A Small-Molecule Diketopyrrolopyrrole-Based Dye for in vivo NIR-IIa Fluorescence Bioimaging

Organic small-molecule fluorophores with near-infrared IIa (NIR-IIa) emission have great potential in pre-clinical detection and inoperative imaging due to the high-spatial resolution and deep penetration. However, developments of the NIR-IIa fluorophores are still facing considerable challenges. In this work, a series of diketopyrrolopyrrole (DPP)-based fluorophores were designed and synthesized. Subsequently, nanomaterial T25@F127 with significant NIR-IIa emission properties was rationally prepared by encapsulating DPP-based fluorophore T25 , and was selected for fluorescence angiography and cerebral vascular microscopic imaging with nearly 800 μm penetrating depth and excellent signal-background ratio of 4.07 and 2.26 (at 250 and 400 μm), respectively. Furthermore, the nanomaterial T25@cRGD with tumor targeting ability can image tiny metastatic tumor on intestine with a small size of 0.3 mm×1.0 mm and high-spatial resolution (SBR=3.84). This study demonstrates that the nanomaterials which encapsulated T25 behave as excellent NIR-IIa fluorescence imaging agents and have a great potential for in vivo biological application.     

Superiority of zoom lens coupling in designing a novel X-ray image detector

We design a novel X-ray image detector by lens coupling a Gd2O2S:Tb intensifying screen with a high performance low-light-level (L3,which often means luminescence less than 10-3 Lux) image intensifier.Different coupling effects on imaging performance between zoom lens and fix-focus lens are analyzed theoretically.In experiment,for designing a detector of 15-inch visual field,the system coupled by zoom lens is of 12.25-1p/cm resolution,while the one with fix-focus lens is 10 lp/cm.The superiority of zoom lens is validated.It is concluded that zoom lens preserves the image information better than fix-focus lens and improves the imaging system's performance in this design,which is referential to the design of other optical imaging systems.     

基于坐标变换的动态光学成像性质研究

利用齐次线性坐标变换，将光学系统的高斯物像共轭理论用齐次坐标变换的方法来描述，并与动态光学理论中的作用矩阵相比较，阐述坐标变换方法与动态光学理论的关系。利用坐标变换方法推导一些重要的动态光学系统的成像性质，验证动态光学的一系列结论。通过本文的研究，证明坐标变换方法与动态光学理论的一致性，也明确在动态光学系统内坐标变换方法的应用。     

Study on a hidden protein-DNA binding in salmon sperm DNA sample by dynamic kinetic capillary isoelectric focusing

Nuclease P1 is an important enzyme that hydrolyzes RNA or single-stranded DNA into nucleotides, and complete digestion is an essential basis for assays based on this enzyme. To digest a doubled-stranded DNA, the enzyme is usually combined with heat denaturing, which breaks doubled-stranded DNA into single strands. This paper presents an un-expected phenomenon that nuclease P1, in combination with heat denaturing, fails to completely digest a DNA sample extracted from salmon sperm. Under the experimental conditions used, at which nuclease P1 can completely digest calf thymus DNA, the digestion yield of salmon sperm DNA was only 89.5%. Spectrometric measurement indicated that a total protein of 4.7% is present in the DNA sample. To explain the reason for this phenomenon, the dynamic kinetic capillary isoelectric focusing (DK-CIEF) approach proposed previously, which allows for the discrimination of different types of protein-DNA interactions and the measurement of the individual dissociation rate constants, was modified and applied to examine possible protein-DNA interactions involved. It was found that a non-specific DNA-protein binding occurs in the sample, the dissociation rate constant for which was measured to be 7.05 ± 0.83 × 10⁻³ s⁻¹. The formation of DNA-protein complex was suggested to be the main reason for the incomplete digestion of the DNA sample. The modified DK-CIEF approach can be applied as general DNA samples, with the advantages of fast speed and low sample consumption.     

A Molecular Brush Approach to Enhance Quantum Yield and Suppress Nonspecific Interactions of Conjugated Polyelectrolyte for Targeted Far‐Red/Near‐Infrared Fluorescence Cell Imaging

A red‐fluorescent conjugated polyelectrolyte (CPE, P2 ) is grafted with dense poly(ethylene glycol) (PEG) chains via click chemistry and subsequently modified with folic acid to form a molecular brush based cellular probe ( P4 ). P4 self‐assembles into a core–shell nanostructure in aqueous medium with an average size of 130 nm measured by laser light scattering. As compared to P2 , P4 possesses not only a substantially higher quantum yield (11%), but also reduced nonspecific interactions with biomolecules in aqueous medium due to the shielding effect of PEG. In conjunction with its high photostability and low cytotoxicity, utilization of P4 as a far‐red/near‐infrared cellular probe allows for effective visualization and discrimination of MCF‐7 cancer cells from NIH‐3T3 normal cells in a high contrast, selective, and nonviral manner. This study thus demonstrates a flexible molecular brush approach to overcome the intrinsic drawbacks of CPEs for advanced bioimaging applications.     

Mapping of elastic modulus at sub-micrometer scale with acoustic contact resonance AFM

Atomic Force Acoustic Microscopy (AFAM) is a powerful near field technique combining the high spatial resolution of Atomic Force Microscope (AFM) with ultrasonic stresses to access mechanical properties of material shallow surfaces (essentially local stiffness magnitudes like Young modulus). In this article, we discuss different experimental set-up and modelling approaches to determine quantitatively the Young modulus of thin films. Static experiments carried-out on dense and nanoporous silica have shown a good agreement with nanoindentation experiments. Stiffness mapping have also been performed on macroporous silica and copper interconnect structures, showing the ability of our set-up to sense different mechanical answers at sub-micrometer scale.     

应用角谱方法研究聚焦声束在层状生物组织中的非线性声传播

应用角谱方法理论研究了聚焦声束在层状生物组织中的非线性传播特性，将声波分解为角谱，可计算垂直于声轴的任意平面的非线性声场。在圆形平面活塞聚焦换能器的焦区中插入多种生物组织样品，数值计算了样品内部及外部的二次谐波声场，并通过实验测量验证了理论方法的有效性。基于快速傅氏变换的角谱方法可直观地描述非线性声传播，对非线性声成像有指导作用。     

主动成像系统距离选通实验方案设计

 距离选通技术是克服大气后向散射，提高主动成像系统信噪比的有效方法。分析了距离选通的技术要求，分别使用电源调制和机械调制的方法获得了适合用于主动成像系统脉冲光源,并进行了距离选通实验，机械调制方法适用于大功率连续半导体激光器。使用氙灯泵浦YAG激光器实现了对675 m和1 509 m距离目标的主动成像，详细分析了几种方案的利弊并提出了改进方法。