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Chan D.P.Y.,00 College Street | Chan D.P.Y.,60 Co | Deleavey G.F.,McGill University | Owen S.C.,00 College Street | And 5 more authors.
Biomaterials | Year: 2013

Efficient and targeted cellular delivery of small interfering RNAs (siRNAs) and antisense oligonucleotides (AONs) is a major challenge facing oligonucleotide-based therapeutics. The majority of current delivery strategies employ either conjugated ligands or oligonucleotide encapsulation within delivery vehicles to facilitate cellular uptake. Chemical modification of the oligonucleotides (ONs) can improve potency and duration of activity, usually as a result of improved nuclease resistance. Here we take advantage of innovations in both polymeric delivery vehicles and ON stabilization to achieve receptor-mediated targeted delivery of siRNAs or AONs for gene silencing. Polymeric nanoparticles comprised of poly(lactide-. co-2-methyl, 2-carboxytrimethylene carbonate)-. g-polyethylene glycol-furan/azide are click-modified with both anti-HER2 antibodies and nucleic acids on the exterior PEG corona. Phosphorothioate (PS), 2'F-ANA, and 2'F-RNA backbone chemical modifications improve siRNA and AON potency and duration of activity. Importantly, delivery of these nucleic acids on the exterior of the polymeric immuno-nanoparticles are as efficient in gene silencing as lipofectamine transfection without the associated potential toxicity of the latter. © 2013 Elsevier Ltd. Source


Chou L.Y.T.,Institute of Biomaterials and Biomedical Engineering | Zagorovsky K.,Institute of Biomaterials and Biomedical Engineering | Chan W.C.W.,Institute of Biomaterials and Biomedical Engineering | Chan W.C.W.,University of Toronto | Chan W.C.W.,00 College Street
Nature Nanotechnology | Year: 2014

The assembly of nanomaterials using DNA can produce complex nanostructures, but the biological applications of these structures remain unexplored. Here, we describe the use of DNA to control the biological delivery and elimination of inorganic nanoparticles by organizing them into colloidal superstructures. The individual nanoparticles serve as building blocks, whose size, surface chemistry and assembly architecture dictate the overall superstructure design. These superstructures interact with cells and tissues as a function of their design, but subsequently degrade into building blocks that can escape biological sequestration. We demonstrate that this strategy reduces nanoparticle retention by macrophages and improves their in vivo tumour accumulation and whole-body elimination. Superstructures can be further functionalized to carry and protect imaging or therapeutic agents against enzymatic degradation. These results suggest a different strategy to engineer nanostructure interactions with biological systems and highlight new directions in the design of biodegradable and multifunctional nanomedicine. © 2014 Macmillan Publishers Limited. All rights reserved. Source


Fiddes L.K.,University of Toronto | Yan N.,University of Toronto | Yan N.,00 College Street
Sensors and Actuators, B: Chemical | Year: 2013

This work outlines a new approach for the construction of a wireless and battery-free broad response vapour sensor. Carbon black/organic polymer composites are known to swell reversibly upon exposure to volatile chemicals. We integrated these types of composites into the electronic elements of a conventional passive RFID tag circuitry to produce resistance changes that result in a change in the RFID tag's output signal frequency and amplitude. To identify vapours, arrays of RFID tags with such vapour-sensing elements were constructed, with each tag containing carbon black as the conducting element and a polymer as the sensing element. The different gas-solid partition coefficients for the polymers in the sensor array produce a unique pattern of signal changes that can be used to classify vapours. This sensor array was able to identify and quantify several vapours of interest (water, ammonia, ethanol and toluene). © 2013 Elsevier Ltd. Source


Ballios B.G.,Kings College | Clarke L.,Kings College | Coles B.L.K.,Kings College | Shoichet M.S.,Kings College | And 2 more authors.
Biology Open | Year: 2012

Self-renewing, multipotential retinal stem cells (RSCs) reside in the pigmented ciliary epithelium of the peripheral retina in adult mammals. RSCs can give rise to rhodopsin positive-cells, which can integrate into early postnatal retina, and represent a potentially useful option for cellular therapy. The ability to purify a stem cell population and direct the differentiation toward a particular cell lineage is a challenge facing the application of stem cells in regenerative medicine. Here we use cell sorting to prospectively enrich mouse RSCs based on size, granularity and low expression of P-cadherin and demonstrate that only rare cells with defined properties proliferate to form colonies.We show that clonally-derived mouse and human RSC progeny are multipotent and can differentiate into mature rhodopsin-positive cells with high efficiency using combinations of exogenous culture additives known to influence neural retinal development, including taurine and retinoic acid. This directed RSC differentiation follows the temporal sequence of photoreceptor differentiation in vivo, and the cells exhibit morphology, protein and gene expression consistent with primary cultures of rods in vitro. These results demonstrate that the RSC, an adult stem cell, can be enriched and directed to produce photoreceptors as a first step toward a targeted cell replacement strategy to treat retinal degenerative disease. © 2012. Published by The Company of Biologists Ltd. Source


Ng A.H.C.,University of Toronto | Ng A.H.C.,Donnelly College | Dean Chamberlain M.,University of Toronto | Dean Chamberlain M.,Donnelly College | And 6 more authors.
Nature Communications | Year: 2015

We report a new technique called Digital microfluidic Immunocytochemistry in Single Cells (DISC). DISC automates protocols for cell culture, stimulation and immunocytochemistry, enabling the interrogation of protein phosphorylation on pulsing with stimulus for as little as 3s. DISC was used to probe the phosphorylation states of platelet-derived growth factor receptor (PDGFR) and the downstream signalling protein, Akt, to evaluate concentration- and time-dependent effects of stimulation. The high time resolution of the technique allowed for surprising new observations - for example, a 10s pulse stimulus of a low concentration of PDGF is sufficient to cause >30% of adherent fibroblasts to commit to Akt activation. With the ability to quantitatively probe signalling events with high time resolution at the single-cell level, we propose that DISC may be an important new technique for a wide range of applications, especially for screening signalling responses of a heterogeneous cell population. © 2015 Macmillan Publishers Limited. Source

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