Metal grafted graphene-based nanomaterials towards cancer theranostic efficacy

Cancer is one of the leading global causes of mortality and morbidity, so it needs early diagnosis and therapies. Traditional diagnostic and therapeutic strategies are inadequate due to several limitations, such as poor specificity, systemic toxicity, and delays, while metal-grafted Gr nanostructures have emerged as promising theranostic platforms due to their unique electronic, optical, and structural properties. Metals such as Fe₃O₄, Au, Ag, TiO₂, Pd, Pt, Bi, ZnO, and Cu grafted onto the Gr surface impart electronic modulation, enhance surface area, flexibility, conductivity, reactivity, biomolecular interactions, and biosensing, thereby enabling precise biomarker detection, targeted drug delivery, imaging, and photothermal/photodynamic therapy (PTT/PDT). Eco-friendly synthesis using plant extracts and microbes offers a sustainable and biocompatible alternative to conventional chemical synthesis. However, challenges remain, such as homogenous doping, synthetic complexity, long-term safety, and clinical scalability. Innovations such as scalable, cost-effective, biocompatible nanofibers, nanopapers, microfluidic, and wearable biosensors are being explored by incorporating AI and advanced diagnostic tools for advanced biomedical devices. In vitro, half maximum inhibitory concentrations (IC₅₀) studies show that size- and dose-dependent nanohybrids such as Fe₃O₄-Gr, γ-Fe₂O₃-Gr, Au-Gr, and Bi-Gr exhibited safer responses at lower concentrations 10-200 µg/mL across HBE, MCF-7, HeLa B, and LNCaP cell lines. Bi-Gr was tested on human liver cancer (HepG2) cell line, which exhibits higher reactivity despite a safer profile of Bi at ~53-88 µg/mL. Pd-Gr and Pt-Gr significantly reduced viability in prostate and ovarian cancer cells at 10-50 µg/mL, while ZnO-Gr, Ag-Gr, and Cu-Gr showed safer activity at lower concentrations on MCF-7. In vivo studies remain limited; median lethal dose (LD₅₀) values for Fe₃O₄-Gr and γ-Fe₂O₃-Gr were determined to be associated with rapid lethal biodistribution observed in the liver, lungs, and spleen. Metal-grafted Gr nanohybrids demonstrate immense potential for multifunctional cancer theranostics, though systematic in vivo toxicity studies still need to be explored by the intravenously administered route to lower the LD₅₀ of nanohybrids for their clinical translation.