No abstract

A highly stable bimodal indium(111) radiolabeled indium QDs were synthesized for in vivo SPECT/fluorescence imaging.

Surface functionalization of nanoparticles is an important determinant of their interactions with biological compartments at the nano-bio interface. In this paper, a series of multidentate zwitterionic polymeric ligands were synthesized and used to functionalize the surface of quantum dots (QDs). The structure of polymer ligands was designed by changing the molar ratio of reactants and precursors used in the reaction. A three-component micro-emulsion method was developed to improve the efficiency of ligand exchange and avoid cross-linking reactions. Highly stable, compact and biocompatible zwitterionic QDs with different surface charge densities were obtained after ligand exchange. Variation of the surface charge density of QDs was verified by zeta potential measurements. The interaction of zwitterionic QDs with different cancer and normal cell lines (KB 3-1, COLO 205 and HEK 293) was surface charge density dependent. From cell viability studies, it was shown that higher surface charge density resulted in lower cytotoxicity of zwitterionic QDs when incubated with both cancer and normal cell lines. Furthermore, the feasibility of conjugating functionalized QDs (coated with amine zwitterionic polymer ligands) with a biomolecule was demonstrated. This was exemplified by the conjugation of amine zwitterionic QDs with a cRGD peptide, which showed improved interaction of cRGD-QDs with a n b 3 integrin receptors expressed on U87MG glioblastoma tumor cells. Engineering the surface charge density and functionalization of nanoparticles, by multidentate zwitterionic ligands, provides a strategy to tune the surface properties of QDs, which impacts their cytotoxicity and cellular interaction at the nano-bio interface.

The overall objective of this study is to non-invasively image and assess tumor targeting and retention of directly labeled T-lymphocytes following their adoptive transfer in mice. T-lymphocytes obtained from draining lymph nodes of 4T1 (murine breast cancer cell) sensitized BALB/C mice were activated in-vitro with Bryostatin/Ionomycin for 18 hours, and were grown in the presence of Interleukin-2 for 6 days. T-lymphocytes were then directly labeled with 1,1-dioctadecyltetramethyl indotricarbocyanine Iodide (DiR), a lipophilic near infrared fluorescent dye that labels the cell membrane. Assays for viability, proliferation, and function of labeled T-lymphocytes showed that they were unaffected by DiR labeling. The DiR labeled cells were injected via tail vein in mice bearing 4T1 tumors in the flank. In some cases labeled 4T1 specific T-lymphocytes were injected a week before 4T1 tumor cell implantation. Multi-spectral in vivo fluorescence imaging was done to subtract the autofluorescence and isolate the near infrared signal carried by the T-lymphocytes. In recipient mice with established 4T1 tumors, labeled 4T1 specific T-lymphocytes showed marked tumor retention, which peaked 6 days post infusion and persisted at the tumor site for up to 3 weeks. When 4T1 tumor cells were implanted 1-week post-infusion of labeled T-lymphocytes, T-lymphocytes responded to the immunologic challenge and accumulated at the site of 4T1 cell implantation within two hours and the signal persisted for 2 more weeks. Tumor accumulation of labeled 4T1 specific T-lymphocytes was absent in mice bearing Meth A sarcoma tumors. When lysate of 4T1 specific labeled T-lymphocytes was injected into 4T1 tumor bearing mice the near infrared signal was not detected at the tumor site. In conclusion, our validated results confirm that the near infrared signal detected at the tumor site represents the DiR labeled 4T1 specific viable T-lymphocytes and their response to immunologic challenge can be imaged in vivo.