Dextran,Hydrogels

Dextran hydrogels, cross-linked by diisocyanate, released drug only in the distal part of the colon, where the conditions for absorption are not as conducive as in the proximal part [96], The pH-sensitive dextran hydrogels were prepared by activation... 

Simonsen, L., Hovgaard, L., Mortensen, P.B., and Brondsted, H., Dextran hydrogels for colon-specific drug delivery. Degradation in human intestinal incubation models, Eur. J. Pharm. Sci., 3 329-337 (1995). 

Chiu, H.C., Hsiue, G.H., Lee, Y.P., and Huang, L.W., Synthesis and characterization of pH-sensitive dextran hydrogels as a potential colon-specific drug delivery system, J. Biomater. Sci. Polym. ed., 10 591-608 (1999). 

Y. Zhou, O. Andersson, P. Lindberg and Liedberg, B. (2004) Protein microarrays on carboxymethylated dextran hydrogels immobilization, characterization and application. Microchim. Acta., 147, 21-30. 

Franssen, 0., Vandervennet, L., Roders, P, and Hennink, W. E. Degradable dextran hydrogels Controlled release of a model protein from cylinders and microspheres. J. Contr. Rel. 60 211-221, 1999. 

L. Hovgaard, and H. Brpndsted, Dextran hydrogels for colon-specific drug delivery, J. Controlled Release 36 159-166 (1995). 

Casadei, M. A., et al. (2006), Solid lipid nanoparticles incorporated in dextran hydrogels A new drug dehvery system for oral formulations, Int. J. Pharm, 325(1-2), 140-146. 

Dextran hydrogels have been successfully applied in biosensors based on surface plasmon resonance. Carboxymethyl-dextran (CM-dextran) hydrogel was the original sensor surface developed for biomolecular interaction analysis and hence the most extensively studied and versatile. It has been used in a very wide range of interaction analyses including those between proteins, nucleic acids, and carbohydrates [40,41]. 

Hennink WE, Eranssen O, van Dijk-Wolthuis WNE, and Talsma H. Dextran hydrogels for the controlled release of proteins. Journal of Controlled Release 1997 48 107-114. 

Chiu HC, Wu AT, and Lin YE. Synthesis and characterization of acrylic acid-containing dextran hydrogels. Polymer 2001 42 1471-1479. 

Hennink WE, Talsma H, Borchet JCH, de Smedt SC, and Demeester J. Controlled release of proteins from dextran hydrogels. Journal of... 

Zhang R. Dextran Hydrogel Preparation and Application in Biomedical Engineering. PhD Thesis, University of Bath, England, 2004. 

Temporary replacement skins have also been studied by using velour fabrics (usually a nylon or Dacron) backed by a polymeric film (silicone or protein) (36). synthetic polypeptides (37). collagen (38). and dextran hydrogels (39). These replacement materials are only for short term use and could be classed as wound dressings. Although they do prevent gross infection and body fluid loss, they do not duplicate any of the other functions of the skin. A true artificial skin does not yet exist. 

Tsuda Y, Kikuchi A, Yamato M et al (2005) The use of patterned dual thermoresponslve surfaces for the collective recovery as co-cultured cell sheets. Biomaterials 26 1885-1893 Tsuda Y, Shimizu T, Yamato M et al (2007) Cellular control of tissue architectures using a three-dimensional tissue fabrication technique. Biomaterials 28 4939 946 Van Tomme SR, Hennink WE (2007) Biodegradable dextran hydrogels for protein delivery applications. Expert Rev Med Devic 4 147-164... 

The internal organs were also sterile. Therefore to be effective, the AgN03 dextran hydrogel paste should be applied to the wound surface soon after injury. 

Table I shows that a 3x3.5 cm dorsal skin wound on a Wistar rat can ooze out 2.2 ml of serous fluid in about 3 days. This fluid volume is reduced to 1.2 ml, if the wound is exposed for 3 hr before treatment. Beyond the 3 hr exposure, there may be further reduction in oozing, but the chance of eschar formation will also increase. Various compositions of the AgN03 medicated dextran hydrogel paste have been evaluated. The one with a good spreadability and fluid absorption has been used in the present study. Measurements by a simple hygrometric method showed that the medicated paste on the wound reduced evaporative loss by almost 50% as compared to an open wound which had a rate of 93 mg H20/cm /hr (7.). On subsequent days, the relatively steady value of 12.5 mg H20/cm /hr was about 2x higher than the evaporative loss of the paste spread over a plastic sheet used as a control. The higher evaporative rate of the paste on the wound site might be due to the transmission of excess moisture from the wound surface. The oozing serous fluid had apparently been first absorbed into the paste, because no exudate accumulation was ever observed under the paste coating. The humectant in the paste which retained moisture obviously must have kept the wound surface sufficiently moist to prevent eschar formation.

Franssen O, Vos OP, Hennink WE. Delayed release of a model protein from enzymatically degrading dextran hydrogels. J Control Release 1997 44 237-245. 

De Jong SJ, Van Eerdenbrugh B, Van Nostrum CF, Kettenes-van den Bosch JJ, Hennink WE. Physically crosslinked dextran hydrogels by stereocomplex formation of lactic acid oligomers degradation and protein release behavior. J Control Release 2001 71 261-275. 

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