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To date, there are no preoperative and quantitative dynamics in clinical practice that can reliably differentiate between a benign and malignant renal cell carcinoma (RCC). For monitoring different analytes in body fluids, more than 40 different molecular biomarkers have been identified, however, they are associated with limited clinical sensitivity and/or non-optimal specificity due to their leaky nature. Previous work on RCC demonstrated the miRNA15a to be reliable and novel biomarker with 98.1% specificity and 100% sensitivity. Despite the high potential of miRNA15a biomarker, its clinical application is considerably hampered by the insensitive nature of the detection methods and low concentration of biomarker in samples that is aggravated by the high level of contamination due to other solutes present in body fluids. In this work, a non-invasive quantitative approach is demonstrated to overcome such diagnostics issues through biotin-streptavidin binding and fluorescence active magnetic nanocarriers that ensured prompt isolation, enrichment and purification of the biomarker miRNA15a from urine. The study demonstrates that detectable low levels of these miRNAs through miRNA capturing nanocarriers can potentially function as advanced diagnostic markers for the non-invasive investigation and early detection of renal cancer.

Surface modification of nanocarriers enables selective attachment to specific molecular targets within a complex biological environment. Besides the enhanced uptake due to specific interactions, the surface ligands can be utilized for radiolabeling applications for bimodal imaging ensured by positron emission topography (PET) and magnetic resonance imaging (MRI) functions in one source. Herein, we describe the surface functionalization of magnetite (Fe 3 O 4 ) with folic acid as a target vector. Additionally, the magnetic nanocarriers were conjugated with appropriate ligands for subsequent copper-catalyzed azide-alkyne cycloaddition or carbodiimide coupling reactions to successfully achieve radiolabeling with the PET-emitter 18 F. The phase composition (XRD) and size analysis (TEM) confirmed the formation of Fe 3 O 4 nanoparticles (6.82 nm ± 0.52 nm). The quantification of various surface functionalities was performed by Fourier-transform infrared spectroscopy (FT-IR) and ultraviolet-visible microscopy (UV-Vis). An innovative magnetic-HPLC method was developed in this work for the determination of the radiochemical yield of the 18 F-labeled NPs. The as-prepared Fe 3 O 4 particles demonstrated high radiochemical yields and showed high cellular uptake in a folate receptor overexpressing MCF-7 cell line, validating bimodal imaging chemical design and a magnetic HPLC system. This novel approach, combining folic acid-capped Fe 3 O 4 nanocarriers as a targeting vector with 18 F labeling, is promising to apply this probe for bimodal PET/MR-studies.