Carbon Dot–MnO₂ Nanosphere Composite Sensors for Selective Detection of Glutathione

Abstract

Herein, a fluorescent nanosensor based on carbon dots (Cdots) and different-size MnO2 nanospheres has been synthesized for rapid detection of glutathione (GSH). Water-soluble and highly fluorescent Cdots were prepared by the microwave method using ascorbic acid as the precursor. MnO2 nanospheres of different sizes (large, medium, and small) were prepared by varying the concentration ratio of methionine and KMnO4 at room temperature, which was confirmed by HRTEM analysis. The different sizes of MnO2 nanospheres in Cdots result in quenching of the fluorescence intensity, quantum yields, and average lifetime values, which suggest that the fluorescence resonance energy transfer mechanism occurs between the Cdots and MnO2 nanospheres. The variations of all the photophysical parameters and fluorescence turn off properties of Cdots are significantly tuned depending on the size of the nanospheres. Moreover, detection of GSH in the presence of different-size Cdots@MnO2 systems has been explored. GSH causes the redox reaction in the presence of MnO2, which leads to transformation from MnO2 to Mn2+. As a result, fluorescence restoration (turn on) of Cdots was observed. The large MnO2 nanospheres showed the lowest detection limit of 15 μM for GSH. The synthesized sensing system was very fast, simple, economical, and environmentally-friendly for the detection of the GSH level.

Label-free detection of creatinine using nitrogen-passivated fluorescent carbon dots

“…The experimental results indicated that the emission wavelength lies in the range from 425 to 450 nm, whereas in several reports oxygen-rich CDs have emission at 420 nm. 42 The results indicated that nitrogen passivation leads to a bathochromic shi in the emission spectra of NCDs. The descending order of the bathochromic shi for NCDs is as follows: U-NCDs > C-NCDs > G-NCDs > T-NCDs (Fig.…”

Recent advances in heteroatom-doped graphene quantum dots for sensing applications

“…110 Besides these metal ions, small organic molecules, proteins, and macromolecules also play very important roles in the biological, medical, and environmental systems. [111][112][113] There are various insecticides or pesticides etc. which affect the environment and their detection is needed.…”

Morphology-Dependent Performance of MnO2Nanostructure–Carbon Dot-Based Biosensors for the Detection of Glutathione

“…Recently, we have developed a fluorescent nanoprobe that consists of Cdots and different-size MnO 2 NSPs for ultrasensitive detection of GSH. 29 We studied the different photophysical parameters such as quantum yield, average lifetime values, radiative rate constant, nonradiative rate constant, rate of electron transfer, the efficiency of electron transfer, FRET efficiency, and Forster distance. We also determined the photoluminescence (PL) properties of Cdots and found that the variation in size affects the performance of MnO 2 in the sensing ability of GSH.…”