The Impact of Amine-Functionalised Iron Oxide Nanoparticles on the Menaquinone-7 Isomer Profile and Production of the Bioactive Isomer

Abstract

AbstractThe K family of vitamins includes a collection of molecules with different pharmacokinetic characteristics. Menaquinone-7 (MK-7) has the finest properties and is the most therapeutically beneficial due to its long plasma half-life and outstanding extrahepatic bioavailability. MK-7 exhibits cis–trans isomerism, and merely the all-trans form is biologically efficacious. Therefore, the remedial value of MK-7 end products is exclusively governed by the quantity of all-trans MK-7. Consumers favour fermentation for the production of MK-7; however, it involves several challenges. The low MK-7 yield and extensive downstream processing requirements increase production costs, resulting in an expensive final product that is not universally available. Bacterial cell immobilisation with iron oxide nanoparticles (IONs) can potentially address the limitations of MK-7 fermentation. Uncoated IONs tend to have low stability and can adversely affect cell viability; thus, amine-functionalised IONs, owing to their increased physicochemical stability and biocompatibility, are a favourable alternative. Nonetheless, employing biocompatible IONs for this purpose is only advantageous if the bioactive MK-7 isomer is obtained in the most significant fraction, exploring which formed the aim of this investigation. Two amine-functionalised IONs, namely 3-aminopropyltriethoxysilane (APTES)-coated IONs (IONs@APTES) and L-Lysine (L-Lys)-coated IONs (L-Lys@IONs), were synthesised and characterised, and their impact on various parameters was evaluated. IONs@APTES were superior, and the optimal concentration (300 $$\upmu$$ μ g/mL) increased all-trans MK-7 production and improved its yield relative to the untreated cells by 2.3- and 3.1-fold, respectively. The outcomes of this study present an opportunity to develop an innovative and effective fermentation method that enhances the production of bioactive MK-7.