Biotinylated magnetic nanoparticles for pretargeting: synthesis and characterization study

In this paper, we have proposed a simple method to covalently conjugate biotin to magnetic nanoparticles, which can be targeted to the tumour sites by using pretargeting approach with avidin or streptavidin. Magnetic nanoparticles of manganese ferrite were synthesized by alkaline coprecipitation of ferric chloride hexahydrate, ferrous sulphate heptahydrate and manganese sulphate monohydrate using ammonium hydroxide. The synthesized magnetic nanoparticles were then successfully surface modified by using 3-aminopropyl trimethoxysilane, and the amount of aminopropylsilane bound to the surface of magnetic nanoparticles was quantified by measuring the absorbance of a purple-coloured complex (Ruhemann's purple) formed between amine group and ninhydrin at 576 nm. The aminated magnetic nanoparticles were then conjugated to biotin by reacting them with N-hydroxysuccinimide-biotin in dimethylsulphoxide. The successful conjugation of biotin to magnetic nanoparticles was confirmed by Fourier transform infrared spectroscopy. The size, phase and magnetic nature of the synthesized nanoparticles were analysed by using various techniques like transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy and vibrating sample magnetometry.