The hydrogel matrix comprises about 3 to {TAIL ~ about 150 mM} of {HEAD ~ polar amino acids} 
The hydrogel matrix comprises about 3 to { TAIL ~ about 150 mM } of { HEAD ~ polar amino acids }
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD