Magnetoluminescent Light Switches – Dual Modality in DNA Detection

Abstract

The synthesis and properties of two responsive magnetoluminescent iron oxide nanoparticles for dual detection of DNA by MRI and luminescence spectroscopy are presented. These magnetoluminescent agents consist of iron oxide nanoparticles conjugated with metallointercalators via a polyethylene glycol linker. Two metallointercalators were investigated: Ru(bpy′)(phen)(dppz), which turns on upon DNA intercalation, and Eu-DOTAm-Phen, which turns off. The characteristic light-switch responses of the metallointercalators are not affected by the iron oxide nanoparticles; upon binding to DNA the luminescence of the ruthenium complexes increases by ca. 20 fold, whereas that of the europium complex is > 95 % quenched. Additionally, the 17–20 nm magnetite cores, having permeable PEG coatings and stable dopamide anchors, render the two constructs efficient responsive contrast agents for MRI with unbound longitudinal and transverse relaxivities of 12.4 – 9.2 mM−1Fes−1 and 135 – 128 mM−1Fes−1, respectively. Intercalation of the metal complexes in DNA results in the formation of large clusters of nanoparticles with a resultant decrease of both r1 and r2 by 32 – 63 % and 24 – 38 %, respectively. The potential application of these responsive magnetoluminescent assemblies and their reversible catch-and-release properties for the purification of DNA is presented.

A review of responsive MRI contrast agents: 2005–2014

“…As another example, magnetite spheres with DNA intercalators can bind to DNA duplexes at 0.5 m M base pair concentration (Fig. ) . Although aggregation typically causes an increase in superparamagnetism of the system, the extreme aggregation of magnetite in this example reduced water accessibility and superparamagnetism, causing the T 2 * relaxation time constant of the system to increase.…”

“…The r 1 relaxivity (triangles) also decreases following aggregation. Reproduced with permission from Smolensky et al .…”

Preparation of DNA-immobilized magnetic particles and their utilization as an accumulative material of metal ions

“…Since Fe 3 O 4 is a paramagnetic material, 33 the composite material consisting of double-stranded DNA and Fe 3 O 4 particles can be simply collected by a magnet from an aqueous solution. 23 Therefore, we demonstrated the accumulation of heavy and rare-earth metal ions by the DNA-Fe 3 O 4 composite material and proposed the collection of metal ion-accumulated composite materials by a magnet. The utilization of the double-stranded DNA-immobilized Fe 3 O 4 particles as an environmental material has not been reported to the best of our knowledge.…”

“…Metal oxide particles have many functions, such as optical properties, 23,24 catalytic activities, 25 antimicrobial activities, 26 and the absorption properties. 27 Therefore, the metal oxide particles have been used as engineering materials, catalysts, absorbents, and biomedical materials.…”

Cationic Polyelectrolyte Mediated Synthesis of MnO2‐Based Core–Shell Structures as Activatable MRI Theranostic Platform for Tumor Cell Ablation

“…Due to its dependence on specific intracellular or extracellular biochemical stimuli, activatable MRI agents not only increase the detection limit but also report special tissue environment or metabolic activity in vivo . Nowadays, a number of activatable MRI probes have been developed to respond to different in vivo factors such as pH, temperature, and redox state. [5c,9] Among these various biological stimuli, change of redox state is particularly attractive due to its special role in pathophysiological process.…”