into account the shrinkage of the monolith during curing and drying the fast responding monoliths have an approximate cytochrome c concentration of 2 2 3 u00d7 0 092 0 98 mm or 2 2 3 u00d7 1 1 11 71 mg ml these concentrations are near to but not the maximum concentration of cytochrome c allowable for a fast responding monolith with this in mind the maximum allowable concentrations of cytochrome c in fast responding thin films and monoliths trace gas sensors are both close to 2 mm or approximately 25 mg ml in the final xerogel state a key benefit of diluting cytochrome c concentration is that in going from high concentration to low concentration the protein goes to a slightly more unfolded state also referred to in the literature as the molten globule state in the molten globule state one of the axial ligands of the porphyrin is further removed on average from the iron center probably resulting in an opening of the protein up for more easy access to nitric oxide binding it is observed that the same process parameters which yield a more folded protein also decrease the responsivity of the sensor increasing concentration of protein to 5 u00d7 and 10 u00d7 concentration results in a more folded state of the protein and at the same time it is observed that the rate of response to nitric oxide decreases in.