A dataset of optical spectra and clinical features acquired on human healthy skin and on skin carcinomas.

Optical spectroscopy is studied to contribute to skin cancer diagnosis. Indeed, optical spectra are modified along cancer progression and provide complementary information (e.g., on metabolism and tissue structure) to clinical examination for surgical guidance [1,2]. The current original dataset is made of autofluorescence and diffuse reflectance spectra acquired in vivo on 131 patients' skin with the SpectroLive device [3,4]. Spatially-resolved spectroscopy measurements were performed using a multi-fiber optic probe featuring 4 distances (0.4-1 mm) between excitation and collection optical fibers: spatial resolution allows spectra acquired at different distances to carry information from different depths in skin tissues. Five types of autofluorescence spectra were acquired using five different wavelength excitations (on the 365-415 nm spectral range) in order to collect information on several skin endogenous fluorophores (e.g., flavins, collagen). A sixth light source (white broadband) was used to acquire diffuse reflectance spectra carrying information about skin scattering properties and skin endogenous absorbers such as melanin and hemoglobin. Patients were proposed to be included into the clinical trial if they were suspected of suffering from actinic keratoses (precancerous skin lesions) or from basal or squamous cell carcinomas: in all cases, complete diagnostics is provided in the dataset. To increase the interest of the dataset and evaluate the dependence of optical spectra (intensity, shape) not only on pathological states but also on healthy skin features (civil age, skin age, gender, phototype, anatomical site), spectra were acquired for all 131 patients on two so-called "reference" skin sites known to rarely suffer from skin cancer: palm of the hand (featuring a thick skin type) and inner wrist (featuring thin skin). Spectra are available in .tab files: first column displays the spectral range on which intensity spectra were recorded (317-788 nm) and each following column provides an intensity spectrum acquired by each spectrometer for a given combination of light source excitation and distance. Each of the 131 folders corresponding to each of the 131 patients contains a .json file providing patients clinical features: gender, civil age, skin age, phototype score and class. All .tab files names include anatomical site and anatomopathological diagnostics of the skin site on which spectra were acquired: codes were defined to match a letter or an acronym to each diagnostic and anatomical site. To ensure quality control, a spectrum was acquired on the same calibration standard before starting spectra acquisition on each patient. It is therefore possible to follow the impact of the acquisition optical chain ageing during the 4.5 years that the patients were included. This dataset can be used by epidemiologists for the characterization of populations affected by skin cancers (gender ratio, mean age, anatomical sites typically affected, etc.); it may also be used by researchers in artificial intelligence to develop innovative methods to process such data and contribute to non-invasive diagnostics of skin cancers whose incidence is steadily increasing.

Terbium-Based AGuIX-Design Nanoparticle to Mediate X-ray-Induced Photodynamic Therapy.

X-ray-induced photodynamic therapy is based on the energy transfer from a nanoscintillator to a photosensitizer molecule, whose activation leads to singlet oxygen and radical species generation, triggering cancer cells to cell death. Herein, we synthesized ultra-small nanoparticle chelated with Terbium (Tb) as a nanoscintillator and 5-(4-carboxyphenyl succinimide ester)-10,15,20-triphenyl porphyrin (P1) as a photosensitizer (AGuIX@Tb-P1). The synthesis was based on the AGuIX@ platform design. AGuIX@Tb-P1 was characterised for its photo-physical and physico-chemical properties. The effect of the nanoparticles was studied using human glioblastoma U-251 MG cells and was compared to treatment with AGuIX@ nanoparticles doped with Gadolinium (Gd) and P1 (AguIX@Gd-P1). We demonstrated that the AGuIX@Tb-P1 design was consistent with X-ray photon energy transfer from Terbium to P1. Both nanoparticles had similar dark cytotoxicity and they were absorbed in a similar rate within the cells. Pre-treated cells exposure to X-rays was related to reactive species production. Using clonogenic assays, establishment of survival curves allowed discrimination of the impact of radiation treatment from X-ray-induced photodynamic effect. We showed that cell growth arrest was increased (35%-increase) when cells were treated with AGuIX@Tb-P1 compared to the nanoparticle doped with Gd.

Source separation approach for the analysis of spatially resolved multiply excited autofluorescence spectra during optical clearing of ex vivo skin.

Spatially resolved multiply excited autofluorescence spectroscopy is a valuable optical biopsy technique to investigate skin UV-visible optical properties in vivo in clinics. However, it provides bulk fluorescence signals from which the individual endogenous fluorophore contributions need to be disentangled. Skin optical clearing allows for increasing tissue transparency, thus providing access to more accurate in-depth information. The aim of the present contribution was to study the time changes in skin spatially resolved and multiply excited autofluorescence spectra during skin optical clearing. The latter spectra were acquired on an ex vivo human skin strip lying on a fluorescent gel substrate during 37 minutes of the optical clearing process of a topically applied sucrose-based solution. A Non Negative Matrix Factorization-based blind source separation approach was proposed to unmix skin tissue intrinsic fluorophore contributions and to analyze the time evolution of this mixing throughout the optical clearing process. This spectral unmixing exploited the multidimensionality of the acquired data, i.e., spectra resolved in five excitation wavelengths, four source-to-detector separations, and eight measurement times. Best fitting results between experimental and estimated spectra were obtained for optimal numbers of 3 and 4 sources. These estimated spectral sources exhibited common identifiable shapes of fluorescence emission spectra related to the fluorescent gel substrate and to known skin intrinsic fluorophores matching namely dermis collagen/elastin and epidermis flavins. The time analysis of the fluorophore contributions allowed us to highlight how the clearing process towards the deepest skin layers impacts skin autofluorescence through time, namely with a strongest contribution to the bulk autofluorescence signal of dermis collagen (respectively epidermis flavins) fluorescence at shortest (respectively longest) excitation wavelengths and longest (respectively shortest) source-to-detector separations.