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Background and Objectives The study presents a noninvasive, real‐time monitoring technique for the cross‐sectional imaging of the laser‐tissue soldering process with a swept‐source optical coherence tomography (SSOCT) system. The study also aims at performing a comparative study of the laser‐tissue soldering (LTS) process using optimized compositions of albumin as solder biomaterials. Study Design/Materials and Methods The experimental study was conducted both ex vivo and in vivo to assess the superiority of the LTS process over conventional methods using a noninvasive imaging tool. In our attempt to combine the two techniques into one diagnostic tool, we have used the SSOCT system for a thoroughgoing investigation of the process in real‐time. Laser‐assisted tissue soldering was performed using a pulsed near‐infrared (NIR) laser with a central wavelength of 980 nm, an output power of 5 W, and beam diameter (1/e 2) of 6 mm. Here, the SSOCT system has been utilized to observe and analyze the transitions taking place in real‐time without disrupting the process. For the comparative study, we have used serum albumin in a 70% w/v concentration and albumin‐PEG conjugate in a 6:1 ratio as soldering materials. Different stages of the laser interaction process were monitored with OCT B‐scans of the incision area. Also, the basis of biomaterial‐tissue interaction was studied with the help of Fourier‐transform infrared spectroscopy (FTIR) analysis of the soldering materials. Results FTIR spectrum alludes to the fact that the intertwining of the soldering biomaterial with tissue collagen creates adhesion. Biomaterial serum albumin with 70% w/v concentration as soldering material demonstrates complete sealing of tissue at the incision with 3 minutes of laser irradiation. SSOCT B‐scans have been useful in imaging the incision noninvasively at different stages. Conclusion Both ex vivo and in vivo demonstration of the LTS process were presented with a clinical resemblance. OCT can be of great value to determine the wound contraction in case of incisional wounds or sealed wounds produced by the LTS procedure. Also, volumetric measurements of percentage reduction in wound area can be done with OCT. SSOCT system can be a potential imaging modality for real‐time noninvasive imaging of surgical procedures like LTS. Lasers Surg. Med. © 2021 Wiley Periodicals LLC

We present a non-invasive study of the zebrafish brain to understand the vasculature and changing cellular dynamics in the cerebral stroke model using swept-source optical coherence tomography/angiography (SSOCT/A). An ischemic stroke is caused by reduced or obstructed blood supply in the brain, eventually leading to cell death due to insufficient oxygen and nutrient levels. The aberrant/anomalous blood flow characteristics in ischemic stroke are analyzed by phase variance and the doppler method using SSOCT. The subsequent cell mortality is monitored using the speckle-contrast technique of SSOCT. The SSOCT technique for disease surveillance provides fast acquisition time, reduced motion artifacts, label-free visualization, and non-invasive examination.

Monte Carlo simulations are an elementary approach towards modeling light propagation in tissues. The detection of subsurface temperature in tissues during laser mediated therapies and microsurgeries is crucial for estimating associated thermal damage. MC simulation provides with the possibility to optimize the process. The approach has been used to model light propagation, associated energy deposition, and the temperature distribution inside the tissue. Understanding the extent of laser light transmittance and heat distribution within the tissue is crucial for minimizing damage to the adjacent biological tissues. The total photon weight absorbed estimates the total heat distribution within the volume. A three-layer heterogeneous tissue was specified consisting of only the epidermis, dermis, and the subcutaneous fat tissue. The hop, drop, and spin trail of photons depends on the optical properties of these layers. The energy deposition and temperature distribution estimation are obtained by the MC simulation method. A real-time measurement of the temperature profile was also performed. The experimental results were in close congruence with the simulation result. The simulation results show good reproducibility of the real temperature distribution. Monte Carlo method can, thereby, be used in estimation and optimization laser induced processes.

The current study presents a method based on Optical Coherence Tomography (OCT) for non-destructive, real-time analysis and portrayal of immobilization efficacy for lipase on a natural matrix namely, eggshell. Subsequently, qualitative biochemical reaction kinetics of immobilized lipase was also studied. Successful immobilization of lipase on eggshell was confirmed by the presence of a clear peak in 'A' scan of OCT image. From immobilization kinetics it is clearly observed that the thickness of the highest peak of the A-scan increases significantly and peak intensity saturated after 90 min of incubation. Hydrolysis of oil using immobilized lipase indicated that the release of free fatty acids increased up to 8 h during reaction and the result was in accordance with the 'B' scan data of the OCT system. Changes in scattering coefficient-based analysis were performed with respect to incubation time to showcase the immobilization process and hydrolysis reaction of lipase. Scanning electron microscope analysis with smoother surface indicated presence of lipase on eggshell matrices, with no further change after oil hydrolysis.