Preparing The Fiber-optic PH/PO2/PCO2Fluorosensors And Studying Their Application In Blood Gas Analysis

The accurate measurement of arterial blood oxygen partial pressure often plays an important role in the clinical assessment of gas exchange and metabolism in patients with respiratory conditions such as an acute exacerbation of chronic obstructive pulmonary disease and acute lung injury/adult respiratory distress syndrome. In general, arterial blood samples are usually drawn intermittently and analyzed by a conventional blood gas analyzer. The report might be delayed and there is a risk of blood loss and infection in the ICU.Considering these limitations, effort has been put on developing continuous inline blood gas monitoring systems for a critical care medicine to allow a timely clinical interference and avoiding infection from blood sampling.Continuous intravascular blood gas analysis system can monitor the real-time change of blood gas through a miniaturized probe inserted to arteries and allow for the timely clinical management. It would greatly improve the clinical monitoring abilities in intense care medicine.The study in this thesis include mainly:1) Fabricating another fiber-optic pH fluorosensor based on a proton-sensitive fluorescent dye AMPN and testing its performance in both in vitro and in vivo experiments;2) Fabricating a fiber-optic pH fluorosensor based on a proton-sensitive fluorescent dye APN and testing its performance in both in vitro and in vivo experiments;3) Fabricating a fiber-optic PCO2fluorosensor based on a proton-sensitive fluorescent dye HPTS and testing its performance in both in vitro and in vivo experiments;4) Fabricating a fiber-optic PO2fluorosensor and testing its performance by use of two separate systems based on fluorescence intensity or life time measurements, respectively;5) Fabricating a fiber-optic pH/P02dual-parameter fluorosensor and testing its performance. Part1Preparing a fiber-optic pH fluorosensor based on the dye AMPNObjectivesThe present study aims at preparing a more stable fiber optic pH sensor with good biocompatibility and suitable for intro-arterial blood pH monitoring.MethodsTo synthesize the indicator AMPN from4-Bromo-1,8-naphthalic anhydride, paraformaldehyde and so on. The quartz optical fiber was modified by silanization. Then, the indicator was bonded to the optical fiber followed by biocompatibility modification. The probe was attached to LED and spectrometer to assemble the real-time fluorescence monitoring system and then immersed to all kinds of buffer solutions or the collateral circulation system of the external carotid artery in rabbits with acidosis or alkalosis. The pH values were computed from the linear function established.ResultsThe sensor emitted stable fluorescence peak at518nm when excited at395nm. The fluorescence intensity decreased with increasing pH ranging from pH6.8to8.0, showing a negative linear relationship with pH values. The sensors showed stability in72hours, excellent reproducibility, reversibility and fast response time. Its shelf time was more than1year so far. The in vivo data showed that the fluorescent intensity was linear with pH value when the blood pH changed between7.1-7.6in rabbits. Linear regression and Bland-Altman analyses demonstrated that the sensor had an acceptable level of consistency with the conventional blood gas analyzer.ConclusionsThe fiber-optic sensor has a long stability, good reversibility, acceptable accuracy, a fast response and is suitable for long-term and continuous blood pH monitoring in animals with acidosis or alkalosis.Part2Preparing a fiber-optic pH fluorosensor based on the dye APN ObjectivesThe present study aims at preparing a fiber optic pH sensor with good biocompatibility and suitable for intro-arterial blood pH monitoring.MethodsTo synthesize the indicator APN from4-Bromo-1,8-naphthalic anhydride, Piperazin and so on. The quartz optical fiber was modified by silanization. Then, the indicator was bonded to the optical fiber followed by biocompatibility modification. Then, the indicator was bonded to the optical fiber followed coating by the co-polymer of2-methacryloyloxyethyl phosphorylcholine and n-butylmethacrylate. The probe was attached to LED and spectrometer to assemble the real-time fluorescence monitoring system and then immersed to all kinds of buffer solutions or the collateral circulation system of the external carotid artery in rabbits with acidosis or alkalosis. The pH values were computed from the linear function established.ResultsThe sensor emitted stable fluorescence peak at518nm when excited at395nm. The fluorescence intensity decreased with increasing pH ranging from pH6.0to8.0, showing a negative linear relationship with pH values. The sensors showed excellent reproducibility, reversibility and fast response time. Its shelf time was more than5months so far. The in vivo data showed that the fluorescent intensity was linear with pH value when the blood pH changed between7.1-7.6in rabbits. Linear regression and Bland-Altman analyses demonstrated that the sensor had an acceptable level of consistency with the conventional blood gas analyzer.ConclusionsThe fiber-optic sensor has an acceptable accuracy, a fast response, good reversibility and is suitable for long-term and continuous blood pH monitoring in animals with acidosis or alkalosis.Part3A fiber-optic PCO2fluorosensor prepared and testedObjectivesThe present study aims at preparing a fiber optic PC02sensor with good biocompatibility and suitable for intro-arterial blood gas monitoring.MethodsThe proton-sensitive fluorescent dye HPTS was incorporated in the hydrophobic sol-gel glass that is carbon dioxide-permeable, bution-impermeable. The probe was attached to LED and spectrometer to assemble the real-time fluorescence monitoring system and then immersed to the buffer solution bubbled by C02or the collateral circulation system of the external carotid artery in rabbits with respiratory acidosis or alkalosis. The PCO2values were computed from the linear function established.ResultsThe sensor emitted stable fluorescence peak at520nm when excited at480nm. The fluorescence intensity decreased with increasing PCO2ranging from14-150mmHg, showing a negative linear relationship with PCO2values. The sensors showed stability in25hours, excellent reproducibility, reversibility and fast response time. Its shelf time was more than3months so far. The in vivo data showed that the fluorescent intensity was linear with PCO2value when the blood PCO2changed between16-74mmHg in rabbits. Passing-Bablok regression and Bland-Altman analyses demonstrated that the sensor had an acceptable level of consistency with the conventional blood gas analyzer.ConclusionsThe fiber-optic sensor has a long stability, good reversibility, acceptable accuracy, a fast response and is suitable for long-term and continuous blood PCO2monitoring in animals with respiratory acidosis or alkalosis.Part4Preparing a fiber optic PO2fluorosensorObjectivesThe present study aims at preparing a P02-sensitive fiber optic fluorosensor and comparing their performance of fluoscence intensity and lifetime monitoring systems. MethodsThe PO2-sensitive indicator Ru(dpp)3(PF6)2was immobilized to the co-polymer of2-methacryloyloxyethyl phosphorylcholine and n-butylmethacrylate. The fabricated probe was attached to LED and spectrometer or Ocean Optics NeoFox phase measurement module. Exposed to different levels of PO2, the fluorescence intensity or lifetime of the sensor was recorded and analyzed. The stability was compared when they were exposed to the same PO2level.ResultsThe sensor emitted stable fluorescence peak at615nm when excited at460nm. Both the fluorescence intensity and life time decreased with increasing PO2ranging from0-150mmHg, showing a negative linear relationship with P02values. The fluorescent intensity was demonstrated a better stability in25hours than the fluorescent life time.ConclusionsThe PO2-sensitive fluorosensor had a better stability and accuracy when determining the fluorescent intensity as sensitive signal than the fluorescent life time.Part5Preparing the pH/PO2dual-parameter fluorosensorObjectivesThe present study aims at preparing a pH/PO2dual-parameter fluorosensor, making the two signals transmitted through a single optic fiber and miniaturing the multi-parameter sensor.MethodsThe PO2-sensitive filming was coated to the upside of the pH probe. The fluorescent intensity at518nm and615nm was recorded separately when the fabricated dual-parameter probe was excited at400nm. Its selectivity and accuracy were analyzed when the sensor was exposed to the solutions of pH6or8or bubbled by100%N2or O2.ResultsThe sensor emitted green and red dual-color fluorescence simultaneously when excited at400nm. Both the two fluorescence intensity peaks at518nm and615nm changed separately with different pH or PO2values and weren’t interfered each other.ConclusionsThe pH/PO2dual-parameter fluorosensor can determine accurately both of pH and PO2simultaneously.