Chemical and Biomedical Engineering - Research Publications
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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.
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ItemModular Assembly of Host-Guest Metal-Phenolic Networks Using Macrocyclic Building Blocks(Wiley, 2020-01-02)The manipulation of interfacial properties has broad implications for the development of high‐performance coatings. Metal–phenolic networks (MPNs) are an emerging class of responsive, adherent materials. Herein, host–guest chemistry is integrated with MPNs to modulate their surface chemistry and interfacial properties. Macrocyclic cyclodextrins (host) are conjugated to catechol or galloyl groups and subsequently used as components for the assembly of functional MPNs. The assembled cyclodextrin‐based MPNs are highly permeable (even to high molecular weight polymers: 250–500 kDa), yet they specifically and noncovalently interact with various functional guests (including small molecules, polymers, and carbon nanomaterials), allowing for modular and reversible control over interfacial properties. Specifically, by using either hydrophobic or hydrophilic guest molecules, the wettability of the MPNs can be readily tuned between superrepellency (>150°) and superwetting (ca. 0°).
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ItemThe Biomolecular Corona in 2D and Reverse: Patterning Metal–Phenolic Networks on Proteins, Lipids, Nucleic Acids, Polysaccharides, and Fingerprints(Wiley, 2020-01-03)The adsorption of biomolecules onto nanomaterials can alter the performance of the nanomaterials in vitro and in vivo. Recent studies have primarily focused on the protein “corona”, formed upon adsorption of proteins onto nanoparticles in biological fluids, which can change the biological fate of the nanoparticles. Conversely, interactions between nanomaterials and other classes of biomolecules namely, lipids, nucleic acids, and polysaccharides have received less attention despite their important roles in biology. A possible reason is the challenge associated with investigating biomolecule interactions with nanomaterials using current technologies. Herein, a protocol is developed for studying bio–nano interactions by depositing four classes of biomolecules (proteins, lipids, nucleic acids, and polysaccharides) and complex biological media (blood) onto planar substrates, followed by exposure to metal–phenolic network (MPN) complexes. The MPNs preferentially interact with the biomolecule over the inorganic substrate (glass), highlighting that patterned biomolecules can be used to engineer patterned MPNs. Subsequent formation of silver nanoparticles on the MPN films maintains the patterns and endows the films with unique reflectance and fluorescence properties, enabling visualization of latent fingerprints (i.e., invisible residual biomolecule patterns). This study demonstrates the potential complexity of the biomolecule corona as all classes of biomolecules can adsorb onto MPN-based nanomaterials.
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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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ItemTuning the Mechanical Behavior of Metal-Phenolic Networks through Building Block Composition(AMER CHEMICAL SOC, 2019-02-13)Metal-phenolic networks (MPNs) are an emerging class of functional metal-organic materials with a high degree of modularity in terms of the choice of metal ion, phenolic ligand, and assembly method. Although various applications, including drug delivery, imaging, and catalysis, have been studied with MPNs, in the form of films and capsules, the influence of metals and organic building blocks on their mechanical properties is poorly understood. Herein, we demonstrate that the mechanical properties of MPNs can be tuned through choice of the metal ion and/or phenolic ligand. Specifically, the pH of the metal ion solution and/or size of phenolic ligand influence the Young's modulus ( EY) of MPNs (higher pHs and smaller ligands lead to higher EY). This study systematically investigates the roles of both metal ions and ligands on the mechanical properties of metal-organic materials and provides new insight into engineering the mechanical properties of coordination films.
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ItemSpray Assembly of Metal-Phenolic Networks: Formation, Growth, and Applications(AMER CHEMICAL SOC, 2018-10-03)Hybrid conformal coatings, such as metal-phenolic networks (MPNs) that are constructed from the coordination-driven assembly of natural phenolic ligands, are of interest in areas including biomedicine, separations, and energy. To date, most MPN coatings have been prepared by immersing substrates in solutions containing the phenolic ligands and metal ions, which is a suitable method for coating small or flexible objects. In contrast, more industrially relevant methods for coating and patterning large substrates, such as spray assembly, have been explored to a lesser extent toward the fabrication of MPNs, particularly regarding the effect of process variables on MPN growth. Herein, a spray assembly method was used to fabricate MPN coatings with various phenolic building blocks and metal ions and their formation and patterning were explored for different applications. Different process parameters including solvent, pH, and metal-ligand pair allowed for control over the film properties such as thickness and roughness. On the basis of these investigations, a potential route for the formation of spray-assembled MPN films was proposed. Conditions favoring the formation of bis complexes could produce thicker coatings than those favoring the formation of mono or tris complexes. Finally, the spray-assembled MPNs were used to generate superhydrophilic membranes for oil-water separation and colorless films for UV shielding. The present study provides insights into the chemistry of MPN assembly and holds promise for advancing the fabrication of multifunctional hybrid materials.
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ItemNo Preview AvailableSelf-Assembly of Nano- to Macroscopic Metal–Phenolic Materials(American Chemical Society, 2018)The self-assembly of molecular building blocks into well-defined macroscopic materials is desirable for developing emergent functional materials. However, the self-assembly of molecules into macroscopic materials remains challenging, in part because of limitations in controlling the growth and robustness of the materials. Herein, we report the molecular self-assembly of nano- to macroscopic free-standing materials through the coordination of metals with natural phenolic molecules. Our method involves a simple and scalable solution-based template dipping process in precomplexed metal–phenolic solutions, enabling the fabrication of free-standing macroscopic materials of customized architectures (2D and 3D geometries), thickness (about 10 nm to 5 μm), and chemical composition (different metals and phenolic ligands). Our macroscopic free-standing materials can be physically folded and unfolded like origami, yet are selectively degradable. Furthermore, metal nanoparticles can be grown in the macroscopic free-standing films, indicating their potential for future applications in biotechnology and catalysis.
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ItemSelf-Assembled Metal-Phenolic Networks on Emulsions as Low-Fouling and pH-Responsive Particles(WILEY-V C H VERLAG GMBH, 2018-09-27)Interfacial self-assembly is a powerful organizational force for fabricating functional nanomaterials, including nanocarriers, for imaging and drug delivery. Herein, the interfacial self-assembly of pH-responsive metal-phenolic networks (MPNs) on the liquid-liquid interface of oil-in-water emulsions is reported. Oleic acid emulsions of 100-250 nm in diameter are generated by ultrasonication, to which poly(ethylene glycol) (PEG)-based polyphenolic ligands are assembled with simultaneous crosslinking by metal ions, thus forming an interfacial MPN. PEG provides a protective barrier on the emulsion phase and renders the emulsion low fouling. The MPN-coated emulsions have a similar size and dispersity, but an enhanced stability when compared with the uncoated emulsions, and exhibit a low cell association in vitro, a blood circulation half-life of ≈50 min in vivo, and are nontoxic to healthy mice. Furthermore, a model anticancer drug, doxorubicin, can be encapsulated within the emulsion phase at a high loading capacity (≈5 fg of doxorubicin per emulsion particle). The MPN coating imparts pH-responsiveness to the drug-loaded emulsions, leading to drug release at cell internalization pH and a potent cell cytotoxicity. The results highlight a straightforward strategy for the interfacial nanofabrication of pH-responsive emulsion-MPN systems with potential use in biomedical applications.
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ItemSynthesis of Metal Nanoparticles in Metal-Phenolic Networks: Catalytic and Antimicrobial Applications of Coated Textiles(WILEY, 2018-03-07)The synthesis of metal nanoparticle (NP)-coated textiles (nanotextiles) is achieved by a dipping process in water without toxic chemicals or complicated synthetic procedures. By taking advantage of the unique nature of tannic acid, metal-phenolic network-coated textiles serve as reducing and stabilizing sites for the generation of metal nanoparticles of controllable size. The textiles can be decorated with various metal nanoparticles, including palladium, silver, or gold, and exhibit properties derived from the presence of the metal nanoparticles, for example, catalytic activity in water (>96% over five cycles using palladium nanoparticles) and antibacterial activity against Gram-negative bacteria (inhibition of Escherichia coli using silver nanoparticles) that outperforms a commercial bandage. The reported strategy offers opportunities for the development of hybrid nanomaterials that may have application in fields outside of catalysis and antimicrobials, such as sensing and smart clothing.