Semi-Permeable Protocells Enable Direct Target Detection in Non-Purified Blood

In controlling the transport of molecules, many different types of size-selective membranes have been used in various applications, including water purification, electrolyte separation of batteries, and biological compartmentalization. In particular, regulation of molecular transport can be beneficial for biosensors; effective exclusion of fouling molecules can be directly linked to sensitive and selective detection of targets, even in complex body fluids. In this work, we explored the potential of semi-permeable protocells for point-of-care testing with no sample purification. Due to the small size, the membrane of the protocells can exclusively allow the entry of analytes with no access to nucleases and charged proteins, which would be an optimal environment for encapsulated DNA sensing probes. To this end, we first introduced the water-in-oil emulsion to construct the semi-permeable microcapsules composed of self-assembled protein-polymer amphiphiles. In the microstructure of the cross-linked membrane, newly designed aptasensors were subsequently enclosed to report the presence of various biomarkers via fluorescent signaling. We demonstrate that the aptasensor-encapsulated protocells achieve multiplexing real-time detection of estradiol, dopamine, and cocaine, even in undiluted blood and serum.