Engineering the Orientation, Density, and Flexibility of Single-Domain Antibodies on Nanoparticles To Improve Cell Targeting

ACS Appl Mater Interfaces. 2020 Feb 5;12(5):5593-5600. doi: 10.1021/acsami.9b20993. Epub 2020 Jan 22.

Abstract

Nanoparticles targeted to specific cells have the potential to improve the delivery of therapeutics. The effectiveness of cell targeting can be significantly improved by optimizing how the targeting ligands are displayed on the nanoparticle surface. Crucial to optimizing the cell binding are the orientation, density, and flexibility of the targeting ligand on the nanoparticle surface. In this paper, we used an anti-EGFR single-domain antibody (sdAb or nanobody) to target fluorescent nanocrystals (Qdots) to epidermal growth factor receptor (EGFR)-positive cells. The sdAbs were expressed with a synthetic amino acid (azPhe), enabling site-specific conjugation to Qdots in an improved orientation. To optimize the targeting efficiency, we engineered the point of attachment (orientation), controlled the density of targeting groups on the surface of the Qdot, and optimized the length of the poly(ethylene glycol) linker used to couple the sdAb to the Qdot surface. By optimizing orientation, density, and flexibility, we improved cell targeting by more than an order of magnitude. This work highlights the importance of understanding the structure of the nanoparticle surface to achieve the optimal interactions with the intended receptors and how engineering the nanoparticle surface can significantly improve cell targeting.

Keywords: controlled orientation.; nanobody; nanoparticles; noncanonical amino acid; targeted delivery.

MeSH terms

  • A549 Cells
  • Endosomes / metabolism
  • ErbB Receptors / immunology*
  • ErbB Receptors / metabolism
  • Humans
  • Kinetics
  • Lysosomes / metabolism
  • Microscopy, Fluorescence
  • Polyethylene Glycols / chemistry
  • Quantum Dots / chemistry*
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / isolation & purification
  • Single-Domain Antibodies / chemistry*
  • Single-Domain Antibodies / genetics
  • Single-Domain Antibodies / metabolism

Substances

  • Recombinant Proteins
  • Single-Domain Antibodies
  • Polyethylene Glycols
  • ErbB Receptors