Demir oksit bazlı özgün teranostik nanoparçacıkların geliştirilmesi

Superparamagnetic iron oxide nanoparticles (SPIONs) constitute popular nano-platforms in the continuously improving field of nanomedicine providing magnetic field dependent response. They are frequently investigated for opportunity for drug delivery, magnetic resonance imaging (MRI), hyperthermia and tissue engineering. Such popularity of SPIONs partially originates from their high biocompatibility. Indeed, SPIONs are the only clinically approved metal oxide nanoparticles. The ease of preparation, non-invasive diagnostic capability and suitability for further surface chemistries are another set of advantages in the medical field. All these properties make them potentially theranostic nanoparticles which can be adopted in various therapeutic and diagnostic modes of action in medicine but there seems to be more to explore in these novel compositions. First part of this thesis summarizes the discovery of the intrinsically luminescent polyethyleneimine (PEI) coated SPIONs which provides gene-delivery combined with bimodal imaging modality. Such compositions have been studied frequently as transfection agents but their luminescence potential has never been considered or recognized before. Here, it will be shown that there is a tremendous and method dependent improvement in the poor blue luminescence of branched polyethyleneimine (bPEI) when coated on the surface of SPIONs. This novel finding is interesting especially when the quenching capability of iron oxide core in the visible range of the electromagnetic spectrum is taken into account. Carefully conducted spectroscopic and theoretical studies in this thesis tried to uncover the origin of such enhancement and provide an important contribution to the literature of luminescent polyamines. Ultimately, the amine oxidation, the restriction of bPEI upon its surface adsorption coupled with final acidification is the major combinatory factor behind such a strong emission observed from bPEI-SPIONs. Besides, the transfection study of therapeutic oligonucleotide, poly I:C to the cervical cancer cell line HeLa demonstrated the potential theranostic utility of such nanoparticles. In short, this crucial finding, which is about the widely used bPEI coated SPIONs in the nanomedicine, both serves as a conceptual improvement in the literature of the fluorescent polyamines and enhances the scope of bPEI-SPIONs by showing their new diagnostic capability. Second part of this thesis is devoted to an effort to develop a non-toxic, non-cationic, protein based transfection agent containing SPIONs as the carrier and signaling moiety. One of the most significant obstacles in the field of nanomedicine is the restriction of the gene carrier nanoparticles to the toxic poly-cationic compositions in order to improve their gene loading efficiency. This is a major drawback which particularly frustrates the notable biocompatibility of SPIONs. Therefore, safer and highly functional SPION based gene carrier designs need to be developed by excluding polycations to take advantage of the biocompatibility of iron oxide core to the full extend. With regards to this current problem, this thesis will demonstrate the development of a novel and multifunctional SPION based miRNA delivery agent utilizing a natural miRNA carrier protein Argonaute 2 (AGO2) inspired by the natural miRNA carrying capability of AGO2 in the extracellular media. The ultimate nanoparticle was designed as AGO2 conjugated SPIONs tagged with an affinity tag (antiHer2 protein) and a far red emissive fluorescent tag (Cy5) to achieve a selective and image guided delivery of autophagy related miR376 therapeutics to the breast cancer models. At the second part of the thesis, the development of the small and colloidally stable AGO2 and antiHer2-dye conjugated SPIONs were discussed with an optimized protocols. These nanoparticles show an excellent in vitro and in vivo biocompatibility and imaging guided in vitro and in vivo targeted delivery to the MDA-MB-453 and SKBR3 breast cancer cell lines. Besides, their capability for the delivery of miR376b mimics was confirmed by in vitro analysis on MDA-MB-453 and SKBR3 which shows an increase in the level of native miR376b transcription. This work provides a first example to non-cationic, protein based SPION-transfection agent and miRNA-AGO2 complexation outside the biological environment. Third part of this thesis work focuses on the delivery of SPION-based transfection agents to tumor tissue under the consideration of the intra-tumor heterogeneity. The molecular targeting of the therapeutics to the desired tissue is a new approach which reduces the side effects of therapeutics and improves their therapeutic efficiency. However, the tumors, especially those possessing the multiple molecular cues such as breast cancer, are heterogeneous and the cells even within the same tumor may show the overexpression of different receptors. In order to enhance the targeting efficiency of heterogeneous tumors, SPION immuno-conjugates which combine the antibodies sensing the overexpressed Her2 and EGFR signaling receptors on the surface of the breast cancer cells were developed in this thesis. Beside their specific molecular targeting capability, SPION immuno-conjugates take advantage of the superparamagnetic iron oxide core and can be directed under magnetic field which provides magnetic targeting as well. Bispecific SPION immuno-conjugates are anionic, colloidally stable and small enough to circulate in the body. Targeting different breast tumor cell lines with such SPIONs are demonstrated in vitro. This approach contributes to a newly developing area of targeting nanoparticles to tumor heterogeneity. In a conclusion, this thesis aimed to contribute to the literature of SPION based theranostics by providing new diagnostic capabilities, improving the biocompatibility and strengthening the molecular targeting issues.