Precise and differential profiling of the dynamic correlations and pathophysiological implications of multiplex biological mediators with deep penetration and highly programmed precision remain ...critical challenges in clinics. Here we present an innovative strategy by tailoring a powerful multispectral optoacoustic tomography (MSOT) technique with a photon-upconverting nanoprobe (UCN) for simultaneous visualization of diversely endogenous redox biomarkers with excellent spatiotemporal resolution in living conditions. Upon incorporating two specific radicals-sensitive NIR cyanine fluorophores onto UCNs surface, such nanoprobes can orthogonally respond to disparate oxidative and nitrosative stimulation, and generate spectrally opposite optoacoustic signal variations, which thus achieves compelling superiorities for reversed ratiometric tracking of multiple radicals under dual independent wavelength channels, and significantly, for precise validating of their complex dynamics and correlations with redox-mediated pathophysiological procession in vivo.
Abstract Despite the deeper tissue penetration of photoacoustic (PA) imaging, its sensitivity is generally lower than optical imaging. This fact partially restricts the applications of PA imaging and ...greatly stimulates the development of sensitive PA imaging agents. We herein report that the surface coating of semiconducting polymer nanoparticles (SPNs) with the silica layer can simultaneously amplify fluorescence and PA brightness while maintaining their photothermal conversion efficiency nearly unchanged. As compared with the bare SPNs, the silica-coated SPNs (SPNs-SiO2 ) have higher photothermal heating rate in the initial stage of laser irradiation due to the higher interfacial thermal conductance between the silica layer and water relative to that between the SP and water. Such an interfacial effect consequently results in sharp temperature increase and in turn amplified PA brightness for SPNs-SiO2 . By conjugating poly(ethylene glycol) (PEG) and cyclic-RGD onto SPNs-SiO2 , targeted PA imaging of tumor in living mice is demonstrated after systemic administration, showing a high signal to background ratio. Our study provides a surface engineering approach to amplify the PA signals of organic nanoparticles for molecular imaging.
A dual‐phase all‐inorganic composite CsPbBr3‐CsPb2Br5 is developed and applied as the emitting layer in LEDs, which exhibited a maximum luminance of 3853 cd m–2, with current density (CE) of ≈8.98 cd ...A–1 and external quantum efficiency (EQE) of ≈2.21%, respectively. The parasite of secondary phase CsPb2Br5 nanoparticles on the cubic CsPbBr3 nanocrystals could enhance the current efficiency by reducing diffusion length of excitons on one side, and decrease the trap density in the band gap on the other side. In addition, the introduction of CsPb2Br5 nanoparticles could increase the ionic conductivity by reducing the barrier against the electronic and ionic transport, and improve emission lifetime by decreasing nonradiative energy transfer to the trap states via controlling the trap density. The dual‐phase all‐inorganic CsPbBr3‐CsPb2Br5 composite nanocrystals present a new route of perovskite material for advanced light emission applications.
Dual‐phase CsPbBr3‐CsPb2Br5 composites for all‐inorganic perovskite light emitting diodes (LEDs) are fabricated, which exhibit significantly improved performance, representing a great increase in the CE and EQE, about 21‐ and 18‐fold improvement than that of the best reported CsPbBr3 LEDs. The dual‐phase all‐inorganic CsPbBr3‐CsPb2Br5 composite nanocrystals present a new route of perovskite material for advanced light emission applications.
A bionic artificial device commonly integrates various distributed functional units to mimic the functions of biological sensory neural system, bringing intricate interconnections, complicated ...structure, and interference in signal transmission. Here we show an all-in-one bionic artificial nerve based on a separate electrical double-layers structure that integrates the functions of perception, recognition, and transmission. The bionic artificial nerve features flexibility, rapid response (<21 ms), high robustness, excellent durability (>10,000 tests), personalized cutability, and no energy consumption when no mechanical stimulation is being applied. The response signals are highly regionally differentiated for the mechanical stimulations, which enables the bionic artificial nerve to mimic the spatiotemporally dynamic logic of a biological neural network. Multifunctional touch interactions demonstrate the enormous potential of the bionic artificial nerve for human-machine hybrid perceptual enhancement. By incorporating the spatiotemporal resolution function and algorithmic analysis, we hope that bionic artificial nerves will promote further development of sophisticated neuroprosthetics and intelligent robotics.
A new type of silicon-based Mach-Zehnder interference (MZI) temperature sensor chip with "mosquito coil" structure was designed. The sensor chip used a new MZI interference structure. After the light ...entered the chip, it split and interfered in the combiner of the chip. The change in the surrounding temperature will cause the refractive index of the waveguide to change, which will cause the output light intensity to change. The sensor used a frequency stabilized laser that was based on a Bragg grating fiber. The experimental results showed that this structure could achieve a resolution of 0.002 °C and measuring range of 30 °C.
The analysis of infrared spectroscopy of substances is a non-invasive measurement technique that can be used in analytics. Although the main objective of this study is to provide a review of machine ...learning (ML) algorithms that have been reported for analyzing near-infrared (NIR) spectroscopy from traditional machine learning methods to deep network architectures, we also provide different NIR measurement modes, instruments, signal preprocessing methods, etc. Firstly, four different measurement modes available in NIR are reviewed, different types of NIR instruments are compared, and a summary of NIR data analysis methods is provided. Secondly, the public NIR spectroscopy datasets are briefly discussed, with links provided. Thirdly, the widely used data preprocessing and feature selection algorithms that have been reported for NIR spectroscopy are presented. Then, the majority of the traditional machine learning methods and deep network architectures that are commonly employed are covered. Finally, we conclude that developing the integration of a variety of machine learning algorithms in an efficient and lightweight manner is a significant future research direction.
Diabetic patients need long-term and frequent glucose monitoring to assist in insulin intake. The current finger-prick devices are painful and costly, which places noninvasive glucose sensors in high ...demand. In this review paper, we list several advanced electromagnetic (EM)-wave-based technologies for noninvasive glucose measurement, including infrared (IR) spectroscopy, photoacoustic (PA) spectroscopy, Raman spectroscopy, fluorescence, optical coherence tomography (OCT), Terahertz (THz) spectroscopy, and microwave sensing. The development of each method is discussed regarding the fundamental principle, system setup, and experimental results. Despite the promising achievements that have been previously reported, no established product has obtained FDA approval or survived a marketing test. The limitations of, and prospects for, these techniques are presented at the end of this review.
Photoacoustic sensing and imaging techniques have been studied widely to explore optical absorption contrast based on nanosecond laser illumination. In this paper, we report a long laser pulse ...induced dual photoacoustic (LDPA) nonlinear effect, which originates from unsatisfied stress and thermal confinements. Being different from conventional short laser pulse illumination, the proposed method utilizes a long square-profile laser pulse to induce dual photoacoustic signals. Without satisfying the stress confinement, the dual photoacoustic signals are generated following the positive and negative edges of the long laser pulse. More interestingly, the first expansion-induced photoacoustic signal exhibits positive waveform due to the initial sharp rising of temperature. On the contrary, the second contraction-induced photoacoustic signal exhibits exactly negative waveform due to the falling of temperature, as well as pulse-width-dependent signal amplitude. An analytical model is derived to describe the generation of the dual photoacoustic pulses, incorporating Gruneisen saturation and thermal diffusion effect, which is experimentally proved. Lastly, an alternate of LDPA technique using quasi-CW laser excitation is also introduced and demonstrated for both super-contrast in vitro and in vivo imaging. Compared with existing nonlinear PA techniques, the proposed LDPA nonlinear effect could enable a much broader range of potential applications.
Photoacoustic imaging and sensing have been studied extensively to probe the optical absorption of biological tissue in multiple scales ranging from large organs to small molecules. However, its ...elastic oscillation characterization is rarely studied and has been an untapped area to be explored. In literature, photoacoustic signal induced by pulsed laser is commonly modelled as a bipolar "N-shape" pulse from an optical absorber. In this paper, the photoacoustic damped oscillation is predicted and modelled by an equivalent mass-spring system by treating the optical absorber as an elastic oscillator. The photoacoustic simulation incorporating the proposed oscillation model shows better agreement with the measured signal from an elastic phantom, than conventional photoacoustic simulation model. More interestingly, the photoacoustic damping oscillation effect could potentially be a useful characterization approach to evaluate biological tissue's mechanical properties in terms of relaxation time, peak number and ratio beyond optical absorption only, which is experimentally demonstrated in this paper.
PDF
