Study On The Method For On-line Determination Propofol Based On The Fiber-optic Sensing, The Molecular Imprinting Technique And Fluorescence Analysis

Propofol(2,6-diisopropylphenol)is a short-acting intravenous administered anaesthetic largely used for inauction and maintenance of anaesthesia.The rapid metabolisation of propofol in the body makes it necessary to have a continuous infusion.However, metabolic rates vary between individuals,making on-line monitoring of propofol desirable.Various methods have been reported for the quantitation ofpropofol in plasma or brood, high pressure liquid chromatography(HPLC)with ultraviolet(UV),fluorescence or MS electrochemical detection,gas chromatography(CJC)with atomic emission or mass spectrometric detection;Sample preparation prior to analysis by HPLC or GC requires either liquid-liquid or solid-phase extraction(SPE).But all of the assays are off-line analysis,and have disadvantages of sampling analysis.Therefore it is of significant importance to develop and establish an on-line monitoring technique or method for propofol for clinical safe validity control.A fiber-optic sensor is a device that is able to indicate continuously and reversibly the concentration of an analyte.The optical fiber sensors have certain advantages that include high sensitivity,lightweight,small size,immunity to electromagnetic interference,large bandwidth.The fiber-optic sensors break through the conventional spectral analysis pattern;they enable optical spectroscopy to be performed on sites inaccessible to conventional spectroscopy.The analysis of the sample can be carried out by guiding light through the fiber optic to the sample,thus avoiding the need to put the sample in a spectrometer and the disadvantages of sampling analysis.It is especially applicable for on-line monitoring of therapeutic drugs in biological samples.Fluorescence analysis method has an advantage of high sensitivity,strong selectivity and simpleness and is fit for drag analysis.With the rapid development of optical-fiber technology,fluorescence analysis technology shows more and more superiority in monitoring of therapeutic drugs. The fiber-optic techniques combining the fluorescence analysis are applied to improve the sensitivity of response for analytes.And its great potentialities on improving selectivity can be fully brought out by means of the molecular imprinting technique.Molecular imprinting is an emerging technique for preparing the polymeric materials possessing highly selective and affinitive properties.The technique involves complexation in a solution of a target molecule(template)with functional monomers through either covalent or noncovalent bonds followed by a polymerization reaction with an excess of cross-linkers.Removal of the templates leaves behind specific recognition sites that are complementary to the template in terms of its shape,size,and functionality in the polymer network.These cavities have highly selective molecular recognition to capture the target analyte.Recognition ability of some MIP to target molecule is comparable with crude molecular recognition system,such as antibody to antigen, enzyme to matrix.MIPs have several advantages over classical antibodies.For example they can be tailor-made for specific substances,the imprint molecule can be recovered after polymerization,and they are resistant to pH changes and organic solvents.In analytical separation science,The selectivity of MIPs has been exploited in several applications,such as chromatography,enantiomeric separations,solid-phase extraction and sensors.Our aim is to develop a quick and reliable method for on-line determination of propofol that would be free of interferences,either from other similar compounds or from blood components and approach for process monitoring of therapeutic drugs by means of hyphenating the Fiber-optic Sensor,the Molecular Imprinting Technique and Fluorescence analysis.In this thesis,Molecular imprinted polymer(MIP)against propofol was synthesized by using propofol as template molecule,methacrylic acid(MAA)as functional monomer and ethyleneglycoldimethacrylate(EDMA)as cross-linker and it had selective adsorptivity to propofol.Reaction condition such as ratio of monomer,propofol and cross linker was investigated.FT-IR,scan electron micrography and HPLC were used to characterize the MIP structure and surface features.According to batch binding experiments,propofol imprinted polymer exhibited higher affinity to propofol compared to nonimprinted polymer.Scatchard analysis indicated that there were two classes of recognition sites in propofol imprinted polymer and they had uniform affinity to propofol.Its dissociation constant K_d1and maximum apparent binding constant Q_max,1 of binding sites with high affinity was 0.4882 mol/L,23.47μmol/g respectively,while K_d2 and Q_max,2 of binding sites with low affinity was 5.731 mol/L,153.90μmol/g.Propofol bound to this polymer in 2 min and could be removed in 2 min,and the response rate is below the rate of metabolism of the anaesthetic.These results suggest suitability for use in an on-line propofol detection.The character of fluorescence and UV of propofol had been investigated,including influence of pH on fluorescence intensity of propofol and human plasma.Based on these, we developed fluorescence spectrometry method for the determination of concentration of propofol emulsion.The method is more simple and quick compared with the conventional methods,and what's more,it is suitable for quality control for emulsion.An Optical Fiber analysis instruments system based on Fluorescence signal for propofol determination had been developed.In the system,light from Xenon lamp passes through a collimated lens and the interference filter to achieve the correct light intensity and wavelength,then the light is guided through the fiber to the analytes,which can emit fluorescence in the flow-through cell.The fluorescence is guided back to the photomultiplier tube,converted to an electrical signal,amplified.The carrier steam is propelled with the pump;the sample is introduced into the carrier steam by means of the valve(Ⅴ)and the analyte quantity information is measured in the flow-through cell using the fiber-optic sensor.Based on the instruments system,an optical-fiber fluorescence measurement method which is used in on-line determination of propofol concentration had been established.The standard curve of propofol was linear with the concentration in the range 0.1～15μg/mL.The average recovery was 111.1%.The RSD of within-day and between-day were 4.8%and 6.6%.A quick and reliable method for on-line determination of propofol would be free of interferences,either from other similar compounds or from blood components,so the isolation or separation of lead compounds from natural resources followed by the bioassay guidance has played an important role.The final determination will be hindered while the analyte is retained together with other matrix compounds.However, conventional methods are often time-consuming and inefficient for thos procedure as a result of the poor affinity and selectivity of the analyte analysis.Materials that display molecular recognition capabilities are essential for biological samples.We investigated the potential of molecular imprinted materials used in the optic-fiber analytical system. The MIP obtained previous was developed to be the solid-phase extraction material, which allowed not only the other compounds present in the sample matrix to be removed but also the analyte to be preconcentrated.The results suggest its suitability use in an on-line propofol detection.