The Development And Application Of Nano Colorimetric Biosensor

Because of the unique physical and chemical properties,Precious metal nanometer materials have been widely used in various fields.Local surface plasmon resonance(LSPR)is a remarkable optical properties of precious metals,it will hapeened when the metal surface under the light irradiation,and the frequency of the incident light is consistent with surface free electronic vibration frequency.These factors mainly influence LSPR,such as the shape and size of the nanoparticles and the refractive index of the surrounding environment medium.Because of the special nature,the biological sensing applications of precious metal nanomaterials have attract a lot of researchers in recent years.Based on these,the paper explores their colorimetric biological sensing applications.Four chapters are referred,the content is as follows:In chapter 1,this chapter is the introduction part,mainly includes the following content:1)the overview of precious metals nano materials;2)the introduction of LSPR biosensor;3)the overview of colorimetric sensors based on gold nanomaterials;4)the research content and significance of this paper.In chapter 2,we mainly introduct the colorimetric biosensor based on alkaline phosphatase induced the growth of gold nanorods.Alkaline phosphatase can catalyze the conversion of ascorbic acid-phosphate into ascorbic acid with high efficiency,and usually used as a marker enzyme of ELISA.Ascorbic acid is a mild reducing agent,which is an important regulator in the growth of gold nanorods.Therefore,we developed a multicolor ELISA method for the sensitive detection of prostate specific antigen disease marker with the naked eye based on the above.The results show that different colors are presented in response to different concentrations of PSA,and a detection limit of 3×10-15g/mL in human serum was achieved.In chapter 3,we developed a kind of LSPR biosensor based on the triangular AgNPRs etching used for the detection of H7N9 virus.The sensor was combined with ELISA,in particular,catalase was marked on the second antibody.The catalase can react with hydrogen peroxide,when we added the same amount of hydrogen peroxide,the rest amount of hydrogen peroxide is different.Hydrogen peroxide acts as an oxidant to etch the triangular AgNPRs into smaller spherical silver nanoparticles,which is accompanied by a substantial blueshift of the LSPR peak and a colourimetric blue-to-purple change that can be observed by the naked eye.The LSPR peak shift enables the quantitative assessment of H7N9 virus due to the remarkable colour change.The limit of detection(LOD)of triangular AgNPRs-based plasmonic ELISA approach can achived tolfg/mL,which exceeds that of the conventional HRP-based ELISA a lot.In chapter 4,we propose a strategy for quantitatively visual detection of p-aminophenol based on iodine-mediated etching of gold nanorods(AuNRs).P-aminophenol is a kind of reducing agent,which can transform KIO3 into I2 effectively.The AuNRs would be etched by the produced I2 in the presence of I-and cetyltrimethylammonium ions(CTA+),accompanied by a blue-shift of LSPR and colorful solutions.The biosensor can achieve a naked-eye detectable limit of 5?M under the optimal conditions.When compared with other detection methods,the sensor has some advantages,such as simple and save time,without complicated instrument and expensive cost,most important of all,it can realize quantitatively visual detection with the naked eye.