Hydrogels sensitivities

Lee S. J., Park K. Synthesis and characterization of sol-gel phase-reversible hydrogels sensitive to glucose. Polym. Preprints 1994 35(2) 391-392. 

Hydrogel Sensitivity, per pH unit Signal resolution Response time, s Thickness of gel layer, pm pH range References... 

Hydrogels sensitive to environmental changes (pH, temperature, metabolite concentration) responding with swelling and eventually release of their payload drug (Guiseppi-Elie et al. 2002)... 

Hydrogels sensitive to electric fields have been demonstrated in ttie literature (Kurauchi et al. 1991 Tanaka et al. 1982 Fihpcsei et al. 2000). However, die fields have to be quite strong, sueh that an operation as a sensor is not feasible. 

Magnetic particles have been ineorporated into hydrogels to build hydrogels sensitive toward magnetic fields (Zrinyi and Szabo 2001). However, only a ehange of shape, but no volume change, can be effected. Again the effect is weak, so the gel can only be used as an actuator, not as a sensor. 

A hydrogel with high sensitivity was prepared with chitosan (DA = 0.18) and dextran sulfate the maximum volume of the complex gel was observed in a dilute NaOH solution at pH 10.5, and was about 300 times as large as the volume at pH values below 9 [106,107]. 

Lutolf MP, Lauer-Fields JL, Schmoekel HG et al (2003) Synthetic matrix metalloproteinase-sensitive hydrogels for the conduction of tissue regeneration Engineering cell-invasion characteristics. Proc Natl Acad Sci 100 5413-5418... 

SH Gehrke, EL Cussler. Mass transfer in pH-sensitive hydrogels. Chem Eng Sci 44 559-566, 1989. 

DC Harsh, SH Gehrke. Controlling the swelling characteristics of temperature-sensitive cellulose ether hydrogels. J Controlled Release 17 175-186, 1991. 

X Huang, H Unno, T Akehata, O Hirasa. Analysis of kinetic behavior of temperature-sensitive water-absorbing hydrogel. J Chem Eng Jpn 20 123-128, 1987. 

Table 2 Factors Influencing Swelling of pH-Sensitive Hydrogels... 

In the gastrointestinal tract, a mucoadhesive drug delivery system provides advantages in prolonging the residence time of devices. The use of pH-sensitive bioadhesive polymers has been proposed [26], An extensive review of pH-sensi-tive hydrogels is given by Brpndsted and Kopecek [27],... 

Ishihara [28] synthesized two hydrogel copolymers containing aromatic light-sensitive groups. They were poly(HEMA-co-p-phenylazoacrylanilide (PAAn)). Their structures are shown in Figure 5. 

L-C Dong, AS Hoffman. A novel approach for preparation of pH-sensitive hydrogels for enteric drug delivery. J Controlled Release 15 141-152, 1991. 

H Brpndsted, J Kopecek. pH sensitive hydrogels Characteristics and potential in drug delivery. ACS Symp Ser 480 285-304, 1992. 

YH Bae, IC Kwon, CM Pai, SW Kim. Controlled release of macromolecules from electrical and chemical stimuli-sensitive hydrogels. Makromol Chem, Macromol Symp 70 173-177, 1993. 

Cohen JA, Beaudette TT, Tseng WW et al (2009) T-cell activation by antigen-loaded pH-sensitive hydrogel particles in vivo the effect of particle size. Bioconjug Chem 20 111-119... 

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