Use of a mid-infrared free-electron laser to treat infectious diseases: Its bactericidal effects against gram-negative bacteria

2021 Fiscal Year Final Research Report

• Project/Area Number: 18K09895
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 57080:Social dentistry-related
• Research Institution: Kanagawa Dental College
• Principal Investigator: Toyama Toshizo 神奈川歯科大学, 歯学部, 特任講師 (60638906)
• Co-Investigator(Kenkyū-buntansha): 吉田 彩佳 神奈川歯科大学, 歯学部, 准教授 (00609414) ; 築山 光一 東京理科大学, 理学部第一部化学科, 教授 (20188519) ; 浜田 信城 神奈川歯科大学, 歯学部, 教授 (20247315) ; 吉野 文彦 神奈川歯科大学, 歯学部, 准教授 (20308307)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Keywords: 赤外自由電子レーザー / Porphyromonas gingivalis / Escherichia coli / aPDT / 歯周病

Outline of Final Research Achievements

This study is based on the bactericidal effect of FEL on periodontopathic bacteria such as Porphyromonas gingivalis and Escherichia coli as endemic Gram-negative bacteria, and the effect of infrared free electron laser on periodontopathic bacteria was evaluated by analyzing the infrared absorption wavelengths of various bacteria and irradiating them with various wavelengths determined. The results showed that the laser's bactericidal effect was significantly enhanced by irradiation at wavelengths up to 6.62micrometre. As a result, the antibacterial effect was observed at the wavelength of 6.62micrometre, which corresponds to the C-H stretching vibration mode. The 6.62micrometre irradiation group was the most superior to the other wavelengths in inhibiting bacterial growth.

Free Research Field

細菌学

Academic Significance and Societal Importance of the Research Achievements

赤外自由電子レーザー (FEL) は中赤外領域を発振領域とする波長可変のレーザーであり，その波長域は分子の指紋領域をほぼ全域網羅しているため，殺菌作用のみならず，LPSなど細菌特有な分子の不活化が期待できるが，歯周病治療への応用はされていない。本研究課題では，FEL が照射範囲にある組織に対して温度変化をおこすことなく，人体に為害作用が少ない光線力学療法が可能であることが示唆された。