Skip to main content

Why Does PEG 400 Co-Encapsulation Improve NGF Stability and Release from PLGA Biodegradable Microspheres?


Purpose. The aim of this work was to understand the mechanism by which co-encapsulated PEG 400 improved the stability of NGF and allowed a continuous release from PLGA 37.5/25 microspheres.

Methods. Microparticles were prepared according to the double emulsion method. PEG 400 was added with NGF in the internal aqueous phase (PEG/PLGA ratio 1/1 and 1.8/1). Its effect was investigated through interfacial tension studies. Protein stability was assessed by ELISA.

Results. A novel application of PEG in protein stabilization during encapsulation was evidenced by adsorption kinetics studies. PEG 400 limited the penetration of NGF in the interfacial film of the primary emulsion. Consequently, it stabilized the NGF by reducing the contact with the organic phase. In addition, it avoided the NGF release profile to level off by limiting the irreversible NGF anchorage in the polymer layers. On the other hand, the amount of active NGF released in the early stages was increased. During microparticle preparation, NaCl could be added in the external aqueous phase to modify the structure of microparticles. This allowed to reduce the initial release rate without affecting the protein stability always encountered in the absence of PEG.

Conclusions. PEG 400 appeared of major interest to achieve a continuous delivery of NGF over seven weeks from biodegradable microparticles prepared by the double emulsion technique.

This is a preview of subscription content, access via your institution.


  1. 1.

    P. J. Camarata, R. Suryanarayanan, D. A. Turner, R. G. Parker, and T. J. Ebner. Sustained release of nerve growth factor from biodegradable polymer microspheres. Neurosurgery 30:313-319 (1992).

    Google Scholar 

  2. 2.

    S. Mittal, A. Cohen, and D. Maysinger. In vitro effects of brain derived neurotrophic factor released from microspheres. Neuroreport 5:2577-2582 (1994).

    Google Scholar 

  3. 3.

    C. E. Krewson, R. Dause, M. Mak, and W. M. Saltzman. Stabilization of nerve growth factor in controlled release polymers and tissue. J. Biomater. Sci. Polym. Ed. 8:103-117 (1996).

    Google Scholar 

  4. 4.

    D. Maysinger, K. Krieglstein, J. Filipovic-Grcic, M. Sendtner, K. Unsicker, and P. Richardson. Microencapsulated ciliary neurotrophic factor: physical properties and biological activities. Exp. Neurol. 138:177-188 (1996).

    Google Scholar 

  5. 5.

    J. M. Péan, M. C. Venier-Julienne, R. Filmon, M. Sergent, R. Phan-Tan-Luu, and J. P. Benoit. Optimization of HSA and NGF encapsulation yields in PLGA microparticles. Int. J. Pharm. 166:105-115 (1998).

    Google Scholar 

  6. 6.

    J. M. Péan, M. C. Venier-Julienne, F. Boury, P. Menei, B. Denizot, and J. P. Benoit. NGF release from poly(d,l-lactide-co-glycolide) microspheres. Effect of some formulation parameters on encapsulated NGF stability. J. Contr. Rel. 56:175-187 (1998).

    Google Scholar 

  7. 7.

    J. Herrmann and R. Bodmeier. The effect of particle microstructure on the somatostatin release from poly(lactide) microspheres prepared by a W/O/W solvent evaporation method. J. Contr. Rel. 36:63-71 (1995).

    Google Scholar 

  8. 8.

    T. Uchida, K. Yoshida, A. Ninomiya, and S. Goto. Optimization of preparative conditions for polylactide (PLA) microspheres containing ovalbumin. Chem. Pharm. Bull. 43:1569-1573 (1995).

    Google Scholar 

  9. 9.

    J. L. Cleland and A. J. S. Jones. Stable formulations of recombinant human growth hormone and interferon-gamma for microencapsulation in biodegradable microspheres. Pharm. Res. 13:1464-1475 (1996).

    Google Scholar 

  10. 10.

    L. Chen, R. N. Apte, and S. Cohen. Characterization of PLGA microspheres for the controlled delivery of IL-1α for tumor immunotherapy. J. Contr. Rel. 43:261-272 (1997).

    Google Scholar 

  11. 11.

    P. Johansen, Y. Men, R. Audran, G. Corradin, H. P. Merkle, and B. Gander. Improving stability and release kinetics of microencapsulated tetanus toxoid by co-encapsulation of additives. Pharm. Res. 15:1103-1110 (1998).

    Google Scholar 

  12. 12.

    J. Nanduri, S. M. Vroegop, S. E. Buxser, and K. E. Neet. Immunological determinants of nerve growth factor involved in p140 trk (Trk) receptor binding. J. Neurosci. Res. 37:433-444 (1994).

    Google Scholar 

  13. 13.

    F. Boury, T. Ivanova, I. Panaïotov, J. E. Proust, A. Bois, and J. Richou. Dilatational properties of adsorbed poly(D,L-lactide) and bovine serum albumin monolayers at the dichloromethane/water interface. Langmuir 11:1636-1644 (1995).

    Google Scholar 

  14. 14.

    J. E. Proust, F. Boury, P. Saulnier, J. P. Benoit, I. Panaïotov, and T. Ivanova. Structure, morphology and degradation of poly(α-hydroxy acid)s microspheres in relation with monolayers. Curr. Top. Coll. Int. Sci. 1:195-224 (1997).

    Google Scholar 

  15. 15.

    F. Boury, H. Marchais, J. E. Proust, and J. P. Benoit. Bovine serum albumin release from poly(α-hydroxy acid) microspheres: effects of polymer molecular weight and surface properties. J. Contr. Rel. 45:75-86 (1997).

    Google Scholar 

  16. 16.

    T. Verrecchia, P. Huve, D. Bazile, M. Veillard, G. Spenlehauer, and P. Couvreur. Adsorption/desorption of human serum albumin at the surface of poly(lactic acid) nanoparticles prepared by a solvent evaporation process. J. Biomed. Mater. Res. 27:1019-1028 (1993).

    Google Scholar 

  17. 17.

    R. R. Almon and S. Varon. Associations of beta nerve growth factor with bovine serum albumin as well as with the alpha and gamma subunits of the 7S macromolecule. J. Neuroch. 30:1559-1567 (1978).

    Google Scholar 

  18. 18.

    T. Arakawa and S. N. Timasheff. Mechanism of poly(ethylene glycol) interaction with proteins. Biochemistry 24:6756-6762 (1985).

    Google Scholar 

  19. 19.

    K. Lim and J. N. Herron. Molecular simulation of protein-PEG interaction. In J. M. Harris (eds), Poly(ethylene glycol) chemistry, biotechnical and biomedical application, Plenum Press, New York, 1992, pp. 29-55.

    Google Scholar 

  20. 20.

    J. M. Harris. Introduction to biotechnical and biomedical applications of poly(ethylene glycol). In J. M. Harris (eds), Poly(ethylene glycol) chemistry, biotechnical and biomedical application, Plenum Press, New York, 1992, pp. 1-12

    Google Scholar 

  21. 21.

    M. Katakam, L. N. Bell, and A. K. Banga. Effect of surfactants on the physical stability of recombinant human growth hormone. J. Pharm. Sci. 84:713-716 (1995).

    Google Scholar 

  22. 22.

    T. G. Park, W. Lu, and G. Crotts. Importance of the in vitro experimental conditions on protein release kinetics, stability and polymer degradation in protein encapsulated poly(D,L-lactic acid-co-glycolic acid) microspheres. J. Contr. Rel. 33:211-222 (1995).

    Google Scholar 

Download references

Author information



Corresponding author

Correspondence to Jean-Pierre Benoit.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Péan, JM., Boury, F., Venier-Julienne, MC. et al. Why Does PEG 400 Co-Encapsulation Improve NGF Stability and Release from PLGA Biodegradable Microspheres?. Pharm Res 16, 1294–1299 (1999).

Download citation

  • NGF
  • PEG
  • PLGA
  • microencapsulation
  • protein stability
  • interfacial tension