Polyacrolein microspheres as immunoreagents

Design of folic acid-conjugated nanoparticles for drug targeting

The new concept developed in this study is the design of poly(ethylene glycol) (PEG)-coated biodegradable nanoparticles coupled to folic acid to target the folate-binding protein; this molecule is the soluble form of the folate receptor that is overexpressed on the surface of many tumoral cells. For this purpose, a novel copolymer, the poly[aminopoly(ethylene glycol)cyanoacrylate-co-hexadecyl cyanoacrylate] [poly(H(2)NPEGCA-co-HDCA)] was synthesized and characterized. Then nanoparticles were prepared by nanoprecipitation of the obtained copolymer, and their size, zeta potential, and surface hydrophobicity were investigated. Nanoparticles were then conjugated to the activated folic acid via PEG terminal amino groups and purified from unreacted products. Finally, the specific interaction between the conjugate folate-nanoparticles and the folate-binding protein was evaluated by surface plasmon resonance. This analysis confirmed a specific binding of the folate-nanoparticles to the folate-binding protein. This interaction did not occur with nonconjugated nanoparticles used as control. Thus, folate-linked nanoparticles represent a potential new drug carrier for tumor cell-selective targeting.

Synthesis of new hydrophilic microspheres: optimized carriers for microparticle-enhanced nephelometric immunoassays

To optimize antigen-antibody reactions, we have synthesized chemically well-defined hydrophilic microspheres. Proteins or haptens were covalently linked to these carriers. When the microsphere conjugates were agglutinated by the corresponding antiserum, the size of the complex artificially increased during the immunological reaction. After optimizing various parameters such as the hydrophilic character, repulsion charges, and amount of antigen coupled to the microspheres, we developed a rapid and sensitive immunoassay based on laser light scattering by the complexes.

Antigen-presenting cell function of dendritic cells and macrophages in proliferative T cell responses to soluble and particulate antigens

The capacity of dendritic cells (DC) and macrophages (M phi) to present soluble and particulate antigen was tested in an ovalbumin (OVA)-specific T cell proliferation assay. In a comparative investigation we found that both DC and M phi were able to present soluble OVA, but that only M phi could present insolubilized OVA to T cells. DC were found to be able to present OVA in collaboration with M phi. The failure of DC to present insolubilized OVA is probably caused by their inability to endocytose these antigens. DC appeared not to endocytose substantial amounts of soluble OVA either. In contrast to M phi, antigen presentation by DC is not blocked by lysosomotropic drugs. Taken together, these observations suggest that DC can present soluble protein antigens without intracellular degradation.

Magnetic albumin/protein A immunomicrospheres. I. Preparation, antibody binding capacity and chemical stability

We describe a method of preparing small magnetic microspheres of albumin/protein A, uniform in size, at 200, 300 or 500 nm. It is shown that, independent of size, the microspheres always carry iron peripherally in their matrix and are thus magnetically responsive. A quantitative antibody binding capacity of 82 micrograms/mg microspheres was established for the 500 nm microspheres. The microspheres are stable in most commonly used buffers over a pH range of 2.5-9.2, but are appreciably unstable in such concentrated denaturing agents as 3 M TCN-, 6 M guanidine, or 8 M urea (loss of antibody binding capacity, 30% for TCN- and 70% for urea).