Biomedical optics express最新文献

Alzheimer's disease (AD) is a neurodegenerative disease characterized by amyloid beta (Aβ)-containing extracellular plaques and tau-containing intracellular neurofibrillary tangles. Reliable and more accessible biomarkers along with associated imaging methods are essential for early diagnosis and to develop effective therapeutic interventions. Described here is an integrated photoacoustic microscopy (PAM) and optical coherence tomography (OCT) dual-modality imaging system for multiple ocular biomarker imaging in an AD mouse model. Anti-Aβ-conjugated Au nanochains (AuNCs) were engineered and administered to the mice to provide molecular contrast of Aβ. The retinal vasculature structure and Aβ deposition in AD mice and wild-type (WT) mice were imaged simultaneously by dual-wavelength PAM. OCT distinguished significant differences in retinal layer thickness between AD and WT animals. With the unique ability of imaging the multiple ocular biomarkers via a coaxial multimodality imaging system, the proposed system provides a new tool for investigating the progression of AD in animal models, which could contribute to preclinical studies of AD.

We present a 2.5-mm-diameter resonant fiber scanning two-photon microendoscope with a 30-mm long forward-viewing rigid probe tip that enables video-rate imaging (20 Hz frame rate) suitable for hand-held imaging of tissues without motion artifacts. Higher-order harmonic oscillation scanning techniques are developed to significantly increase the frame rate compared to prior published fiber scanning microendoscopy designs while maintaining the field-of-view (∼125 µm), the optical resolution (1.2 µm lateral and 10.9 µm axial resolution, full width at half maximum), and the spatial sampling (1250 circumferential pixels per spiral × 20 radial pixels over the diameter; 210 spirals per frame, ∼4 spiral samples per resolvable pixel) compared to a traditional scan using the fundamental resonance. 3D printed mounts were created to reduce the cost and simplify the fabrication for the fiber scanner without compromising performance or stability (<0.3 µm drift over 84 hours). A custom long-wavelength (∼1.08 µm) femtosecond fiber laser is coupled into several meters of fiber to realize a flexible, hand-held device for long-wavelength multiphoton microendoscopy.

The 3D structure of native human skin is fundamental for studying skin health, diseases, wound healing, and for testing the safety of skin care products, as well as personalized treatments for skin conditions. Tissue regeneration, driven by tissue engineering, often involves creating full-thickness skin equivalents (FSE), which are widely used for developing both healthy and diseased skin models. In this study, we utilized human skin cell lines to create FSE. We designed high-resolution 3D scaffolds to support the growth and maturation of these skin models. Additionally, we developed and validated a cost-effective, custom-built system combining fluorescence spectroscopy (FS) and optical coherence tomography (OCT) for non-destructive analysis of the metabolism and morphology of 3D FSEs. This system proved highly sensitive in detecting fluorescence from key metabolic co-enzymes (NADH and FAD) in solutions and cell suspensions, while OCT provided adequate resolution to observe the morphology of FSEs. As a result, both the 3D FSE model and the dual-mode optical system hold significant potential for use in 3D bioprinting of biological tissues, as well as in the development of cosmetics, drugs, and in monitoring their maturation over time.

In vivo confocal microscopy (IVCM) is a widely used technique for imaging the cornea of the eye with a confocal scanning light ophthalmoscope. Cellular resolution and high contrast are achieved without invasive procedures, suiting the study of living humans. However, acquiring useful image data can be challenging due to the incessant motion of the eye, such that images are typically limited by noise and a restricted field of view. These factors affect the degree to which the same cells can be identified and tracked over time. To redress these shortcomings, here we present a data acquisition protocol together with the details of a free, open-source software package written in Matlab. The software package automatically registers and processes IVCM videos to significantly improve contrast, resolution, and field of view. The software also registers scans acquired at progressive time intervals from the same tissue region, producing a time-lapsed video to facilitate visualization and quantification of individual cell dynamics (e.g., motility and dendrite probing). With minimal user intervention, to date, this protocol has been employed to both cross-sectionally and longitudinally assess the dynamics of immune cells in the human corneal epithelium and stroma, using a technique termed functional in vivo confocal microscopy (Fun-IVCM) in 68 eyes from 68 participants. Using the custom software, registration of 'sequence scan' data was successful in 97% of videos acquired from the corneal epithelium and 93% for the corneal stroma. Creation of time-lapsed videos, in which the averages from single videos were registered across time points, was successful in 93% of image series for the epithelium and 75% of image series for the stroma. The reduced success rate for the stroma occurred due to practical difficulties in finding the same tissue between time points, rather than due to errors in image registration. We also present preliminary results showing that the protocol is well suited to in vivo cellular imaging in the retina with adaptive optics scanning laser ophthalmoscopy (AOSLO). Overall, the approach described here substantially improves the efficiency and consistency of time-lapsed video creation to enable non-invasive study of cell dynamics across diverse tissues in the living eye.

In this research, we developed an ultrafast laser system based on a Yb-doped fiber oscillator and Yb:YAG thin-rod amplifier to investigate the efficacy of the laser for the treatment of pigmented lesions. The developed laser exhibited an output power of 22.7 W, center wavelength of 1030 nm, repetition rate of 495 kHz, pulse energy of 45.9 µJ, and pulse duration of 1.56 ps, respectively. For a compact and stable chirped pulse amplification system, a chirped fiber Bragg grating (CFBG) stretcher and a chirped volume Bragg grating (CVBG) compressor, both with fixed dispersion, were used. The dispersion of the total laser systems was precisely compensated by adjusting the length of the passive fiber and utilizing the self-phase modulation effect of the fiber amplifier. The developed ultrafast laser system was then applied in preclinical studies for the treatment of pigmented lesions in a guinea pig model. Three colored squares, each measuring approximately 15 × 15 mm, were treated by scanning a focused beam with varying laser fluences ranging from 0.5 to 2 J/cm², using wavelengths of 515 nm and 1030 nm. The colorimeter measurements, which were performed 1-5 weeks after laser treatment, indicated that the laser was effective in reducing pigment, particularly black and blue pigments at higher fluences. This research represents the first trial of a preclinical study on pigmented lesions using an ultrafast laser system with a pulse duration below 10 ps, shorter than the stress relaxation time of 10 nm melanin granules. The results are meaningful as they offer valuable insights into the effectiveness of ultrafast laser therapy.

Accurate assessment and quantification of neoangiogenesis associated with breast cancer could be potentially used to improve the sensitivity and specificity of non-invasive diagnosis, as well as predict outcomes and monitor treatment effects. In this study, we adapted an emerging technology, namely diffuse correlation tomography (DCT), to image microvascular blood flow in breast tissues and evaluate the potential for discriminating between benign and malignant lesions. A custom-made DCT system was designed for breast blood flow imaging, with both the source-detector array and reconstruction algorithm optimized to ensure precise imaging of breast blood flow. The global features and local features of three-dimensional blood flow images were extracted from the relative blood flow index (rBFI), which was obtained from most of the breasts targeted to the lesion. A total of 37 women with 19 benign and 18 malignant lesions were included in the study. Significant differences between malignant and benign groups were found in 12 image features. Moreover, when selecting the lesion mean relative blood flow index (MrBFI) as a single indicator, the malignant and benign tumors were discriminated with an accuracy of 89.2%. The blood flow features were found to successfully identify malignant and benign tumors, suggesting that DCT, as an alternate functional imaging modality, has the potential to be translated into clinical practice for diagnosis and assessment of breast cancers. There is potential to reduce the need for biopsy of benign lesions by improving the specificity of diagnostic imaging, as well as monitoring response to breast cancer treatment.

To find optimal conditions for performing laser induced refractive index change (LIRIC) in living eyes with both safety and efficacy, we investigated multiphoton excitation scaling of this procedure in hydrogel and excised corneal tissue. Three distinct wavelength modalities were examined: high-repetition-rate (HRR) and low-repetition-rate (LRR) 405 nm systems, as well as 800 nm and 1035 nm systems, whose LIRIC-inducing properties are described for the first time. Of all the systems, LRR 405 nm-LIRIC was able to produce the highest phase shifts at the lowest average laser powers. Relative merits and drawbacks to each modality are discussed as they relate to future efforts towards LIRIC-based refractive error correction in humans.

Bioluminescence tomography (BLT) improves upon commonly-used 2D bioluminescence imaging by reconstructing 3D distributions of bioluminescence activity within biological tissue, allowing tumor localization and volume estimation-critical for cancer therapy development. Conventional model-based BLT is computationally challenging due to the ill-posed nature of the problem and data noise. We introduce a self-supervised hybrid neural network (SHyNN) that integrates the strengths of both conventional model-based methods and machine learning (ML) techniques to address these challenges. The network structure and converging path of SHyNN are designed to mitigate the effects of ill-posedness for achieving accurate and robust solutions. Through simulated and in vivo data on different disease sites, it is demonstrated to outperform the conventional reconstruction approach, particularly under high noise, in tumor localization, volume estimation, and multi-tumor differentiation, highlighting the potential towards quantitative BLT for cancer research.

Cystoscopic data can be used to improve bladder cancer care, but cystoscopic videos are cumbersome to review. Alternatively, cystoscopic video data can be preserved in the form of a 3D bladder reconstruction, which is both informative and convenient to review. Developing algorithms for 3D reconstruction is an iterative process and often requires access to clinical data. Unfortunately, the time and access constraints of the urology clinical workflow can inhibit this technical development. In this manuscript, we present a virtual cystoscopy simulator to enable the creation of realistic and customizable cystoscopy videos through the inclusion of motion blur and bladder debris. The user can induce motion blur at set points in the video by setting the cystoscope speed between 1 and 9 cm/s. We also introduce 12 models of bladder debris particles, each model of which has a different color, shape, or size. The user can add bladder debris to the virtual bladder by specifying which debris models to include, the density of the particles, defining the number of particles in the bladder, and whether debris is stationary or blurred and moving at a user-defined speed. This simulator can be used to generate a large collection of unique and realistic cystoscopy videos with characteristics defined by the user for their specific purpose, thereby assisting the development of novel technologies for clinical implementation.

The Bessel beam (BB) has found widespread adoption in various forms of light-sheet microscopy. However, for one-photon fluorescence, the transverse profile of the beam poses challenges due to the detrimental effect of the sidelobes. Here, we mitigate this issue by using a computer-generated phase element for generating a sidelobe suppressed Bessel beam (SSBB). We then progress to perform a comparison of biological imaging using SSBB to standard BB in a light-sheet geometry. The SSBB peak intensity is more than an order of magnitude higher than the first sidelobe. In contrast to a standard BB light-sheet, an SSBB does not need deconvolution. The SSBB propagates to depths exceeding 400 μm in phantom samples maintaining a transverse size of 5 μm. Finally, we demonstrate the advantage of using an SSBB light-sheet for biological applications by imaging fixed early-stage zebrafish larvae. In comparison to the standard BB, we observe a two-fold increase in contrast-to-noise ratio (CNR) when imaging the labelled cellular eye structures and the notochords. Our results provide an effective approach to generating and using SSBB light-sheets to enhance contrast for one-photon light-sheet microscopy.