The 4T1 tumor model closely approximates the characteristics of human breast cancer and is widely used in laboratory research. Knowledge of the optical parameters of the tumor is important for choosing the correct parameters for laser treatment. In this paper, optical properties and refraction indices of breast tissue in healthy mice and 4T1-model breast tumor have been measured. Using these measurements, absorption coefficient and reduced scattering coefficient have been reconstructed. A significant decrease in both the scattering and refractive index of tumor tissue has been observed. The change in tissue morphology has induced the change in the slope of the scattering spectrum. Thus, the light penetration depth into tumor has increased by almost 1.5-2 times in the NIR “optical windows.” Raman spectra have shown lower lipid content and higher protein content in tumor. The results may be useful for modeling the distribution of laser radiation in healthy tissues and cancers.

Vascular diseases are a leading cause of death and disability worldwide. Despite having precursor conditions like peripheral arterial disease (PAD), they are often only diagnosed after the onset of strokes or heart attacks. Low-cost, portable, non-invasive, point-of-care (POC) assessment of deep vascular function benefits PAD diagnosis, especially in low-and-middle-income countries. Doppler ultrasound-based blood flow measurements can diagnose PAD, albeit, with limited sensitivity and specificity. To overcome this, here, we propose the first-of-its-kind photoacoustic-and-ultrasound (PAUS) imaging system that integrates a multiwavelength pulsed laser diode (PLD) with a compact ultrasound data acquisition system. The portable PLD-PAUS system was validated for deep tissue imaging using tissue phantoms, and for multispectral photoacoustic imaging using an atherosclerosis mimicking phantom. Further, we demonstrated high-contrast volumetric in-vivo photoacoustic imaging of rodent abdominal vasculature and quantified vessel reactivity due to hypercapnia stimulation. The multiparametric functional and molecular imaging capabilities of the PLD-PAUS system holds promise for POC applications.

Pollution from toxic spores has caused us a lot of problems, because spores are extremely resistant and can survive most disinfectants. Therefore, the detection of spore response to disinfectant is of great significance for the development of effective decontamination strategies. In this work, we investigated the effect of 0.5% sodium hypochlorite on the molecular and morphological properties of single spores of Bacillus subtilis using single-cell techniques. Laser tweezers Raman spectroscopy showed that sodium hypochlorite resulted in Ca 2+-dipicolinic acid release and nucleic acid denaturation. Atomic force microscopy showed that the surface of treated spores changed from rough to smooth, protein shells were degraded at 10 min, and the permeability barrier was destroyed at 15 min. The spore volume decreased gradually over time. Live-cell imaging showed that the germination and growth rates decreased with increasing treatment time. These results provide new insight into the response of spores to sodium hypochlorite.

The suitability of ultraviolet (UV) radiation for the decontamination of a surgical face mask was studied by comparing experiments with ray-tracing optical simulations. The 3D fiber network was constructed from X-ray tomography images of the layered mask structure consisting of polypropylene fibers. Both simulations and optical measurements on reflection and transmission indicated that UV light was able to penetrate even the deepest material regions. The decontamination experiments, carried out using Staphylococcus aureus and MS2 microbes, indicated an over 6 log 10 reduction in viable virus contamination of the inner filtering layer. This was achieved within two minutes at a moderate dosage level of 0.22 J/cm 2. The simulations show that despite radiation reflection from the outer mask layer, a significant dosage enters the actual filtering layer due to multiple refraction and scattering of UV light from the inner fibers. This leads to an effective decontamination of fibers with small external UV dosage.

Light exposure has been proven to significantly impact human health, and as a result, researchers are increasingly exploring its potential benefits and drawbacks. With the advancements in understanding light and the manufacturing of light sources, modern health lighting has become widely utilized in daily life and plays a critical role in the prevention and treatment of various illnesses. The use of light in healthcare is a global trend, and many countries are actively promoting the development and application of relevant scientific research and medical technology. This field has gained worldwide attention and support from scientists and doctors alike. In this review, we examine the application of lighting in human health and recent breakthroughs in light exposure related to pathology, therapeutic strategies, molecular changes, and more. Finally, we also discuss potential future developments and areas of application.

Aging brain undergoes multiple structural and functional changes. These may contribute to an increased risk of neurodegenerative disease (NDD) and other age-related diseases, highlighting the importance of assessing deviations from healthy brain aging trajectory. In this human brain study, 50 healthy adults were investigated by functional near-infrared spectroscopy (fNIRS). A resting state single channel multiwavelength fNIRS was measured from the forehead in a supine position. The subjects were divided into four age groups. A machine learning approach was utilized for age group classification by using support vector machine and random forest learners with nested cross-validation. The results suggest brain aging effects being more distinct in the oldest age group and a difference in the brain aging for the subjects of the in-between groups. Our study shows high potential for the use of fNIRS in the analysis of brain aging.

Composite nanoparticles with a gold core enveloped by cobalt ferrite nanoparticles show potential for enhanced photothermal therapy. Determining the optimal gold-to-cobalt ferrite nanoparticle ratio, dependent on size, is vital for improving treatment efficiency. We address the urgent need for advancing photothermal therapy through utilising combined plasmon-magnetic composites with potential of controlled directional delivery. Our computational modeling and experimental absorption spectra analysis reveal that adjusting the cobalt ferrite nanoparticle content redshifts the plasmon resonance frequency in gold nanoparticles, which is accompanied by increase in the extinction cross-section. As a result, cobalt ferrite nanoparticle absorption dominates. Our experiments on photothermal response in aqueous solutions of composite nanoparticles of various concentrations demonstrate that 100 μg/ml solution yields a significant temperature increase of ~8.2 K and a photothermal conversion efficiency of ~51%. At this concentration, the composite nanoparticles effectively heat the cell culture medium under photothermal conditions, leading to 22% reduction in cell viability.

Gram staining can classify bacterial species into two large groups based on cell wall differences. Our study revealed that within the same Gram group (Gram-positive or Gram-negative), subtle cell wall variations can alter staining outcomes, with the peptidoglycan layer and lipid content significantly influencing this effect. Thus, bacteria within the same group can also be differentiated by their spectra. Using hyperspectral microscopy, we identified six species of intestinal bacteria with 98.1% accuracy. Our study also demonstrated that selecting the right spectral band and background calibration can enhance the model’s robustness and facilitate precise identification of varying sample batches. This method is suitable for analyzing bacterial community pathologies.

Cartilage is frequently used as scaffolds for repairing and reconstructing body surface organs. However, after successful plastic surgery, transplanted cartilage scaffolds often exhibit deformation and absorption over time. To enhance the shapping stability of cartilage scaffolds and improve patients’ satisfaction after reconstructions, we employed the ear folding models in New Zealand rabbit to confirm whether the 1064nm Nd:YAG laser could promote cartilage reshapping. There was an increase in collagen and aromatase (Cyp19) expression within the ear cartilage after laser treatment. Moreover, we have discovered that the Cyp19 inhibitor can suppress the shaping effect of the laser on cartilage, as well as the expression of collagen and Cyp19. The overall findings suggest that treatment with 1064nm Nd:YAG laser irradiation can enhance estrogen levels in local cartilage tissues by upregulating Cyp19 expression in chondrocytes through photobiomodulation, thereby promoting the proliferation and collagen secretion of chondrocytes to improve cartilage reshaping and stability.

Metastatic melanoma is a cancer for which vascularization is not a diagnostic criterion. The aim of this study was to evaluate the applicabilities of laser speckle contrast imaging (LSCI) and contrast enhanced ultrasound (CEUS) in a mouse-model. B16F10 cells were xenografted to C57BL/6 mice. Mice were treated with anti-PD1 or 0.9% NaCl and tumor volume was measured daily. CEUS and LSCI were performed weekly. No difference in tumor growth or median survival were observed between treated and no-treaated mice. No significant difference in tumor volume measurement comparing caliper and CEUS was observed. LSCI and CEUS analyses showed a decrease in tumor perfusion in both groups of mice. Although both CEUS and LSCI are useful for measuring tumor volume, LSCI appears to be more robust and effective for monitoring tumor microcirculation. Non-invasive investigations are needed to better predict tumor vascularization: CEUS and LSCI have a good applicability in a mice model.

A novel composite wound dressing hydrogel by incorporating single-walled carbon nanotubes and indocyanine green into a dual-crosslinked hydrogel through Schiff base reaction was developed. The objective was to prevent wound infection and enhance the thermal effect induced by laser energy. The hydrogel matrix was constructed using oxidized gelatin, pre-crosslinked with calcium ions, along with carboxymethyl chitosan, crosslinked via Schiff base reaction. Optimization of the blank hydrogel’s gelation time, swelling index, degradation rate, and mechanical properties was achieved by adding 0.1% SWCNT and 0.1% ICG. Among them, the SWCNT-loaded hydrogel BCG-SWCNT exhibited superior performance overall: a gelation time of 102 seconds; a swelling index above 30 after equilibrium swelling; a degradation rate of 100.5% on the seventh day; and a compressive modulus of 8.8 KPa. It displayed significant inhibition against methicillin-resistant Staphylococcus aureus infection in wounds. When combined with laser energy usage, the composite hydrogel demonstrated excellent pro-healing activity in rats.

5-Aminolevulinic (5-ALA) acid photodynamic therapy (PDT) is a treatment for actinic keratosis and has been studied as a treatment for non-invasive cutaneous squamous cell carcinoma (cSCC). PDT induces apoptosis and necrosis in actinic keratosis and cSCC. 5-ALA blue light PDT may modulate gene expression and pathways in surviving cells. In this study, differential gene expression and pathway analysis of cSCC and human dermal fibroblasts were compared before and after 5-ALA blue light PDT using RNA-Sequencing. No genes were differentially expressed after correcting for multiple testing (FDR <0.05). As a result, transcription factor, gene enrichment, and pathway analysis were performed with genes identified before multiple testing (p<0.05). Pathways associated with proliferation and carcinogenesis were downregulated. These findings using 5-ALA blue light PDT are similar to previously published studies using methyl-aminolevulinic and red light protocols, indicating that surviving residual cells may undergo changes consistent with a less aggressive cancerous phenotype.

We demonstrate an automated two-step tumor segmentation method leveraging color information from brightfield images of fresh core needle biopsies of breast tissue. Three different color spaces (HSV, CIELAB, YCbCr) were explored for the segmentation task. By leveraging white-light and green-light images, we identified two different types of color transformations that could separate adipose from benign and tumor or cancerous tissue. We leveraged these two distinct color transformation methods in a two-step process where adipose tissue segmentation was followed by benign tissue segmentation thereby isolating the malignant region of the biopsy. Our tumor segmentation algorithm and imaging probe could highlight suspicious regions on unprocessed biopsy tissue to guide selection of areas most similar to malignant tissues for tissue pathology whether it be formalin fixed or frozen sections, expedite tissue selection for molecular testing, detect positive tumor margins, or serve an alternative to tissue pathology, in countries where these services are lacking.