Fluorescence imaging has become a fundamental tool for biomedical applications; nevertheless, its intravital imaging capacity in the conventional wavelength range (400–950 nm) has been restricted by ...its extremely limited tissue penetration. To tackle this challenge, a novel imaging approach using the fluorescence in the second near-infrared window (NIR-II, 1000–1700 nm) has been developed in the past decade to achieve deep penetration and high-fidelity imaging, and thus significant biomedical applications have begun to emerge. In this Perspective, we first examine recent discoveries and challenges in the development of novel NIR-II fluorophores and compatible imaging apparatuses. Subsequently, the recent advances in bioimaging, biosensing, and therapy using such a cutting-edge imaging technique are highlighted. Finally, based on the achievement in the representative studies, we elucidate the main concerns regarding this imaging technique and give some advice and prospects for the development of NIR-II imaging for future biomedical applications.
Wheat (Triticum aestivum L.) is a major food crop worldwide. Low soil phosphorus content and drought are the main constraints on wheat production in Xinjiang, China. In this study, the ionic and ...metabolic responses of one wheat variety ("Xindong20") to drought stress simulated by using polyethylene glycol 6000 (PEG-6000) were investigated under low phosphorus (LP) and conventional phosphorus (CP) conditions by analysing wheat mineral elements and metabolites. Besides, due to xanthohumol was the metabolite with the most significant difference in expression detected in "Xindong 20", two wheat variety "Xindong20 and Xindong 23" were selected to conduct the germination test simultaneously, to further verify the function of xanthohumol in wheat growth. Xanthohumol was mixed with PEG solution (20%) to prepare PEG solutions with different concentrations (0%, 0.1%, 0.5%, and 1%) of xanthohumol. Then wheat grains were soaked in the solutions for 20 hours, followed by a germination test. After 7 days, the indicators including shoot length, max root length, and root number were determined to identify whether the metabolite was beneficial to improve the drought tolerance of wheat. The results showed that the root density and volume of wheat in LP treatment were higher than those in CP treatment. The roots underwent programmed cell death both in LP and CP treatments under PEG-6000-simulated drought stress, however, the DNA degradation in root cells in LP treatment was lower than that in CP treatment after rehydration for 3 d. Before drought stress, the malondialdehyde (MDA) content in shoot and the peroxidase (POD) activity in root in LP treatment were significantly higher than those in CP treatment, while the soluble sugar content and chlorophyll content in LP treatment were significantly lower than those in CP treatment. During drought stress, the POD activity maintained at a high level and the soluble sugar content gradually increased in LP treatment. After rehydration, the MDA content still maintained at a high level in LP treatment, the superoxide dismutase (SOD) activity increased, and the contents of soluble sugar and chlorophyll were significantly higher than those in CP treatment. The analysis of mineral elements and metabolites showed that the wheat in CP treatment was more sensitive to drought stress than that in LP treatment. Besides, the effect of drought stress was greater on shoot than on root in CP treatment, while it was opposite in LP treatment. The effect of drought stress on sugar metabolism gradually increased. Germination assays showed that 0.1% exogenous xanthohumol addition could significantly increase the shoot length of the two wheat varieties under drought stress. Appropriate low phosphorus supply could increase antioxidant enzyme activity in wheat, and enhance sugar metabolism to regulate osmotic balance, as well as the accumulation of various organic acids to maintain the intracellular ion homeostasis. Therefore, compared to the conventional phosphorus supply level, appropriate low phosphorus supply can significantly improve the drought tolerance of wheat. Additionally, addition of 0.1% exogenous xanthohumol, an important differential expressed metabolite in drought-stressed wheat, could effectively promote wheat shoot growth under drought stress.
Here, we present a protocol for the analysis of barometric pressure data from multiple stations for the globally propagating spherical shockwaves generated by catastrophic explosions. We demonstrate ...the analytical procedure using the Tonga underwater volcano eruption of January 2022. We also present a protocol to make a data recorder using off-the-shelf electronic components for barometric pressure measurements at ∼1 Hz. The data recorder and the analysis protocol can be used to study similar future catastrophic events.
For complete details on the use and execution of this protocol, please refer to Li (2022).1
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•Make a solar-powered data recorder that integrates air pressure, GPS, and SD card•Identifying shockwave signals and their arrival times from air pressure data•Computation of spherical shockwave propagation speed•Application of low-pass, high-pass, and band-pass Fourier filters to analyze ringing
Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.
Here, we present a protocol for the analysis of barometric pressure data from multiple stations for the globally propagating spherical shockwaves generated by catastrophic explosions. We demonstrate the analytical procedure using the Tonga underwater volcano eruption of January 2022. We also present a protocol to make a data recorder using off-the-shelf electronic components for barometric pressure measurements at ∼1 Hz. The data recorder and the analysis protocol can be used to study similar future catastrophic events.
The eruption of the Tonga volcano created globally propagating spherical shockwaves in the atmosphere. Analyses are done to data from two southern U.S. stations of the author sampling at 3–21 s ...intervals and 189 weather stations at 1–5 min intervals. The shockwaves arrived from two routes in the atmosphere: the shortest spherical arc and the longer spherical arc through the antipole. In most stations, signals up to the 6th path of shockwaves were recorded as the waves traveled around the globe multiple times. The speed of shockwaves is estimated to be 309.5 ± 2.9 m/s, consistent with the speed of sound at the top of the troposphere where a waveguide exists. Discussion is made on the post-shockwave ringing of 4–8 min as higher amplitude oscillations above the level of pre-shockwaves background noise. A theoretical wave dispersion is derived which verifies that the spherical shockwave’s phase speed is the same as the speed of sound.
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•Dispersion equation of global spherical shockwaves from a point source derived•Air pressure of 3–21 s recorded the shockwaves from the Tonga volcano eruption•Shockwaves and ringing with higher energy analyzed using data from 191 stations•Shockwaves up to 6th pass from 191 stations consistent with global spherical waves
Earth sciences; Geology; Volcano; Atmospheric observation.
This paper discusses the direct fabrication of ultrathin Ni(OH)2 nanosheets on substrates via a facile solvothermal process, which is free from the use of additional surfactants. The precursor is ...converted into porous NiO nanosheets via heat treatment. The thickness and morphology of the nanosheets is controlled by manipulating the ethanol content in the solvent. The acetone sensing performance of all samples has been evaluated, as observed, the 75% ethanol-based NiO gas sensor (NiO-75), demonstrates ultrahigh acetone sensitivity, the response value can reach 60%, when the NiO nanosheet sensor detects 100 ppb acetone gas, ultralow detection limit (0.8 ppb acetone), and good stability. The excellent sensing performance of the NiO nanosheets can be attributed to their porous structure, which provides a large surface area and crystal facet with affinity to acetone gas. Moreover, the porous structure facilitates the diffusion of gas samples and products to improve the acetone detection sensitivity. Furthermore, the NiO-75 sensor demonstrates superior acetone selectivity, against other interfering gases. The findings of this study indicate that low cost NiO nanosheets fabricated via a simple process could be considered as potential, candidates for use in commercial acetone sensing applications.,
•Ultrathin and Porous NiO nanosheets are synthesized through a facile one-step solvothermal method on gas sensor substrate.•The 75% ethanol-based gas sensor can detect acetone gas with a concentration as low as 10 ppb at optimum temperature.•The high acetone sensing performance of NiO nanosheets is owing to the large surface area induced by the porous structure.
Image-guided photothermal therapy (PTT) is an attractive strategy to improve the diagnosis accuracy and treatment outcomes by monitoring the accumulation of photothermal agents in tumors in real-time ...and determining the best treatment window. Taking advantage of the superior imaging quality of NIR-II fluorescence imaging and remote-controllable phototherapy modality of PTT, we developed a facile macromolecular fluorophore (PF) by conjugating a small-molecule NIR-II fluorophore (Flav7) with an amphiphilic polypeptide. The PF can form uniform micelles in aqueous solution, which exhibit a slight negative charge. In vitro experimental results showed that the PF nanoparticles showed satisfactory photophysical properties, prominent photothermal conversion efficiency (42.3%), excellent photothermal stability, negligible cytotoxicity, and photothermal toxicity. Meanwhile, the PF can visualize and feature the tumors by NIR-II fluorescence imaging owing to prolonged blood circulation time and enhanced accumulation in tumors. Moreover, in vivo studies revealed that the PF nanoparticles achieved an excellent photothermal ablation effect on tumors with a low dose of NIR-II dye and light irradiation, and the process can be traced by NIR fluorescence imaging.
An excellent mesoporous silica nanoparticle (MSN) based drug deliver system (DDS) was reported for regulated anticancer drug release upon the irradiation of either one- or two-photon excitation. In ...this system, the coumarin grafted on MSN acted as both the “phototrigger” for the drug release and fluorescence group for cell luminescence imaging. External light manipulations such as changing irradiation wavelength, intensity, and time can regulate the release of the anticancer drug precisely. Biological studies in vitro suggest that the drug carrier can effectively deliver the anticancer drug into intracellular environs and, hence, promote the drug action to kill the cancer cells upon irradiation. We envision that the good biocompatibility, cellar uptake property, and efficient photoregulated drug release will be of great benefit to future controlled release in vivo biomedical applications.
Ag2S quantum dots (QDs) have attracted increasing attention due to their appealing optical properties in the near-infrared regime. However, a full understanding of the quantum confinement effect of ...Ag2S QDs has not been achieved so far. Herein, for the first time, the size-dependent excited state optical properties of Ag2S QDs are systematically investigated by photoluminescence (PL), PL excitation (PLE), and time-resolved PL spectroscopy. Experimentally, we determine the exciton Bohr radius of Ag2S QDs as 2.2 nm, which is highly consistent with theoretical results.
Among the various immunological and non-immunological tumor-promoting activities of myeloid-derived suppressor cells (MDSCs), their immunosuppressive capacity remains a key hallmark. Effort in the ...past decade has provided us with a clearer view of the suppressive nature of MDSCs. More suppressive pathways have been identified, and their recognized targets have been expanded from T cells and natural killer (NK) cells to other immune cells. These novel mechanisms and targets afford MDSCs versatility in suppressing both innate and adaptive immunity. On the other hand, a better understanding of the regulation of their development and function has been unveiled. This intricate regulatory network, consisting of tumor cells, stromal cells, soluble mediators, and hostile physical conditions, reveals bi-directional crosstalk between MDSCs and the tumor microenvironment. In this article, we will review available information on how MDSCs exert their immunosuppressive function and how they are regulated in the tumor milieu. As MDSCs are a well-established obstacle to anti-tumor immunity, new insights in the potential synergistic combination of MDSC-targeted therapy and immunotherapy will be discussed.
Combined chemotherapy and immunotherapy have demonstrated great potential in cancer treatment. However, it is difficult to provide clear information of the pharmacokinetics and pharmacodynamics of ...chemodrugs and transplanted immune cells in vivo by traditional approaches, resulting in inadequate therapy. Here, a multiplexed intravital imaging strategy by using fluorescence in the second near‐infrared window (NIR‐II) is first developed to visualize the two events of chemotherapy and immunotherapy in vivo, so that a combinational administration is programed to improve the therapeutical effects against a mouse model of human breast cancer. In detail, Ag2Se quantum dots (QDs) (λEm = 1350 nm) loaded with stromal‐cell‐derived factor‐1α (SDF‐1α) and chemodrug doxorubicin (DOX) are first administrated to deliver the SDF‐1α and DOX to the tumor site. After their arrival, monitored by Ag2Se QD fluorescence, natural killer (NK)‐92 cells labeled with Ag2S QDs (λEm = 1050 nm) are intravenously injected so that the cells are recruited to the tumor by the chemotaxis of SDF‐1α, which is visualized by Ag2S QD fluorescence. Such an imaging approach allows simultaneous evaluation of the behaviors of individual injections in vivo, and facilitates optimized administration regimens, resulting in enhanced tumor inhibition.
A multiplexed second‐near‐infrared‐window fluorescence‐imaging strategy is developed to reveal the two events of chemotherapy and immunotherapy in vivo, so that the combinational administration of chemotherapy and immunotherapy is programed to achieve the optimal therapeutical effects.
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