Journal of biophotonics最新文献

The work aims to study the latest technical developments in instrumental support of laser Doppler flowmetry (LDF) and fluorescence spectroscopy (FS) methods and to evaluate the possibilities of using wearable LDF and FS devices in clinical practice and space medicine. The paper demonstrates the principle of the implementation of wearable LDF and FS devices, the possibilities of forming distributed analyser systems for simultaneous registration of parameters in several areas of interest, and demonstrates examples of registered signals. Prospects and directions of device application in clinical practice are estimated. For the first time, research was conducted to demonstrate the possibility of using wearable LDF and FS devices to record physiological parameters of astronauts in real time during pre-flight training with exposure to overloads, hypoxia and hypobaria, orthostatic and vestibular effects.

Bacterial persistence is a transient phenotypic state in which a subpopulation of cells survives antibiotic exposure without genetic resistance. These dormant, low-metabolic cells are linked to recurrent infections and reduced antibiotic efficacy. Photodynamic inactivation (PDI), which generates reactive oxygen species (ROS) through photosensitizer activation under visible light, is a promising strategy to counteract persistence. This study evaluated PDI effects on Escherichia coli under amoxicillin and gentamicin pressure, using time-kill assays and MDK₉₉/MDK_99.99 metrics. PDI, optimized with methylene blue (10 μM) and 10 J/cm² light at 660 nm, was applied to antibiotic-exposed cells and progeny. For amoxicillin, PDI reduced MDK99 from > 3 to 2 h; for gentamicin, it suppressed regrowth in progeny and reduced MDK_99.99 from 3 to 2 h. Scanning electron microscopy showed morphological damage consistent with persistence. PDI enhanced antibiotic efficacy and shortened treatment time, supporting further investigation of PDI-antibiotic combinations for chronic infections.

Accurate intraoperative determination of bowel viability remains unresolved, as current assessments are subjective and dye-based methods cannot capture reperfusion dynamics. Laser speckle contrast imaging (LSCI) offers a dye-free, real-time, and repeatable approach for quantifying tissue perfusion. We conducted a two-phase rat study to establish a quantitative threshold and validate its predictive value for ischemic recovery. In Phase 1 (n = 6), ischemia (30-180 min) was induced, and LSCI ratios at 60 min after reperfusion were analyzed. A ratio ≥ 0.8 defined viability, whereas < 0.5 indicated irreversible damage. In Phase 2 (n = 4), this threshold was prospectively tested in a survival model. Segments subjected to ≤ 90 min ischemia recovered, the 120-min case showed delayed but complete recovery, while 150 min led to necrosis. This is the first experimental demonstration that LSCI can predict bowel recovery after reperfusion, providing a novel, objective framework for intraoperative viability assessment.

Although the germicidal effects of UV radiation are well documented, its impact on the germination behavior of individual spores remains poorly understood. This study employed single-spore optical analysis to investigate how UV exposure affects Bacillus thuringiensis (Bt) and Lysinibacillus sphaericus (Ls) spores and their germination. Following 2-10 min of UV treatment, spore viability declined to 76%-16% for Bt and 74%-3.3% for Ls. Increased exposure was associated with reduced CaDPA content, decreased intensity at 1280 cm^-1, and increased band ratios (1243/1257 cm^-1 and 1662/1650 cm^-1), indicating structural alterations in amide III and I regions of proteins due to radiation. UV exposure delayed germination responses to both nutrient and non-nutrient germinants, as evidenced by prolonged lag times, extended CaDPA release, and slower cortex lysis. Furthermore, germination heterogeneity increased among individual spores. Collectively, these findings suggest UV radiation likely impairs germination-related proteins, leading to delayed and desynchronized spore germination.

This study conducted laser-assisted vascular anastomosis experiments using a YAG continuous-wave fiber laser (wavelength: 1064 ± 4 nm, maximum power: 10 W) to investigate the effects of process parameters-including laser power, scanning speed, and defocus distance-on the burst pressure strength of vascular tissue. Thermal damage was evaluated based on the thermal damage parameter (Ω), collagen content, and microstructural characteristics. The results indicate that laser power and defocus distance significantly influence the burst pressure strength, while laser power notably affects the extent of thermal injury. The optimal process parameters were identified as a laser power of 6 W, a scanning speed of 300 mm/s, and a defocus distance of 3 mm. Under these conditions, the burst pressure strength reached 52.58 kPa, with a thermal damage parameter Ω of only 0.0623, meeting the requirements for vascular anastomosis.

Effective osteogenic differentiation of human dental pulp stem cells (hDPSCs) is critical for regenerative applications. This study examined the synergistic effects of 810 nm near-infrared photobiomodulation (PBM) and allogeneic fibrin serum (AFS) on hDPSC differentiation and tissue regeneration. Cells cultured with 10% fetal bovine serum or 5% AFS were irradiated with PBM at 71 or 142 mJ/cm². Osteogenesis was assessed by qRT-PCR, Alizarin Red S staining with semi-quantitative image analysis, and histological evaluation of transplanted constructs in immunocompromised mice. PBM alone transiently suppressed early osteogenic markers on Day 7. By Day 14, combined treatment with AFS and 142 mJ/cm² PBM significantly upregulated ALP, COL1, RUNX2, OCN, and RANKL, and enhanced matrix mineralization. In vivo, 8-week constructs pretreated with PBM and AFS showed organized architecture and early mineralization. These findings support PBM-AFS synergy, potentially involving TGF-β1 signaling, as a promising xeno-free approach for bone and dental tissue regeneration.

Spinal cord injury (SCI) leads to severe functional deficits, underscoring the critical need for new therapies. This study evaluated the efficacy of photobiomodulation (PBM) as an early, noninvasive treatment for induced SCI, using specific parameters (808 nm, 72 J/cm², 100 mW). A total of 15 rats were divided into Control (C), SCI, and PBM groups. Efficacy was determined by an integrated approach, correlating ground reaction force (GRF) with quantitative histological assessment. The PBM group showed a significant reduction of secondary damage (33.3 ± 5.5 vs. 53.9 ± 7.0 in the SCI group; p = 0.0002) and preserved neural structure. This tissue preservation aligns with the GRF analysis, which demonstrated that the PBM group recovered gait patterns similar to the Control group. In conclusion, PBM effectively mitigates necrosis aerea, maintaining tissue integrity, improving functional recovery, and reinforcing the PBM's therapeutic potential as a promising translatable strategy for outcomes after SCI. Further research should include immunostaining of cells and larger samples.

In this paper, we present a comparative study of signal decomposition techniques in multispectral photoacoustic microscopy (MS-PAM) systems that are based on the use of stimulated Raman spectroscopy (SRS). The signal decomposition algorithms leverage the inherent delay between the arrival of two photoacoustic (PA) signals, one from 532 nm and the other from 558 nm. We evaluate four signal decomposition methods: fast Fourier transform (FFT), least squares (LSQ), cross-correlation (XCorr), and a deep learning (DL) approach based on a convolutional neural network (CNN) coupled with an autoencoder architecture. These methods are tested against ground truth PA signals generated separately at 532 and 558 nm wavelengths from the mouse brain. Results show that the FFT method consistently outperforms the others in terms of accuracy, while LSQ, XCorr, and DL's performance exhibits greater variability, especially at longer time delays. Finally, the performance of oxygen saturation estimation is evaluated using the best method (FFT).

Histopathology remains the gold standard for definitive tumor diagnosis after surgical resection; however, its lengthy processing time can delay critical postoperative care. Hyperspectral imaging (HSI) is emerging as a promising label-free technique for rapid biochemical tissue assessment. Here, we present HyperProbe1.1 (HP1.1), an HSI system designed for noninvasive analysis of fresh brain tumor biopsies. In this proof-of-concept study, we applied the HP1.1 system to freshly excised meningioma specimens-the most common primary intracranial tumors. The platform enabled rapid, label-free mapping of metabolic activity and vascular heterogeneity, while spectral unmixing further allowed the quantification of endogenous biomarkers such as cytochrome c oxidase (CCO), hemoglobin derivatives, and lipids, revealing molecular patterns consistent with histopathological tumor grading according to the 2021 WHO classification. These results highlight the feasibility of HSI for rapid biochemical tissue assessment and its potential integration into intraoperative decision-making.

A comprehensive image catalog from an in vitro investigation of teeth with occlusal carious lesions is provided. The aim was to visualize carious lesions using various imaging techniques in order to present different stages of caries progression and to provide reference data for the development and validation of polarization-sensitive optical coherence tomography (PS-OCT) as a non-ionizing diagnostic method for dental caries. The study covers a variety of approaches, bridging the gap from basic histopathological analysis of thin sections to future optical imaging of occlusal carious lesions in vivo. All measurements were performed to support the interpretation and validation of PS-OCT imaging based on the degree of polarization (DOP).