Responsive hydrogels hydrogel system

Kim, S.Y. Lee, S.C. 2009, Thermo-responsive injectable hydrogel system based on poly (N-isopropylacrylamide-co-vinylphosphonic acid). I. Biomineralization and protein dehvery , Journal of Applied Polymer Science, vol. 113, pp. 3460-3469. 

Major developments have been reported in the utilization of environmentally responsive hydrogels as glucose-sensitive systems that... 

Responsive polyelectrolyte hydrogels that have been used for controlled release systems include gels which are hydrophobic in their neutral state... 

Chemically Controlled Flow Systems Based on Responsive Hydrogels ... 

In summary, the steady state and transient performance of the poly(acrylamide) hydrogel with immobilized glucose oxidase and phenol red dye (pAAm/GO/PR) demonstrates phenomena common to all polymer-based sensors and drag delivery systems. The role of the polymer in these systems is to act as a barrier to control the transport of substrates/products and this in turn controls the ultimate signal and the response time. For systems which rely upon the reaction of a substrate for example via an immobilized enzyme, the polymer controls the relative importance of the rate of substrate/analyte delivery and the rate of the reaction. In membrane systems, the thicker the polymer membrane the longer the response time due to substrate diffusion limitations as demonstrated with our pAAm/GO/PR system. However a membrane must not be so thin as to allow convective removal of the substrates before undergoing reaction, or removal of the products before detection. The steady state as well as the transient response of the pAAm/GO/ PR system was used to demonstrate these considerations with the more complicated case in which two substrates are required for the reaction. 

Fig. 12. Model scheme for an on-off switching drug release system consisting of a biochipsensor and a drug including an electrically responsive hydrogel...

Reactive or catalytic systems are based on pH-responsive hydrogels where the chosen reaction generates a pH shift, which in mm leads to a swelling change in the hydrogel. This response can either be used to increase the internal mesh size to increase solute diffusivity in the gel phase for a diffusive membrane [44] or alternatively the gel can be used as a mechanical valve within the pores of a microporous membrane such that a convective flux may be mmed on or off in response to analyte... 

De SK, Alum NR, Johnson B, Crone WC, Beebe DJ, and Moore J. Equihbrium swelling and kinetics of pH-responsive hydrogels Models, experiments, and simulations. Journal of Microelectromechanical Systems 2002 11 544—555. 

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