Bacterial LIVE/DEAD Staining

The LIVE/DEAD^® BacLight^TM Bacterial Viability Kit (L7012, Thermo Scientific, United States) was used to distinguish live and dead bacteria. After incubation the samples were rinsed with PBS then incubated with 200 μL LIVE/DEAD^® BacLight^TM solution prepared in accordance with the manufacturer’s instructions at room temperature in the dark for 15 min. The SYTO 9 in the solution causes the live bacteria to emit green fluorescence, and the propidium iodide in the solution causes dead bacteria to emit red fluorescence. Confocal laser scanning microscopy (CLSM) (Nikon A1 plus, Japan) was used to assess the samples. Image-Pro Plus was used to perform quantitative analysis to evaluate bacterial adhesion based on the determination of fluorescence intensity in each captured image. Results were obtained from three captured images and normalized to the green/total fluorescence intensity of PLLA samples and red fluorescence intensity of 15%Li samples.