Hi Amr, I dont have any stats to work with so tried comparing the slopes of the 2 curves, it seems that the slope for the coated is less by 5.5 degrees, suggesting a wider distribution in size post coating. If the coating was uniform, I would expect a distribution that is similar to pre-coating.

Not sure how to interpret how off 5% is, I then compared your compared your spectral data to that published by El-Nahhal et al, 2015, -figure 6 =, and your data looks much better.

If you need to determine accurately the efficiency of coating, you will need to use X-ray photoelectron spectroscopy (XPS). The methods and calculations are referenced here: Article Engineering safer-by-design silica-coated ZnO nanorods with ...

If you do not have access to XPS, I recommend you contact the final author in this publication. Most chemists are open to collaborations.

Dear Dr. Amr Mahmoud ,

I suggest you to have a look at the following papers:

-Engineering safer-by-design silica-coated ZnO nanorods with reduced DNA damage potential

Georgios A. Sotiriou, Christa Watson, Kimberly M. Murdaugh, Thomas H. Darrah, Georgios Pyrgiotakis, Alison Elder, Joseph D. Brain and Philip Demokritou

Environmental Science: Nano, 2 (2014)

Avalable at: https://pubs.rsc.org/en/content/articlelanding/2014/en/c3en00062a/unauth#!divAbstract

-Reducing ZnO nanoparticles toxicity through silica coating

Sing LingChia, David TaiLeong

Heliyon, 2 (10) 2016

Available at: https://www.sciencedirect.com/science/article/pii/S2405844016307514

Good work and best regards, Pierluigi Traverso

I checked them already before asking and I didn't get how XPS is used in the first paper to say that 95% of ZnO is coated with Silica

Dear all, the attached file covers the preparation and characterization of NPs in question. Generally, the différences in x-ray reflexions and microscopy images are used to get the dimensions of the different phases. My Regards

Why do we advocate green synthesis of nano particles of nutrients , even green composites ....these days

if your nanorods are very uniform, you might try a quick and dirty approach. you can check the distribution in size before and after coating using a spectrophotometer

Lora Benoit this the comparison between them

Hi Amr, I dont have any stats to work with so tried comparing the slopes of the 2 curves, it seems that the slope for the coated is less by 5.5 degrees, suggesting a wider distribution in size post coating. If the coating was uniform, I would expect a distribution that is similar to pre-coating.

Not sure how to interpret how off 5% is, I then compared your compared your spectral data to that published by El-Nahhal et al, 2015, -figure 6 =, and your data looks much better.

If you need to determine accurately the efficiency of coating, you will need to use X-ray photoelectron spectroscopy (XPS). The methods and calculations are referenced here: Article Engineering safer-by-design silica-coated ZnO nanorods with ...

If you do not have access to XPS, I recommend you contact the final author in this publication. Most chemists are open to collaborations.

try using a spectrophotometer to measure the coating of ZnO nanoparticles with Silica

Hi Amr ,

coating effciency can easily be measured by MALS (multi angle light scattering).

One may consider to separate the sample before an analysis by Field Flow Fractionation (FFF) to split it into 3 major fractions: (1). ZnO, (2). Silica, (3). Coated NPs. Depending on the grade of the increadiants (in terms of size), I would expect 2 sharp peaks of (1) and (2) and a brought peak of (3) this one will contain all differently coated NPs. For quantitative Analysis you devide the Molecular Mass signal of Peak (3) by the Mass of ZnO. The result is the coating efficiancy. If you hyphenate the measurement by an dRI or UV concentation detector, you will also get the precise concentration for each coated species within Peak (3).

This method is well known since several years. Unfortunately you wiill need expensive hardware like HPLC+UV+FFF+MALS+dRI. I worked several years for Wy*** Technology. This is a standard analysis, that drives you quantitativly and qualitatively forward.

Good Luck!

Hello Amr Mahmoud ,

If you are coating it on Silica wafer then it can be easily measured in Ellipsometer. This is the instrument which can measure film thickness on the surfaces. Note that you have to clean the silica wafer before you are going to coat it with any layer. (Common practice of cleaning these wafers is by using Piranha solution. I hope this helps. Good luck.

ZnO NPs concentration can be controlled prior to coating, during preparation.

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Hi Amr Mahmoud - You might also look into dynamic / electrophoretic light scattering to see a size and charge change of your nanoparticles. This article shows some data where the hydrodynamic size of the coated ZnO was signficantly larger than uncoated, and also a difference in effective charge was seen: Article Surface modification of zinc oxide nanoparticles with amorph...