Physicochemical characteristics that affect carbon dot safety: Lessons from a comprehensive study on a nanoparticle...

Area of Science:

• Nanomedicine
• Materials Science
• Toxicology

Background:

• Carbon dots (CDs) are promising nanomaterials for medical and pharmaceutical applications.
• Understanding the safety profile of CDs is crucial for their clinical translation.
• Physicochemical properties are known to influence nanomaterial behavior and toxicity.

Purpose of the Study:

• To investigate how variations in physicochemical characteristics affect the safety of carbon dots.
• To synthesize and characterize a diverse library of carbon dots to establish structure-toxicity relationships.
• To identify key factors that determine the biocompatibility of carbon dots.

Main Methods:

• Synthesis of 35 distinct carbon dots with varying size, charge, composition, and surface coatings.
• Incubation of carbon dots with human macrophages at concentrations ranging from 3-200 µg/mL for 24 hours.
• Assessment of cell viability loss as a measure of carbon dot toxicity.

Main Results:

• Smaller carbon dots (10-20 nm) and aggregated nanoparticles exhibited higher toxicity than larger (40-100 nm) or dispersed ones.
• Increased positive charge, nitrogen content, and use of high molecular weight polyamines correlated with greater toxicity.
• Polyethylene glycol (PEG) decoration reduced the toxicity of cationic carbon dots.

Conclusions:

• Carbon dot toxicity is a multifactorial property influenced by size, aggregation, charge, nitrogen content, passivation agent, and synthesis method.
• Predicting carbon dot safety based on a single characteristic is challenging due to complex interactions.
• Tailoring carbon dot synthesis and surface modification is essential for optimizing their safety in biomedical applications.