The artificial peroxidase activity of magnetic iron oxide nanoparticles and its application to glucose detection

Abstract

Aside from their superparamagnetic properties exploited in clinical magnetic resonance imaging (MRI), it was recently discovered that magnetic, iron oxide nanoparticles could function as an artificial, inorganic peroxidase. In this paper, we studied the impact of coating on the peroxidase activity of these nanoparticles. Nanoparticles with six different coating structures were synthesized and characterized by FTIR, TGA, TEM, size, zeta potential, and SQUID; and evaluated for peroxidase activity. Catalysis was found to follow Michaelis-Menten kinetics and peroxidase activity varied with respect to electrostatic affinity between nanoparticles and substrates, evidenced by differences in determined kinetic parameters. Glucose detection was selected as a model system because glucose could be indirectly measured from the release of hydrogen peroxide after its oxidation. Nanoparticles with high peroxidase activity exhibited higher sensitivity toward glucose, showing a larger linear slope when compared with those of low activity. A significantly improved linear correlation and detection limit of measured glucose could be readily obtained by manipulating the nanoparticle coating. Our findings suggest that iron oxide nanoparticles can be tailor-made to possess improved peroxidase-like activity. Such enhancements could further widen nanoparticle scope in glucose detection and extend its peroxidase functionality to other biomedical applications.

Accelerating peroxidase mimicking nanozymes using DNA

“…Using polymer coatings to modulate nanozymes activity was also reported in a few other systems. 14 In those examples, electrostatic interaction between Fe3O4 NPs and the substrates (TMB and ABTS) was found to be important for the enzyme activity. If TMB (positively charged) was used as a substrate, more negatively charged particles showed higher kcat values.…”

“…13 For practical applications and fundamental mechanistic understanding, factors affecting the peroxidase activity need to be fully addressed. [14][15][16][17] For example, the surface Fe 2+ content was found to be vital in its oxidation activity. 6 Prussian blue modified γ-Fe2O3 NPs have an elevated surface Fe 2+ content and thus a higher enzymatic activity.…”

“…If TMB (positively charged) was used as a substrate, more negatively charged particles showed higher kcat values. 14 In another example, Please do not adjust margins Please do not adjust margins DNA from PCR products was reported to inhibit ophenylenediamine oxidation, as the electrostatic interaction between the positively charged substrate and the negatively charged Fe3O4 NP surface is blocked by free DNA in solution and on particle surface. 36 To understand the mechanism here, we first studied whether H2O2 and TMB can compete with DNA adsorption.…”

“…15 Also, the role of surface charge on substrate oxidation was investigated and electrostatic interaction was found to be crucial for substrate binding. 14 The activity of unmodified NPs is often quite low, and an important challenge in this field is to promote their catalytic activity. We reason this goal might be achieved via understanding the surface chemistry of the reactions.…”

Catalytically Active Nanomaterials: Artificial Enzymes of Next Generation

“…In this context, merging nanotechnology with enzymology has paved a way to design novel multifunctional nanozymes exhibiting intrinsic biological enzyme-like activities. So far several types of nanomaterials such as gold (Au), Silver (Ag), Copper (Cu) nanoparticles (NPs), Cerium oxide (CeO 2 ), iron oxide, V 2 O 5 , Pt, Pd, graphene, fullerenes, and carbon nano tubes etc [7,[15][16][17][18][19][20][21][22][23][24]. have been investigated to possess the natural enzyme-like activities.…”