Superparamagnetic iron oxide nanoparticles have received great attention due to their applications as contrast agents for magnetic resonance imaging (MRI). This feature article briefly introduces the concepts of MRI and MRI contrast agents, and then mainly discusses the synthesis, surface modification, surface functionalization, colloidal stability and biocompatibility of iron oxide particles, followed by their MRI applications.

Superparamagnetic iron oxide nanoparticles: from preparations to in vivo MRI applications

Synthesis and physical characterization of magnetite nanoparticles for biomedical applications

Co-precipitation in aqueous solution synthesis of magnetite nanoparticles using iron(III) salts as precursors

Static magnetization and Mossbauer measurements on ultra-fine crystallites (≈ 65 A) of γ-Fe2O3 show them to be superparamagnetic at 296 °K with an average relaxation time of 2 × 10−9 s. The particle size distribution is derived from the magnetization curve which exhibits no hysteresis, and independently from the temperature variation of the ratio of remanence to saturation magnetization. Mossbauer spectra at 5 °K in an applied field of up to 50 kOe show a cation distribution of 1:(1.71 ± 0.05) for A and B sites, and a non-collinear spin arrangement. The low value of the magnetization, 59 e.m.u./g at 4.2 °K for 1/H = 0, is explained by assuming that the spins of cations, which lie in the surface layer, make random angles between 0 and 90° with the direction of the net moment. Allowance is also made for water adsorbed onto the particle surface. When a field is applied to the absorber at 296 °K the spectrum changes from a broad single peak into two broadened hyperfine patterns from A and B sites which are explained by the magnetic polarization and range of ordering temperature of the particle distribution.

Superparamagnetic γ-Fe2O3

The temperature stability of acicular maghemite (γ-Fe2O3) was studied between 20°C and 600°C by x-ray diffraction and magnetic measurements. Synthetic monodomain maghemite was found to be stable with respect to hematite (α-Fe2O3) at temperatures as high as 500°C, inverting to α-Fe2O3 between 510-660°C. However, a complete inversion of the γ to α form for the sample was not achieved even at 660°C, the final product was a two-phase mixture, with 65% of the original γ-Fe2O3 unchanged. Two conclusions are made: (a) the absence of maghemite in a natural sample cannot be proven if heating has been restricted to moderate temperatures (300°-400°C) and (b) the true Curie point of pure maghemite is close to 645°C.

High temperature stability of maghemite (γ-Fe2O3)

The oxidation of magnetite and related spinels. Constitution of gamma ferric oxide

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

A. J. E. Welch

Author Tools

Chat about Author

Papers

The oxidation of magnetite and related spinels. Constitution of gamma ferric oxide