Highly sensitive electrochemical immunoassay integrated with polymeric nanocomposites and enhanced SiO 2 @Au core-shell nanobioprobes for SirT1 determination

Ultrasensitive sandwich-typed electrochemical immunoassay for detection of squamous cell carcinoma antigen based on highly branched PtCo nanocrystals and dendritic mesoporous SiO2@AuPt nanoparticles

Squamous cell carcinoma antigen (SCCA) is one of the common squamous cell carcinomas (SCC) in women, which usually works as a tumor biomarker for cervical cancer in diagnostic applications. Herein, bimetallic PtCo highly branched nanocrystals (PtCo BNCs) acted as electrode substrates to construct sandwich-typed electrochemical immunosensor for ultrasensitive detection of SCCA, by using dendritic mesoporous SiO₂@AuPt nanoparticles (DM-SiO₂@AuPt NPs) to adsorb electroactive thionine (Thi) as a signal label. The PtCo BNCs enlarged the loading of the primary antibody (Ab₁), showing effective improvement in conductivity and sensitivity. The DM-SiO₂ had abundant pores to incorporate more Thi, on which the decorated AuPt NPs created a great number of active sites to immobilize the secondary antibodies (Ab₂), thereby obviously amplifying the detection signals. The prepared sensor exhibited a broader linear range (0.001-120 ng mL^-1) and a lower detection limit (0.33 pg mL^-1, S/N = 3), combined with high reproducibility, a low relative standard deviation (below 2.5%) and acceptable recovery (from 98.5 to 110.0%) even in diluted human serum samples. This research provides a substantial platform for clinical diagnosis of SCCA in practice.

Bio-nanogate manipulation on electrode surface as an electrochemical immunosensing strategy for detecting anti-hepatitis B surface antigen

The diagnosis of hepatitis B virus (HBV) and monitoring of the vaccination efficiency against HBV require real-time analysis. The presence of antibody against hepatitis B virus surface antigen (anti-HBsAg) as a result of HBV infection and/or immunization may indicate individual immune status towards HBV. This study investigated the ability of a bio-nanogate-based displacement immunosensing strategy in detecting anti-HBsAg antibody, via nonspecific-binding between polyamidoamine dendrimers encapsulated gold nanoparticles (PAMAM-Au) and the 'antigenic determinant' region (aD) of HBsAg. For this purpose, maltose binding protein harbouring the aD region (MBP-aD) was synthesized as a bioreceptor and immobilized on the screen-printed carbon electrode (SPCE). Following that, PAMAM-Au was deposited on MBP-aD, forming the 'gate' and was used as a monitoring agent. Under optimal conditions, the high specificity of anti-HBsAg antibody towards MBP-aD displaced PAMAM-Au causing the decrement of anodic peak in differential pulse voltammetry (DPV) analysis. The signal changes were proportionally related to the concentration of anti-HBsAg antibody, in a range of 1 - 1000 mIU/mL with a limit of detection (LOD) of 2.5 mIU/mL. The results also showed high specificity and selectivity of the immunosensor platform in detecting anti-HBsAg antibody both in spiked buffer and human serum samples.

Sandwich-type electrochemical immunosensor for carcinoembryonic antigen detection based on the cooperation of a gold-vertical graphene electrode and gold@silica-methylene blue

In this study, a sandwich-type electrochemical (EC) immunosensor was proposed to detect a carcinoembryonic antigen (CEA) based on Au-graphene and Au@SiO₂-methylene blue (MB). The Au nanoparticles (NPs)-vertical graphene (VG) electrode efficiently amplifies the response signal by immobilizing a large amount of the coating antibody (Ab) and is characterized by excellent electrocatalytic activity. The MB nanodot-loaded Au@SiO₂ carriers with core-shell nanostructure and detection Ab were used to construct the Ab-Au@SiO₂-MB label, which improved the sensitivity due to the high EC signal of MB nanodots and the high labeling effect between the detection Ab and MB probe. A novel double-Ab sandwich strategy was developed to further improve the sensitivity and stability based on the same specificity of the coating and detection Abs for the recognition of CEA. Under optimal conditions, the developed EC sensor exhibited a wide linear range from 1 fg mL^-1 to 100 ng mL^-1, with an ultralow detection limit of 0.8 fg mL^-1 (S/N = 3). The feasibility in the clinical application of the EC sensor was verified by the in vitro detection of CEA in human serum.

Facile synthesis of high-performance SiO2@Au core–shell nanoparticles with high SERS activity

This study proposes a facile and general method for fabricating a wide range of high-performance SiO₂@Au core–shell nanoparticles (NPs).

Advances in human chorionic gonadotropin detection technologies: a review

Human chorionic gonadotropin (HCG) is a glycoprotein secreted by placental trophoblast cells in pregnancy. HCG is a heterodimer composed of two different α- and β-subunits, with the latter being unique to HCG. As well as being the most important diagnostic markers for pregnancy, HCG is also a tumor marker, therefore, quantitative detection of HCG is of great value. Numerous advanced technologies have been developed for HCG concentration detection including electrochemical immunoassay, chemiluminescent immunoassay, fluorescence immunoassay, resonance scattering spectrometry, atomic emission spectrometry, radioimmunoassay, MS and so on. Some have pursued simple and easy operation, while others have emphasized on accuracy and applications in clinical medicine. This review provides a comprehensive summary of various methods of detecting HCG.

Carbon Nanomaterial Based Biosensors for Non-Invasive Detection of Cancer and Disease Biomarkers for Clinical Diagnosis

The early diagnosis of diseases, e.g., Parkinson's and Alzheimer's disease, diabetes, and various types of cancer, and monitoring the response of patients to the therapy plays a critical role in clinical treatment; therefore, there is an intensive research for the determination of many clinical analytes. In order to achieve point-of-care sensing in clinical practice, sensitive, selective, cost-effective, simple, reliable, and rapid analytical methods are required. Biosensors have become essential tools in biomarker sensing, in which electrode material and architecture play critical roles in achieving sensitive and stable detection. Carbon nanomaterials in the form of particle/dots, tube/wires, and sheets have recently become indispensable elements of biosensor platforms due to their excellent mechanical, electronic, and optical properties. This review summarizes developments in this lucrative field by presenting major biosensor types and variability of sensor platforms in biomedical applications.