Investigations on the amalgamation of gold nanorods by iodine and the detection of tetracycline

Abstract

The morphological transformation process of gold nanorods (Au-NRs) resulting from the reaction between tetracycline and iodine was monitored by the plasmon resonance absorption (PRA) spectra and the scanning electron microscope (SEM) images. It was found that iodine could fuse Au-NRs into sphericity with the lower aspect ratio and blue shift of the longitudinal PRA band. It was found, however, that the presence of tetracycline, since it can react with I 2 , decreases the effective concentration of I 2 and its fusion effect on Au-NRs. As a result, the longitudinal PRA of Au-NRs shifts to longer wavelength linearly with increasing the concentration of tetracycline. With that, tetracycline can be detected in the range of 5.0×10 −5 -5.0×10 −4 mol·L −1 , with a limit of determination (LOD) of 2.4×10 −6 mol·L −1 (3σ). Most foreign substances in the samples did not interfere in the detection, and tetracycline in the synthetic samples could be detected with the recovery in the range of 92.8%-107.2%, and RSD lower than 4.3%. The concentration of tetracycline in milk detected with standard addition method was so low that it accorded with the safety regulation.gold nanorods, iodine, tetracycline hydrochloride, plasmon resonance absorption Due to the broad range of activity against pathogens and low cost, tetracycline antibiotics are widely used against bacteria infection [1][2][3] or as feed additives for growth promotion in veterinary practice [4,5] . Medically, tetracycline can be employed to treat gallbladder disease [6,7] , malignant pleural effusions [8 -12] or periodontal disease [13] . However, relatively high levels of antibiotic residues may lead bacteria to resist against antimicrobial reagents [14,15] , or can bring about allergic reactions in some hypersensitive individuals [16] . Besides, their degradation products are also toxic to some degree [17] . Furthermore, because of the complexation of tetracycline with Ca 2+ [18] , relatively high level of antibiotic residues enrich in the animal bones when animals are bred with tetracycline in a long period [19] , as well as in fish [4,20] , meat [21][22][23] , eggs [24][25][26][27] and milk [28,29] . Therefore, the detection of tetracycline is closely linked to human life.By now, a variety of methods have been applied to detecting tetracycline, such as microorganism control experiment [30] , immunoreactions [31] , fluorescence method [32] , capillary electrophoresis [20] and high-performance liquid chromatography (HPLC) [33][34][35] . All of them supply the structural information or pharmacologic function of tetracycline, but microorganism control experiment lasts too long without sensitivity, immunoreactions need the complicated and long-term operation, capillary electrophoresis is carried out with poor recurrence and HPLC requires costly instrument and professional operation. All of these limitations confine the applications of these methods. Therefore, it is necessary to develop a rapid and simple method for determination of tetracycline.Our previous study [36...

Iodine-Mediated Etching of Gold Nanorods for Plasmonic ELISA Based on Colorimetric Detection of Alkaline Phosphatase

“…With the increase in I 2 concentration, the longitudinal LSPR shifts to shorter wavelength gradually, which is attributed to the decrease in aspect ratio of AuNRs (SEM images A–C in Figure ). Although the iodine-induced morphological change of AuNRs has been widely reported, the mechanism for this phenomenon has not reached a consensus. − On the basis of our results, we propose a new mechanism of CTA + -assisted oxidation of gold. The reaction is proposed as follows: …”

Iodine-mediated etching of gold nanorods for plasmonic sensing of dissolved oxygen and salt iodine

“…It is worth noting that the proposed etching mechanism is totally different from the iodine-induced transformation of AuNRs mentioned in previous reports. [36][37][38][39][40] So, it is essential to study more about the mechanism and it is also interesting to expand this kind of sensing method.…”

An inorganic-organic hybrid supramolecular complex (H3O)4[(CoC14H12N2O10)1.5(SiW12O40)]·2H2O: synthesis, structure, properties, and application to catalytic elimination methanol

“…As "molecular devices", POMs are a good multi-electron acceptor, which can be used as polydentate ligands. According to the molecular design principles, the metal ions coordinate with ligands to generate organic-inorganic complexes, then combine with polyoxometalates for interesting structures, giving complex structures and properties [2].…”