The goal of the proposed work is to develop a multistage cell separation technique to overcome selectivity problems caused by non-specific interactions using temperature-sensitive polymers and multiple temperature cycling. A simple and rapid method for separation of cells is to functionalize magnetic particles (MNPs) with a receptor that selectively captures the target and then remove the MNPs from the mixture by applying a magnetic field. The efficiency of magnetic separation is typically limited by the non-specific interaction between the MNPs and non-target species. To overcome the inefficiencies caused by non-specific interactions in current single-stage magnetic separation techniques, the PI aims to develop a multistage cell separation technique that is analogous to multistage distillation. The key idea is to allow the MNPs capture and release the target cells by manipulating the hydrophobic interaction between the MNPs and the cells. This process will be enabled by attaching temperature-responsive polymers to both the MNPs and the target cells. Through temperature cycling, which triggers the reversible hydrophilic-to-hydrophobic phase transition of the polymers, the target cells can be reversibly captured and released by the MNPs (due to hydrophobic interaction) at a higher efficiency than the non-target cells. The difference in the capture-and-release efficiencies of target cells versus non-target cells in a single cycle will be amplified by multiple separation stages. The hypothesis is that a multistage separation process will be able to effectively circumvent the problem caused by the non-specific interactions in the current single-stage magnetic cell separation process. The PI will (i) construct a platform to realize the proposed multistage cell separation scheme, (ii) test the hypothesis that this scheme is able to overcome the inefficiencies caused by non-specific interactions, and (iii) develop general principles for designing multistage cell separation processes, guided modeling tools developed for multistage distillation processes. Broader Impacts. The proposed technology may find applications in medical diagnostics and therapeutics, environmental monitoring, and homeland security. As part of the educational mission, this project will integrate research and education by (i) providing training for graduate and undergraduate students at the crossroads of chemical engineering, materials and surface science, and biochemistry, (ii) developing new materials for the multistage separation course in chemical engineering education, highlighting possible innovations by applying established chemical engineering principles to emerging fields, (iii) increasing the participation of underrepresented groups in research through established programs for recruitment and retention of underrepresented students at the University of Pittsburgh, and (iv) outreach to K-12 students through collaboration with Carnegie Science Center in Pittsburgh.
