Nanoparticles have been extensively developed and studied in biomedical sciences for various applications, including drug delivery, cell targeting, bioimaging, and diagnosis. Carbon-based nanoparticles, particularly carbon dots (CDs), have gained significant attention due to their unique physicochemical properties such as fluorescence, high photostability, water solubility, non-toxicity, biocompatibility, and environmental friendliness, and their ease of synthesis and cost-effectiveness making them highly suitable for biomedical applications, as bioimaging agents, biosensors, theranostic tools, and drug delivery systems.
The surface functional groups of CDs play a crucial role in their potential as drug carriers, particularly in targeting cancer cells such as glioblastoma. Their small size, high surface area, and tunable surface chemistry allow them to efficiently interact with biological membranes, facilitating targeted drug delivery. Therefore, understanding the interactions between CDs and phospholipid vesicles is critical for optimizing their function in drug delivery applications.
One of the key objectives of this study is to achieve precise control over CD size, as it significantly influences their physicochemical properties and interactions with lipid membranes. CDs are synthesized using a one-step hydrothermal method, in which an ascorbic acid solution is heated at high temperatures (>150°C) in an autoclave reactor under high pressure. By carefully adjusting temperature and reaction time, fluorescent CDs of different sizes can be produced. Notably, 5 nm CDs have demonstrated promising potential for biomedical applications, particularly in drug delivery and theranostics.
To better understand the behavior of CDs in biological systems, it is essential to study their interactions with biological membranes. However, investigating these interactions in live cells presents challenges due to the complexity of cellular environments. Therefore, model membranes provide an effective alternative, allowing for precise characterization of CD-membrane interactions under controlled experimental conditions. Phospholipid vesicles, which serve as simplified models of biological membranes, enable researchers to examine how nanoparticles affect membrane fluidity, permeability, and protein interactions.
In this study, POPC phospholipid vesicles are used as model membranes to investigate the interactions between CDs and lipid bilayers. POPC is a major component of biological membranes and is widely used in biophysical studies due to its well-characterized structural and dynamic properties. By examining how CDs interact with POPC vesicles, this study aims to elucidate the fundamental mechanisms governing nanoparticle-membrane interactions, which is critical for optimizing their use in drug delivery and other biomedical applications.
Previous studies have documented interactions between nanoparticles and phospholipid vesicles, though research on CD-vesicle interactions remains limited. Most existing studies focus on hydrophobic CDs or CDs covalently attached to phospholipids as vehicles for studying bilayer dynamics. Additionally, nitrogen-doped CDs with positive surface charges have been shown to interact with negatively charged liposomes, affecting the structural, thermodynamic, and permeability properties of the bilayer, suggesting partial embedding of CDs within the membrane. However, there is a lack of research on hydrophilic CDs and their interactions with phospholipid vesicles, highlighting the need for further investigation.
A thorough understanding of these physicochemical interactions is crucial for optimizing CDs as drug carriers, ensuring efficient and targeted drug delivery while preserving membrane integrity, enhancing therapeutic efficacy, and minimizing adverse effects. Preliminary findings from our research indicate that 5 nm CDs successfully interact with phospholipid vesicles, facilitating their incorporation into the bilayer. This interaction appears to induce vesicle remodeling, leading to vesicle splitting and the formation of CD-phospholipid vesicle complexes. Further studies will be conducted to optimize the composition and physicochemical properties of CDs and phospholipid vesicles, with the goal of developing an efficient and targeted drug delivery system.