If you wish to work on nanoparticle synthesis then you need to find a way to synthesize NPs by physical, chemical or biological way.
If you want to NPs synthesis by biological entities then search plant with medicinal property and not reported yet.
Green or eco-friendly synthesis of silver, gold, platinum, molibdenum etc.. NPs synthesis is possible and after that try to apply in biological or chemical applications.
You can read research articles on above mentioned topic in my RG acount.
You may first need to decide weather this study will be self funded...OR you have funding from some agency.
After this you may need an approval letter from a supervisor from a University (Europe) under whom you wish to persue the study.
Then if you sort this, you may need to additionally considering fulfilling all the qualification criteria for that university (like english test...etc)
Followed by this Visa... (University may provide you with visa support letter..etc)