Abstract: A chemical analyzer in which the measurement of the change in attenuation of RF radiation propagated through a sample is used as the basis for calculating the change in concentration of a given chemical in the sample. Also disclosed are various probe and system designs which facilitate the use of RF attenuation as a basis for measurement of certain chemical characteristics of a sample.

Abstract: Efficient mixing is promoted in a turbulent stirring unit by providing an agitator with flexible finger-like appendages and by varying the rate of rotation of a rotating magnetic field such that the fingers execute an undulatory motion, disrupting laminar flow and tending to collapse the liquid vortex. Motor control for controlling the fluctuation of the rotating magnetic field may provided by simple and economical electronic or electromechanical means. The control unit may be separately configured to control a number of other pieces of equipment, either in common or independently. The controller also may be integrated into stirrers, vortexers or shaker tables or externally provided to control existing units.

Abstract: Permeable capsules are loaded with a reservoir of the substance to be dispensed at a concentration sufficient to provide an osmotic pressure above threshold level, and the pore size of the capsule membrane is controlled so that the passage of the substance through the membrane becomes the rate-limiting factor in dispensing. Shape-retaining spheres are formed from a water-soluble polymer containing plural anionic or cationic groups and cross-linking surface layers of the spheres by contact with a polymer having plural groups of charge opposite that of the water-soluble polymer. After loading, the capsules are again treated with the same or a different cross-linking polymer to reduce the dimensions of the pores.

Abstract: Disclosed are dispensing systems for releasing a substance at a substantially constant rate and methods for its manufacture. The composition comprises semipermeable capsules containing the material to be released. The capsules comprise membranes having pores of dimensions sufficient to control the kinetics of release provided there is maintained a large intracapsular concentration of the substance relative to the concentration desired in the extracapsular environment. The compositions may be produced by forming permeable capsules, suspending the capsules in a solution containing a high concentration of the substance to load the intracapsular volume, and then post-treating the capsules to reduce the size of the pores.

Abstract: Disclosed is a method of growing anchorage-dependent cells: cells of the type which normally undergo mitosis only when anchored on a substrate, e.g., fibroblasts or epithelial cells. The method comprises the steps of encapsulating a seed culture of the cells within a semipermeable membrane and suspending the capsules in a growth medium. The interior surfaces of the capsule membrane and/or collagen enclosed within the capsules serve as a substrate for the cells. The ratio of the available substrate surface area to the volume of the culture may be large, thereby allowing the cells to be grown substantially throughout the volume of the culture medium.

Abstract: Disclosed is a system and process for producing substances produced in cells such as antibodies and biological response modifiers. Cells which produce the substance of interest are encapsulated within semipermeable membranes having an upper limit of permeability sufficient to allow traverse of ions, amino acids and other cell nutrients and then suspended in a culture medium. Serum components or other high molecular weight materials needed for ongoing viability and normal in vitro metabolism of certain types of cells may be included within the intracapsular volume and may be excluded from the extracapsular medium by limiting the permeability of the membranes. The substance of interest collects either in the intracapsular volume or the extracapsular medium, depending on the degree of permeability of the membranes and on the molecular weight of the substance.

Abstract: Disclosed is a process for microencapsulating a core material and subsequently releasing the core material by selectively disrupting the membranes of the microcapsules. The encapsulation technique involves the formation of a semipermeable membrane, e.g., around a droplet, through the formation of multiple ionic salt bonds between a polyionic polymer in the droplet and a crosslinking polyionic polymer which possesses multiple ionic groups of opposite charge. The membrane can be selectively disrupted by exposing it first to a solution of competing crosslinking multivalent (preferably di or trivalent) ions followed by a solution of a competing polyionic polymer of the same charge as the polymer in the original droplet. Alternatively, a mixed solution of the two competing solutions may be used together. For example, a membrane comprising anionic alginate salt bonded to cationic polymer can be selectively disrupted by exposing the membrane to a mixed solution of monatomic, multivalent cations, e.g.

Abstract: Tissue cells such as islet of Langerhans cells or liver cells are encapsulated within a spheroidal semipermeable membrane comprising a polysaccharide having acidic groups cross-linked with a polymer having a molecular weight greater than 3,000. The cells within the microcapsules are viable, healthy, physiologically active and capable of ongoing metabolism. The encapsulated cells are useful for implantation in a mammalian body to produce substances and effect chemical changes characteristic of the cells in vivo tissue.

Abstract: Disclosed is a process for encapsulating oils and oil-soluble substances in multi-compartmentalized, mechanically stable microcapsules. The process comprises the steps of first forming an emulsion consisting of a continuous phase comprising an aqueous solution of an alkali metal alginate and optionally a water-soluble, alcohol-insoluble filler such as a polysaccharide, and a dispersed phase of an oleophilic substance such as one or more vitamins dissolved in an oil. The emulsion is then formed into droplets which are thereafter immersed in an alcoholic solution of multivalent cations, to produce a shape-retaining alginate matrix filled with precipitated polysaccharide and enclosing plural oil droplets. The vitamins are thereby protected from oxidative degradation and can be handled like conventional crystalline solids.

Abstract: A core material such as living tissue, individual cells, hormones, enzymes or antibodies is encapsulated in a semipermeable membrane that is permeable to small molecules for contact with the core material but is impermeable to potentially deleterious large molecules. Encapsulation may be carried out by suspending the core material in an aqueous medium containing a water soluble gum that can be reversibly gelled, forming the suspension into droplets, contacting the droplets with a solution of multivalent cations to gel the droplets as discrete, shape-retaining, water insoluble temporary capsules and cross-linking a surface layer of the temporary capsules to produce a semipermeable membrane around the capsules. Optionally the gel within the membrane may be reliquified by removing multivalent cations from the gel.

Abstract: A two step interfacial polymerization process for encapsulating operative chemically active substances in high quality semipermeable membranes. An emulsion is formed wherein the discontinuous phase contains the substance to be encapsulated and a first monomer. When a second monomer is added to the continuous phase, an imperfect membrane forms about the droplets of the discontinuous phase. Removal of the continuous phase, followed by resuspension of the raw microcapsules and addition of a second portion of second monomer, causes further polymerization strengthening the membranes and "patching" macroporous defects in them. The choice of solvents and control of reaction conditions such as pH, maximize the yield of operable labile substance encapsulated. A method of encapsulating a very high concentration of hemoglobin is also disclosed. Adaption of the two step process provides a method for forming and controlling the pore sizes in the membranes of a number of known prior art encapsulation processes.

Abstract: A process for producing microcapsules of controlled porosity containing a chemically active core material. A core material such as a biologically active material and a first monomer in aqueous solution are emulsified in a hydrophobic solvent. A monomer complementary to the first and soluble in the continuous, hydrophobic phase of the emulsion is added to initiate interfacial polymerization about the aqueous droplets. During the course of the reaction, the affinity of the continuous phase for the first monomer is varied by adding a solvent to the continuous phase to vary its polarity. The continuous phase may be relatively nonpolar at the outset and a polar solvent may be added to increase its affinity for the first monomer, or it may be relatively polar at the outset and a nonpolar (or less polar) solvent may be added.

Abstract: Disclosed is a process for determining the concentration of unbound hormone, e.g., thyroxine, cortisol, or testosterone, in a liquid sample containing hormone and protein capable of binding the hormone. The sample is incubated with antibody specific to the hormone to be detected and a distinguishable analogue of the hormone, both of which are separated from the sample by semipermeable membranes capable of excluding the passage of natural protein and antibody but which allow passage of the hormone and its analogue. Preferably, the antibody and analogue are contained in semipermeable microcapsules. Free hormone in the sample permeates the membranes and competes for sites of attachment to the antibody with the analogue. The antibody and free hormones are then separated. The amount of analogue present either in association with the antibody or in the remainder of the reaction system is indicative of the level of free hormone originally present in the sample.

Abstract: Chemical analysis of a sample with reagents spotted on a fibrous or porous medium employs a medium pretreated both with reagents and with conditioning agent. The conditioning agent increases the degree to which the liquid reactants wet the medium. One form of pretreated medium has different reagents located predominantly within different selected zones.Liquid is applied to the medium, typically as diluted sample, at a rate selected to enhance formation of repeatable spots. In one embodiment the liquid is applied by flowing it onto a wick element seated on the medium. The wick is disc-like and small relative to the spot which the reactants form on the medium. The disc can be pretreated to carry reagent, which the liquid transfers to the medium.The analysis instrument receives a reaction medium between selectively recessed upper and lower surfaces aligned in opposition at the reaction spot being analyzed.

Abstract: Semipermeable microcapsules are employed as a medium to chromatographically separate mixtures of solutes. The microcapsules comprise membranes having a selected upper limit of permeability and contain a filler material capable of maintaining the membranes in a distended position. In use, the capsules are packed in a column and equilibrated with the solvent of the mixture to be separated. Components in the mixture are separated when passed through the column on the basis of their molecular diameter. The material is well suited for resolving components of a mixture of solutes in the 100-5000 molecular weight range.In another embodiment, a specific binding substance such as an antibody is confined within capsule membranes permeable to the antibody's complementary antigen to produce a material useful in affinity chromatography.

Abstract: A process for determining an immunogenic substance present in a sample wherein the immunogenic substance in the sample competes with a distinguishable analog of such substance for available binding sites on an antibody which is highly specific for the immunogenic substance in the sample. The antibody is encapsulated in a semi-permeable microcapsule.A specific example of the foregoing procedure is the determination of digoxin present in serum wherein the digoxin in the serum competes with radioiodine labeled digoxin for available binding sites on an antibody which is highly specific for digoxin and has been previously encapsulated in semi-permeable microcapsules. The concentration of digoxin in the sample is determined from a standard curve by relating digoxin concentration inversely to the percent of radioiodine labeled digoxin that is complexed to the antibody.

Abstract: Techniques for producing semipermeable microcapsules by interfacial polymerization are disclosed. The material to be encapsulated and a hydrophilic monomer are emulsified within a hydrophobic continuous phase. Polymerization is initiated by dissolving a second monomer in the continuous phase, and occurs only at the interface of the emulsion to result in the formation of macroporous, poorly defined capsule membranes. Next, the affinity of the continuous phase for the hydrophilic monomer is varied by altering the polarity of the continuous phase. This step is accomplished either by isolating and resuspending the raw capsules in a fresh continuous phase of different polar character, or by mixing a second solvent with the continuous phase. By controlling the affinity and the concentration of the second monomer, it is possible to produce microcapsules having uniform capsule membranes and a selected upper limit of permeability.

Abstract: An optically-thin preparation of a sample solution and chemical reagents produces a constituent-manifesting reaction product that can be measured in linear relation to the concentration of the constituent of interest. A fibrous sheet contains the sample and the reagents for both the reaction and the measurement. The same site on the fibrous sheet which bears the reacting materials serves as a blank to produce a reference signal for the measurement.

Abstract: A press for compressing a liquid-bearing absorbent article to transfer a portion of the liquid materials to a contiguous article has two concentric pressure feet. One is an outer foot member that bears against the liquid-bearing article along the periphery of the pressure area, and the other is an inner, deformable and contoured foot member that applies pressure to the liquid-bearing article progressively along the pressure area. A photometer can be combined with the press to measure constituents or other properties of the liquid materials being transferred.