A sandwich-type immunosensor using Pd-Pt nanocrystals as labels for sensitive detection of human tissue polypeptide antigen

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.

Recent advances in biosensor development for the detection of cancer biomarkers

Cancer is the second largest disease throughout the world with an increasing mortality rate over the past few years. The patient's survival rate is uncertain due to the limitations of cancer diagnosis and therapy. Early diagnosis of cancer is decisive for its successful treatment. A biomarker-based cancer diagnosis may significantly improve the early diagnosis and subsequent treatment. Biosensors play a crucial role in the detection of biomarkers as they are easy to use, portable, and can do analysis in real time. This review describes various biosensors designed for detecting nucleic acid and protein-based cancer biomarkers for cancer diagnosis. It mainly lays emphasis on different approaches to use electrochemical, optical, and mass-based transduction systems in cancer biomarker detection. It also highlights the analytical performances of various biosensor designs concerning cancer biomarkers in detail.

Ultrasensitive electrochemical immunosensor for quantitative detection of tumor specific growth factor by using Ag@CeO2 nanocomposite as labels

In this paper, an ultrasensitive electrochemical immunosensor was developed for the detection of tumor specific growth factor (TSGF). Reduced graphene oxide-tetraethylene pentamine (rGO-TEPA) was used to modify the surface of glassy carbon electrode (GCE). Meanwhile, Ag@CeO2 nanocomposite was synthesized and applied as secondary-antibody (Ab2) labels for the fabrication of the immunosensor. The amperometric response of the immunosensor for the reduction of H2O2 was recorded. Simultaneously, electrochemical impedance spectroscopy (EIS) and Cyclic voltammetry (CV) were used to characterize the fabrication process of the immunosensor. The anti-TSGF primary antibody (Ab1) was immobilized onto the rGO-TEPA modified GCE via cross-linking with glutaraldehyde (GA). And then the TSGF antigen and Ab2-Ag@CeO2 were modified onto the electrode surface in sequence. Under the optimal conditions, the immunosensor exhibited a wide linear range (0.500-100pg/mL), a low detection limit (0.2pg/mL), good reproducibility, acceptable selectivity and excellent stability. The proposed sensing strategy may provide a potential application in the detection of other cancer biomarkers.

Ultrasensitive electrochemical aptasensor for the detection of thrombin based on dual signal amplification strategy of Au@GS and DNA-CoPd NPs conjugates

In this work, an ultrasensitive electrochemical aptasensor for the detection of thrombin was developed based on Au nanoparticles decorated graphene sheet (Au@GS) and CoPd binary nanoparticles (CoPd NPs). A sulfydryl-labeled thrombin capture probe (Apt1) and a biotin-labeled thrombin reporter probe (Apt2) were designed to achieve a sandwich-type strategy. Au@GS was used as a sensing platform for the facile immobilization of Apt1 through Au-S bond, forming a sensing interface for thrombin. The specific recognition of thrombin induced the attachment of Apt2-CoPd NPs to the electrode. The labeled CoPd NPs showed good catalytic properties toward the reduction of H2O2, resulting in an amperometric signal. The amperometric response was correlated to the thrombin concentration in sample solutions. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) confirmed the successful fabrication of the aptasensor. A linear response to thrombin in the range of 0.01-2.00 ng mL(-1) with a low detection limit (5 pg mL(-1)) was achieved. The proposed aptasensor showed good selectivity, good reproducibility and acceptable stability. This proposed strategy may find many potential applications in the detection of other biomolecules.

Biosensors Incorporating Bimetallic Nanoparticles

This article presents a review of electrochemical bio-sensing for target analytes based on the use of electrocatalytic bimetallic nanoparticles (NPs), which can improve both the sensitivity and selectivity of biosensors. The review moves quickly from an introduction to the field of bio-sensing, to the importance of biosensors in today's society, the nature of the electrochemical methods employed and the attendant problems encountered. The role of electrocatalysts is introduced with reference to the three generations of biosensors. The contributions made by previous workers using bimetallic constructs, grouped by target analyte, are then examined in detail; following which, the synthesis and characterization of the catalytic particles is examined prior to a summary of the current state of endeavor. Finally, some perspectives for the future of bimetallic NPs in biosensors are given.

A sensitive electrochemical immunosensor for the detection of squamous cell carcinoma antigen by using PtAu nanoparticles loaded on TiO2colloidal spheres as labels

A sensitive sandwich-type electrochemical immunosensor for detection of squamous cell carcinoma antigen (SCCA) was developed by using PtAu nanoparticles loaded on TiO₂colloidal spheres (PtAu/TiO₂) as secondary-antibody (Ab₂) labels.

An ultrasensitive electrochemical immunosensor for the detection of CD146 based on TiO2 colloidal sphere laden Au/Pd nanoparticles

An ultrasensitive electrochemical immunosensor was developed for detecting CD146. rGO-TEPA enhanced the loading capacity of Ab₁ and facilitated the electron transfer. Au and Pd nanoparticles on the TiO₂ colloidal sphere facilitated the decomposition of H₂O₂. The immunosensor exhibited an extremely low detection limit of 1.6 pg mL⁻¹ for CD146.