ИСТИНА

Exhaled breath condensate (EBC) is a noninvasively collected (i. e. harmless to skin, blood vessels, etc.) fluid of a versatile content (nitrogen oxides, salts, low molecular metabolites such as lactate, glucose; peptides). As multicomponent sample, EBC is a promising object for medical diagnostics. The condensate is usually sampled by cooling of exhaled aerosol at near-zero temperatures and below (EcoScreen, RTube, and others). Since relative humidity of the aerosol can reach 95%, the resulting sample is diluted by about 1000 times with condensed water vapor. In this work, we proposed a collection of EBC based on the condensation of exhaled aerosol during an intense collision of droplets in turbulent flow at ambient temperature. This approach does not require forced cooling and thus is expected to reduce dilution with condensed water vapor. Using cyclone separator scheme, a 3D-printed plastic cell was designed to collect condensate in the Eppendorf microtube at the outlet. EBC was collected from healthy volunteers for 10-30 minutes during the exhalation into the designed cell. Electroanalysis of metabolites levels (glucose, lactate) was performed in amperometric power generation mode of Prussian blue based electrochemical biosensors. The content of glucose in the samples varies in the range from 20 to 150 µM, lactate content – from 40 to 250 µM. Compared to blood, collected condensate shows a dilution about 100 times. Total ionic strength of EBC was assessed by electrochemical impedance spectroscopy (EIS). Samples for EIS were collected while fasting and 2-4 hours after meal. Relative to physiological saline, ionic strength of the samples are about 100 times lower which is consistent with the results of amperometric detection of glucose and lactate. Thus, in contrast to cooling, the proposed approach decreases dilution of the EBC by condensed water vapor by at least 10 times.