From my opinion this will be possible. The acid can bound to the surface.
the metho of choice is FT-IR (ATR prism).
I guess the the used ZnO is head treated or modified with acetic acid. The best results will be obtained with freshly prepared unmodified ZnO.
you find the simple procedure and the surface analysis by IR and Raman within our publications ( note that a clear solution of ZnCl2 lead to the smallest particles). 2 example articles
Article Synthesis and testing of ZnO nanoparticles for photo-initiat...
Article ZnO nanoparticles as polymerisation Photo-Initiator: levulin...
Zinc Oxide is an interesting material due to its wide spectrum applicability. I can tell ZnO nanoparticles can be coated with another material.The answer to your question is totally dependent on the structure of the material especially if it is spherical superstructure of upto 4000nm. it is seen that when small spherical nanoparticles aggregate together they form a superstructure whose surface becomes Zn+ and due to uv irradiattion it becomes Zn2+ leading to a increase in the absorbance in ZnO excitoonic peaks along with it make the materials surface positively charged. Maybe due to this surface charge the drug has got incorporated with the ZnO. i can tell you to change the ZnO structture, it might work let me know.
you can look into my article Article Influence of the various synthesis methods on the ZnO nanopa...
Thanks Michael sir and Raunak sir for your valuable suggestions. My nanoparticles are aggregated and the average size is around 500 nm. I tried to coat with PEG-6000 first so that drug can be incorporated inside the polymer chains which didn't work. Now i am planning to use BSA for coating of nanoparticle and then drug loading. Please let me know if you have any suggestions regarding this.
Thanks Raunak sir for your input. Can you please elaborate on your answer. Should i coat my nanoparticle with sodium alginate and then try to cross link it with indomethacin?