Chemical and Biomolecular Engineering - Research Publications
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ItemFabrication of Chiral Stationary Phases via Continuous Assembly of Polymers for Resolution of Enantiomers by Liquid Chromatography(WILEY-V C H VERLAG GMBH, 2014-11)Precise stereochemical determination of chiral molecules is highly important, especially in the pharmaceutical industry where one enantiomer may have a therapeutic effect while the other has detrimental effects. Herein, the continuous assembly of polymers (CAP) mediated via ring‐opening metathesis polymerization (ROMP) is used to fabricate immobilized‐type chiral stationary phases (CSPs) – as cross‐linked thin films on solid supports – for enantiomeric separation. Optically active polysaccharides (chitosan and amylose) with aromatic substituents were pre‐functionalized with pendent norbornene groups and subsequently employed as macrocross‐linkers in the CAPROMP process, building cross‐linked films from initiator‐functionalized mesoporous silica particles. The immobilized cross‐linked films on mesoporous silica particles can act as CSPs. Therefore, the chiral recognition abilities of the CSPs were explored by liquid chromatography (LC). It was found that CSPs with higher amount of polysaccharide cross‐linked films – made from multiple CAP reactions – have better chiral separation capabilities. This work demonstrates the versatility of the CAP approach to fabricate CSPs to tailor specific separation needs.
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ItemLow-Fouling, Biospecific Films Prepared by the Continuous Assembly of Polymers(AMER CHEMICAL SOC, 2013-08)We report that the continuous assembly of polymers (CAP) approach, mediated by ring-opening metathesis polymerization (ROMP), is a facile and versatile technology to prepare engineered nanocoatings for various biomedical applications. Low-fouling coatings on particles were obtained by the formation of multicompositional, layered films via simple and efficient tandem CAP(ROMP) processes that are analogous to chain extension reactions. In addition, the CAP(ROMP) approach allows for the efficient postfunctionalization of the CAP films with bioactive moieties via cross-metathesis reactions between the surface-immobilized catalysts and symmetrical alkene derivatives. The combined features of the CAP(ROMP) approach (i.e., versatile polymer selection and facile functionalization) allow for the fabrication and surface modification of various types of polymer films, including those with intrinsic protein-repellent properties and selective protein recognition capabilities. This study highlights the various types of advanced coatings and materials that the CAP approach can be used to generate, which may be useful for biomedical applications.
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ItemAssembly of Free-Standing Polypeptide Films via the Synergistic Combination of Hyperbranched Macroinitiators, the Grafting-From Approach, and Cross-Chain Termination(WILEY-V C H VERLAG GMBH, 2013-09-06)Cross-linked polypeptide-based films are fabricated via a novel and robust method employing surface-initiated ring opening polymerization of α-amino acid N-carboxyanhydrides (NCA-ROP). The judicious combination of amine-based hyperbranched macroinitiators and benzyl ester-protected NCA derivatives promotes network formation by cross-chain terminations, which allows the formation of stable cross-linked peptide-based capsules in a one-pot system.
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ItemFabrication of ultra-thin polyrotaxane-based films via solid-state continuous assembly of polymers(ROYAL SOC CHEMISTRY, 2015)Surface-confined ultra-thin polyrotaxane (PRX)-based films with tunable composition, surface topology and swelling characteristics were prepared by solid-state continuous assembly of polymers (ssCAP). The PRX-based films supported cell attachment, and their degradation in biological media could be tuned. This study provides a versatile nano-coating technology with potential applications in biomedicine, including tissue engineering and medical devices.
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Item(Super)hydrophobic and Multilayered Amphiphilic Films Prepared by Continuous Assembly of Polymers(WILEY-V C H VERLAG GMBH, 2013-11-06)Abstract The continuous assembly of polymers (CAP) is used to fabricate tailored nanocoatings on a wide variety of substrates. Ring‐opening metathesis polymerization (ROMP) is used to mediate the CAP process (CAPROMP) to assemble specifically designed macromolecules into nanoengineered crosslinked films. Different films composed of single or multiple macromolecules are used to tune the surface wetting characteristics on various planar substrates, including porous substrates such as filter paper and cotton, and non‐porous subtrates such as aluminium foil and glass. By judicious selection of the macromolecules, these substrates, which are hydrophilic in nature, can be rendered (super)hydrophobic. The robustness of the ROMP catalysts and the reinitiation ability of the CAPROMP approach allow the production of layered multicomponent amphiphilic films with on‐demand switchable wettability. Such functional nanocoatings can be potentially applied as self‐cleaning surfaces, as waterproof woven fabrics, and for the next generation of microelectronic devices.
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ItemAssembly of Nanostructured Films with Hydrophobic Subcompartments via Continuous Assembly of Polymers(AMER CHEMICAL SOC, 2013-10-08)
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ItemFunctional and Well-Defined β-Sheet-Assembled Porous Spherical Shells by Surface-Guided Peptide Formation(Wiley-VCH Verlag, 2015-06-01)Polypeptides have attracted widespread attention as building blocks for complex materials due to their ability to form higher‐ordered structures such as β‐sheets. However, the ability to precisely control the formation of well‐defined β‐sheet‐assembled materials remains challenging as β‐sheet formation tends to lead to ill‐defined and unprocessable aggregates. This work reports a simple, rapid, and robust strategy to form well‐defined peptide β‐sheet‐assembled shells (i.e., hollow spheres) by employing surface‐initiated N‐carboxyanhydride ring‐opening polymerization under a highly efficient surface‐driven approach. The concept is demonstrated by the preparation of enzyme‐degradable rigid shell architectures composed of H‐bonded poly(L‐valine) (PVal) grafts with porous and sponge‐like surface morphology. The porous PVal‐shells exhibit a remarkable and unprecedented ability to non‐covalently entrap metal nanoparticles, proteins, drug molecules, and biorelevant polymers, which could potentially lead to a diverse range of biodegradable and functional platforms for applications ranging from therapeutic delivery to organic catalysis.