Electrochemiluminescence (ECL) is a light emission process triggered by electrochemical reactions, in which active species form excited state for light emission through a high-energy electron transfer reaction. Because of the advantages of low background, high controllability, wide linear range and so on, ECL has been widely used in the detection of clinical physiological markers. However, the instruments used in traditional ECL analysis methods can only analyze the overall light intensity of all materials on the electrode surface in the full spectrum band. So this kind of instrument can only allow the establishment of macro-analysis method based on ECL light intensity. ECL microscopy (ECLM) technology with high spatiotemporal resolution is able to provide deeper insights of ECL behavior at the micro-scale, which is developed by Dr Cheng Ma from Yangzhou University and Professor Junjie Zhu from Nanjing University. ECLM is a microscopic imaging technique does not need an excitation light source, which retains the low light background inherited from ECL itself leading to high throughput and spatial resolution. ECLM provides optical signals caused by electrochemical reactions, which cannot be achieved by state-of-the-art optical microscopy. Therefore, ECLM can directly reveals the local electrochemical features like the rate of electrochemical reaction. By using the self-designed ECLM platform, the multi-mode imaging methods including electrostatic adsorption control, photothermal control and ultrasonic control have been developed to obtain kinetics information of protein corona formation at single nanomedicine carriers (Angew. Chem. Int. Ed. DOI: https://doi.org/10.1002/anie.202308950), record the image of the suspension cells CEM (Chem. Sci. DOI: 10.1039/d3sc02298f), and develop in situ modulation of the thickness and intensity of ECL (Anal. Chem. 2023, 95, 9687−9696) were established.
In the research of protein crowns at single nanoparticle, Dr. Cheng Ma from Yangzhou University, Professor Junjie Zhu and Professor Liping Jiang from Nanjing University jointly developed ECLM imaging technology for single particle analysis based on the regulation of adsorption. On the basic of the platform built by the previous national major scientific research instrument project and previous developed works including single particle collisions (Chem. Sci., 2018, 9, 6167), single particle blinking (Nano Lett. 2020, 20, 5008), and single cell imaging (Angew. Chem. 2021, 60, 4907，Chem. Sci., 2022, 13, 13938), by utilizing the competitive adsorption between luminophores and protein molecules at the surface of single particle, real-time monitoring of the protein crown formation process on the particle surface can be achieved. According to this mechanism, the information of protein crown kinetics at the single particle scale can be further obtained.
The results show that the formation of protein crowns on the surface of particles can significantly regulate the ability of particles to enhance the local ECL intensity, and eliminate the interference caused by other components. Finally, using the combination between this phenomenon and ECLM, the formation kinetics of protein crowns can be reported in situ at a single particle level. In addition, the proposal technology is universal. It’s also applicable to other different categories of particles and the study of protein crown formation kinetics in the complex system.
Dr. Cheng Ma from Yangzhou University, Professor Junjie Zhu from Nanjing University and Professor Changjie Mao from Anhui University collaborated on the study of cell membrane proteins by photothermal enhanced ECLM, and established a spatially selective local heat boosting ECLM (HT-ECLM). The HT-ECL showed a higher ECL intensity (up to 63 times) through assembling the laser heating bead module in ECLM at micrometer level, along with an advance of 0.2 V in applied voltage for Ru(bpy)32+/TPA system. The concentrated ECL boosts the contrast of the imagination of CEM by 20.54 times to image the suspension cells CEM. Experimental results and finite element simulation explain the phenomenon of local enhanced ECL because of accelerated reaction rate, enhanced the diffusion coefficient and thermal convection via a photothermal effect. The effect sequence is convection > diffusion > electron transfer process. The work is published in the Royal Society of Chemistry's journal “Chemical Science” under the title “Site-Selective Heat Boosting Electrochemiluminescence for Single Cell Imaging”.
In addition, Cheng Ma's group has proposed the in situ strategy for the adjustment of ECL intensity and the thickness of ECL layer (TEL) flexibly by introducing ultrasonic probes into ECL detectors and microscopes. By observing the effect under ultrasound (US) irradiation in different ECL mechanism, it was found that the effect of US on ECL demonstrated specificity: for the catalytic ECL route, the in situ US boosted the ECL signal from 1.2 times to 4.7 times due to the mechanical oscillation caused by US increased mass transfer during the electrochemical reaction process, the effect of cavitation on the electro-active surface area, and effect of in situ cleaning. However, an opposite trend was observed under the oxidative-reduction route: ultrasound radiation leads to the decrease of ECL intensity. The changes of TEL under US in two ECL routes were observed by homemade imaging setup of ECLM. The finite element simulations were conducted to prove the ECL layer and intensity responses of US in two mechanisms, which is consist with experimental results. Except for the ECL intensity and TEL, the stability of ECL was promoted for electrodeposited Au NPs on indium tin oxide (ITO) electrode in the presence of US due to the weakened surface poison. The proposed strategy is published in “Analytical Chemistry” under the title “In Situ Ultrasound Irradiation for Regulating the Electrochemiluminescence Intensity and Layer”. (Anal. Chem. 2023, 95, 9687−9696). The first author is Zhichen Zhang, a 2021 master's student at Yangzhou University.
Paper information:
An In Situ Investigation of the Protein Corona Formation Kinetics of Single Nanomedicine Carriers by Self-Regulated Electrochemiluminescence Microscopy
Zejing Xing, Xiaodan Gou, Li-Ping Jiang*, Jun-Jie Zhu* and Cheng Ma*
Angewandte Chemie International Edition, 2023, DOI: 10.1002/anie.202308950
Paper links: https://onlinelibrary.wiley.com/doi/10.1002/anie.202308950
Site-Selective Heat Boosting Electrochemiluminescence for Single Cell Imaging
Xiaodan Gou, Yiwen Zhang, Zejing Xing, Cheng Ma*, Changjie Mao*, Jun-Jie Zhu*
Chem. Sci., 2023. DOI:10.1039/D3SC02298F
Paper links: https://pubs.rsc.org/en/content/articlelanding/2023/sc/d3sc02298f
In Situ Ultrasound Irradiation for Regulating the Electrochemiluminescence Intensity and Layer
Zhichen Zhang, Yujing Zhu, Zejing Xing, Jing Li, Qin Xu, Jun-Jie Zhu, Cheng Ma*
Anal. Chem. 2023, 95, 9687−9696
Paper links: https://pubs.acs.org/doi/10.1021/acs.analchem.3c01718
