Abstract: The present invention relates to the field of degradation or corrosion prevention or inhibition through the use of bacteria which secrete antimicrobial chemical compositions. In particular, the invention relates to the use of bacteria which, either naturally or through the use of recombinant technology, secrete chemical compositions which inhibit the growth of sulfate-reducing bacteria on metals, concrete, mortar, and other surfaces subject to corrosion.

Abstract: A process to render flame- and fireproof surfaces and materials and inhibit the spread of fire on materials of various, and diverse, chemical nature and affinity, using one basic fire and flame retardant material, with wide ranging chemical affinity. Preparations are non toxic, for professional and household use, in a stable colloidal dispersion. Intumescent mixtures include a base comprising a source of phosphoric acid, a charring agent and a blowing agent, further comprising flame spread reduction materials, thermal resistance enhancers, thermal transmission reduction and refractory, elasticity, water resistant materials, and combinations thereof. Preparations are further treated with activated bipolar chemicals to change their chemical affinity, to make them applicable to synthetic and metallic substrates and surfaces as well. to be used on buidling materials, furniture, home furnishings, rubber, electric wires, walls, toys, etc.

Abstract: Magnetic recording media exhibiting high SNR and high thermal stability are produced by sputter depositing a magnetic alloy overlying a non-magnetic substrate, e.g., on an underlayer, heating to eliminate thermally unstable small grains thereby increasing the average grain size of the magnetic alloy layer but narrowing the grain size distribution, depositing a layer comprising a non-ferromagnetic element, and then heating to diffuse the non-ferromagnetic element into the grain boundaries of the heat treated magnetic alloy layer. Embodiments include sputter depositing a magnetic alloy layer comprising Co and Pt on an underlayer, heating at a temperature of about 150° C. to about 600° C. to increase the average grain size to about 8 to about 10 nm, depositing a layer comprising Cr, Mn or Ta, at a thickness up to about 25 Å, e.g., up to about 10 Å, on the magnetic alloy layer and heating to diffuse the Cr, Mn or Ta into the grain boundaries of the magnetic alloy layer.

Abstract: A method of stabilizing particles with an insulating, semiconducting and/or metallic coating and stabilized particles prepared thereby are disclosed. In addition, particles stabilized by an insulating, semiconducting and/or metallic coating, wherein said coating is attached to said particles via a bifunctional ligand are provided, as is a method is provided for determining the presence of an analyte in a sample comprising incubating the sample with a ligand bound to a coated particle, capable of specifically binding to the analyte and capable of providing a detectable signal and detecting the presence of a ligand-coated particle:analyte complex as indicating the presence of the analyte in the sample.

Abstract: A system for producing multiple diagnostic test elements has a support (1) with an analytical region (3) to which diagnostic test spots (8) are applied, one or several stop edges (11-13) for each direction in space for positioning the support, a first holding unit (10I) into which the support is inserted and positioned by means of the one or more stop edges, a first printing head (20I) arranged above the holding unit (10) for applying drops of a first liquid to the analytical region of the support (1), a first positioning unit which laterally displaces and positions the first holding unit, a second holding unit (10II) into which the support is inserted and positioned by means of the one or more stop edges, a second printing head (20II) arranged above the second holding unit for applying drops of a second liquid to the analytical region of the support (1), a second positioning unit which laterally displaces and positions the second holding unit, a transport unit (41) and a control unit.

Abstract: The invention pertains to a method for the manufacture of a packaging material (1; 21) for the production of packaging blanks and packages and comprising the steps of providing at least on surface layer (2, 2′; 22, 22′) in the form of a continuous material web and substantially consisting of cellulosic fibres and applying a distance layer (3; 23) comprising a matrix material and reinforcement fibres thereto so that said surface layer (2, 2′; 22, 22′) is bonded to said distance layer (3; 23). The matrix material in the distance layer (3; 23) is in an expandable state when it is applied to the surface layer (2, 2′; 22, 22′) and is expanded in a separate process step, subsequent to the application step. The invention also concerns expandable packaging materials.

Abstract: An imaging support comprising: a polyester support; an adhesive layer superposed to said support; and on the adhesive layer: an amine modified gelatin subbing layer, the amine modified gelatin having the formula: wherein Gel is a gelatin polypeptide, is a carbonyl group from a free carboxyl group in aspartic acid or a glutamic acid moiety in said polypeptide, and G is wherein each R is independently hydrogen or a primary or secondary alkyl group of one to about four carbon atoms, n is a positive integer having a value of one to about four, and T is a hydrogen or said modified gelatin being further characterized by having from 1% to about 40% of the free carboxyl groups in aspartic and glutamic acid moieties in said polypeptide being substituted with G-groups; wherein said support has been annealed at a temperature that is 50 to 5° C. less than the glass transition temperature of the support for at least 6 hours.

Abstract: A semiconductor nanoparticle for use in analysis of biological samples is described. This semiconductor nanoparticle is composed of an aminodextran which is bound to at least one nanoparticle of the formula (X Y)n wherein X is selected from the group comprising Cd2+, Hg2+, and Zn2+ and combinations thereof, and Y is selected from the group comprising S2−, Se2− and Te2− and combinations thereof; and n=approximately 50 to 1000. Also provided are methods of making these semiconductor nanoparticles and methods of making conjugates composed of these semiconductor nanoparticles linked to ligands. Also described are uses for the conjugates in a variety of biological assays.

Abstract: In a simultaneous coating of multiple layers on a web using a slide hopper type coating apparatus, the gelatin concentration of the coating liquid for the bottom layer is set to be lower than the gelatin concentration of the coating liquid for the middle layer by at least 2 points in percentage, the ratio A/B, which is the flow amount ratio of the coating liquid for the bottom layer with respect to the entire multi-layered coating liquid, is set to be between 0.05 and 0.2, and the ratio C/D, which is the viscosity ratio between the coating liquid for the bottom layer and the coating liquid of the middle layer, is set to be between 0.2 and 0.67. Thereby, the flow of the multi-layered coating liquid flowing down on the slide surface can be stabilized.

Abstract: The inkjet recording sheet substrate of the present invention comprises a cellulosic sheet support, e.g., paper, having on at least one surface thereof a base coating comprising pigment and binder. The preferred pigment component is a 50/50 mixture of kaolin clay and calcined clay, and the preferred binder component is polyvinyl acetate. This combination of binder and pigment has been found to possess a high absorption capacity for the vehicle of an inkjet ink and good compatibility with ink receptive top coatings applied over the base coat.

Abstract: It has been found that casein and salts of casein are useful as replacements for, or in addition to, BSA as materials for coating solid phases, particularly magnetic particles, used in immunoassays and other binding assays for separation of the desired analyte. By using casein, immunoassays having improved stability and fewer discordant samples have been developed. Casein used at a concentration of 0.05-4.0 grams per gram of paramagnetic particle (optimally approximately 0.78-1.2 grams of casein per gram of magnetic particle) has been found to confer this benefit.

Abstract: Functionalized polymer surfaces having reactive moieties thereon are contacted with stamps having ligands adsorbed thereto, the ligands also comprising reactive moieties. The reactive moieties of the functionalized surfaces and the ligands form covalent bonds, thus providing a method of microstamping polymer surfaces directly with ligands such as biological ligands. Using this method, devices such as tissue culture plates with polymer surfaces that are microstamped directly with ligands can be made.

Abstract: A wettable article consisting of an article with a hydrophobic surface having a coating which includes a surface free energy modifier and a surface-active agent. The hydrophobic surface may include a hydrophobic polymer. The surface free energy modifier has a surface free energy greater than that of the surface of the article, but less than the surface tension of an aqueous liquid to which the wettable coated article may be exposed. The surface free energy modifier desirably is present in an amount sufficient to substantially cover the surface of the article. The surface-active agent is present in an amount effective to lower the surface tension of the liquid to a value which is greater than the surface free energy of the surface of the article and equal to or less than the surface free energy of the surface free energy modifier. The article desirably is a film or a fibrous web, such as a nonwoven web. Methods of preparing the wettable article also are described.

Abstract: A simple chemical approach for the covalent assembly of organic molecules on silicon surfaces via robust linkages is provided. This is achieved by the efficient reaction between a nucleophilic functional group and a halogenated Si surface. The nucleophile anchor is the bridge between two surface Si atoms. The resulting organic layer is thermally stable. The method demonstrated herein is generally applicable for the assembly of a variety of functional organic molecules under vacuum environment or in solution phase.

Abstract: A method for making a porous ink jet recording element having a uniform, protective layer by coating on a support the following layers in order: a) a porous, image-receiving layer containing a diffusible coagulant; and b) a layer containing a dispersion of particles which are capable of forming a particle gel with a coagulant; c) the diffusible coagulant thereby diffusing into the layer containing the dispersion of particles, causing the layer to set to a particle gel; and d) drying the element to obtain a uniform, protective layer on top of the porous, image-receiving layer.

Abstract: The present invention relates to a collagen material comprising a laminate in which a collagen ultra-fine fibrous non-woven fabric-like multi-layer structure is sandwiched between non-fibrous collagen layers, a thread-like material containing said collagen material, their production processes, and a medical material containing said collagen material, and particularly a medical alternative membrane comprised of said medical material.

Abstract: A semiconductor nanoparticle for use in analysis of biological samples is described. This semiconductor nanoparticle is composed of an aminodextran which is bound to at least one nanoparticle of the formula (X Y)n wherein X is selected from the group comprising Cd2+, Hg2+, and Zn2+ and combinations thereof; and Y is selected from the group comprising S2−, Se2− and Te2− and combinations thereof; and n=approximately 50 to 1000. Also provided are methods of making these semiconductor nanoparticles and methods of making conjugates composed of these semiconductor nanoparticles linked to ligands. Also described are uses for the conjugates in a variety of biological assays.

Abstract: The present invention features coating compositions and methods for improving the quality of images printed on a paper substrate. The novel coating compositions contain a coating agent comprising a mixture of a polyacid and a polybase. When applied to a sized paper substrate, the coating compositions provide a coated paper substrate that provides high quality printed images when printed with an ink containing a reactive dye having ionizable and/or nucleophilic groups capable of reacting with the coating agent. Images printed on a paper substrate coated with the coating composition of the invention are bleed-resistant, water-resistant (e.g., water-fast), and/or are characterized by an enhanced chroma and hue.

Abstract: The invention relates to the production of thin metal layers and structures thereof on substrates of various structures. The lateral extent of a metal layer on the respective substrate can be prescribed with a precision in the micron and submicron range. The method described makes it possible to manufacture flat and three-dimensional metal structures on smooth planar or curved surfaces, as are required, for example, for depicting writing or drawings. The method uses no printing techniques.

Abstract: A process involving the application of an aromatic oil-modified polyurethane coating with a softening agent to specifically prepared solid synthetic organic and natural organic formed substrate materials wherein the coating has the capability of receiving subsequently-applied coloring agents and adhesives.

Abstract: The invention relates to an improved method for the manufacture of magnetically responsive particles, also called ferrofluids. The improved method involves a heat treatment step, which may occur at various times during the preparation of the materials, including during subdivision of the magnetic starting material, during the addion of a coating material, after formation of a magnetically responsive particle, or some combination thereof. The materials formed by such a process have numerous advantages over materials formed by other processes, including enhanced salt stability, increased coating uptake, and increased binding capacity. These ferrofluids have applications in a variety of preparative and diagnostic techniques, including immunoassay, cell separations, toxicity testing, food testing, environmental analysis, and MRI.

Abstract: An oriented polyester film coated on at least one surface with a coating that improves its adhesion to gelatin is disclosed. The dry coating contains one or more sulfopolyesters; one or more tetrablock copolymer resins; and one or more non-volatile polyamines. Other ingredients, such as particulate materials and surfactants, may be present in the coating. The coating is preferably applied at the interdraw stage.

Abstract: A method for the preparation of an immobilized protein ultrathin film reactor by immersing a solid support alternately into an aqueous solution of protein, and into an aqueous solution of polyion charged oppositely to said protein and preparing a structurally controlled ultrathin film of mono- or multi- protein layers on a said solid support with precision at molecular level. And a method for chemical reaction of a substrate by preparing an immobilized protein ultrathin film reactor composed of multiple layers of protein on a solid support by above mentioned method, and initiating a chemical change of the substrate molecules using obtained immobilized protein ultrathin film reactor.

Abstract: A coated packaging material for packaging foodstuffs is prepared with a component mixture of egg white powder, a plasticizer, an emulsifier and water which, by coating mixture weight, are in amounts, respectively, of from about 25% to 30%, 10% to 15%, 2% to 5% and 50% to 63%, the mixture being applied on a packaging material to coat the material and then being heated to coagulate and dry the coating. Upon drying, the coating is made up of from about 60% to 70% heat-coagulated egg white, 25% to 30% plasticizer, 5% to 10% emulsifier and 3% to 8% water. The coated packaging material is employed for packaging a foodstuff so that the coating is positioned between the foodstuff and packaging material.

Abstract: The present invention provides a method for growing or depositing artificial bone materials called organoapatites on a metal surgical alloy. The method involves pretreating the alloy with at least one aqueous solution of a poly(amino acid). After this pretreatment step, the organoapatites can be synthesized onto the alloy. Because most surgical implants are made from metal alloys, this method can be used to make implants which contain organoapatites may promote the formation of natural bone when placed into a human patient in vivo.

Abstract: Coated paper stocks for electrostatic imaging comprising a substrate coated on at least one surface with a resin layer comprised of olefinic material and a pin-hole free, continuous coating layer over said resin layer. The continuous layer has a glass transition temperature above 100.degree. C. and is comprised of one or more natural or synthetic film forming polymers and an anti-static agent. As a single layer this continuous coating layer functions as both a heat protective and imaging layer. In an alternate embodiment two separate coating layers are provided with separate heat protective and imaging functionalities.

Abstract: An applicator implement applies liquid or pasty coating medium directly onto a moving layer of material, in particular paper or cardboard. The applicator implement includes a pre-metering device which extends along the width of the moving material layer. The pre-metering device is divided into a number of segments, each of which are in turn associated with at least one actuator that enables the segments to move with respect to the thickness of the material layer in order to shape a desired profile of the pre-metering device. The applicator implement further includes, following along the path of movement of the material layer, a finishing metering device which also extends along the width of the moving material layer, and which is divided into a number of segments, each of which are in turn associated with at least one actuator that enables the segments to move with respect to the thickness of the material layer in order to shape a desired profile of the finishing metering device.

Abstract: The present invention comprises a polyester film support in which the surface has been subjected to an energetic treatment with nitrogen plasma to produce amine groups on the polyester surface. The treated surface is then coated with a dilute solution of amine reactive hardener and gelatin. After drying the hardener/gelatin coated support a photographic emulsion is coated on the surface. The resulting film element has excellent adhesion of the photographic emulsion after photoprocessing, and it is safer to coat and handle than previously known methods involving grafting of hardener directly to the support.

Abstract: The compound of formula ##STR1## is useful as chain extender in the preparation of polymers, in particular of linear and cross-linkable, heparinizable, biocompatible polymers.

Abstract: Methods and apparatus for evanescent light fluoroimmunoassays are disclosed. The apparatus employs a planar waveguide with an integral semi-cylindrical lens, and has multi-analyte features and calibration features, along with improved evanescent field intensity. A preferred embodiment of the biosensor and assay method have patches of capture molecules each specific for a different analyte disposed adjacent within a single reservoir. The capture molecules are immobilized to the patches on the waveguide surface by site-specific coupling of thiol groups on the capture molecules to photo-affinity crosslinkers which in turn are coupled to the waveguide surface or to a non-specific-binding-resistant coating on the surface. The patches of different antibodies are produced by selectively irradiating a portion of the waveguide surface during the process of coupling the photo-affinity crosslinkers the selective irradiation involving a mask, a laser light source, or the like.

Abstract: A permeable, liquid flow control material composed of: 1) a permeable sheet having a plurality of individual exposed surfaces, at least a portion of which have a surface energy of less than about 45 dynes/cm; and 2) amphiphilic proteins adsorbed onto at least some individual exposed surfaces to define a gradient distribution of amphiphilic protein coating along at least one dimension of the permeable sheet so that the adsorbed amphiphilic protein coating provides controlled wettability along at least one dimension of the liquid flow control material. Desirably, the liquid flow control material is substantially free of fugitive amphiphilic proteins. The material may be used as a permeable, bodyside cover material for absorbent personal care products.

Abstract: A process for coating of an intraocular lens to impart tissue compatibility thereto, comprising the steps: a) priming said lens using a solution of a polyamine; b) coating the lens treated in step a) above with a solution of a periodate-oxidized polysaccharide selected from heparin, heparain sulphate, and chondroitin sulphate to stabilize said polyamine by covalent and/or ionical cross-linking; c) coating the lens treated in step b) above with a solution of a polyamine; and d) coating the lens treated according to step c) above with a solution of a periodate-oxidized polysaccharide selected from heparin, heparain sulphate, and chondroitin sulphate in the presence of a cyanoborohydride to convert formed labile Schiff's bases to stable secondary amines.

Abstract: This invention describes a new approach to three-dimensional molecular tailoring of surfaces. In this process, a plasma deposition step is initially employed to deposit reactive functional groups on the surface of a solid substrate. This is then followed by immersion of the coated substrate in a solution during which time solute molecules react with the functional surface groups introduced during the plasma process. Solute molecules are attached to the surface during this second step. This simple two-step process is of general utility in that both the nature of the plasma introduced surface group and the nature of the solute molecules can be varied. Additionally it is possible to provide exact control of the surface density of reactive groups introduced during the plasma process and thus the concentration of solute molecules coupled to the solid surfaces.

Abstract: A method of applying chemical charge-modifiers to a permeable sheet including the steps of: providing a permeable sheet having a plurality of individual exposed surfaces, at least a portion of which having relatively low surface energies; providing an aqueous solution containing amphiphilic macromolecules, the solution having a relatively high surface tension; contacting the solution containing amphiphilic macromolecules under shear stress conditions with the permeable sheet so that at least a portion of the amphiphilic macromolecules are adsorbed onto at least some individual exposed surfaces to form a coated permeable sheet; and contacting the coated permeable sheet with a solution containing chemical charge modifiers to incorporate chemical charge modifiers onto at least a portion of the amphiphilic macromolecules.

Abstract: Water soluble macromers are modified by addition of free radical polymerizable groups, such as those containing a carbon-carbon double or triple bond, which can be polymerized under mild conditions to encapsulate tissues, cells, or biologically active materials. The polymeric materials are particularly useful as tissue adhesives, coatings for tissue lumens including blood vessels, coatings for cells such as islets of Langerhans, coatings, plugs, supports or substrates for contact with biological materials such as the body, and as drug delivery devices for biologically active molecules.

Abstract: Surfaced-enhanced, analytical procedures wherein a surfaced article includes a substrate surface, metal islands, a spacing/coupling agent layer, and binding partner molecules which bond with work piece molecules to be detected. A population of spaced apart metal islands are formed on the substrate and have at least some interconnections formed between them. A continuous layer coats the islands and all surfaces between the islands. The continuous layer includes a coupling agent which immobilizes first binding partner molecules. The first partner molecules bond to the coupling agent and the second binding partner molecules bind to the first binding partner molecules to allow detection of presence or concentration of the work piece binding partner molecules.

Abstract: A process of making a coated paper comprises the following steps: 1) providing a paper layer composed of a blend of pulp fibers and particulate material containing polyvalent metal cations, 2) applying a acidified alginate solution of a material selected from salts and derivatives of alginic acid to cover at least a portion of the paper, 3) reacting the salts and/or derivatives of alginic acid with polyvalent metal cations in the paper to form a polymer coating, and 4) drying the paper and polymer coating. The permeability of the coated paper is generally at least about 75 percent less than the permeability of an identical uncoated portion of the paper. The solution of alginate material may be partially cross-linked. The alginate solution may be deposited utilizing gravure printing techniques. Also disclosed is a coated paper and a wrapper for a smoking article.

Abstract: A piezoelectric biosensor substrate useful for immobilizing biomolecules in an oriented manner on the surface of a piezoelectric sensor has a ladder polymer of polyacrylonitrile. To make the substrate, a solution of an organic polymer, preferably polyacrylonitrile, is applied to the surface of a piezoelectric sensor. The organic polymer is modifying by heating the polymer in a controlled fashion in air such that a ladder polymer is produced which, in turn, forms the attachment point for the biomolecules comprising the piezoelectric biosensor.

Abstract: An implantable prosthesis comprising an expanded polytetraethylene member having pores present in its wall structure wherein said pores contain a solid insoluble biocompatible, biodegradable material of natural origin. A process of preparing said prostheses is also disclosed.

Abstract: The invention relates to an improved method for the manufacture of magnetically responsive particles, also called ferrofluids. The improved method involves a heat treatment step, which may occur at various times during the preparation of the materials, including during subdivision of the magnetic starting material, during the addion of a coating material, after formation of a magnetically responsive particle, or some combination thereof. The materials formed by such a process have numerous advantages over materials formed by other processes, including enhanced salt stability, increased coating uptake, and increased binding capacity. These ferrofluids have applications in a variety of preparative and diagnostic techniques, including immunoassay, cell separations, toxicity testing, food testing, environmental analysis, and MRI.

Abstract: A method is described to provide a radiographic silver halide material by coating on at least one side of a support, covered with a hydrophobic subbing layer comprising as a latex copolymer vinylidene chloride, methylacrylate and itaconic acid, following hydrophilic layers: at least one gelatinous dye containing layer comprising one or more dyes, at least one silver halide emulsion layer, at least one protective antistress layer, and optionally an afterlayer, characterized in that said hydrophilic layers have a swelling ratio of not more than 200% and in that said hydrophilic layers are coated simultaneously by the slide-hopper coating or by the slide-hopper curtain coating technique.

Abstract: A method for forming an optical device for detecting the presence or amount of an analyte of interest comprising a substrate which supports an optically active layer, an attachment layer provided on the optically active layer, and a receptive layer specific the analyte provided on the attachment layer. The method comprises forming the optically active layer with a chosen refractive index on the substrate by curing the optically active layer on the substrate at a controlled temperature or for a controlled length of time and subsequently providing the attachment and receptive layers on the optically active layer.

Abstract: The present invention relates to a process for producing fibers or a textile product, in which fibers or textile products containing polyurethane fibers are dipped in a water-soluble wool protein solution to selectively adsorb a wool protein on the polyurethane fibers.

Abstract: Insolubilized enzyme particulates are located on the upstream surface of a filtration layer of a filtering element which can be used in a cartridge filter. Employed in a recycling flow reaction system at relatively high flux rates, the cartridges are useful for conducting catalyzed chemical reactions of dissolved solutes, for example, esterifications, isomerizations, oxidations, reductions, and cyclizations.

Abstract: What follows is a description of an invention for the preparation of macroscopic metal surfaces by self assembly of colloidal metal particles. Metal surfaces play a critical role in technology, and in many cases, the surface morphology dictates function. The strategy delineated herein, the use of nanometer scale colloidal particles to form two-dimensional arrays, allows control of surface morphology to a degree previously unattainable and perhaps even unimaginable.

Abstract: Stable suspensions of coated magnetic particles, preferably resuspendable bioactive particles particularly useful in Magnetic Resonance Imaging, are produced by disrupting, what are presumed to be, crystalline agglomerates of a parent particulate magnetic starting material in the presence of a coating material, such that coating can take place during the disruption. The particles are generally coated in suspension yielding a stable suspension of subdivided particles. With the proper selection of a coating material, preferably a protein or other biochemically or biologically active polymer such as an antibody, a resuspendable (colloidal) bioactive product is obtained.

Abstract: Method for producing an optical assay device having a substrate and one or more optical layers, an attachment layer and a receptive layer, including the step of spin coating an anti-reflective layer or an attachment layer.

Abstract: A substrate for surface-enhanced analytical procedures, such substrates prepared for use in specific procedures to detect specific binding partner molecules, and a method for making them. The substrate is a body having a substrate surface on which there are randomly spaced apart metal islands. A continuous layer of coupling agent coats the islands and any intervening substrate surface. First binding partner molecules are bonded to the coupling agent. These are specifically attractive to specified second partner molecules for an analytical procedure for detecting the presence of, and perhaps the concentration of second partner molecules, or in some procedures, of a specified third binding partner molecule which becomes bonded to the second binding partner molecule. The thickness of the coupling agent layer is selected to improve the sensitivity of a given analytical procedure for detecting or measuring the specific binding partner molecule.

Abstract: A method and test kit useful in a wide variety of immunoassay systems. A method of producing metal sol reagents containing metal sol particles of a preselected size is provided. A metal containing solution is reduced under optimized pH conditions to produce metal sol particles of a preselected size, the particles are coated with a coupling compound and then bound with at least one selected immunochemically reactive component. Particles having different immunochemical specificities are also mixed to produce reagents having multiple selected immunochemical specificities.

Abstract: A method is provided for direct coating of transiently stable, colloidal particulate magnetic substrates with various synthetic or naturally-occurring polymers, particularly biologically-active peptides and proteins. The resulting coated resuspendable, colloidal magnetic particles are particularly adapted for use in bioanalytical procedures involving affinity separation, or the like. There is also provided a method for selectively binding chemically-treated colloidal magnetic particles to polyelectrolytes, e.g., to facilitate extraction of nucleic acids from cell lysates.