Confocal Laser Scanning Microscopy Based on a Silicon Photomultiplier for Multicolor In Vivo Imaging in Near‐Infrared Regions I and II

Abstract

Confocal laser scanning microscopy (CLSM) is expected to exhibit a better imaging performance in the second near‐infrared (NIR‐II) windows with weak tissue scattering and autofluorescence. However, the indium gallium arsenide (InGaAs) detectors currently used for imaging in the NIR‐II region are prohibitively expensive, hampering its extensive biomedical applications. In this study, a novel NIR‐II CLSM system is developed by using the inexpensive silicon photomultiplier (SiPM) that can perform the multicolor biological imaging in vivo. Using IR‐780 iodide as the contrast agent, the NIR‐II imaging capability of constructed CLSM is inspected, demonstrating a spatial resolution of 1.68 µm (close to the diffraction limit) and a fluorophore detection sensitivity as low as 100 nm. In particular, it is discovered that the multicolor imaging performance in both NIR‐I and NIR‐II windows is comparable to those from multialkali and InGaAs photomultiplier tubes. In addition, 3D NIR‐II CLSM is also conducted for in vivo imaging of the vascular structure in mouse ear and subcutaneous tumors. To the best of authors’ knowledge, this is the first time that a low‐cost detector based on a SiPM has been used for microscopic imaging of trailing fluorescence signals in the NIR‐II region of an NIR fluorescent probe.

Synergistic Phototherapy-Molecular Targeted Therapy Combined with Tumor Exosome Nanoparticles for Oral Squamous Cell Carcinoma Treatment

“…DiI and Hoechst 33,342 channels were used for the detection of DiI-labelled IG@EXOs and nuclei, respectively. The imaging process was conducted in LineSequential mode with AxioObserver as the microscope and Plan-Apochromat 20×/0.8 M27 as the objective lens with laser power set to 2.0%, according to the reported methods with modifications [ 28 , 29 ]. The CLSM used below was operated under the same conditions.…”

Integration of PbS Quantum Dots with 3D-Graphene for Self-powered Broadband Photodetectors in Image Sensors

“…Existing NIR PDs, exemplified by the InGaAs detector, have been applied in infrared civilian markets and military fields due to their adjustable band gap. However, the limited operating wavelength range (800 nm to 1.7 μm) and process shortcomings (difficult to prepare large size) have seriously hindered its performance and application expansion. , 3D-graphene, as a derivative of 2D-graphene, not only maintains the extraordinary properties of graphene, such as high electrical conductivity and wide-band photoresponse, but more importantly, its unique interlayer interconnecting structure greatly improves light absorption. − In addition, PbS QDs are also promising candidates for NIR photovoltaic applications owing to their straightforward solution processing, size-tunable bandgap, and excellent photovoltaic properties. , …”

Near-infrared dye IRDye800CW-NHS coupled to Trastuzumab for near-infrared II fluorescence imaging in tumor xenograft models of HER-2-positive breast cancer

“…5,6 Compared to conventional near infrared region I (NIR-I, 700-900 nm) imaging, NIR-II imaging offers higher signal-to-noise ratio, lower autofluorescence in organisms and deeper penetration, resulting in significantly improved oncology treatment efficacy. [7][8][9] At present, the NIR-II imaging technology is developing rapidly, yielding promising results and demonstrating successful applications in surgical guidance for oncology procedures. [10][11][12] Indocyanine green (ICG) is a small molecule dye that exhibits hepatic affinity for the NIR-I imaging.…”