Search Results (83)

The detection and assessment of atherosclerosis and cardiovascular calcification can inform risk stratification and therapies to reduce cardiovascular morbidity and mortality. In this review, we provide an overview of current and emerging imaging techniques for assessing atherosclerosis and cardiovascular calcification in animal models. Traditional imaging modalities, such as computed tomography (CT) and magnetic resonance imaging (MRI), offer non-invasive approaches of visualizing atherosclerotic calcification in vivo; integration of these techniques with positron emission tomography (PET) imaging adds molecular imaging capabilities, such as detection of metabolically active microcalcifications with ¹⁸F-sodium fluoride. Photoacoustic imaging provides high contrast that enables in vivo evaluation of plaque composition, yet this method is limited by optical penetration depth. Light-sheet fluorescence microscopy provides high-resolution, three-dimensional imaging of cardiovascular structures and has been used for ex vivo assessment of atherosclerotic calcification, but its limited tissue penetration and requisite complex sample preparation preclude its use in vivo to evaluate cardiac tissue. Overall, with these evolving imaging tools, our understanding of cardiovascular calcification development in animal models is improving, and the combination of traditional imaging techniques with emerging molecular imaging modalities will enhance our ability to investigate therapeutic strategies for atherosclerotic calcification. Full article

Photoacoustic imaging has emerged as a promising modality for medical imaging since its introduction. Photoacoustic microscopy (PAM), which is based on the photoacoustic effect, combines the advantages of both optical and acoustic imaging modalities. PAM facilitates high-sensitivity, high-resolution, non-contact, and non-invasive imaging by employing optical absorption as its primary contrast mechanism. The ability of PAM to specifically image parameters such as blood oxygenation and melanin content makes it a valuable addition to the suite of modern biomedical imaging techniques. This review aims to provide a comprehensive overview of the diverse technical approaches and methods employed by researchers to enhance the resolution of photoacoustic microscopy. Firstly, the fundamental principles of the photoacoustic effect and photoacoustic imaging will be presented. Subsequently, resolution enhancement methods for both acoustic-resolution photoacoustic microscopy (AR-PAM) and optical-resolution photoacoustic microscopy (OR-PAM) will be discussed independently. Finally, the aforementioned resolution enhancement methods for photoacoustic microscopy will be critically evaluated, and the current challenges and future prospects of this technology will be summarized. Full article

Aim: To compare shock wave-enhanced emission photoacoustic streaming (SWEEPS) with sonic- and ultrasonically activated irrigation systems in removing Enterococcus faecalis biofilm from the root canal system. Methodology: Fifty human single-canalled mandibular premolars were included in the study. After access cavity preparation, the root canals were prepared to a standardized size and taper. Then, the entire root surface was covered with two layers of resin, and the root apices were sealed before sterilization. All root canals were inoculated with E. faecalis biofilm, and the samples were incubated aerobically for 2 weeks at 37 °C. Biofilm formation was confirmed by scanning electron microscopy. All samples were randomly divided into five groups (n = 10 each) based on their irrigation activation method as A (no treatment or negative control), B (no irrigation or positive control), C (sonically activated irrigation (SAI)), D (ultrasonically activated irrigation (UAI)), and E (needle irrigation activated by an Er: YAG laser device using a SWEEPS quartz tip (SWEEPS)). Then, dentine chips were retrieved, vortexed, and diluted for colony-forming unit counts. Data were analysed using analysis of variance and post-hoc Tukey tests (α = 5%). Results: All methods could significantly reduce E. faecalis biofilm compared with control so that the UAI, SWEEPS, and SAI groups indicated a 23.54%, 14.89%, and 7.81% biofilm reduction, respectively. UAI demonstrated a significantly more effective reduction of E. faecalis biofilm than SAI (p = 0.004). Conclusions: All irrigation activation methods significantly reduced E. faecalis biofilm, with ultrasonic use being the most effective. Full article

The need for faster and more accessible alternatives to laboratory microscopy is driving many innovations throughout the image and data acquisition chain in the biomedical field. Benchtop microscopes are bulky, lack communications capabilities, and require trained personnel for analysis. New technologies, such as compact 3D-printed devices integrated with the Internet of Things (IoT) for data sharing and cloud computing, as well as automated image processing using deep learning algorithms, can address these limitations and enhance the conventional imaging workflow. This review reports on recent advancements in microscope miniaturization, with a focus on emerging technologies such as photoacoustic microscopy and more established approaches like smartphone-based microscopy. The potential applications of IoT in microscopy are examined in detail. Furthermore, this review discusses the evolution of image processing in microscopy, transitioning from traditional to deep learning methods that facilitate image enhancement and data interpretation. Despite numerous advancements in the field, there is a noticeable lack of studies that holistically address the entire microscopy acquisition chain. This review aims to highlight the potential of IoT and artificial intelligence (AI) in combination with portable microscopy, emphasizing the importance of a comprehensive approach to the microscopy acquisition chain, from portability to image analysis. Full article

In this in vitro study, we aimed to evaluate and compare the antibacterial efficacy of a novel erbium-doped yttrium aluminum garnet laser modality, shock wave enhanced emission of photoacoustic streaming (SWEEPS), ultrasonically activated irrigation (UAI), and single needle irrigation (SNI) against old bacterial biofilm. A two-week-old Enterococcus faecalis biofilm was cultivated on transversal dentinal discs made from the middle third of the roots of single-rooted, single-canal premolars. Biofilm growth was confirmed using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The dentine samples were randomly distributed into three experimental groups and one control group based on the irrigation protocol used: Group 1, SWEEPS; Group 2, UAI; and Group 3, SNI. The root canals were irrigated with a 3% sodium hypochlorite solution. Antibacterial efficacy was evaluated quantitatively through bacterial culture and qualitatively through CLSM and SEM. Both SWEEPS and UAI demonstrated a statistically significant reduction in Enterococcus faecalis colony-forming units (CFUs) (p < 0.001), while SNI did not show a statistically significant reduction (p = 0.553). No significant difference was observed between the efficacy of SWEEPS and UAI (p > 0.05). The SWEEPS and UAI techniques were equally effective in eliminating mature E. faecalis biofilm. Full article

The incorporation of gold nanoparticles (GNPs) into retinal imaging signifies a notable advancement in ophthalmology, offering improved accuracy in diagnosis and patient outcomes. This review explores the synthesis and unique properties of GNPs, highlighting their adjustable surface plasmon resonance, biocompatibility, and excellent optical absorption and scattering abilities. These features make GNPs advantageous contrast agents, enhancing the precision and quality of various imaging modalities, including photoacoustic imaging, optical coherence tomography, and fluorescence imaging. This paper analyzes the unique properties and corresponding mechanisms based on the morphological features of GNPs, highlighting the potential of GNPs in retinal disease diagnosis and management. Given the limitations currently encountered in clinical applications of GNPs, the approaches and strategies to overcome these limitations are also discussed. These findings suggest that the properties and efficacy of GNPs have innovative applications in retinal disease imaging. Full article

Photoacoustic imaging (PAI) is an emerging hybrid imaging modality that combines high-contrast optical imaging with high-spatial-resolution ultrasound imaging. PAI can provide a high spatial resolution and significant imaging depth by utilizing the distinctive spectroscopic characteristics of tissue, which gives it a wide variety of applications in biomedicine and preclinical research. In addition, it is non-ionizing and non-invasive, and photoacoustic (PA) signals are generated by a short-pulse laser under thermal expansion. In this study, we describe the basic principles of PAI, recent advances in research in human and animal tissues, and future perspectives. Full article

To identify the vascular alteration by photodynamic therapy (PDT), the utilization of high-resolution, high-speed, and wide-field photoacoustic microscopy (PAM) has gained enormous interest. The rapid changes in vasculature during PDT treatment and monitoring of tumor tissue activation in the orthotopic pancreatic cancer model have received limited attention in previous studies. Here, a fully two-axes waterproof galvanometer scanner-based photoacoustic microscopy (WGS-PAM) system was developed for in vivo monitoring of dynamic variations in micro blood vessels due to PDT in an orthotopic pancreatic cancer mouse model. The photosensitizer (PS), Chlorin e6 (Ce6), was utilized to activate antitumor reactions in response to the irradiation of a 660 nm light source. Microvasculatures of angiogenesis tissue were visualized on a 40 mm² area using the WGS-PAM system at 30 min intervals for 3 h after the PDT treatment. The decline in vascular intensity was observed at 24.5% along with a 32.4% reduction of the vascular density at 3 h post-PDT by the analysis of PAM images. The anti-vascularization effect was also identified with fluorescent imaging. Moreover, Ce6-PDT increased apoptotic and necrotic markers while decreasing vascular endothelial growth factor (VEGF) expression in MIA PaCa-2 and BxPC-3 pancreatic cancer cell lines. The approach of the WGS-PAM system shows the potential to investigate PDT effects on the mechanism of angiographic dynamics with high-resolution wide-field imaging modalities. Full article

In recent years, there has been a growing interest in plant pigments as readily available nutraceuticals. Photosynthetic pigments, specifically chlorophylls and carotenoids, renowned for their non-toxic antioxidant properties, are increasingly finding applications beyond their health-promoting attributes. Consequently, there is an ongoing need for cost-effective methods of isolation. This study employs a co-precipitation method to synthesize magnetic iron oxide nanoparticles. Scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS) confirms that an aqueous environment and oxidizing conditions yield nanosized iron oxide with particle sizes ranging from 80 to 140 nm. X-ray photoelectron spectroscopy (XPS) spectra indicate the presence of hydrous iron oxide FeO(OH) on the surface of the nanosized iron oxide. The Brunauer–Emmett–Teller (BET) surface area of obtained nanomaterial was 151.4 m² g⁻¹, with total pore volumes of pores 0.25 cm³ g⁻¹ STP. The material, designated as iron oxide nanoparticles (IONPs), serves as an adsorbent for magnetic solid phase extraction (MSPE) and isolation of photosynthetic pigments (chlorophyll a, lutein) from extracts of higher green plants (Mentha piperita L., Urtica dioica L.). Sorption of chlorophyll a onto the nanoparticles is confirmed using UV–vis spectroscopy, Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS), and high-performance liquid chromatography (HPLC). Selective sorption of chlorophyll a requires a minimum of 3 g of IONPs per 12 mg of chlorophyll a, with acetone as the solvent, and is dependent on a storage time of 48 h. Extended contact time of IONPs with the acetone extract, i.e., 72 h, ensures the elimination of remaining components except lutein, with a spectral purity of 98%, recovered with over 90% efficiency. The mechanism of chlorophyll removal using IONPs relies on the interaction of the pigment’s carbonyl (C=O) groups with the adsorbent surface hydroxyl (–OH) groups. Based on molecular dynamics (MD) simulations, it has been proven that the selective adsorption of pigments is also influenced by more favorable dispersion interactions between acetone and chlorophyll in comparison with other solutes. An aqueous environment significantly promotes the removal of pigments; however, it results in a complete loss of selectivity. Full article

Bone tissue engineering using osteoconductive scaffolds holds promise for regeneration, with pearl powder gaining interest for its bioactive qualities. This study used freeze drying to create chitosan (CS) scaffolds with pearl/calcium phosphate (p/CaP) powders, mimicking bone tissue structurally and compositionally. Characterization included scanning electron microscopy (SEM) and mechanical testing. X-ray diffraction (XRD) Fourier-transform infrared–photoacoustic photo-acoustic sampling (FTIR−PAS), and FTIR- attenuated total reflectance (FTIR-ATR) were used to characterize p/CaP. In vitro tests covered degradation, cell activity, and SEM analysis. The scaffolds showed notable compressive strength and modulus enhancements with increasing p/CaP content. Porosity, ranging from 60% to 90%, decreased significantly at higher pearl/CaP ratios. Optimal cell proliferation and differentiation were observed with scaffolds containing up to 30 wt.% p/CaP, with 30 wt.% pearl powder and 30 wt.% p/CaP yielding the best results. In conclusion, pearl/calcium phosphate chitosan (p/CaP_CS) composite scaffolds emerged as promising biomaterials for bone tissue engineering, combining structural mimicry and favourable biological responses. Full article

Photoacoustic microscopy (PAM) is a medical-imaging technique with the merits of high contrast and resolution. Nevertheless, conventional PAM scans specimens in a diameter-by-diameter fashion, resulting in a time-consuming process. Furthermore, deep-learning-based PAM image enhancement necessitates acquiring ground-truth data for training purposes. In this paper, we built an optical-resolution photoacoustic microscopy system and introduced an innovative unsupervised-learning algorithm. First, we enhanced the rotational-scanning method, transitioning from a diameter-by-diameter approach to a sector-by-sector one, significantly reducing imaging time (from 280 s to 109 s). Second, by establishing a metric for unsupervised learning, we eliminated the need for collecting reliable and high-quality ground truth, which is a challenging task in photoacoustic microscopy. A total of 324 pairs of datasets (mouse ears) were collected for unsupervised learning, with 274 for training and 50 for testing. Additionally, carbon-fiber data were sampled for lateral resolution and contrast evaluation, as well as the effective rate evaluation of the algorithm. The enhanced images demonstrated superior performance compared with that of maximum projection, both subjectively and objectively. A 76% improvement in the lateral resolution was observed. The effective rate of the algorithm was measured to be 100%, which was tested on 50 random samples. The technique presented in this paper holds substantial potential for image postprocessing and opens new avenues for unsupervised learning in photoacoustic microscopy. Full article

This paper presents a two-axis AlScN-based water-immersible MEMS mirror fabricated in an 8-inch MEMS process. Compared with other studies, this device has a larger optical aperture 10 mm in diameter. The resonant frequencies of the device are 1011 Hz in air and 342 Hz in water. The scanning angle reaches ±5° and ±2° at resonant frequencies in air and water, respectively. The cavitation phenomenon is observed when the device is operating in water, which leads the device to electrical failure. To address this issue, a device with reduced resonant frequencies—246 Hz and 152 Hz in air and water—is characterized, through which the bubbles can be effectively prohibited. This MEMS mirror could potentially be used in ultrasound and photoacoustic microscopy applications. Full article

Bioinspired nanoparticles have recently been gaining attention as promising multifunctional nanoplatforms for therapeutic applications in cancer, including breast cancer. Here, the efficiency of the chemo-photothermal and photoacoustic properties of hybrid albumin-modified nanoparticles (HSA-NPs) loaded with doxorubicin was evaluated in a three-dimensional breast cancer cell model. The HSA-NPs showed a higher uptake and deeper penetration into breast cancer spheroids than healthy breast cell 3D cultures. Confocal microscopy revealed that, in tumour spheroids incubated with doxorubicin-loaded NPs for 16 h, doxorubicin was mainly localised in the cytoplasm, while a strong signal was detectable at the nuclear level after 24 h, suggesting a time-dependent uptake. To evaluate the cytotoxicity of doxorubicin-loaded NPs, tumour spheroids were treated for up to 96 h with increasing concentrations of NPs, showing marked toxicity only at the highest concentration of doxorubicin. When doxorubicin administration was combined with laser photothermal irradiation, enhanced cytotoxicity was observed at lower concentrations and incubation times. Finally, the photoacoustic properties of doxorubicin-loaded NPs were evaluated in tumour spheroids, showing a detectable signal increasing with NP concentration. Overall, our data show that the combined effect of chemo-photothermal therapy results in a shorter exposure time to doxorubicin and a lower drug dose. Furthermore, owing to the photoacoustic properties of the NPs, this nanoplatform may represent a good candidate for theranostic applications. Full article

Epoxy matrix composites reinforced with high-performance fibers, such as carbon, Kevlar, and glass, exhibit excellent specific stiffness and strength in many mechanical applications. However, these composites are disappointingly non-recyclable and are usually disposed of in landfill sites, with no realistic prospect for biodegradation in a reasonable time. In contrast, moldable composites with carbonized elastomeric matrices developed in the last decades possess attractive mechanical properties in final net-shape products and can also be incinerated or recycled. Many carbon and inorganic fillers have recently been evaluated to adjust the properties of carbonized elastomeric composites. Renewable organic fillers, such as human or animal hair, offer an attractive fibrous material with substantial potential for reinforcing composites with elastomeric matrices. Samples of unidirectional fiber composites (with hair volume fractions up to 7%) and quasi-isotropic short fiber composites (with hair volume fractions up to 20%) of human hair-reinforced nitrile butadiene rubbers (HH-NBRs) were produced in the peroxide-cured and carbonized states. The samples were characterized using scanning electron microscopy (SEM), Raman spectroscopy, and photoacoustic microscopy. Mechanical tests were performed under tension using a miniature universal testing machine. The expected effect of fiber reinforcement on the overall mechanical performance was demonstrated for both cured and carbonized composites. Considerable enhancement of the elastic modulus (up to ten times), ultimate tensile strength (up to three times), and damage tolerance was achieved. The evidence of satisfactory interfacial bonding between hair and rubber was confirmed via SEM imaging of fracture surfaces. The suitability of photoacoustic microscopy was assessed for 3D reconstructions of the fiber sub-system’s spatial distribution and non-destructive testing. Full article

Objectives: This study investigates the efficacy of antimicrobial photodynamic therapy (aPDT) using riboflavin and a blue diode laser (BDL), combined with shock wave-enhanced emission photoacoustic streaming (SWEEPS), against Enterococcus faecalis. Materials and Methods: A total of 48 extracted single-rooted human teeth were used. The root canals were instrumented, sealed at their apices, had the smear layer removed, and then underwent autoclave sterilization. Subsequently, each canal was inoculated with E. faecalis bacterial suspension and allowed to incubate for ten days. After confirming the presence of biofilms through scanning electron microscopy (SEM) in three teeth, the remaining teeth were randomly allocated into nine groups, each containing five teeth: control, 5.25% sodium hypochlorite (NaOCl), BDL, SWEEPS + normal saline, SWEEPS + NaOCl, riboflavin, riboflavin + SWEEPS, riboflavin + BDL, and riboflavin + BDL + SWEEPS. After the treatment, the numbers of colony-forming units (CFUs)/mL were calculated. The data were analysed using one-way ANOVA followed by Tukey’s test for comparisons. Results: All groups, with the exception of the BDL group, exhibited a significant reduction in E. faecalis CFU/mL when compared to the control group (p < 0.001). The difference in CFU/mL value between riboflavin + BDL + SWEEPS and riboflavin + SWEEPS was significant (p = 0.029), whereas there was no significant difference between riboflavin + BDL + SWEEPS and riboflavin + BDL (p = 0.397). Moreover, there was no statistically significant difference between the riboflavin + SWEEPS group and the riboflavin + BDL group (p = 0.893). Conclusions: The results demonstrated that combining the SWEEPS technique with riboflavin as a photosensitizer activated by BDL in aPDT effectively reduced the presence of E. faecalis in root canals. Full article