School of Chemistry - Research Publications

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    The Future of Layer-by-Layer Assembly: A Tribute to ACS Nano Associate Editor Helmuth Mohwald
    Zhao, S ; Caruso, F ; Daehne, L ; Decher, G ; De Geest, BG ; Fan, J ; Feliu, N ; Gogotsi, Y ; Hammond, PT ; Hersam, MC ; Khademhosseini, A ; Kotov, N ; Leporatti, S ; Li, Y ; Lisdat, F ; Liz-Marzan, LM ; Moya, S ; Mulvaney, P ; Rogach, AL ; Roy, S ; Shchukin, DG ; Skirtach, AG ; Stevens, MM ; Sukhorukov, GB ; Weiss, PS ; Yue, Z ; Zhu, D ; Parak, WJ (AMER CHEMICAL SOC, 2019-06)
    Layer-by-layer (LbL) assembly is a widely used tool for engineering materials and coatings. In this Perspective, dedicated to the memory of ACS Nano associate editor Prof. Dr. Helmuth Möhwald, we discuss the developments and applications that are to come in LbL assembly, focusing on coatings, bulk materials, membranes, nanocomposites, and delivery vehicles.
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    Modulating Targeting of Poly(ethylene glycol) Particles to Tumor Cells Using Bispecific Antibodies
    Cui, J ; Ju, Y ; Houston, ZH ; Class, JJ ; Fletcher, NL ; Alcantara, S ; Dai, Q ; Howard, CB ; Mahler, SM ; Wheatley, AK ; De Rose, R ; Brannon, PT ; Paterson, BM ; Donnelly, PS ; Thurecht, K ; Caruso, F ; Kent, SJ (WILEY, 2019-05)
    Low-fouling or "stealth" particles composed of poly(ethylene glycol) (PEG) display a striking ability to evade phagocytic cell uptake. However, functionalizing them for specific targeting is challenging. To address this challenge, stealth PEG particles prepared by a mesoporous silica templating method are functionalized with bispecific antibodies (BsAbs) to obtain PEG-BsAb particles via a one-step binding strategy for cell and tumor targeting. The dual specificity of the BsAbs-one arm binds to the PEG particles while the other targets a cell antigen (epidermal growth factor receptor, EGFR)-is exploited to modulate the number of targeting ligands per particle. Increasing the BsAb incubation concentration increases the amount of BsAb tethered to the PEG particles and enhances targeting and internalization into breast cancer cells overexpressing EGFR. The degree of BsAb functionalization does not significantly reduce the stealth properties of the PEG particles ex vivo, as assessed by their interactions with primary human blood granulocytes and monocytes. Although increasing the BsAb amount on PEG particles does not lead to the expected improvement in tumor accumulation in vivo, BsAb functionalization facilitates tumor cell uptake of PEG particles. This work highlights strategies to balance evading nonspecific clearance pathways, while improving tumor targeting and accumulation.
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    Continuous assembly of polymers via solid phase reactions
    Nam, E ; Kim, J ; Guntari, SN ; Seyler, H ; Fu, Q ; Wong, EHH ; Blencowe, A ; Jones, DJ ; Caruso, F ; Qiao, GG (ROYAL SOC CHEMISTRY, 2014-09)

    The formation of cross-linked polymer films, with tunable thickness, proceeds directionally from the substrate surface by controlled polymerization in the solid state.

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    One-Step Assembly of Coordination Complexes for Versatile Film and Particle Engineering
    Ejima, H ; Richardson, JJ ; Liang, K ; Best, JP ; van Koeverden, MP ; Such, GK ; Cui, J ; Caruso, F (AMER ASSOC ADVANCEMENT SCIENCE, 2013-07-12)
    The development of facile and versatile strategies for thin-film and particle engineering is of immense scientific interest. However, few methods can conformally coat substrates of different composition, size, shape, and structure. We report the one-step coating of various interfaces using coordination complexes of natural polyphenols and Fe(III) ions. Film formation is initiated by the adsorption of the polyphenol and directed by pH-dependent, multivalent coordination bonding. Aqueous deposition is performed on a range of planar as well as inorganic, organic, and biological particle templates, demonstrating an extremely rapid technique for producing structurally diverse, thin films and capsules that can disassemble. The ease, low cost, and scalability of the assembly process, combined with pH responsiveness and negligible cytotoxicity, makes these films potential candidates for biomedical and environmental applications.
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    Stiffness-mediated adhesion of cervical cancer cells to soft hydrogel films
    Best, JP ; Javed, S ; Richardson, JJ ; Cho, KL ; Kamphuis, MMJ ; Caruso, F (ROYAL SOC CHEMISTRY, 2013)
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    Design of Degradable Click Delivery Systems
    Such, GK ; Gunawan, ST ; Liang, K ; Caruso, F (WILEY-V C H VERLAG GMBH, 2013-06-13)
    Click chemistry has had a significant impact in the field of materials science over the last 10 years, as it has enabled the design of new hybrid building blocks, leading to multifunctional and responsive materials. One key application for such materials is in the biomedical field, such as gene or drug delivery. However, to meet the functional requirements of such applications, tailored degradability of these materials under biological conditions is critical. There has been an increasing interest in combining click chemistry techniques with a range of degradable or responsive building blocks as well as investigating new or milder chemistries to design click delivery systems that are capable of physiologically relevant degradation. This Feature Article will cover some of the different approaches to synthesize degradable click delivery systems and their investigation for therapeutic release.
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    Standardizing Nanomaterials
    Mulvaney, P ; Parak, WJ ; Caruso, F ; Weiss, PS (AMER CHEMICAL SOC, 2016-11)
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    Immobilization and Intracellular Delivery of an Anticancer Drug Using Mussel-Inspired Polydopamine Capsules
    Cui, J ; Yan, Y ; Such, GK ; Liang, K ; Ochs, CJ ; Postma, A ; Caruso, F (AMER CHEMICAL SOC, 2012-08)
    We report a facile approach to immobilize pH-cleavable polymer-drug conjugates in mussel-inspired polydopamine (PDA) capsules for intracellular drug delivery. Our design takes advantage of the facile PDA coating to form capsules, the chemical reactivity of PDA films, and the acid-labile groups in polymer side chains for sustained pH-induced drug release. The anticancer drug doxorubicin (Dox) was conjugated to thiolated poly(methacrylic acid) (PMA(SH)) with a pH-cleavable hydrazone bond, and then immobilized in PDA capsules via robust thiol-catechol reactions between the polymer-drug conjugate and capsule walls. The loaded Dox showed limited release at physiological pH but significant release (over 85%) at endosomal/lysosomal pH. Cell viability assays showed that Dox-loaded PDA capsules enhanced the efficacy of eradicating HeLa cancer cells compared with free drug under the same assay conditions. The reported method provides a new platform for the application of stimuli-responsive PDA capsules as drug delivery systems.
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    Biodegradable Click Capsules with Engineered Drug-Loaded Multilayers
    Ochs, CJ ; Such, GK ; Yan, Y ; van Koeverden, MP ; Caruso, F (AMER CHEMICAL SOC, 2010-03)
    We report the modular assembly of a polymer-drug conjugate into covalently stabilized, responsive, biodegradable, and drug-loaded capsules with control over drug dose and position in the multilayer film. The cancer therapeutic, doxorubicin hydrochloride (DOX), was conjugated to alkyne-functionalized poly(l-glutamic acid) (PGA(Alk)) via amide bond formation. PGA(Alk) and PGA(Alk+DOX) were assembled via hydrogen bonding with poly(N-vinyl pyrrolidone) (PVPON) on planar and colloidal silica templates. The films were subsequently covalently stabilized using diazide cross-linkers, and PVPON was released from the multilayers by altering the solution pH to disrupt hydrogen bonding. After removal of the sacrificial template, single-component PGA(Alk) capsules were obtained and analyzed by optical microscopy, transmission electron microscopy, and atomic force microscopy. The PGA(Alk) capsules were stable in the pH range between 2 and 11 and exhibited reversible swelling/shrinking behavior. PGA(Alk+DOX) was assembled to form drug-loaded polymer capsules with control over drug dose and position in the multilayer system (e.g., DOX in every layer or exclusively in layer 3). The drug-loaded capsules could be degraded enzymatically, resulting in the sustained release of active DOX over approximately 2 h. Cellular uptake studies demonstrate that the viability of cells incubated with DOX-loaded PGA(Alk) capsules significantly decreased. The general applicability of this modular approach, in terms of incorporation of polymer-drug conjugates in other click multilayer systems, was also demonstrated. Biodegradable click capsules with drug-loaded multilayers are promising candidates as carrier systems for biomedical applications.
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    Photoinitiated Alkyne-Azide Click and Radical Cross-Linking Reactions for the Patterning of PEG Hydrogels
    Chen, RT ; Marchesan, S ; Evans, RA ; Styan, KE ; Such, GK ; Postma, A ; McLean, KM ; Muir, BW ; Caruso, F (AMER CHEMICAL SOC, 2012-03)
    The photolithographical patterning of hydrogels based solely on the surface immobilization and cross-linking of alkyne-functionalized poly(ethylene glycol) (PEG-tetraalkyne) is described. Photogenerated radicals as well as UV absorption by a copper chelating ligand result in the photochemical redox reduction of Cu(II) to Cu(I). This catalyzes the alkyne-azide click reaction to graft the hydrogels onto an azide-functionalized plasma polymer (N(3)PP) film. The photogenerated radicals were also able to abstract hydrogen atoms from PEG-tetraalkyne to form poly(α-alkoxy) radicals. These radicals can initiate cross-linking by addition to the alkynes and intermolecular recombination to form the PEG hydrogels. Spatially controlling the two photoinitiated reactions by UV exposure through a photomask leads to surface patterned hydrogels, with thicknesses that were tunable from tens to several hundreds of nanometers. The patterned PEG hydrogels (ca. 60 μm wide lines) were capable of resisting the attachment of L929 mouse fibroblast cells, resulting in surfaces with spatially controlled cell attachment. The patterned hydrogel surface also demonstrated spatially resolved chemical functionality, as postsynthetic modification of the hydrogels was successfully carried out with azide-functionalized fluorescent dyes via subsequent alkyne-azide click reactions.