| Bioactive molecule,as the basic components of organisms,play important physiological roles or are correlated with pathological changes in the process of life.Detecting biomacromolecules is the priority task of life science research.Biosensors are a critical condition for the precise research of modern life science,and are commonly applied into the recognition,detection,separation and developing of various biomolecules.Doped quantum dots?QDs?are widely used to build optical biosensors,because of their excellent optical properties,high biocompatibility and low biotoxicity.In particular,Mn-doped ZnS QDs optical sensors possess unique room-temperature phosphoresce?RTP?,which avoids the interference from the autofluorescence of organisms,and thus are feasible for detection of biological samples with complex components and strong background fluorescence.In this study,Mn-doped ZnS was surface-functionalized by an appropriate modifier to form optical RTP biosensors,which were used to sensitively detect biomacromolecules?e.g.polysaccharides,proteins,enzymes?.Moreover,the applicability into real biological samples was analyzed.1.In this work,a room-temperature phosphorescent?RTP?PDAD-Mn-ZnS QDs biosensor was constructed with poly?diallyldimethylammonium chloride??PDAD?as the modifier of MPA-capped Mn-ZnS QDs,and used to detect hyaluronic acid?HA?.The newly-added HA induced severe electrostatic interaction with PDAD-Mn-ZnS QDs,leading to the aggregation between PDAD-Mn-ZnS QDs and HA and thereby enhancing RTP.The enhancement of RTP was proportional to the HA concentrations within certain ranges.On this basis,a high-performance HA sensor was built and this sensor had a detection limit of 0.03?g mL-1 and a detection range of 0.082.8?g mL-1.This biosensor is potentially suitable for detection of HA in sodium hyaluronate eye drops and human serum samples without complicated pretreatment.2.PDAD-modified Mn-doped ZnS QDs?PDAD-QDs?/DNA-ROX nanohybrids were constructed via phosphorescent resonance energy transfer?PRET?and then used as optical biosensors for micrococcus nuclease?MNase?activity detection.The PDAD-QDs were prepared as the energy donor,and the DNA-ROX was chosen as the energy receptor.The DNA-ROX could be adsorbed to the surface of PDAD-QDs through electrostatic interaction,which induced PRET and quenched the RTP of PDAD-QDs.The MNase could efficiently degrade the DNA-ROX into small DNA segments,which were less prone to electrostatic interaction with PDAD-QDs,and thus the PRET efficiency decreased.The RTP intensity of PDAD-QDs was gradually enhanced with the increment of MNase concentration.On this basis,we build a RTP sensor for detection of MNase activity.Under the optimal conditions,the change of RTP intensity was proportional to the MNase activity in the range from 2×10-3to 8.0×10-2 U mL-1,and a detection limit of 6×10-4 U mL-1.And the sensor can be used for the determination of MNase in S.aureus medium without complicated pretreatment.3.In this study,Mn-doped ZnS QDs/Eu3+nanohybrids through photoinduced electron-transfer were prepared,and adenosine 5?-monophosphate?AMP?as the substrate,to design a convenient and efficient bioprobe for detection of alkaline phosphatase?ALP?activity.After ALP and AMP were added into the system,under the hydrolytic catalysis of ALP,AMP was rapidly converted into adenosine and phosphate ions.The higher affinity of phosphate ions to Eu3+than Mn-doped ZnS QDs resulted in the formation of a more stable composite,and subsequently,Eu3+was desorbed from the surfaces of Mn-doped ZnS QDs,which restored the RTP of Mn-doped ZnS QDs.Under the optimal conditions,the RTP intensity of the Mn-doped ZnS QDs??RTP?was well linearly related to the logarithm of the ALP activity,with a detection range of 0.1518 U L-1 and a detection limit of 0.065 U L-1.This phosphorescent sensor avoided interference from autofluorescent and scattering light in real biological samples and was highly sensitive to ALP.4.PEI-capped Mn-doped ZnS?PEI-Mn-ZnS?QDs/CBD nanohybrids were prepared through electrostatic self-assembly?PEI:polyethyleneimine;CBD:DNA aptamer of cytochrome C?and used as RTP sensors to detect cytochrome C?Cyt c?.The specific identifying ability between Cyt c and CBD led to the formation of PEI-Mn-ZnS/CBD/Cyt c ternary composite,and Cyt c as the electron receptor would interact with the QDs via electron transfer,leading to the quenching of RTP.Thereby,an optical biosensor for Cyt c detection was built,which had the detection range of 0.1669.96?M and the detection limit of 0.074?M.This simply-designed sensor is adapter-mediated and can specifically detect Cyt c. |
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