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Scale-up of Functional Biocompatible Polymers for Surface Modification of Nanomaterials

Presented by Dr. Donghun Koo at the Society for Biomaterials Annual Meeting in Denver, Colorado on April 16-19, 2014.

By: Donghun Koo, Gangadhar Panambur, Sebastian Grajales, Viktor Balema, Sigma-Aldrich Corporation, 6000 N. Teutonia Avenue, Milwaukee, 53209

Scope of work

  • Improve economy of functional polylactides1
  • Develop a new one-pot synthetic procedure for target polymers
  • Scale up and optimize polymerization of thiol-end biocompatible Polylactides


Functional biocompatible polymers enable the use of inorganic nanomaterials in the field of biomedical applications2

Thiol end-functionalized Polylactides were initially used by Hou to generate  surface-modified quantum dots3 with

  • Improved  biocompatibility
  • Reduced concentration of surface defects
  • Enhanced photoluminescent stability and quantum yield

Further developments widen the scope to other biocompatible polymers in imaging/diagnostics2 with

  • Enhanced MRI response of magnetic nanoparticles
  • Enabled fluorescent imaging of nanomaterials
  • Increased biocompatibility of inorganic nanoparticles

Synthesis of Well-defined Thiol–end Polylactides

  • Scale up to 1 Kg (Milwaukee site)
  • Temperature:  60ºC


  • Reduction process immediately after polymerization without polymer precipitation

Figure 1. 1H NMR spectrum of HS-PLLA-OH


Table 1. Proven reproducibility by 1H NMR and GPC

Development Run Theoretical Mn Mn by NMR Mn by GPC a PDI
1 2,500 2,400 2,800 1.12
2 2,500 2,300 2,700 1.15
2 2,500 2,400 2,800 1.13

a GPC data were converted by a factor of 0.58 4


  • High purity; no disulfide detected
  • One-pot synthesis was successfully completed
  • Excellent reproducibility (tracked by GPC and 1H NMR)
  • Cost reduction by 50%



Further Scale-up: Functional Polymers for Biomedical Applications

  • Well-defined Polylactides and Polycaprolactones
  • Copolymers: PLA-PMAC, PLA-PAA, PLGA and PLGA-PEG
  • Applications: Click Chemistry, CRP, Drug Delivery and Tissue Engineering
  • Customized solutions




  1. Koo D. et al., Polym. Chem. 2012, 3, 718 – 726.
  2. Oh J.K. et al., Soft Matter 2011, 7, 5096 – 5108.
  3. Hou X. et al., Macromol. Biosci. 2009, 9, 551 – 562.
  4. Kowalski A. et al., Macromolecules 1998, 31, 2114 – 2122.


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