Self-confocal NIR-II fluorescence microscopy for multifunctional in vivo imaging

Fluorescence imaging in the second near-infrared window(NIR-II,900–1880 nm)with less scattering background in biological tissues has been combined with the confocal microscopic system for achieving deep in vivo imaging with high spatial resolution.However,the traditional NIR-IIfluorescence confocal microscope with separate excitation focus and detection pinhole makes it possess low confocal e±ciency,as well as di±cultly to adjust.Two types of upgraded NIR-IIfluorescence confocal microscopes,sharing the same pinhole by excitation and emission focus,leading to higher confocal e±ciency,are built in this work.One type is-ber-pinhole-based confocal microscope applicable to CW laser excitation.It is constructed forfluorescence intensity imaging with large depth,high stabilization and low cost,which could replace multiphotonfluorescence microscopy in some applications(e.g.,cerebrovascular and hepatocellular imaging).The other type is air-pinhole-based confocal microscope applicable to femtosecond(fs)laser excitation.It can be employed not only for NIR-IIfluorescence intensity imaging,but also for multi-channelfluorescence lifetime imaging to recognize different structures with similarfluorescence spectrum.Moreover,it can be facilely combined with multiphotonfluorescence microscopy.A single fs pulsed laser is utilized to achieve up-conversion(visible multiphotonfluorescence)and down-conversion(NIR-II one-photonfluorescence)excitation simultaneously,extending imaging spectral channels,and thus facilitates multi-structure and multi-functional observation.

Lipid droplets imaging with three-photon microscopy

Lipid droplets(LDs)participate in many physiological processes,the abnormality of which will cause chronic diseases and pathologies such as diabetes and obesity.It is crucial to monitor the distribution of LDs at high spatial resolution and large depth.Herein,we carried three-photon imaging of LDs in fat liver.Owing to the large three-photon absorption cross-section of the luminogen named NAP-CF_(3)(1:67×10^(-79) cm^(6) s^(2)),three-photon fluorescence fat liver imaging reached the largest depth of 80μm.Fat liver diagnosis was successfully carried out with excellent performance,providing great potential for LDs-associated pathologies research.

A ggregation-induced emission nanoparticles for in vivo three-photon fuorescence microscopic rat brain angiography

Rodents are popular biological models for physiological and behavioral research in neuroscience and rats are better models than mice due to their higher genome similarity to human and more accessible surgical procedures.However,rat brain is larger than mice brain and it needs powerful imaging tools to implement better penetration against the scattering of the thicker brain tissue.Three-photon fluorescence microscopy(3PFM)combined with near-infrared(NIR)excitation has great potentials for brain circuits imaging beause of its abilities of anti scattering,deep-tissue imaging,and high signal-to-noise ratio(SNR).In this work,a type of AIE lumninogen with red fuorescence was synthesized and encapsulated with Pluronic F-127 to make up form nano-particles(NPs).Bright DCDPP-2TPA NPs were employed for in trino three-photon fuorescent laser scanning microscopy of blood vessels in rats brain under 1550 nm femtosecond laser exci-tation.A fine three-dimensional(3D)reconstruction up to the deepness of 600 pm was achieved and the blood flow velocity of a selected vessel was measured in vrito as well.Our 3PFM deep brain imaging method simultaneously recorded the morphology and function of the brain blood vessels in vivo in the rat model.Using this angiography combined with the arsenal of rodent's brain disease,models can accelerate the neuroscience research and clinical diagnosis of brain disease in the future.

NIR-II ?uorescence in vivo confocal microscopy with aggregation-induced emission dots

Significantly reduced tissue scattering of fluorescence signals in the second near-infrared(NIR-Ⅱ,1,000–1,700 nm)spectral region offers opportunities for large-depth in vivo bioimaging.Nowadays,most reported works concerning NIR-II fluorescence in vivo bioimaging are realized by wide-field illumination and 2D-arrayed detection(e.g.,via InGaAs camera),which has high temporal resolution but limited spatial resolution due to out-of-focus signals.Combining NIR-II fluorescence imaging with confocal microscopy is a good approach to achieve high-spatial resolution visualization of biosamples even at deep tissues.In this presented work,a NIR-II fluorescence confocal microscopic system was setup.By using a kind of aggregation-induced emission(AIE)dots as NIR-II fluorescent probes,800 lm-deep 3D in vivo cerebrovascular imaging of a mouse was obtained,and the spatial resolution at 700 lm depth could reach 8.78 lm.Moreover,the time-correlated single photon counting(TCSPC)technique and femtosecond laser excitation were introduced into NIR-II fluorescence confocal microscopy,and in vivo confocal NIR-II fluorescence lifetime microscopic imaging(FLIM)of mouse cerebral vasculature was successfully realized.

NIR-IIb excitable bright polymer dots with deep-red emission for in vivo through-skull three-photon fluorescence bioimaging

It is of great significance to study the brain structure and function in deep-tissue for neuroscience research and bio-medical applications because of the urgent demand for precise theranostics.Three-photon fluorescence microscopic(3PFM)bioimaging excited by the light in near-infrared IIb(NIR-IIb,1,500–1,700 nm)spectral region is one of the most promising imaging techniques with the advantages of high spatial resolution,large imaging depth,and reduced scattering.Herein,a type of NIR-IIb light excitable deep-red emissive semiconducting polymer dots(P-dots)with bright 3PF and large three-photon absorption cross-section(σ3)at 1,550 nm was prepared.Then the P-dots were functionalized with polystyrene polymer polystyrene graft ethylene oxide functionalized with carboxyl groups(PS-PEG-COOH)and modified with NH2-poly(ethylene glycol)(PEG)to synthesis photochemically stable and biocompatible P-dots nanoparticles(NPs).Further the P-dots NPs were utilized for in vivo 3PFM bioimaging of cerebral vasculature with and without the brain skull under 1,550 nm femtosecond(fs)laser excitation.In vivo 3PFM bioimaging of the mice cerebral vasculature at various vertical depths was obtained.Moreover,a vivid three-dimensional structure of the mice vascular architecture beneath the skull was reconstructed.At the depth of 350μm beneath the brain skull,3.8μm blood vessels could still be clearly recognized.NIR-IIb excitable P-dots assisted 3PFM bioimaging has great potential in accurate deep tissue bioimaging.

Toxicity assessment and long-term three-photon fluorescence imaging of bright aggregation-induced emission nanodots in zebrafish

Aggregation-induced emission （AIE） luminogen displays bright fluorescence and has photobleaching resistance in its aggregation state. It is an ideal fluorescent contrast agent for bioimaging. Multiphoton microscopy is an important tool for bioimaging since it possesses the ability to penetrate deep into biological tissues. Herein, we used AIE luminogen together with multiphoton microscopy for long-term imaging of zebrafish. A typical AIE luminogen, 2,3-bis（4-（phenyl（4- （1,Z2-triphenylvinyl） phenyl）amino）phenyl） fumaronitrile （TPE-TPA-FN or TTF）, was encapsulated with 1,2-distearoyl-sn-glycero-3-phosphoethanola-mine-N- [methoxy（polyethylene glycol）-2000] （DSPE-mPEG2000） to form nanodots that exhibited bright three-photon fluorescence under 1,560 nm-femtosecond （fs） laser excitation. The TTF-nanodots were chemically stable in a wide range of pH values and showed no in vivo toxicity in zebrafish according to a series of biological tests. The TTF-nanodots were microinjected into zebrafish embryos, and the different growth stages of the labeled embryos were monitored with a three-photon fluorescence microscope. TTF-nanodots could be traced inside the zebrafish body for as long as 120 hours. In addition, the TTF-nanodots were utilized to target the blood vessel of zebrafish, and three-photon fluorescence angiogram was performed. More importantly, these nanodots were highly resistant to photobleaching under 1,560 nm-fs excitation, allowing long-term imaging of zebrafish.

A Through-Intact-Skull(TIS)chronic window technique for cortical structure and function observation in mice

Modern optical imaging techniques provide powerful tools for observing cortical structure and functions at high resolutions.Various skull windows have been established for different applications of cortical imaging,and each has its advantages and limitations.Most critical of the limitations,none of the current skull windows is suitable for observing the responses to some acute craniocerebral injuries on a large scale and at high resolution.Here,we developed a“Through-Intact-Skull(TIS)window”that enables the observation of an immune response on a bilateral cortical scale and at single-cell resolution after traumatic brain injury without affecting the pathological environment of the brain.The TIS window also has the advantages of craniotomy-freeness,centimeter-field of view,synaptic resolution,large imaging depth,long-term observation capability,and suitability for awake mice.Therefore,the TIS window is a promising new approach for intravital cortical microscopy in basic research in neuroscience.

Internet of radio and light:5G building network radio and edge architecture

The Internet of Radio-Light(IoRL)is a cutting-edge system paradigm to enable seamless 5G service provision in indoor environments,such as homes,hospitals,and museums.The system draws on innovative architectural structure that sits on the synergy between the Radio Access Network(RAN)technologies of millimeter Wave communications(mmWave)and Visible Light Communications(VLC)for improving network throughput,latency,and coverage compared to existing efforts.The aim of this paper is to introduce the IoRL system architecture and present the key technologies and techniques utilised at each layer of the system.Special emphasis is given in detailing the IoRL physical layer(Layer 1)and Medium Access Control layer(MAC,Layer 2)by means of describing their unique design characteristics and interfaces as well as the robust IoRL methods of improving the estimation accuracy of user positioning relying on uplink mmWave and downlink VLC measurements.

Erratum to:NIR-IIb excitable bright polymer dots with deep-red emission for in vivo through-skull three-photon fluorescence bioimaging

Erratum to Nano Research 2020,13(10):2632–2640 https://doi.org/10.1007/s12274-020-2902-x Figures S5 and S6 in the Electronic Supplementary material(ESM)were unfortunately mistakenly used.This error did not affect any of the conclusions from the published paper.Instead of Figure S5 Microscopic images of tissue sections from mice. All tissues of (a)heart, (b) lung, (c) liver, (d) spleen, (e) kidney and (f) brain were excised fromthe experimental mice 24 hours after the administration of P-dots (200 μL,0.125 mg·mL^(-1) in 1 × PBS, right) and the control mice (left) treated with 1 × PBS(200 μL). Scale bar: 50 μm.