Porous PDMS‐Based Microsystem (ExoSponge) for Rapid Cost‐Effective Tumor Extracellular Vesicle Isolation and Mass Spectrometry‐Based Metabolic Biomarker Screening

Abstract Polydimethylsiloxane (PDMS) is an inexpensive robust polymer that is commonly used as the fundamental fabrication material for soft‐lithography‐based microfluidic devices. Owing to its versatile material properties, there are some attempts to use PDMS as a porous 3D structure for sensing. However, reliable and easy fabrication has been challenging along with the inherent hydrophobic nature of PDMS hindering its use in biomedical sensing applications. Herein, a cleanroom‐free inexpensive method to create 3D porous PDMS structures, “ExoSponge” and the effective surface modification to functionalize its 3D porous structure is reported. The ability of ExoSponge to recover cancer‐associated extracellular vesicles (EVs) from complex biological samples of up to 10 mL in volume is demonstrated. When compared to ultracentrifugation, the ExoSponge showes a significant increase in cancer EV isolation of more than 210%. Targeted ultra‐high pressure liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) is further employed to profile 70 metabolites in the EVs recovered from the lung cancer patient's plasma. The resulting profiles reveal the potential intraexosomal metabolite biomarker, phenylacetylglutamine (PAG), in non‐small cell lung cancer. The high sensitivity, simple usage, and cost‐effectiveness of the ExoSponge platform creates huge potential for rapid, economical and yet specific isolation of exosomes enabling future diagnostic applications of EVs in cancers.