Polyethyleneimine modified fluorescent carbon dots and their application in cell labeling

Area of Science:

• Materials Science
• Nanotechnology
• Biochemistry

Background:

• Fluorescent nanoparticles are crucial for bioimaging.
• Carbon dots (CDs) offer a promising alternative to traditional quantum dots due to their low toxicity.
• Enhancing the fluorescence properties and biocompatibility of CDs is an active area of research.

Purpose of the Study:

• To synthesize and characterize novel fluorescent carbon dots (CDs) from glucose.
• To improve the fluorescence intensity and quality of CDs through polyethyleneimine (PEI) modification.
• To evaluate the potential of PEI-modified CDs for in vitro cell labeling and imaging, and assess their cytotoxicity.

Main Methods:

• Solvothermal synthesis of carbon dots using glucose in a water-glycol medium.
• Modification of carbon dots with polyethyleneimine (PEI).
• Characterization of carbon dot properties, including size, fluorescence, and quantum yield.
• Conjugation of modified CDs with CEA8 antibody for cell labeling.
• In vitro cytotoxicity assays using HeLa cells.

Main Results:

• Monodispersed spherical carbon dots with a diameter of approximately 7.5 nm were synthesized.
• PEI modification resulted in a 300-fold enhancement of fluorescence intensity and a red shift in emission wavelength.
• The modified CDs exhibited excitation wavelength-dependent fluorescence with a quantum yield of 3.5%.
• PEI-modified CDs successfully labeled and imaged HeLa cells in vitro.
• No apparent cytotoxicity was observed for the modified CDs in HeLa cells.

Conclusions:

• Polyethyleneimine modification significantly enhances the fluorescence properties of carbon dots.
• These enhanced carbon dots demonstrate excellent biocompatibility and biosafety, outperforming CdTe quantum dots.
• The developed carbon dots are suitable for in vitro cell labeling and imaging applications, offering a safer alternative in nanomedicine.