Polymer Buffer Research Articles

Nephelometric Detection of Soluble Immune Complexes: Methodology and Clinical Applications

We have developed a method for the detection of immune complexes by laser nephelometry which is simple, reproducible, suitable for automation, and generally adaptable for diagnostic testing. Light dispersion by antigen-antibody complexes in the test samples is measured after addition of polymeric buffer, which enhances the aggregation of complexes but does not significantly affect unbound immunoglobulins. The method was used to measure immune complexes formed in vitro by incubation of tetanus toxoid with serum from a rabbit previously hyperimmunized with the same antigen, and to compare the levels of immune complexes in human sera obtained from normal adults and from 37 patients with collagen vascular diseases or endocarditis. When precautions were taken to avoid interference produced by the presence of lipoproteins or by freezing of the samples, the results obtained with human sera were consistent with those expected for normal controls and for patients with conditions thought to be associated with the presence of soluble immune complexes.

Controlled drug release by polymer dissolution. I. Partial esters of maleic anhydride copolymers—properties and theory

AbstractThe kinetics of drug release from a series of partial esters of vinyl acetate–maleic anhydride has been investigated. These polymers in their un‐ionized forms are hydrophobic and water insoluble, but in their ionized forms they are water soluble. Polymer dissolution is pH sensitive, and different half‐esters have a characteristic pH range above which they are soluble and below which they are insoluble. When films are placed in buffered media, they erode at a constant rate that depends on the pH of dissolution of the polymer and on the pH of the buffered medium. Dissolution of the polymer is limited to the polymer–buffer medium interface, and drugs dissolved or uniformly dispersed in the polymer are released by zero‐order kinetics. A detailed model has been developed that successfully correlates dissolution behavior and various experimental parameters.