Hydrogel membrane

BD Ratner, IF Miller. Transport through crosslinked poly(2-hydroxyethyl methacrylate) hydrogel membranes. J Biomed Mater Res 7 353-367, 1973. 

A Domb, GW Davidson HI, LM Sanders. Diffusion of peptides through hydrogel membranes. J Controlled Release 14 133-139, 1990. 

The significance of the permeability depends upon the particular system at hand. If the hydrogel forms a barrier between a drug reservoir and a solution, the flux across the hydrogel membrane at steady state is simply... 

Permeability control of solutes through thermosensitive hydrogel membranes may be thought of in terms of the degree of hydration and kinetics of... 

SW Kim, JR Cardinal, S Wisniewski, GM Zenter. Solute permeation through hydrogel membranes, hydrophilic vs. hydrophobic solutes. ACS Symp Ser 127 347-359, 1980. 

GM Zentner, JR Cardinal, SW Kim. Progestin permeation through polymer membranes, II Diffusion studies on hydrogel membranes. J Pharm Sci 67(10) 1352-1355, 1978. 

Ishihara, K., Ueda, T. and Nakabayashi, N. (1990) Preparation of phospholipid polymers and their properties as polymer hydrogel membranes. Polymer Journal, 22, 355-360. 

Figure 10. Hydrogel membrane (a) and their application as wound dressing (b).

Figure 11. Scheme of a bioartificial pancreas surrounded by a hydrogel membrane [266], Some methods used for artificial organs design are presented in table 17. 

Hydrogel membranes are particularly attractive because of high permeability and separation factor [300], and good stability for CO2/N2 separation [299], PVDF hollow fiber membrane modified by alkali was coated by PYA hydrogel on its surface and PVDF-PVA hydrogel membranes show better hydrophilic performance. For carbonate hydrogel (sodium carbonate concentration of 3.7 %) membrane, C02, concentration from 1.3 % to 0.6 % in feed gas could be decreased to 0.9-0.4 % at the outlet at 25 °C. 

Hydrogel membranes fulfill many of the important conditions for most of above-mentioned application fields. Therefore, we have focused our paper on the applications of PVA-based membranes in areas such as for separation membranar processes, fuel cells, sensors, biochemical/medical applications, catalyst or PVA derivatives membranes as gas and vapor barriers. 

J. P. Baker and R. A. Siegel, Poly(A-isopropylacrylamide) hydrogel membranes for pulsatile drug delivery, Proc. Int. Symp. Control Release Bioact. Mater, 22, 340-341 (1995). 

Several theories have been proposed to calculate the molecular weight between crosslinks in a hydrogel membrane. Probably the most widely used of these theories is that of Flory and Rehner [5]. This theory deals with neutral polymer networks and assumes a Gaussian distribution of polymer chains and tetrafunctional crosslinking within the polymer network. 

In another model, Harland and Peppas [159] considered the diffusion of solutes through semicrystalline hydrogel membranes. These types of membranes were assumed to consist of a crosslinked, swollen (amorphous) phase through which solute diffusion occurred and an impermeable, crystalline phase. A simplified form of the model assumes uniform amorphous regions. With this assumption, the diffusion coefficient through a semi-crystalline membrane, Dc, was written as... 

The device will have to hold within its volume a colony of hepatic cells and perhaps a hydrogel membrane and still have enough void volume to allow physiologically correct blood flow. Hepatic diameters spheroids are about 100 pm." In order for a scaffold to contain a significant number of hepatic cells and still be able to handle the flow rates required, it must have a large void volume. 

Hirai T., Asada Y., Suzuki T., et al., Studies on elastic hydrogel membrane. I. Effect of preparation conditions on the membrane performance 3. Appl. PolymerS., 38 (1989) 491. 

An important parameter in a number of fields is the study of inorganic phosphate. Recently, Kwan et al. [206,207] have reported on a screen-printed phosphate biosensor based on immobilised pyruvate oxidase (PyOD) for monitoring phosphate concentrations in a sequencing batch reactor system [206] and in human saliva [207]. The enzyme was immobilised by drop-coating a Nation solution onto the working electrode surface this was then covered by a poly(carbamoyl) sulfonate (PCS) hydrogel membrane. 

The thin hydrogel membranes exhibit a fast response time of 25 sec to 98% equilibrated signal and a fast hydration time of several minutes. The sensor chips can be stored dry for at least one year at 4 °C without changes in performance. 

The same transducers covered with the polyHEMA membranes can serve as a basis for several other amperometric sensors. The optimum trade-off between rapid response (thin membrane) and stirring independency (thicker membranes) should be found for each particular application (77). In many cases, the hydrogel membrane... 

Polymerization was allowed to proceed for at least 24 hours after which time the assembly was soaked in buffer at room temperature and the hydrogel membrane carefully removed. The membrane was allowed to swell in buffer for several days, with multiple changes of buffer, before its use in an experiment. 

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