Iron oxide nanoparticles show peak at 261nm which is characteristic of it. If you could tell what exactly chemical composition of it, it would be more helpful to answer.

To record UV-Visible spectrum of Iron nanoparticles you can use powder sample or powder sample dissolved/suspended in some solvents or making thin film on some substrate.

these are magnetite having powder like appearence synthesized by coprecipitation method.I am qureious how to take threr uv ,as when they disperse in water ,they do not yield clear transparent black coloured solution.

Aiman, dried powder you first disperse in buffer or methanol (preferably) but not in water. Then go for sonication for 1 hr. You will get well dispersed solution which will remain stable only fraction of time (about 2-3 hrs). Take a spectrum scan of it against your corresponding blank. You will get peak at 261nm.

To get meaningful spectra (Absorbance not higher 2) you will have to dilute and to use thin optical cells. To minimize scattering influence in some instruments you can directly place the cells in front of the photomultiplier.

It is better to use powder sample in that case. If your UV-vis spectrometer has solid sample analysis attachment then load the powder sample holder and fill it to record the spectrum, otherwise you can spin coat that sample on glass/quartz plate and attached it with the sample holder.

What is the reason of their short time stability .How can their stability can be increased in liquid phase.How can we check the stability of magnetite nanoparticles.What other methods other than uv can be adopted.

Aiman, short term stability is mainly because of bare nanoparticles. These particles must be surface modified with some charged functional groups (to make them monodisperse by increasing the surface potential). Stability study can be done by studying the change in polydispersity index with time (by DLS).

Dispersion stability can be directly measured by observing the separation behaviour at gravity or in centrifugal field. Beside information on stable - unstable you get additional info on dispersion characteristics like flocculation, network formation etc.

see e.g.

Evaluation of particle interactions by in situ visualization of separation behaviour

http://www.sciencedirect.com/science/article/pii/S0927775712006917

As per me, the stability can be increased if you can use a capping agent and the stability study can basically be done by measuring zeta potential.

And about the UV spectra, after capping the iron nanoparticles say by using SDS microemulsiion, it would give a characteristic peak i.e the surface plasmon resonance at a particular wavelength.

Hello everyone,

As per my knowledge, IONPs once they come in nano form and having iron as a core component behave as insulators hence even if they show a peak at 261nm the line goes straight after that and there is no drop down in the absorbance.

Secondly, bare IONPs do not have aqueous colloidal stability hence it becomes mandatory to study the same in buffer, media or any other solvent system.

Thirdly, to evaluate the same DLS gives a hydrodynamic analysis which should not be relied on rather you can check the surface charge using Zeta potential after coating the bare IONPs at every step before and after coating. It will help you analyzing the solvent system for better stability also.

We have also done some similar type of studies in the recent publication:

http://www.ncbi.nlm.nih.gov/pubmed/24788586

Thanks to all of you ,can we use afm for the stability check ?

No you cannot use AFM for stability check

It will only hide you about the surface morphology and coating of the nanoparticles if any.

What kind of buffer can be used for the iron oxide nanoparticles?

Aiman, I dispersed my iron nanoparticles in PBS buffer of pH 7.2.

Why Deionized water (DI) is not used for dispersion of magnetite nanoparticles?

if we use methanol for dispersion of iron nanoparticles, then

what percentage of this methanol should be?

fariha kanwal ,

make different dilution of methanol , and according to your Uv result choose the best one