The invention provides a vehicle for colorimetric assay which expands upon {HEAD ~ contact} with {TAIL ~ biological fluids} 
with
The invention provides a vehicle for colorimetric assay which expands upon { HEAD ~ contact } with { TAIL ~ biological fluids }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL