Xu J.,Center for Advanced Macromolecular Design |
Xu J.,Australian Center for Nanomedicine |
Shanmugam S.,Center for Advanced Macromolecular Design |
Fu C.,Center for Advanced Macromolecular Design |
And 3 more authors.
Journal of the American Chemical Society | Year: 2016
Here, we exploit the selectivity of photoactivation of thiocarbonylthio compounds to implement two distinct organic and polymer synthetic methodologies: (1) a single unit monomer insertion (SUMI) reaction and (2) selective, controlled radical polymerization via a visible-light-mediated photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) process. In the first method, precise single unit monomer insertion into a dithiobenzoate with a high reaction yield (>97%) is reported using an organic photoredox catalyst, pheophorbide a (PheoA), under red light irradiation (γmax = 635 nm, 0.4 mW/cm2). The exceptional selectivity of PheoA toward dithiobenzoate was utilized in combination with another catalyst, zinc tetraphenylporphine (ZnTPP), for the preparation of a complex macromolecular architecture. PheoA was first employed to selectively activate a dithiobenzoate, 4-cyanopentanoic acid dithiobenzoate, for the polymerization of a methacrylate backbone under red light irradiation. Subsequently, metalloporphyrin ZnTPP was utilized to selectively activate pendant trithiocarbonate moieties for the polymerization of acrylates under green light (γmax = 530 nm, 0.6 mW/cm2) to yield well-defined graft co-polymers. © 2016 American Chemical Society.
Basuki J.S.,Australian Center for Nanomedicine |
Duong H.T.T.,Australian Center for Nanomedicine |
MacMillan A.,University of New South Wales |
Whan R.,University of New South Wales |
And 2 more authors.
Macromolecules | Year: 2013
Surface functionalization of superparamagnetic iron oxide nanoparticles (IONPs) was achieved by exploiting a grafting onto approach simultaneously with an in situ modification of the graft block copolymer. Terminal phosphonic-acid-bearing block copolymers composed of pendant-activated ester moieties, that is, poly(pentafluorophenyl acrylate) (P(PFPA)) and poly(oligoethylene glycol acrylate) (P(OEGA)), were synthesized and assembled on IONP surfaces. The assembly was performed in the presence of different primary amines to introduce different functionality to the grafted chains, followed by subsequent thiol-ene Michael additions with acrylates or maleimides to decorate the IONP surface. The aim of this double-click chemistry on the polymer-coated nanoparticles was to generate a library of IONPs consisting of an internal layer of functionalized polyacrylamides and an outer shell of antifouling P(OEGA) decorated with fluorescent ligands. The resultant multifunctionalized IONPs were characterized using ATR-FTIR, XPS and TGA, proving the presence of modified polymers on the IONP surfaces. The functionalized nanoparticles proved to be stable in both water and phosphate buffer containing bovine serum albumin. Zeta potentials of the functionalized nanoparticles could be tuned by the judicious choice of functional groups introduced by the primary amines, for example, spermine, 3-(dimethylamino)-1-propylamine, l-lysine, l-histidine, l-arginine, β-alanine, and taurine. Depending on the pH of IONP dispersions, the charge induced by functional groups within the polymer shell was used to encapsulate ionic dyes (methyl blue and rhodamine 6G in cationic and anionic layers, respectively), serving as models for drug loading via ionic complexation. The attachment of fluorophore through thiol-ene Michael addition was demonstrated by conjugating fluorescein-O-acrylate, as monitored by fluorescence spectroscopy. Cytotoxicity studies revealed that multifunctionalized IONPs were nontoxic to normal human lung fibroblast cell lines. Fluorescence lifetime imaging microscopy was employed to demonstrate the complexation and release of rhodamine 6G dye from l-lysine-functionalized IONPs. © 2013 American Chemical Society.
Liu P.Y.,University of New South Wales |
Erriquez D.,University of Bologna |
Marshall G.M.,University of New South Wales |
Marshall G.M.,Kids Cancer Center |
And 20 more authors.
Journal of the National Cancer Institute | Year: 2014
Background Patients with neuroblastoma due to the amplification of a 130-kb genomic DNA region containing the MYCN oncogene have poor prognoses. Methods Bioinformatics data were used to discover a novel long noncoding RNA, lncUSMycN, at the 130-kb amplicon. RNA-protein pull-down assays were used to identify proteins bound to lncUSMycN RNA. Kaplan-Meier survival analysis, multivariable Cox regression, and two-sided log-rank test were used to examine the prognostic value of lncUSMycN and NonO expression in three cohorts of neuroblastoma patients (n = 47, 88, and 476, respectively). Neuroblastoma-bearing mice were treated with antisense oligonucleotides targeting lncUSMycN (n = 12) or mismatch sequence (n = 13), and results were analyzed by multiple comparison two-way analysis of variance. All statistical tests were two-sided. Results Bioinformatics data predicted lncUSMycN gene and RNA, and reverse-transcription polymerase chain reaction confirmed its three exons and two introns. The lncUSMycN gene was coamplified with MYCN in 88 of 341 human neuroblastoma tissues. lncUSMycN RNA bound to the RNA-binding protein NonO, leading to N-Myc RNA upregulation and neuroblastoma cell proliferation. High levels of lncUSMycN and NonO expression in human neuroblastoma tissues independently predicted poor patient prognoses (lncUSMycN: hazard ratio [HR] = 1.87, 95% confidence interval [CI] = 1.06 to 3.28, P =. 03; NonO: HR = 2.48, 95% CI = 1.34 to 4.57, P =. 004). Treatment with antisense oligonucleotides targeting lncUSMycN in neuroblastoma-bearing mice statistically significantly hindered tumor progression (P <. 001). Conclusions Our data demonstrate the important roles of lncUSMycN and NonO in regulating N-Myc expression and neuroblastoma oncogenesis and provide the first evidence that amplification of long noncoding RNA genes can contribute to tumorigenesis. © 2014 The Author 2014. Published by Oxford University Press. All rights reserved.
Cochran B.J.,University of New South Wales |
Cochran B.J.,Heart Research Institute |
Bisoendial R.J.,University of New South Wales |
Bisoendial R.J.,Heart Research Institute |
And 12 more authors.
Arteriosclerosis, Thrombosis, and Vascular Biology | Year: 2014
Objective - Therapeutic interventions that increase plasma levels of high-density lipoproteins and apolipoprotein A-I (apoA-I) A-I, the major high-density lipoprotein apolipoprotein, improve glycemic control in people with type 2 diabetes mellitus. High-density lipoproteins and apoA-I also enhance insulin synthesis and secretion in isolated pancreatic islets and clonal β-cell lines. This study identifies the signaling pathways that mediate these effects.Approach and Results - Incubation with apoA-I increased cAMP accumulation in Ins-1E cells in a concentration-dependent manner. The increase in cAMP levels was inhibited by preincubating the cells with the cell-permeable, transmembrane adenylate cyclase inhibitor, 2'5' dideoxyadenosine, but not with KH7, which inhibits soluble adenylyl cyclases. Incubation of Ins-1E cells with apoA-I resulted in colocalization of ATP-binding cassette transporter A1 with the Gαs subunit of a heterotrimeric G-protein and a Gαs subunit-dependent increase in insulin secretion. Incubation of Ins-1E cells with apoA-I also increased protein kinase A phosphorylation and reduced the nuclear localization of forkhead box protein O1 (FoxO1). Preincubation of Ins-1E cells with the protein kinase A-specific inhibitors, H89 and PKI amide, prevented apoA-I from increasing insulin secretion and mediating the nuclear exclusion of FoxO1. Transfection of Ins-1E cells with a mutated FoxO1 that is restricted to the nucleus confirmed the requirement for FoxO1 nuclear exclusion by blocking insulin secretion in apoA-I-treated Ins-1E cells. ApoA-I also increased Irs1, Irs2, Ins1, Ins2, and Pdx1 mRNA levels.Conclusions - ApoA-I increases insulin synthesis and secretion via a heterotrimeric G-protein-cAMP-protein kinase A-FoxO1-dependent mechanism that involves transmembrane adenylyl cyclases and increased transcription of key insulin response and β-cell survival genes. © 2014 American Heart Association, Inc.
McCarroll J.,Australian Center for Nanomedicine |
McCarroll J.,University of New South Wales |
Valade D.,University of New South Wales |
Boyer C.,Australian Center for Nanomedicine |
And 8 more authors.
Biomacromolecules | Year: 2011
Poly(ethylene glycol) (PEG) conjugates of Dicer-substrate small interfering RNA (DsiRNA) have been prepared to investigate a new siRNA release strategy. 3'-sense or 5'-antisense thiol-modified, blunt-ended DsiRNAs, inhibiting enhanced green fluorescent protein (eGFP) expression, were covalently conjugated to PEG with varying molecular weights (2, 10, and 20 kg/mol) through a stable thioether bond using a Michael addition reaction. The DsiRNA conjugates with 2 kg/mol PEG (both 3'-sense or 5'-antisense strand conjugated) and the 10 kg/mol PEG conjugated to the 3'-sense strand of DsiRNA were efficiently cleaved by recombinant human Dicer to 21-mer siRNA, as determined by gel electrophoresis. Importantly, 2 and 10 kg/mol PEG conjugated to the 3'-sense strand of DsiRNA showed potent gene silencing activity in human neuroblastoma (SH-EP) cells, stably expressing eGFP, at both the mRNA and protein levels. Moreover, the 10 kg/mol PEG conjugates of the 3'-sense strand of DsiRNA were less immunogenic when compared with the unmodified DsiRNA, determined via an immune stimulation assay on human peripheral blood mononuclear cells. © 2011 American Chemical Society.