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.
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 )
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 )
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.
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 )
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 ).
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 )
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 ).
In vivo multiphoton imaging was used to map changes in hepatobiliary metabolism in liver fibrosis (left column) and hepatocellular carcinoma (right column). The top row shows the maps of kinetic rate constant of the uptake and esterase processing while the bottom row shows that of bile canalicular excretion of xenobiotics. Further details can be found in the article by Chih‐Ju Lin, Sheng‐Lin Lee, Wei‐Hsiang Wang, et al. ( e201700338 ).
The picture depicts the different 3d‐printed organs, thorax, lungs, heart and bone. Assembled it is used as an optical phantom of a preterm infant for performing percutaneous optical measurements of the gas content in the lungs. In order to simulate the optical properties of the tissue, the heart and thorax can be filled with liquid phantoms, a mixture of Intralipid and Indian Ink. Further details can be found in the article by Jim Larsson et al. ( e201700097 ).
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.
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 ).
Protein secondary structural alteration in the serum sample as induced by colitis has been demonstrated via the spectral fitting. Using DSS mouse models of acute colitis and IL10‐/‐ for chronic colitis, a significant difference in the integral ratio of Gaussian energy bands representing α‐helix and β‐pleated sheet structures were obtained. Further details can be found in the article by Jitto Titus et al. ( e201700057 ).
Nanoscopy enables breaking down the light diffraction limit and reveals the nanostructures of objects being studied using light. In 2014, three scientists pioneered the development of nanoscopy and won the Nobel Prize in Chemistry. This recognized the achievement of the past twenty years in the field of nanoscopy. However, fluorescent probes used in the field of nanoscopy are still numbered. Here, we review the currently available four categories of probes and existing methods to improve the performance of probes.
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 ).
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 ).
Fluorescence imaging studies of the processes leading to photodynamic inactivation of bacteria have been limited due to the small size of microorganisms as well as by the faint fluorescence of most photosensitizers. A versatile method based on highly‐sensitive fluorescence microscopy is presented which allows to study, in real time, the incorporation of photosensitizers inside S. aureus upon photodynamic action. The method takes advantage of the fluorescence enhancement of phenothiazine and porphyrin photosensitizers upon entering the bacterial cytosol after the cell wall has been compromised. In combination with typical assays, such as the addition of specific enhancers of reactive oxygen species, it is possible to extract mechanistic information about the pathway of photodynamic damage at the single‐cell level. Imaging experiments in deuterated buffer strongly support a Type‐I mechanism for methylene blue and a very minor role of singlet oxygen.
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 ).
Label‐free optical nano‐imaging of dendritic structures and intracellular granules in biological cells is demonstrated using a bright and homogeneous nanometric light source. The optical nanometric light source is excited using a focused electron beam. A zinc oxide (ZnO) luminescent thin film was fabricated by atomic layer deposition (ALD) to produce the nanoscale light source. The ZnO film formed by ALD emitted the bright, homogeneous light, unlike that deposited by another method. The dendritic structures of label‐free macrophage receptor with collagenous structure‐expressing CHO cells were clearly visualized below the diffraction limit. The inner fiber structure was observed with 120 nm spatial resolution. Because the bright homogeneous emission from the ZnO film suppresses the background noise, the signal‐to‐noise ratio (SNR) for the imaging results was greater than 10. The ALD method helps achieve an electron beam excitation assisted microscope with high spatial resolution and high SNR.
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 )
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