The Assembly And Application Of Functional Gold Nanoparticles

Gold nanoparticles（Au NPs）exhibit unique optical properties,for example,the surfaceplasmon resonance（SPR）,whose wavelength can be adjusted by changes of the size and morphology of Au NPs.The molar extinction coefficient of Au NPs is 1000 times larger than traditional dyes.Due to this property,Au NPs based-colorimetric assay shows a visible signal by naked eyes,which makes Au NPs an excellent platform for the sensitive colorimetric recognition of targets.In this work,the Au NPs,synthesized by sodium citrate,were functionalized to fabricated functional molecule/Au NPs system for sensitively and rapidly detecting metal ions(Pb²⁺and Ag+)and creatinine（an important biological molecule）.（1）Creatine could attach on the surface of Au NPs through electrostatic interaction,so creatine/Au NPs system was fabricated.Pb²⁺ could bind creatine due to the coordination interaction,resulting in the aggregation of Au NPs.The process was indicated by a red shift of UV-vis absorption,along with a distinct red-to-blue color change.Besides,there was a good linear relationship（R2=0.982）between the absorbance ratio of A620 nm/520 nm and Pb²⁺concentration（5³0 μM）.（2）Due to electrostatic interaction and coordination chemistry,adenosine and creatinine functionalized Au NPs system was established for Ag+.The introduction of Ag+into the system could result in the aggregation of Au NPs,it’s because that adenosine,creatinine and Ag+ possessed a synergistic coordination interaction on Au NPs surface.Under the optimized experimental conditions,the absorbance ratio（A620 nm/520 nm）was linearly proportional to the Ag+concentration over a range of 0.1⁰.9 μM,（R2is 0.990）,and the LOD reached 0.02 μM.（3）Based on the above synergistic coordination interaction above,while changing the order of functional molecules and metal ion can realize the different target sensing.Consequently,adenosine/Ag+-Au NPs system was presented.The creatinine concentration could be qualitatively recognized by naked-eyes and quantitatively measured by absorbance changes.The absorbance ratio of A630 nm/520 nm established good linear relationships with creatinine concentrations in both serum（0.2² n M,R2=0.990）and urine（50⁴00 μM,R2=0.982）,which could be used for early diagnosis of kidney disease.The functional Au NPs systems above have potential for a rapid and sensitive recognition of detrimental metal ions and biological molecule in practical samples when the test kit was fabricated.