DESIGN AND PREPARATION OF CARBON NANODOTS FOR BIOMEDICAL APPLICATIONS

In the last few decades great efforts have been placed in studying carbon nanomaterials. Nowadays the nanocarbon family spans from fullerene, the first member, to Carbon Dots (C-Dots), the last to join. C-Dots have attracted considerable attention for a wide range of applications, especially bioapplications, because of their properties: emission, small sizes, aqueous solubility, biocompatibility and chemical stability. The aim of this doctoral thesis was to synthesize Carbon nanodots (CNDs), in particular nitrogen-doped CNDs, and functionalize their surface with properly designed molecules/biomolecules for bioapplications. In the first chapter, an introduction on the different types of C-Dots is provided, with a particular emphasis on CNDs. An overview of their most common production methods, characterization techniques and properties is given. A brief discussion on their applications, especially bioapplications, is reported. In chapter 2, highly fluorescent and water-soluble nitrogen-doped CNDs were prepared. A simple bottom approach by employing low-cost carbon and nitrogen sources (arginine and ethylenediamine) was used. The as-prepared CNDs were purified and characterized. They showed an excitation wavelength dependent emission, several functional groups on their surface such as amines and a narrow size distribution. Chapter 3 reported the covalent and non-covalent modification of CNDs in preparing hybrid materials for diverse bioapplications. The covalent modification of the CNDs surface with iron nanoparticles or drugs, such as paclitaxel and chlorambucil, was described. Moreover, it was studied the attachment of human serum albumin via noncovalent approaches. The Chapter 4 focused on the in vitro bioapplications of the materials described in chapter 3 as drug delivery systems, bioimaging agents and nanocarriers. Moreover, the effect of a protein corona around CNDs on their cellular uptake it was studied, since it is a prerequisite for their successful use for such applications. The CNDs and related materials presented non-toxicity, biocompatibility and good cellular imaging capability. They were tested through the IC50 and a high pharmacological activity in solid tumors was observed. Finally, their in vitro permeability was evaluated through an inverted BBB using a real-time cell response and observing that they are able to cross the BBB model.