comprising a buffering agent,
• and binding extracellular DNA to the solid phase comprising anion exchange groups;
• (b) separating the solid phase with the bound extracellular DNA from the binding mixture to obtain a remaining binding mixture, wherein the remaining binding mixture comprises extracellular vesicles;
• and
• (c) processing the remaining binding mixture to enrich one or more biological targets of interest therefrom, wherein the processing comprises enriching extracellular vesicles and optionally extracellular RNA as biological targets of interest from the remaining binding mixture,
• wherein step (c) comprises enriching extracellular vesicles by binding to an anion exchange surface of a solid phase in the presence of a buffering agent,
• wherein the binding conditions used in step (a) for binding extracellular DNA differ from the binding conditions used in step (c) for binding extracellular vesicles and optionally extracellular RNA, and
• wherein the different binding conditions in step (a) and step (c) are achieved by at least one selected from the group consisting of:
• (i) the extracellular vesicle binding mixture of step (c) has a lower pH than the extracellular DNA binding mixture of step (a);
• (ii) the buffering agent introduced into the extracellular vesicle binding mixture in step (c) differs from the buffering agent in the extracellular DNA binding mixture in step (a) and (iii) the anion exchange surface of a solid phase in step (c) differs from the anion exchange groups of the solid phase in step (a).