Highly Sensitive Detection of Glucose by a "Turn-Off-On" Fluorescent Probe Using Gadolinium-Doped Carbon Dots and Carbon Microparticles.

Carbon dots, as a potential substitute for semiconductor quantum dots, have drawn great interest in recent years. The preparation of fluorescent carbon dots has been made easy with many significant advances, but the complicated purifying processes, low quantum yield, and blue emission wavelength still limit its wider application in biosensors, biomedicine, and photonic devices. Here we report a strategy to synthesis Gd-doped carbon dots (Gd-Cdots) of super-high quantum yield with a microwave assisted hydrothermal method. The Gd-Cdots, with a diameter of 47∼8 nm, can be purified easily with conventional centrifugal techniques. Carbon microparticles (CMPs) have also been synthesized with a similar procedure. Meanwhile, we demonstrated a novel "turn-off-on" fluorescent biosensor, which has been developed for highly sensitive detection of glucose using Gd-doped carbon dots as probes. The proposed biosensor has exhibited low-cost and non-toxic properties, with high sensitivity and good specificity. In addition, the results in real blood samples further confirmed it as a promising application in diabetes diagnosis.