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Breakthroughs in Quantum Dot Aptasensor Research by Nanobiology Team

The nanobiology team led by Professor Han Heyou (College of Science) have made new breakthroughs in quantum dots(QDs) dual-signaling ratiometric biosensor technology and recently published their research results successively in an ACS publication Analytical Chemistry. Graduate student Zou Chenchen and doctoral student Shao Kang are respectively the first authors of the two articles “Carbon-Dot and Quantum-Dot-Coated Dual-Emission Core–Satellite Silica Nanoparticles for Ratiometric Intracellular Cu2+ Imaging” and “Signal-Amplified Near-Infrared Ratiometric Electrochemiluminescence Aptasensor Based on Multiple Quenching and Enhancement Effect of Graphene/Gold Nanorods/G-Quadruplex.” Professor Han is the corresponding author of both.

Dual-signaling ratiometric biosensor technology has attracted particular attention because it can eliminate through self-calibration both the interference of the environmental changes (such as the auto-fluorescence of biological tissues and the oxidation-state and reduction-state of blood serum, etc.) and the abnormal changes in signal correcting. This dual-signal detection mode is more accurate and credible compared with the single-signal detection mode.

In the first article, a new ratiometric fluorescent probe was developed hybridizing two fluorescence nanodots (QDs and carbon dots (CDs)) capped around the silica microsphere. It could be utilized for precise and efficient ratiometric fluorescence imaging of intracellular copper ions based on CDs’ non-fluorescence quenching response and QDs’ selective response to Cu2+. The interference of overlapping peaks to the fluorescence detection can be skillfully avoided due to the stability of dual-emission peaks of the QDs and CDs under the same photoluminescence irradiation of certain wavelength and to enough gap between the two peaks. This peculiarity makes the nanoprobe very suitable for intracellular confocal double-channel imaging. The near-infrared QDs used for imaging do no harm to the tissues or cells because high energy radiation that may cause damage to them under short wavelength excitation can be avoided. Therefore, it is suitable for detecting effectively the copper ion in the living cells as well as in the environment.

In the second article, the researchers fabricate an ultrasensitive near-infrared ratiometric electrochemiluminescence (ECL) aptasensor based on a dual-potential signal amplification strategy triggered by the quencher/enhancer [graphene/hemin/gold nanorods/G-quadruplex–hemin (rGO–H–AuNRs–G4H) composite] taking two thrombin aptamers as sensor mode. They developed a new, accurate and sensitive aptasensor mode that enables the dual-signaling detection to switch from “ON-OFF” to “OFF-ON” mode and multiple signal amplification, thus offering new ideas for the development of ratiometric ECL technology.

(By Li Yutong)