| Polylactic acid（PLA）is a polyester polymer,which is widely used in the field of biomedicine due to its good biocompatibility,but it is rarely used in biochip technology;while maleic anhydride grafted polylactic acid（PLA-MA）has the advantages of more carboxyl groups and better thermal stability than PLA,and is regarded as a potential substrate material in the field of biochip analysis and detection.Quantum Dots（QDs）are a kind of fluorescent nanomaterials,which have the advantages of good fluorescence stability,high luminescence intensity and narrow emission spectrum,so they are ideal coding signal materials.The composite microspheres formed by the combination of polymers and QDs have the advantages of both,so they have great application prospects in the field of biological analysis and detection.Among them,liquid suspension biochip technology based on polymer fluorescently encoded microspheres has gradually become an important means of tumor marker immunodetection due to the advantages of multi-component,high-throughput,flexible detection,and accurate results.Therefore,this work mainly focuses on the construction and application of liquid suspension biochips with PLA-MA fluorescent microspheres as the carrier.（1）Construction of a liquid suspension chip based on PLA-MA microspheres encoded by Cd Se/Zn S QDs and its application in the immunodetection of tumor markersIn this work,we constructed a liquid suspension biochip for the first time using Cd Se/Zn S QDs-encoded PLA-MA microspheres as carriers.PLA-MA was synthesized by the functionalization modification reaction of maleic anhydride,and PLA-MA was synthesized with Cd Se/Zn S QDs by Shirasu Porous Glass（SPG）membrane emulsification combined with solvent evaporation method to prepare uniform particle size,uniform distribution of quantum dots and good fluorescence stability PLA-MA fluorescent microspheres.Then,the biological activity of PLA-MA fluorescent microspheres was verified by immunochromatography,which has the conditions for immunodetection of tumor markers.According to the characteristics of flow cytometry and Cd Se QDs and Cd Te QDs,a library containing 9 non-interfering and distinguishable PLA-MA encoded microspheres was established.Finally,Cd Te QDs were used as fluorescent reporter molecules,and PLA-MA fluorescent microspheres were used as carriers to construct a liquid suspension biochip to realize the immunodetection of carbohydrate antigens CA125,CA199,CA724 and carcinoembryonic antigen CEA.The detection limits were 1.60KU/L,0.92 KU/L,1.06 KU/L,and 0.138 ng/m L,respectively.The liquid-phase biological suspension chip shows good detection performance,high sensitivity and stable signal,and has a huge application prospect in the field of biomolecular analysis and detection.（2）Preparation and application of PLA-MA magnetic microspheres encoded by Cd Se/Zn S QDsIn this work,we constructed a liquid suspension biochip based on Cd Se/Zn S QDs-encoded PLA-MA magnetic microspheres.Fe3O4 nanoparticles with superparamagnetic properties were synthesized by a two-step method,and their application in immune reactions could suppress non-specific biological contamination and improve detection sensitivity.Then,by exploring the amount of quantum dots and Fe3O4 nanoparticles in the process of preparing microspheres by membrane emulsification method,PLA-MA microspheres with good magnetic and fluorescent properties were prepared.Using the magnetic PLA-MA fluorescent microspheres as the carrier of the liquid suspension biochip,the sensitive determination of alpha-fetoprotein AFP and carcinoembryonic antigen CEA was realized by sandwich immunoassay,with detection limits of1.15 ng/m L and 4.70 ng/m L,respectively.Compared with the liquid suspension biochip detection system based on non-magnetic microspheres,the detection system has the advantages of short time consumption,high efficiency and low loss,and has great advantages in the field of analysis and detection. |
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