About

Ji-Xin Cheng is a Professor and Affiliate Faculty in the Department of Physics at Boston University, with a focus on molecular spectroscopic imaging. His research develops and applies advanced imaging technologies to enable discovery-driven research aimed at marker-based precise diagnosis and treatment of human diseases. His work integrates expertise across engineering, physics, chemistry, biology, medicine, and entrepreneurship, and is devoted to the development of imaging tools, discovery of new biological insights, and clinical translation. Professor Cheng's research encompasses several cutting-edge projects, including multiplex stimulated Raman microscopy, mid-infrared photothermal microscopy that breaks the diffraction limit, vibration-based photoacoustic tomography, transient absorption microscopy, and volumetric chemical microscopy for label-free chemical histology. His contributions have advanced the field of molecular spectroscopic imaging, with significant implications for biology and medicine. He holds a B.S. in Chemical Physics and a Ph.D. from the University of Science and Technology of China.

Research topics

• Chemistry
• Nanotechnology
• Optics
• Materials science
• Remote sensing
• Physical chemistry
• Inorganic chemistry
• Molecular physics
• Physics
• Optoelectronics

Selected publications

• Gap-enhanced gold nanodumbbells with single-particle surface-enhanced Raman scattering sensitivity

  RSC Advances · 2023 · 6 citations

  • Materials science
  • Nanotechnology
  • Chemistry

  Gap-enhanced Raman tags (GERTs) have been widely used for surface-enhanced Raman scattering (SERS) imaging due to their excellent SERS performances. Here, we reported a synthetic strategy for novel gap-enhanced dumbbell-like nanoparticles with anisotropic shell coatings. Controlled shell growth at the tips of gold nanorods was achieved by using cetyltrimethylammonium bromide (CTAB) as a capping agent. A mechanism related to the shape-directing effects of CTAB was proposed to explain the findings. Optimized gap-enhanced gold dumbbells exhibited highly enhanced SERS responses compared to rod cores, with an enhancement ratio of 101.5. We further demonstrated that gap-enhanced AuNDs exhibited single-particle SERS sensitivity with an acquisition time as fast as 0.1 s per spectrum, showing great potential for high-speed SERS imaging.

  DOI

• Vibrational Spectroscopic Detection of a Single Virus by Mid-Infrared Photothermal Microscopy

  Analytical Chemistry · 2021 · 59 citations

  • Chemistry
  • Biophysics
  • Nanotechnology

  We report a confocal interferometric mid-infrared photothermal (MIP) microscope for ultra-sensitive and spatially resolved chemical imaging of individual viruses. The interferometric scattering principle is applied to detect the very weak photothermal signal induced by infrared absorption of chemical bonds. Spectroscopic MIP detection of single vesicular stomatitis viruses (VSVs) and poxviruses is demonstrated. The single virus spectra show high consistency within the same virus type. The dominant spectral peaks are contributed by the amide I and amide II vibrations attributed to the viral proteins. The ratio of these two peaks is significantly different between VSVs and poxviruses, highlighting the potential of using interferometric MIP microscopy for label-free differentiation of viral particles. This all-optical chemical imaging method opens a new way for spectroscopic detection of biological nanoparticles in a label-free manner and may facilitate in predicting and controlling the outbreaks of emerging virus strains.

  DOI

• Interaction of tau with HNRNPA2B1 and N6-methyladenosine RNA mediates the progression of tauopathy

  Molecular Cell · 2021 · 189 citations

  • Biology
  • Cell biology
  • Biochemistry
  PublisherOA PDFDOI

• Optoacoustic brain stimulation at submillimeter spatial precision

  Nature Communications · 2020 · 90 citations

  • Computer Science
  • Neuroscience
  • Physics

  transients. The FOC activates neurons within a radius of 500 μm around the fiber tip, delivering superior spatial resolution over conventional piezo-based low-frequency transducers. Finally, we demonstrate direct and spatially confined neural stimulation of mouse brain and modulation of motor activity in vivo.

  DOI

• Functionalized NIR‐II Semiconducting Polymer Nanoparticles for Single‐cell to Whole‐Organ Imaging of PSMA‐Positive Prostate Cancer

  Small · 2020 · 40 citations

  • Materials science
  • Biomedical engineering
  • Cancer research

  Development of molecular probes holds great promise for early diagnosis of aggressive prostate cancer. Here, 2-[3-(1,3-dicarboxypropyl) ureido] pentanedioic acid (DUPA)-conjugated ligand and bis-isoindigo-based polymer (BTII) are synthesized to formulate semiconducting polymer nanoparticles (BTII-DUPA SPN) as a prostate-specific membrane antigen (PSMA)-targeted probe for prostate cancer imaging in the NIR-II window. Insights into the interaction of the imaging probes with the biological targets from single cell to whole organ are obtained by transient absorption (TA) microscopy and photoacoustic (PA) tomography. At single-cell level, TA microscopy reveals the targeting efficiency, kinetics, and specificity of BTII-DUPA SPN to PSMA-positive prostate cancer. At organ level, PA tomographic imaging of BTII-DUPA SPN in the NIR-II window demonstrates superior imaging depth and contrast. By intravenous administration, BTII-DUPA SPN demonstrates selective accumulation and retention in the PSMA-positive tumor, allowing noninvasive PA detection of PSMA overexpressing prostate tumors in vivo. The distribution of nanoparticles inside the tumor tissue is further analyzed through TA microscopy. These results collectively demonstrate BTII-DUPA SPN as a promising probe for prostate cancer diagnosis by PA tomography.

  DOI

• Origin of dispersive line shapes in plasmon‐enhanced stimulated Raman scattering microscopy

  Nanophotonics · 2020 · 10 citations

  Senior authorCorresponding
  • Materials science
  • Molecular physics
  • Optics

  Abstract Plasmon‐enhanced stimulated Raman scattering (PESRS) microscopy has been recently developed to reach single‐molecule detection limit. Unlike conventional stimulated Raman spectra, dispersive‐like vibrational line shapes were observed in PESRS. Here, we propose a theoretical model together with a phasor diagram to explain the observed dispersive‐like line shapes reported in our previous study. We show that the local enhanced electromagnetic field induced by the plasmonic nanostructure interferes with the molecular dipole‐induced field, resulting in the dispersive profiles of PESRS. The exact shape of the profile depends on the phase difference between the plasmonic field and the molecular dipole field. We compared plasmon‐enhanced stimulated Raman loss (PESRL) and plasmon‐enhanced stimulated Raman gain (PESRG) signals under the same pump and Stokes laser wavelength. The PESRL and PESRG signals exhibit similar signal magnitudes, whereas their spectral line shapes show reversed dispersive profiles, which is in an excellent agreement with our theoretical prediction. Meanwhile, we verify that the nonresonant background in PESRS mainly originates from the photothermal effect. These new insights help the proper use of PESRS for nanoscale bio‐imaging and ultrasensitive detection.

  DOI

• Real-time imaging of surface chemical reactions by electrochemical photothermal reflectance microscopy

  Chemical Science · 2020 · 3 citations

  Senior authorCorresponding
  • Materials science
  • Nanotechnology
  • Chemistry

  Traditional electrochemical measurements based on either current or potential responses only present the average contribution of an entire electrode's surface. Here, we present an electrochemical photothermal reflectance microscope (EPRM) in which a potential-dependent nonlinear photothermal signal is exploited to map an electrochemical process with sub-micron spatial resolution. By using EPRM, we are able to monitor the photothermal signal of a Pt electrode during the electrochemical reaction at an imaging speed of 0.3 s per frame. The potential-dependent photothermal signal, which is sensitive to the free electron density, clearly revealed the evolution of surface species on the Pt surface. Our results agreed well with the reported spectroelectrochemical techniques under similar conditions but with a much faster imaging speed. We further mapped the potential oscillation during the oxidation of formic acid on the Pt surface. The photothermal images from the Pt electrode well matched the potential change. This technique opens new prospects for real-time imaging of surface chemical reaction to reveal the heterogeneity of electrochemical reactivity, which enables broad applications to the study of catalysis, energy storage, and light harvest systems.

  DOI

Recent grants

• NIH Grant R01EB007243

  NIH · $950k · 2011

• NIH Grant R21EB004966

  NIH · $403k · 2008

Frequent coauthors

• Cosme Furlong

  Worcester Polytechnic Institute

  14 shared

• John J. Rosowski

  Eaton (United States)

  11 shared

• Cheng Zong

  4 shared

• Susana Oliveira

  Worcester Polytechnic Institute

  3 shared

• Christopher W. Mullins

  3 shared

• Lucas D. Reiniger

  Worcester Polytechnic Institute

  3 shared

• Brant W. Reymann

  Worcester Polytechnic Institute

  3 shared

• Jivan H. Purutyan

  Worcester Polytechnic Institute

  3 shared

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