Preparation of Graphene Composite and Its Application in the Detection of Tumor Markers

Pancreatic cancer is a malignant tumor with high mutation rate of K-ras oncogene. Therefore, a material capable of detecting the expression of K-ras oncogene was prepared, and it was expected to realize the early diagnosis and treatment of cancer. Graphene quantum dots (GQDs), as a new carbon nanomaterial, has good optical stability and low toxicity biocompatibility. However, pure GQDs has the defect of low quantum yield, which limits its application in ultra-sensitive detection. To enhance quantum yield of GQDs, nitrogen atoms were introduced into GQDs to obtain nitrogen-doped GQDs (N-GQDs). Compared with the unalloyed GQDs, the electrochemical luminescence (ECL) efficiency of the doped N-GQDs was improved greatly. Through the analysis of its ECL mechanism, the deoxyribonucleic acid (DNA) was adopted as the connecting medium to adjust the distance between the GQDs and Aurum nanoparticles (AuNPs). Based on the energy transfer between GQDs and AuNPs, the change of ECL signal of GQDs was controlled. On the basis of this theory, N-GQDs@AuNPs-ssDNA composite was constructed, its morphology and chemical composition were characterized by various means, and its ECL properties were analyzed. Ultraviolet visible (UV-Vis) absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) results showed that the graphene composite N-GQDs@AuNPs was successfully prepared. UV-Vis spectroscopy showed that the probe DNA was connected to AuNPs, which indicated that the production of N-GQDs@AuNPs-ssDNA was successfully realized. N-GQDs/AUNPs-ssDNA and target K-ras DNA were incubated at 37 C for 1 h to achieve DNA double-stranded hybridization. The results showed that the graphene composites prepared in this study could be used to quantitatively determine the target K-ras tumor markers.