Seonki Hong

Mussel‐Inspired Adhesive Binders for High‐Performance Silicon Nanoparticle Anodes in Lithium‐Ion Batteries

Conjugation of mussel-inspired catechol groups to various polymer backbones results in materials suitable as silicon anode binders. The unique wetness-resistant adhesion provided by the catechol groups allows the silicon nanoparticle electrodes to maintain their structure throughout the repeated volume expansion and shrinkage during lithiation cycling, thus facilitating substantially improved specific capacities and cycle lives of lithium-ion batteries.

Attenuation of the in vivo toxicity of biomaterials by polydopamine surface modification

AIMS Polydopamine coating is emerging as a useful method of surface functionalization due to the ability of this compound to form a nanometer-scale organic thin film on virtually any material surface to which proteins, peptides, oligonucleotides, metal ions or synthetic polymers are able to be attached. The unique properties of polydopamine make this technique suitable for nanomedicine. To facilitate the use of polydopamine, evaluation of toxicity is of great importance. In this article, we investigated the in vivo toxicity of polydopamine. RESULTS We found that the polydopamine functions as a biocompatible layer, attenuating adverse biological responses caused by intrinsic properties of the coated material. One-step polydopamine coating greatly reduced the inflammatory response to poly-L-lactic acid surfaces and the immunological responses of blood on quantum dots were also reduced. CONCLUSION Our results indicate that polydopamine provides a versatile platform that can reduce the in vivo toxicity of biomaterials that contact tissue or blood.

Mussel‐Inspired Block Copolymer Lithography for Low Surface Energy Materials of Teflon, Graphene, and Gold

Mussel-inspired interfacial engineering is synergistically integrated with block copolymer (BCP) lithography for the surface nanopatterning of low surface energy substrate materials, including, Teflon, graphene, and gold. The image shows the Teflon nanowires and their excellent superhydrophobicity.

High‐Strength Carbon Nanotube Fibers Fabricated by Infiltration and Curing of Mussel‐Inspired Catecholamine Polymer

Carbon nanotubes (CNTs) have received extensive attention due to their extraordinary properties in electronic conduction, [ 1 ] heat transfer, [ 2 ] and mechanical strength. [ 3 ] Materials with unparallel performance, such as super-strong, lightweight e-textiles, can be fabricated from CNTs, suggesting a future revolution in materials science. Thus, the emerging CNT technology will largely depend on the development of effective spinning and post-spinning processes to realize such unprecedented materials. Two widely implemented strategies for fabricating CNT fi bers are in-solution [ 4–7 ] and solid-state spinning techniques. The in-solution spinning of CNTs can produce continuous CNT fi bers; however, homogeneous dispersion of CNTs in the solvent is necessary for proper spinning. Moreover, the properties of the CNT fi bers strongly depend on the methods of CNT dispersion. An alternative strategy is solid-state spinning, [ 8–17 ] which allows avoidance of CNT dispersion in solvents and for various post-spinning processes to be applied with ease. Twisting, [ 10–16 ] densifi cation, [ 9 , 18 ] and infi ltration [ 8 , 19,20 ] are examples of post-spinning processes, and the main purpose of the spinning and post-spinning processes is to enhance the mechanical properties of CNT fi bers. Despite the effort that has been made, however, fabrication of strong CNT fi bers remains a great challenge.

Bio-inspired adhesive catechol-conjugated chitosan for biomedical applications: A mini review

The development of adhesive materials, such as cyanoacrylate derivatives, fibrin glues, and gelatin-based adhesives, has been an emerging topic in biomaterial science because of the many uses of these materials, including in wound healing patches, tissue sealants, and hemostatic materials. However, most bio-adhesives exhibit poor adhesion to tissue and related surfaces due to the presence of body fluid. For a decade, studies have aimed at addressing this issue by developing wet-resistant adhesives. Mussels demonstrate robust wet-resistant adhesion despite the ceaseless waves at seashores, and mussel adhesive proteins play a key role in this adhesion. Adhesive proteins located at the distal end (i.e., those that directly contact surfaces) are composed of nearly 60% of amino acids called 3,4-dihydroxy-l-phenylalanine (DOPA), lysine, and histidine, which contain side chains of catechol, primary amines, and secondary amines, respectively. Inspired by the abundant catecholamine in mussel adhesive proteins, researchers have developed various types of polymeric mimics, such as polyethylenimine-catechol, chitosan-catechol, and other related catecholic polymers. Among them, chitosan-catechol is a promising adhesive polymer for biomedical applications. The conjugation of catechol onto chitosan dramatically increases its solubility from zero to nearly 60mg/mL (i.e., 6% w/v) in pH 7 aqueous solutions. The enhanced solubility maximizes the ability of catecholamine to behave similar to mussel adhesive proteins. Chitosan-catechol is biocompatible and exhibits excellent hemostatic ability and tissue adhesion, and thus, chitosan-catechol will be widely used in a variety of medical settings in the future. This review focuses on the various aspects of chitosan-catechol, including its (1) preparation methods, (2) physicochemical properties, and (3) current applications.

Water Detoxification by a Substrate-Bound Catecholamine Adsorbent

Ensuring an adequate supply of clean water is an urgent global issue. In 1992, the United Nations (UN) designated March 22 of every year as World Water Day (WWD) to increase awareness of the importance of clean water conservation. Also, Population Action International (PAI) has reported a shortage of fresh water in developing and under-developed countries. The demand for clean water will continue to increase because of industrialization and population growth. Thus, the development of technologies that can effectively purify contaminated water has been an emerging area of research. Adsorption-based technologies have been used to remove a variety of toxic chemicals from contaminated water through batch or continuous flow processes. The carboxyl and amine groups of activated carbon and polysaccharides such as alginate and chitosan are the most widely implemented adsorbents owing to their ability to chelate toxic heavy metals. However, several limitations of existing adsorbents can be identified. First, the attachment of polysaccharides onto solid phases is essential, yet these adsorbents lack inherent adhesive properties to facilitate their immobilization onto substrates. Second, the generation of secondary pollutants during chemical processing of adsorbents is a serious environmental issue. In the case of activated carbon adsorbent, a strongly acidic solution—typically 10–50 % (v/v) HNO3—has been used. [5] Third, the variety of toxic chemicals that can be removed by existing adsorbents is limited—they often show excellent performance in the removal of heavy metals but perform poorly in the removal of toxic organic molecules, particularly in the case of polysaccharide adsorbents. Fourth, methods for regenerating adsorbents and isolating adsorbed toxic chemical complexes have not been adequately developed. Finally, the cost of carbon materials is rapidly increasing, a particular concern for developing and resource-poor settings. Thus, novel approaches to overcome the aforementioned limitations, in whole or in part, may lead to improved and more cost-effective water detoxification processes. Adaptations of chemical and physical principles found in the biological world can offer good alternative approaches to water detoxification. In this case, biological strategies that combine surface adhesion with the ability to isolate, bind, and sequester heavy metals and other toxins are of great interest. The proteins comprising the byssal attachments of marine mussels share many of these qualities. The byssal adhesive pads are effective at attaching to substrates, and have been reported to be enriched in various metals (Fe, Mn, Zn, Cu, Ni, etc.). As an indicator of the protein’s metal binding ability, the concentration of iron in dried byssus is approximately a million-fold higher than the typical concentration in seawater. Furthermore, the strong metal binding property of mussel byssus has led to investigations of byssal tissue as a sensitive biomonitoring organ for heavy metals in the marine environment. Thus, we hypothesize that a mussel-inspired approach combining the substrate adhesion and metal binding affinity of catechol and amine functional groups would be useful to remove toxic metals from contaminated water. Furthermore, quinones formed by catechol oxidation may provide additional capability of removing selected toxic organic compounds, as they are known to react with amines and thiols. In fact, we have demonstrated that this chemical reaction occurs at interfaces at the single-molecule level. Polydopamine is a synthetic mimic of mussel adhesive proteins that deposits as a thin (monolayer to 50 nm or more) coating on virtually any material by spontaneous oxidation of dopamine in an alkaline aqueous solution (Figure 1 b). Compared with other methods of coating substrates, polydopamine has the advantage of being inexpensive, adherent, and simple to deposit onto substrates without the need for surface pretreatment. Polydopamine nanolayers form on virtually any material surface, including noble metals, oxides, semiconductors, ceramics, synthetic polymers, and graphene oxide, as well as on superhydrophobic surfaces. The strength of catechol adhesion on TiO2 and gold surfaces was reported to be stronger than the well-known avidin–biotin interaction at a singlemolecule level, thus explaining the robustness of the polydopamine coating. The binding force on glass substrates, however, has not been reported, but it has been observed that the coating remained stable under vigorous mechanical stirring conditions ( 1000 rpm). Also, the catecholamines that do not participate in surface binding can perform a variety of chemical reactions, resulting in water detoxification. [a] M. Lee, S. Hong, Prof. H. Lee Department of Chemistry The Graduate School of Nanoscience and Technology Korea Advanced Institute of Science and Technology (KAIST) 335 Science Rd. Daejeon, 305-701 (South Korea) Fax: (+ 82) 42-350-2810 E-mail : haeshin@kaist.ac.kr [b] J. Rho, Prof. P. B. Messersmith Biomedical Engineering, Materials Science and Engineering Chemical and Biological Engineering Department Northwestern University, Evanston, IL 60208 (USA) Fax: (+ 1) 847-491-4928 E-mail : philm@northwestern.edu [c] Dr. D.-E. Lee, S.-J. Choi Radioisotope Research Division Research Reactor Utilization and Development KAERI, Daejeon, 305-353 (South Korea) [] These authors contributed equally to this work. Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/cplu.201200209.

Air/Water Interfacial Formation of Freestanding, Stimuli‐Responsive, Self‐Healing Catecholamine Janus‐Faced Microfilms

A catecholamine freestanding film is discovered to be spontaneously formed at the air-water interface, and the film has unique properties of robust surface adhesiveness, self-healing, and stimuli-responsive properties. The interfacial film-producing procedure is a simple single step containing polyamines and catechol(amine)s. It is found that oxygen-rich regions existing at an air-water interface greatly accelerate the catecholamine crosslinking reaction.

Improved cycle lives of LiMn2O4 cathodes in lithium ion batteries by an alginate biopolymer from seaweed

We report an alginate, extracted from brown seaweed as a polymeric binder for spinel LiMn2O4. The exceptional Mn2+ capture of the alginate extracted from brown seaweed resolves the chronic issue of a promising lithium battery cathode, LiMn2O4, upholding the feasibility of its use for emerging large-scale applications including electric vehicles.

Multiparametric plasma EV profiling facilitates diagnosis of pancreatic malignancy

A multiplexed plasmonic assay analyzes circulating tumor-derived extracellular vesicles for detection of pancreatic ductal adenocarcinoma. A signature achievement Pancreatic ductal adenocarcinoma is one of the deadliest types of tumors, in part because it is usually detected at a late stage. To facilitate the diagnosis of this tumor, Yang et al. developed a multiplexed plasmonic assay to evaluate extracellular vesicles in patient plasma for protein markers associated with the presence of pancreatic cancer. The authors identified a five-marker signature that yielded the most accurate diagnosis. To test their assay, the researchers analyzed samples from patients with pancreatic cancer and other types of pancreatic disease, as well as healthy controls, and confirmed the accuracy of their signature in prospectively collected samples. Pancreatic ductal adenocarcinoma (PDAC) is usually detected late in the disease process. Clinical workup through imaging and tissue biopsies is often complex and expensive due to a paucity of reliable biomarkers. We used an advanced multiplexed plasmonic assay to analyze circulating tumor-derived extracellular vesicles (tEVs) in more than 100 clinical populations. Using EV-based protein marker profiling, we identified a signature of five markers (PDACEV signature) for PDAC detection. In our prospective cohort, the accuracy for the PDACEV signature was 84% [95% confidence interval (CI), 69 to 93%] but only 63 to 72% for single-marker screening. One of the best markers, GPC1 alone, had a sensitivity of 82% (CI, 60 to 95%) and a specificity of 52% (CI, 30 to 74%), whereas the PDACEV signature showed a sensitivity of 86% (CI, 65 to 97%) and a specificity of 81% (CI, 58 to 95%). The PDACEV signature of tEVs offered higher sensitivity, specificity, and accuracy than the existing serum marker (CA 19-9) or single–tEV marker analyses. This approach should improve the diagnosis of pancreatic cancer.

Supramolecular Metallo-Bioadhesive for Minimally Invasive Use.

A novel metallo-bioadhesive to be used as tissue sealant in minimally invasive procedures is reported. Metal complexation can be used to render gelatin derivatives adhesive, which occurs in minutes, is efficient, and fully biodegradable within weeks.