Gold Nanoparticles‐Based DNA Logic Gate for miRNA Inputs Analysis Coupling Strand Displacement Reaction and Hybridization Chain Reaction

The molecular level DNA logic gates assisted by nanomaterials hold great promise for disease diagnosis applications. However, designing convenient and sensitive logic gates for molecular diagnostics still remains challenging. In this work, a DNA logic gate platform for miRNA inputs analysis based on the observation of localized surface plasmon resonance variation of gold nanoparticles (AuNPs) is fabricated. As a demonstration, two biomarkers to differentiate indolent and aggressive forms of prostate cancer, miR‐200c and miR‐605, are selected as examples of logical inputs. In addition, five DNA probes are designed according to strand displacement reaction and hybridization chain reaction which are required for DNA logical operation. Since target miRNA inputs are able to trigger DNA structural transformations, which are further used to precisely regulate salt‐induced AuNPs aggregation, miRNA inputs information can be converted to the information of AuNPs states as outputs. This developed system performs amplified detection of low‐abundant target miRNAs without the requirement of any enzymes. In addition, single base‐pair mismatched miRNAs can be effectively differentiated. High‐order logic gates can also be developed with further modifications. Therefore, the DNA AND logic gate is successfully constructed with flexible operations, which has potential in biochemical study and disease diagnosis.     

Fluorescence Turn-On Analysis of Trace Protein Based on Carbon Nanodots and Hybridization Chain Reaction

In this work, an ultrasensitive method for trace protein detection based on fluorescent carbon nanodots and hybridization chain reaction (HCR) is designed. Generally, the synthesized bright carbon nanodots are conjugated with two hairpin-structured DNA probes, respectively, which act as subsequent HCR fuel strands. Since single-stranded parts of DNA probes could be easily absorbed on graphene oxide (GO) nanosheets, fluorescence emission of carbon nanodots is effectively quenched via fluorescence resonance energy transfer. However, in the presence of target protein, the aptamer sequence in another hairpin-structured DNA probe specially interacts with target and the hairpin is opened. A single-stranded region is thus exposed, which initiates HCR by coupling with the DNA fuel strands on carbon nanodots. The formed HCR product displays a rigid, long double-stranded structure, which facilitates the release of carbon nanodots from GO surface. As a result, fluorescence of carbon nanodots is recovered and initial concentration of target protein can be estimated. This protein detection method shows a favorable linear response with a low limit of detection (2.3 fg mL⁻¹). Furthermore, it is highly selective and capable of detecting target in biological fluids like serum samples, which demonstrates the promising applications of this method.     

基于光谱成像技术的宫颈癌TBS与细胞DNA定量分析联合筛查方法研究

传统的宫颈癌筛查方法主要有TBS分类筛查法和基于细胞DNA的定量分析筛查法,TBS分类筛查法诊断率高但需要经验丰富的医生参与且敏感度低,难以实现宫颈癌早期筛查;基于细胞DNA的定量分析筛查法仅染色细胞核,实现了定量化与自动化分析,敏感度高但特异性差。因此实现宫颈癌TBS与DNA定量分析联合筛查十分必要,但目前TBS与DNA定量分析联合筛查方法均是使用两张不同的细胞涂片分别进行,费时费力费材极为不便,国内外还没有在一张宫颈细胞涂片上联合使用这两种方法的宫颈癌筛查方法。为此提出了一种在一张细胞涂片上同时使用TBS分类法和细胞DNA定量分析法的宫颈癌筛查方法:在同一张细胞涂片上对细胞进行巴氏染色和Feulgen染色,为解决多重染色带来的DNA物质的吸光度干扰问题,建立一套多光谱成像系统,并提出基于线性多元回归的DNA吸光度剥离模型,通过该模型解算出DNA物质的真实吸光度从而实现DNA物质的定量分析;选取接近RGB波长的3个波段细胞图像合成伪彩色图像进行TBS分类筛查。实现了一张细胞涂片上的宫颈癌TBS与DNA定量分析联合筛查,DNA定量分析模型稳定度高、误差小,诊断率高,用于TBS筛查的伪彩色图像颜色明亮、细胞核清晰可见、细胞质边缘明确,该方法在宫颈癌的诊断和筛查中具有很强的实用性。     

Sulfur Immobilized in Hierarchically Porous Structured Carbon as Cathodes for Lithium–Sulfur Battery with Improved Electrochemical Performance

In order to overcome the main obstacles for lithium–sulfur batteries, such as poor conductivity of sulfur, polysulfide intermediate dissolution, and large volume change generated during the cycle process, a hard‐template route is developed to synthesize large‐surface area carbon with abundant micropores and mesopores to immobilize sulfur species. The microstructures of the C/S hybrids are investigated using field emission scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, Raman spectroscopy, X‐ray photoelectron spectroscopy, nitrogen adsorption–desorption isotherms, and electrochemical impedance spectroscopy techniques. The large surface and porous structure can effectively alleviate large strain due to the lithiation/delithiation process. More importantly, the micropores can effectively confine small molecules of sulfur in the form of S_2–4, avoiding loss of active S species and dissolution of high‐order lithium polysulfides. The porous C/S hybrids show significantly enhanced electrochemical performance with good cycling stability, high specific capacity, and rate capability. The C/S‐39 hybrid with an optimal content of 39 wt% S shows a reversible capacity of 780 mA h g^?1 after 100 cycles at the current density of 100 mA g^?1. Even at a current density of 5 A g^?1, the reversible capacity of C/S‐39 can still maintain at 420 mA h g^?1 after 60 cycles. This strategy offers a new way for solving long‐term reversibility obstacle and designing new cathode electrode architectures.