Ultrasensitive Electrochemical Immunoassay For Prolactin Based On The Noble Metal Nanocomposites

Objective:Prolactin（PRL）,as a polypeptide hormone,is synthesized and released by the anterior pituitary gland,which plays various physiological functions in the human body and is very significant for maintaining the homeostasis of the internal environment.The disorder of PRL is associated with many diseases,which is one of the most common problems in clinical endocrine.Accurate and quantitative detection of PRL is of vital importance for the prevention and diagnosis of endocrine diseases.Therefore,this study intends to construct a novel type of electrochemical immunosensor for the ultrasensitive detection of PRL based on highly branched palladium platinum nanodendrites（PdPt NDs）and Fe-based metal organic framework NH₂-MIL-53（Fe）.Methods:PdPt NDs were synthesized by a simple one-pot method at room temperature,and then efficiently loaded on NH₂-MIL-53（Fe）to form PdPt NDs@NH₂-MIL-53（Fe）composite material.Subsequently,the composite material was applied as signal label of secondary antibody（Ab₂）.Gold nanoparticles coated amino-functionalized graphene sheet（Au NPs@NH₂-GS）was modified on glassy carbon electrode（GCE）for loading primary antibodies（Ab₁）.In the presence of PRL,a stable"sandwich"structure could be constructed due to the specific reaction between antigen and antibody.PdPt NDs@NH₂-MIL-53（Fe）had excellent peroxidase-like activity,which could significantly catalyze the substrate H₂O₂to produce electrochemical signal,and the intensity of electrochemical signal was positively correlated with the concentration of PRL.Based on this,the chronoamperometry（i-t）was used to monitor the electrochemical signal for ultrasensitive detection of PRL.Results:The strongest current signal could be obtained when the pH of phosphate buffered saline（PBS）was 7.4 and the concentrations of PdPt NDs@NH₂-MIL-53（Fe）and Au NPs@NH₂-GS were both 2.0 mg/mL.Under the optimum experimental conditions,the linear range of the sensor was 0.005～500 ng/mL,and the detection limit was as low as 1.15 pg/mL.Meanwhile,multiple sets of comparative experiments confirmed that the immunosensor had superior reproducibility,specificity and stability.Furthermore,the immunosensor were employed for PRL detection in the clinical serum samples,achieving comparable results with clinical commercial chemiluminescent immunoassay（CLIA）,and the relative error between the two methods was-4.95%to 5.13%.Conclusion:In this study,a novel electrochemical immunosensor was constructed for the detection of PRL based on excellent catalytic activity PdPt NDs@NH₂-MIL-53（Fe）and high conductivity Au NPs@NH₂-GS.The proposed immunoassay not only had a wide linear range and extremely low detection limit,but also demonstrated superior reproducibility,specificity and stability.More importantly,this method could realize ultrasensitive detection of PRL in complex serum samples,which confirmed great potential in clinical practical applications,providing a robust technical support for early diagnosis,treatment and prevention of clinically related diseases.