Photobiomodulation (PBM) has been shown to improve cell proliferation and cell migration. Many cell types have been 
investigated, with most studies using deep penetrating red light irradiation. Considering the interest of surface biostimulation 
of oral mesenchymal cells after surgical wound, the present study aimed to assess green light irradiation effects on Dental Pulp 
Stem Cells’ (DPSC) proliferation and migration. To understand the mechanisms underlying these effects, we investigated 
cytoskeleton organization and subsequent cell shape and stiffness. 
A 532-nm wavelength Nd:YAG laser (30 mW) was applied 
between 30 and 600 s on DPSC in vitro. Cell proliferation was analyzed at 24, 48, and 72 h after irradiation, by cell counting and enzymatic activity quantification (paranitrophenylphosphate phosphatase (pNPP) test). A wound healing assay was used to study 
cell migration after irradiation. Effects of PBM on cytoskeleton organization and cell shape were assessed by actin filaments 
staining. Elasticity changes after irradiation were quantified in terms of Young’s modulus measured using Atomic Force 
Microscopy (AFM) force spectroscopy. Green light significantly improved DPSC proliferation with a maximal effect obtained after 300-s irradiation (energy fluence 5 J/cm2). This irradiation had a significant impact on cell migration, improving wound 
healing after 24 h. These results were concomitant with a decrease of cells’ Young’s modulus after irradiation. This cell softening 
was explained by actin cytoskeleton reorganization, with diminution of cell circularity and more abundant pseudopodia. This 
study highlights the interest of green laser PMB for the proliferation and migration of mesenchymal stem cells, with encouraging 
results for clinical application, especially for surgical wound healing procedures. 


In recent years, uorescent nanodiamond (fND) particles containing nitrogen-vacancy (NV) centers gained recognition as an attractive probe for nanoscale cellular imaging and quantum sensing. For these applications, precise localization of fNDs inside of a living cell is essential. Here we propose such a method by simultaneous detection of the signal from the NV centers and the spectroscopic Raman signal from the cells to visualize the nucleus of living cells. However, we show that the commonly used Raman cell signal from the ngerprint region is not suitable for organelle imaging in this case. Therefore, we develop a method for nucleus visualization exploiting the region-speci c shape of C-H stretching mode and further use k-means cluster analysis to chemically distinguish the vicinity of fNDs. Our technique enables, within a single scan, to detect fNDs, distinguish by chemical localization whether they have been internalized into cell and simultaneously visualize cell nucleus without any labeling or cell- xation. We show for the rst time spectral colocalization of unmodi ed high-pressure high-temperature fND probes with the cell nucleus. Our methodology can be, in principle, extended to any red- and near-infrared-luminescent cell-probes and is fully compatible with quantum sensing measurements in living cells.