25000
We report the peptide - directed preparation and X - ray structural study of biofunctionalized Au nanoparticles ( NPs ) deposited on Ti surfaces .
 Chemical: Au; Chemical: Ti
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: Au, Ti 
Answer:
 Chemical: Au; Chemical: Ti