The Assembly And Colorimetric Sensing Of Functional Gold Nanoparticles

Gold nanoparticles?AuNPs?have attracted increasing interest as an excellent colorimetric sensing platform due to their unique optical properties.AuNPs,for example,exhibit a strong localized surface plasmon resonance?LSPR?which gives their solution a red colour with a maximum absorption peak at 520 nm?13 nm AuNPs?,whereas it will turn blue with a new absorption band at around 600–700 nm when the particles are aggregated due to a special form of stimulation that makes gold nanoparticles very sensitive to stimulation with a subsequent fast and visible colorimetric readout.In this work,an N-T/gold nanoparticle system was assembled for the convenient and colorimetric identification of Cr based on its coordination chemistry with the thymine derivative?N-T?.In addition to the visible colorimetric changes for the qualitative Cr identification,the A_{630 nm/520 nm} values changed linearly with Cr concentration over a range of 0.5–2.5?M and the detection limits reached 0.03?M and 0.07?M for Cr³⁺and Cr₂O7^2-,respectively,both of which satisfified the Cr water quality standards of the U.S.EPA,WHO and China.Furthermore,a more convenient method was developed for quantitative determination of Cr concentrations in practical samples based on the Eyedropper function in Microsoft's PowerPoin software,wherein the RGB?red,green and blue?value of the sample could be easily screened in the colorimetric card for a more accurate result with good recovery,avoiding complicated instrumentation.Adenosine,as an endogenous molecule in organisms,not only plays an essential role in biological processes,but as well acts as vital intermediate for the synthesis of adenosine triphosphate and so forth.Moreover,extracellular concentration of adenosine in hypoxic tumor microenvironment is reported higher than that of normal tissues.Developing new method,therefore,is of great need for fast and convenient detection of adenosine.Here we demonstrate a colorimetric sensor for adenosine detection based on gold nanoparticle?AuNPs?together with synergistic coordination.It recognizes adenosine selectively and sensitively.Both qualitative and quantitative detection of adenosine is realized by analyzing colorimetric changes through naked-eyes and eyedropper,respectively.This sensor can provide rapid assay of adenosine in patients'serum sample in remote areas and underdeveloped areas.