Carbon nanotubes (CNTs) have remarkable mechanical, thermal, electronic, and biological properties due to their particular atomic structure made of graphene sheets that are rolled into cylindrical tubes. Due to their outstanding properties, CNTs have been used in several technological fields. Currently, the most prominent research area of CNTs focuses on biomedical applications, using these materials to produce hybrid biosensors, drug delivery systems, and high performance composites for implants. Although a great number of research studies have already shown the advantages of CNT-based biomedical devices, their clinical use for in vivo application has not been consummated. Concerns related to their toxicity, biosafety, and biodegradation still remain. The effect of CNTs on the human body and the ecosystem is not well established, especially due to the lack of standardization of toxicological tests, which generate contradictions in the results. CNTs’ toxicity must be clarified to enable the medical use of these exceptional materials in the near future. In this review, we summarize recent advances in developing biosensors, drug delivery systems, and implants using CNTs as smart biomaterials to identify pathogens, load/deliver drugs and enhance the mechanical and antimicrobial performance of implants.

Energy storage is currently one of the most significant technological challenges globally, and supercapacitor is a prominent candidate over batteries due to its ability for fast charging and long lifetime. Supercapacitors typically use porous carbon as electrodes, because of both the high conductivity and surface area of the material. However, the state-of-the-art porous carbon described in the literature uses toxic chemicals and complex procedures that enhance costs and pollute the environment. Thus, a more sustainable procedure to produce porous carbon is highly desirable. In this context, xerogel-like carbons were prepared by a new, cheap, simple route to polymerization reactions of tannin-formaldehyde in a bio-oil by-product. Using bio-oil in its natural pH allowed a cost reduction and avoided using new reactants to change the reactional medium. Textural properties and electrochemical performances were improved by fast activating the material per 20 min. The non-activated carbon xerogel presented a capacitance of 92 F/g, while the activated one had 132 F/g, given that 77% of the components used are eco-friendly. These results demonstrate that renewable materials may find applications as carbon electrodes for supercapacitors. Overhauling the synthesis route with a different pH or replacing formaldehyde may enhance performance or provide a 100% sustainable carbon electrode.

This study aimed to synthesize a composite material composed of bio-based, porous carbon matrix and Cu nanoparticles through a simple, low-cost, and environmentally friendly method. Concentrated Kraft black liquor was used as a carbon precursor, and Cu nanoparticles were homogeneously deposited on the carbon matrix using electrochemical deposition. The textural properties determined using N₂ isotherms indicated increased surface area of a carbon matrix with a micro-mesoporous structure. Voltammetric tests demonstrated that the composite exhibited catalytic properties for electrochemical CO₂ reduction. Compared to the bio-based, porous carbon sample (C matrix), the bio-based carbon electrode electrochemically decorated with Cu nanoparticles (C–Cu composite) exhibited increased current values of approximately 2.4 times, a potential shift of approximately 90 mV, and an onset potential of −1.02 V, under CO₂ saturation.

In this work, the synthesis of activated carbon from the bark of the Magonia pubescens (known as Tingui) and its efficiency in the removal of diclofenac sodium through batch adsorption tests and physical-chemical characterizations were investigated. The phytotoxicity of this material was also evaluated through germination and root growth of Lactuca sativa seeds. According to the experimental design performed for the synthesis of Tingui carbon, the optimized temperature and residence time for the production of this adsorbent were 550 °C and 120 min, respectively. The equilibrium time was reached in 600 min and the theoretical model that best fitted the kinetic data was the Elovich model. The BET was the best fit for the adsorption isotherm dataThis indicates that the adsorption process of sodium diclofenac by activated carbon can occur by two different mechanisms, monolayer and/or multilayer adsorption, depending on the conditions employed in the process, such as temperature and adsorbate concentration. The thermodynamic study showed that the process was favourable and spontaneous in the temperature range evaluated. Furthermore, the characterizations showed by TG/DTG and FTIR analyses that the temperature throughout the process had a marked impact on the degradation of the organic constituents of the biomass and the appearance of distinct functional groups that contributed to the adsorption process of diclofenac sodium. Finally, the toxicity tests recognized that this adsorbent does not affect the germination of L. sativa species. Thus, this adsorbent may become a novel and viable option to be used in the removal of sodium diclofenac.