The controlled intravenous delivery of drugs using PEG-coated sterically stabilized nanospheres

R. Gref, A. Domb, P. Quellec, T. Blunk, R. H. Müller, J. M. Verbavatz, R. Langer

Research output: Contribution to journalReview articlepeer-review

685 Scopus citations


Injectable blood persistent particulate carriers have important therapeutic application in site-specific drug delivery or medical imaging. However, injected particles are generally eliminated by the reticulo-endothelial system within minutes after administration and accumulate in the liver and spleen. To obtain a coating that might prevent opsonization and subsequent recognition by the macrophages, sterically stabilized nanospheres were developed using amphiphilic diblock or multiblock copolymers. The nanospheres are composed of a hydrophilic polyethylene glycol coating and a biodegradable core in which various drugs were encapsulated. Hydrophobic drugs, such as lidocaine, were entrapped up to 45 wt% and the release kinetics were governed by the polymer physico-chemical characteristics. Plasma protein adsorption was drastically reduced on PEG-coated particles compared to non-coated ones. Relative protein amounts were time-dependent. The nanospheres exhibited increased blood circulation times and reduced liver accumulation, depending on the coating polyethylene glycol molecular weight and surface density. They could be freeze-dried and redispersed in aqueous solutions and possess good shelf stability. It may be possible to tailor "optimal" polymers for given therapeutic applications.

Original languageEnglish
Pages (from-to)215-233
Number of pages19
JournalAdvanced Drug Delivery Reviews
Issue number2-3
StatePublished - Sep 1995
Externally publishedYes


  • Biodegradable polymers
  • Hydrophilic coating
  • Intravenous drug administration
  • Long-circulating nanoparticles
  • Polyethylene glycol
  • Reduced liver accumulation


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