Branched Polyethyleneimine / Hyaluronic Acid Complex Coacervates Studied by SECM

6th Baltic Electrochemistry Conference, Helsinki, 15th – 17th June, 2016

Branched polyethyleneimine / hyaluronic acid complex coacervates studied by SECM

Maija Huuppola1*, Kirsi Yliniemi1, Emmanuelle Morin-Picardat2, Arto Urtti2 and Lasse Murtomäki1

1 Department of Chemistry, Aalto University School of Chemical Technology, P.O. Box 16100, FI-00076 Aalto, Finland

2 School of Pharmacy, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland

* Presenting Author:

abstract

Branched polyethyleneimine (bPEI) is widely studied cationic polyelectrolyte in medical research. Especially its use in gene delivery is currently heavily investigated as it can bind with negatively charged DNA creating bPEI/DNA complexes [1]. Also, bPEI can form netlike structures, complex coacervates [2], with anionic counterparts, such as hyaluronic acid (HA), and such complexes are interesting for drug delivery studies. In both of these cases, the protonation degree of bPEI is crucial for the binding affinity which in turn controls the stability and release of the drug or DNA. Thus, information concerning the breaking of bPEI containing complexes is vital for its possible use in medical applications.

In this work, the dissolution of bPEI/HA complex coacervates is studied by scanning electrochemical microscope SECM (as shown in Fig. 1). The results show that the bPEI/HA stability can be tuned with the formation pH. The bPEI/HA complex coacervates formed at near neutral pH are more stable and dissolve at pH=10 or higher while the complexes formed in more alkaline environments can be dissolved in the physiologically relevant pH range. This behavior is explained by the protonation degree of bPEI which dictates its affinity to HA: at higher pH values the protonation degree is lower, resulting in the formation of easily soluble complex coacervates.

Fig. 1. Left: measurement set-up, right: example of SECM results showing the complex coacervate dissolution.

REFERENCES

[1] R. Bansal, K.C. Gupta, P. Kumar, Biodegradable and versatile polyethyleneimine derivatives efficiently transfer DNA and siRNA into mammalian cells, Colloids Surf., B 135 (2015) 661-668.

[2] D. Priftis, K. Megley, N. Laugel, M. Tirrell, Complex coacervation of poly(ethylene-imine)/polypeptide aqueous solutions: Thermodynamic and rheological characterization, J. Colloid Interface Sci. 398 (2013) 39-50.