title: Label-free, nucleotide-mediated dispersion of magnetic nanoparticles for "non-sandwich type" MRI-based quantification of enzyme.
abstract: In the present work, we demonstrate that nucleotide can adsorb efficiently on the surface of carboxylic acid-functionalized nanoparticles and stabilize the particles against aggregation. In the present study we take magnetic nanoparticles (MNPs), manganese oxide nanoparticles (MnO), and upconversion nanophosphors (UCNPs) as models. The result shows that not only MNPs, but also other kinds of nanoparticles that have similar surface properties can be dispersed and stabilized by nucleotides. Interestingly, adenosine bearing different numbers of phosphate groups has distinct stabilizing effect. On the basis of this observation, we developed a magnetic relaxation-based enzyme assay for quantitative analysis of alkaline phosphatase. A detection limit of 0.002 U/μL for calf intestine alkaline phosphatase (CIAP) could be obtained, which is lower than the gold nanoparticle-based colorimetric method. In contrast to the conventional magnetic relaxation switches (MRSw), this assay was achieved without covalent modification and separation steps, sandwich type binding was not required as well, which would potentially expand the application of magnetic relaxation-based analysis.
authors.affiliation: Department of Chemistry and Institutes of Biomedical Sciences, Fudan University, Shanghai 200433, PR China.
authors.forename: Guohai
authors.initials: G
authors.lastname: Liang
authors.forename: Lifu
authors.initials: L
authors.lastname: Xiao
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.forename: Qian
authors.initials: Q
authors.lastname: Liu
authors.forename: Song
authors.initials: S
authors.lastname: Zhang
authors.forename: Fuyou
authors.initials: F
authors.lastname: Li
authors.forename: Jilie
authors.initials: J
authors.lastname: Kong
mesh_terms: D000469:Alkaline Phosphatase / Q000032:analysis* / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods*; D004355:Drug Stability; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D017895:Manganese Compounds / Q000737:chemistry; D009711:Nucleotides / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013194:Staining and Labeling
chemical_list: D058185:Magnetite Nanoparticles; D017895:Manganese Compounds; D009711:Nucleotides; D010087:Oxides; C027424:manganese oxide; D000469:Alkaline Phosphatase