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  4. Ms. Kamolchanok Sarisuta (M2) of Nanomaterials and Polymer Chemistry Laboratory received the Best Oral Presentation Award at AMF-AMEC2021.

Ms. Kamolchanok Sarisuta (M2) of Nanomaterials and Polymer Chemistry Laboratory received the Best Oral Presentation Award at AMF-AMEC2021.

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AMF-AMEC2021, which is 12th AMF (The Asian Meeting on Ferroelectricity) and the 11th AMF (The Asian Meeting on Electroceramics), was held during July 7th and 9th, 2021. Mr. Kamolchanok Sarisuta (M2) from the Nanomaterials and Polymer Chemistry Laboratory received the "Best Oral Presentation Award". Researchers from academic societies, national laboratories, and industrial research and development departments participated in this international conference. The purpose of the conference was the discussion on the latest advances in materials science and technology, material handling and characterization, and the development of new applications and devices. In the conference, about 300 people participated, and 199 research presentations, 6 keynote lectures, 52 invited lectures, 74 oral presentations, and 67 poster presentations were achieved. The award was judged by oral presentations and poster presenters, and a total of 10 prizes were selected.
【From left to right, Ms. Kamolchanok Sarisuta, Professor Hiroharu Ajiro】

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

Kamolchanok Sarisuta, Mizuho Iwami, Nalinthip Chanthaset, Hiroharu Ajiro

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 encourage me to seek continued research excellence.

Regarding periodontal disease is a major cause of tooth loss. To achieve the new drug carrier materials for prevention of the disease, the biodegradable polymers with chain-end modification for improved 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 was designed to improve pH-responsiveness. We also investigated the effect of the polymer molecular weight (Mn), pH range, and chain end structure. PLLA particles with hydrophilic moiety connected by vanillin-based initiators were 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 were prepared using a polymer with various Mn in the range of 1,100-5,500 g/mol. The chain end structure, particle size, and morphology of the obtained particles were thoroughly measured by NMR, UV, Mass-spectrometer, FTIR, GPC, SEM, and DLS. These results indicated that a chain end with a six-membered ring acetal derivative was aggregated more rapidly than a five-membered ring. Regarding the rate of hydrolysis, de-cyclization of a six-membered ring at pH 5.6 was 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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