Dialysis apparatus for

Banker, M.J., Clark, T.H. and Williams, J.A. (2003) Development and validation of a 96-well equilibrium dialysis apparatus for measuring plasma protein binding. Journal of Pharmaceutical Sciences, 92, 967-974. 

Fig. 4 Continuous dialysis apparatus for the parallel purification of up to twelve samples...

One factor in the reduction of healthcare expenditure is home medical care, which involves adaptations of the methods of care. These uses dictate particular requirements for sterility, safety, reliability, weight and facility of use. Plastics can bring solutions in the fields of single-use products, unbreakable equipment and weight reduction, for example, in the syringes, tubes and pumps for drug injections and apparatus for ambulatory dialysis. 

In our laboratories, extensive use has been made of vapor pressure (14-18) and membrane methods ( 2, 3, 19, 20) to Infer thermodynamic results for ternary aqueous systems containing an ionic or a nonionic surfactant and an organic solute. The most precise solubilization measurements ever reported have been obtained with an automated vapor pressure apparatus for volatile hydrocarbon solutes such as cyclohexane and benzene, dissolved In aqueous solutions of sodium octylsulfate and other Ionic surfactants (15, 16). A manual vapor pressure apparatus has been employed to obtain somewhat less precise results for solutes of lower volatility (17, 18). Recently, semi-equilibrium dialysis (19, 20) and MEUF (2) methods have been used to investigate solute-surfactant systems in which the organic solubilizates are too involatile to study by ordinary vapor pressure methods. 

Besides the basic apparatus for microdialysis perfusions, fraction collection, and HPLC analysis, several additional instruments and devices are needed, depending on where the microdialysis probe is to be implanted. The most complicated instrumental setup is probably that required for brain dialysis. A stereotaxtic instrument and a stereomicroscope are necessary for precise positioning of microdialysis cannulae into various brain structures. Inhalation anesthesia is preferable and more convenient than injections. However, this type of anesthesia calls for additional equipment, such as air lines, valves, and mixing chamber for halothane or other anesthetic gases, as well as good ventilation of the operation theater. 

Apparatus for studying the many variables in suppository formulation has been designed to measure rates of release in vitro. Both a circulating dissolution apparams and a dialysis device utilising an aqueous and a nonaqueous phase have been described, and are discussed in section 12.3.1. 

A significant leap forward was made in 1988 by Spirin et al. [4], who developed a continuous-flow apparatus for the continuous supplementation of reaction mixtures with substrates required for protein synthesis and continuous removal of reaction by-products. In this way, it was shown that the activity of a cell-free system could be sustained for many hours, compared with batch-mode reactions which became inactive after approximately 45 minutes. Since then, many reports have been made describing the use of simple dialysis systems [3, 5] that can maintain the high productivity of a reaction over many hours, without the use of a cumbersome apparatus. 

Figure 36-5. Apparatus for hollow fiber filter dialysis.

FIGURE 20.5 Illustration of USP apparatus 4 equipped with dialysis adapter for in vitro release testing of dispersed systems. 

Apparatus for Dialysis. Beside Graham s dialyzer, already described on page 7, Several others are in use. Generally a membrane is stretched across an open vessel and the whole partially submerged in a larger vessel filled with distilled water as in Fig. 4. If continuous... 

Fill the gel particles together with the surrounding buffer into the tube. The tube is inserted into the vertical electrophoresis apparatus (dialysis membrane down to anode), electrode buffer is poured, and electroelution is started with 10 mA per tube for 3-8 h, depending on tbe molar mass of the protein. 

In bioprocesses, a variety of apparatus that incorporate artificial (usually polymeric) membranes are often used for both separations and bioreactions. In this chapter, we shall briefly review the general principles of several membrane processes, namely, dialysis, ultrafiltration (UF), microfiltration (MF), and reverse osmosis (RO). 

The apparatus is modified from that of Klerx et al. (1) and is represented diagrammatically in Fig. 1. High cell densities can be maintained by constant perfusion of medium through the hollow fibers of dialysis membrane (molecular weight cutoff usually 10,000) with minimal dilution of the MAb. The assembled apparatus, which can be moved readily around the laboratory on a small trolley, is designed for use m a controlled 37°C warm room, but can also be set up in an incubator that has the appropriate access ports. The equipment is inexpensive, and is simple to assemble and operate. 

An alternative to the tank transfer system is the semidry transfer system. In this procedure, the gel is stacked horizontally on top of the membrane in the transfer apparatus. Because only a small volume of transfer buffer is used, SDS from the gel is less effectively diluted, which may result in incomplete binding and lower yields, especially with PVDF membranes. For this reason, semidry transfer units are not recommended when reproducible high recoveries of electroblotted proteins are desired (e.g., for subsequent sequence analysis). Some procedures recommend stacking multiple transfer sandwiches to achieve several transfers simultaneously. To prevent unbound protein from migrating through the next gel and onto the membrane in the next transfer stack, sheets of porous cellophane sheets or dialysis membrane are placed between adjacent transfer stacks (see Fig. B3.2.3). Semidry electrotransfer requires shorter transfer times than tank transfer. 

An alternative method for reducing excess salts was described by Chen etal. (20), wherein the sample was placed in a dialysis tube then dialyzed against a degassed, dilute salt solution. This method and apparatus are effective when large amounts of reduced sample are required ... 

Preconditioning of Membrane prior to dialysis, the membranes are pre-conditioned by soaking in water for 15 min, followed by soaking in PBS for 30 min. The cells are filled at ambient temperature, and when fully loaded the Dianorm apparatus is placed in a water bath at 37 °C and started at 12 rpm. 

Fig. 4. Scatchard plots for the binding of tilorone hydrochloride to calf thymus DNA (a) Me. lysodeikticus DNA (b) poly (dA-dT) poly (dA-dT) (c) and poly (dG-dC) poly (dG-dC) (d). Each different symbol corresponds to a separate experiment. Thus, each figure represents a set of 4 or 5 separate experiments, r is moles of bound tilorone/base pair concentration and (u) is the concentration of unbound tilorone. Equilibrium dialysis was carried out by a procedure and an apparatus (Dianorm, supplied by Dr. Virus KG, Bonn, Germany) described by Weder et al.61 Dialysing membrane (0.02S mm thick) was sandwiched between two halves of a Teflon (round) macro-cell (dialysable volume = 1 ml). The DNA, or labelled tilorone solutions were introduced by separate micro syringes on either side of the membrane through the side valves. The valves were closed air tight and the macro-cells were fixed into a rotating machine. All equilibrium dialysis studies were carried out at 20°, and at 10 rotations/min. Under these conditions equilibrium was attained in 4-5 hr. After the equilibrium was reached 0.8 ml of the solution from either side of the membrane was withdrawn by microsyringes and the radioactivity was determined using dioxan scintillation fluid...

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