High-throughput detection of mycophenolic acid in human plasma based on sensitive and rapid fluorescence nitrogen-doped carbon dots sensing platform.

In this experiment, a water-soluble, nitrogen-doped yellow-green fluorescent N-doped carbon dots (N-CDs) were synthesized by one-step hydrothermal method using ß-cyclodextrin as carbon source and L-phenylalanine as nitrogen source. The fluorescence quantum yield of the obtained N-CDs was as high as 9.96%, and the N-CDs exhibited photostability at different pH, ionic strength and temperature. The morphology of the N-CDs was approximately spherical with an average particle size of about 9.4 nm. Based on the fluorescence enhancement effect of mycophenolic acid (MPA) on N-CDs, a quantitative detection method of MPA was established. This method had good selectivity and high sensitivity for MPA. The fluorescence sensing system was applied to the detection of MPA in human plasma. The linear range of MPA were 0.06-3 µg·mL-1 and 3-27 µg·mL-1 with a detection limit of 0.016 µg·mL-1, and the recoveries were 97.03∼100.64 % with the RSDs of 0.13∼2.90 %. The interference experiment results showed that the interference of other coexisting substances, including Fe3+, can be ignored in the actual detection. Comparing the results measured by the established method with the EMIT method, it was found that the results obtained by the two methods were similar, and the relative error was within ± 5 %. This study provided a simple, rapid, sensitive, selective and effective method for the quantitative analysis of MPA, and was expected to be applied to clinical MPA blood concentration monitoring.

Rapid and sensitive fluorescence determination of oxytocin using nitrogen-doped carbon dots as fluorophores.

In this work, a novel nitrogen (N)-doped carbon dots (N-CDs) was prepared with quercetin as the carbon source and o-phenylenediamine as the nitrogen source by hydrothermal synthesis, and their application as fluorophores for selective and sensitive determination of oxytocin were reported. The fluorescence quantum yield of the as-prepared N-CDs, which exhibited good water solubility and photostability, was about 6.45 % using rhodamine 6 G as reference substance, and the maximum excitation (Ex) and emission (Em) wavelength were 460 nm and 542 nm, respectively. The results illustrated that the direct fluorescence quenching of N-CDs fluorophore for the detection of oxytocin achieved good linearity in the range of 0.2-5.0 IU/mL and 5.0-10.0 IU/mL, the correlation coefficients were 0.9954 and 0.9909, respectively, and the detection limit was 0.0196 IU/mL (S/N = 3). The recovery rates were 98.8∼103.8 % with RSD= 0.93 %. The interference experiments showed that common metal ions, possible impurities introduced in production and coexisting excipients in the preparation had little adverse influence on selective detection of oxytocin by the developed N-CDs based fluorescent detection method. The mechanism study on the fluorescence quenching of N-CDs by oxytocin concentrations under the given experimental conditions demonstrated that there were internal filtration effect and static quenching in the system. The developed fluorescence analysis platform for the detection of oxytocin had been proved to be rapid, sensitive, specific and accurate, and to be used for the quality inspection of oxytocin.

Targeted therapy for the treatment of gliomas with multifunctional orange emissive carbon dots.

As a nano-material, carbon dots have been extensively studied and applied in many ways. Herein, iron-doped orange emissive carbon dots (ICDs) were easily synthesized using the hydrothermal method and coupled with Trf and glucose oxidase (GOD) simply by virtue of the abundant functional groups on their surface. The resulting carbon dots were named IGTCDs. The obtained IGTCDs possessed targeting, therapeutic and imaging functions, achieving the enzymolysis of glucose, the decomposition of H2O2 and the release of reactive oxygen species (ROS) sequentially in gliomas as a multifunctional nano-catalyst, and achieving an efficient glioma targeted killing effect. On the basis of the ideal biocompatibility of the IGTCDs with a cell survival rate of over 85%, even at a high concentration (500 µg ml-1), the IGTCDs, which were coupled substances present within the organism, glucose oxidase and transferrins, showed an obvious inhibitory effect on the growth of tumor cells, and the survival rate of the C6 cells was only 28.10% at 300 µg ml-1. The highly efficient anti-tumor effect was further demonstrated in the treatment of mice suffering from glioma, and the tumor inhibition rate was increased to 56.21-98.32%. This safe and effective multifunctional tumor inhibitor could be conveniently synthesized in large quantities, verifying the feasibility of the anti-tumor therapy based on the tumor microenvironment (TME), creating a novel method for the application of carbon dots in tumor treatment and providing a novel, reasonable and effective method for the treatment of cancer and gliomas.