Antimicrobial effect of photodynamic therapy using sinoporphyrin sodium and 390-400nm light-emitting diode on Porphyromonas gingivalis in vitro.

Abstract

This study aims to investigate the effect of antimicrobial photodynamic therapy (a-PDT) using a novel combination of sinoporphyrin sodium (DVDMS) and light-emitting diode (LED) with a wavelength of 390-400nm on Porphyromonas gingivalis in vitro. Absorption spectrum of DVDMS was determined by spectrometer for selecting suitable wavelength light source. The uptake of DVDMS by P. gingivalis was evaluated according to fluorescence intensity detected by a spectrometer. Then effects of DVDMS alone, 390-400nm LED alone, and photodynamic therapy produced by 10, 20, 40, and 80μg/mL DVDMS and 390-400nm LED on the suspension of P. gingivalis were evaluated by counting the number of colony forming units (CFU) after incubation. In the experiment, the LED illumination time was 30, 60, 90, 120, 180, 240, and 360s, respectively, and the corresponding energy density was 1, 2, 3, 4, 6, 8, and 12J/cm2, respectively. According to the absorption spectrum of DVDMS, the 390-400-nm light emitted by the LED was selected as the light source. The fluorescence intensity of DVDMS on P. gingivalis increased significantly at 5min, and with the extension of time, it decreased at 30min. DVDMS alone did not produce a significant toxicity on P. gingivalis compared with PBS (p = 0.979). While 390-400nm LED alone had a certain bactericidal effect on P. gingivalis, the bactericidal effect was more obvious as the light dose increased (p < 0.001). The effect of a-PDT produced by 20, 40, and 80μg/mL DVDMS and 390-400nm LED were significantly better than that of 390-400nm LED alone (p < 0.05). Both DVDMS concentration and light dose could enchance the bactericidal effect. The strongest photo-killing effect was generated by 80μg/mL DVDMS with 360s illumination (energy density is 12J/cm2), and the log reduction of bacteria was 5.69 ± 1.70. a-PDT using the combination of DVDMS with 390-400nm LED shows promise as a new treatment modality for pathogens elimination in periodontal therapy.