Chemical and Biomolecular Engineering - Research Publications
Permanent URI for this collection
Search Results
1 - 10 of 11
-
ItemSite-Selective Coordination Assembly of Dynamic Metal-Phenolic Networks(WILEY-V C H VERLAG GMBH, 2022-08-22)Coordination states of metal-organic materials are known to dictate their physicochemical properties and applications in various fields. However, understanding and controlling coordination sites in metal-organic systems is challenging. Herein, we report the synthesis of site-selective coordinated metal-phenolic networks (MPNs) using flavonoids as coordination modulators. The site-selective coordination was systematically investigated experimentally and computationally using ligands with one, two, and multiple different coordination sites. Tuning the multimodal Fe coordination with catechol, carbonyl, and hydroxyl groups within the MPNs enabled the facile engineering of diverse physicochemical properties including size, selective permeability (20-2000 kDa), and pH-dependent degradability. This study expands our understanding of metal-phenolic chemistry and provides new routes for the rational design of structurally tailorable coordination-based materials.
-
ItemAssembly of Bioactive Nanoparticles via Metal-Phenolic Complexation(Wiley, 2022)The integration of bioactive materials (e.g., proteins and genes) into nanoparticles holds promise in fields ranging from catalysis to biomedicine. However, it is challenging to develop a simple and broadly applicable nanoparticle platform that can readily incorporate distinct biomacromolecules without affecting their intrinsic activity. Herein, a metal-phenolic assembly approach is presented whereby diverse functional nanoparticles can be readily assembled in water by combining various synthetic and natural building blocks, including poly(ethylene glycol), phenolic ligands, metal ions, and bioactive macromolecules. The assembly process is primarily mediated by metal-phenolic complexes through coordination and hydrophobic interactions, which yields uniform and spherical nanoparticles (mostly <200 nm), while preserving the function of the incorporated biomacromolecules (siRNA and five different proteins used). The functionality of the assembled nanoparticles is demonstrated through cancer cell apoptosis, RNA degradation, catalysis, and gene downregulation studies. Furthermore, the resulting nanoparticles can be used as building blocks for the secondary engineering of superstructures via templating and cross-linking with metal ions. The bioactivity and versatility of the platform can potentially be used for the streamlined and rational design of future bioactive materials.
-
ItemMacromolecular Engineering of Thermoresponsive Metal-Phenolic Networks(AMER CHEMICAL SOC, 2022-01-01)Dynamic nanostructured materials that can react to physical and chemical stimuli have attracted interest in the biomedical and materials science fields. Metal-phenolic networks (MPNs) represent a modular class of such materials: these networks form via coordination of phenolic molecules with metal ions and can be used for surface and particle engineering. To broaden the range of accessible MPN properties, we report the fabrication of thermoresponsive MPN capsules using FeIII ions and the thermoresponsive phenolic building block biscatechol-functionalized poly(N-isopropylacrylamide) (biscatechol-PNIPAM). The MPN capsules exhibited reversible changes in capsule size and shell thickness in response to temperature changes. The temperature-induced capsule size changes were influenced by the chain length of biscatechol-PNIPAM and catechol-to-FeIII ion molar ratio. The metal ion type also influenced the capsule size changes, allowing tuning of the MPN capsule mechanical properties. AlIII-based capsules, having a lower stiffness value (10.7 mN m-1), showed a larger temperature-induced size contraction (∼63%) than TbIII-based capsules, which exhibit a higher stiffness value (52.6 mN m-1) and minimal size reduction (<1%). The permeability of the MPN capsules was controlled by changing the temperature (25-50 °C)─a reduced permeability was obtained as the temperature was increased above the lower critical solution temperature of biscatechol-PNIPAM. This temperature-dependent permeability behavior was exploited to encapsulate and release model cargo (500 kDa fluorescein isothiocyanate-tagged dextran) from the capsules; approximately 70% was released over 90 min at 25 °C. This approach provides a synthetic strategy for developing dynamic and thermoresponsive-tunable MPN systems for potential applications in biological science and biotechnology.
-
ItemLuminescent Metal-Phenolic Networks for Multicolor Particle Labeling(WILEY-V C H VERLAG GMBH, 2021-11-15)The development of fluorescence labeling techniques has attracted widespread interest in various fields, including biomedical science as it can facilitate high-resolution imaging and the spatiotemporal understanding of various biological processes. We report a supramolecular fluorescence labeling strategy using luminescent metal-phenolic networks (MPNs) constructed from metal ions, phenolic ligands, and common and commercially available dyes. The rapid labeling process (<5 min) produces ultrathin coatings (≈10 nm) on diverse particles (e.g., organic, inorganic, and biological entities) with customized luminescence (e.g., red, blue, multichromatic, and white light) simply through the selection of fluorophores. The fluorescent coatings are stable at pH values from 1 to 8 and in complex biological media owing to the dominant π interactions between the dyes and MPNs. These coatings exhibit negligible cytotoxicity and their strong fluorescence is retained even when internalized into intracellular compartments. This strategy is expected to provide a versatile approach for fluorescence labeling with potential in diverse fields across the physical and life sciences.
-
ItemSynthesis of Customizable Macromolecular Conjugates as Building Blocks for Engineering Metal–Phenolic Network Capsules with Tailorable Properties(American Chemical Society (ACS), 2021)Metal–phenolic networks (MPNs), formed through coordination bonding between phenolic molecules and metal ions, are a promising class of materials for engineering particle systems for diverse applications. However, the properties of such MPNs are inherently restricted due to the finite properties of naturally occurring phenolic molecules. Herein, we report a simple and robust approach to incorporate phenolic moieties into polymers, thereby providing customizable phenolic ligand building blocks that can be used to assemble capsules with a range of tailorable properties. The phenolic ligand building blocks were synthesized via carbonic anhydride coupling to terminal amines, a conjugation approach typically used for peptide coupling but applied herein for functionalizing polymers. The chemistry enabled optimized end-group purity, thus affording a robust and efficient strategy to generate a library of macromolecular poly(ethylene glycol) (PEG) catechol building blocks with different architectures (i.e., 2-, 4-, and 8-arm) and molecular weights (from 2.5 to 20 kDa). The resulting phenolic building blocks were applied to fabricate capsules with shell thickness, permeability, and cell association properties that were controlled via the variation of the macromolecular catechol architecture and molecular weight. Specifically, the shell thickness was varied more than 19-fold (i.e., between ∼9 and 169 nm) by judicious selection of the polymer molecular weight, arm number, and template. Similarly, the permeability of the resulting MPN capsules to 500 kDa dextran was tuned from >90 to <5% by varying the number of arms in the polymer structure while maintaining a constant PEG Mn-to-catechol group ratio. Furthermore, the cell association was reduced by a factor of 2.5 by employing 20 kDa 8-arm PEG instead of 2.5 kDa 2-arm PEG during film assembly. These results demonstrate that the applied macromolecular conjugation approach can be used to customize particle properties, potentially facilitating applications in therapeutic delivery, imaging, separations, and catalysis.
-
ItemExploiting Supramolecular Dynamics in Metal-Phenolic Networks to Generate Metal-Oxide and Metal-Carbon Networks(WILEY-V C H VERLAG GMBH, 2021-06-21)Supramolecular complexation is a powerful strategy for engineering materials in bulk and at interfaces. Metal-phenolic networks (MPNs), which are assembled through supramolecular complexes, have emerged as suitable candidates for surface and particle engineering owing to their diverse properties. Herein, we examine the supramolecular dynamics of MPNs during thermal transformation processes. Changes in the local supramolecular network including enlarged pores, ordered aromatic packing, and metal relocation arise from thermal treatment in air or an inert atmosphere, enabling the engineering of metal-oxide networks (MONs) and metal-carbon networks, respectively. Furthermore, by integrating photo-responsive motifs (i.e., TiO2 ) and silanization, the MONs are endowed with reversible superhydrophobic (>150°) and superhydrophilic (≈0°) properties. By highlighting the thermodynamics of MPNs and their transformation into diverse materials, this work offers a versatile pathway for advanced materials engineering.
-
ItemMetal–Phenolic Networks as Tunable Buffering Systems(American Chemical Society (ACS), 2021)The buffering effects displayed by pH‐responsive polymers have recently gained attention in diverse fields such as nanomedicine and water treatment. However, creating libraries of modular and versatile polymers that can be readily integrated within existing materials remains challenging, hence restricting applications inspired by their buffering capacity. Herein, we propose the use of metal–phenolic networks (MPNs) as tunable buffering systems and through mechanistic studies show that their buffering effects are driven by pH‐responsive, multivalent metal–phenolic coordination. Owing to such supramolecular interactions, MPNs exhibit ~2‐fold and 3‐fold higher buffering capacity than polyelectrolyte complexes and commercial buffer solutions, respectively. We demonstrate that the MPN buffering effects are retained after deposition onto solid supports, thereby allowing stabilization of aqueous environmental pH for 1 week. Moreover, by using different metals and ligands for the films, the endosomal escape capabilities of coated nanoparticles can be tuned, where higher buffering capacity leads to greater endosomal escape. This study forms a fundamental basis for developing future metal–organic buffering materials.
-
ItemParticle engineering enabled by polyphenol-mediated supramolecular networks.(Nature Research, 2020-09-23)We report a facile strategy for engineering diverse particles based on the supramolecular assembly of natural polyphenols and a self-polymerizable aromatic dithiol. In aqueous conditions, uniform and size-tunable supramolecular particles are assembled through π-π interactions as mediated by polyphenols. Owing to the high binding affinity of phenolic motifs present at the surface, these particles allow for the subsequent deposition of various materials (i.e., organic, inorganic, and hybrid components), producing a variety of monodisperse functional particles. Moreover, the solvent-dependent disassembly of the supramolecular networks enables their removal, generating a wide range of corresponding hollow structures including capsules and yolk-shell structures. The versatility of these supramolecular networks, combined with their negligible cytotoxicity provides a pathway for the rational design of a range of particle systems (including core-shell, hollow, and yolk-shell) with potential in biomedical and environmental applications.
-
ItemProgrammable Permeability of Metal–Phenolic Network Microcapsules(American Chemical Society (ACS), 2020-08-25)Developing materials with programmable permeability for cargo encapsulation and release is challenging but important in a number of fields including drug delivery and sensing. Metal–phenolic networks (MPNs) are an emerging class of hybrid coordination materials with pH-responsiveness and modularity that can be engineered into functional thin films for diverse applications. Herein, we engineer MPN-based microcapsules with a dynamic gating mechanism by adjusting the intermolecular interactions in the capsules. Altering the choice of building blocks and precursor ratio provides an intrinsic and modular means of tailoring capsule size and permeability. Alternatively, regulating the pH of the environment, and thereby the protonation states of MPNs, extrinsically enables capsules to switch between highly permeable (>90% of capsules permeable at pH 9) and near-impermeable (<20% at pH 3) states. These findings provide insights into the dynamic nature of MPNs and offer a route to engineer smart delivery systems and selective gating materials.
-
ItemEngineering of Nebulized Metal-Phenolic Capsules for Controlled Pulmonary Deposition(John Wiley & Sons, 2020-03-18)Particle-based pulmonary delivery has great potential for delivering inhalable therapeutics for local or systemic applications. The design of particles with enhanced aerodynamic properties can improve lung distribution and deposition, and hence the efficacy of encapsulated inhaled drugs. This study describes the nanoengineering and nebulization of metal–phenolic capsules as pulmonary carriers of small molecule drugs and macromolecular drugs in lung cell lines, a human lung model, and mice. Tuning the aerodynamic diameter by increasing the capsule shell thickness (from ≈100 to 200 nm in increments of ≈50 nm) through repeated film deposition on a sacrificial template allows precise control of capsule deposition in a human lung model, corresponding to a shift from the alveolar region to the bronchi as aerodynamic diameter increases. The capsules are biocompatible and biodegradable, as assessed following intratracheal administration in mice, showing >85% of the capsules in the lung after 20 h, but <4% remaining after 30 days without causing lung inflammation or toxicity. Single-cell analysis from lung digests using mass cytometry shows association primarily with alveolar macrophages, with >90% of capsules remaining nonassociated with cells. The amenability to nebulization, capacity for loading, tunable aerodynamic properties, high biocompatibility, and biodegradability make these capsules attractive for controlled pulmonary delivery.