Carbon Dots-BODIPY Nanohybrids For Photodynamic Therapy

Borondipyrromethane(BODIPY)is a kind of important organic fluorescent dyes,which has a broad application prospect in the field of photodynamic therapy.However,its biomedical application is seriously hindered due to the poor water solubility and low bioavailability.It is urgent to exploit a low toxicity and efficient nano delivery system to enhance the bioavailability of BODIPY and improve the effect of photodynamic therapy.Carbon dots(CDs)are a kind of potential drug carriers with many advantages,such as excellent luminescent properties,easy surface functionalization,strong hydrophilicity,good biocompatibility and low toxicity.In this paper,the CDs-BODIPY nanohybrids are constructed,which not only maintain the physical and chemical properties of BODIPY,but also improve the solubility and biocompatibility of BODIPY,and enhance the photodynamic treatment effect.The major content is as follows:(1)Preparation and characterization of red fluorescent CDs.CDs were synthesized from dopamine and o-phenylenediamine via a hydrothermal method.The size and morphology of CDs were analyzed by transmission electron microscopy(TEM).The results show that CDs are quasi-spherical nanoparticles with the average size of about 3.38 nm and have good monodispersity.CDs have four characteristic absorption peaks at 220,280,569,and 613 nm,which prove that CDs have a good light absorption capacity.In addition,CDs have the maximun emission at 650 nm and exhibit excellent fluorescence performance.(2)Assembly of CDs and BODIPY.CDs act as a carrier to assemble with BODIPY by nano-precipitation method to form nanocomposite materials(CBNPs).The loading rate of BODIPY in CBNPs was determined to be 71.25%.TEM proves that CBNPs have good monodispersity with the average size of 160.01 nm.(3)Fluorescence resonance energy transfer between CDs and BODIPY.The fluorescence spectrum of CDs has a good overlap with the absorption spectrum of BODIPY,which satisfies the precondition of fluorescence resonance energy transfer(FRET).Titration experiments have further proved that there is an interaction between CDs and BODIPY.In vitro singlet oxygen detection showed that CBNPs significantly increased the photodynamic effect of BODIPY.(4)Cell experiments of CBNPs.HeLa(human cervical cancer)cells were selected as the model cells,MTT assay,the living/dead cell staining experiment and the flow cytometry fully confirmed that CBNPs had higher phototoxicity than BNPs(BODIPY nanoparticles).The FRET effect between CDs and BODIPY greatly improves the photodynamic efficiency of BODIPY.This work opens up a new way to improve the bioavailability of hydrophobic functional materials,and expands the potential applications of CDs-based nanohybrids in the biomedical field.