Phytohormones (plant hormones) are a class of small-molecule organic compounds synthesized de novo in plants. Although phytohormones are present in trace amounts, they play a key role in regulating plant growth and development, and in response to external stresses. Therefore, the analysis and monitoring of phytohormones have become an important research topic in precision agriculture. Among the various detection methods, electrochemical analysis is favored because of its simplicity, rapidity, high sensitivity, and in-situ monitoring. Graphene and graphene-like carbon materials have abundant sources, exhibiting large specific surface area, and excellent physicochemical properties. Thus, they have been widely used in the preparation of electrochemical biosensors for phytohormone detection. In this paper, the research advances of electrochemical sensors based on graphene and graphene-like carbon materials for phytohormone detection have been reviewed. The properties of graphene and graphene-like carbon materials are first introduced. Then, the research advances of electrochemical biosensors (including conventional electrochemical sensors, photoelectrochemical sensors, and electrochemiluminescence sensors) based on graphene and graphene-like carbon materials for phytohormone detection is summarized, with emphasis on their sensing strategies and the roles of graphene and graphene-like carbon materials in them. Finally, the development of electrochemical sensors based on graphene and graphene-like carbon materials for phytohormone detection is prospected.

The implanted electronic devices require a stable, continuous, and long-lasting energy source to function correctly. These devices are powered by alkaline batteries and lithium ions. When used in implantable or wearable devices, these batteries can pose a threat to human health and the environment. Because of these factors, implantable and wearable devices using enzyme biofuel cells (EBFCs) are receiving a lot of attention. These EBFCs use human physiological fluid to provide longterm control for these devices. Carbon nanomaterials have successfully been demonstrated in enzymatic biofuel cells to improve applications by increasing current and power density; they have the potential to enhance EBFC efficiency. This review summarizes the fundamental process of EBFC compounds based on carbon nanomaterials before delving into the most recent advancements that have been tested and used as implantable and wearable self-power sources.

Nanomaterials (NMs) are gradually becoming pervasive in the modern world, entering every application for improving the quality of life. Multifaceted uses of NMs in curing diseases, biomedical instrumentation, bioimaging, drugs, and gene delivery, display devices, nanosensors, and biomarkers in several fields ranging from agriculture to industries, healthcare, and environment, have been well recognized. Carbon-based nanomaterials (CNMs) constitute a major type of NMs with broad-spectrum applications including their uses in agriculture. These are synthesized in large quantities via synthetic and biological approaches. Biological approaches are gaining appreciation and momentum, owing to the advantages associated with them, major being their environment friendly or ‘Green’ nature. This topical review focuses on the preparation of CNMs using natural resources, i.e., using the Green Nanotechnology. The up-to-date compilation presented here includes most of the popular green technological methods of producing the CNMs and their immediate uses as anticancer agents, in bio-labelling, as biosensors, in bio-remediation, in cell imaging, in fluorescent inks, and fluorescent dyes, as plant growth inducing agents, in nano-probes, in light-emitting devices and other applications. It is intended to update the reader with the state-of-the-art knowledge about the green technological methods for synthesizing CNMs, their uses, current trends, challenges, and future outlook on the topic.