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Two or more metal ions along with [beta]-amyloid were incubated over a solid template prepared by immobilizing A[beta]42 oligomers to explore the nature of codeposition of different metals. The results reveal the significant role of multiple metal ions in interactions with Alzheimer's A[beta] or its aggregates.

Recently discovered evidences suggest that precipitation of Alzheimer's β-amyloid (Aβ) peptide and the toxicity in Alzheimer's disease (AD) are caused by abnormal interactions with neocortical metal ions, especially Zn2+, Cu2+, and Fe3+. While many studies had focused on the role of a "single" metal ion and its interaction with Aβ peptides, such studies involving "multiple" metal ions have hardly been explored. Here, to explore the nature of codeposition of different metals, two or more metal ions along with Aβ were incubated over a solid template prepared by immobilizing Aβ42 oligomers. The influence of Zn2+, Cu2+, and Fe3+ on Aβ aggregation was investigated by two approaches: co-incubation and sequential addition. Our results using ex situ AFM, ThT-induced fluorescence, and FTIR spectroscopy indicated that the co-incubation of Cu2+, Zn2+, and Fe3+ significantly altered the morphology of aggregates. A concentration dependence study with mixed metal ions suggested that Zn2+ was required at much lower concentrations than Cu2+ to yield nonfibrillar amorphous Aβ deposits. In addition, sequential addition of Zn2+ or Cu2+ on fibrillar aggregates formed by Fe3+ demonstrated that Zn2+ and Cu2+ could possibly change the conformation of the aggregates induced by Fe3+. Our findings elucidate the coexistence of multiple metal ions through their interactions with Aβ peptides or its aggregates. [ABSTRACT FROM AUTHOR]

Molecular imaging has gained utmost importance in the recent past in early diagnosis of diseases. In comparison to other imaging modalities, magnetic resonance imaging (MRI) has proven to extend its abilities not only for its usage of non-ionizing radiation but also for the high spatial resolution in soft tissues. A major limitation faced by MRI is the sensitivity in detecting diseased conditions until a certain stage. At present, this limitation is overcome with the use of contrast agents that show potential in altering the T1 and T2 relaxation times of the hydrogen protons. This modulation to the relaxation times leads to better contrast differences based on the type of contrast agent and the pulse sequence being engaged for acquiring images. Water molecules, as the major contributor of hydrogen protons, are proven to interact with such contrast agents. Major drawbacks noted with the marketed MRI contrast agents are their toxicity and renal clearance. To conquer these issues, magnetic nanomaterials are being researched for their abilities to match the contrast enhancement offered by traditional agents reducing their drawbacks. Furthermore, comparative diagnosis with both T1 and T2 contrast at the same time has also interested investigators. To achieve this, twin mode T1 and T2 weighted contrast agents are developed utilizing the remarkable properties extended by magnetic nanoplatforms. As a step forward, multimodal imaging agents are also being engineered based on these magnetic nanoplatforms that will generate cross-verified diagnoses using multiple imaging modalities with a unique imaging agent. This review starts by introducing the basics of MRI with major focus on the typical interactions of water molecules with a variety of magnetic nanomaterials. The review also concentrates on the clinical needs and nanomaterials available for twin T1 and T2 contrast with a minor introduction to multimodal imaging agents. In conclusion, the advent of MRI with the advantages offered by magnetic nanomaterials is summarized, leading to insights for future developments.