Construction Of Electrochemiluminescence Aptasensor Based On Sulfide And Graphene Functional Nanomaterials And Its Applications

Electrochemiluminescence?ECL?is a kind of detection technology which combines electrochemistry and chemiluminescence,with the advantages of high sensitivity,good selectivity,wide linear range etc.Malignant tumors have become a major threat to human health.Early detection and diagnosis of tumor prevention and treatment are very important.In order to achieve the sensitive detection of tumor markers,the combination of ECL detection technology and signal amplification strategy was utilized to make use of the excellent properties of nanomaterials and the specific recognition of aptamer.It is important to construct a highly sensitive and highly selective ECL aptasensor and carry out research on the application of life analysis chemistry,which is one of the forefronts of analytical chemistry.In this paper,we used small particle size quantum,luminol and semiconductor sulfide materials as ECL sensing interfaces,and combined with ferrocene–graphene,hemin–graphene nanosheets and graphene oxide–AuNRs–glucose oxidase–streptavidin complexes as biologically recognizable nanoprobe.Moeover,the enzyme catalyzed bioprecipitation technology was also introduced into ECL sensors to improve the detection sensitivity,expecting to provide a new method for accurate and sensitive detection of tumor markers.The main innovations and research contents are as follows:1.A novel competitive ECL aptasensor based on CdSe/ZnS QDs functionalized MoS₂ modified electrode was developed for sensitive immunoglobulin E?IgE?detection using horseradish peroxidase?HRP?catalyzed biocatalytic precipitation?BCP?for signal amplification.QDs were assembled on MoS₂ as a sensing platform to connect the complementary DNA?cDNA?of IgE aptamer.By hybridization,the HRP and IgE aptamer functionalized AuNPs?aptamer–AuNPs–HRP?signal probes were fixed on the electodes.Without IgE,a large amount of signal probes hybridizes with cDNA,the presence of HRP would stimulate the BCP onto the electrode surface,thereby impairing the ECL emission dramatically.In the presence of IgE,the signal probe would capture IgE to form conjugation,released from the electrode accompanying decrease of HRP and increase of ECL intensity.The aptasensor displaysa liner range from 0.5 pmol L^-1 to 0.5 nmol L^-1 with the detection limit of 0.18 pmol L^-1?S/N = 3?.Moreover,the sensor was successfully used to detemine IgE in human serum samples with the recoveries of 85.0% –107.5%.2.A novel and competitive electrochemiluminescence?ECL?aptasensor for prostate specific antigen?PSA?assay was constructed using gold nanorods functionalized graphene oxide?GO@AuNRs?multilabeled with glucose oxidase?GOD?and streptavidin?SA?toward luminol-based ECL system.A strong initial ECL signal was achieved by electrodeposited gold?DpAu?on the electrode because of AuNPs motivating the luminol ECL signal.The signal probes prepared by loading GOD and SA-biotin-DNA on GO@AuNRs were used for achieving multiple signal amplification.In the absence of PSA,the signal probes can be attached on the electrode by hybridization reaction between PSA aptamer and biotin-DNA.In this state,the GOD loaded on the probe could catalyze glucose to in situ produce H₂O₂ and then AuNRs catalyze H₂O₂ to generate abundant reactive oxygen species?ROSs?in luminol ECL reaction.Both the high-content GOD and AuNRs in the signal probe amplified the ECL signal in the ECL system.Moreover,the combination of SA with biotin-DNA further expands ECL intensity.The integration of such amplifying effects in this protocol endows the aptasensor with high sensitivity and good selectivity for PSA detection.This aptasensor exhibits a linear relation in the range of 0.5 pg mL^-1 to 5.0ng mL^-1 with the detection limit of 0.17 pg mL^-1?S/N = 3?.Besides,the strategy was successfully applied in determination of human serum samples with recovery of81.4%–116.0%.3.A signal–switchable electrochemiluminescence?ECL?aptasensor was presented for sensitive prostate specific antigen?PSA?assay using ferrocene–graphene sheets for high–efficiency quenching of ECL from Au–CdS nanomateials.First,Au-CdS was employed as luminophore,exhibiting strong and stable ECL intensity.The captured DNA?cDNA?was assembled on the electrode,and following hybridized with half of base sequence of PSA aptamer.Then,the Fc-GNs nanosheets were immobilized on themodified electrode by strong ?-? stacking effect between DNA and graphene.Due to the steric hindrance of GNs and the quenching performance of Fc to CdS emission,the ECL signal was significantly decreased with the signal switched “off” state.In the presence of PSA,the PSA is preferentially combined with aptamer and released from the GNs surface,accompanying the ECL signal enhancement.With the transformation of signal from “off” to “on”,the aptasensor displayed high sensitivity for PSA detection with a linear range from 1 pg mL_–1 to 25 ng mL_–1 and a detection limit of0.38 pg mL_–1?S/N = 3?.Moreover,this method could be successfully applied to the determination of PSA in human serum samples with recoveries of 85.8–104.0%.4.A sandwich–like electrochemiluminescence?ECL?aptasensor for carcinoembryonic antigen?CEA?assay was fabricated based on the dual quenching effect from hemin–graphene?H–rGO?nanosheet and enzymatic biocatalytic precipitation?BCP?on the Au–CdS nanocomposites–based ECL system.In this aptasensor platform,flower–like spherical Au–CdS nanocomposites were used as ECL luminophores and exhibited a strong ECL signal.The rGO nanosheet was used as a supporter to immobilize hemin molecules via ?–? stacking interactions.Due to the steric hindrance of rGO,the ECL intensity decreased by the construction of the sandwich mode of “CEA aptamer I?NH₂–DNA?–CEA–signal probe”.In the process of BCP,the ECL intensity further decreased because the hemin with intrinsic peroxidase–like catalytic activity could oxidize the 4–chloro–1–naphthol?4–CN?to produce an insoluble precipitation on the sensor.Using this dual quenching strategy,the prepared aptasensor exhibits a linear range from 0.8 pg mL –1to 4 ng m L–1 and a detection limit of 0.28 pg mL_–1.This ECL aptasensor has simple design and undemanding in operation and was utilized to determine the content of CEA in complex samples with recoveries of 95.0% to 115.8%.Moreover,no any chemical modification of aptamer was required,suggesting that the proposed ECL aptasensor could be applied for the detection of diverse proteins just by altering the aptamer sequence.