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Published on: September 17, 2017
The visual detection of amoxicillin using a dual-mode probe based on CQD-doped MnO2 nanospheres
Zhenhua Wu1, Nani Fu2, Xianqin Han2
1Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases (Ministry of Education), Gannan Medical University, Ganzhou 341000, P. R. China.
Abstract:
Amoxicillin (AMO), a broad-spectrum penicillin antibiotic, has been widely employed for the treatment of bacterial infections. However, the unreasonable use of amoxicillin may cause a serious threat to human health, and its visual determination remains a challenge. Herein, a MnO2@CQD probe was used for the dual-mode detection of AMO, which was synthesized by doping CQDs into MnO2 nanospheres. In the colorimetric mode, MnO2@CQDs oxidized colorless 3, 3', 5, 5'-tetramethylbenzidine (TMB) into yellow oxidized TMB (oxTMB). In the presence of AMO, AMO could deoxidize oxTMB to cause multiple color changes from yellow to colorless. In the fluorescence mode, MnO2@CQDs initially exhibited quenched fluorescence due to the presence of MnO2. Upon the addition of AMO, MnO2 was reduced to Mn2+ ions, and then CQDs were released and their fluorescence was recovered at an emission wavelength of 450 nm. The colorimetric detection range was wide from 0.005 to 0.09 μM, and the detection limit was 1.6 nM. With increasing concentration of AMO, the color changed from yellow to colourless, which allowed naked eye observation. The fluorescence method was rapid, requiring only 1 min, and exhibited a linear detection range from 0.003 to 0.045 μM, with a detection limit as low as 1 nM. In addition, a paper-based sensing platform was constructed, where fluorescence intensity transitioned from dark to blue with increasing AMO levels. The RGB analysis demonstrated that AMO concentration could be discriminated effectively using a smartphone-assisted detection system. The MnO2@CQD sensor showed excellent selectivity and specificity for AMO colorimetric and fluorescence detection. Moreover, the probe exhibited good practicability in tap water, milk and serum, with results comparable to those obtained by high-performance liquid chromatography. Overall, the MnO2@CQD dual-mode probe provides an efficient, convenient and rapid strategy for the visual and quantitative detection of AMO in complex environments.
Insights
A novel MnO₂@CQD probe enables dual-mode visual and fluorescence detection of amoxicillin (AMO). This rapid, selective sensor offers accurate quantification in various samples, addressing challenges in antibiotic monitoring.
Area of Science:
- Materials Science and Nanotechnology
- Analytical Chemistry
- Biomedical Engineering
Background:
- Amoxicillin (AMO) is a widely used antibiotic, but its misuse poses health risks.
- Accurate and accessible methods for detecting amoxicillin are crucial for public health.
- Visual determination of amoxicillin remains a significant analytical challenge.
Purpose of the Study:
- To develop a dual-mode sensor for the visual and quantitative detection of amoxicillin.
- To synthesize and characterize a novel manganese dioxide@carbon quantum dot (MnO₂@CQD) probe.
- To evaluate the sensor's performance in complex environmental and biological samples.
Main Methods:
- Synthesis of MnO₂@CQD nanospheres via doping carbon quantum dots into MnO₂ nanospheres.
- Colorimetric detection based on AMO-induced de-oxidation of TMB by the probe.
- Fluorescence detection utilizing AMO-induced reduction of MnO₂ and recovery of CQD fluorescence.
- Construction of a paper-based sensing platform with smartphone-assisted RGB analysis.
Main Results:
- The MnO₂@CQD probe demonstrated dual-mode detection capabilities for amoxicillin.
- Colorimetric detection showed a wide linear range (0.005–0.09 μM) with a low limit of detection (1.6 nM) and naked-eye observability.
- Fluorescence detection was rapid (1 min) with a linear range (0.003–0.045 μM) and a very low limit of detection (1 nM).
- The sensor exhibited high selectivity and specificity, with practical applicability in tap water, milk, and serum, comparable to HPLC.
Conclusions:
- The MnO₂@CQD dual-mode probe offers an efficient, convenient, and rapid strategy for amoxicillin detection.
- The developed sensor facilitates both visual and quantitative analysis of amoxicillin in complex matrices.
- This approach provides a promising tool for monitoring antibiotic usage and ensuring public health safety.
