I have thus far been unable to get DLS characterizations of some ultrasmall iron oxide nanoparticles that I purchased commercially and I believe it is due to high rates of aggregration, especially as I have had a hard time getting a the nanoparticles fully solubilizzed in solution (water, PBS, DMSO). I'm thinking that maybe adding a surfactant could be effective at reducing aggregation just for the purpose of hydrodynamic diameter and zetapotential readings. Any suggestions for best surfactant options?
Can you provide a link that describes the particles you purchased?
If they are dry, you will have a very hard time getting them to full disperse into a liquid. This is generally true for any nanoparticles in dry form unless they have a suitably modified surface.
I would like to know why you want to know the particle size and zeta potential, and what your application is for the particles. It may be that these two characterization tools are not appropriate for your need.
Surfactants are compounds that can reduce surface tension between two substances. In the context of metal nanoparticles, surfactants are often used to stabilize and prevent aggregation of nanoparticles in solution. Aggregation refers to the clumping together of nanoparticles, which can negatively affect their properties and hinder their applications.
When selecting surfactants for preventing aggregation, several factors should be considered, including the nature of the metal nanoparticles, the desired stability, and the specific application requirements. Here are some commonly used surfactants for stabilizing metal nanoparticles:
Dorian Foster
Based on your research interests, you would like to prepare and study a dispersion of iron nanoparticles to create a contrast agent in magnetic resonance imaging. To do this, you need to use surfactants that are compatible with the human body. Try dextran H(C₆H₁₀O₅)nOH or the closely related mannitol (C6H14O4).
Dorian Foster The stages in making a stable dispersion (as well-known by paints and ceramic experts) from a powder are:
- Wetting
- Separation
- Stabilization
If your iron oxide (powder) particles do not wet in the liquid you're intending them to be dispersed in then this is the function of a surfactant (wetting agent). If your particles wet then you don't need a surfactant generally. Separation is achieved with input of energy, typically ultrasound in the wet. If the particles aggregate or agglomerate after separation then a stabilizer (charge/electrostatic or steric) is needed. IMHO, this is where your issues lie. I'd try sonicating in a 0.05wt% sodium hexametaphosphate solution as the phosphates are classic inorganic oxide stabilizers. Take a look at the following webinar (free registration required) for more details:
An acronym approach to laser diffraction method development: https://www.malvernpanalytical.com/en/learn/events-and-training/webinars/W190815PST
I agree with John Francis Miller . If your particles are in the dry form it's going to be very difficult to disperse them. Try measuring the specific surface area of the powder by BET. It should be greater than 60 m2/cm3 for the particles to be considered less than 100 nm. Also see plenty of discussions on Research Gate on this topic.
2 quotes from those much greater than I:
'I think dry nanotechnology is probably a dead-end' Rudy Rucker Transhumanity Magazine (August 2002)
‘If the particles are agglomerated and sub-micron it may be impossible to adequately disperse the particle… ‘The energy barrier to redispersion is greater if the particles have been dried. Therefore, the primary particles must remain dispersed in water...’ J H Adair, E. Suvaci, J Sindel, “Surface and Colloid Chemistry” Encyclopedia of materials: Science and Technology pp 8996 - 9006 Elsevier Science Ltd. 2001 ISBN 0-08-0431526
See also a recent question:
https://www.researchgate.net/post/Which_solvents_could_contribute_to_a_realistic_measurement_of_the_hydrodynamic_diameter_via_dynamic_light_scattering_DLS
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Materials
- Carbon Materials
- Graphite
- Graphene