Zhiwen Gan,Tian Zhang,Yongmei Hu,Shujun Zhen,Xiaoli Hu
Developing the ratiometric fluorescence probes for biothiols is significant. However, numerous ratiometric fluorescence probes were established based on a hybrid system or complex material. Herein, a simple ratiometric sensor for biothiols was developed by coupling fluorescence (FL) and second-order scattering (SOS) signals based on CdTe quantum dots (CdTe QDs). Under incident light, CdTe QDs with numerous surface traps possessed weak fluorescence but strong SOS due to the occurrence of resonance-enhanced Rayleigh scattering (RRS). With addition of biothiols, FL was enhanced, while SOS was quenched. Mechanistic studies indicated that fluorescence enhancement could result from surface passivation and a static quenching process of RRS could be responsible for the quench of SOS. The probe was employed for the quantification of glutathione (a typical biothiol) with a wide linear range (0.2–80.0 μmol L −1 ) and a low detection limit (0.05 μmol L −1 ). The sensor for biothiols exhibited outstanding merits, including fast response (1 min), simplicity, strong specificity and high sensitivity. Furthermore, the sensor showed a good performance in detecting the total biothiols in real samples. Overall, a new strategy was proposed for designing the simple ratiometric sensor based on quantum dots.
In this work, a facile and label-free ratiometric sensor is constructed for selective determination of norepinephrine (NE) by coupling second-order scattering (SOS) and fluorescence, two different and independent optical signals. Herein, polyethyleneimine (PEI) dilute solution medium shows an intensive SOS signal without any fluorescence response. Interestingly, NE can be selectively induced by PEI to emit bright fluorescence, and meanwhile causes an observable decrease in the SOS signal due to the interactions between NE and PEI. The simultaneous variation of the two independent signals can be used for ratiometric sensing of NE. Under the optimal conditions, the resultant ratiometric sensor displays high sensitivity and selectivity toward NE by simultaneously monitoring fluorescence and SOS signals with the same excitation wavelength. The proposed sensor exhibits a good linear relationship versus NE concentration in the range of 10.0 nM–45.0 μM with a detection limit of 2.0 nM ( S / N = 3) and has been successfully applied to the determination of NE in real samples without the use of any extra reagent. The combination of fluorescence and SOS signals provides a new scheme for ratiometric sensor design, greatly simplifying experimental procedure and effectively enhancing detection accuracy. Moreover, the proposed analytical strategy further broadens the application of dilute solutions of polymers in research into optical sensor and green analytical chemistry.
Graphical abstract
危险品化学品经营许可证（带存储）