Application Of Functional Nano-biomimic Interface System For Life Analysis

With the development of nanotechnology, a variety of nanomaterials has been exploited for the extensive potential applications in the field of photoelectrochemical sensors which provide new development opportunities for nano-bio interface. Nanoparticles are similar to the spatial dimensions of biological molecules in living systems which is more accessible to its targeted sites and could maintain its activity, at present, the controlled and efficient coupling of biological molecules on nano-interface is the hot spots in field of nano-biomimic research. Functional nano-bio interface synergy and signal amplification, making it a biocompatible interface with potential for development. Therefore, constructing a new type of high selectivity and sensitivity of functional nano-biomimic interface has important significance in the life analysis, nano-sensing and a variety of interdisciplinary fields. Based on these, a series of functional nano-biomimic interface has been designed for exploiting the electron and proton transfer of coenzyme Q derivatives in the part of mitochondrial respiratory chain; achieving the selective detection of superoxide radicals in living cells; in situ monitoring the growth and surface oxidization process of single Cu nanoparticles; recognizing quantitatively the specific binding of the antigen-antibody at single nanoparticle level. The details are summarized as follows:1. Coenzyme Q Functionalized CdTe/ZnS Quantum Dots for ROS ImagingThe three synthesized redox-active coenzyme Q disulfide derivatives [CoQCnS]2 with different alkyl chain lengths (n=1,5 and 10) were functionalized on quantum dots (QDs) surface by self-assembly methods. The biomimic interface has been fabricated exploiting coenzyme Q derivatives that can be chemically attached to the surface of the QDs in an effort to mimic the electron and proton transfer in the part of mitochondrial respiratory chain. Results show that [CoQH2CnS]2 enhances the fluorescence intensity significantly, while modification using the equivalent but oxidized version [CoQCnS]2 (0.03 mM) results in a reduction of the fluorescence intensity of the QDs under identical conditions. The enhancement/quenching effect in QDs could be reversibly tuned by spectroelectrochemistry. The fluorescence intensity of [CoQH2C]S]2-QDs system are quenched when increasing the concentration of O2·-, which displays the potential for the quantification of O2·- over a wide linear range. As increasing the concentrations of NADH, the fluorescence intensity of [CoQC1S]2-QDs system enhanced, and this could be used to detect NADH effectively and thus provide the basis of a potential sensor system. Moreover, our probe could be real time detection of ROS concentrations in living cells.2. CdSe/ZnS Quantum Dot-Cytochrome c Bioconjugates for Selective Intracellular O2·-SensingA fluorescence detection probe was constructed by coupling QDs and oxidized Cyt c, which is sensitive and selective for O2·- in living cells. Result shown that the oxidized Cyt c efficiently quenches the fluorescence of the negatively capped QDs, while the fluorescence of the QDs renewed when the reduced form of Cyt c incubated with negatively capped QDs. When O2·- was added to the system of QD-oxidized Cyt c, the oxidized Cyt c could be reduced by the O2·- radicals generated in solution, results in a recovery of the fluorescence intensity of the QDs. Thus, this system could be used as an effective probe selective for O2·- detection over a broad range, without interference from other ROS and relevant intracellular components. Moreover, this probe responds to the changes of O2·- concentrations in living cells with high sensitivity.3. Real-Time Monitoring of the Aging of Single Plasmonic Copper NanoparticlesThe Cu nanoparticles (CuNPs) could be obtained by electrochemical deposition of CuSO4 solution on an ITO template, in situ and real time monitoring the growth process of a single CuNP and recording the surface oxidation process after the CuNP was exposed to air by dark-field microscopy (DFM) and plasmon resonance Rayleigh scattering (PRRS) spectroscopy. Under the air-saturated conditions, the successful PRRS spectraλmax response of single CuNPs exhibited distinct peak-shift behavior towards longer wavelengths from 575 nm to 665 nm and then blue-shifted over the range of 665 to 605 nm, and these changes were indicated by the visible color changes in the DFM images from olivine to red and then to grey-blue, and the peak intensity in the CuNP scattering spectra decreased as the exposure time of the solution to air increased.4. Electrodeposition of Single-Metal Nanoparticles on Stable Protein 1 Membranes: Application of Plasmonic Sensing by Single NanoparticlesThe phospholipids vesicles with stable protein 1 (SP1) was functionalized on silanized ITO template surface, and the biomimic interface has been fabricated monitoring the controllable growth of single Au, Ag and Cu NP and analysing quantitatively the specific binding of SH-poly(dT) and Fab HED10. The present study has implemented DFM and PRRS spectroscopy at single NP level in situ and real time monitoring the growth process of single Au, Ag and CuNP. Results show that the deposited NPs occur only on the SP1 pore. Also, the PRRS spectral shifts enabled the probing of specific binding events of SH-poly(dT) and Fab HED10 at the single NP within the concentration range of 10-8 M～10-5 M.