Biodegradable Blend Nanoparticles of Amphiphilic Diblock Copolymers Prepared by Nano-Precipitation Method

Abstract

Nanoparticles of biodegradable methoxy poly(ethylene glycol)-b-polyester amphiphilic diblock copolymers have widely investigated for use as controlled release drug delivery carriers. In this work, blend nanoparticles of methoxy poly(ethylene glycol)-b-poly(D,L-lactide) (MPEG-b-PDLL) and methoxy poly(ethylene glycol)-b-poly(-caprolactone) (MPEGb-PCL) were prepared by nano-precipitation method without any surfactants. H-NMR spectra showed significant difference in integral peak areas, suggesting the nanoparticles with different MPEG-b-PDLL/MPEG-b-PCL blend ratios can be prepared. Transmission electron microscope revealed the blend nanoparticles had nearly spherical in shape with smooth surface. Average size of the blend nanoparticles obtained from light-scattering analysis slightly decreased with increase in blend ratio of MPEG-b-PCL. The MPEG-b-PDLL and MPEG-b-PCL were amorphous and semi-crystalline, respectively. Thermal transition properties of the blend nanoparticles were studied with differential scanning calorimetry (DSC). The DSC results showed that glass transition temperatures of the blend nanoparticles decreased and heats of melting steadily increased, while the melting temperature did not change as the MPEG-b-PCL blend ratio increased. This indicates the miscibility of MPEG-b-PDLL and MPEG-b-PCL in the amorphous

Aptamer-modified polymer nanoparticles for targeted drug delivery

“…This results in a shrinking of the PEG shell of the particles. This observation has already been described in literature [28][29][30].…”