Abstract: Bioactive microcapsules containing Bacillus thuringiensis (BT) spores were generated by a combination of a hydro gel, microfluidic device and chemical polymerization method. As a proof-of-principle, we used BT spores displaying enhanced green fluorescent protein (EGFP) on the spore surface to spatially direct the EGFP-presenting spores within microcapsules. BT spore-encapsulated microdroplets of uniform size and shape are prepared through a flow-focusing method in a microfluidic device and converted into microcapsules through hydrogel polymerization. The size of microdroplets can be controlled by changing both the dispersion and continuous flow rate. Poly(N-isoproplyacrylamide) (PNIPAM), known as a hydrogel material, was employed as a biocompatible material for the encapsulation of BT spores and long-term storage and outstanding stability. Due to these unique properties of PNIPAM, the nutrients from Luria-Bertani complex medium diffused into the microcapsules and the microencapsulated spores germinated into vegetative cells under adequate environmental conditions. These results suggest that there is no limitation of transferring low-molecular-weight-substrates through the PNIPAM structures, and the viability of microencapsulated spores was confirmed by the culture of vegetative cells after the germinations. This microfluidic-based microencapsulation methodology provides a unique way of synthesizing bioactive microcapsules in a one-step process. This microfluidic-based strategy would be potentially suitable to produce microcapsules of various microbial spores for on-site biosensor analysis.
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Kim, B.I.; Jeong, S.W.; Lee, K.G.; Park, T.J.; Park, J.Y.; Song, J.J.; Lee, S.J.; Lee, C.-S. Synthesis of Bioactive Microcapsules Using a Microfluidic Device. Sensors 2012, 12, 10136-10147.
Kim BI, Jeong SW, Lee KG, Park TJ, Park JY, Song JJ, Lee SJ, Lee C-S. Synthesis of Bioactive Microcapsules Using a Microfluidic Device. Sensors. 2012; 12(8):10136-10147.
Kim, Byeong Il; Jeong, Soon Woo; Lee, Kyoung G.; Park, Tae Jung; Park, Jung Youn; Song, Jae Jun; Lee, Seok Jae; Lee, Chang-Soo. 2012. "Synthesis of Bioactive Microcapsules Using a Microfluidic Device." Sensors 12, no. 8: 10136-10147.