New synthesis and biodistribution of the D-amino acid oxidase-magnetic nanoparticle system

Background: Application of nanoenzymes, based on D-amino acid oxidase (DAAO) conjugated to magnetic nanoparticles (NPs), as anticancer system requires improvement of the synthesis protocol and in vivo distribution evaluation. Results: A new and more efficient synthesis via EDC-NHS produced an Fe3O4NP-APTES-DAAO system with a specific activity of 7 U/mg NPs. IR spectroscopy showed that all Fe3O4 NP sites are saturated with APTES and all available NH2 sites with DAAO. The acute cytotoxicity of the new system does not differ from that of the previous one. In vivo experiments showed that the system did not cause adverse effects, cross the brain-blood barrier and accumulate in the heart. Conclusions: Our results support the possibility to use enzymes conjugated to magnetic NPs for cancer treatment. Besides, we think that enzymes and other biological molecules efficiently conjugated to magnetic NPs might constitute a category of 'bionanoparticles' to be exploited, not only in medical, but also in industrial biotechnology. Lay abstract: We have linked magnetic nanoparticles to D-amino acid oxidase, an enzyme capable of producing, in the presence of its substrate, reactive oxygen species. The scope is to use the magnetic properties of the enzyme-nanoparticle system to direct it to a desired area where its cytotoxicity can be controlled by the addition of exogenous substrate. Besides the possible applications in cancer therapy, we think that enzymes and other biological molecules linked to magnetic nanoparticles might also be exploited in industrial biotechnology.