Synthesis of Tunable and Multifunctional Ni-Doped Near-Infrared QDs for Cancer Cell Targeting and Cellular Sorting

Abstract

Here, we report the facile preparation of tunable magnetic Ni-doped near-infrared (NIR) quantum dots (MNIR-QDs) as an efficient probe for targeting, imaging, and cellular sorting applications. We synthesized the MNIR-QDs via a hot colloidal synthesis approach to yield monodisperse and tunable QDs. These hydrophobic QDs were structurally and compositionally characterized and further functionalized with amino-PEG and carboxyl-PEG to improve their biocompatibility. Since QDs are known to be toxic due to the presence of cadmium, we have evaluated the in vitro and in vivo toxicity of our surface-functionalized MNIR-QDs. Our results revealed that surface-functionalized MNIR-QDs did not exhibit significant toxicity at the concentrations used in the experiments and are therefore suitable for biological applications. For further in vitro applications, we covalently linked folic acid to the surface of amino-PEG-coated MNIR-QDs through NHS chemistry to target the folate receptors largely present in the HeLa cells to demonstrate the specific targeting and magnetic behavior of these MNIR-QDs. Improved specificity has been observed with treatment of HeLa cells with the folic acid-linked amino PEG-coated MNIR QDs (FA-PEG-MNIR-QDs) compared to the one without folic acid. Since the synthesized probe has magnetic property, we have also successfully demonstrated sorting between the cells which have taken up the probe with the use of a magnet. Our findings strongly suggest that these functionalized MNIR-QDs can be a potential probe for targeting, cellular sorting, and bioimaging applications.

Photoluminescent and superparamagnetic reduced graphene oxide–iron oxide quantum dots for dual-modality imaging, drug delivery and photothermal therapy

“…Quantum dots with magnetic properties (MQDs) can by synthesized by either doping conventional QDs (for example CdSe, or CdTe ) with metal elements like manganese [29], nickel [30], or gadolinium [31], or by encasing conventional QDs with IO [32] in silica spheres. These MQDs possess the photoluminescent properties of conventional QDs and the magnetic properties of the doping agent or the encapsulated IO, but they contain cytotoxic compounds such as cadmium selenium or cadmium telluride and are therefore cytotoxic without a biocompatible passivation coating [30].…”

“…These MQDs possess the photoluminescent properties of conventional QDs and the magnetic properties of the doping agent or the encapsulated IO, but they contain cytotoxic compounds such as cadmium selenium or cadmium telluride and are therefore cytotoxic without a biocompatible passivation coating [30]. The aim of this work was to synthesize magnetic graphene-IO quantum dots (herein MGQDs) as a multifunctional nanosystem for fluorescent imaging, M.R.I., targeted drug delivery and photothermal therapy for concurrent detection, monitoring and treatment of diseases.…”

Fe doped CdTeS magnetic quantum dots for bioimaging

“…Synthesis of magnetically doped core and core/shell MQDs, emitting in the visible regime and synthesized using non-aqueous solvents have been reported, for e.g. Co and Mn doped CdSe 31 , Cr doped CdSe 32 , Gd doped in CdSe 3 , Mn doped in CdSe 33 , Mn doped in the core of CdS/ZnS 34 and in the shell of core/shell CdSe/Zn 1 - x Mn x S 35 , Mn doped InP 36, 37 , Ni doped CdTeSe/CdS 38 . Many reports on the development of MQDs emitting in the visible regime are available, but very few exist 39 for bi-functional MQDs that emit in the NIR.…”

Near-infrared fluorescent probes in cancer imaging and therapy: an emerging field

“…When folic acid was covalently linked to these QDs, they exhibited improved specificity and unique magnetic properties. 76 In Gao's study, dendron-coated InP/ZnS core/shell NIR QDs featured high stability, low cytotoxicity, the ability of extravasation, and were a suitable size for kidney excretion. 77 Encapsulation of phosphorothiolated oligonucleotides (5-10 nucleotides) into the QD shell resulted in excellent chemical, photonic, and colloidal stability, high quantum yields, and tunable spectral emission.…”