SPECT/CT Imaging of Pluronic Nanocarriers with Varying Poly(ethylene oxide) Block Length and Aggregation State

Mol Pharm. 2016 Mar 7;13(3):1158-65. doi: 10.1021/acs.molpharmaceut.5b00958. Epub 2016 Feb 25.


Optimal biodistribution and prolonged circulation of nanocarriers improve diagnostic and therapeutic effects of enhanced permeability and retention-based nanomedicines. Despite extensive use of Pluronics in polymer-based pharmaceuticals, the influence of different poly(ethylene oxide) (PEO) block length and aggregation state on the biodistribution of the carriers is rather unexplored. In this work, we studied these effects by evaluating the biodistribution of Pluronic unimers and cross-linked micelles with different PEO block size. In vivo biodistribution of (111)In-radiolabeled Pluronic nanocarriers was investigated in healthy mice using single photon emission computed tomography. All carriers show fast uptake in the organs from the reticuloendothelial system followed by a steady elimination through the hepatobiliary tract and renal filtration. The PEO block length affects the initial renal clearance of the compounds and the overall liver uptake. The aggregation state influences the long-term accumulation of the nanocarriers in the liver. We showed that the circulation time and elimination pathways can be tuned by varying the physicochemical properties of Pluronic copolymers. Our results can be beneficial for the design of future Pluronic-based nanomedicines.

Keywords: Pluronic; SPECT; micelles; unimers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Drug Carriers*
  • Indium Radioisotopes / administration & dosage
  • Indium Radioisotopes / chemistry
  • Indium Radioisotopes / pharmacokinetics
  • Mice
  • Mice, Inbred A
  • Micelles
  • Molecular Imaging / methods*
  • Nanoparticles / administration & dosage
  • Nanoparticles / chemistry*
  • Poloxamer / chemistry*
  • Polyethylene Glycols / chemistry*
  • Polymers / chemistry
  • Tissue Distribution
  • Tomography, Emission-Computed, Single-Photon / methods*
  • Tomography, X-Ray Computed / methods*


  • Drug Carriers
  • Indium Radioisotopes
  • Micelles
  • Polymers
  • Poloxamer
  • Polyethylene Glycols