Cell Isolation and Recovery Using Hollow Glass Microspheres Coated with Nanolayered Films for Applications in Resource-Limited Settings

Established cell isolation and purification techniques such as fluorescence-activated cell sorting (FACS), isolation through magnetic micro/nanoparticles, and recovery via microfluidic devices have limited application as disposable technologies appropriate for point-of-care use in remote areas where lab equipment as well as electrical, magnetic, and optical sources are restricted. We report a simple yet effective method for cell isolation and recovery that requires neither specialized lab equipment nor any form of power source. Specifically, self-floating hollow glass microspheres were coated with an enzymatically degradable nanolayered film and conjugated with antibodies to allow both fast capture and release of subpopulations of cells from a cell mixture. Targeted cells were captured by the microspheres and allowed to float to the top of the hosting liquid, thereby isolating targeted cells. To minimize nonspecific adhesion of untargeted cells and to enhance the purity of the isolated cell population, an antifouling polymer brush layer was grafted onto the nanolayered film. Using the EpCAM-expressing cancer cell line PC-3 in blood as a model system, we have demonstrated the isolation and recovery of cancer cells without compromising cell viability or proliferative potential. The whole process takes less than 1 h. To support the rational extension of this platform technology, we introduce extensive characterization of the critical design parameters: film formation and degradation, grafting with a poly(ethylene glycol) (PEG) sheath, and introducing functional antibodies. Our approach is expected to overcome practical hurdles and provide viable targeted cells for downstream analyses in resource-limited settings.