Fig 1.
A) sketch of the plasma brush, B) Experimental flow chart of the direct plasma destruction on biofilms, C) Experimental flow chart of the biofilm recovery after plasma treatment.
Fig 2.
MTT assay results of the change of survival percentage of 3-day P. gingivalis biofilms with plasma treatment time.
* denotes statistically significant difference compared with the control group with p < 0.05. Treatment time of 0 minutes represents the untreated control group.
Fig 3.
CFU counting results of plasma destruction of 3-day P. gingivalis biofilms after different plasma treatment times.
Treatment time of 0 minutes represents the untreated control group. * denotes statistically significant difference compared with the control group with p<0.05 according to ANOVA Tukey test. denotes the statistically significant differences among different treatment times of pure argon plasma with p<0.05 according to ANOVA Tukey test. denotes the statistically significant differences among different treatment times of argon+1% oxygen plasma with p<0.05 according to ANOVA Tukey test.
Fig 4.
MTT assay results of plasma destruction of 5-day P. gingivalis biofilms.
* denotes statistically significant difference compared with the control group with p < 0.05 according to ANOVA Tukey test. # denotes statistically significant difference between pure argon plasma and argon+1% oxygen plasma treatments with p < 0.05 according to ANOVA Tukey test. denotes the statistically significant differences among different treatment times of argon+1% oxygen plasma with p < 0.05 according to ANOVA Tukey test.
Fig 5.
CFU counting assay results of argon+1% oxygen plasma destruction of 3-day and 5-day P. gingivalis biofilms.
* denotes the statistically significant difference compared with the untreated control groups with p < 0.05. # denotes the statistically significant difference between 3-day and 5-day biofilms with p < 0.05 according to ANOVA Tukey test. denotes the statistically significant differences among different treatment times of 3-day biofilms with p<0.05 according to ANOVA Tukey test. denotes the statistically significant differences among different treatment times of 5-day biofilms with p < 0.05 according to ANOVA Tukey test.
Fig 6.
CLSM images of 3-day P. gingivalis biofilms.
2D images of: A) Untreated control, B) 1-min argon+1% oxygen plasma treatment, C) 5-min argon+1% oxygen plasma treatment; 3D images of: D) Untreated control, E) 1-min argon+1% oxygen plasma treatment, F) 5-min argon+1% oxygen plasma treatment.
Fig 7.
Bacterial recovery results from (A) MTT assay and (B) CFU counting assay for untreated and 1-min argon+1% oxygen plasma treated 3-day P. gingivalis biofilms.
Fig 8.
Antibiotic susceptibility results from (A) MTT assay and (B) CFU counting assay for untreated and 1-min argon+1% oxygen plasma treated 3-day P. gingivalis biofilms.
* denotes the statistically significant difference (p < 0.05) compared with the control groups without amoxicillin application (0 μg/ml). # denotes the statistically significant difference (p < 0.05) between untreated controls and plasma treated groups.
Fig 9.
Biofilm recovery results under oxidative stress of H2O2 from (A) MTT assay and (B) CFU counting assay for untreated and 1-min argon+1% oxygen plasma treated 3-day P. gingivalis biofilms.
* denote the statistically significant difference (p < 0.05) compared with the control groups without H2O2 treatment. # denotes the statisticall significant difference (p < 0.05) between untreated controls and plasma treated groups. denotes the statistically significant differences among different H2O2 doses for non-plasma treated biofilms with p < 0.05 according to ANOVA Tukey test. denotes the statistically significant differences among different H2O2 doses for plasma treated biofilms with p < 0.05 according to ANOVA Tukey test.
Fig 10.
Biofilm recovery results under oxidative stress of paraquat from (A) MTT assay and (B) CFU counting assay for untreated and 1-min argon+1% oxygen plasma treated 3-day P. gingivalis biofilms. * denote the statistically significant difference (p < 0.05) compared with the control groups without paraquat treatment. # denotes the statistically significant difference (p < 0.05) between untreated controls and plasma treated groups. denotes the statistically significant differences among different paraquat doses for non-plasma treated biofilms with p < 0.05 according to ANOVA Tukey test. denotes the statistically significant differences among different paraquat doses for plasma treated biofilms with p < 0.05 according to ANOVA Tukey test.