The ex vivo porcine lung tissue exposure to nicotine-flavour free e-liquid was examined in-depth using confocal Raman micro-spectroscopy. It was found that the lung-related Raman bands and autofluorescence intensities were enhanced after exposure to e-liquid for all depths and treatment time (first and second treatments) due to the optical clearing effect of glycerol and propylene glycol as an OC agent. The nicotine-flavour free e-liquids that contain glycerol and propylene glycol could potentially be used in clinical protocols for lung disease discrimination in-depth using Raman-based in vivo bronchoscopy due to light scattering reduction as an optical clearing agent.

Fatty liver disease, or steatosis, is a pathology characterized by the presence of fat droplets in the cytoplasm of hepatocytes. This common and potentially severe condition can result in liver damage and various health complications. The current gold standard method to assess steatosis involves an invasive biopsy and a subjective anatomopathological analysis. In this study, we introduce a novel non-invasive approach based on near infrared diffuse reflectance spectroscopy. Currently, NIR DRS methods are often use to quantify fat fraction but our method provides a way to quantify a fraction of hepatocytes affected by steatosis and thus can be directly compared to anatomopathological analysis. The results obtained from this method demonstrate a strong correlation with the gold standard.

Corneal crosslinking (CXL) with UVA light is the primary treatment for keratoconus, a disease that affects cornea's stability, transparency and shape. UVA-CXL has limitations in penetration depth and unwanted irradiation on healthy tissue. As an alternative, a near-infrared femtosecond laser was used for targeted corneal crosslinking of fresh pigs’ corneas. Brillouin microscopy was implemented as a non-destructive method to determine the viscoelastic properties, by measuring the Brillouin shift. We compared the Brillouin shifts measured for UVA-CXL and fs-CXL treated corneas. Measurements were also performed on UVA-CXL pure bovine collagen I in order to correlate the changes observed in CXL cornea. An increase in Brillouin shift before and after crosslinking, for both UVA and femtosecond-CXL are measurable. We demonstrate the precision and efficacy of using femtosecond CXL in spatial targeted CXL at depth in corneal tissues.

A characteristic feature of diabetes mellitus is an increase in blood glucose levels and the development of hyperglycemia, which provokes the development of metabolic changes at the level of cells and tissues of the body. The dysfunction of pancreatic beta cells with impaired insulin secretion and a decrease in their mass is the main sign of the development of both types of diabetes. Thus, beta cells are the main target in the development of new therapeutic approaches.

In this work, using a model of pancreatic beta cells (RINm5F), the effect of photosensitizer-free laser-induced singlet oxygen (SO) on the bioenergetics of this type of cells was studied. It was found that laser exposure affects a number of parameters characterizing the bioenergetics of cells: mitochondrial membrane potential, NADH, FAD and ATP levels. The totality of the results obtained may indicate the potential possibility of using laser-induced SO in the regulation of beta cell functions.

In this work, ablation of clinically relevant mammalian brain tissue was demonstrated using 200-fs laser pulses at 205 nm wavelength. The ablated region depth could be controlled by adjusting the pulse energy and pulse spatial separation; using low-energy deep ultraviolet laser pulses allowed for the removal of very fine layers of tissue. Histopathological analysis revealed minimal thermal damage to the tissue regions adjacent to the ablation craters. Optical coherence tomography was used for surface profile measurements of the laser-processed tissue. The presented deep ultraviolet ultrashort laser ablation technique could be utilised in surgical procedures that require precise tissue removal, for example to facilitate more complete resection of tumour margins located close to brain critical structures where use of conventional surgery tools might cause irreparable damage.

Collagen type I is extensively employed in 3D cell culture and tissue engineering.This research investigates the impact of embedded microbeads of different types on the fibrillogenesis process in collagen type I hydrogels. Our findings reveal that the presence of microbeads within the collagen matrix alters the fibrillogenesis dynamics. Specifically, carboxylated fluorescent microbeads accelerate gelation by 3.6 times, while silica microbeads decelerate collagen fibril formation by a factor of 1.9, in comparison to pure collagen hydrogels. These observations suggest that carboxylate microbeads serve as nucleation sites, influencing the binding of early collagen fibrils to the microbeads.

Conventional histopathological methods, being time-consuming and resource-intensive, leave room for improvement with label-free optical techniques. In this study, our novel metasurface-based polarimeter has been verified for imaging of unstained histological tissue blocks and benchmarked against industrially calibrated polarization measurement systems. The novel system is based on a specifically designed metamaterial grating enabling movement/rotation-free characterization of the light polarization state, ensuring reduced measurement noise in the obtained polarimetric data. The demonstrated potential suggests a transformative, affordable, and scalable standalone system, enhancing accessibility for researchers and clinicians in polarization-based biotissue imaging.

During neurooncological surgery the intraoperative visual differentiation of healthy and diseased tissue is often challenging. In our prior work we demonstrated that imaging Mueller polarimetry is a promising tool for both ex- and in-vivo brain tissue differentiation and diagnosis. Apart from the superficial 2D-polarimetric maps of brain fiber tracts that can be generated with IMP, the knowledge of the probing tissue volume is crucial for the estimation of residual tumor thickness and the proximity of underlying fiber tracts. Here, we quantified the penetration depth of a probing light beam by evaluating the polarimetric maps of formalin-fixed (FF) human cerebral corpus callosum sections of different thicknesses measured in reflection, and we extended the analysis to FF gray matter brain sections of different thicknesses. Finally, we evaluated the light penetration depth at different wavelengths. Our findings allow us to define different thresholds of light penetration depth for white and gray brain matter.

This study analyses intraoperative multispectral images taken from 47 brain tumour surgeries to investigate the diagnostic and surgical guidance potential of MSI. The research enrolled patients with various tumour types and introduces a hybrid model, uniting a transformer-coupled convolutional neural network (CNN), tailored for multispectral brain image segmentation. Leveraging MSI, the model was preliminarily assessed on ten meningioma and thirty-three glioma cases, each categorized into seven distinct classes. The model demonstrated a promising overall accuracies of 88.14% for meningioma and 85.64% for glioma. These initial results highlight the potential of the proposed hybrid architecture in multispectral brain image segmentation, laying the foundation for future research to optimize the model's performance with a larger patient cohort.

Spatial light distribution prediction is highly useful but challenging; no imaging method is currently capable of measuring it at different depths. This study introduces a novel technique for fluence quantification within blood vessels through the ratio of photoacoustic fluctuation imaging (PAFI) and ultrasound power Doppler (USPD). However, their direct coupling fails in accurately estimating the fluence due to differences in the Point Spread Functions (PSFs), leading to varying image resolution and amplitude dependence over vessel sizes. To address this, we propose a model-based matrix approach to apply a non-stationary PSF filter to USPD. Validation through 3D simulations and experiments with tissue-mimicking phantoms demonstrates accurate fluence recovery. Results indicate a robust correlation with the Monte Carlo-simulated ground truth, even in unresolved vessels. This direct imaging technique uniquely offers precise measurement of light distribution in ubiquitous blood vessels, showing great potential for clinical applications and quantitative photoacoustic inverse problems.

In spectral-domain optical coherence tomography (SDOCT), traditional spectrometers with a grating and line-scan camera yield nonlinear wavenumber responses, affecting OCT signal sensitivity and resolution. This necessitates post-processing for spectral interferogram remapping, but it's limited in short-wavelength ranges due to uneven pixel frequency spacing.

To overcome these challenges, we introduce a cost-effective, simple linear-wavenumber spectrometer using a dual-prism and reflector setup, significantly enhancing spectral dispersion linearity, vital for ultra-high resolution SDOCT. Our method employs iterative calculations with global stochastic gradient descent for higher-order dispersion linearization. This results in a substantial increase in wavenumber linearity, from 99.9714% to 99.9998% for 80 nm at 850 nm wavelength, and 99.6828% to 99.9861% for 260 nm bandwidth. Our design eliminates resampling needs for up to 260 nm bandwidth, with nonlinearity-induced wavenumber mismatch under one pixel.

This innovation marks a significant advancement in SDOCT spectrometer design, enhancing performance and resolution beyond traditional system limitations.

Over the past few decades, a multitude of optical imaging techniques have emerged. Among them, full-field optical coherence tomography (FF-OCT) has gained significant importance in various biomedical applications. Indeed, FF-OCT stands out as a noninvasive and label-free imaging method capable of generating high-resolution 3D microscopic images of light-scattering biological specimens. However, FF-OCT approach is limited for in-vivo imaging and images from FF-OCT lack the specificity required for accurate diagnosis. Hence, there is a need to have access to in-vivo imaging and to incorporate additional contrast modalities, such as elastography, into the FF-OCT technique. Indeed, the combination of FF-OCT with shear wave elastography enables the quantitative assessment of tissue stiffness at a resolution of a few micrometers. In this context, we present a novel FF-OCT approach that enables single-shot acquisitions, making it well-suited for both in-vivo imaging and transient shear wave elastography.

Throughout the history of medicine, assessing stiffness through palpation has served as an indicator to gauge tissue health. Within our research team, we are advancing an innovative approach for full-field optical elastography, rooted in noise correlation analysis. This method leverages the relationship between the correlation function of a diffuse shear wave field and the time reversal of the shear wave field. By examining the correlation function, we then have access to an estimation of the shear wave speed, directly linked to tissue stiffness. Recent findings using this approach have shown great promise. However, in most cases, only the elasticity is quantified, despite the availability of additional information, such as viscosity, also present in the correlation function. In this paper, we introduce our initial outcomes in integrating noise correlation with artificial intelligence. More specifically, we employ a U-NET-based architecture to process noise correlation data.

Optical coherence elastography (OCE) provides mechanical contrast on the micro-scale and has shown promise in a number of clinical applications. In the majority of OCE methods, local homogeneity is inherently assumed in the mechanical models, which results in low accuracy in complex tissues. Here, we present a novel compression OCE method that exploits tissue heterogeneity to generate mechanical contrast in human breast tissue by mapping the full strain tensor. We used the strain tensor to map mechanical parameters such as Euler angle of principal compression. We also demonstrate a new form of quantitative OCE by mapping local Poisson’s ratio.

Elastography is an emerging imaging technique that has already proved its clinical usefulness with MRI and ultrasound methods. In the last years, elastography methods have also been adapted to optical setups, expending its applications to new possibilities. In this presentation, we propose a generalization of the NCi method to partially coherent mechanical wave field. The method is first validated finite difference simulations and a proof of concept using optical, ultrasound and MRI commercial systems is presented.

Ultrasound waveguiding of light is a recently introduced technique aiding light transport in scattering media, effectively reducing scattering strength. This technique locally, transiently, reversibly modifies the refractive index of the medium, recollecting and guiding some of the scattered photons to increase light intensity in depth. Here we use transient transversal ultrasound light waveguiding to increase the strength of the signal received from fluorescent target hidden behind a 3 mm thick scattering phantom. We use a common linear array transducer and transmission geometry and show waveguiding-induced increase of fluorescence, excited by a pulsed 532 nm light, typical for photoacoustic imaging setting.

The guiding or focusing of light, crucial in many applications, often relies on bulky optical elements that are difficult to place in delicate mediums like biological tissue. In current systems, the optical components are located outside the sample, limiting possibilities due to geometric constraints. Scattering further complicates the control of light within non-homogeneous media, restricting operating beyond 1 mm of depth. A promising solution involves shaped ultrasound to induce refractive index gradients within the tissue, acting as embedded lenses or waveguides. However, existing methods rely on bulky ultrasonic transducers, introducing invasiveness and fixing the ultrasound geometry. The proposed approach uses photoacoustic generation of pressure waves within the medium, allowing light guiding without geometrical constraints. As it is successfully demonstrated in tissue phantoms with different scattering coefficients, this method offers a promising solution in conditions not feasable with traditional external optical elements.