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Amplified Peroxidase-Like Activity in Iron Oxide Nanoparticles Using Adenosine Monophosphate: Application to Urinary Protein Sensing

Yang, Ya-Chun, Wang, Yen-Ting, Tseng, Wei-Lung
ACS Applied Materials & Interfaces 2017 v.9 no.11 pp. 10069-10077
DNA, adenosine, adenosine diphosphate, adenosine monophosphate, adenosine triphosphate, adsorption, catalytic activity, fluorescence, histidine, hydrogen peroxide, iron oxides, nanoparticles, oxidation, peroxidase, phosphates
Numerous compounds such as protein and double-stranded DNA have been shown to efficiently inhibit intrinsic peroxidase-mimic activity in Fe₃O₄ nanoparticles (NP) and other related nanomaterials. However, only a few studies have focused on finding new compounds for enhancing the catalytic activity of Fe₃O₄ NP-related nanomaterials. Herein, phosphate containing adenosine analogs are reported to enhance the oxidation reaction of hydrogen peroxide (H₂O₂) and amplex ultrared (AU) for improving the peroxidase-like activity in Fe₃O₄ NPs. This enhancement is suggested to be a result of the binding of adenosine analogs to Fe²⁺/Fe³⁺ sites on the NP surface and from adenosine 5′-monophosphate (AMP) acting as the distal histidine residue of horseradish peroxidase for activating H₂O₂. Phosphate containing adenosine analogs revealed the following trend for the enhanced activity of Fe₃O₄ NPs: AMP > adenosine 5′-diphosphate > adenosine 5′-triphosphate. The peroxidase-like activity in the Fe₃O₄ NPs progressively increased with increasing AMP concentration and polyadenosine length. The Michaelis constant for AMP attached Fe₃O₄ NPs is 5.3-fold lower and the maximum velocity is 2.7-fold higher than those of the bare Fe₃O₄ NPs. Furthermore, on the basis of AMP promoted peroxidase mimicking activity in the Fe₃O₄ NPs and the adsorption of protein on the NP surface, a selective fluorescent turn-off system for the detection of urinary protein is developed.