(168a) Water-in-Water Emulsion Based Synthesis of Hydrogel Nanospheres with Tunable Release Properties

Poly(ethylene glycol)
(PEG) micro/nanospheres have several unique
advantages as polymer based drug delivery systems (DDS) such as tunable size,
large surface area to volume ratio, and colloidal stability. Emulsification is
one of the widely used methods for facile synthesis of micro/nanospheres. Two-phase aqueous
system based on polymer-polymer immiscibility is a novel approach for
preparation of water-in-water (w/w) emulsions. This method is promising for the
synthesis of PEG micro/nanospheres for biological
systems, since the emulsion is aqueous and do not require organic solvents or
surfactants. Here, we report the synthesis of nano-scale
PEG hydrogel particles using w/w emulsions using phase separation of dextran
and PEG prepolymer. Dynamic light scattering (DLS)
and scaning electron microscopy (SEM) results
demonstrated that nano-scale hydrogel spheres could
be obtained with this approach (Figure 1). We investigated the release
kinetics of a model drug, pregabalin (PGB) from PEG nanospheres and demonstrated the influence of
polymerization conditions on loading and release of the drug as well as the
morphology and size distribution of PEG nanospheres.
The experimental drug release data was fitted to a stretched exponential
function which suggested high correlation with experimental results to predict
half-time and drug release rates from the model equation. The biocompatibility
of nanospheres on human dermal fibroblasts using
cell-survival assay suggested that PEG nanospheres
with altered concentrations are non-toxic, and can be considered for controlled
drug/molecule delivery. 

 SHAPE  \* MERGEFORMAT

Fig. 1. a)
Two-phase separation of dextran-PEG polymer b) Light microscope image of
dextran-PEG w/w emulsion (scale bar: 40 µm) c) SEM image of dried PEG (scale
bar: 1 µm)