第八屆全國微全分析系統學術會議微納米生物分析專場

　　2013年5月16日-19日，由中國化學會主辦、廈門大學承辦、復旦大學、浙江大學協辦的為期四天的第八屆全國微全分析系統學術會議、第三屆全國微納尺度生物分離分析學術會議暨第五屆國際微化學與微系統學術會議在美麗的海濱城市廈門隆重召開。以下是5月17日微納米生物分析專場報告。

南京大學 鞠熀先教授

　　首先來自南京大學的鞠熀先教授為我們帶來了題為《Signal amplification coupled with molecular recognition for biological analysis》的精彩報告，以下是摘要原文：

　　This talk will introduce a series of novel signal amplification strategies and their application in biosensing and biological analysis based on nanotechnology and molecular biological methods. The nanotechnology for signal amplification includes:

　　1) accelerating the electron transfer or obtaining sensitized optical signal, 2) catalyticand enzyme mimetic functions of the nanomaterials, 3) using nanomaterials as tag molecules, 4) using nanomaterials as the carriers of signaling molecules, 5) electrochemiluminescent or photoelectrochemical signal amplification, and 6) selective concentration of biomolecules by biorecognition. The molecular biological amplification is designed by introducing rolling circle amplification, target-induced repeated primer extension, hybridization chain reaction, loop-mediated amplification, target DNA recycling amplification such as endonuclease-, exonuclease- and polymerase-based circular strand replacement polymerization to amplify the electrochemical, optical and visual signals. The established methods can conveniently be used in the detections of small biomolecules, proteins, cells, the carbohydrate sites on cell surfaces and intracellular microRNA by electrochemical, optical, mass spectrometric, and imaging measurements.

廈門大學 任斌教授

　　來自廈門大學的任斌教授為我們帶來了題為《Plasmon-enhanced Raman Spectroscopy for Surface- and Bio-analysis》的精彩報告。以下是內容摘要。

　　Both surface-enhanced Raman spectroscopy (SERS) and tip-enhanced Raman spectroscopy (TERS) is benefited from the the localized surface plasmon resonance (LSPR) of metallic nanostructures. They can provide high sensitivity with molecular fingerprint information for ultratrace analysis, even down to single molecules. To take the challenge of using SERS for bioanalysis , we developed a method to modify the surface of SERS active nanoparticle colloids or solid SERS substrates with some halide ions. Proteins were found to interact with the modified substrate via electrostatic interaction. The SERS signal of protein is at least enhanced by 1000 time over the solution species, with almost identical feature to that of the solution signal of proteins. The methods have been applied to study the lysosome, BAS, avidin, hemoglobin, cytochrome c and etc. The detection limit for lysosome can be as low as 3 mg/mL. The ability to obtain SERS signal of protein with very good reproducibility and high sensitivity is extremely important to the wider application of SERS technique to biological systems. We further systematically study the methodology of using a probe molecule to monitor the local pH environment of live cells. It was found that it is vitally important to control the interfacial structure and measuring condition in order to obtain reliable pH response. On the other hand, TERS can not only provide very high sensitivity but also high spatial resolution, which is extremely important when it is used to study the dynamic processes on surfaces. The high spatial resolution allows the extraction of signals from the “some molecules” or even “single molecules” by significantly lowering the background averaged signal. Using thiols for example, we found that TERS can clearly provide the immersing time dependent of the self-assemble mononlayer, which is a reflection of the strong interaction between the thiol molecules. The dynamic diffusion process could be revealed by the combined two-dimensional and autocorrelation analyses.

南京大學化學化工學院 許丹科教授

　　來自南京大學化學化工學院的許丹科教授為我們帶來了題為《基于納米銀探針的微陣列芯片檢測方法的研究》的精彩報告，以下是內容摘要：

　　納米材料的功能化研究對于發展其在生物分析領域的應用具有重要作用。近年來，我們研究了納米銀的合成及功能化方法。通過巰基自組裝、親和素-生物素相互作用等途徑實現了納米銀表面的DNA 單鏈分子、適配體及蛋白質分子等的功能化修飾，采用研制的功能化納米銀分析材料建立了電化學檢測、熒光檢測及可視化檢測等多種微陣列芯片的分析方法。

　　以DNA 修飾的納米銀為生物功能探針、DNA 芯片為分析模式，開展了對多種病毒DNA片段的電化學信號放大檢測方法的研究，具有快速簡便、靈敏度高、可實現多靶標檢測等優點。開展了功能化納米銀熒光增強檢測方法的研究，研究了基于納米銀熒光增強機制的新型生物探針及基于聚合納米銀的金屬熒光增強檢測方法，利用Cy3 分子數量的增加及Cy3 發射光譜與納米銀聚合物表面等離子體共振峰的耦合作用放大熒光信號，實現對蛋白質的高靈敏檢測。此外，研究了適配體修飾的可視化納米銀生物探針檢測方法，將微孔板生物芯片技術與納米銀催化銀離子顯色方法結合，具有靈敏度高、操作簡單、結果可視化的優點。

　　研究內容揭示了功能化納米銀分析材料具有優良的生物兼容性，能成為DNA、蛋白質等多種生物分子識別的有效載體。納米銀本身顯示了良好的光電特性，為發展新型納米分析材料提供了新的發展方向。

材料科學與工程研究院 蘇曉迪教授

　　來自材料研究工程學院的蘇曉迪為我們帶來了題為《Hybrid Assembly of Gold Nanoparticles with Fluorescent Materials for Studying Protein-DNA Interaction and Ligand Inhibition》

　　Gold nanoparticles have unique optical properties arising from their ability to support localized surface plasmonc resonance. Gold nanoparticles are also well-known by their ability to alter the emission properties of proximal fluorophores, due to F?rster resonance energy transfer (FRET), nanomaterial surface energy transfer (NSET), or electron transfer, depending on the distance of the fluorophores to nanoparticle surface and the emission wavelength of the fluorophores. In previous studies, we have developed a series of metal nanoparticles based bioassays for studying various biomolecular binding events, concerning DNA mutation [1-3], gene transcription [4, 5], enzymatic cleavage of DNA, and aptamer selection [7], by exploiting interparticle distance determined plasmonic property. In this study we have combined gold nanoparticles’ fluorescence quenching properties and protein-DNA binding induced hybrid assembly between gold nanoparticles and fluorescent materials for efficient study of transcription factor-DNA interactions and ligand inhibition that are important for breast cancer research and drug discovery. The results are compared with those using conventional biological analysis methods, i.e. EMSA and fluorescence anisotropy, as well as instrument based methods (dual polarization interferometer and surface plasmon resonance spectroscopy). With the conventional methods as reference, we concluded that the gold nanoparticle-fluorophore hybrid sensors have higher sensitivity to determine subtle affinity difference induced by single base mutation in DNA elements and to report strong and weak ligand interruption. Understanding the DNA binding property and ligand effects of these transcription factors is of significant for breast cancer and drug discovery research.

南洋理工大學 楊毅教授

　　來自南洋理工大學的楊毅教授為我們帶來了題為《Microparticles Sorting by Hydrodynamic Optical Forces》的精彩報告，以下是報告摘要：

　　This paper reports a microfluidic microparticles sorting generator by using the optical force and hydrodynamic forces. Micro/Nanoparticles ranging in size from 70 nm to 1 μm can be aligned and focused in the core flow stream by hydrodynamic focusing [1-3]. The particles can be subsequently manipulated by the optical force and liquid stoke forces. The particles with different size and refractive indices can be selected by the optical forces and drag force, flowing with different traces. It has a great potential in cell, or molecule sorting and Separating.

　　 Figure 1 shows the schematic of the nano-optofluidic system, which consists of three flow streams in a microchannel. Nanoparticles are flowing in the core flow stream by the hydrodynamic effect. A single-mode optical fiber is injected vertically. When the particles flow in the microchannel, they will be controlled by three forces: the optical gradient force that pushes particles to the higher intensity, the radiation force that exists in the direction of light propagation, and the drag force that hinders the velocity change of the particles. In principle, larger particles are more easily to be moved by optical forces while smaller particles are easily blocked by the drag force due to its smaller specific surface area. As a result, particles with different sizes can be sorted by a suitable flow rate and input power in the microchannel.

　　Figure 2 shows that optical forces are very sensitive to the refractive indices and extinction coefficient of particles. Fig. 3 shows the simulation results of the nanoparticles under optical field in the central of the input power. Fig. 4 shows the images of the sorting traces of different size particles in the microchannel under the optofluidic forces with different diameters.

　　In conclusion, an optofluidic device for single cell and molecule sorting by using optical force combined with the hydrodynamic focusing is demonstrated.