Detachment from Polymer-Grafted Surfaces

Polymer-Carrying Liposomes for Triggered Release/Dnig Delivery 

If the liposomes in question are treated with the polymer after their formation, the polymer binds only to the outer surface of the liposomes. If the liposomes are formed from a lipid-polymer mixture, on the other hand, the polymer is present on both sides of the liposome membrane. Such liposomes respond even faster to temperature changes. The change of the liposome surface properties caused by the phase transition of stimulus-responsive polymers in also known to affect their interaction with cells. The phenomenon has been used in an attempt to develop a targeted drug delivery system. Liposomes modified with a pH-sensitive polymer, namely succinylated poly(glycidol), were shown to deliver the dye cacein more efficiently into cultured monkey kidney cells than nonmodified liposomes.  

Harland RS, Prud homme RK, eds. Polyelectrolyte Gels. Properties, Preparation, and Applications. 

Dusek K, ed. Responsive Gels Volume Transitions II. Berlin Springer-Verlag, 1993 180-197. 

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Yamato, M., Okuhara, M., Karikusa, F., Kikuchi, A., Sakurai, Y, Okano, T. (1999). Signal transduction and cytoskeletal reorganization are required for cell detachment from cell culture surfaces grafted with a temperature-responsive polymer. Journal of Biomedical Materials Research, 44, 44—52. 

From these reports as described previously, PIPAAm polymer brush surfaces with a density of around 0.04 PIPAAm chains/mn and relatively thinner PIPAAm layer seem to be optimal for expressing a temperature-induced cell attachment and detachment character. The optimizations of graft polymer density and graft polymer chain length are expected to be useful to produce TRCS for culturing various cell species. 

Surface prop>erties can be modified by thin layers of grafted polymers on a surface (not only flat substrates, but also colloidal particles, fibers, etc). These layers can be fabricated by grafring-from (as radical polymerization at the interface) and grafring-to (as tethering of the polymer chains from solution) methods. Grafted surfaces using smart temperature-responsive polymers can modulate cell adhesion and detachment properties in dependence on the temprerature. Cells adhere and proliferate on hydrophobic surfaces rather than hydrophilic ones. They tend to adhere to the surface with appropriate hydrophobidty. Polymer brush systems can be used to control adsorption mechanism, for example, protein adsorption or adsorption of nanopartides. 

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