541
Altogether , we demonstrated that the microneedle arrays can be fabricated through a simple single - step process and needles were mechanically strong to penetrate skin , increasing the permeability of encapsulated drug through skin .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None