Two biotinylated derivatives of the main hop chalcone xanthohumol (1) were prepared by a one-step synthesis via esterification using biotin and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC HCl) and 4-dimethylaminopyridine (DMAP) as coupling reagents. The products were characterized spectroscopically and their antiproliferative activity toward MCF-7, MCF-10A, HepG2, MDA-MB-231, 4T1 and Balb/3T3 cell lines was investigated using the SRB assay. For all three tested compounds the best activity was noted in the case of human (MCF-7) and mice (4T1) breast cancer cell lines (IC₅₀ values < 9 μM). Both biotinylated derivatives showed higher anticancer activity than xanthohumol (1) towards all types of tested breast cancer cells. Double biotinylated xanthohumol (3) proved to be the most active in inhibiting cell growth, with IC₅₀ values equal to 5.35 ± 1.5 μM for 4T1 and 8.03 ± 0.53 µM for MCF-7 cell lines. Compound 3 was also more active than 1 and 2 against liver cancer cells HepG2 (IC₅₀ = 17.37 ± 5.1 μM), while the IC₅₀ values for 1 and 2 were equal to 21.5 ± 2.7 and 22.1 ± 3.9 µM, respectively. 4‑O‑biotinylxanthohumol (2) was the second most active growth inhibitor, particularly with respect to MCF-7 (IC₅₀ = 6.19 ± 1.7 μM) and 4T1 (IC₅₀ = 6.64 ± 0.4 μM) cell lines. The antioxidant activity was evaluated using the 1.1-diphenyl-2-picrylhydrazyl radical (DPPH) method. All tested compounds (1-3) have antioxidant activity between 2.73 and 3.38 mM. It was reported for the first time that new prenylated chalcones containing the biotin moiety effectively inhibited proliferation of cancer cells in vitro.

The streptavidin and biotin interaction is one of the strongest non-covalent interactions in nature. As a result, this non-covalent interaction has been of great interest when it comes to biochemical assays, diagnosis of diseases, and cell-targeted drug delivery. Past research has proven that biotin-streptavidin is useful in biosensor development to improve the detection of a system when conjugated to nanoparticles. This study aims to prove that streptavidin-coated nanoparticles can be conjugated with biotinylated antibodies using the primary-secondary method to non-invasively detect adenocarcinoma in-vitro. While the use of nanoparticles is not uncommon to the diagnostics area of scientific research, the technique this research aims to investigate is a non-invasive one, utilizing the primary-secondary method. Specifically, the increased stability of fluorophores when bound to antibodies as opposed to nanoparticles directly can be indicative of the particles conjugated through the primary-secondary method’s ability to specifically bind to overexpressed transferrin receptors in the A549 cell line. In this paper, streptavidin-coated nanoparticles were conjugated with biotinylated anti-transferrin receptor antibodies and AlexaFluor-488 secondary antibodies were used to enable fluorescence-based detection. The efficiency of these particles were observed quantitatively through a plate reader and qualitatively through a fluorescence microscope. I demonstrated that these nanoparticles are able to specifically bind to the target proteins in this study. These findings contribute to the field of nanoparticle diagnostics and can be extended to different diseases caused by overexpression of proteins in the future. While this was conducted in-vitro, conjugates can be prepared to detect cancer in-vivo and can be tested with magnetic relaxometry in the future.