Chiral Near-Infrared ?-HgS Quantum Dots And Its Application In Photothermal Therapy

In recent years,near-infrared quantum dots(NIR QDs)have better optical,electrical,mechanical and other properties than macro-materials which have always been the focus of the research,and they have extensive applications in the fields of fluorescent labeling,bio-imaging and optoelectronic devices.Fluorescence based on NIR QDs has a certain displacement with biological tissue autofluorescence,which penetrate deeper into the tissue,and has better renal clearance rate,lower detection threshold concentration and the better targeting effects.NIR QDs have been used in large number of studies about bio-imaging and cancer treatment.And the mercury-based chalcogenide QDs are relatively unopened NIR QDs,the mercury-based chalcogenide QDs with chiral optical properties have not been reported yet.In this paper,chiral L/D-cysteine(L/D-Cys)enantiomers are used as ligands for modificating on the surface of ?-HgS NIR QDs firstly.Chiral ligand modified ?-HgS NIR QDs were synthesized and their potential applications in photothermal therapy were studied for the first time.To broaden the types of mercury-based chalcogenide NIR QDs,the indium(In)doped ?-HgS NIR QDs were synthesized based on chiral ligands modified?-HgS NIR QDs.The research content is mainly divided into the following three parts:(1)Research on the synthesising of L/D-Cys modified ?-HgS NIR QDs and their chirality originChiral ?-HgS QDs with near-infrared fluorescence were synthesized by grafting the chiral enantiomer L/D-Cys onto the surface of ?-HgS in the aqueous solution.The two chiral ?-HgS NIR QDs both had small particle size and uniform dispersion(around 3.5 nm),showed strong near-infrared plasmon resonance absorption peak(780 nm),and fluorescence emission peak could be adjustable in the near-infrared region(900-1000 nm).By the combination of surface chiral L/D-Cys ligands and Hg atoms,the chiral ligands were complexed with the surface Hg atoms to induce chiral signals of ??HgS QDs which have no chirality themselves.The two chiral ?-HgS NIR QDs showed exhibit standard mirror symmetry and reversed compared to the corresponding chiral ligands in circular dichroism spectra.(2)Potential application of L/D-Cys modified ?-HgS NIR QDs in photothermal therapyChiral L/D-Cys modified ?-HgS NIR QDs were relatively undeveloped near-infrared material,and they have no corresponding practical application yet.Because of their strong near-infrared plasmon resonance absorption peak at 780 nm,a series of analyses were carried out on the photothermal properties of chiral ?-HgS NIR QDs.We found that they have the potential to be used as novel photothermal therapeutic agents applied in photothermal therapy.Therefore,the absorbance of the chiral L/D-Cys modified ?-HgS QDs in the near-infrared region was measured using visible near-infrared absorption spectroscopy.The photothermal conversion performance of quantum dots were tested by photothermal heating curves of chiral L/D-Cys modified?-HgS NIR QDs in vitro.The photothermal conversion efficiencies of chiral L/D-Cys modified ?-HgS NIR QDs were 29.32%and 30.85%,respectively.At the same time,the cytotoxicity of chiral ?-HgS QDs was also evaluated.No significant toxicity was shown of chiral ?-HgS NIR QDs(100 mg·L-1)both in rat adrenal medullary chromoblastoma cell line(PC 12 cell)and human cervical cancer cell line(HeLa cell).(3)Synthesis and characterization of In doped chiral ?-HgS NIR QDsBased on the preparation of the L-Cys modified chiral ?-HgS NIR QDs synthesized by our previous method,we infused indium chloride(InC13)into ?-HgS NIR QDs to prepare In doped chiral ?-HgS NIR QDs.Indium was successfully doped into ?-HgS QDs which could be tested by X-ray energy spectroscopy(EDS)and X-ray photoelectron spectroscopy(XPS).The high-angle annular dark field(HAADF),atomic force microscopy(AFM)and dynamic light scattering(DLS)determined that the morphology and particle size of In-doped chiral ?-HgS NIR QDs were larger than those of L-Cys modified chiral ?-HgS QDs.Powder crystal X-ray diffraction(XRD)showed that the crystallinity of the prepared In doped chiral ?-HgS NIR QDs was better than that of undoped ?-HgS NIR QDs.Mercury chalcogenide nanomaterials are relatively unopened NIR QDs,and In doped chiral ?-HgS NIR QDs broadened the types of such NIR QDs.