Research

Thrust I. SRD-based biomaterials

The design and development of multifunctional nanoscale devices able to interface with biological processes are centered in current nanobiotechnology. Stimuli-responsive degradation (SRD) or cleavage of dynamic covalent bonds in response to external stimuli is a promising platform for the development of polymer-based multifunctional nanomaterials. These nanomaterials are designed to degrade upon the cleavage of dynamic linkages in response to single or multi-stimuli, thus tuning lower critical solution temperature, controlling nanoparticle morphologies, fabricating highly-ordered nanopores, and enhancing controlled drug release. With promising dynamic disulfide chemistry as an initial thrust, we develop stimuli-responsive degradable nanomaterials, typically including thermoresponsive polymers and hydrogels for tissue engineering, fibrous mesh for vascular surgery, crosslinked nanogels and self-assembled nanocarriers for multi-response drug delivery.

Selected publications for nanogels

• Y. Wen,^# J. K. Oh.* Dual-stimuli reduction and acidic pH-responsive bionanogels: intracellular delivery nanocarriers with enhanced release. RSC Adv. 2014, 4, 229-237.
• J. K. Oh,* R. Drumright, D. J. Siegwart, K. Matyjaszewski. The development of microgels/nanogels for drug delivery applications. Prog. Polym. Sci. 2008, 33, 448-477.
• J. K. Oh, D. J. Siegwart,^# H. Lee, G. Sherwood, L. Peteanu, J. O. Hollinger, K. Kataoka, K. Matyjaszewski. Biodegradable nanogels prepared by atom transfer radical polymerization as potential targeted delivery carriers: Synthesis, degradation, in vitro release, and bioconjugation. J. Am. Chem. Soc. 2007, 129, 5939-5945.
• J. K. Oh, C. Tang, H. Gao, N. V. Tsarevsky, K. Matyjaszewski. Inverse miniemulsion ATRP: A new method for synthesis and functionalization of well-controlled water-soluble/crosslinked particles. J. Am. Chem. Soc. 2006, 128, 5578-5584.

Selected publications for thermoresponsive polymers, hydrogels, and fibers

• N. Chan, S. Y. An, N. Yee, J. K. Oh.* Dual redox and thermo-responsive double hydrophilic block copolymers with tunable thermoresponsive properties and self-assembly behavior. Macromol. Rapid Commun. 2014, 35, 752-757.
• K. Rahimian-Bajgiran, N. Chan, Q. Zhang, S. M. Noh, H. I. Lee, J. K. Oh.* Tuning LCST with thiol-responsiveness of thermoresponsive copolymers containing pendant disulfides. Chem. Commun. 2013, 49, 807-809.
• Q. Zhang, S. M. Noh, J. H. Nam, H. W. Jung, J. M. Park, J. K. Oh.* Dual temperature and thiol-responsive POEOMA-multisegmented polydisulfides: synthesis and thermoresponsive properties. Macromol. Rapid Commun. 2012, 33, 1528-1534.
• N. R. Ko, G. Sabbatier, A. Cunningham, G. Laroche, J. K. Oh.* Air-spun PLA fibers modified with reductively-sheddable hydrophilic surfaces for vascular tissue engineering: synthesis and surface modification. Macromol. Rapid Commun. 2014, 35, 447-453.

SRD-based ABPs and their assemblies/drug delivery

Nanomaterials based on well-defined amphiphilic block copolymers, particularly micelles, have offered a broad choice of materials for targeted drug delivery and imaging platforms. However, it has been an ongoing, complex challenge to offer controlled release of anticancer therapeutics in targeted cells for the detection, diagnosis, and treatment of cancers. Controlled release can enhance therapeutic efficacy and reduce the side effects common to small drugs. We develop various strategies to synthesize novel micelles with disulfide linkages positioned at different single locations, as in the micellar core, in the interlayered corona, or at the interface, as well as recently at multiple locations. These developed strategies enable the investigation of structure-property relationship between morphological variance and stimuli-responsive degradation. Ultimately, the results enable the optimization of degradable micelles offering enhanced release inside diseased cells, particularly targeted cancer cells.

Selected publications

• N. Ko, J. K. Oh.* Glutathione-triggered disassembly of dual disulfide located degradable nanocarriers of polylactide-based block copolymers for rapid drug release. Biomacromolecules 2014, 15, 3180-3189.
• N. Chan,^# S. Y. An.^# J. K. Oh.* Dual location disulfide degradable interlayer-crosslinked micelles with extended sheddable coronas exhibiting enhanced colloidal stability and rapid release. Polym. Chem. 2014, 5, 1637-1649.
• N. Chan, B. Khorsand, S. Aleksanian, J. K. Oh.* Dual location stimuli-responsive degradation strategy of block copolymer nanocarriers for accelerated release. Chem. Commun. 2013, 49, 7534-7536.
• B. Khorsand, G. Lapointe, C. Brett, J. K. Oh.* Intracellular drug delivery nanocarriers of glutathione-responsive degradable copolymers having pendant disulfide linkages. Biomacromolecules 2013, 14, 2103-2111.
• Q. Zhang,^# S. Aleksanian,^# S. M. Noh, J. K. Oh.* Thiol-responsive block copolymer nanocarriers exhibiting tunable release with morphology changes. Polym. Chem. 2013, 4, 351-359.
• A. Cunningham,^# J. K. Oh.* New Design of Thiol-responsive Degradable Block Copolymer Micelles. Macromol. Rapid Commun. 2013, 34, 163-168.
• Q. Zhang, N. R. Ko, J. K. Oh.* Recent advances of stimuli-responsive degradable block copolymer micelles: synthesis and controlled drug delivery applications. Chem. Commun. 2012, 48, 7542-7552.
• S. Aleksanian, B. Khorsand, R. Schmidt, J. K. Oh.* Rapidly thiol-responsive degradable block copolymer nanocarriers with facile bioconjugation. Polym. Chem. 2012, 3, 2138-2147.
• B. Khorsand, A. Cunningham, Q. Zhang, J. K. Oh.* Biodegradable block copolymer micelles with thiol-responsive sheddable coronas. Biomacromolecules 2011, 12, 3819-3825.

Thrust II. MDBC/hybrids

Polymers possessing multiple anchoring groups capable of multiple binding interactions with metal and solid surfaces have been designed as effective multidentate ligands. Compared to oligomers and polymers having one or two anchoring groups (mono- and bidentates), the multidentate polymeric ligands exhibit stronger binding isotherms due to more favourable conformational arrangements of multiple anchoring groups tethered from long polymeric chains onto USNP surfaces. We develop the multidentate block copolymers (MDBCs) consist of one block possessing pendant multidentate anchoring groups strongly bound to surfaces, allowing for the fabrication of aqueous colloidal nanostructures (particles) with single ligand layers. The other tunable block varies with components that can promote compatibility with end-use applications. As such, MDBC stabilization is a versatile strategy in that surfaces can be easily tuned via copolymerization, as well as conveniently functionalized with (bio)molecules during the polymerization.

Selected publications

• P. Li, P. Chevallier, P. Ramrup, D. Biswas, D. Vuckovich, M.-A. Fortin, J. K. Oh.* Mussel-inspired multidentate block copolymer to stabilize ultrasmall superparamagnetic Fe₃O₄ for magnetic resonance imaging contrast enhancement and excellent colloidal stability. Chemisty of Materials 2015, 27, 7100-7109
• N. Chan, P. Li, J. K. Oh.* Chain length effect of multidentate block copolymer strategy to stabilize ultrasmall Fe₃O₄ nanoparticles. ChemPlusChem2014, 79, 1342-1351
• N. Chan, Laprise-Pelletier, A. Bianchi, M.-A. Fortin, J. K. Oh.* Multidentate block copolymer stabilized superparamagnetic iron oxide nanoparticles with enhanced stability for magnetic resonance imaging. Biomacromolecules 2014, 15, 2146-2156.
• N. Chan, J. K. Oh.* Functional amphiphilic oligo(ethylene oxide) methacrylate based block copolymers: synthesis by ARGET ATRP and aqueous micellization. Polym. Int. 2014, 63, 858-867.

Thrust III. High-performance industrial materials

Thiol-ene crosslinked materials. We explore thiol-ene click radical reaction to develop photo-induced crosslinked materials based on multifunctional methacrylate copolymer polyenes and polythiols, in collaboration with industries. Our approach possess a number of features; they include possibility of a broad selection of methacrylate monomers to modulate thermal and mechanical properties of crosslinked networks, easy control of crosslinking densities by varying the number of pendant SH or enes, and balance of rigidity/flexibility of crosslinked materials.

Self-healable materials. Inspired by nature, self-healing or self-repairing is a desired property in the design and development of high performance polymeric materials in a broad range of applications, such as surface coatings, tissue engineering, and sensors. Such increasing attention to the development of novel self-healable materials is attributed to their built-in ability to repair physical damages, effectively preventing catastrophic failure and extending the materials lifetime. The physical damages at micro- and mesoscale to be healed include facture due to mechanical deformation, chemical corrosion, and degradation by irradiation. We have developed effective methods to develop intrinsic self-healable materials with no aids of extra healing agents, but occurring at room temperature.

Selected publications

• S. Y. An, D. Arunbabu, S. M. Noh, Y. K. Song, J. K. Oh.* Recent strategies to develop self-healable crosslinked networks (review). Chem. Commun. 2015, 51, 13058-13070.
• S. Y. An, J. K. Oh.* Dual sulfide-disulfide crosslinked networks with rapid and room temperature self-healability. Macromol. Rapid Commun. 2015, 36, 1255-1260.
• Intrinsic self-healable polymethacrylates with reversible cross-links. J. K. Oh, S. Y. An. Provisional Patent Application (2014).
• S. Y. An, J. W. Hwang, K. N. Kim, H. W. Jung, S.M. Noh, J. K. Oh.* Multifunctional linear methacrylate copolymer polyenes having pendant vinyl groups: synthesis and photo-induced thiol-ene crosslinking polyaddition. J. Polym. Sci. Part A 2014, 52, 3713-3721.
• Q. Zhang,^# J. W. Hwang, K. N. Kim, H. W. Jung, S. M. Noh,* J. K. Oh.* New photo-induced thiol-ene crosslinked films based on linear methacrylate copolymer polythiols. J. Polym. Sci. Part A 2013, 51, 2860-2868.