Optimized perfusion‐based CUBIC protocol for the efficient whole‐body clearing and imaging of rat organs

Whole‐organ and whole‐body optical tissue clearing methods allowing imaging in 3 dimensions are an area of profound research interest. Originally developed to study nervous tissue, they have been successfully applied to all murine organs, yet clearing and imaging of rat peripheral organs is less advanced. Here, a modification of CUBIC clearing protocol is presented. It provides a rapid and simple approach to clear the entire adult rat organism and thus all organs within as little as 4 days. Upgraded perfusion‐based rat CUBIC protocol preserves both anatomical structure of organs and signal from proteinaceous fluorophores, and furthermore is compatible with antibody staining. Finally, it enables also volumetric cells analyses and is tailored for staining of calcium deposits within unsectioned soft tissues.      

Inside Cover: Fiber‐based fluorescence lifetime imaging of recellularization processes on vascular tissue constructs (J. Biophotonics 9/2018)

Tissue autofluorescence provides fluorescence lifetime contrast between acellular tissue and that containing newly seeded cells. Fiber‐based fluorescence lifetime imaging (FLIm) can be used for tracking recellularization of engineered vascular grafts and potential matrix remodeling at large scale, without compromising sample integrity. FLIm cellular contrast was verified in a subset of samples seeded with eGFP‐labelled cells. Results suggests fiberbased FLIm is a suitable tool for monitoring recellularization of engineered tissue nondestructively. Further details can be found in the article by Alba Alfonso‐Garcia, Jeny Shklover, Benjamin E. Sherlock, et al. ( e201700391 ).

     

High‐resolution imaging of fluorescent whole mouse brains using stabilised organic media (sDISCO)

Optical tissue clearing using dibenzyl ether (DBE) or BABB (1 part benzyl alcohol and 2 parts benzyl benzoate) is easy in application and allows deep‐tissue imaging of a wide range of specimens. However, in both substances, optical clearing and storage times of enhanced green fluorescent protein (EGFP)‐expressing specimens are limited due to the continuous formation of peroxides and aldehydes, which severely quench fluorescence. Stabilisation of purified DBE or BABB by addition of the antioxidant propyl gallate efficiently preserves fluorescence signals in EGFP‐expressing samples for more than a year. This enables longer clearing times and improved tissue transparency with higher fluorescence signal intensity. The here introduced clearing protocol termed stabilised DISCO allows to image spines in a whole mouse brain and to detect faint changes in the activity‐dependent expression pattern of tdTomato.      

Inside Cover: Polarimetric imaging of biological tissues based on the indices of polarimetric purity (J. Biophotonics 4/2018)

The cover shows the image enhancement of biological tissues provided by the Indices of Polarimetric Purity (IPPs). By measuring the Mueller matrix of a biological sample, using an imaging polarimeter, the IPPs are calculated. They are polarimetric indicators providing further synthetization of depolarizing samples and leading to enhanced image contrast for some biological structures. Once the IPPs are calculated, a pseudo‐colouring technique is applied for higher visualization. Further details can be found in the article by Albert Van Eeckhout et al. ( e201700189 )

     

Inside Back Cover: In vivo full‐field functional optical hemocytometer (J. Biophotonics 2/2018)

Full‐field functional optical hemocytometer (FFOH), based on the absorption intensity fluctuation modulation (AIFM) effect, is in vivo label‐free image method for capillaries of near‐transparent live biological specimens. FFOH can provide a flow video, flow velocity measurement and RBC count, simultaneously. The zebrafish experimental result shows the potential to study the physiological mechanisms of the blood circulation systems. Further details can be found in the article by Fuli Zhang et al. ( e201700039 )

     

Inside Front Cover: Enhanced volumetric imaging in 2‐photon microscopy via acoustic lens beam shaping (J. Biophotonics 2/2018)

Two‐photon microscopy is the tool of choice for fluorescence imaging of deep tissues with high resolution, but can be limited in three‐dimensional acquisition speed and penetration depth. In this work, these issues are addressed by using an acoustic optofluidic lens capable of ultrafast beam shaping on a pixel basis. Driving the lens with different phase profiles enables high‐speed volumetric imaging, or enhanced signal‐to‐background for deeper penetration. Further details can be found in the article by Simonluca Piazza et al. ( e201700050 )

     

Inside Cover: Three‐dimensional intravital imaging in bone research (J. Biophotonics 12/2019)

This review is aimed at interpreting development and advantages of intravital imaging as an emerging invaluable methodology and summarizing related representative discoveries in bone physiologies and pathologies. It also indicates current limitations, further refinement, and extended application of intravital imaging in bone research. Further details can be found in the article by Yuhao Liu, Quan Yuan, and Shiwen Zhanget ( e201960075 ).

     

Inside Front Cover: Near‐infrared bone densitometry: A feasibility study on distal radius measurement (J. Biophotonics 7/2018)

This study provides a simple method to detect human distal radius bone density based on near infrared (NIR) imaging. The information of bone mineral density can be measured by transluminational optical bone densitometric system. Compared to dual‐energy x‐ray absorptiometry (DXA) results in clinical trial, NIR images show a strong correlation to DXA. Further details can be found in the article by Chun Chung, Yu‐Pin Chen, Tsai‐Hsueh Leu, and Chia‐Wei Sun ( e201700342 ).

     

Back Cover: Joint tagging assisted fluctuation nanoscopy enables fast high‐density super‐resolution imaging (J. Biophotonics 9/2018)

Based on multicolor quantum dots (QDs) labeling, the joint tagging assisted super‐resolution radial fluctuation (JT‐SRRF) nanoscopy achieves high‐fidelity super‐resolution imaging of subcellular microtubules and fast live‐cell parallel tracking of cholera toxin subunit B (CTB) induced lipid clusters spatially distributed below the optical diffraction limit. This method paves the way for fast high‐density parallel tracking, which is especially beneficial for the investigation of the intensive dynamics in live‐cell applications. Further details can be found in the article by Zhiping Zeng, Jing Ma, Peng Xi, and Canhua Xu ( e201800020 ).

     

Front Cover: Photoluminescence intensity ratio of Eu‐conjugated lactates—A simple optical imaging technique for biomarker analysis for critical diseases (J. Biophotonics 5/2018)

Eu³⁺integrated photoluminescence intensity ratio (PLIR) approach for optical detection of lactates in blood serum, plasma and confocal imaging of brain tissues has very high potential for exploitation of this technique in both in vitro monitoring and in vivo bioimaging applications for the detection of biomarkers in various diseases states. This image is diagrammatic representation of fact that the overall PLIR is higher with more lactates conjugated with Eu³⁺ ions. Further details can be found in the article by Tarun Kakkar et al. ( e201700199 ).

     

Inside Back Cover: In vivo monitoring blood‐brain barrier permeability using spectral imaging through optical clearing skull window (J. Biophotonics 4/2019)

Monitoring the blood‐brain barrier (BBB) permeability plays a key role in assessing drug release with high resolution. In this work, with the help of optical clearing skull window, we not only realized non‐invasive BBB opening by photodynamic therapy, but also developed a method based on spectral‐imaging to in vivo dynamically monitor the changes in BBB permeability. Further details can be found in the article by Wei Feng, Chao Zhang, Tingting Yu, et al. ( e201800330 ).

     

Front Cover: Spectrally encoded coherence tomography and reflectometry: Simultaneous en face and cross‐sectional imaging at 2 gigapixels per second (J. Biophotonics 4/2018)

SECTR is a novel multimodal imaging platform for combined volumetric optical coherence tomography (OCT) and en face spectrally encoded reflectometry (SER). The authors demonstrate three‐dimensional motion‐tracking with millisecond temporal and micron spatial resolution using complementary data from OCT and SER, and preliminary algorithms and results showing real‐time image aiming and multi‐volumetric mosaicking for reconstruction of wide‐field composites. The image shows a noninvasively imaged nine‐field mosaic of in vivo human retina and depth‐resolved visualization of tissue microstructures. Further details can be found in the article by Mohamed T. El‐Haddad, Ivan Bozic, and Yuankai K. Tao ( e201700268 )

     

Front Cover: A high‐throughput all‐optical laser‐scanning imaging flow cytometer with biomolecular specificity and subcellular resolution (J. Biophotonics 2/2018)

A new type of high‐throughput imaging flow cytometer (>20 000 cells s^‐1) based upon an all‐optical ultrafast laser‐scanning imaging technique, called free‐space angular‐chirp‐enhanced delay (FACED) is reported. FACED imaging flow cytometers enables high‐throughput visualization of functional morphology of individual cells with subcellular resolution. It critically empowers largescale and deep characterization of single cells and their heterogeneity with high statistical power— an ability to become increasingly critical in single‐cell analysis adopted in a wide range of biomedical and life‐science applications. Further details can be found in the article by Wenwei Yan et al. ( e201700178 )

     

Inside Front Cover: Slide‐free imaging of hematoxylin‐eosin stained whole‐mount tissues using combined third‐harmonic generation and three‐photon fluorescence microscopy (J. Biophotonics 5/2019)

Intraoperative margin assessment is clinically important, especially for tissue conserving surgery like Mohs micrographic surgery in which minimization of the surgical area is crucial. Instead of the complex frozen pathology protocol, slide‐free histopathological imaging of hematoxylin‐eosin stained whole‐mount skin tissues is demonstrated by using nonlinear microscopy, thus facilitating rapid intraoperative assessment of surgical tissues for future applications. Further details can be found in the article by Chi‐Kuang Sun, Chien‐Ting Kao, Ming‐Liang Wei, et al. ( e201800341 ).

     

Inside Cover: Label‐free multi‐parametric imaging of single cells: dual picosecond optoacoustic microscopy (J. Biophotonics 8/2019)

Sub‐picosecond light pulses are used to launch high‐frequency ultrasound in cells. The dual detection of acoustic echoes and of the time‐domain Brillouin scattering allows mapping remotely and in a single run experiment the cell adhesion, thickness, storage modulus and mass density, all with micron resolution. The dual picosecond opto‐acoustic microscope is demonstrated with the multiple imaging of a mitotic macrophage‐like cell. This novel modality is compatible with simultaneous fluorescence imaging. Further details can be found in the article by Liwang Liu, Laurent Plawinski, Marie‐Christine Durrieu, Bertrand Audoin ( e201900045 ).

     

Inside Cover: Multi‐ATOM: Ultrahigh‐throughput single‐cell quantitative phase imaging with subcellular resolution (J. Biophotonics 7/2019)

A new quantitative phase imaging (QPI) modality, coined multi‐ATOM, can now capture and process enormous amount of quantitative phase single‐cell images (>700,000 cells) at a ultrahigh throughput without compromising sub‐cellular resolution. It could empower label‐free single‐cell analysis where large‐scale and cost‐effective screening is necessary. Further details can be found in the article by Kelvin C. M. Lee, Andy K. S. Lau, Anson H. L. Tang, et al. ( e201800479 ).

     

Inside Cover: Noninvasive,high‐speed,near‐infrared imaging of the biomolecular distribution and molecular mechanism of embryonic development in fertilized fish eggs (J. Biophotonics 4/2018)

The biomaterial distribution and its molecular mechanism of embryonic development in Japanese medaka fish were visualized without staining using high‐speed near‐infrared imaging. It was a remarkable achievement to visualize the structures of eyes, lipid bilayer membranes, micelles, and water structural variations at the interface of different substances. Furthermore, insights on lipid metabolism and membrane functions were obtained from the biased distribution of lipoproteins and the presence of unsaturated fatty acids in the egg membrane. Further details can be found in the article by Mika Ishigaki ( e201700115 )

     

Inside Cover: In‐vivo hemodynamic imaging of acute prenatal ethanol exposure in fetal brain by photoacoustic tomography (J. Biophotonics 5/2020)

The figure shows the detailed morphology of vasculature and dynamic changes of the blood vessel diameter and density and the oxygen saturation in the blood vessels in fetal brain after acute prenatal ethanol exposure in the second‐trimester equivalent murine model obtained using a real‐time photoacoustic tomography (PAT) system. Further details can be found in the article by Tianqi Shan, Yuan Zhao, Shixie Jiang, Huabei Jiang ( e201960161 ).

     

Back Cover: Prolonged in vivo functional assessment of the mouse oviduct using optical coherence tomography through a dorsal imaging window (J. Biophotonics 5/2018)

Optical coherence tomography through an implanted dorsal imaging window allows for prolonged in vivo structural and functional assessment of the mouse oviduct (Fallopian tube), including threedimensional structural imaging, quantitative measurements of the smooth muscle contraction, and mapping of cilia beat frequency. This method brings new opportunities for live studies and longitudinal analyses of mouse reproductive events in the native context. Further details can be found in the article by Shang Wang et al. ( e201700316 ).

     

Inside Front Cover: Selective and sensitive Escherichia coli detection based on a T4 bacteriophage‐immobilized multimode microfiber (J. Biophotonics 9/2018)

Sensitive Escherichia coli detection based on a T4 bacteriophageimmobilized multimode microfiber is proposed and demonstrated in this article. Different modes are excited and guided in the microfiber as evanescent field that can interact with surrounding E. coli directly. The change of E. coli concentration and corresponding binding of E. coli on microfiber surface will lead to the shift of optical spectrum, which can be exploited for the application of biosensing. Further details can be found in the article by Yanpeng Li, Hui Ma, Lin Gan, et al. ( e201800012 ).