Precise control of quantum dot location within the P3HT-b-P2VP/QD nanowires formed by crystallization-driven 1D growth of hybrid dimeric seeds.

Herein, we report a simple fabrication of hybrid nanowires (NWs) composed of a p-type conjugated polymer (CP) and n-type inorganic quantum dots (QDs) by exploiting the crystallization-driven solution assembly of poly(3-hexylthiophene)-b-poly(2-vinylpyridine) (P3HT-b-P2VP) rod-coil amphiphiles. The visualization of the crystallization-driven growth evolution of hybrid NWs through systematic transmission electron microscopy experiments showed that discrete dimeric CdSe QDs bridged by P3HT-b-P2VP polymers were generated during the initial state of crystallization. These, in turn, assemble into elongated fibrils, forming the coaxial P3HT-b-P2VP/QDs hybrid NWs. In particular, the location of the QD arrays within the single strand of P3HT-b-P2VP can be controlled precisely by manipulating the regioregularity (RR) values of P3HT block and the relative lengths of P2VP block. The degree of coaxiality of the QD arrays was shown to depend on the coplanarity of the thiophene rings of P3HT block, which can be controlled by the RR value of P3HT block. In addition, the location of QDs could be regulated at the specific-local site of P3HT-b-P2VP NW according to the surface characteristics of QDs. As an example, the comparison of two different QDs coated with hydrophobic alkyl-terminated and hydroxyl-terminated molecules, respectively, is used to elucidate the effect of the surface properties of QDs on their nanolocation in the NW.

Three-dimensional analysis of abnormal ultrastructural alteration in mitochondria of hippocampus of APP/PSEN1 transgenic mouse.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder. The deterioration of subcellular organelles, including the mitochondria, is another major ultrastructural characteristic of AD pathogenesis, in addition to amyloid plaque deposition. However, the three-dimensional (3-D) study of mitochondrial structural alteration in AD remains poorly understood. Therefore, ultrastructural analysis, 3-D electron tomography, and immunogold electron microscopy were performed in the present study to clarify the abnormal structural alterations in mitochondria caused by the progression of AD in APP/PSEN1 transgenic mice, expressing human amyloid precursor protein, as a model for AD. Amyloid beta (A beta) plaques accumulated and dystrophic neurites (DN) developed in the hippocampus of transgenic AD mouse brains. We also identified the loss of peroxiredoxin 3, an endogenous cytoprotective antioxidant enzyme and the accumulation of A beta in the hippocampal mitochondria of transgenic mice, which differs from those in age-matched wild-type mice. The mitochondria in A beta plaque-detected regions were severely disrupted, and the patterns of ultrastructural abnormalities were classified into three groups: disappearance of cristae, swelling of cristae, and bulging of the outer membrane. These results demonstrated that morpho-functional alterations of mitochondria and AD progression are closely associated and may be beneficial in investigating the function of mitochondria in AD pathogenesis.

Organic-inorganic vesicular hybrids driven by assembly of dendritic amphiphiles: site-selective encapsulation of nanoparticles.

The amphiphilic block codendrimer self-assembled into supramolecular vesicles with a bilayer membrane in both hydrophilic and hydrophobic solvents. Surface-modified quantum dots (QDs) were successfully entrapped within the wall of vesicles through a simple self-assembly process without any structural disruption.