Mercaptopurine (6-MP) is used to treat leukemia and autoimmune diseases. However, higher levels of this drug in body fluids can cause serious health problems. In a recent article published in the journal ACS Biomaterials Science Engineering, the researchers prepared a quantum fluorescence method based on quantum carbon points to detect 6-MP in human body fluids.
Study: Detection of selective fluorescent mercaptopurine based on intrinsically double emission carbon quantum dots. Image credit: Dzmitry Melnikau / Shutterstock.com
Quantum carbon dots were made from carbon sources (glutathione and formamide) using an easy microwave method. Monodisperse carbon quantum dots had a high affinity to 6-MP and exhibited dual fluorescence emission. The sensor response was optimized by adjusting the probe parameters (pH, temperature and volume).
Ratiometric fluorescence analysis showed a concentration range of 1.4 to 7.6 milligrams per liter 6-MP in aqueous solutions with a detection limit (LOD) of 1.3 milligrams per liter . Evaluation of sensor performance designed using human urine and plasma samples and complex solutions showed a recovery rate of 88 to 127%.
Quantum carbon points in fluorometric sensors
Quantum carbon dots are easy to prepare and have found their applications in optical and biomedical fields. The photoluminescence emission of carbon quantum dots and their easy surface functionalization make them a promising candidate for fluorometric optical sensors. While the surface functionalization of carbon quantum dots with hydroxyl, carboxyl, or carbonyl functional groups allows their easy dispersion in the aqueous medium, other functional fragments may facilitate analyte-based selectivity.
Consequently, several fluorometric sensors based on quantum carbon points were developed to determine the presence of various chemical and biochemical species. Because of their sensitivity, quantum carbon-based fluorometric sensors are considered better alternatives to conventional detection methods such as high-performance liquid chromatography (HPLC), Raman spectroscopy, electrophoresis, and spectrometry. masses.
In addition, fluorometric sensors avoid the requirements of expensive equipment, sophisticated sample preparation, expert operators and toxic solvents. In addition, ratiometric fluorescence sensors can measure intensities of multiple wavelengths with high accuracy and response stability, which is favorable for detecting various drug molecules.
Double-emission quantum carbon dots are more efficient than their single-wavelength counterparts and are prepared using the thermal or hydrothermal element doping method.
Ratiometric fluorescence based on quantum carbon points for 6 MP detection
In the present study, the ratiometric fluorescence detection technique developed to detect an immunosuppressive drug, 6-MP, used to treat autoimmune diseases and leukemia, was based on quantum carbon points. Too low or excessive presence of this drug in body fluids can cause serious health problems. Therefore, monitoring their levels in the human body is critical, which requires a robust analytical technique, which is highly sensitive to 6-MP.
The designed quantum carbon point-based fluorescence detection could analyze 6-MP in urine and human plasma samples. The quantum carbon points needed for the present study were prepared from glutathione and formamide by microwave-assisted synthesis. In addition, the synthesized quantum carbon dots were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS).
FT-IR spectroscopy revealed the surface chemistry of the synthesized quantum carbon points. The resulting spectra showed a wide absorption band between 3000-3500 centimeters inverse, corresponding to the stretching vibrations of hydroxyl (OH) and amine (NH). Peaks between 2800-2900 inverse centimeters were related to the stretching and bending vibrations of the methylene group (-CH2). The stretching vibration for carbonyl (C = O), alkene (C = C) and imide (C = N) was observed in the inverse of 1661.8 centimeters.
Stretch vibrations of amide (CN), alcohol (C-OH), and CO were observed at 1384.40, 1296.87, and 1047 inverse centimeters, respectively. Thus, the FT-IR spectra confirmed the presence of amide, hydroxyl and amine groups on the surface of the quantum carbon points. TEM images showed the encapsulation of the quantum carbon spot within the biological compounds used during their synthesis.
The average particle size of the carbon quantum dots was about 3 nanometers, indicating the success of the synthesis of ultra-small, monodisperse carbon quantum dots. In addition, XPS revealed the presence of sulfur and nitrogen groups at synthesized quantum carbon points that aided the interactions between the 6 MP drug and the carbon quantum dot probe.
Conclusion
In summary, 3 nanometer particle size quantum carbon points were prepared using an easy microwave method from glutathione and formamide. The prepared carbon quantum dots were selective to 6-MP and showed a dual fluorescence emission with a concentration range between 1.4 and 7.6 milligrams per liter.
The interactions between the 6 MP drug and the carbon quantum dot probe were due to the transmitted thiol and amine groups of glutathione. The fluorometric method measured the concentration of 6-MP in aqueous solutions with high accuracy and a LOD of 1.3 milligrams per liter. Despite the presence of interfering agents such as sodium sulfate (NaSO4), sodium chloride (NaCl), ferric chloride (FeCl3), arginine and fructose up to a concentration of 1000 milligrams per liter, the reported fluorometric method could maintain high precision.
The measurement of biological samples such as plasma and human urine with different concentrations of 6-MP using the fluorometric method based on carbon quantum dots resulted in drug recovery values in the range of 88 to 127%. The accuracy and reliability of the designed sensor performance were confirmed by performing intraday and interdia measurements. The dual fluorometric technique developed in the present work is a better alternative to the conventional methods used for the detection of drug molecules in an aqueous medium, with the possibility of adjusting the parameters to determine other biochemical or chemical species.
Reference
Saboorizadeh, B., Zare-Dorabei, R. (2022). Detection of selective fluorescent mercaptopurine based on intrinsically dual emission carbon quantum dots. ACS Science and Engineering of Biomaterials. https://pubs.acs.org/doi/10.1021/acsbiomaterials.2c00423
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