1、REVIEWColorful“Stars”in the DarkChao Jinga,Yi-Tao Longb,c,*aShanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai,201800,PR ChinabState Key Laboratory of Analytical Chemistry for Life Science;School of Chemistry and Chemical Engineering,Nanjing University,Nanjing,210023,PR China
2、cMolecular Sensing and Imaging Center,Nanjing University,Nanjing,210023,PR ChinaAbstractPlasmonic nanoparticles such as Au and Ag with localized surface plasmon resonance(LSPR)property exhibitunique scattering and absorption features.The plasmonic scattering and absorption bands are mainly located a
3、tvisible light region which can be easily applied in visual detections.By modulating the size,shape and composition ofgold and silver colloid solutions,plenty of colorimetric methods have been designed for the detection of metal ions,biomolecules and environmental contaminants.For many years,the LSP
4、R-based measurements are implemented inreagent tubes.Since 2000,the plasmon resonance scattering(PRS)light of metal nanoparticles captured by dark-fieldmicroscopy enables the investigation at the nanoscale dimension.Mono-dispersed nanoparticles under a dark-fieldmicroscope showed distinct scattering
5、 light spots,like colorful stars in the dark sky.The PRS light of a singlenanoparticle opens a new way for ultra-sensitive sensing which eliminates the average effects in bulk and providesmore accurate reaction information.Thus,individual nanoparticles with specific scattering colors are excellentna
6、noprobes in the applications of biology,physics,and chemistry.In this review,the plasmonics based colorimetricnanosensors are presented.Particularly,the application of in-situ PRS in the dynamically monitoring of electrocatalyticreactions is highlighted.We firstly introduce a short history of the di
7、scovery and development of plasmonic nano-particles from the ancient artwork to the modern characterization techniques.Some factors including morphology,and dielectric constants that are correlated to the LSPR bands and scattering light colors are listed.Secondly,wedemonstrate the use of single plas
8、monic nanoparticles as visualized color-coded nanoprobes.As the morphology ofparticles has strong effect on the PRS light,elegant sensors have been conceived by the etching and growth ofnanoparticles with different sizes and shapes.On the other hand,the real-time monitoring of particle structureevol
9、ution could also reveal the mechanism of the material fabrication at the nanoscale.In addition,core-satellitenanostructures with various linkers are proposed as ultra-sensitive sensors according to the inter-particle couplingeffect.Subsequently,we summarize several advanced techniques for nanoscale
10、signal extraction and amplifications.For instance,to expand the application of colorimetric nanosensors,converting the colors into RGB values couldclearly distinguish the subtle color changes.Combining with high-throughput signal processing method,thousands ofnanoparticles can be rapidly analyzed,wh
11、ich can greatly enhance the measurement efficiency.Except the PRS color,the PRS intensity could also provide abundant information and is easier to be captured.A facile method by convertingthe PRS intensity of single nanoparticles into visible colors is presented,which is mighty suitable for the in-s
12、itumonitoring of fast electrochemical process with high time resolution.Keywords:Plasmon resonance scattering;Dark-field microscopy;Color-coded sensor;Nanoscale electrochemistry;Single-nanoparticle detection1.IntroductionWhen you watch the sky at night,have youthought about what if the stars have co
13、lors?Itwould be such a fantastic scene,but everyoneknows that it is impossible.However,if we movethe view from the extensive universal to the microworld,everything will become possible.Coinagemetal nanoparticles such as Au,Ag,and Cu haveunique LSPR feature which will generate strongReceived 14 Decem
14、ber 2022;Received in revised form 9 February 2023;Accepted 20 February 2023Available online 27 February 2023*Corresponding author,Yi-Tao Long,Tel:(86)13761159439,E-mail address:.https:/doi.org/10.13208/j.electrochem.22180061006-3471/2023 Xiamen University and Chinese Chemical Society.This is an open
15、 access article under the CC BY-NC license(http:/creativecommons.org/licenses/by-nc/4.0/).scattering light under incident light excitation1e3.Employing dark-field microscopy(DFM),the plasmon resonance scattering(PRS)spots ofmono-dispersedplasmonicnanoparticleswithspecific colors will be captured,jus
16、t like thecolorful stars shining in the dark background 4,5.DFM achieves the observation of a single particleat nanoscale dimension which overcomes the op-tical diffraction limitations.Taking advantages ofthe PRS spectroscopy of nanoparticles includinghigh spatial resolution,high intensity,non-blink-ing and bleaching,plentiful label-free and non-invasivesensorshavebeendeveloped6e9.Notably,combining DFM with electrochemistry,the nanoscale electrochemical reactions could bein-situ characterized 10
