Nanoparticle Loading Induced Morphological Transitions and Size Fractionation of Coassemblies from PS-b-PAA with Quantum Dots

Abstract

Inorganic nanoparticles play a very important role in the fabrication and regulation of desirable hybrid structures with block copolymers. In this study, polystyrene-b-poly(acrylic acid) (PS48-b-PAA67) and oleic acid-capped CdSe/CdS core/shell quantum dots (QDs) are coassembled in tetrahydrofuran (THF) through gradual water addition. QDs are incorporated into the hydrophilic PAA blocks because of the strong coordination between PAA blocks and the surface of QDs. Increasing the weight fraction of QDs (ω = 0-0.44) leads to morphological transitions from hybrid spherical micelles to large compound micelles (LCMs) and then to bowl-shaped structures. The coassembly process is monitored using transmission electron microscopy (TEM). Formation mechanism of different morphologies is further proposed in which the PAA blocks bridging QDs manipulates the polymer chain mobility and the resulting morphology. Furthermore, the size and size distribution of assemblies serving as drug carriers will influence the circulation time, organ distribution and cell entry pathway of assemblies. Therefore, it is important to prepare or isolate assemblies with monodisperse or narrow size distribution for biomedical applications. Here, the centrifugation and membrane filtration techniques are applied to fractionate polydisperse coassemblies, and the results indicate that both techniques provide effective size fractionation.

Assembly and Characterizations of Bifunctional Fluorescent and Magnetic Microneedles With One Decade Length Tunability

“…Tuning of Length : Out of the 15 investigated compositions, our imaging setup allowed for the estimation of the length distribution of 11 samples (Figure b). Each of those distributions had a log‐normal profile, consistently with what has previously been observed for supracolloidal aggregates and colloidosomes (Figure e, and Figures S13–S15, Supporting Information) . Mapping the Z ratio over the ternary diagram reveals that the length decreases with increasing Z , with the geometric mean length ranging from 5.7 to 48.5 µm for Z = 6.03 to 1.21 respectively.…”

Morphological transition of amphiphilic block copolymer/PEGylated phospholipid complexes induced by the dynamic subtle balance interactions in the self-assembled aggregates

“…Although self-assembly behavior of amphiphilic block copolymers in aqueous solution has been well understood and the effective rules have been developed to guide scientists to synthesize suitable copolymers to obtain the desired self-assembled structures (12)(13)(14)(15), it is still a challenge to control the morphological transition of self-assembly structures effectively and conveniently. Recently, some studies on the development of nanoparticle/amphiphilic block copolymer nanocomposites indicate that the incorporation of nanoparticles in a polymeric matrix may be used to manipulate the morphological transition of amphiphilic block copolymer aggregates by varying the relative volume ratio of hydrophobic block/hydrophilic block (16)(17)(18). Co-assembly of nanoparticle and amphiphilic block copolymer can give rise to different functional nanostructures with extensive applications in biomedical fields.…”

Shape-Anisotropic Diblock Copolymer Particles with Varied Internal Structures

“…Polymeric particles have attracted much attention due to their potential applications in photonics, biomedicine, , nanoreactors, catalysis, and other fields. − Generally, particles’ shape and internal structure can significantly influence their properties and functional behavior. For example, amphiphilic Janus particles have a larger adsorption energy to an oil–water interface compared with their homogeneous counterparts and thus can be used as particle surfactants for stabilizing emulsions .…”