Alan Rembaum

Synthesis and Reactions of Hydrophilic Functional Microspheres for Immunological Studies

Abstract There is a need for hydrophilic polymeric microspheres with functional groups on their surface which can be reacted efficiently with proteins. These microspheres with antibodies (immunoglobulins) covalently bound to their surfaces constitute valuable immunoreagents capable of marking specific receptors (antigens) on cell surface membranes. The main requirements of the microspheres for the above applications are: insolubility in aqueous or organic media, absence of aggregation and of nonspecific interaction with cells and presence of suitable functional groups for covalent binding with antibodies. Hydrophobic polystyrene or poly(methyl methacrylate) latices do not meet these requirements. Copolymerization of hydrophilic monomers under suitable experimental conditions yielded microspheres with the required characteristics. Emulsion polymerization and ionizing radiation were found to constitute convenient techniques for the synthesis of hydrophilic and crosslinked (and therefore insoluble) functiona...

Synthesis and Properties of a New Class of Potential Biomedical Polymers

Abstract Both low molecular weight compounds and some polyelectrolytes containing quaternary nitrogen atoms in their structure have been known for some time to possess important biological activity. Aliphatic ammonium compounds are used as bacteriocides and muscle relaxants, and quinolinium compounds have recently been found to be excellent antileukemic agents. In addition, a considerable amount of evidence has been accumulated to show that organic ammonium salts combine with heparin, and the resulting complex may be used as a coating to render polymers blood-compatible. However, the introduction of ammonium groups into the backbone of a polymer exhibiting good mechanical properties offers certain advantages.

Electrophoretic cell separation by means of microspheres

The electrophoretic mobility of fixed human erythrocytes immunologically labeled with poly(vinylpyridine) or poly(glutaraldehyde) microspheres was reduced by approximately 40%. This observation was utilized in preparative scale electrophoretic separations of fixed human and turkey erythrocytes, the mobilities of which under normal physiological conditions do not differ sufficiently to allow their separation by continuous flow electrophoresis. We suggest that resolution in the electrophoretic separation of cell subpopulations, currently limited by finite and often overlapping mobility distributions, may be significantly enhanced by immunospecific labeling of target populations using microspheres.

Sedimentation Equilibrium of High Charge Density Cationic Polyelectrolytes

Although a number of theoretical treatments and applications of sedimentation equilibrium have been reported in recent years (1–9), as yet no systematic theory or method is available for the study of nonideal, polydisperse polyelectrolyte systems. In view of the increasing importance of polycations in polymer chemistry, microbiology, and industry, the development of convenient, reliable methods of physical characterization of polycationic polymer preparations has become an immediate problem. The analytical ultracentrifuge, by virtue of the wide range of operating conditions accessible (from 800 to 68,000 rpm) and the sensitivity of the available optical systems is an excellent candidate for the nucleus of a routine, high-precision system of polymer molecular-weight determination. The molecular weights accessible by current centrifuge methods range over nearly four orders of magnitude from several thousand to the tens of millions. The ability of the analytical ultracentrifuge to handle concentrations of samples as low as 0.05% (in some cases, lower) allow concentration-dependent studies to be extrapolated with reliability into the zero concentration range.