Antibody-guided nanoparticles

Solid particles, liquid droplets, gas bubbles, and liquid films between them in colloid systems have been known for decades to possess size-dependent properties that differ from those of the same material in bulk when size is smaller than about 100 nm. Recent advances in physics, chemistry, materials sciences, engineering, and molecular biology, have allowed the development of nanoparticles (size 1 to 100 nm) by combining atoms or molecules one at a time in arrangements that do not occur in nature. Such particles have attracted much attention because of their unique mechanical, electrical and optical properties. This resulted in a renewed interest to various nanoparticles already known for many years, e.g., liposomes, and to the development of new ones, e.g., quantum dots and gold nanoshells. Such particles conjugated to antibodies can improve their binding or/and effector functions or confer new functions, e.g., cytotoxicity, size-dependent fluorescence and light scattering. Compared to engineered antibody based on fusion proteins or chemical conjugates made with other compounds, the nanoparticle-antibody conjugates have the fundamental capability of separating compounds loaded inside the particle, e.g., inside liposomes, from the environment thus avoiding possible toxicity and immunogenicity. In addition, high local concentrations of loaded active substances, e.g., imaging agents, can be achieved. Nanoparticles can also serve as skeletons for construction of multifunctional nanoparticle-antibody conjugates that combine targeting, imaging and therapeutic properties. Thus nanoparticle-antibody conjugates can complement existing diagnostic tools and treatment protocols and offer entirely new possibilities for the diagnosis and treatment of diseases.