Professional Education


  • Doctor of Philosophy, Chinese Academy Of Sciences (2017)

All Publications


  • Improving photoacoustic-imaging axial positioning accuracy and signal-to-noise ratio using acoustic echo effect SENSORS AND ACTUATORS A-PHYSICAL Zhao, W., Yu, H., Wen, Y., Li, P., Wang, X., Wang, F., Yang, Y., Liu, L., Li, W. 2021; 329
  • In vivo NIR-II structured-illumination light-sheet microscopy. Proceedings of the National Academy of Sciences of the United States of America Wang, F., Ma, Z., Zhong, Y., Salazar, F., Xu, C., Ren, F., Qu, L., Wu, A. M., Dai, H. 2021; 118 (6)

    Abstract

    Noninvasive optical imaging with deep tissue penetration depth and high spatiotemporal resolution is important to longitudinally studying the biology at the single-cell level in live mammals, but has been challenging due to light scattering. Here, we developed near-infrared II (NIR-II) (1,000 to 1,700 nm) structured-illumination light-sheet microscopy (NIR-II SIM) with ultralong excitation and emission wavelengths up to 1,540 and 1,700 nm, respectively, suppressing light scattering to afford large volumetric three-dimensional (3D) imaging of tissues with deep-axial penetration depths. Integrating structured illumination into NIR-II light-sheet microscopy further diminished background and improved spatial resolution by approximately twofold. In vivo oblique NIR-II SIM was performed noninvasively for 3D volumetric multiplexed molecular imaging of the CT26 tumor microenvironment in mice, longitudinally mapping out CD4, CD8, and OX40 at the single-cell level in response to immunotherapy by cytosine-phosphate-guanine (CpG), a Toll-like receptor 9 (TLR-9) agonist combined with OX40 antibody treatment. NIR-II SIM affords an additional tool for noninvasive volumetric molecular imaging of immune cells in live mammals.

    View details for DOI 10.1073/pnas.2023888118

    View details for PubMedID 33526701

  • Advances in Dielectric Microspherical Lens Nanoscopy: Label-Free Superresolution Imaging IEEE NANOTECHNOLOGY MAGAZINE Li, P., Li, G., Yu, H., Wang, F., Liu, L., Jung Li, W. 2021; 15 (1): 38–51
  • Near-Infrared-II Nanoparticles for Cancer Imaging of Immune Checkpoint Programmed Death-Ligand 1 and Photodynamic/Immune Therapy. ACS nano Liu, Q., Tian, J., Tian, Y., Sun, Q., Sun, D., Wang, F., Xu, H., Ying, G., Wang, J., Yetisen, A. K., Jiang, N. 2021

    Abstract

    Development of second near-infrared (NIR-II) nanoparticles (NPs) with high biocompatibility, low toxicity, and high singlet oxygen quantum yield (PhiDelta) to prevent tumor recurrence is highly desirable in molecular imaging and photodynamic/immune combination therapy. Here, theranostic photosensitizer BODIPY (BDP)-I-N-anti-PD-L1 NPs were developed by encapsulating the photosensitizer BDP-I-N with amphipathic poly(styrene-co-chloromethylstyrene)-graft-poly(ethylene glycol) nanocarriers through self-assembly functionalization with programmed cell death-ligand 1 (PD-L1) monoclonal antibody. These NPs exhibit highly intensive luminescence in the NIR-II window (1000-1700 nm) to real-time imaging of immune checkpoint PD-L1, high singlet oxygen quantum yield (PhiDelta = 73%), and an eliminating effect of primary cancers. The NPs also allow for profiling PD-L1 expression as well as accumulating in MC38 tumor and enabling molecular imaging in vivo. Upon an 808 nm laser excitation, the targeted NPs produce an emission wavelength above 1200 nm to image a tumor to a normal tissue signal ratio (T/NT) at an approximate value of 14.1. Moreover, the MC38 tumors in mice are eliminated by combining photodynamic therapy and immunotherapy within 30 days, with no tumor recurrence within a period of 40 days. In addition, the tumors do not grow in the rechallenged mice within 7 days of inoculation. Such a strategy shows a durable immune memory effect against tumor rechallenging without toxic side effects to major organs.

    View details for DOI 10.1021/acsnano.0c05317

    View details for PubMedID 33426893

  • Deep learning for in vivo near-infrared imaging. Proceedings of the National Academy of Sciences of the United States of America Ma, Z., Wang, F., Wang, W., Zhong, Y., Dai, H. 2021; 118 (1)

    Abstract

    Detecting fluorescence in the second near-infrared window (NIR-II) up to 1,700 nm has emerged as a novel in vivo imaging modality with high spatial and temporal resolution through millimeter tissue depths. Imaging in the NIR-IIb window (1,500-1,700 nm) is the most effective one-photon approach to suppressing light scattering and maximizing imaging penetration depth, but relies on nanoparticle probes such as PbS/CdS containing toxic elements. On the other hand, imaging the NIR-I (700-1,000 nm) or NIR-IIa window (1,000-1,300 nm) can be done using biocompatible small-molecule fluorescent probes including US Food and Drug Administration-approved dyes such as indocyanine green (ICG), but has a caveat of suboptimal imaging quality due to light scattering. It is highly desired to achieve the performance of NIR-IIb imaging using molecular probes approved for human use. Here, we trained artificial neural networks to transform a fluorescence image in the shorter-wavelength NIR window of 900-1,300 nm (NIR-I/IIa) to an image resembling an NIR-IIb image. With deep-learning translation, in vivo lymph node imaging with ICG achieved an unprecedented signal-to-background ratio of >100. Using preclinical fluorophores such as IRDye-800, translation of 900-nm NIR molecular imaging of PD-L1 or EGFR greatly enhanced tumor-to-normal tissue ratio up to 20 from 5 and improved tumor margin localization. Further, deep learning greatly improved in vivo noninvasive NIR-II light-sheet microscopy (LSM) in resolution and signal/background. NIR imaging equipped with deep learning could facilitate basic biomedical research and empower clinical diagnostics and imaging-guided surgery in the clinic.

    View details for DOI 10.1073/pnas.2021446118

    View details for PubMedID 33372162

  • Thiophene donor for NIR-II fluorescence imaging-guided photothermal/photodynamic/chemo combination therapy. Acta biomaterialia Liu, Q. n., Tian, J. n., Tian, Y. n., Sun, Q. n., Sun, D. n., Liu, D. n., Wang, F. n., Xu, H. n., Ying, G. n., Wang, J. n., Yetisen, A. K., Jiang, N. n. 2021

    Abstract

    Organic fluorophores/photosensitizers have been widely used in biological imaging and photodynamic and photothermal combination therapy in the first near-infrared (NIR-I) window. However, their applications in the second near-infrared (NIR-II) window are still limited primarily due to low fluorescence quantum yields (QYs). Here, a boron dipyrromethene (BDP) is created as a molecularly engineered thiophene donor unit with high QYs to the redshift. Thiophene insertion initiates substantial redshifts of the absorbance as compared to its counterparts in which iodine is introduced. The fluorescent molecule can be triggered by an NIR laser with a single wavelength, thereby producing emission in the NIR-II windows. Single NIR laser-triggered phototherapeutic nanoparticles (NPs) are developed by encapsulating the BDP and the chemotherapeutic drug docetaxel (DTX) by using a synthetic amphiphilic poly(styrene-co-chloromethyl styrene)-graft-poly(ethylene glycol) functionalized with folic acid (FA). These BDP-T-N-DTX-FA NPs not only show superior solubility and high singlet oxygen QY (ΦΔ=62%) but also demonstrate single NIR laser-triggered multifunctional characteristics. After intravenous administration of the NPs into 4T1 tumor-bearing mice, the accumulation of the NPs in the tumor showed a high signal-to-background ratio (11.8). Furthermore, 4T1 tumors in mice were almost eradicated by DTX released from the BDP-T-N-DTX-FA NPs under single NIR laser excitation and the combination of photodynamic therapy (PDT) and photothermic therapy (PTT). STATEMENT OF SIGNIFICANCE: : The application of organic photosensitizers is still limited primarily due to low fluorescence quantum yields (QYs) in the second near-infrared (NIR-II) window. Here, a boron dipyrromethene (BDP) as a molecularly engineered thiophene donor unit with high QYs to the redshift is created. Phototherapeutic nanoparticles (NPs) are developed by encapsulating the BDP and docetaxel (DTX) using a synthetic amphiphilic poly(styrene-co-chloromethyl styrene)-graft-poly(ethylene glycol) functionalized with folic acid (FA). These BDP-T-N-DTX-FA NPs not only show high singlet oxygen QY (ΦΔ=62%) but also demonstrate single NIR laser-triggered multifunctional characteristics and a high signal-to-background ratio (11.8). Furthermore, 4T1 tumors in mice were almost eradicated by DTX released from the BDP-T-N-DTX-FA NPs under single NIR laser excitation and the PDT/PTT combination therapy.

    View details for DOI 10.1016/j.actbio.2021.03.064

    View details for PubMedID 33831570

  • Scanning Super-resolution Imaging in Enclosed Environment by Laser Tweezer Controlled Superlens. Biophysical journal Wen, Y., Yu, H., Zhao, W., Li, P., Wang, F., Ge, Z., Wang, X., Liu, L., Li, W. J. 2020

    Abstract

    Super-resolution imaging using microspheres has attracted tremendous scientific attention recently because it has managed to overcome the diffraction limit and allowed direct optical imaging of structures below 100 nm without the aid of fluorescent microscopy. To allow imaging of specific areas on the surface of samples, the migration of the microspheres to specific locations on two-dimensional (2D) planes should be controlled to be as precise as possible. The common approach involves the attachment of microspheres on the tip of a probe. However, this technology requires additional space for the probe and could not work in an enclosed environment, e.g., in a microfluidic enclosure, thereby, reducing the range of potential applications for microlens-based super-resolution imaging. Herein, we explore the use of laser trapping to manipulate microspheres to achieve super-resolution imaging in an enclosed microfluidic environment. We have demonstrated that polystyrene microsphere lenses could be manipulated to move along designated routes to image features which are smaller than the optical diffraction limit. For example, a silver nanowire (AgNW) with a diameter of 90 nm could be identified and imaged. In addition, a mosaic image could be constructed by fusing a sequence of images of a sample in an enclosed environment. Moreover, we have shown that it is possible to image with this method Escherichia coli bacteria attached on the surface of an enclosed microfluidic device. This technology is expected to provide additional super-resolution imaging opportunities in enclosed environments, including microfluidic, lab-on-a-chip, and organ-on-a-chip devices.

    View details for DOI 10.1016/j.bpj.2020.10.032

    View details for PubMedID 33189683

  • Advancing nanomedicine with cross-link functionalized nanoparticles for rapid excretion. Angewandte Chemie (International ed. in English) Dai, H., Ma, Z., Wang, F., Zhong, Y., Salazar, F., Li, J., Zhang, M., Ren, F., Wu, A. M. 2020

    Abstract

    Nanoparticles have been widely investigated for preclinical animal models as imaging, therapeutic or theranostic agent. However, a very limited number of nanoscale materials are approved for human use due to retention and toxicity concerns. Recent years have seen in vivo fluorescence imaging in the long end of the second near infrared window (NIR-IIb, 1,500-1,700 nm), affording deeper tissue penetration and higher imaging clarity owing to reduced light scattering and near-zero autofluorescence. Most NIR-IIb fluorophores are nanoparticle based probes with long retentionin the body. Here, we applied a novel cross-linked coating to functionalize core/shell lead sulfide/cadmium sulfide quantum dots (PbS/CdS QDs) emitting at ~1,600 nm. The coating was comprised of an amphiphilic polymer followed by three crosslinked amphiphilic polymeric layers (branched PEG-linear PAA-branched PEG, P 3 coating), imparting high biocompatibility and > 90% excretion of QDs within 2 weeks of intravenous administration. The P 3 -QDs were utilized for conjugation to an engineered anti-CD8 diabody to afford in vivo molecular imaging of CD8+ cytotoxic T lymphocytes (CTLs) in response to anti-PD-L1 therapy. Two-plex molecular imaging in combination with down-conversion Er nanoparticles was performed for real-time in vivo monitoring of PD-L1+tumor cells and CD8+CTLswith cellular resolution by non-invasive NIR-IIb light sheet microscopy (LSM). In another application, angiogenesis in the tumor microenvironment was imaged with P 3 -QDs conjugated to TRC105, a chimeric monoclonal antibody against CD105. Further, P 3 -QDs afforded imaging of lymph nodes deep in the body with a signal-to-background ratio of up to ~170. Lastly, we show that the P 3 coating on magnetic nanoparticles also afforded rapid excretion in < 2 weeks, establishing generality of the approach. The ability of eliminating various nanoparticles from a body opens up many possibilities of nanomedicine for human use.

    View details for DOI 10.1002/anie.202008083

    View details for PubMedID 32681553

  • Enhanced high-quality super-resolution imaging in air using microsphere lens groups OPTICS LETTERS Luo, H., Yu, H., Wen, Y., Zhang, T., Li, P., Wang, F., Liu, L. 2020; 45 (11): 2981–84

    Abstract

    Most microsphere-assisted super-resolution imaging experiments require a high-refractive-index microsphere to be immersed in a liquid to improve the super-resolution. However, samples are inevitably polluted by residuals in the liquid. This Letter presents a novel (to the best of our knowledge) method employing a microsphere lens group (MLG) that can easily achieve high-quality super-resolution imaging in air. The performance of this method is at par or better than that of the high-refractive-index microspheres immersed in liquid. In addition, the MLG generates a real image that is closely related to the photonic nanojet position of the microsphere super-lens. This imaging method is beneficial in microsphere imaging applications where liquids are impractical.

    View details for DOI 10.1364/OL.393041

    View details for Web of Science ID 000537763300009

    View details for PubMedID 32479438

  • Fabrication of flexible microlens arrays for parallel super-resolution imaging APPLIED SURFACE SCIENCE Zhang, T., Li, P., Yu, H., Wang, F., Wang, X., Yang, T., Yang, W., Li, W. J., Wang, Y., Liu, L. 2020; 504
  • Microsphere-Based Super-Resolution Imaging for Visualized Nanomanipulation. ACS applied materials & interfaces Zhang, T. n., Yu, H. n., Li, P. n., Wang, X. n., Wang, F. n., Shi, J. n., Liu, Z. n., Yu, P. n., Yang, W. n., Wang, Y. n., Liu, L. n. 2020

    Abstract

    Nanomanipulation provides high operating accuracy and has been successfully applied in many fields such as nanoparticle assembly, nanowire alignment, and semiconductor device manufacturing. However, because of the limits of optical diffraction, the use of nanomanipulation is challenged by a lack of visual feedback at the nanoscale, and thus, its efficiency is difficult to be improved. In this study, we developed a novel method of microlens-enhanced nanomanipulation capable of real-time super-resolution imaging. Nanomanipulation was performed using the atomic force microscopy (AFM) mechanism by coupling a microlens to an AFM probe, and optical imaging with a minimum characteristic size of 80 nm is realized by combining the microlens with the optical imaging system. Under the conditions of fluorescent illumination and white light illumination, nanomanipulations were achieved under real-time visual guidance for fluorescent nanoparticles with a diameter of 100 nm and silver nanowires with a diameter of 80 nm, respectively. This method enables the possibility of in situ observation and manipulation, which can potentially be used for biological samples.

    View details for DOI 10.1021/acsami.0c12126

    View details for PubMedID 32960563

  • In vivo molecular imaging for immunotherapy using ultra-bright near-infrared-IIb rare-earth nanoparticles. Nature biotechnology Zhong, Y., Ma, Z., Wang, F., Wang, X., Yang, Y., Liu, Y., Zhao, X., Li, J., Du, H., Zhang, M., Cui, Q., Zhu, S., Sun, Q., Wan, H., Tian, Y., Liu, Q., Wang, W., Garcia, K. C., Dai, H. 2019

    Abstract

    The near-infrared-IIb (NIR-IIb) (1,500-1,700nm) window is ideal for deep-tissue optical imaging in mammals, but lacks bright and biocompatible probes. Here, we developed biocompatible cubic-phase (alpha-phase) erbium-based rare-earth nanoparticles (ErNPs) exhibiting bright downconversion luminescence at ~1,600nm for dynamic imaging of cancer immunotherapy in mice. We used ErNPs functionalized with cross-linked hydrophilic polymer layers attached to anti-PD-L1 (programmed cell death-1 ligand-1) antibody for molecular imaging of PD-L1 in a mouse model of colon cancer and achieved tumor-to-normal tissue signal ratios of ~40. The long luminescence lifetime of ErNPs (~4.6ms) enabled simultaneous imaging of ErNPs and lead sulfide quantum dots emitting in the same ~1,600nm window. In vivo NIR-IIb molecular imaging of PD-L1 and CD8 revealed cytotoxic T lymphocytes in the tumor microenvironment in response to immunotherapy, and altered CD8 signals in tumor and spleen due to immune activation. The cross-linked functionalization layer facilitated 90% ErNP excretion within 2weeks without detectable toxicity in mice.

    View details for DOI 10.1038/s41587-019-0262-4

    View details for PubMedID 31570897

  • Imaging with Optogenetically Engineered Living Cells as a Photodetector ADVANCED BIOSYSTEMS Li, G., Wang, F., Yang, W., Wang, W., Li, G., Wang, Y., Liu, L. 2019; 3 (8)
  • Development of an image biosensor based on an optogenetically engineered cell for visual prostheses. Nanoscale Li, G., Wang, F., Yang, W., Yang, J., Wang, Y., Wang, W., Liu, L. 2019

    Abstract

    Visual prostheses provide blind patients with artificial vision via electrical stimulation of surviving visual cells resulting in partial restoration of vision in many patients. However, high-resolution visual perception, long-term biocompatibility and safety remain the significant challenges of existing visual prostheses. Here, we present a novel method to develop a new visual prosthesis using living cells as integrated electronics and implantable microelectrodes. The living cells modified with channelrhodopsin-2 showed excellent light-sensitive properties and encoded image information with cellular deformations triggered by light stimulation. The photoresponsive properties of the cells were determined using a single pixel imaging system, which indicated that the cells can act as a good light-sensitive biosensor. Additionally, the imaging feasibility of the cells was further validated through successful and clear imaging of several object scenes using the same system. This work represents a step toward the design and use of living cells as an image biosensor for the development of a new generation of high-resolution visual prostheses.

    View details for DOI 10.1039/c9nr01688k

    View details for PubMedID 31184360

  • Light-sheet microscopy in the near-infrared II window NATURE METHODS Wang, F., Wan, H., Ma, Z., Zhong, Y., Sun, Q., Tian, Y., Qu, L., Du, H., Zhang, M., Li, L., Ma, H., Luo, J., Liang, Y., Li, W., Hong, G., Liu, L., Dai, H. 2019; 16 (6): 545-+
  • Molecular Imaging in the Second Near-Infrared Window ADVANCED FUNCTIONAL MATERIALS Wan, H., Du, H., Wang, F., Dai, H. 2019; 29 (25)
  • Light-sheet microscopy in the near-infrared II window. Nature methods Wang, F., Wan, H., Ma, Z., Zhong, Y., Sun, Q., Tian, Y., Qu, L., Du, H., Zhang, M., Li, L., Ma, H., Luo, J., Liang, Y., Li, W. J., Hong, G., Liu, L., Dai, H. 2019

    Abstract

    Non-invasive deep-tissue three-dimensional optical imaging of live mammals with high spatiotemporal resolution is challenging owing to light scattering. We developed near-infrared II (1,000-1,700nm) light-sheet microscopy with excitation and emission of up to approximately 1,320nm and 1,700nm, respectively, for optical sectioning at a penetration depth of approximately 750mum through live tissues without invasive surgery and at a depth of approximately 2mm in glycerol-cleared brain tissues. Near-infrared II light-sheet microscopy in normal and oblique configurations enabled in vivo imaging of live mice through intact tissue, revealing abnormal blood flow and T-cell motion in tumor microcirculation and mapping out programmed-death ligand 1 and programmed cell death protein 1 in tumors with cellular resolution. Three-dimensional imaging through the intact mouse head resolved vascular channels between the skull and brain cortex, and allowed monitoring of recruitment of macrophages and microglia to the traumatic brain injury site.

    View details for PubMedID 31086342

  • In situ printing of liquid superlenses for subdiffraction-limited color imaging of nanobiostructures in nature MICROSYSTEMS & NANOENGINEERING Jia, B., Wang, F., Chan, H., Zhang, G., Li, W. 2019; 5
  • Molecular imaging in the second near-infrared window. Advanced functional materials Wan, H. n., Du, H. n., Wang, F. n., Dai, H. n. 2019; 29 (25)

    Abstract

    In the past decade, noticeable progress has been achieved regarding fluorescence imaging in the second near-infrared (NIR-II) window. Fluorescence imaging in the NIR-II window demonstrates superiorities of deep tissue penetration and high spatial and temporal resolution, which are beneficial for profiling physiological processes. Meanwhile, molecular imaging has emerged as an efficient tool to decipher biological activities on the molecular and cellular level. Extending molecular imaging into the NIR-II window would enhance the imaging performance, providing more detailed and accurate information of the biological system. In this progress report, selected achievements made in NIR-II molecular imaging are summarized. The organization of this report is based on strategies underlying rational designs of NIR-II imaging probes and their applications in molecular imaging are highlighted. This progress report may provide guidance and reference for further development of functional NIR-II probes designed for high-performance molecular imaging.

    View details for DOI 10.1002/adfm.201900566

    View details for PubMedID 31885529

    View details for PubMedCentralID PMC6934177

  • Imaging with Optogenetically Engineered Living Cells as a Photodetector. Advanced biosystems Li, G. n., Wang, F. n., Yang, W. n., Wang, W. n., Li, G. n., Wang, Y. n., Liu, L. n. 2019; 3 (8): e1800319

    Abstract

    Biosyncretic systems integrating biological components with electromechanical devices have recently become a promising technology, in which biological components are used as actuators or sensing elements with higher-level performance than artificial systems. Here, a biosyncretic imaging system using an optogenetically engineered living cell as a photodetector is shown. The photoresponsive properties of the cell, such as spectrum and response range, dynamic characteristics, are measured and indicate that the cell functions as an excellent photodetector. In the system, the cell is directly utilized to generate light-triggered ionic currents, which encode the spatial image information and therefore are used to reconstruct the scenes under the view based on compressive sensing. Imaging with the cell-based photodetector is successfully performed by acquiring high-definition images using the system. The system also displays function superiority to a commercial photodiode, such as wider dynamic responsivity range. This work represents a step toward directly imaging with living materials and paves a new road for the development of future on-body bionic devices.

    View details for DOI 10.1002/adbi.201800319

    View details for PubMedID 32648700

  • Photonic Nanojet Sub-Diffraction Nano-Fabrication With in situ Super-Resolution Imaging IEEE TRANSACTIONS ON NANOTECHNOLOGY Wen, Y., Yu, H., Zhao, W., Wang, F., Wang, X., Liu, L., Li, W. 2019; 18: 226–33
  • In situ printing of liquid superlenses for subdiffraction-limited color imaging of nanobiostructures in nature. Microsystems & nanoengineering Jia, B. n., Wang, F. n., Chan, H. n., Zhang, G. n., Li, W. J. 2019; 5: 1

    Abstract

    The nanostructures and patterns that exist in nature have inspired researchers to develop revolutionary components for use in modern technologies and our daily lives. The nanoscale imaging of biological samples with sophisticated analytical tools, such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM), has afforded a precise understanding of structures and has helped reveal the mechanisms contributing to the behaviors of the samples but has done so with the loss of photonic properties. Here, we present a new method for printing biocompatible "superlenses" directly on biological objects to observe subdiffraction-limited features under an optical microscope in color. We demonstrate the nanoscale imaging of butterfly wing scales with a super-resolution and larger field-of-view (FOV) than those of previous dielectric microsphere techniques. Our approach creates a fast and flexible path for the direct color observation of nanoscale biological features in the visible range and enables potential optical measurements at the subdiffraction-limited scale.

    View details for PubMedID 31057928

    View details for PubMedCentralID PMC6330505

  • Developing a Bright NIR-II Fluorophore with Fast Renal Excretion and Its Application in Molecular Imaging of Immune Checkpoint PD-L1 ADVANCED FUNCTIONAL MATERIALS Wan, H., Ma, H., Zhu, S., Wang, F., Tian, Y., Ma, R., Yang, Q., Hu, Z., Zhu, T., Wang, W., Ma, Z., Zhang, M., Zhong, Y., Sun, H., Liang, Y., Dai, H. 2018; 28 (50)
  • Bright quantum dots emitting at 1,600 nm in the NIR-IIb window for deep tissue fluorescence imaging. Proceedings of the National Academy of Sciences of the United States of America Zhang, M., Yue, J., Cui, R., Ma, Z., Wan, H., Wang, F., Zhu, S., Zhou, Y., Kuang, Y., Zhong, Y., Pang, D., Dai, H. 2018; 115 (26): 6590–95

    Abstract

    With suppressed photon scattering and diminished autofluorescence, in vivo fluorescence imaging in the 1,500- to 1,700-nm range of the near-IR (NIR) spectrum (NIR-IIb window) can afford high clarity and deep tissue penetration. However, there has been a lack of NIR-IIb fluorescent probes with sufficient brightness and aqueous stability. Here, we present a bright fluorescent probe emitting at 1,600 nm based on core/shell lead sulfide/cadmium sulfide (CdS) quantum dots (CSQDs) synthesized in organic phase. The CdS shell plays a critical role of protecting the lead sulfide (PbS) core from oxidation and retaining its bright fluorescence through the process of amphiphilic polymer coating and transferring to water needed for imparting aqueous stability and compatibility. The resulting CSQDs with a branched PEG outer layer exhibited a long blood circulation half-life of 7 hours and enabled through-skin, real-time imaging of blood flows in mouse vasculatures at an unprecedented 60 frames per second (fps) speed by detecting 1,600-nm fluorescence under 808-nm excitation. It also allowed through-skin in vivo confocal 3D imaging of tumor vasculatures in mice with an imaging depth of 1.2 mm. The PEG-CSQDs accumulated in tumor effectively through the enhanced permeation and retention effect, affording a high tumor-to-normal tissue ratio up to 32 owing to the bright 1,600-nm emission and nearly zero autofluorescence background resulting from a large 800-nm Stoke's shift. The aqueous-compatible CSQDs are excreted through the biliary pathway without causing obvious toxicity effects, suggesting a useful class of 1,600-nm emitting probes for biomedical research.

    View details for PubMedID 29891702

  • Visible light induced electropolymerization of suspended hydrogel bioscaffolds in a microfluidic chip BIOMATERIALS SCIENCE Li, P., Yu, H., Liu, N., Wang, F., Lee, G., Wang, Y., Liu, L., Li, W. 2018; 6 (6): 1371–78

    Abstract

    The development of microengineered hydrogels co-cultured with cells in vitro could advance in vivo bio-systems in both structural complexity and functional hierarchy, which holds great promise for applications in regenerative tissues or organs, drug discovery and screening, and bio-sensors or bio-actuators. Traditional hydrogel microfabrication technologies such as ultraviolet (UV) laser or multiphoton laser stereolithography and three-dimensional (3D) printing systems have advanced the development of 3D hydrogel micro-structures but need either expensive and complex equipment, or harsh material selection with limited photoinitiators. Herein, we propose a simple and flexible hydrogel microfabrication method based on a ubiquitous visible-light projection system combined with a custom-designed photosensitive microfluidic chip, to rapidly (typically several to tens of seconds) fabricate various two-dimensional (2D) hydrogel patterns and 3D hydrogel constructs. A theoretical layer-by-layer model that involves continuous polymerizing-delaminating-polymerizing cycles is presented to explain the polymerization and structural formation mechanism of hydrogels. A large area of hydrogel patterns was efficiently fabricated without the usage of costly laser systems or photoinitiators, i.e., a stereoscopic mesh-like hydrogel network with intersecting hydrogel micro-belts was fabricated via a series of dynamic-changing digital light projections. The pores and gaps of the hydrogel network are tunable, which facilitates the supply of nutrients and discharge of waste in the construction of 3D thick bio-models. Cell co-culture experiments showed the effective regulation of cell spreading by hydrogel scaffolds fabricated by the new method presented here. This visible light enabled hydrogel microfabrication method may provide new prospects for designing cell-based units for advanced biomedical studies, e.g., for 3D bio-models or bio-actuators in the future.

    View details for DOI 10.1039/c7bm01153a

    View details for Web of Science ID 000433604100007

    View details for PubMedID 29790875

  • Developing a Bright NIR-II Fluorophore with Fast Renal Excretion and Its Application in Molecular Imaging of Immune Checkpoint PD-L1. Advanced functional materials Wan, H. n., Ma, H. n., Zhu, S. n., Wang, F. n., Tian, Y. n., Ma, R. n., Yang, Q. n., Hu, Z. n., Zhu, T. n., Wang, W. n., Ma, Z. n., Zhang, M. n., Zhong, Y. n., Sun, H. n., Liang, Y. n., Dai, H. n. 2018; 28 (50)

    Abstract

    Fluorescence imaging in the second near-infrared (NIR-II) window holds impressive advantages of enhanced penetration depth and improved signal-to-noise ratio. Bright NIR-II fluorophores with renal excretion ability and low tissue accumulation are favorable for in vivo molecular imaging applications as they can render the target-mediated molecular imaging process easily distinguishable. Here, a probe (anti-PD-L1-BGP6) comprising a fluorophore (IR-BGP6) covalently bonded to the programmed cell death ligand-1 monoclonal antibody (PD-L1 mAb) for molecular imaging of immune checkpoint PD-L1 (a targeting site upregulated in various tumors for cancer imaging) in the NIR-II window is reported. Through molecular optimization, the bright NIR-II fluorophore IR-BGP6 with fast renal excretion (≈91% excretion in general through urine within the first 10 h postinjection) is developed. The conjugate anti-PD-L1-BGP6 succeeds in profiling PD-L1 expression and realizes efficient noninvasive molecular imaging in vivo, achieving a tumor to normal tissue (T/NT) signal ratio as high as ≈9.5. Compared with the NIR-II fluorophore with high nonspecific tissue accumulation, IR-BGP6 derived PD-L1 imaging significantly enhances the molecular imaging performance, serving as a strong tool for potentially studying underlying mechanism of immunotherapy. The work provides rationales to design renal-excreted NIR-II fluorophores and illustrate their advantages for in vivo molecular imaging.

    View details for DOI 10.1002/adfm.201804956

    View details for PubMedID 31832053

    View details for PubMedCentralID PMC6907024

  • Scanning superlens microscopy for non-invasive large field-of-view visible light nanoscale imaging NATURE COMMUNICATIONS Wang, F., Liu, L., Yu, H., Wen, Y., Yu, P., Liu, Z., Wang, Y., Li, W. 2016; 7: 13748

    Abstract

    Nanoscale correlation of structural information acquisition with specific-molecule identification provides new insight for studying rare subcellular events. To achieve this correlation, scanning electron microscopy has been combined with super-resolution fluorescent microscopy, despite its destructivity when acquiring biological structure information. Here we propose time-efficient non-invasive microsphere-based scanning superlens microscopy that enables the large-area observation of live-cell morphology or sub-membrane structures with sub-diffraction-limited resolution and is demonstrated by observing biological and non-biological objects. This microscopy operates in both non-invasive and contact modes with ∼200 times the acquisition efficiency of atomic force microscopy, which is achieved by replacing the point of an atomic force microscope tip with an imaging area of microspheres and stitching the areas recorded during scanning, enabling sub-diffraction-limited resolution. Our method marks a possible path to non-invasive cell imaging and simultaneous tracking of specific molecules with nanoscale resolution, facilitating the study of subcellular events over a total cell period.

    View details for DOI 10.1038/ncomms13748

    View details for Web of Science ID 000389537800001

    View details for PubMedID 27934860

    View details for PubMedCentralID PMC5476830