Pharmaceutical Research

, Volume 26, Issue 1, pp 244–249

Shape Induced Inhibition of Phagocytosis of Polymer Particles

Drug Delivery and Targeting

DOI: 10.1007/s11095-008-9626-z

Cite this article as:
Champion, J.A. & Mitragotri, S. Pharm Res (2009) 26: 244. doi:10.1007/s11095-008-9626-z



To determine if particle shape can be engineered to inhibit phagocytosis of drug delivery particles by macrophages, which can be a significant barrier to successful therapeutic delivery.


Non-spherical polystyrene particles were fabricated by stretching spherical particles embedded in a polymer film. A rat alveolar macrophage cell line was used as model macrophages. Phagocytosis of particles was assessed using time-lapse video microscopy and fluorescence microscopy.


We fabricated worm-like particles with very high aspect ratios (>20). This shape exhibits negligible phagocytosis compared to conventional spherical particles of equal volume. Reduced phagocytosis is a result of decreasing high curvature regions of the particle to two single points, the ends of the worm-like particles. Internalization is possible only at these points, while attachment anywhere along the length of the particles inhibits internalization due to the low curvature.


Shape-induced inhibition of phagocytosis of drug delivery particles is possible by minimizing the size-normalized curvature of particles. We have created a high aspect ratio shape that exhibits negligible uptake by macrophages.


aspect ratio curvature drug delivery macrophage polystyrene 

Supplementary material

11095_2008_9626_MOESM1_ESM.doc (640 kb)
Supplementary Material(DOC 654 kb)

Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  1. 1.Department of Chemical EngineeringUniversity of CaliforniaSanta BarbaraUSA
  2. 2.Department of Chemical EngineeringCalifornia Institute of TechnologyPasadenaUSA

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