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Published on: June 17, 2014
Cellular Flocculation Driven by Concentrated Polymer Brush-Modified Cellulose Nanofibers with Different Surface
Chiaki Yoshikawa1, Keita Sakakibara2, Punnida Nonsuwan1
1Research Center for Functional Materials, National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0047, Japan.
Abstract:
This study examined the effect of the surface charge of concentrated polymer brush (CPB)-grafted cellulose nanofibers (CNFs) on HepG2 cell flocculation. Four polyelectrolytes, poly(p-styrenesulfonic acid sodium salt) (PSSNa), poly(acrylic acid) (PAA), poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA), and poly([(2-methacryloyloxy)ethyl]trimethylammonium chloride) (PMTAC), were grafted onto the CNF surface via surface-initiated atom transfer radical polymerization to form CNF-CPBs. The floc size of HepG2 cells depended on the surface charge of CNF-CPBs, where the anionic CNF-PSSNa formed larger flocs than CNF-PAA; due to the electrostatic repulsive forces, CNF-CPBs with a lower ζ-potential yielded smaller floc sizes. Contrastingly, the cytotoxic cationic CNF-PDMAEMA and CNF-PMTAC limited the floc size growth. Thus, appropriate electrostatic interactions are essential for floc formation and improved cell function in three-dimensional (3D) cell culture systems. Interestingly, while developing a novel 3D cell culture system, we reveal that colloidal flocculation theory is the driving mechanism behind this unique phenomenon.
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