| In this paper,a series of three-dimensional nano-structure were developed based on gold nanoparticles,silver nanoparticles,upconversion nanoparticles through DNA self-assembly technology and the optical signal enhancement effect of the self-assembly was further studied.Gold nano-pyramid probe and upconversion-silver core-shell structure were developed based on the optical signal enhancement effect,and the enhancement mechanism was also studied.The developed nanostructures were used for sample,fast and tulra-sensitive detection of target.In addition,the plasmon resonance effect of noble metal was used for photothermal application,achieving an excellent synergistic effect in bacteriostasis field.Firstly,gold nanoparticles and silver nanoparticles were synthesized respectively.Gold nano-pyramid structure was established with DNA sequence by two steps.The aptamer of vascular endothelial growth factor（VEGF）was attached on the scafford of the pyramid structure through the principle of complementary base pairing.Transmission electron microscopy,dynamic light scattering and uv-vis spectra were recorded and finite difference time domain was used to simulate the regional electromagnetic field of the nanoprobe,which is in accordance with the experiment.The developed pyramid assembly was used as a probe to achieve ultra-sensitive detection of vascular endothelial growth factor,with a detection limit of 22.6 aM.Secondly,based on the above-mentioned self-assembly technology,gold nano pyramid was fabricated from single gold nanopartiles by the assistance of DNA sequence.According to the（PCR）-based telomeric repeat amplification protocol,a DNA-driven nanoparticle self-assembling pyramid encoding a Raman reporter（Cy5）is developed for telomerase detecting in live cells using SERS and fluorescence signal.Such a dual-mode strategy is the first to realize the detection of intracellular telomerase activity in situ.The developed probe has high intracellular stability,good specificity,high sensitivity,and the limit of detection level is 6.2×10–15 IU。Thirdly,gold nano particles with a diameter of 4 nm and upconversion nanoparticles with a diameter of 20 nm were synthesized respectively based on the above mentioned systhesis method of noble metal.Six sets of DNA sequences with different lengths which paired with each other were used as linker for the attachment of gold nanoparticles and upconversion nanoparticles.Based on the plasmon resonance effect of noble metal nanoparticles and the unique luminescence properties of upconversion nanoparticles,the emission peaks of specific wavelengths of upconversion nanoparticles are enhanced,and the enhanced signal is used to detect vascular endothelial growth factor.With the increasing of VEGF,the assembly is gradually destroyed due to competition,the resonance enhancement effect dependent on the noble metal gradually weakens,resulting in the weakness of fluorescence signal gradually.Lastly,based on the above-mentioned upconversion nanoparticle synthesis technology,the surface of upconversion nanoparticles were coated with silver shell.when the plasmon resonance absorption of noble metal match to the emmission of the upconversion,the luminescence of upconversion would be converted into heat.Such photothermal principle was used for bacteriostasis.The photothermal effect of the core-shell structure combined with the antibacterial properties of the silver shell form a multi-effect and multi-mode antibacterial effect.The successful preparation of this material makes it possible to sterilize with near-infrared light in a more demanding environment,which can provide potential solutions for sterilization in the future food or hygiene field. |
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