A novel SERS tattoo for detection of toxic food additives
| Autor: | Chia-Min Wang, 王嘉敏 |
|---|---|
| Rok vydání: | 2015 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 103 We demonstrate a novel and ‘green’ plasmonic technique through the use of gold coated Tattoo paper for biosensing using surface enhanced Raman spectroscopy (SERS). The process is ‘green’ since no toxic chemicals were used, and no polluting waste was produced while synthesizing the special SERS substrate. It is novel, since this is the first demonstration of the use of such a facile technique which can ‘transfer’ a ‘plasmonic’ thin film of gold islands from the Tattoo paper onto any surface for direct sensing of toxins that may be present therein. Through this process, we remove the burden of technical complexity and cost involved in the preparation of commercial SERS substrates. SERS is evolving to challenge and contend with existing conventional technologies used for biomolecules sensing such as fluorescence and mass spectroscopy. SERS maintains the molecular fingerprint of Raman spectroscopy (RS) but improves upon the intrinsic low scattering cross-section of the process via the creation of a surface plasmon in the irradiated noble metal nanoparticles (NP) or islands. We reveal how a common tattoo paper, with a water soluble sacrificial layer, can be coated with a suitable gold pattern which can subsequently be transferred easily onto any substrate or fruit/vegetable surfaces. Surface plasmons generated in these irradiated Au nanoislands increases the Raman scattering signals from toxic chemicals / analytes present on those surfaces. We standardize our detection scheme by using the SERS tattoo for sensing of Rhodamine 6G, a standard Raman analyte, followed by the detection of real toxic chemicals that have been used in food and drinks recently. These include Diethylhexyl Phthalate (DEHP), a plasticizer used in drinks and medicines to fake a ‘natural’ apperance, and Thiabendazole (TBZ), a pesticide used for the preservation of fruits and vegetables. Very low concentration levels, ranging from 10 – 0.001 % of DEHP mixed in real sports drink, and mM – nM levels of TBZ, on the surface of orange peels were detected using the SERS Tattoo. The studies reveal reasonable sensitivity and specificity of detection without the use of any complicated functionalization of the gold patterns. The reproducibility of the SERS Tattoo was quantified by collecting spectra at different points on the same substrate and calculating the relative standard deviation (RSD). The RSD for the SERS Tattoo is 5 – 20 % and is reasonable for a standard sensor. We believe further development of this SERS Tattoo could lead to potential commercialization in the field of food safety applications. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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