This disclosure provides a method for substantially increasing the concentration of cfDNA in a patient. By injecting a patient with lipid and/or polymer nanoparticles, agents that bind cfDNA, or inhibit deoxyribonucleases prior to collection of a sample of cfDNA, e.g., by way of a liquid biopsy, major pathways for the degradation of cfDNA are temporarily blocked, permitting transient accumulation of cfDNA. This strategy has the potential to dramatically enhance the quality of detection achieved by downstream cfDNA e analytical applications, such as sequencing applications.