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.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that selectively affects upper and lower motoneurons. Dismantlement of the neuromuscular junction (NMJ) is an early pathological hallmark of the disease whose cellular origin remains still debated. We developed an in vitro NMJ model to investigate the differential contribution of motoneurons and muscle cells expressing ALS-causing mutation in the superoxide dismutase 1 (SOD1) to neuromuscular dysfunction. The primary co-culture system allows the formation of func- tional NMJs and fosters the expression of the ALS-sensitive fast fatigable type II-b myosin heavy chain (MHC) iso- form. Expression of SOD1G93A in myotubes does not prevent the formation of a functional NMJ but leads to decreased contraction frequency and lowers the slow type I MHC isoform transcript levels. Expression of SOD1G93A in both motoneurons and myotubes or in motoneurons alone however alters the formation of a functional NMJ. Our results strongly suggest that motoneurons are a major factor involved in the process of NMJ dismantlement in an experimental model of ALS.

The development of new diagnostic technologies based on the light scattering and autofluorescence properties of den- tal tissues is required to improve the diagnostic ability of ini- tial caries lesions earlier than previously done and promot- ing the potential of treatment without surgical intervention. The aim of this study is to correlate fluorescence-based re- sults provided by multiphoton microscopy (MPM) with con- focal Raman microscopy records using phosphate level at 960 cm–1 and the organic matrix at ∼2,931 cm–1 in healthy and demineralized human enamel. Measurements on 14 teeth were made using two incident lights of different wave- lengths, released by confocal Raman microscopy and MPM. Raman phosphate peak intensity at 960 cm–1 along with or- ganic to mineral ratio at (2,931/430 cm–1) and nonlinear opti- cal signals (second harmonic generation [SHG] and intrinsic two-photon excited fluorescence [I2PEF]) were recorded from the demineralized and healthy enamel sites. Raman spectral maps showed that the higher the organic/mineral ratio in the demineralized enamel, the lower the intensity of mineral component in the same zone. MPM revealed new optical indicators of carious lesion as shown by the presence of a red-shifted fluorescence peak in the 650- to 750-nm area of the fluorescence spectrum of demineralized enamel. Moreover, on sample regions with insignificant autofluores- cence, the emergence of the SHG signal could be noted. By comparing I2PEF images with the structural motifs observed by the confocal Raman imaging system, the morphological similarity of the acquired images was quite evident. Any change in the I2PEF spectra reflects alterations in the chem- ical composition of enamel. These findings may provide an important basis for potentially valuable applications of pho- tonic tools in the clinical diagnosis of tooth pathological con- ditions, besides exposing the fundamental role of organic matrix in enamel integrity and reparation.

Nitrogen-vacancy centers in diamonds possess an electronic spin resonance that strongly depends on temperature, which makes them efficient temperature sensors with sensitivity down to a few mK/√Hz. However, the high thermal conductivity of the host diamond may strongly damp any temperature variations, leading to invasive measurements when probing local temperature distributions. In the view of determining possible and optimal con gurations for diamond-based wide- eld thermal imaging, here, we investigate both experimentally and numeri- cally the effect of the presence of diamonds on microscale temperature distributions. Three geometrical con gurations are studied: a bulk diamond substrate, a thin diamond layer bonded on quartz, and diamond nanoparticles dispersed on quartz. We show that the use of bulk diamond substrates for thermal imaging is highly invasive in the sense that it prevents any substantial temperature increase. Conversely, thin diamond layers partly solve this issue and could provide a possible alternative for microscale thermal imaging. Dispersions of diamond nanoparticles throughout the sample appear as the most relevant approach as they do not affect the temperature distribution, although NV centers in nanodiamonds yield lower temperature sensitivities than bulk diamonds.

Chronic kidney disease (CKD) is characterized by a gradual decline in renal function that progresses toward end-stage renal disease (ESRD). Podocytes are highly specialized glomerular epithelial cells, which form with the glomerular basement membrane (GBM) and capillary endothelium, the glomerular filtration barrier (GFB). GBM is an extracellular matrix (ECM) that acts as a mechanical support and provides biophysical signals that control normal podocytes behavior in the process of glomerular filtration. Thus the modulus of elasticity E or stiffness of “ECM” represents an essential characteristic that controls podocyte functions. The biophysical properties of hydrolyzed Polyacrylamide (PAAm) gels resemble to in vivo ECM and thus provide an opportunity to be applied as ECM-like membranes to study cellular behaviors. Therefore, hydrolyzed PAAm hydrogels were investigated for their potential use as new ECM-like constructs to engineer a basement membrane that form with cultured human podocytes a functional glomerular-like filtration barrier. Such ECM-like polyacrylamide hydrogel construct will provide the unique opportunity of understanding in an in vivo-like setting podocyte cells biological responses by controlling the physical properties of the PAAm membranes. In this work, several PAAm hydrogel layers were prepared by changing the crosslinker concentration. The macromolecular microstructure and stiffness were evaluated by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) techniques respectively. Accordingly, the mechanical properties and the polymeric network porosity can be effectively controlled by modulating the crosslinker concentration as well as the swelling degree. Moreover, modulating gel stiffness significantly influenced podocyte behavior including morphology, actin cytoskeleton reorganization. In conclusion, podocytes response to the variation of the mechanical properties of the membranes correlated with the hydrogels stiffness. This work addresses the complexity of podocytes behavior which will further enhance our knowledge to develop a kidney-on-chip model much needed to study kidney function in both health and disease states.