受賞概要

2021年7月7日（水）～9日（金）に、第12回AMF (The Asian Meeting on Ferroelectricity)と第11回AMEC (The Asian Meeting on Electroceramics)の共催であるAMF-AMEC2021がオンラインで開催されました。この国際学会において、ナノ高分子材料研究室のKamolchanok Sarisutaさん（M2）が、「Best Oral Presentation Award」を受賞しました。この国際会議では、学会、国立研究所、産業研究開発部門の研究者達が参加しました。本学会の目的は、材料科学と技術、材料処理と特性評価、および新しいアプリケーションとデバイスの開発における最新の進歩について議論することです。この趣旨のもと、約300名が参加し、研究発表要旨は199件、基調講演6件、招待講演52件、口頭発表74件、およびポスター発表67件が実施されました。本賞は、口頭発表およびポスター発表者が審査され、合計10件が選出されました。
【写真左から Kamolchanok Sarisutaさん、網代 広治教授】

研究題目・論文タイトル

pH-Responsive Aggregation of Poly(L-lactide) Particles Bearing Hydrophilic Moiety Connected with Vanillin and Cyclic Acetal.

研究者・著者

Kamolchanok Sarisuta, Mizuho Iwami, Nalinthip Chanthaset, Hiroharu Ajiro

受賞者コメント

I would like to express my sincere gratitude to my supervisor, Prof. Hiroharu Ajiro and Asst. Prof. Nalinthip Chanthaset for their excellent guidance, valuable advice, and encouragement throughout the course of this work. Appreciation continues to all member in Nanomaterials and Polymer Chemistry laboratory for their constantly support. This award is a great honor and privilege to encourages me to seek continued research excellence.

受賞対象となった研究の内容

pH-Responsive Aggregation of Poly(L-lactide) Particles Bearing Hydrophilic Moiety Connected with Vanillin and Cyclic Acetal

Kamolchanok Sarisuta,^a Mizuho Iwami,^a Nalinthip Chanthaset, ^a,* Hiroharu Ajiro^{a,b, *}

^aNara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara, 630-0192, Japan

^bData Science Center, 8916-5 Takayama, Ikoma, Nara, 630-0192, Japan

Keywords: POLYLACTIDE, VANILLIN, FUNCTIONALIZED CHAIN-END, pH-RESPONSE

Regarding periodontal disease is a major cause of tooth loss. To achieve the new drug carrier materials for prevention the disease, the biodegradable polymers with chain-end modification for improve pH-responsive were designed. Previously, we have been originally designed the biomass-based initiators for pH-responsive polymer such as vanillin and 5-hydroxymethylfurfural. Interestingly, imines-amines conversion was able to use as a key responsive for cutting off the hydrophilic moieties on the surface of poly(L-lactide) (PLLA) bearing hydrophilic moiety at acidic condition. The aldehyde groups of vanillin[1] and 5-hydroxymethylfurfural[2] were employed for the pH-responsive behaviors. However, the range of pH of the previous studies could not apply for actual medical application due to the required hydrolysis under severe condition at pH 2.

In this study, PLLA with the chain-end modification by ketone acetal bond were designed to improve pH-responsiveness. We also investigated the effect of the polymer molecular weight (M_n), pH range, and chain end structure. PLLA particles with hydrophilic moiety connected by vanillin-based initiators are featured in the design of five- and six-membered ring diol-ketone acetal which derives from vanillin and diol triethylene glycol (diol-OEG3). Then, PLA particles with a vanillin-functionalized chain end are prepared using a polymer with various M_n in the range of 1,100-5,500 g/mol. The chain end structure, particle size, and morphology of the obtained particles are thoroughly measured by NMR, UV, Mass-spectrometer, FTIR, GPC, SEM, and DLS. These results indicate that a chain end with a six-membered ring acetal derivative is aggregated more rapidly than a five-membered ring. Regarding the rate of hydrolysis, de-cyclization of a six-membered ring at pH 5.6 is generated within 1.5 minutes while at pH 6.0, it is 2.5 minutes.

It is expected that the present results will contribute to oral health care research in the future, because the control of particle aggregation rate under physiological conditions could be controlled by the molecular weight of PLA, and the ring-type cyclic diol-ketone acetal.

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