Thermoresponsive polymer integrated metasurface sensor for capture and release of extracellular vesicles in real-time

Abstract

Extracellular vesicles (EVs) play pivotal tasks in intracellular communication, carrying biomolecules such as proteins, lipids, and nucleic acids that reflect the physiological state of their originating cells. Isolating EVs purely from complex and protein-rich matrixes is crucial for understanding cellular processes and disease progression. The gold standard method for isolating EVs is ultracentrifugation, yet it has severe obstacles in terms of requiring expensive equipment, non-vesicular impurities, and possible damage on the EV surface. Owing to these drawbacks, their further analyses, isolation and detection through their surface markers are challenging. This study aims to integrate a smart thermoresponsive polymer with a metasurface plasmonic sensor, which is further decorated with anti-CD63 antibodies to capture EVs derived from MCF-7 breast cancer cells as a model system. We later isolate (release) these EVs by simply altering the local temperature above the lower critical temperature (LCST) of the polymer. Basically, the thermoresponsive polymer exhibits hydrophilic characteristics below its LCST and becomes hydrophobic when the temperature is increased above the LCST. The optic plasmonic sensor has a well-defined nanoperiodic array, presenting surface plasmons while exciting the surface with a normal angle of incident light. Therefore, the metamaterial sensor denotes real-time and label-free detection of EV binding and release events. This enables the quantitative analysis of EVs. In a nutshell, leveraging the distinctive thermoresponsive characteristics of the polymer, we presented a novel methodology designed to selectively immobilize EVs through antibody interactions and subsequently release them by elevating the temperature. This process enables the isolation of EVs with a high degree of purity, free from non-specific molecular contaminants. Consequently, our pioneering approach opens a promising new way for studying EVs and their surface markers in great detail, unrestricted by the limitations of conventional separation techniques, and contributes to the understanding of complex cellular processes and the subtle development of illnesses.