Chemical and Biomolecular Engineering - Research Publications
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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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ItemSuperassembled Biocatalytic Porous Framework Micromotors with Reversible and Sensitive pH-Speed Regulation at Ultralow Physiological H2O2 Concentration(WILEY-V C H VERLAG GMBH, 2019-05-02)Synthetic nano/micromotors are a burgeoning class of materials with vast promise for applications ranging from environmental remediation to nanomedicine. The motility of these motors is generally controlled by the concentration of accessible fuel, and therefore, engineering speed‐regulation mechanisms, particularly using biological triggers, remains a continuing challenge. Here, control over the movement of superassembled porous framework micromotors via a reversible, biological‐relevant pH‐responsive regulatory mechanism is demonstrated. Succinylated β‐lactoglobulin and catalase are superassembled in porous framework particles, where the β‐lactoglobulin is permeable at neutral pH. This permeability allows the fuel (H2O2) to access catalase, leading to autonomous movement of the micromotors. However, at mild acidic pH, succinylated β‐lactoglobulin undergoes a reversible gelation process, preventing the access of fuel into the micromotors where the catalase resides. To one's knowledge, this study represents the first example of chemically driven motors with rapid, reversible pH‐responsive motility. Furthermore, the porous framework significantly enhances the biocatalytic activity of catalase, allowing ultralow H2O2 concentrations to be exploited at physiological conditions. It is envisioned that the simultaneous exploitation of pH and chemical potential of such nanosystems could have potential applications as stimulus‐responsive drug delivery vehicles that benefit from the complex biological environment.
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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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ItemThermal Transition of Bimetallic Metal-Phenolic Networks to Biomass-Derived Hierarchically Porous Nanofibers(WILEY-V C H VERLAG GMBH, 2018-04-16)The development and utilization of biomass resources could contribute to new materials for long-term sustainable energy storage and environmental applications, reduce environmental impacts, and meet the urgent need for green and sustainable development strategies. Herein, a bimetallic metal-phenolic network (MPN) was applied to incorporate different metallic element species into cattle skin and fabricate collagen-fiber-derived complex oxide nanofibers using natural polyphenols (Myrica tannins). Direct thermal transition of these biomass-MPN composites generates hierarchically porous nanofibers possessing micro- and mesoporous architectures along with a well-preserved macroscopic structure. The pore system and complex oxide composition provide excellent photocatalytic performance. This low-cost, simple, and readily scalable MPN-based approach provides a straightforward route to synthesize nanostructured materials directly from biomass, which could play important roles in a wide range of potential applications.
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ItemTargeted Therapy against Metastatic Melanoma Based on Self-Assembled Metal-Phenolic Nanocomplexes Comprised of Green Tea Catechin(WILEY, 2019-03-06)The targeted therapy of metastatic melanoma is an important yet challenging goal that has received only limited attention to date. Herein, green tea polyphenols, (–)‐epigallocatechin‐3‐gallate (EGCG), and lanthanide metal ions (Sm3+) are used as building blocks to engineer self‐assembled SmIII‐EGCG nanocomplexes with synergistically enhanced tumor inhibitory properties. These nanocomplexes have negligible systemic toxic effects on healthy cells but cause a significant reduction in the viability of melanoma cells by efficiently regulating their metabolic pathways. Moreover, the wound‐induced migration of melanoma cells can be efficiently inhibited by SmIII‐EGCG, which is a key criterion for metastatic melanoma therapy. In a mouse melanoma tumor model, SmIII‐EGCG is directly compared with a clinical anticancer drug, 5‐fluorouracil and shows remarkable tumor inhibition. Moreover, the targeted therapy of SmIII‐EGCG is shown to prevent metastatic lung melanoma from spreading to main organs with no adverse side effects on the body weight or organs. These in vivo results demonstrate significant advantages of SmIII‐EGCG over its clinical counterpart. The results suggest that these green tea‐based, self‐assembled nanocomplexes possess all of the key traits of a clinically promising candidate to address the challenges associated with the treatment of advanced stage metastatic melanoma.
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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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ItemExpression of Programmed Cell Death-Ligands in Hepatocellular Carcinoma: Correlation With Immune Microenvironment and Survival Outcomes(FRONTIERS MEDIA SA, 2019-09-11)The quantity of programmed cell death-ligand 1 (PD-L1) is regarded as a predicting factor of clinical response to anti-PD-1 axis immunotherapy. However, the expression of PD-L1 and its prognostic value in hepatocellular carcinoma (HCC) patients remain debated. Meanwhile, the molecular features of PD-1's other ligand, namely PD-L2, as well as its correlation with clinicopathological parameters and HCC tumor microenvironment (TME), are still poorly understood. In this study, immunohistochemistry (IHC) data from 304 HCC patients were used to determine the clinicopathological features of PD-L1 and PD-L2 and their correlation with CD8+ T cells in HCC. Moreover, fresh clinical HCC samples were used to identify the immune cell subtypes expressing PD-L1 and PD-L2. By using The Cancer Genome Atlas (TCGA) dataset, we further assessed the correlation between mutation signature, copy number variation (CNV), number of neoepitopes, immune gene expression, immune/stromal cell infiltration to the expression of PD-L1 and PD-L2. While membrane expression of PD-L2 was observed in 19.1% of tumor samples, no obvious expression of PD-L1 was detected on tumor cell membranes. High expression of PD-L2 on tumor membranes and PD-L1 in immune stroma were both significantly associated with poorer overall survival (OS) and disease-free survival (DFS) outcomes. Flow cytometry analysis and immunofluorescence showed that macrophages were the main immune cell subtype expressing both PD-L1 and PD-L2. Moreover, positive expression of PD-Ls was correlated with higher CD8+ T cells infiltration in immune stroma. CNV analysis showed a similarity between PD-L1 and PD-L2 in affecting gene expression. In addition, higher levels of PD-Ls correlated with higher expression of immune related genes, enhanced cytolytic activity, and larger proportions of immune/stromal cell infiltration. Collectively, our study reveals the impact of both PD-L1 and PD-L2 on the HCC tumor microenvironment for the first time, providing insight for new therapeutic options.
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ItemLigand-Functionalized Poly(ethylene glycol) Particles for Tumor Targeting and Intracellular Uptake.(American Chemical Society, 2019)Drug carriers typically require both stealth and targeting properties to minimize nonspecific interactions with healthy cells and increase specific interaction with diseased cells. Herein, the assembly of targeted poly(ethylene glycol) (PEG) particles functionalized with cyclic peptides containing Arg-Gly-Asp (RGD) (ligand) using a mesoporous silica templating method is reported. The influence of PEG molecular weight, ligand-to-PEG molecule ratio, and particle size on cancer cell targeting to balance stealth and targeting of the engineered PEG particles is investigated. RGD-functionalized PEG particles (PEG-RGD particles) efficiently target U-87 MG cancer cells under static and flow conditions in vitro, whereas PEG and cyclic peptides containing Arg-Asp-Gly (RDG)-functionalized PEG (PEG-RDG) particles display negligible interaction with the same cells. Increasing the ligand-to-PEG molecule ratio improves cell targeting. In addition, the targeted PEG-RGD particles improve cell uptake via receptor-mediated endocytosis, which is desirable for intracellular drug delivery. The PEG-RGD particles show improved tumor targeting (14% ID g-1) when compared with the PEG (3% ID g-1) and PEG-RDG (7% ID g-1) particles in vivo, although the PEG-RGD particles show comparatively higher spleen and liver accumulation. The targeted PEG particles represent a platform for developing particles aimed at balancing nonspecific and specific interactions in biological systems.
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ItemOxidation-Mediated Kinetic Strategies for Engineering Metal-Phenolic Networks(Wiley - V C H Verlag GmbH & Co. KGaA, 2019-09-02)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.