Study On LiOH/Non-woven Composites For The Detection Of Helicobacter Pylori

¹⁴C-urea breath test(¹⁴C-UBT)is one of the most commonly used clinical methods to detect helicobacter pylori infection.The absorption of CO₂ exhaled from the body by alkaline substances in the ¹⁴C-UBT gas collection card is a crucial part of the test.However,the alkaline substances inside the product are unevenly distributed and attach a large number to the interior of the substrate,while the air flow of exhaled gas only skims over the surface.At the same time,the radioactivity of ¹⁴C is extremely weak,and the internal radiation signal of the matrix material is easily blocked.This leads to inefficient utilization and absorption of alkaline substances.Moreover,the uneven distribution of the indicator makes the color shades vary and the color change time unstable,which is difficult to effectively show the synergistic effect between absorption zone and indicator area.This greatly affects the accuracy of the test.In order to solve this problem,LiOH was used as the alkaline substance,polypropylene（PP）non-woven fabric as the matrix material,tropaelin as the indicator,the interfacial tension between solution and substrate was regulated by the nonionic surfactant AEO-9.LiOH/non-woven composites（absorption zone）and tropaelin/LiOH/non-woven composites（indicator zone）were prepared by solution spraying and dropwise infiltration processes respectively.The specific research contents are as follows:1.Preparation and research of LiOH/non-woven composites.LiOH/non-woven composites were prepared by spraying LiOH aqueous solution containing surfactant AEO-9on the surface of PP non-woven fabrics and vacuum drying.The effects of different surfactant concentration,LiOH concentration,spraying time on the loading structure and CO₂adsorption performance of composites were mainly explored.The composite materials were compared with domestic commercial products,and the CO₂ adsorption kinetics of the composites were studied.The results show that lower AEO-9 concentration and higher concentration of LiOH solution are more likely to form surface load structure.With the extension of spraying time,the load of the composite material increase,and the permeability decrease,so the spraying conditions with higher permeability should be selected on the premise of meeting load.When the AEO-9 concentration is 0.2 g/L,the LiOH concentration is 100 g/L,and the spraying time is 7 s,the single-sided loading of LiOH reaches 102.8 mg,which meets the requirements of single-sided loading exceeding 100 mg.The CO₂ adsorption capacity is 2.39 mg/cm²,the adsorption efficiency reaches 49.9%,and the adsorption equilibrium time is about 180 s,which is significantly better than commercial products.At the same time,the adsorption process of CO₂ by composite materials are more in line with the Avrami fractional model,and the CO₂ adsorption process is controlled by the rate of various adsorption steps.2.Preparation and research of tropaelin/LiOH/non-woven composite materials.The composites were prepared by adding the solution dropwise to the center of the outer surface of the non-woven fabric to spread and penetrated.The optimal drying conditions were explored,and the effects of indicator concentration,surfactant concentration and LiOH concentration on the structure and properties of the composites were explored.The results show that the surface color distribution of composite materials with a moisture content of about 26%is relatively uniform when the composite materials are prepared at 55℃and dried under atmospheric pressure in air oven for 20 minutes,which meets the requirements of color change time of 2-3 min and is close to the time required for adsorption equilibrium in the absorption zone.The higher concentration of tropaelin is,the darker of the color of composite is.The color change is obvious after CO₂ adsorption,but it has less effect on the discoloration time.When the concentration of AEO-9 is 2.0 g/L,the solution can be spread well on the surface of the substrate,but the stability of the color change time may be affected when the concentration of AEO-9 is too high.When the LiOH concentration is 40 g/L,the surface distribution of the composite is relatively uniform,and the discoloration is relatively complete.The average discoloration time is 150 s,which is similar to the commercial product discoloration time,but the stability of the composite material discoloration time is better.And indicator zone has a good synergistic effect with the absorption region.