| Recent years have witnessed the trend of the higher mortalityof cancer,and finding rapid,quantitative and sensitive methods for the detection of tumor markers is of importance in early discovery and treatment for major diseases.As the product of protein hydrolysis in human biochemical system,peptides play an important role in the digestion and absorption of amino acids.When cells exhibit cancerous changes,cancer cells show great difference with normal cells in the process of metabolism,especially in the process of peptides generation.Therefore,by detecting the level of tumor-related peptides,people could discover cancerous cells and achieve early warning of cancers as well.The nucleic acid cycle amplification method,represented by hybridization chain reaction technology,has attracted much attention because of its simple reaction conditions and high signal amplification efficiency.Microfluidic paper based analytical devices,using ordinary chromatography paper as the base material,show great advantages in low cost,simple manufacture and good biocompatibility.By introducing the effective nucleic acid cycle photoelectric signal amplification system into microfluidic paper based analytical devices,the construction of sensitive biosensor for detecting tumor-ralated peptides is of great significance for reducing the detection cost and improving the detection sensitivity.Our main research is as follows:1.A preliminary study of nucleic acid cycle amplification method was carried out.And a simple and rapid method for detecting tumor-related peptides was designed,which combined the recognition of aptamers,the quenching effect of graphene oxide and the amplification strategy of nucleic acids into one experimental system.Aptamers here were not only able to recognize target peptides specifically,but also able to trigger the hybridization chain reactions between hairpin probes.Benefited from the adsorption and enrichment effect of graphene oxide,the reaction time of hybridization chain reaction was greatly shortened,and the quenching effect of graphene oxide reduced the background signal,thus greatly improving the sensitivity of the detection system.2.A high efficiency nucleic acid cycle amplification system combined with low cost microfluidic paper based analytical devices was used to construct a paper based biosensor for the sensitive detection of tumor-related peptides.The presence of target peptides caused the separation of initiation sequence from the designed aptamers.Thus,the hybridization chain reaction between the two hairpin probes could form long chain DNAs on the sensing surface,which successfully transformed the detection of target products into the quantification of the long chain DNAs after effective amplification.When a large number of electrochemiluminescence probes were embedded into long chain DNAs,the gained signals indirectly established a quantitative relationship with the content of target peptides,so as to achieve the sensitive detection of target peptides.3.Based on the combination of microfluidic paper based analytical devices and DNA strand replacement of nucleic acid cycle amplification technology,an electrochemical aptamer sensor for simultaneous detection of two targets was designed and constructed.The electrochemical labeling of metal ions and Ru complex electronic wires were combined on microfluidic paper based analytical devices as well.The target specific recognition was based on the fact that the affinity between the target and the aptamer was greater than that between the aptamer and its complementary sequence,the signal conversion and amplification was achieved by the large loading of Au/bovine serum albumin nanoparticles for electrochemical labels of two metal ions and their respective specific electrochemical peaks.And the sensitivity of the detection system benifited greatly from the introduction of the Ru complex into the detection system by the formation of electronic wires for reducing the resistance effect of the DNA skeleton to the electron transfer. |
PDF Full Text Request