Controlled Synthesis And Tumor Marker Detection Of Magnetic SERS Encoded Microspheres

With the rapid development of modern biomedicine,in the clinical diagnosis and other fields,it is very important to perform rapid and high sensitive quantitative detection of multi-component biomolecules in samples such as tumor markers.Although traditional flat microarray biochips have the advantage of multi-component target biomolecule analysis,there are still inadequacies in the accuracy of the detection results,the rate of immune binding kinetics,the rate of decoding analysis,and flexibility.In recent years,biochips with encoded microspheres have shown great benefits as carriers.Microspheres,which can be suspended and dispersed in the liquid sample to be detected,have faster kinetic binding rate and separation and washing steps,and the production technology of encoded microspheres is relatively simple,the detection results of encoded microspheres have better repeatability and higher sensitivity.Among many encoded signals,spectral signal encodings such as fluorescence and reflection are the most widely studied due to their flexible operation and easy decoding.Compared with organic fluorescent signals,surface-enhanced Raman spectroscopy?SERS?signals have great advantages: Raman spectral peaks have extremely narrow half-widths?? 1 nm?and wide range of encoding;Raman spectra have fingerprints features of probe molecules.There are many types of organic probe molecules,and they are able to be combined with Raman peak strength to carry out joint coding with large coding capacity.The SERS signals have very high sensitivity and strong detection ability.So SERS is widely used in the field of biomolecule detection.At present,coding microspheres usually use monodisperse polymer microspheres or polymer precursor spherical droplets as templates,and the swelling method,sol-gel method,layer-by-layer assembly method or emulsion polymerization are used to introduce coding elements into the microspheres to synthesis microsphere coding chip.However,the random distribution of Raman coded particles will result in poor reproducibility of Raman signals in different regions for Raman coding.To address this problem,this paper proposes to use monodisperse magnetic coded particles as an assembly unit and use optical microfluidics to prepare Raman-encoded particle assembly microspheres with the periodic structure as biochips,and the rapid detection of multi-component biomolecules is achieved by combining with the highly sensitive properties of Raman probes in the meantime.The specific research contents are as follows:1.Construction of monodisperse magnetically encoded nanoparticles and SERS probe particles.Using Fe₃O₄ @ SiO₂ microspheres as magnetic cores,a layer of silver nanoparticles was deposited as the SERS substrate by controlling the reaction conditions,and organic compounds containing thiol groups were selected as Raman probe molecules.Four suitable organic molecules which are TFTP,35-DTP,4-BTP,and MMTAA were chosen by Raman characterization and were used as coding signal molecules and Raman quantitative detection signal molecules respectively.Regulating the type and number of probe molecules to encode by studying the adsorption kinetics of probe molecules on the surface of the silver shell.Then 19 different types of magnetic Raman-encoded nanoparticles are realized via coating probe molecules with silica shells.On that basis,the magnetic SERS microspheres modified with MMTAA labeled molecules were used as precursors,and the hollow Raman probe particles were developed by removing the magnetic core.And then the oxalic acid was chosen as an etchant to prepare a sandwich hollow Raman probe nanoparticles.The ratio of this type of probe to the silver nanoparticle probe increases the Raman signal by tenfold.2.Synthesis of magnetic Raman-encoded particle assembly microspheres based on optical microfluidics.Monodisperse magnetically coded particles as assembly units and polymer monomer PEG-DA as curing agents,droplets containing Raman-encoded nanoparticles and polymer monomers are formed by a photomicrofluidic device,and the photoemission curing is used to achieve synthesis of magnetic raman-encoded particle assembly microspheres.By adjusting the flow rate ratio,the concentration of magnetically coded microspheres,the amount of PEG-DA solvent,the periodic structure of Raman-encoded particles in the microspheres is optimized to synthesize high-quality and adjustable magnetic Raman Encodes particle assembly microspheres.CEA and AFP were chosen as the target biomolecules to modify the surface of the Raman-encoded microspheres with antibodies.These were employed in combination with the Raman probes of the sandwich structure described above to investigate the detection performance of the target biomolecules.The results show that the assembly carrier combined with the above probe particles can achieve trace detection of CEA and AFP,and the tumor marker concentration in the range of 0.5 pg/m L to 0.1 ng/m L has a good linearity with the Raman signal Relationship,the lowest detection limit can reach the order of 10 fg/m L.