ratiometric techniques can be used to determine activity levels of reactive oxidation species in a target area to indicate inflammatory responses and / or infection . target areas may be a tissue surface , a wound , and / or a body cavity . a ros - sensitive bioluminescent agent and ros - insensitive fluorescent reference dye are conjugated to surfaces , biocompatible particles , or polymer carriers . the compounds may be constituted as a spray , solution for injection , a wound dressing , medical implants , and / or medical device . the bioluminescent compound and reference fluorescent intensity ratios can be calculated to reflect the extent of localized ros activities .