Fig. 33. (A) Schematic illustration showing the multicolored P-QD- and N, S-codoped rGO-(N, S-rGO) based DNA biosensor for the sensitive detection of HBV DNA and HIV DNA. [Reprinted with permission from ref. 711, L. Chen, L. Song, Y. Zhang, P. Wang, Z. Xiao, Y. Guo and F. Cao, Nitrogen and Sulfur Codoped Reduced Graphene Oxide as a General Platform for Rapid and Sensitive Fluorescent Detection of Biological Species, ACS Appl. Mater. Interfaces, 2016, 8, 11255–11261. Copyright© American Chemical Society.] (B) Schematic illustration of the FRET-based biosensing platform using GQDs and pyrene-functionalized molecular beacon probes for miRNA detection. [Reprinted with permission from ref. 712, H. Zhang, Y. Wang, D. Zhao, D. Zeng, J. Xia, A. Aldalbahi, C. Wang, L. San, C. Fan, X. Zuo and X. Mi, Universal Fluorescence Biosensor Platform Based on Graphene Quantum Dots and Pyrene-Functionalized Molecular Beacons for Detection of MicroRNAs, ACS Appl. Mater. Interfaces, 2015, 7, 16152–16156. Copyright© American Chemical Society.] (C) Aptamer biosensor based on a NA/AgNC/GO hybrid system for the detection of thrombin. [Reprinted with permission from ref. 681, X. Liu, F. Wang, R. Aizen, O. Yehezkeli and I. Willner, Graphene Oxide/Nucleic-Acid-Stabilized Silver Nanoclusters: Functional Hybrid Materials for Optical Aptamer Sensing and Multiplexed Analysis of Pathogenic DNAs, J. Am. Chem. Soc., 2013, 135, 11832–11839. Copyright© American Chemical Society.] (D) Schematic representation showing the mechanism of UC NPs/GO in the presence and absence of complementary DNA. [Reprinted with permission from ref. 713, P. Alonso-Cristobal, P. Vilela, A. El-Sagheer, E. Lopez-Cabarcos, T. Brown, O. L. Muskens, J. Rubio-Retama, A. G. Kanaras, Highly Sensitive DNA Sensor Based on Upconversion Nanoparticles and Graphene Oxide, ACS Appl. Mater. Interfaces, 2015, 7, 12422–12429. Copyright© American Chemical Society.].