Sensitive immunosensor for cancer biomarker based on dual signal amplification strategy of graphene sheets and multienzyme functionalized carbon nanospheres

Graphene-assisted dual amplification strategy for the fabrication of sensitive amperometric immunosensor

A sensitive electrochemical immunosensor with graphene-assisted signal amplification has been developed. In order to construct the base of the immunosensor, a novel hybrid architecture was initially fabricated by combining poly (diallyldimethylammonium chloride) functionalized graphene nanosheets (PDDA-G) and gold nanoparticles (AuNPs) via a simple sonication-induced assembly. The formed hybrid architecture provided an effective matrix for antibody immobilization with good stability and bioactivity. Subsequently, a smart, multilabel, and graphene-based nanoprobe that contains gold nanoparticles functionalized exfoliated graphene oxide and horseradish peroxidase-secondary antibodies was designed for constructing a novel sandwiched electrochemical immunosensor. Enhanced sensitivity was obtained by combining the advantages of high-binding capability and excellent electrical conductivity of hybrid architecture with the multilabel signal amplification. On the basis of the dual signal amplification strategy of graphene-based architecture and the multilabel, the immunosensor displayed excellent analytical performance for the detection of human IgG (HIgG) range from 0.1 to 200 ng/mL with a detection limit of 0.05 ng/mL at 3σ. Moreover, the proposed method showed good precision, acceptable stability and reproducibility, and could be used for the detection of HIgG in real samples. Therefore, the present strategy definitely paves a way for the wide application of graphene in clinical research.

Dual amplification strategy for the fabrication of highly sensitive interleukin-6 amperometric immunosensor based on poly-dopamine

An electrochemical immunosensor was studied for sensitive detection of Interleukin-6 (IL-6) based on a dual amplification mechanism resulting from Au nanoparticles (AuNP)-Poly-dopamine (PDOP) as the sensor platform and multienzyme-antibody functionalized AuNP-PDOP@carbon nanotubes (CNT). The stable and robust film, PDOP, was used to immobilize biomolecules not only for the construction of the sensor platform, but also for the signal labeling. Sensitivity was greatly amplified by using the special platform of AuNP-PDOP and synthesizing horseradish peroxidase (HRP)-antibody (Ab(2)) functionalized AuNP-PDOP@carbon nanotubes (CNT). A linear response range of IL-6 from 4.0 to 8.0 × 10(2) pg mL(-1) with a low detection limit of 1.0 pg mL(-1) was obtained by the amperometry determination. Measurements of IL-6 in human serum gave excellent correlations with standard ELISA assays. Moreover, the immunosensor exhibited high selectivity, good reproducibility, and stability.

Graphene in biomedicine: opportunities and challenges

Graphene, whose discovery won the 2010 Nobel Prize in physics, has been a shining star in the material science in the past few years. Owing to its interesting electrical, optical, mechanical and chemical properties, graphene has found potential applications in a wide range of areas, including biomedicine. In this article, we will summarize the latest progress of using graphene for various biomedical applications, including drug delivery, cancer therapies and biosensing, and discuss the opportunities and challenges in this emerging field.

Prospects of Nanobiomaterials for Biosensing

Progress and development in biosensor development will inevitably focus upon the technology of the nanomaterials that offer promise to solve the biocompatibility and biofouling problems. The biosensors using smart nanomaterials have applications for rapid, specific, sensitive, inexpensive, in-field, on-line and/or real-time detection of pesticides, antibiotics, pathogens, toxins, proteins, microbes, plants, animals, foods, soil, air, and water. Thus, biosensors are excellent analytical tools for pollution monitoring, by which implementation of legislative provisions to safeguard our biosphere could be made effectively plausible. The current trends and challenges with nanomaterials for various applications will have focus biosensor development and miniaturization. All these growing areas will have a remarkable influence on the development of new ultrasensitive biosensing devices to resolve the severe pollution problems in the future that not only challenges the human health but also affects adversely other various comforts to living entities. This review paper summarizes recent progress in the development of biosensors by integrating functional biomolecules with different types of nanomaterials, including metallic nanoparticles, semiconductor nanoparticles, magnetic nanoparticles, inorganic/organic hybrid, dendrimers, and carbon nanotubes/graphene.

Ultrasensitive electrochemical immunoassay for BRCA1 using BMIM·BF₄-coated SBA-15 as labels and functionalized graphene as enhancer

BRCAl is an anti-oncogene in women, who are genetically predisposed to breast and ovary cancer. The detection of BRCA1 can offer an opportunity to characterize the function of genetic features in breast and ovarian cancer and to screen breast or ovarian cancer patients. In this study, we designed a new label and fabricated a novel sandwich-type electrochemical immunoassay for the ultrasensitive detection of BRCAl. Horseradish peroxidase (HRP) was entrapped in the pores of amino-group functionalized SBA-15 and the secondary antibody (Ab₂) combined with SBA-15 by covalent bond. Ionic liquid (IL) was added into the mixed solution of SBA-15/HRP/Ab₂ and application of IL increased the electrochemical activity of HRP and promoted electron transport. The synergistic effect between IL, SBA-15, Ab₂ and HRP could retain the bioactivity of HRP and Ab₂. The sensitivity of the sandwich-type immunosensor using SBA-15/HRP/Ab₂/BMIM·BF₄ as labels for BRCA1 detection was much higher than that using either SBA-15/HRP/Ab₂ or SBA-15/Ab₂ as labels. Under optimal conditions, the electrochemical immunoassay exhibited a wide working range from 0.01 to 15 ng/mL with a detection limit of 4.86 pg/mL BRCA1. The precision, reproducibility, and stability of the immunoassay were acceptable.