Chemical and Biomolecular Engineering - Research Publications
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ItemThe use of carbonic anhydrase to accelerate carbon dioxide capture processes(WILEY, 2015-01)The chemical absorption of CO2 into a monoethanolamine solvent is currently the most widely accepted commercial approach to carbon dioxide capture. However, the subsequent desorption of CO2 from the solvents is extremely energy intensive. Alternative solvents are more energy efficient, but their slow reaction kinetics in the CO2 absorption step limits application. The use of a carbonic anhydrase (CA) enzyme as a reaction promoter can potentially overcome this obstacle. Native, engineered and artificial CA enzymes have been investigated for this application. Immobilization of the enzyme within the gas absorber or in a membrane format can increase enzyme stability and avoid thermal denaturation in the stripper. However, immobilization is only effective if the mass transfer of carbon dioxide through the liquid phase to reach the immobilization substrate does not become rate controlling. Further research should also consider the process economics of large-scale enzyme production and the long-term performance of the enzyme under real flue gas conditions.
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ItemSynthesis of Chemically Asymmetric Silica Nanobottles and Their Application for Cargo Loading and as Nanoreactors and Nanomotors(Wiley, 2016-11-14)Abstract We report the synthesis of chemically asymmetric silica nanobottles (NBs) with a hydrophobic exterior surface (capped with 3‐chloropropyl groups) and a hydrophilic interior surface for spatially selective cargo loading, and for application as nanoreactors and nanomotors. The silica NBs, which have a “flask bottle” shape with an average diameter of 350 nm and an opening of ca. 100 nm, are prepared by anisotropic sol–gel growth in a water/n‐pentanol emulsion. Due to their chemically asymmetric properties, nanoparticles (NPs) with hydrophilic or hydrophobic surface properties can be selectively loaded inside the NBs or on the outside of the NBs, respectively. A high‐performance nanomotor is constructed by selectively loading catalytically active hydrophilic Pt NPs inside the NBs. It is also demonstrated that these NBs can be used as vessels for various reactions, such as the in situ synthesis of Au NPs, and using Au NP‐loaded NBs as nanoreactors for catalytic reactions.
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ItemSynthesis of Discrete Alkyl‐Silica Hybrid Nanowires and Their Assembly into Nanostructured Superhydrophobic Membranes(Wiley, 2016-07-11)Abstract We report the synthesis of highly flexible and mechanically robust hybrid silica nanowires (NWs) which can be used as novel building blocks to construct superhydrophobic functional materials with three‐dimensional macroporous networks. The hybrid silica NWs, with an average diameter of 80 nm and tunable length of up to 12 μm, are prepared by anisotropic deposition of the hydrolyzed tetraethylorthosilicate in water/n‐pentanol emulsions. A mechanistic investigation reveals that the trimethoxy(octadecyl)silane introduced to the water‐oil interface in the synthesis plays key roles in stabilizing the water droplets to sub‐100 nm and also growing a layer of octadecyl groups on the NW surface. This work opens a solution‐based route for the one‐pot preparation of monodisperse, hydrophobic silica NWs and represents an important step toward the bottom‐up construction of 3D superhydrophobic materials and macroporous membranes.
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ItemOxidation‐Mediated Kinetic Strategies for Engineering Metal–Phenolic Networks(Wiley, 2019-09-02)Abstract The tunable growth of metal–organic materials has implications for engineering particles and surfaces for diverse applications. Specifically, controlling the self‐assembly of metal–phenolic networks (MPNs), an emerging class of metal–organic materials, is challenging, as previous studies suggest that growth often terminates through kinetic trapping. Herein, kinetic strategies were used to temporally and spatially control MPN growth by promoting self‐correction of the coordinating building blocks through oxidation‐mediated MPN assembly. The formation and growth mechanisms were investigated and used to engineer films with microporous structures and continuous gradients. Moreover, reactive oxygen species generated by ultrasonication expedite oxidation and result in faster (ca. 30 times) film growth than that achieved by other MPN assembly methods. This study expands our understanding of metal–phenolic chemistry towards engineering metal–phenolic materials for various applications.
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ItemPhenolische Bausteine für die Assemblierung von Funktionsmaterialien(Wiley, 2019-02-11)Abstract Phenolische Materialien sind seit langem für ihre Verwendung in Farbtinten, in Holzbeschichtungen und zur Ledergerbung bekannt. In letzter Zeit ist jedoch ein wachsendes Interesse an der Entwicklung moderner Werkstoffe aus phenolischen Bausteinen zu verzeichnen. Die intrinsischen Eigenschaften von phenolischen Verbindungen, wie Metallchelat‐Bildung, Wasserstoffbrücken, pH‐Ansprechverhalten, Redoxpotentiale, Radikalfänger, Polymerisation und Lichtabsorption, haben sie zu einer eigenständigen Klasse von Strukturelementen für die Synthese von funktionellen Materialien gemacht. Aus Phenolverbindungen hergestellte Materialien behalten viele ihrer nützlichen Eigenschaften, oft mit synergistischen Effekten bei Anwendungen, die von der Katalyse bis zur Biomedizin reichen. Dieser Aufsatz gibt einen Überblick über die verschiedenen funktionellen Materialien, die aus natürlichen und synthetischen phenolischen Bausteinen hergestellt werden können, und über ihre Anwendungen.
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ItemNo Preview AvailableAn Electrifying Choice for the 2019 Chemistry Nobel Prize: Goodenough, Whittingham, and Yoshino(AMER CHEMICAL SOC, 2019-11-12)As editors of a materials chemistry journal, we are thrilled at the awarding of the 2019 Nobel Prize in Chemistry to John B. Goodenough, M. Stanley Whittingham, and Akira Yoshino, for their contributions that have led to the modern lithium ion battery (Figure 1). As the Nobel Prize Committee states succinctly, “They created a rechargeable world.”(1) The commercial and societal rewards of experimental research typically require decades to reach fruition, and lithium ion batteries were no different, with crucial leads dating back to the 1960s, and even earlier.(2) Materials chemistry journals only emerged 30 years ago with the advent of Chemistry of Materials, the Journal of Materials Chemistry, and Advanced Materials in 1989. Much of the earlier work in battery materials appeared beforehand in electrochemistry, physics, and solid state journals. The key fundamental discovery underpinning the lithium ion battery was the understanding and application of ion intercalation, in this case,(3) lithium ions inserted between the layers in graphite, metal sulfides, and, eventually, oxides that were commercialized. This Nobel Prize was evenly split three ways because, as the Nobel committee correctly observed, the contributions of all three inventors were essential to the success of the commercialization of the lithium ion battery.
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ItemNanoengineering of Poly(ethylene glycol) Particles for Stealth and Targeting(AMER CHEMICAL SOC, 2018-09-18)The assembly of particles composed solely or mainly of poly(ethylene glycol) (PEG) is an emerging area that is gaining increasing interest within bio-nano science. PEG, widely considered to be the "gold standard" among polymers for drug delivery, is providing a platform for exploring fundamental questions and phenomena at the interface between particle engineering and biomedicine. These include the targeting and stealth behaviors of synthetic nanomaterials in biological environments. In this feature article, we discuss recent work in the nanoengineering of PEG particles and explore how they are enabling improved targeting and stealth performance. Specific examples include PEG particles prepared through surface-initiated polymerization, mesoporous silica replication via postinfiltration, and particle assembly through metal-phenolic coordination. This particle class exhibits unique in vivo behavior (e.g., biodistribution and immune cell interactions) and has recently been explored for drug delivery applications.
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ItemRicocheting Droplets Moving on Super-Repellent Surfaces(Wiley Open Access, 2019-09-12)Droplet bouncing on repellent solid surfaces (e.g., the lotus leaf effect) is a common phenomenon that has aroused interest in various fields. However, the scenario of a droplet bouncing off another droplet (either identical or distinct chemical composition) while moving on a solid material (i.e., ricocheting droplets, droplet billiards) is scarcely investigated, despite it having fundamental implications in applications including self‐cleaning, fluid transport, and heat and mass transfer. Here, the dynamics of bouncing collisions between liquid droplets are investigated using a friction‐free platform that ensures ultrahigh locomotion for a wide range of probing liquids. A general prediction on bouncing droplet–droplet contact time is elucidated and bouncing droplet–droplet collision is demonstrated to be an extreme case of droplet bouncing on surfaces. Moreover, the maximum deformation and contact time are highly dependent on the position where the collision occurs (i.e., head‐on or off‐center collisions), which can now be predicted using parameters (i.e., effective velocity, effective diameter) through the concept of an effective interaction region. The results have potential applications in fields ranging from microfluidics to repellent coatings.
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ItemMetal-Phenolic Coatings as a Platform to Trigger Endosomal Escape of Nanoparticles.(American Chemical Society, 2019-10-22)The intracellular delivery of functional nanoparticles (NPs) and the release of therapeutic payloads at a target site are central issues for biomedical applications. However, the endosomal entrapment of NPs typically results in the degradation of active cargo, leading to poor therapeutic outcomes. Current advances to promote the endosomal escape of NPs largely involve the use of polycationic polymers and cell-penetrating peptides (CPPs), which both can suffer from potential toxicity and convoluted synthesis/conjugation processes. Herein, we report the use of metal-phenolic networks (MPNs) as versatile and nontoxic coatings to facilitate the escape of NPs from endo/lysosomal compartments. The MPNs, which were engineered from the polyphenol tannic acid and FeIII or AlIII, enabled the endosomal escape of both inorganic (mesoporous silica) and organic (polystyrene and melamine resin) NPs owing to the "proton-sponge effect" arising from the buffering capacity of MPNs. Postfunctionalization of the MPN-coated NPs with low-fouling polymers did not impair the endosomal escape, indicating the modular and generalizable nature of this approach. We envisage that the ease of fabrication, versatility, low cytotoxicity, and promising endosomal escape performance displayed by the MPN coatings offer opportunities for such coatings to be used for the efficient delivery of cytoplasm-targeted therapeutics using NPs.
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ItemNo Preview AvailableDesigning Particles for Biological Interactions( 2018-07-31)Oral presentation at ACS Publications Symposium - Innovative Materials for a Sustainable World