Assemblies Of Inorganic Nanomaterials And Their Applications In Biochemical Analysis

The assemblies of inorganic nanomaterials are very important in the nanodevices, and they can be applied in the biosensing and clinic research and the analytical applications of these assemblies are rarely reported. Therefore, finding simple and effective ways to assemble nanomaterials into the superstructures and applying these assemblies in biochemical analysis are very important not only in theory but also in practice. The main contains of this research include two sections.Section one mainly introduces the assemblies of matel nanomaterials and their analytical applications. The main contains are listed as follows:1. We constructed the assembly structure of gold nanospheres and pepetide and applied it for the fluorecent detection of thrombin. Thrombin can selectively cleave the peptide with special sequence, which was assembled with gold nanospheres, and lead to the enhanced fluorescence intensity emitted by tryptophan of the fragment that cleaved from the peptide. This method is simple, and without labeling the peptide with fluorophore to report the signal or other functional groups, such as NH2, SH, and so on. Since there are a lot of enzymes that can hydrolyze peptide with special sequence, it will be possible to develop the designation of this method to detect a variety of target enzymes.2. We demonstrated a novel approach to fabricate the 1-D structure of gold nanorods (AuNRs) based on the specific recognition between protein and its binding aptamer, where thrombin was selected as a model protein. Au NRs, whose ends were modified with the binding aptamer of thrombin, could be assembled to the end-to-end style in the prescence of thrombin, which has been confirmed by the scanning electronic microscopic (SEM) imaging and UV-vis absorption spectra. The assembly efficiency of 1-D AuNRs was affected by the concentration of thrombin and the assembly procedure, that is, a long end-to-end assembly of AuNRs could be obtained when increasing the concentration of thrombin gradually. To the best of our knowledge, this is the first end-to-end assembly of AuNRs based on the aptamer-protein recognition. The linear structure of AuNRs is potentially useful for biosensing, bioimaging and phototherapy. The assembly mechanism can be utilized for the detection of thrombin. Moreover, our method provides evidence that the special recognition between aptamer and protein can organize AuNRs in a predictable fashion, which may be exploited for fabricating other bionanomaterials.3. We developed a new simple and cost-effective method to assemble gold nanocrystals into 1-D chain-like structures using the light reduced silver as linker and successfully applied these assemblies to the SERS and cell imaging. Our method is general and extendable, which can be utilized for construction of 1-D assembly structures of different nanocrystal types. We believe that such nanocrystals assemblies can be used as highly sensitive dark-field light scattering probes and have great promise for the ultrasensitive detection by surface-enhanced Raman scattering (SERS) and for fabrication of nanoscale optoelectronic devices. The assembly machanism can also be applied for the detection of Ag+.Section two mainly introduces the assemblies of carbon nanomaterials and the functional DNAs and their analytical applications. The main contains are listed as follows:1. The assembly of carbon nantube and molecular aptamer beacon (MAB) has been applied for the ATP detection. The MAB can assemble with multi-walled carbon nanotubes (MWCNTs) through theπ-πstacking interaction. Thus, the fluorescence of MAB is completely quenched by MWCNTs. After the addition of ATP, the conformational of the MAB change from hairpin structure to duplex structure, which can't assemble with MWCNTs and the fluorescence of MAB is recovered. Thus, ATP can be detected based on the enhanced fluorescence. Moreover, it has also been successfully utilized in the cellular ATP detection and imaging. Compared with the conventional MAB, our method is simple and cost-effective. The cell penetrability has been improved with the proposed MAB when applied in living cells. Most importantly, the background signal is significantly reduced and the signal-to-background ratio is enhanced greatly owing to the high energy transfer efficiency between MWCNTs and the fluorescent label. 2. The assembly of graphene oxide (GO) and DNAzyme has been applied for Cu2+ detection. The complex of DNAzyme (Cu-Enz) and the substrate DNA (Cu-Sub) can assemble with GO through theπ-πstacking interaction, leading to the fluorescence quenching of the dye modified on the Cu-Sub. After the addition of Cu2+, Cu-Enz can cleave Cu-Sub, making the dye labeled cleaved products can't assemble with GO, and thus the fluorescence is restored. Therefore, Cu2+ can be detected based on the enhanced fluorescence, and a series of experiments have confirmed the reliability of this method. Because the energy transfer efficiency between GO and dye is very high, the background signal has been reduced significantly. This method is simple, selective and cost-effective because only one end of the Cu-Sub needs to be labeled. We believe our method can be used in the other targets detection after the proper design.In summary, we have constructed some simple and universal assembly methods of inorganic nanomaterials, which have been successfully applied in SERS, cell imaging and sensitive detection of targets.