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Molecular mechanism of chitin and chitosan during the reacetylating process
임찬웅,황동수,이동욱 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-
The most plentiful component of exoskeletons in invertebrates is chitin, which is the second most abundant naturally occurring biopolymer by living organisms. And chitosan, one of the most important derivative of chitin, is an appealing biopolymer for the replacement of synthetic plastics and applicable to various biomedical fields. Here, we measured the interaction forces of chitosan (adhesion and cohesion) in aqueous solutions by exploring the effects of molecular weight (135 k & 5 k), contact time and degree of acetylation (DA) using a surface forces apparatus. The DA, which determines the chitin and chitosan, was precisely regulated by acetic anhydrides inducing the reacetylation of chitosan. The measured adhesion forces decreased as an increase of DA regardless of the molecular weight, while only the cohesion of 5 k chitosan increased as DA. These findings will provide a new insight into the future applications of chitin and chitosan based materials.
Nanomechanics of chitosan and chitin using an SFA
임찬웅,이동욱 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
The major component of exoskeletons in invertebrates such as crustaceans and instects is chitin, which is the second abundant naturally occurring biopolymer by living organisms after cellulose. And chitosan is an appealing biopolymer for the replacement of synthetic plastic compounds and applicable to various biomedical fields. Here, we measured molecular interactions of high molecular weight chitosan and low molecular weight chitosan in aqueous solutions by exploring the effects of pH, contact time and degree of acetylation which determines chitin and chitosan using a surface forces apparatus (SFA). The SFA is a powerful instrument used to characterize the fundamental molecular forces such as electrostatic forces, van der Waals forces, hydrophobic interactions, metal coordination forces in aqueous conditions. The nanomechanical studies of chitosan and chitin using SFA will provide a new insight into the development of chitosan/chitin based biomedical applications.
Nanomechanical analysis between a model cellular membrane and polyhexamethylene guanidine
임찬웅,이동욱 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
Wide range of pollutants, toxins, antibiotics or antimicrobial compounds interact with biological membranes, and precise evaluations of the molecular interactions between biological membranes and the potentially toxic chemicals are essential to foresee the toxicity and bioavailability of existing or newly synthesized molecules. In this study, surface forces apparatus measurement and Langmuir trough based tensiometry are performed to reveal molecular interaction mechanisms between potentially toxic compounds and biological membranes for ex vivo toxicity evaluation. As a toxic compound, polyhexamethylene guanidine (PHMG) was selected because PHMG containing humidifier disinfectant and Vodka caused lots of victims in both S. Korea and Russia, respectively, due to the lack of holistic evaluation of the toxicity of PHMG. We demonstrated potential of using SFA and LB tensiometry as toxicology testing methods by showing that only PHMG strongly interacts with biological membrane interface.
Superior Antifouling Properties of Bioinspired Ambivalent Block Copolyethers
임찬웅,김병수,이동욱 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-
PEG has attracted significant interest because of its excellent antifouling properties and high solubility and biocompatibility. However, the translation of its antifouling properties onto target surfaces has been challenging due to its limited functionality. Herein, we studied the antifouling properties of loop-like triblock copolyethers functionalized with catechol, a mussel-inspired, versatile moiety for coating, exclusively within a framework of polyethers. A series of catechol-functionalized polyethers with diverse molecular weights and catechol contents were synthesized via anionic ring-opening polymerization in a controlled manner. The versatile adsorption and antifouling effects of ambivalent block copolyethers were evaluated using a QCM-D. Furthermore, the crucial effects of the topology in the antifouling properties was analyzed via an SFA and MD simulations. This result demonstrates the catechol-functionalized triblock copolymer shows excellent antifouling properties.
Amphiphilic adhesive mechanism of Hydroxypropyl methylcellulose
임찬웅,송영훈,서정현,황동수,이동욱 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-
Hydroxypropyl methylcellulose (HPMC), a FDA approved water-soluble cellulose derivative, has played as a binder in a variety of applications in construction products, paints, and drug delivery. In spite of these many applications of HPMC as a binder, its adhesion mechanism is not well understood. In this study, we measured adhesion characteristics of HPMC in different hydrophobicity, water content, and temperature. The adhesion of HPMC were not affected by surface hydrophobicity in both bulk compression test and nano-mechanical test by surface forces apparatus, but strongly influenced by temperature and water content. The results indicate water content and temperature are critical variable for the adhesion of HPMC to inorganic surfaces. As adhesive and coating technologies have shifted towards environmentally friendly systems, these results provide a starting point for the fabrication of HPMC-based composites for a variety of future applications.