Hydrogels, chemically responsive materials

Responsive hydrogels are valuable materials for sensors, especially for sensor application in liquids, for example, online control of composition of a liquid, measurement of pH, and concentration of ions. The sensitivity of the gel depends on its chemical stmcture and can be modified in a wide range. 

Stimuli-responsive hydrogels are capable of reversibly converting chemical energy into mechanical energy. That makes them very useful as sensitive material for chemical and biosensors. The following principles for the detection of environmental parameters are used in sensors based on the swelling behavior of hydrogels ... 

Guiseppi-Elie A, Brahim S I, Narinesingh D (2002) A chemically synthesized artificial pancreas release of insulin from glucose-responsive hydrogels. Adv. Materials 14(10) 743-746 Heller A (1996) Amperometric biosensors. Curr Opin Biotechnol 7(l) 50-54 Heller A (2006) Electron-conducting redox hydrogels design, characteristics and synthesis. Curr Opin Chem Biol 10(6) 664—672... 

The nonadsorptive nature of these materials allows for their modification in order to include specified biological signals. Cells will not adhere to hydrogels without chemical or biological modification of the material. While it may seem that lack of cell adhesion to materials intended for tissue engineering applications would not be a desirable property, this is not necessarily the case. This anti-adhesive property is beneficial, as it allows precise, defined modifications of the material to achieve a specific cellular response without interference by nonspecific cell or protein interactions. 

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