Fabrication of a Ratiometric Fluorescence Sensor Based on Carbon Dots as Both Luminophores and Nanozymes for the Sensitive Detection of Hydrogen Peroxide

Abstract

The construction of novel fluorescent nanozymes is highly desirable for providing new strategies for nanozyme-based sensing systems. Herein, a novel ratiometric fluorescence sensing platform was constructed based on carbon dots (CDs) as both luminophores and nanozymes, which could realize the sensitive detection of hydrogen peroxide (H2O2). CDs with peroxidase-mimicking activity were prepared with a one-step hydrothermal method using L-histidine as an inexpensive precursor. CDs had bright blue fluorescence. Due to the pseudo-peroxidase activity, CDs catalyzed the oxidation of o-phenylenediamine (OPD) with H2O2 to generate 2,3-diaminophenolazine (DAP). The fluorescence resonance energy transfer (FRET) between CDs and DAP resulted in a decrease in the fluorescence of CDs and an increase in the fluorescence of DAP, leading to a ratiometric fluorescence system. The free radical trapping experiment was used to investigate the reactive oxygen radicals (ROS) in the catalytic process of CD nanozymes. The enzymatic parameters of CD nanozymes, including the Michaelis constant (Km) and the maximum initial reaction velocities (Vmax), were investigated. A good affinity for both OPD and H2O2 substrates was proven. Based on the FRET between CDs and OPD, a ratiometric fluorescence analysis of H2O2 was achieved and results ranged from 1 to 20 μM and 20 to 200 μM with a low limit of detection (LOD, 0.42 μM). The detection of H2O2 in milk was also achieved.

Gadolinium-Doped Carbon Dots with Dual Enzyme Activity for Visual Detection of Cu2+ and Antibacterial Applications

“…Since UV-triggered oxidation is usually linked to reactive oxygen species (ROS), such as hydroxyl radicals (•OH), superoxide negative anions (O 2 •– ), singlet oxygen ( 1 O 2 ), and holes (h + ), intermediary scavenging experiments were used to investigate the mechanism of UV-triggered catalytic oxidation of CDs. , As shown in Figure , in an oxygen removal environment by nitrogen passage, the absorbance of the system obviously decreases, indicating that the dissolved oxygen in the solution plays an important role in catalyzing oxidating OPD. Since UV ascorbic acid (AA) can effectively scavenge O 2 •– , the addition of AA into the CDs-OPD system could greatly lighten the solution color, showing the involvement of O 2 •– in the oxidation of OPD as an effective active material.…”

“…•− ), singlet oxygen ( 1 O 2 ), and holes (h + ), intermediary scavenging experiments were used to investigate the mechanism of UV-triggered catalytic oxidation of CDs. 43,44 As shown in Figure 3, in an oxygen removal environment by nitrogen passage, the absorbance of the system obviously decreases, indicating that the dissolved oxygen in the solution plays an important role in catalyzing oxidating OPD. Since UV ascorbic acid (AA) can effectively scavenge O 2…”

Disposable Electrochemical Sensors for Highly Sensitive Detection of Chlorpromazine in Human Whole Blood Based on the Silica Nanochannel Array Modified Screen-Printed Carbon Electrode

“…Graphene-based materials (e.g., 0D graphene quantum dots [ 41 , 42 ], 2D graphene nanosheets [ 43 ], and 3D porous graphene [ 44 ]) usually exhibit novel optical/electrical/catalytic properties [ 45 , 46 , 47 , 48 ] and have been widely used to construct various sensing systems with improved analytical performance [ 49 , 50 , 51 ]. Figure 1 a illustrates the fabrication process of VMSF/ErGO/SPCE.…”

Equipment of Vertically-Ordered Mesoporous Silica Film on Electrochemically Pretreated Three-Dimensional Graphene Electrodes for Sensitive Detection of Methidazine in Urine

“…Graphene-based nanomaterials contain 0D graphene quantum dots [ 32 , 33 ], 2D graphene nanosheets [ 34 ], 3D porous graphene [ 35 ], and so on. Owing to unique optical, electrical, or catalytic properties, the graphene family commonly displays great potential for the fabrication of a novel sensing platform with good performance [ 36 , 37 , 38 ]. Amongst these, graphene is a two-dimensional (2D) nanocarbon material with honeycomb structure connected by sp 2 carbon atoms that has single-layered thickness, excellent electron transfer rate, and high theoretical specific surface area.…”