Tailoring of polymeric carbon dots by using organic dyes for radical scavenging

Carbon dots (CDs) are emerging as versatile fluorescent nanomaterials due to their excellent properties such as high-water solubility, photostability, good biocompatibility, flexibility for surface modification, low toxicity and production costs. These characteristics make them preferable to their inorganic cousins Quantum Dots (QDs) and more suitable for biomedical applications, such as imaging, antibacterial therapy, drug delivery for cancer treatment, photodynamic therapy and antioxidative nanotechnology. Regarding the last field, CDs have proven to possess scavenging activity towards reactive oxygen species (ROS), which are chemical, highly reactive, oxygen-containing species including hydroxyl radical , singlet oxygen, superoxide anion, and hydrogen peroxide. This antioxidant capability allows CDs to act as effective agents capable of keeping the concentration of ROS low, preventing various diseases such as cancer, atherosclerosis, neurological disorders, asthma, hypertensions, local anaphylaxis or inflammation. In this thesis work, three different types of CDs were synthetized by ultrasonic-assisted method using Citric Acid (CA) and p-Phenylendiamine (DPA) as precursors. First of all, pristine CDs with only CA and DPA as reagents were synthesized. Then, two organic dyes, Methylene Blue (MB) and Cochineal Red (CR) were added keeping the other two precursors and the synthesis method unchanged, in order to create more performant CDs (second and third type respectively) for what concern scavenging activity and red-shifted fluorescence emission, resulting in less energy been released and making them hopefully more suitable for biomedical field. All CDs were characterized through different spectroscopic techniques in order to investigate structural and photophysical properties of the three types of CDs obtained. Lastly, solutions of CDs and another organic dye (Curcumin) were prepared in order to investigate and evaluate CDs scavenging activity.