9959
Utilizing the NIR optical absorbance of NGO , the cellular uptake of NGO - PEG - PEI is shown to be enhanced under a low power NIR laser irradiation , owing to the mild photothermal heating that increases the cell membrane permeability without significantly damaging cells .
 Chemical: PEG; Chemical: PEI
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: PEG; Chemical: PEI