Label-free Aptasensor based on Electrodeposition of Gold Nanoparticles on Graphene and Its Application in the Quantification of Adenosine Triphosphate

Graphene Based Nanohybrid Aptasensors in Environmental Monitoring: Concepts, Design and Future Outlook

In view of ever-increasing environmental pollution, there is an immediate requirement to promote cheap, multiplexed, sensitive and fast biosensing systems to monitor these pollutants or contaminants. Aptamers have shown numerous advantages in being used as molecular recognition elements in various biosensing devices. Graphene and graphene-based materials/nanohybrids combined with several detection methods exhibit great potential owing to their exceptional optical, electronic and physicochemical properties which can be employed extensively to monitor environmental contaminants. For environmental monitoring applications, aptamers have been successfully combined with graphene-based nanohybrids to produce a wide range of innovative methodologies. Aptamers are immobilized at the surface of graphene based nanohybrids via covalent and non-covalent strategies. This review highlights the design, working principle, recent developmental advances and applications of graphene based nanohybrid aptasensors (GNH-Apts) (since January 2014 to September 2021) with a special emphasis on two major signal-transduction methods, i.e., optical and electrochemical for the monitoring of pesticides, heavy metals, bacteria, antibiotics, and organic compounds from different environmental samples (e.g., water, soil and related). Lastly, the challenges confronted by scientists and the possible future outlook have also been addressed. It is expected that high-performance graphene-based nanohybrid aptasensors would find broad applications in the field of environmental monitoring.

Electrochemical aptasensor based on Mo2C/Mo2N and gold nanoparticles for determination of chlorpyrifos

Two-dimensional Mo₂C/Mo₂N composites were synthesized by high temperature ball milling and used as support materials for fabricating a chlorpyrifos (CPF) aptasensor. Gold nanoparticles (Au NPs) were electrodeposited on the surface of a Mo₂C/Mo₂N-modified electrode to connect with the ferrocene (Fc) probe via Au-S bonds. The Fc probe can hybridize with the aptamer probe to form a double-stranded structure. The addition of CPF made the double strands melt and the Fc probe approached the surface of the electrode, thereby resulting in amplification of the electrochemical response. The current response of the aptasensor for detecting CPF in solutions linearly varied from 0 to 400 ng mL^-1 (with a maximum at 0.98 V vs. Ag/AgCl). The Au NPs/Mo₂C/Mo₂N composites exhibited satisfactory electrochemical behavior due to their excellent electrical conductivity and large surface area. This ultrasensitive aptasensor showed a low limit of detection of 0.036 ng mL^-1. It was applied to determine CPF in real samples with acceptable recoveries from 94.7 to 116.7%, and the relative standard deviation was from 2.57 to 7.08%.Graphical abstract Schematic diagram of the manufacturing process of the aptasensor. Electrochemical aptasensor based on Mo₂C/Mo₂N/Au NP composites show excellent performance in detecting CPF.

Graphene/aptamer probes for small molecule detection: from in vitro test to in situ imaging

Small molecules are key targets in molecular biology, environmental issues, medicine and food industry. However, small molecules are challenging to be detected due to the difficulty of their recognition, especially in complex samples, such as in situ in cells or animals. The emergence of graphene/aptamer probes offers an excellent opportunity for small molecule quantification owing to their appealing attributes such as high selectivity, sensitivity, and low cost, as well as the potential for probing small molecules in living cells or animals. This paper (with 130 refs.) will review the application of graphene/aptamer probes for small molecule detection. We present the recent progress in the design and development of graphene/aptamer probes enabling highly specific, sensitive and rapid detection of small molecules. Emphasis is placed on the success in their development and application for monitoring small molecules in living cells and in vivo systems. By discussing the key advances in this field, we wish to inspire more research work of the development of graphene/aptamer probes for both on-site or in situ detection of small molecules and its applications for investigating the functions of small molecules in cells in a dynamic way. Graphical abstract Graphene/aptamer probes can be used to construct different platforms for detecting small molecules with high specificity and sensitivity, both in vitro and in situ in living cells and animals.

Graphene-based aptasensors: from molecule-interface interactions to sensor design and biomedical diagnostics

Graphene-based nanomaterials have been widely utilized to fabricate various biosensors for environmental monitoring, food safety, and biomedical diagnostics. The combination of aptamers with graphene for creating biofunctional nanocomposites improved the sensitivity and selectivity of fabricated biosensors due to the unique molecular recognition and biocompatibility of aptamers. In this review, we highlight recent advances in the design, fabrication, and biomedical sensing application of graphene-based aptasensors within the last five years (2013-current). The typical studies on the biomedical fluorescence, colorimetric, electrochemical, electrochemiluminescence, photoelectrochemical, electronic, and force-based sensing of DNA, proteins, enzymes, small molecules, ions, and others are demonstrated and discussed in detail. More attention is paid to a few key points such as the conjugation of aptamers with graphene materials, the fabrication strategies of sensor architectures, and the importance of aptamers on improving the sensing performances. It is expected that this work will provide preliminary and useful guidance for readers to understand the fabrication of graphene-based biosensors and the corresponding sensing mechanisms in one way, and in another way will be helpful to develop novel high performance aptasensors for biological analysis and detection.

Advances in the design of nanomaterial-based electrochemical affinity and enzymatic biosensors for metabolic biomarkers: A review

This review (with 340 refs) focuses on methods for specific and sensitive detection of metabolites for diagnostic purposes, with particular emphasis on electrochemical nanomaterial-based sensors. It also covers novel candidate metabolites as potential biomarkers for diseases such as neurodegenerative diseases, autism spectrum disorder and hepatitis. Following an introduction into the field of metabolic biomarkers, a first major section classifies electrochemical biosensors according to the bioreceptor type (enzymatic, immuno, apta and peptide based sensors). A next section covers applications of nanomaterials in electrochemical biosensing (with subsections on the classification of nanomaterials, electrochemical approaches for signal generation and amplification using nanomaterials, and on nanomaterials as tags). A next large sections treats candidate metabolic biomarkers for diagnosis of diseases (in the context with metabolomics), with subsections on biomarkers for neurodegenerative diseases, autism spectrum disorder and hepatitis. The Conclusion addresses current challenges and future perspectives. Graphical abstract This review focuses on the recent developments in electrochemical biosensors based on the use of nanomaterials for the detection of metabolic biomarkers. It covers the critical metabolites for some diseases such as neurodegenerative diseases, autism spectrum disorder and hepatitis.

Recent advances on aptamer-based biosensors to detection of platelet-derived growth factor

Platelet-derived growth factor (PDGF-BB), a significant serum cytokine, is an important protein biomarker in diagnosis and recognition of cancer, which straightly rolled in proceeding of various cell transformations, including tumor growth and its development. Fibrosis, atherosclerosis are certain appalling diseases, which PDGF-BB is near to them. Generally, the expression amount of PDGF-BB increases in human life-threatening tumors serving as an indicator for tumor angiogenesis. Thus, identification and quantification of PDGF-BB in biomedical fields are particularly important. Affinity chromatography, immunohistochemical methods and enzyme-linked immunosorbent assay (ELISA), conventional methods for PDGF-BB detection, requiring high-cost and complicated instrumentation, take too much time and offer deficient sensitivity and selectivity, which restrict their usage in real applications. Hence, it is essential to design and build enhanced systems and platforms for the recognition and quantification of protein biomarkers. In the past few years, biosensors especially aptasensors have been received noticeable attention for the detection of PDGF-BB owing to their high sensitivity, selectivity, accuracy, fast response, and low cost. Since the role and importance of developing aptasensors in cancer diagnosis is undeniable. In this review, optical and electrochemical aptasensors, which have been applied by many researchers for PDGF-BB cancer biomarker detection, have been mentioned and merits and demerits of them have been explained and compared. Efforts related to design and development of aptamer-based biosensors using nanoparticles for sensitive and selective detection of PDGF-BB have been reviewed considering: Aptamer importance as recognition elements, principal, application and the recent improvements and developments of aptamer based optical and electrochemical methods. In addition, commercial biosensors and future perspectives for rapid and on-site detection of PDGF-BB have been summarized.

Sensitive electrochemical determination of rifampicin using gold nanoparticles/poly-melamine nanocomposite

Green and facile method for fabrication of a conductive polymer–Au nanocomposite platform as a novel electrochemical sensing layer for rifampicin.

Electrochemical Aptasensor for Myoglobin-Specific Recognition Based on Porphyrin Functionalized Graphene-Conjugated Gold Nanocomposites

In this work, a novel electrochemical aptasensor was developed for sensitive and selective detection of myoglobin based on meso-tetra (4-carboxyphenyl) porphyrin-functionalized graphene-conjugated gold nanoparticles (TCPP–Gr/AuNPs). Due to its good electric conductivity, large specific surface area, and excellent mechanical properties, TCPP–Gr/AuNPs can act as an enhanced material for the electrochemical detection of myoglobin. Meanwhile, it provides an effective matrix for immobilizing myoglobin-binding aptamer (MbBA). The electrochemical aptasensor has a sensitive response to myoglobin in a linear range from 2.0 × 10⁻¹¹ M to 7.7 × 10⁻⁷ M with a detection limit of 6.7 × 10⁻¹² M (S/N = 3). Furthermore, the method has the merits of high sensitivity, low price, and high specificity. Our work will supply new horizons for the diagnostic applications of graphene-based materials in biomedicine and biosensors.

Carbon nanomaterials-based electrochemical aptasensors

Carbon nanomaterials (CNMs) have attracted increasing attention due to their unique electrical, optical, thermal, mechanical and chemical properties. CNMs are extensively applied in electronic, optoelectronic, photovoltaic and sensing devices fields, especially in bioassay technology. These excellent properties significantly depend on not only the functional atomic structures of CNMs, but also the interactions with other materials, such as gold nanoparticles, SiO2, chitosan, etc. This review systematically summarizes applications of CNMs in electrochemical aptasensors (ECASs). Firstly, definition and development of ECASs are introduced. Secondly, different ways of ECASs about working principles, classification and construction of CNMs are illustrated. Thirdly, the applications of different CNMs used in ECASs are discussed. In this review, different types of CNMs are involved such as carbon nanotubes, graphene, graphene oxide, etc. Besides, the newly emerging CNMs and CNMs-based composites are also discoursed. Finally, we demonstrate the future prospects of CNMs-based ECASs, and some suggestions about the near future development of CNMs-based ECASs are highlighted.