Preparation And Performance Of Nanoparticle And Capillary Sensor Based On Fluorescence Analysis

In life activities,the concentration of H+,O2 and CO2 in blood,tissues and all kinds of cells is regarded as a very important physiological parameter,and its changes can usually reflect the basic state of respiration,metabolism and other functions.In recent years,researchers have further found that the concentration changes of H+,O2 and CO2 in cells are closely related to tumors and Alzheimer’s disease.Therefore,accurate monitoring of pH,O2 and CO2 is of great significance to the understanding of the mechanism of life activities and even the diagnosis of diseases.Fluorescence analysis method analyzes the changes of target parameters through the fluorescence intensity or lifetime fluctuation of specific fluorescent dyes or probes.Optical sensors based on fluorescence analysis method have the advantages of high sensitivity and fast response time,so they have been widely concerned in the measurement of physiological parameters.In this paper,in order to efficiently detect the dynamic changes of H+,V2 and CO2,two kinds of optical sensors based on fluorescence analysis are prepared,which mainly includes two parts:the first is the two-photon ratio fluorescence nanosensor to monitor the changes of intracellular pH,which can realize the ratio fluorescence imaging and real-time monitoring of intracellular pH and its fluctuations under the single photon and two-photon excitation modes.The second part is a multifunctional fluorescent capillary sensor that can simultaneously detect pH,O2 and CO2 fluctuations.It has good multi-parameter sensitivity,stability and reversibility under single wavelength excitation.The research content of this paper mainly includes:(1)A two-photon ratio fluorescence pH-sensitive nanosensor using conjugated polymer poly(9,9-dioctylfluorenyl,2,7-diyl)as matrix and fluorescein isothiocyanate(FITC)as a pH-sensitive probe was prepared by reprecipitation method.Transmission electron microscopy(TEM)and dynamic light scattering(DLS)analysis of the nanosensor showed that the particle size distribution of the nanosensor was uniform,about 150 nm.The ratio fluorescence of FITC and PFO exhibited high pH sensitivity in the pH range of 3～10 under single and two-photon excitation,and the pKa of single and two-photon excitation were 6.69 and 6.43,respectively.The nanosensor has high sensitivity,excellent stability,low cytotoxicity,good reversibility and two-photon excitation ability.Applied to HeLa cells,the sensor can successfully achieve ratio fluorescence imaging of intracellular pH fluctuations in single photon and two-photon excitation modes,thus monitoring intracellular pH fluctuations in real time.(2)A multifunctional fluorescent capillary sensor sensitive to the concentration of hydrogen ion,dissolved oxygen and carbon dioxide was prepared to monitor the concentration changes of three parameters in real time.The sensor used a single quartz capillary with an inner diameter of 2 mm as a carrier.The O2 sensitive fluorescent probe Ru(dpp);(PF6)2,pH and CO2 sensitive probe 8-hydroxypyrene-1,3,6-trisulfonic acid(HPTS)were fixed to the left,middle and right regions of the capillary wall through three films with different structures,respectively.SEM imaging showed that the sensor film was compact,and corresponding fluorescence signals of pH,O2 and CO2 sensitive probes could be collected in the left,middle and right parts of the capillary under the irradiation of a single excitation wavelength of 460 nm,realizing multi-parameter optical monitoring.The detection of each sensitive film on the inner wall of capillary showed that pH sensitivity was excellent,pKa=6.91.0-,sensitive films have high oxygen sensitivity and can be fitted by Stern-Volmer equation.The fluorescence intensity I0/I ratio has a good linear relationship with oxygen content.The quenching sensitivity of CO2 sensitive film is about 96%,showing high CO2 sensitivity.In addition,the capillary sensor has good specificity,storage stability and reversibility.The results show that the multifunctional capillary sensor has great application potential in real-time blood gas analysis and multi-parameter biological detection.