Event Abstract Back to Event Fabrication and magnetic control of alginate-based cellular micro robots Jamel Ali1, Yigong Liu1, Hoyeon Kim1, U Kei Cheang1, Wei Sun1 and Min Jun Kim1 1 Drexel University, Department of Mechanical Engineering & Mechanics, United States Introduction: Since calcium alginate hydrogels were first used to encapsulate cells in the late 1970s, alginates have garnered significant research attention for biological and medical applications. One such application, cell positioning, using alginate particles presents huge potential in emerging fields of 3D cell patterning, single cell analysis, and cell therapy. Here we describe the microfluidic fabrication and wireless control of alginate microparticles encapsulating both magnetic particles and viable mammalian cells. Using a rotational magnetic felid we demonstrate the ability to guide cell-laden particles to target locations. Materials: Sodium alginate, calcium chloride, and sodium chloride were obtained from Sigma Aldrich and were used without further purification. Sodium alginate solutions were prepared at 5% (w/w) in 150 mM NaCl. Calcium chloride solutions were prepared at 2.5% (w/w). All solutions were prepared using water deionized to 18 MΩ cm (Millipore MilliQ). Methods: Cell Culture: Human breast cancer cells, MDA-MB-231, were obtained from the American Type Culture Collection and cultured in DMEM (without calcium chloride and magnesium chloride) supplemented with 10% fetal bovine serum, 100 U/ml penicillin/streptomycinin, in a humidified incubator at 37oC with 5% CO2. Fabrication of magnetic cell loaded alginate microparticles: Cell encapsulated microparticles were fabricated using a centrifuge-based method[1]. Briefly, to a 5% sodium alginate solution, iron oxide nanoparticles (5% (w/w)) were added thoroughly mixed, and subsequently autoclaved. Then breast cancer cells, washed in fresh DMEM media, were gently resuspended in the autoclaved sodium alginate solution. The final alginate solution, containing cells and magnetic microparticles, was then loaded into a 32G needle that was fixed in a 1.5 mL microtube containing 1.2 mL of 2.5% (w/w) CaCl2. Finally, magnetic cell loaded particles were formed as droplets were ejected from the needle into the CaCl2 solution during centrifugation at 2000G for one minute. Results: Alginate microparticles, 100-200 µm in diameter, that encapsulated magnetic particles and breast cancer cells were successful fabricated (Fig.1a). Once fabricated, microparticles were magnetically actuated using an external magnetic felid generated using a previously reported approximate Helmholtz configuration[2]. Using feedback control, a 100 μm alginate microparticle was manipulated to move in a DU pattern (Fig.1b). Figure 1. (a) Fluorescence microscopy of breast cancer cells, in green, encapsulated in an alginate microparticle, in blue (b) Trajectory of an alginate microparticle magnetically controlled to move in a ‘DU’ pattern. Discussion: Fabricated microparticles resting at the bottom of a closed chamber were rotated up to 0.2Hz using an 8.32mT rotating magnetic field. Due to the external field particles rolled across the glass substrate in such a way that their movement was oriented with the applied magnetic field. Conclusions: We have successfully demonstrated the fabrication of cell-laden microparticles and show the ability to navigate these particles by manipulating an external magnetic felid. From these results we believe that by using magnetic actuation alginate microgels have the potential to be used for future wireless microrobotic applications such as single cell analysis and cell therapy. This work was funded by National Science Foundation (CMMI 1000255), Korea Evaluation Institute of Industrial Technology (KEIT) funded by the Ministry of Trade, Industry, and Energy (MOTIE) (NO. 10052980) awards to Min Jun Kim, and by a National Defence Science and Engineering Graduate Fellowship (NDSEG) awarded to Jamel Ali.
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Nov 10, 2023
Ye Dai + 5
Open Access