Back Cover: Non‐invasive optical method for real‐time assessment of intracorneal riboflavin concentration and efficacy of corneal cross‐linking (J. Biophotonics 7/2018)

We disclose a theranostic device for performing image‐guided riboflavin/UV‐A corneal cross‐linking. The device determines treatment efficacy by real time monitoring of riboflavin concentration in the corneal stroma. The study shows efficacy of the device in eye bank human donor tissues. Further details can be found in the article by Giuseppe Lombardo et al. ( e201800028 )

     

Distinction between breast cancer cell subtypes using third harmonic generation microscopy

Third Harmonic Generation (THG) microscopy as a non‐invasive, label free imaging methodology, allows linkage of lipid profiles with various breast cancer cells. The collected THG signal arise mostly from the lipid droplets and the membrane lipid bilayer. Quantification of THG signal can accurately distinguish HER2‐positive cells. Further analysis using Fourier transform infrared (FTIR) spectra reveals cancer‐specific profiles, correlating lipid raft‐corresponding spectra to THG signal, associating thus THG to chemical information.

THG imaging of a cancer cell.     

Inside Front Cover: Combining hyperspectral imaging and chemometrics to assess and interpret the effects of environmental stressors on zebrafish eye images at tissue level (J. Biophotonics 3/2018)

Raman images were used to study the effect of the contaminant chlorpyriphos‐oxon on zebrafish eye samples. Multivariate Curve Resolution‐Alternating Least Squares (MCR‐ALS) was used to obtain the distribution maps and spectral signatures of biological components present in the images analyzed. The use of MCRALS spectral signatures as starting information for Partial Least Squares‐Discriminant Analysis allowed statistical assessment of the effect of the contaminant at a specific tissue level. Further details can be found in the article by Víctor Olmos et al. ( e201700089 ).

     

Inside Cover: Internalization kinetics and cytoplasmic localization of functionalized diatomite nanoparticles in cancer cells by Raman imaging (J. Biophotonics 4/2018)

The internalization kinetics and intracellular spatial distribution of functionalized diatomite nanoparticles in human lung epidermoid carcinoma cell line have been investigated by confocal fluorescence and Raman microscopy. In this context, Raman imaging due to its non‐destructive, chemically selective and label‐free working principle provides evidence that the nanovectors are internalized and co‐localize with lipid environments, suggesting an endocytic internalisation route. Nanoparticle uptakes and intracellular persistence are observed up to 72 hours, without damage to cell viability or morphology. Further details can be found in the article by Stefano Managò et al. ( e201700207 )

     

Front Cover: Dual‐wavelength hybrid optoacoustic‐ultrasound biomicroscopy for functional imaging of large‐scale cerebral vascular networks (J. Biophotonics 9/2018)

We present a hybrid dual‐wavelength optoacoustic and ultrasound bio‐microscope capable of rapid transcranial visualization of morphology and oxygenation status of large‐scale cerebral vascular networks. Imaging of entire cortical vasculature in mice is achieved with single capillary resolution and complemented by simultaneously acquired pulse‐echo ultrasound microscopy scans of the mouse skull. The new approach holds potential to facilitate studies into neurological and vascular abnormalities of the brain. Further details can be found in the article by Johannes Rebling, Héctor Estrada, Sven Gottschalk, et al. ( e201800057 ).

     

Inside Back Cover: The conformation of bovine serum albumin adsorbed to the surface of single all‐dielectric nanoparticles following light‐induced heating (J. Biophotonics 7/2018)

Germanium vs Silicon: All‐dielectric nanoparticles provides the heat resistance for proteins under light‐induced heating. Further details can be found in the article by Andrei A. Krasilin et al. ( e201700322 )

     

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 ).

     

Front Cover: A theoretical‐experimental methodology for assessing the sensitivity of biomedical spectral imaging platforms,assays, and analysis methods (J. Biophotonics 1/2018)

A hyperspectral image data cube acquired from HEK‐293 cells labeled with cytoplasmic and nuclear stains: Calcein Green and NucBlu. The top view (XY plane) displays three spectrally unmixed channels for cellular autofluorescence (red), Calcein Green (green), and NucBlue (blue). The Z axis shows spectral information, from low to high wavelength. The article by Leavesley and colleagues describes an approach for calculating the sensitivity of spectral imaging assays for detecting a fluorescence signature within a mix of other signatures or autofluorescence. Further details can be found in the article by Silas J. Leavesley et al. ( e201600227 ).

     

Fiber probe for nonlinear imaging applications

Over the past years it had been demonstrated that multimodal imaging combining the nonlinear modalities coherent anti‐Stokes Raman scattering (CARS), two‐photon excited auto‐fluorescence (TPEF) and second harmonic generation (SHG) show a great potential for tissue diagnosis and tumor identification. To extend the applicability of this multimodal imaging approach for in‐vivo tissue screening of difficult to access body regions the development of suitable fiber optic probes is required. Here we report about a novel CARS imaging fiber probe consisting of 10,000 coherent light guiding elements preserving the spatial relationship between the entrance and the output of the fiber. Therefore the scanning procedure can be shifted from the distal to the proximal end of the fiber probe and no moving parts or driving current are required to realize in‐vivo CARS endoscopy.

Back scattered CARS image of rabbit aorta with plaques (white) using a laser scanning microscope and an imaging fiber.     

Analysis of major elements in pigmented melanocytic chicken skin using laser‐induced breakdown spectroscopy

The concentration difference of major elements in melanocytic skin with respect to pigmentation level is analysed by laser‐induced breakdown spectroscopy (LIBS) to investigate the applicability of LIBS as an in situ feedback tool for selective and complete laser removal of melanocytic skin tissue like nevus. The skin of black silkie chicken which had a characteristic darkly pigmented perifollicular skin surrounded by lightly pigmented extrafollicular skin was used as the sample. The results showed higher LIBS signal intensities of Ca²⁺ and Mg²⁺ but lower intensities of Na⁺, Cl^– and K⁺ in the perifollicular skin than in the extrafollicular skin, which demonstrated the feasibility to use LIBS as a reliable method to distinguish skin tissues with difference in pigmentation level.

Plasma emission of biochemical elements generated with a laser irradiation on melanocytic skin lesion.     

Dynamic single gold nanoparticle visualization by clinical intracoronary optical coherence tomography

The potential use of Gold Nanoparticles (GNPs) as contrast agents for clinical intracoronary frequency domain Optical Coherence Tomography (OCT) is here explored. The OCT contrast enhancement caused by GNPs of different sizes and morphologies has been systematically investigated and correlated with their optical properties. Among the different GNPs commercially available with plasmon resonances close to the operating wavelength of intracoronary OCT (1.3 µm), Gold Nanoshells (GNSs) have provided the best OCT contrast due to their largest scattering cross section at this wavelength. Clinical intracoronary OCT catheters are here demonstrated to be capable of three dimensional visualization and real‐time tracking of individual GNSs. Results here included open an avenue to novel application of intravascular clinical OCT in combination with GNPs, such as real time evaluation of intravascular obstructions or pressure gradients.

     

A compact fiber‐optic probe‐based singlet oxygen luminescence detection system

This paper presents a novel compact fiberoptic based singlet oxygen near‐infrared luminescence probe coupled to an InGaAs/InP single photon avalanche diode (SPAD) detector. Patterned time gating of the single‐photon detector is used to limit unwanted dark counts and eliminate the strong photosensitizer luminescence background. Singlet oxygen luminescence detection at 1270 nm is confirmed through spectral filtering and lifetime fitting for Rose Bengal in water, and Photofrin in methanol as model photosensitizers. The overall performance, measured by the signal‐to‐noise ratio, improves by a factor of 50 over a previous system that used a fiberoptic‐coupled superconducting nanowire single‐photon detector. The effect of adding light scattering to the photosensitizer is also examined as a first step towards applications in tissue in vivo.

     

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 ).

     

A method to study the hemodynamics of chicken embryo's aortic arches using optical coherence tomography

Congenital cardiovascular defects are the leading cause of birth defect related death. It has been hypothesized that fluid mechanical forces of embryonic blood flow affect cardiovascular development and play a role in congenital malformations. Studies in small animal embryos can improve our understanding of congenital malformations and can lead to better treatment. We present a feasibility study in which high‐resolution optical coherence tomography (OCT) and computational fluid dynamics (CFD) are combined to provide quantitative analysis of the embryonic flow mechanics and the associated anatomy in a small animal model.

     

Cancer cell identification by bi‐color ZnO and TiO2 nanowires

Semiconductor nanocomposites provide advantages beyond the capability of typical fluorescent materials for cancer detection. In this work, nanowire‐based probes with dual color channels are employed to demonstrate the capacity of cancer cell detection. Purple emitting ZnO/antibody probes are applied to detect cancer cells and meanwhile TiO₂/antibody probes with green light emission are applied to identify normal fibroblast cells. A series of quantitative analyses are conducted to verify the correlation between the concentrations of ZnO and TiO₂ probes, cell numbers, and peak intensities of the PL spectra. The results provide a quantitative reference for developing nanowire‐based cancel cell probes.

     

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 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: In‐vitro analysis of early calcification in aortic valvular interstitial cells using Laser‐Induced Breakdown Spectroscopy (LIBS) (J. Biophotonics 1/2018)

Quantitative laser‐induced breakdown spectroscopy (LIBS) is successfully used for in‐vitro analysis of early stage calcification in aortic valvular interstitial cells (VICs). LIBS results indicate 5‐fold improvement in the detection limit of calcium deposition in VICs over cell histology techniques involving staining and colorimetric calcium assays. These results can establish LIBS at the forefront of early detection of calcification in VICs for pathological studies on Calcific Aortic Valve Disease (CAVD). Further details can be found in the article by Seyyed Ali Davari et al. ( e201600288 ).

     

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 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 )