Graphene-based materials are intriguing nanomaterials with applications ranging from nanotechnology-related devices to drug delivery systems and biosensing. Multifunctional graphene platforms were proposed for the detection of several typical biomarkers (i.e., circulating tumor cells, exosomes, circulating nucleic acids, etc.) in liquid biopsy, and numerous methods, including optical, electrochemical, surface-enhanced Raman scattering (SERS), etc., have been developed for their detection. Due to the massive advancements in biology, material chemistry, and analytical technology, it is necessary to review the progress in this field from both medical and chemical sides. Liquid biopsy is considered a revolutionary technique that is opening unexpected perspectives in the early diagnosis and, in therapy monitoring, severe diseases, including cancer, metabolic syndrome, autoimmune, and neurodegenerative disorders. Although nanotechnology based on graphene has been poorly applied for the rapid diagnosis of viral diseases, the extraordinary properties of graphene (i.e., high electronic conductivity, large specific area, and surface functionalization) can be also exploited for the diagnosis of emerging viral diseases, such as the coronavirus disease 2019 (COVID-19). This review aimed to provide a comprehensive and in-depth summarization of the contribution of graphene-based nanomaterials in liquid biopsy, discussing the remaining challenges and the future trend; moreover, the paper gave the first look at the potentiality of graphene in COVID-19 diagnosis.

The ability of multiwalled carbon nanotubes (MWCNTs) covalently functionalized with polyamine chains of different length (ethylenediamine, EDA and tetraethylenepentamine, EPA) to induce the J-aggregation of meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) was investigated in different experimental conditions. Under mild acidic conditions, protonated amino groups allow for the assembly by electrostatic interaction with the diacid form of TPPS, leading to hybrid nanomaterials. The presence of only one pendant amino group for a chain in EDA does not lead to any aggregation, whereas EPA (with four amine groups for chain) is effective in inducing J-aggregation using different mixing protocols. These nanohybrids have been characterized through UV/Vis extinction, fluorescence emission, resonance light scattering and circular dichroism spectroscopy. Their morphology and chemical composition have been elucidated through transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). TEM and STEM analysis evidence single or bundles of MWCNTs in contact with TPPS J-aggregates nanotubes. The nanohybrids are quite stable for days, even in aqueous solutions mimicking physiological medium (NaCl 0.15 M). This property, together with their peculiar optical features in the therapeutic window of visible spectrum, make them potentially useful for biomedical applications.

A series of polymeric silver(I) complexes with Schiff base ligands containing pyridine and 3,5‐halogen substituted phenol moieties were synthesized and characterized by spectroscopic methods and in the case of Ag6 also by X‐ray crystallography. All silver(I) complexes (Ag1–Ag8) were evaluated for their biological activity against a panel of pathogens including the protozoa Trypanosoma cruzi, T. brucei, T. rhodesiense and Leishmania infantum; the bacteria Staphylococcus aureus, Escherichia coli, Mycobacterium tuberculosis H37Ra and the yeast Candida albicans. Cytotoxicity evaluation was carried out on human lung fibroblasts (MRC‐5) and on primary peritoneal mouse macrophages. The most relevant result reveals antileishmanial activity potential with all complexes demonstrating higher potency than the reference drug miltefosine. Complexes with the best antiprotozoal profile (i.e., Ag2 and Ag7) were selected for incorporation into poly (lactic acid) nanoparticles (PLA NPs) with the aim to enhance selectivity. PLA/Ag2 NPs and PLA/Ag7 NPs exhibited adequate physicochemical properties, that is, average size of 263 ± 60 nm and 225 ± 6 nm, respectively, good entrapment efficiency (69% and 63%), loading content (6.2% and 5.7%) and stability. The cytotoxicity of PLA/Ag2 NPs and PLA/Ag7 NPs on MRC‐5 cells was reduced with respect to the “free” metal complexes by ~2‐fold and ~6‐fold, respectively.