Bionic Substrate-based SERS Analysis Of Metal Ions, H₂O₂ And Glucose

-Superhydrophobic phenomenon widely exist in every corner of the nature, for example: lotus leaf, butterfly wings, leech legs, gecko’s foot, and so on. These phenomenon not only represent the characteristics of every creature, it is also the fundamental condition or skills for their survival, such as: lotus leaf surface selfcleaning effect can protect it from imbrued in the silt, the ultra-high hydrophobic performance of leech leg can ensure its freely walk on water, gecko’s foot is the fundamental guarantee of crawling on the walls. As these special performance, scientific research workers gradyully changes their focus from exploring to bionic study. Superhydrophobic bionic materials because of its surface with super hydrophobic surface and special micro/nano structure has been widely applied to various fields, such as: protection against frost, anti-fog, self-cleaning, etc, which benefits from their hydrophobic properties and special micro-nano hierarchical structure. At the same time, superhydrophobic surface was often used in detection field for sample concentration and enrichment, in order to further improve the detection sensitivity. As the amount of the test samples in SERS detection is often very less, the concentration and enrichment effect of the superhydrophobic surface could be used for further improve the sensitivity of SERS analysis. In this paper, we mainly focus on preparation of the three has superhydrophobic materials and explore its application in SERS detection field. The main contents are as follows:1. Preparation of Zn/Ag superhydrophobic materials and its application in SERS analysis.A facile method for fabricating a Zn/Ag superhydrophobic material proposed and the Zn/Ag substrate exhibits preeminent superhydrophobc performance. The concentration and enrichment property of this superhydrophobic surface was utilized in quantitative and qualitative analysis of Cu²⁺ and Ni²⁺. The Cu²⁺ and Ni²⁺ were first coordinated by Zincon and the complex was dropped on the surface of the as prepared substrate. After the evaporation of the solution, the sample was collected to a point and the Raman spectra of the sample was achieved, which could be used for quantitative and qualitative analysis.A dynamic SERS spectra was collected on the superhydrophobic surface, with the evaporation of the droplet on this surface. The result shows that SERS spectra intensity of the sample in the droplet first increased and then decreased. We can thus conclude that a max SERS intensity exit during the evaporation process and this research could be used for increasing the detection sensitivity.2. Application of biomimetic?superhydrophobic substrate for the quantitative analysis of H₂O₂.A Cu/Ag superhydrophobic was first prepared and a serious of Cu/Au hydrophilic array point, which shows the HRP-like property, was integrated on the Cu/Ag superhydrophobic surface. The Cu/Au point shows excellent H₂O₂ responsive property. Based on this array chip, quantitative analysis of H₂O₂ was proposed. OPD molecule was utilized as a chromogenic substrate and Au colloid was used as an enhanced regent. The concentration-depend SERS intensity of the OPD molecule was used for the quantitative analysis of H₂O₂. By using the dualfunctional array chip in SERS analysis, only 2 μL was enough and the detection sensitivity was improved and the absolute detection quantity is 3 pmo L/ 2u L.3. Combination of biomimetic-superhydrophobic substrate and resonance raman method for the quantitative analysis of H₂O₂.Depends on the above detection method, SERS was replaced by resonance raman method. In this part, 5-Asa/Ti O2 complex was used as the chromogenic substrate. The excited electronic state of the catalytically product matched with the laser wavenumber used in the raman detection, 532 nm. Based on the dual-functional H₂O₂ responsive chip, the quantitative analysis of H₂O₂ was proposed. The utilized of resonance Raman simplify the testing process without using Au as a enhance regent. The excellent repellence of the superhydrophobic surface lead to much less sample used in the analysis.4. Bionic-SERS-active substrate for the quantitative analysis of glucoseAfter roughen by HNO3 and then modified with alkyl sulfhydryl, the Cu surface shows perfect superhydrophobic property. A serious of hydrophilic array point was prepared on the Cu surface by a template method. The Ag nanoparticles were deposited on the array point with the assistance of PDDA by self-assemble and it shows high SERS-activity. Glucose oxidase was integrated onto the Ag nanoparticles with 4-MBA as a linker. The as prepared array chip shows glucoseresponsive property. The reaction between glucose oxidase and glucose will affect the the electronic structure of 4-MBA, which leads to the SERS spectra changed regularly with the variation of the glucose concentration. Based on the superhydrophobic SERS active array chip, the quantitative analysis of glucose was proposed. This detection method show great specificity to glucose and high sensitivity. The excellent repellence of the Cu surface help to save sample used in the analysis.