| In recent years,with the increasing public awareness of environmental protection and an in-depth understanding of the relationship between the environment and human health,the health effects of the population and ecosystem health problems caused by environmental pollution have attracted widespread attention from many scholars.In order to ensure human health,on the one hand,measures such as source prevention and comprehensive treatment of environmental pollution are taken;on the other hand,early detection and early treatment of diseases are taken.Many biomolecules in the human body play a vital role in regulating various life activities,revealing the variation,denaturation or abnormal concentration of biomolecules in multi-level complex systems such as cells,organs,tissues,living bodies Comprehensive understanding of the overall performance of organisms,providing basic data and theoretical support for behavior and health,so it is of great significance for the detection of biomolecules.At present,the detection methods used in the clinic are complicated and costly.The emergence and development of fluorescent biosensors provide a new effective path for the early detection of diseases.Due to the high requirements for early detection of diseases and the complex biological environment,the development of fluorescent biosensors with high sensitivity,good selectivity,fast and simple,and low cost has become the current research focus.In this paper,using nano-functional materials to reduce the background value and combining signal amplification strategies,we designed and constructed ultra-sensitive and highly selective fluorescent biosensors,and applied them to the detection of biomolecules,providing a new way for the early diagnosis of some diseases.The main research contents are as follows:(1)Based on the existing reports,we used a one-pot method to synthesize amino-functionalized silicon quantum dots,and explored the influence of various factors on the optical properties of the products during the synthesis process.Through a series of characterizations,it can be seen that the surface of the synthesized silicon quantum dots is positively charged,and it is an amination modified silicon quantum dot,which has excitation-dependent fluorescence characteristics.(2)A novel background-eliminated fluorescence assay for sensitive and selective detection of biomolecule has been developed by coupling feroxyhyte nanosheets(δ-FeOOH)with amino-functionalized silicon quantum dot(Si QDs).We select hyaluronidase(HAase)as the modal target to verify the concept.Si QDs/HA-δ-FeOOH nanoassembly was fabricated by self-assembly of positive Si QDs together with negative HA-δ-FeOOH through electrostatic adsorption.By the introduction of hyaluronidase,the nanoassembly exhibits obviously fluorescence signal recovered.Research suggests that under optimized conditions,this strategy exhibits a good linear response to the concentration of HAase in the range of 0.1-12 ng/m L.The detection limit for HAase was 0.02 ng/m L(based on 3σ/S),which was three-order lower than most of the reported fluorescence biosensors for the detection of HAase.Furthermore,this new biosensor has already been applied in the study of urine samples,and the detection results were consistent with those obtained by the clinical tests.(3)A novel low back-ground fluorescent sensor platform for the detection of nucleic acid has been developed based on δ-FeOOH nanosheets integrating with Exonuclease III-assisted target recycling signal amplification.Because of the strong binding ability between the single-strand DNA(ssDNA)and the δ-FeOOH nanosheets,the dye-labeled ssDNA probe would be quenched by δ-FeOOH nanosheets through fluorescence resonance energy transfer(FRET).By using magnetic separate properties of δ-FeOOH,the background signal was separated from the sensor system,and the low background sensor system was obtained.After adding the target DNA,a double-strand DNA complex(ds DNA)would be formed between the target DNA and dye-labeled ssDNA probe.Then,the dye-labeled ssDNA probe in the ds DNA complex would be stepwise hydrolyzed into short fragments from 3′-terminus by Exonuclease III,and the fluorescence signal was recovered due to the weak bind affinity between the short fragments and δ-FeOOH nanosheets.By using the fluorescence quenching ability of δ-FeOOH nanosheets and enzyme-assisted target-recycling signal amplification,this strategy could show an excellent selectivity toward hepatitis C virus DNA with a low detection limit of 10 p M.By simply changing the dye-labeled ssDNA probe sequence,this sensing platform can be developed as a universal approach for the simple,sensitive,and selective detection of different target DNA. |
