| The development of nanomaterials is changing with each passing day.Gold nanorods?GNRs?stand out for their unique local surface plasmon resonance?LSPR?proterties.Thanks to their structural anisotropy,continuous tunability of resonant wavelengths,high stability and low biotoxicity.GNRs have attracted extensive attention in the biochemical sensing field.Different kinds of optical devices and sensors based on GNRs have an important application and development in chemistry,biomedicine and optics.It is well known that the LSPR property of GNRs is sensitive to GNRs size and surrounding media environment.The paper carried out study on the size control and chemical sensing performance of GNRs.The three main research contents of this paper are as follows:?1?modulation of GNRs aspect ratio based on H2O2 oxidation of GNRs.?2?modulation of GNRs aspect ratio based on the mixture of H2O2 and Fe2+?Fenton reagent?oxidation of GNRs and the detection of Fe2+.?3?modification of GNRs with special aspect ratio and the detection of ammonia.?1?Modulation of GNRs aspect ratio based on H2O2 oxidation.Based on the sensitivity of GNRs LSPR to particle size,the aspect ratio of gold nanorod was precisely regulated.The wavelength of longitudinal plasmon absorption band?LPAB?of GNRs monotonically blue shifted along with the prolongation of hydrogen peroxide oxidation time.A linear relationship between LPAB wavelength and hydrogen peroxide oxidation time was revealed.On the other hand,GNRs LPAB wavelength blue shifted linearly with their aspect ratio.From these two relationships,the linear formula between GNRs aspect ratio and H2O2 oxidation time was deduced.Based on this formula,GNRs aspect ratio could be precisely tailored by changing oxidation time.GNRs aspect ratio deduced from the theoretical formula was verified by TEM test of the actual partical size.The average error is 2.92%and the minimum error is 1.09%.The effects of the acidity and temperature of reaction solution on the modulation process of GNRs aspect ratio were also studied.The oxidation process was accelerated by increase in the solution acidity?pH:2.6 to 1.2?or reaction temperature?30?to 60??.?2?Modulation of GNRs aspect ratio based on Fenton reagent oxidation of GNRs and the detection of Fe2+.Due to the strong oxidative properties of Fenton reagent on GNRs,GNRs aspect ratio could also be modulated by Fenton reagent.Based on the effect of Fe2+concentration on the oxidative capicity of Fenton reagent on GNRs,the quantitative detection of Fe2+was realized.The results showed that oxidation capacity of Fenton reagent enhanced with the increase of Fe2+concentration.A linear relationship was revealed between the LPAB wavelength of GNRs and Fe2+concentration in Fenton reagent,based on which the quantitative detection of Fe2+could be realized.Experimental results showed the detection limit was 10-8 M.This method shows favorable Fe2+detection selectivity relative to other metal ions including Na+,K+,Li+,Hg2+,Mg2+,Ni+,Sn2+,Co2+,Cd2+,Cr3+,Zn2+,Ba2+,Cu2+and Fe3+.The GNRs sols under different oxidation time possess of different color,based on which colorimetric detection of Fe2+was realized.?3?GNRs with aspect ratio of 2.21 were selected for ammonium hydroxide detection.The surface stabilizer on GNRs?hexadecyl trimethyl ammonium bromide,CTAB?was replaced by phosphatidylcholine?PC?dissolved in chloroform.After PC modification,the surface zeta potential of GNRs was reduced by 16.8 mV and blue shift of 9.2 nm occoured in LPAB wavelengths of GNRs in the UV-Vis absorption spectra.The characteristic peaks of PC appeared in the fourier transform infrared spectrum of PC-modified GNRs.Then PC-modified GNRs was used for ammonium hydroxide detection.There was a linear formula for LPAB intensity of PC-modified GNRs and ammonia concentration.The response sensitivity is 11.46 a.u.per 1%ammonia content?g/ml?.The minimum detection limitation is 0.004%,much lower than that of the capacitive sensors widely used in industrial application at present?0.1%?.The response time is 180±30 s for ammonium hydroxide concentration below 0.065%.The highlight of this article lies in the explore of precise modulation of GNRs aspect ratio based on the oxidation of GNRs by oxidizing agent and the LPAB wavelength sensitivity to GNRs aspect ratio.In addition,based on the influence of Fenton reagent on the GNRs LSPR,the quantitative and colorimetric detection of Fe2+were realized.Based on the sensitivity of PC-modified GNRs with special aspect ratio to ammonia,quantitative detection of ammonium hydroxide were realized.The experimental results have certain reference value for the practical use of GNRs-based biochemical sensors. |
PDF Full Text Request