This presentation will report an easy-to-handle, switchable, and safe optical clearing skull window. It not only allow us image cortical vascular structure and function, but also control cortex by laser without craniotomy.

Here, we demonstrated that natural magnetic nanoparticles (nMNP) from magnetotactic bacteria can serve as photoacoustic high-contrast agents for single cell analysis. The main benefits of nMNP include biocompatibility and relatively low laser fluence for photoacoustic detection. These features together with safety of photoacoustics provide potential for clinical translation. Further decoration of nMNP with NIR-absorbing gold nanorods provided hybrid nanoparticles with strong NIR absorption and plasmonic effects for cancer cell theranostics. In studies in vivo, we showed that circulating tumor cells labeled with bioinspired hybrids generated transient ultrasharp photoacoustic resonances as the basis for new super-resolution photoacoustic flow cytometry in vivo.

An anigiosome foot concept, that a source artery makes the different spaces of skin and underlying tissues, was devised for reconstructive plastic surgery. However, this concept is still controversial, in the aspect of the direct relationship between arterial blood flow and micro-perfusion. In this study, we applied a diffuse speckle contrast analysis system which can estimate tissue perfusion onto the healthy foot, to investigate whether the angiosome foot concept is fact or not. Our preliminary results do not fully support the angiosome concept, but we achieved reproducible results from the correlation analysis of low frequency oscillations, and their physiological implication is discussed.

We apply time-domain diffuse correlation spectroscopy (TD DCS) to quantify dynamics in samples with mixed dynamics, containing both static and dynamic scatterers. We demonstrate that standard TD DCS processing is incapable to properly quantify dynamics at short source-detector distances due to the strong influence of the static component. To solve this problem, we introduce a novel model, which allows recovering the autocorrelation decay of the dynamic part properly. We then apply this novel approach in humans in vivo. We recovered the blood flow index of the leg muscle covered by the thin static turbid layer during the cuff occlusion challenge.

Since AIEgens generally have a large Stokes’ shift, which is beneficial for restraining the fluorescence background induced by the STED light, as well as high photobleaching resistance in their nanoaggregate states, which provides the potential for long-term imaging under a STED beam with high power density, they are ideal fluorescent agents for STED nanoscopy. Dynamic mitochondrial visualization was achieved on the nanometer scale. Their moving, fission and fussion of mitochondria was clearly observed with a lateral spatial resolution of 74 nm. Thus, AIEgen based STED nanoscopy holds great potential for many basic biomedical studies of vital activities those require super resolution.

Non-invasive imaging modalities, especially optical coherence tomography (OCT) are capable of providing high resolution structural and functional imaging capabilities for ophthalmic applications. Apart from functional imaging, OCT has also been used to extract functional dynamics within the microvasculature in response to changes in local environment. Cornea is the transparent, avascular layer of the eye that controls the entry of light into the eye and also helps to refract the light onto the retina. Corneal injuries caused by various chemical, physical, and pathological stimuli damages the corneal epithelium, the stroma and the endothelium, thereby hindering its proper functioning. In this paper, we report the first description of studying corneal dynamics using nano sensitive OCT based approach to detect the dynamic/temporal structural changes within the cornea following an alkali injury.

This work is to address the question of how the early valveless embryonic heart pumps blood through investigating the pumping mechanism at a very localized level. With 4D OCT imaging of the cardiodynamics and hemodynamics of the mouse embryonic heart at embryonic day 9.0, we performed quantitative analysis of the causal relationship of the solid and fluid behaviors. This analysis allows us to dissect the detailed relationship between the blood flow and the adjacent cardiac wall movement, providing new insights into the functions of the tubular embryonic heart.

Sound evoked transduction within the sensory epithelia, the organ of Corti, in the mammalian cochlea is a complex system. Vibrometrical studies of cochlear mechanics has revealed important vibration of the cell bodies involving the epithelia. However, difference in vibration pattern of the apical and basal side of the cell has remain uncertain due to low spatial resolution of the system and low reflectivity of the cells. We developed a modified spectral domain optical coherence tomography (SD-OCT) based on a commercial system. Supercontinuum light source, which has a broad wavelength and strong power, is introduced into the system. We present the different pattern between nano-scale vibrations in both sides of outer hair cells, which actively shrink and elongate cycle by cycle in the sound stimulation in vivo.

Pulsatile signals from different tissue depths could be used as a surrogate for diagnosis purpose. However, most imaging devices do not have the ability to provide depth-resolved measurement. OMAG is a non-invasive 3D imaging tool that can image unprecedented detail of capillaries. The pulsatility of different vessels, from arteriole and venue to capillary beds, have been successfully detected by analyzing the OMAG intensity signals at different depths, where capillaries and arterioles showed distinctly different blood flow dynamics. This study could shed some new light on understanding how light travel through tissues, and also establishing foundation on investigating microvascular relationships.

Maternal cigarette smoking is associated with a wide range of abnormalities including intrauterine growth restriction, perinatal mortality and morbidity, placental abruption, and other early childhood disorders. Although several studies have documented lower birth weights, morphological and behavioral changes, not much has been done evaluating the acute changes in brain vasculature due to prenatal exposure to nicotine. This work uses correlation mapping optical coherence angiography to evaluate changes in murine fetal brain vasculature, in utero, minutes after prenatal nicotine exposure. A rapid and significant decrease in vasculature was observed as compared to the sham group.

Our team has recently shown the SNR and depth-sensitivity advantages of using 1064 nm light for diffuse correlation spectroscopy as well as the challenges of commercially available single-photon detectors at this wavelength. We will review two strategies for custom readout integrated circuit designs that simultaneously target lower pixel dead times and lower afterpulsing probabilities. Both designs use macropixels comprising many detectors, each having a programmable hold-off time. We will compare simulated autocorrelations for our detector models and compare predicted performance against commercial InGaAs/InP detectors.

In this study, we measure the Mueller matrix microscopic images of breast ductal carcinoma tissue samples at different progression stages, and calculate the Mueller matrix polar decomposition and transformation parameters to provide quantitative information on the location, density and distribution behavior of the fibrous structures. We analyze the polarization-staining images based on the retardance related Mueller matrix derived parameters using the gray level co-occurrence matrix method. The results demonstrate that the Mueller matrix derived parameters combined with image analyzing methods can be used for label-free detecting and quantitative staging of breast carcinoma tissues, which can be helpful for clinical diagnosis.

The ability of diffuse correlation spectroscopy (DCS) to measure tissue perfusion paves the way for monitoring cerebral blood flow non-invasively. However, during measurements on human forehead, the measured blood flow index (BFi) is susceptible to contamination due to the blood flow in extracerebral tissue. Time domain DCS addresses this problem by selecting photons based on their travel time to obtain BFi at various depths. We have determined the gate start time(s) and width(s) that can lead to optimal sensitivity of BFi to brain blood flow during actual measurements on human subjects using commercially available hardware with accurate noise modelling.

We present a new approach to Diffuse Correlation Spectroscopy which overcomes the limited light throughput of single mode photon counting techniques, and operates with continuous wave illumination without disturbance from ambient light. Real-time heterodyne holographic detection allows parallel measurement of the power spectrum of a fluctuating electric field across thousands of modes, from which we directly compute flow parameters using a novel Fourier domain model. Our detection and modelling strategy are rigorously validated by modulating the Brownian and flow components of an optical tissue phantom, demonstrating absolute measurements of the Brownian diffusion coefficient in excellent agreement with conventional methods.

Desmoplastic stiffening of breast carcinoma is the bulk scale manifestation of the extra-cellular matrix (ECM) micromechanical remodeling during neoplastic transformation. We have developed a novel optical imaging technology, termed laser speckle micro-rheology (LSM) for evaluating the micro-mechanical properties of tissue and investigating the implications of the mechano-pathological phenomena to the disease progression. Here, we present a new enhancement to the LSM processing scheme to extract the optical properties from speckle patterns and correct for residual speckle modulations to quantify the shear viscoelastic modulus of breast tissues. By accounting for optical variations, we observed an increased significance in the shear moduli differences between benign lesions and tumors and also between tumors of different histological diagnosis.

This study used fNIRS probe to monitor in-vitro blood samples mixture with yeasts during multiple oxygen additions. Results showed that the oxygenation and deoxidation capacity declined along with the number of trials for all the subjects. We also established a method to evaluate the oxygen carrying capacity and verified the method in the experiments. This work has great potential in the clinical diagnosis of hemodynamic diseases related to the oxygen carrying capacity such as anemis.

We report holistic quantification of cutaneous microcirculation with spatial frequency domain imaging (SFDI) and coherent hemodynamics spectroscopy (CHS) based on a dynamic microcirculation PIPE model. A simple device was developed to induce periodic variations in cutaneous blood volume and flow velocity. Both baseline and dynamic features of cutaneous microcirculation for healthy subjects were completely quantified. The CHS findings were further related to SSMD-SFDI imaging of the same healthy subjects under reactive hyperemia protocol. The results demonstrate spatial frequency domain imaging and coherent hemodynamics spectroscopy based on the dynamic microcirculation PIPE model provides a valuable tool for functional studies with hemodynamic-based techniques.

Here we present an imaging strategy for multicolor TPEF microscopy. Firstly, continuum pulses with 700-900 nm spectrum has been generated by pumping pulses from the 100-fs Ti: Sapphire oscillator through the highly nonlinear photonic crystal fibers (HNPCF), which covers the two-photon excitation spectra of common fluorophores. Phase shaping method is used to compensate the dispersion and achieve rapid selective excitation of specific fluorophores at a time. We implement non-negative matrix factorization(NMF) algorithm to achieve unmixing, it can distinguish fluorophores without their spectral information. Combining with selective excitation, three-channel detection and linear unmixing method, Images of 7-color HeLa cells and 4-color mice tumor under the mouse skin fold window chamber were acquired.

We applied magnetic resonance imaging (MRI) pulse sequences for monitoring local changes of proton relaxation times after the local application of skin optical clearing (OC) compositions in tumor-bearing animals.We measured changes in fluorescence intensity and lifetime (FL) of the tumor foci after OC application onto the skin. We observed median FL increase by 53 ps and photon number increase by 30-40% after OC application. We tracked MR signal changes in the regions of interest (ROI) within the cutaneous/subcutaneous space before, during and after OC. The analysis of 1T MR T2-weighted (T2w) fast spin-echo images showed significant quantitative differences between Gaussian noise-normalized MRI signal intensities (Mann-Whitney test, p<0.05).The results suggest that T2w 1T MRI was acceptable for monitoring minute longitudinal changes of the MR signal in the subcutaneous space during and after OC enabling registration of of optical and MR signal fluctuations in the same tissue voxels.

Dynamic FFOCT allows us to see the sub-cellular motion of biological samples. We are able to follow the evolution in the same plane of biological samples for hours thanks to an autofocus procedure. RPE cells are involved in the integrity of retina and vision. We performed a linear scratch assay in RPE cell culture with a surgical scalpel blade, inducing border cell migration at 20.8 µm/h to close the scratch. We also recorded motility of microvilli, thanks to rapid GPU computing. Quantitative live imaging of RPE cell culture with DFFOCT is useful in development of disease models of retinal degeneration.

Decoupled fluorescence Monte Carlo (dfMC) model as the forward model of fluorescence molecular tomography (FMT) is directly derived from the radiance transfer equations. In order to accelerate image reconstruction, we presented a method to reduce the amount of data required for storage in the hard disk. Experiments show that our method not only greatly reduces the amount of data required for storage in the hard disk and accelerates image reconstruction but also maintains the quantitative and positioning accuracy of the conventional method.

We used laser Doppler holography, a full-field imaging technique, to measure blood flow in the retina and choroid with an unmatched temporal resolution. We here report on the measurement of the flow waveforms in retinal arteries and veins after spatio-temporal filtering of the power Doppler. We demonstrate a full field mapping of the local resistivity index, and the possibility to perform unambiguous identification of retinal arteries and veins on the basis of their systolodiastolic variations. This work demonstrates the potential held by laser Doppler holography to study ocular hemodynamics in healthy and diseased eyes.

One aim of optical imaging techniques is to record the time evolution of physiological signatures at high spatial resolutions by detecting changes in optical signals. The ability to detect optical changes associated with physiological events or dynamics is very closely tied to the spatiotemporal resolution and field of view of the system. In this work, we will present a coherent optics-based imaging system that achieves high spatiotemporal resolution (<100µm and >100Hz) in-vivo recordings of physiological signatures (heart rate, breathing) over large 20mm2 areas.

How to write a biophotonics app that reaches more than 500 million people 1. Focus on what you know. In our case that was tissue optics and microcirculation imaging. 2. Watch out for new and especially consumer technologies which could be harnessed in your field. By 2010 smartphones had a good light source, a good camera and sufficient processing power to be a useful biophotonics instrument. 3. Think of a bio problem which concerns many more than 500 million people and which could be solved using this new technology. The WHO had just declared that resting heart rate was a leading indicator of cardiovascular health. 4. Train someone in the necessary skill(s). In our case that was Java which would allow us to program an Android based smartphone. We already knew a lot about tissue optics and blood flow. 5. Give it away for free. We decided to publish the idea and have provided well documented simple versions of the code on GitHub, along with an educational version on Google Play.

Optical coherence tomography (OCT) is a promising research tool for non-invasive imaging of biological tissues. OCT can be used to capture images of the beating Drosophila heart in vivo with micrometer resolution and video-rate imaging speed. Due to its non-invasiveness nature, OCT enables longitudinal imaging of developing flies through the entire life cycle of the insect. Combined with non-invasive optogenetic pacing, this forms a powerful research platform to study developmental biology.

We recently established a set of unique in vivo methods for investigation of early embryonic development and reproduction in mice. Without the use of any contrast agents, these methods allow for live dynamic volumetric imaging of mouse reproductive tract with micro-scale spatial resolution using optical coherence tomography (OCT), in vivo depth-resolved mapping of the cilia location and cilia beat frequency (CBF) in the Fallopian tube (oviduct), and tracking individual sperm and their motility in vivo in the oviduct. Our observations revealed intriguing findings, which question current views on role of cilia in gamete and embryo transfer during preimplantation pregnancy.

Biomechanical signaling is required during cardiac development. Perturbation of heart biomechanics results in a malformed heart, the primary phenotype found in congenital heart disease. Cardiac progenitor cells are responsible for acquiring all cardiac cell fates, expanding, and organizing into a functional heart. How biomechanical signals govern cardiac progenitor cell behavior to achieve cardiac morphogenesis is unknown. In this work, we will implement optogenetic cardiac pacing as a means to control cardiac biomechanics and determine how altered mechanics affects cardiac progenitor cells.

The aim of this study is to investigate delivery pathways and impact of multicomponent chemical agents on skin and subcutaneous tissues both ex vivo and in vivo. Namely, to achieve effective skin OC up to subcutaneous fat layer by combining effective OCA with physical and chemical enhancers. To provide these studies, non-invasive advanced optical techniques, such as MPT combined with FLIM technique and confocal Raman microscopy will be used to quantify impact of OCA on the skin ex vivo and in vivo. For CRM water can be tracked depending on the bounding states or influence on lipids can be determined.

Various tissue optical clearing methods have emerged as important tools for three-dimensional imaging of large-scale tissues or whole-organs. The solvent-based clearing protocols, such as the DISCO-series methods, have certain limitations, such as fast fluorescence quenching, or low clearing performance for heme-rich tissues. To address these issues, we modified and developed advanced optical clearing methods for better fluorescence preservation and application in heme-rich tissues. This work is expected to provide efficient alternatives for clearing and three-dimensional imaging of whole organs and broaden the applications of tissue optical clearing methods.

Congenital coronary anomalies can result in severe consequences such as arrhythmias, sudden death and congenital heart defects (CHDs), however the role of the coronary microvasculature in the formation of CHDs is poorly understood. We combine our custom optical clearing method (LIMPID), fluorescent staining and 3D confocal microscopy to visualize the coronary microvasculature at two developmental stages (day 9, 13) in quail embryos. We discovered a highly organized coronary vessel network that progressively changes in orientation with depth and increases in density with time. In the future, we plan to assess how coronary and cell patterning affect cardiac contraction and conduction.

Early ethanol-exposure has been demonstrated to induce abnormal cardiac function and smaller cardiac cushions compared to controls. Since endocardial cushion formation at the atrioventricular junction (AVJ) is necessary to produce the AVJ conduction delay, we hypothesized that ethanol exposed embryos that develop smaller AVJ cushions would exhibit abnormally fast AVJ conduction. Conduction maps of ethanol exposed quail embryos and controls were imaged using an optical mapping microscope. Cardiac morphology was captured by optical coherence tomography. Our preliminary results show that ethanol exposed embryos that have smaller cushions and develop abnormally fast conduction at the AVJ compared with controls.

It is essentially important to detect cancer in early stage to treat it successfully. Existing optical coherence tomography (OCT) can detect structure with length scale limited by axial resolution. Here, we proposed a new nano-sensitive OCT (nsOCT) in combination with multifractal analysis approach which promises detection of multifractality in nano sensitive sub-micron structure below the axial resolution. The proposed nsOCT based multifractal analysis approach is initially validated in a tissue phantom via simulation. Finally, the proposed method is applied on fresh tissue sample to measure nano-sensitive sub-micron structural multifractality and its alteration from healthy to tumor transition.