In this work, we present a fast and flexible Mie-scattering python library: PyMieSim. This software allows the end-user to emulate the light interaction of a complete optical system composed of a light source, a scatterer, and a detector and to, subsequently, compute the optical properties of such a system. PyMieSim also lets the user define a range for the optical system attributes and observe the properties to be evaluated within those ranges. Such a tool has applications in many fields, such as optical imaging, flux cytometry, or particle sizing.

Current methods of photodynamic therapy dosimetry are limited in their spatial and temporal resolutions. To address this, we have designed a system that combines therapeutic illumination with both fluorescence and spatial frequency domain imaging (SFDI). Fluorescence imaging during treatment provides information on the photosensitizer distribution and photobleaching rate while SFDI allows for the approximation of fluence, oxygenation, and tissue-corrected photosensitizer concentrations, but requires the treatment be paused. To minimize these interruptions, the single snapshot of optical properties approach was used which requires only a single image frame. A prototype of the system has been built and validated using calibrated phantoms.

In an effort to better understand the functioning of the brain, a new two-photon imaging modality being developed by our group aims to achieve unprecedented imaging speeds at up to 100 kHz. The high powers required for facilitating the same pose the risk of brain heating beyond established thermal limits. This work explores various theoretical boundary conditions for evaluating the impact on resulting spatiotemporal thermal distribution for an input parameter space at 1035nm excitation wavelength using an MC-FDM coupled numerical model with an aim of further paving way towards devising cooling strategies for deep brain imaging.

Laser interactions with cells and tissues play an important role in many areas of biomedical science, providing both the tools to interrogate structure and function of biological systems and the means to affect its properties either through laser surgery or through more gentle effects of low-level laser therapy. While the vast majority of reports can be described using classical light interaction with molecules through absorption and scattering, the quantum nature of light and molecular systems, which are being affected by light, should play a certain role in defining mechanisms of such interactions potentially leading to unusual, non-classical behavior. In this report, I will evaluate our recent results on laser interactions with biological systems at different levels of organization to understand and, possibly, predict quantum behavior of the system upon excitation for coherent laser sources.

Through the induction of a fast thermal gradient, short pulses of infrared light provide a label-free method to stimulate and inhibit action potentials in neurons, but the biophysical effects that underlie this phenomenon are poorly understood. To understand this phenomenon, a computational model of metabolic rates and coenzyme binding dynamics in response to infrared light exposure was developed to investigate the effects of infrared light on cellular metabolism. The resulting model will facilitate our understanding of infrared neural stimulation to accelerate the development of infrared-light technologies which provide a noninvasive, nongenetic, and reversible method to stimulate or inhibit nerve activity.

Previous research indicates that the cytoskeleton microtubules (MT) have resonance frequencies in the radiofrequency (RF) range. In this study, cells were labeled with cytoskeletal markers and were exposed to a range of GHz frequencies. Confocal microscopy analysis was performed following exposures to examine effects due to RF exposures to evaluate changes in cell morphology, and on the organization of MT and overall cytoskeletal network. MT are involved in various cellular processes; therefore, it is important to understand RF energy coupling with MT and associated cytoskeletal organization to enable possibilities for RF energy in future development of non-contact MT-based applications.

Several experimental results have indicated interesting chemical properties of melanosome particles (MPs) derived from retinal pigment epithelial (RPE) cells. These properties may lead to changes in optical properties (absorption in particular) as well. Here, we show characterizations of the MPs before and after various perturbations, including temperature elevation, chemical oxidation, and laser exposure. Methods of analysis included protein fixation, fluorescence, fluorescence anisotropy, dynamic light scattering, transmitted electron microscopy, and confocal microscopy. Finally, we show chemical differences between isolated MPs and those in cytoplasm.

A great deal of research has been focused on the study of the dynamics of single cells exposed to short duration, (<1µs) high peak power (~1 MV/m) transient electric fields. Currently, most of this research is limited to the use of traditional fluorescence-based microscopy techniques, which introduce exogenous agents to the culture and are only sensitive to a specific molecular target depending on the dye used. Quantitative phase imaging (QPI) is a coherent imaging modality which uses optical pathlength (OPL) as a label-free contrast mechanism, and has proven highly effective for the study of single-cell dynamics. In this work, we demonstrate how QPI can be used to monitor biophysical properties of cells undergoing pulsed electric field (PEF) exposure. We introduce new QPI image processing methods to monitor the cellular dry mass, refractive index, mass density, and water content of cells from a single snapshot. These parameters are tracked following exposure to a microsecond-duration pulse. We hope QPI will continue to be used for the study of electroporation-induced bioeffects.

Tracheal stenosis or granuloma is one of the most frequent complications after tracheostomy as a result of inflammatory, traumatic and fibrotic responses. Recently, multidisciplinary treatment has been used for tracheal stenosis and granuloma such as bronchoscopy, balloon dilation and tracheal surgeries. However, current treatments have risk of morbidity and may worsen the situation with high recurrence rate. The purpose of this study is to develop a novel combined treatment of photobiomodulation (PBM) and phlorotannin (PT) to prevent stenosis and granuloma formation after tracheal injury. The therapeutic effect of the combined treatment was evaluated on transforming growth factor (TGF)-beta-stimulated human tracheal fibroblasts and the developed tracheostomy rodent models. A 405 nm wavelength light was applied for PBM in a continuous-wave mode after treatment with Ecklonia cava-derived PT. MTT assay and western blot analysis showed that 12 J/cm2 of PBM and 100 µg/ml of PT were hardly cytotoxic (less than 20%). The combined treatment significantly inhibited cell migration and suppressed the expressions of alpha-smooth muscle actin and type-1 collagen via the downregulation of SMAD 2/3 and MAPK signaling pathways. Moreover, the proposed combined treatment showed promoted healing of tracheal fenestration wounds by modulating inflammation and overexpressed fibrotic activities on the developed tracheostomy rodent models. Therefore, the combination of PBM and PT demonstrates therapeutic potential for preventing tracheal stenosis and granuloma after tracheostomy.

For almost 25 years, the lamp-pumped Chromium (Cr3+), Thulium (Tm3+), Holmium (Ho3+) triple doped yttrium aluminum garnet (CTH:YAG or Ho:YAG) laser has been commercialized for ureteroscopic laser lithotripsy (URSL). However, the transient pressure field profile of the vapor bubbles that arise from laser pulses has not been reported. The transient pressure field of different laser pulses provides further insight into understanding stone ablation and retropulsion. The objective of this study is to measure the transient pressure field profile of the vapor bubbles of standard and custom laser modes of a prototype CTH:YAG laser. (Disclaimers: Concept device or technology. Not available for sale. This device is not yet available for sale in the United States).

The successful laser ablation of clinically relevant tissue models by means of picosecond laser pulses is presented. This is a potential alternative to overcome limitations of conventional electrocautery tools in terms of precision and thermal damage. The correlation of high-speed imaging of the process and a histopathological analysis of the post-process tissue morphology enables optimisation of the tissue removal rate whilst avoiding adverse cavitation effects in order to keep the collateral thermal damage to a minimum. Effective tissue removal is presented for the epithelial laser ablation of colonic tissue and the translation of this process towards head and neck surgery and brain surgery is discussed.

The aim of this study was to develop a microfluidic-powered optical platform to real-time monitor microbial biofilm formation at the single-cell level under a precisely controlled laminar flow condition and to rapidly evaluate the cleaning effect of laser irradiation on a mature microbial biofilm. A 405-nm laser light was used to evaluate the cleaning effects on both mature biofilms. The results show that Staphylococcus aureus biofilm was reduced by 80% in population, which was 20% higher than that of Candida albicans biofilm. A further study will be conducted in a poly-microbial biofilm commonly causing urinary tract infections.

Photobiomodulation (PBM) has been investigated for stimulation biological processes including wound healing and pain recovery. Therefore, in this study, the effects of PBM under BL, Visible, and NIR laser irradiations on prostate cancer cells were evaluated to establish safety margins. In in vitro and in vivo studies, BL showed upregulated expression of VEGF, HIF-1α, and EGFR, whereas TGF- β1 was downregulated. These results suggested that BL irradiation can stimulate cancer cell proliferation, angiogenesis, and hypoxia, leading to aggressive tumor growth. These outcomes can provide a safety margin for the response of PBM-related stimulation after laser treatment.

Laser lithotripsy has clinically been implemented to treat urinary stone disease by using a Ho:YAG laser system. Bubble dynamics plays an important role in determining stone ablation efficiency. The current study developed a two-phase opto-thermal model to numerically assess the bubble dynamics during laser irradiation. The simulation involved light propagation, light and water interaction, and multi-phase heat and mass transfer. The simulation was verified by the experimental setup including Ho:YAG lasers, fiber in water, and high-speed camera. Both the numerical simulations and the experimental results showed a good agreement in predicting the effects of laser pulses on the bubble dynamics.

A balloon-integrated diffusing applicator has been developed to treat urethral stenosis. To deliver uniform light, the balloon was inflated by inserting water. However, the air trap in the balloon can cause non-uniform ablation in the tissue due to different thermal boundary conditions between air and water. The current study aims to evaluate optical and thermal effects of the air trap on cylindrical laser treatment of urethral stenosis. Although a siginificant decrease of the air volume in the balloon, at least two deflations were required to entail uniform coagulation in a tubular structure and to avoid the unpredictable optical/thermal effects from the air trap.

The aim of the current study was to investigate the effect of spatial light distribution from flat (FA) and diffusing applicator (DA) on photothermal therapy (PTT) of tumor treatment in in vivo models. Due to cylindrical and wide light distribution, DA yielded uniform thermal coagulation as well as covering the entire tumor region while FA partially ablated the tumor (i.e., two-fold larger). In vivo tests presented that the DA group significantly reduced the tumor volume (i.e., 0.7 cm3), whereas the FA group yielded unpredictable tumor removal and remarkably tumor growth (i.e., 1.6 cm3) after seven-days treatment (Day 7). The proposed DA-assisted PTT can be a feasible way to treat prostate tumor in an effective and safe manner.

The Ho:YAG laser has been the favored lithotripter for the treatment of urinary calculi since shortly after its introduction in the 1990s, because it can fragment all calculi compositions. The objective of this study is to simulate the transient thermal behavior of the lamp-pumped laser rod from preheating to laser operation. The simulation tool used for this study is the Ansys AIM, and the transient thermal behavior of the lamp-pumped laser rod from preheating to laser operation was reported. Optimization of the pumping pulse for the desired laser output pulse is for a future study. (Disclaimers: Concept device or technology. Not available for sale. This device is not yet available for sale in the United States).

In this study, MLA-assisted PTT with power modulation was evaluated to compare treatment efficiency with Flat. Human prostate cancer cell was used for in vivo tests into three groups : control, MLA and Flat. 1064nm laser was irradiated 3 W/ cm2 to 1.5 W/cm2 for 60 s. Histological analysis was used to compare the treatment efficiency of application for MLA and Flat, which showed that the MLA group could covered the entire cancer area compared to Flat. In these results, the proposed MLA-assisted PTT can enhance treatment efficiency with a uniform beam distribution for prostate cancer.

Tissue analysis is pivotal research to determine the pathological properties that occur after the wound healing process. Several staining techniques to understand the morphology of scar tissue are widely used, such as staining with HE (Hematoxylin and Eosin), picrosirius red, and Masson's Trichome. Tissue staining using hematoxylin and eosin has several limitations: labor-intensive, time-consuming, high memory, and cost. Besides that, used a whole slide image to analyze the scar lesion can be more challenging. Hence, we used deep learning to automatically classify and localize scar lesions in the whole slide image based on object instance segmentation. Deep learning trained the patterns from the data representation through a neural network and convolution equations. Deep learning recognized 384 images in less than a minute with 99.89% accuracy. Therefore, the proposed deep learning method can be time- and cost-effective to characterize the pathological feature of scar tissue for the objective histological analysis. In addition to confirming the scar's recognition in the qualitative analysis, the authors also performed a quantitative analysis to obtain information from the scar tissue, such as collagen density from color extraction and collagen directional variance. Segmentation analysis is also used to determine the morphological structure in scar tissue compared to normal tissue. The analysis results can determine various further therapeutic methods to reduce or even eliminate scars on urological tissues in future works.