Particle shape enhances specificity of antibody-displaying nanoparticles

Abstract

Monoclonal antibodies are used in numerous therapeutic and diagnostic applications; however, their efficacy is contingent on specificity and avidity. Here, we show that presentation of antibodies on the surface of nonspherical particles enhances antibody specificity as well as avidity toward their targets. Using spherical, rod-, and disk-shaped polystyrene nano-and microparticles and trastuzumab as the targeting antibody, we studied specific and nonspecific uptake in three breast cancer cell lines: BT-474, SK-BR-3, and MDA-MB-231. Rods exhibited higher specific uptake and lower nonspecific uptake in all cells compared with spheres. This surprising interplay between particle shape and antibodies originates from the unique role of shape in determining binding and unbinding of particles to cell surface. In addition to exhibiting higher binding and internalization, trastuzumab-coated rods also exhibited greater inhibition of BT-474 breast cancer cell growth in vitro to a level that could not be attained by soluble forms of the antibody. The effect of trastuzumab-coated rods on cells was enhanced further by replacing polystyrene particles with pure chemotherapeutic drug nanoparticles of comparable dimensions made from camptothecin. Trastuzumab-coated camptothecin nanoparticles inhibited cell growth at a dose 1,000-fold lower than that required for comparable inhibition of growth using soluble trastuzumab and 10-fold lower than that using BSA-coated camptothecin. These results open unique opportunities for particulate forms of antibodies in therapeutics and diagnostics.morphology | nanomedicine | nanotechnology | drug delivery A ntibodies are used routinely in various analytical, diagnostic, and therapeutic applications, including cell and protein sorting (1), in vitro assays (2), in vivo imaging (3), and targeted delivery of therapeutics for the treatment of various diseases, including cancer (4), arthritis (5), and allergies (6). Significant attention has been given to understanding the molecular basis of antibody-antigen interactions (7) as well as to molecular engineering of antibodies to enhance their functions (8). An increasingly larger number of emerging applications of antibodies, however, are based on particulate systems in which antibodies are chemically or physically immobilized on the surface of microor nanoparticles (9-11). Such particulate antibodies are being pursued for targeted drug delivery or imaging. Although the benefits of antibodies in delivering therapeutic carriers to tissues have long been recognized, the effect of carriers themselves on antibody function has been relatively less studied. The function of antibodies that are immobilized on particles depends on the physicochemical properties of underlying particles, including the choice of material, size, surface modification, and shape. Commonly used nanoparticles for immobilizing antibodies include gold (9), iron oxide (12), quantum dots (13, 14), silica (15), polymers including poly(lactide-coglycolic acid) (PLGA) (11, 16) and polystyrene (...

Mammalian cells preferentially internalize hydrogel nanodiscs over nanorods and use shape-specific uptake mechanisms

“…One possible explanation is that for disc-and rod-shaped nanoparticles, larger size provides larger surface-contact areas for multivalent interactions with cell membranes (22,34). This effect may allow larger adhesion forces with particles and increase the probability of initiating cellular uptake.…”

“…Between discoidal and rod-shaped nanoparticles of similar volume, nanodiscs were more efficiently internalized at all time points. Interestingly, Barua et al (22) reported that for nonspecific hydrophobic polystyrene particles, nanorods and nanodiscs have similar uptake in epithelial breast cancer cells. These differences could highlight the effect of hydrophobic versus hydrophilic surfaces as well as cell types evaluated and emphasize the importance of material composition in understanding nanoparticle-mediated intracellular delivery.…”

“…Recent advances in fabrication technologies have enabled generation of shape-specific microparticles and nanoparticles (8-12). These particles, inspired by the diverse, evolutionarily conserved shapes of pathogens and cells, are being used to study the role of carrier shape on cellular internalization, in vivo transport, and organ distribution (6,11,(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23).Despite these pioneering studies, there remains a significant knowledge gap in our fundamental understanding of the interplay between nanoscale shape and size on cellular internalization, especially for clinically relevant polymer-based hydrophilic nanoparticles. Most in vivo drug delivery and imaging applications have proposed the use of nanoparticles with hydrophilic "stealth" surfaces [often achieved through poly(ethylene glycol) (PEG)-based surface modifications] as well as neutral to anionic surface charge, primarily to allow longer in vivo circulation time by reducing protein adsorption and rapid clearance by the reticuloendothelial system (2, 24-27).…”

“…Recent advances in fabrication technologies have enabled generation of shape-specific microparticles and nanoparticles (8-12). These particles, inspired by the diverse, evolutionarily conserved shapes of pathogens and cells, are being used to study the role of carrier shape on cellular internalization, in vivo transport, and organ distribution (6,11,(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23).…”

Using shape effects to target antibody-coated nanoparticles to lung and brain endothelium

“…Iron oxide nanoworms and gold nanorods have been shown to induce higher tumor accumulation (46,47), and gold nanorods have been shown to exhibit reduced macrophage clearance (48). Recent studies also showed the ability of rodshaped particles to bind specifically to cancer cells in vitro (49).…”