Photon-induced synthesis of GO/MnO₂ nanocomposite for biocompatibility evaluation using HEK-293 cells

A graphene oxide/manganese dioxide (GO/MnO₂) nanocomposite was synthesized via a green, photon-induced method under ambient conditions, avoiding high-temperature processing and chemical reductants. X-ray diffraction confirmed the formation of phase-pure tetragonal α-MnO₂ with an average crystallite size of ∼8 nm, accompanied by the disappearance of the GO (001) peak and the emergence of the rGO (002) reflection, indicating partial photoreduction. FESEM and HRTEM analyses revealed uniform dispersion of MnO₂ nanoparticles (10–20 nm) anchored on wrinkled rGO sheets, with a lattice spacing of 0.309 nm corresponding to the (310) plane of α-MnO₂, evidencing strong interfacial coupling. FTIR spectra exhibited characteristic Mn–O and Mn–O–Mn vibrations at ∼460 and 587 cm⁻¹ , confirming robust oxide formation. Nitrogen adsorption–desorption measurements showed a type-IV isotherm with mesoporosity, delivering a high specific surface area of 194.8 m² g⁻¹ , a pore volume of 0.279 cm³ g⁻¹ , and an average pore radius of 1.55 nm. UV–visible spectroscopy revealed broad absorption with an indirect optical band gap of ∼1.71 eV, attributed to interfacial charge transfer and defect-mediated electronic states. Cytocompatibility studies using HEK-293 cells demonstrated high viability (>87 %) across 12.5–200 µg mL⁻¹ , confirming excellent material tolerance. This work highlights photon-induced synthesis as an energy-efficient and scalable route to engineer nanoscale MnO₂–graphene interfaces with controlled structure, porosity, and electronic properties, relevant for redox-active and surface-driven functional applications.