In Situ Synthesis of a Hydroxyapatite and Reduced Graphene Oxide Composite for Potential Electrochemical Biosensing...

Hydroxyapatite/reduced graphene oxide (HA/rGO) composites are extensively used in numerous applications, including tissue engineering, energy storage, catalysis, and electrochemical sensing. In this study, a novel microwave hydrothermal-assisted coprecipitation method was implemented to synthesize an in situ HA/rGO composite for potential electrochemical biosensing applications. The structural, optical, and morphological properties were thoroughly analyzed using XRD, Raman spectroscopy, FTIR, STXM, and SEM. Rietveld refinement confirmed the presence of a hexagonal crystalline phase in the HA/rGO composite with a mean crystallite size of 28.1 nm. Raman spectroscopy revealed characteristic vibrational modes of each precursor, while STXM spectra displayed electronic transitions corresponding to rGO (C 1s to π* and σ* levels) as well as Ca L-edge and O and P K-edge transitions of HA, confirming a composite material. FTIR analysis confirmed the reduction of GO to rGO by tracking the presence and disappearance of oxygen-functional groups in the graphitic structure. Electron microscopy revealed that HA nanorods, averaging 75 nm in length, were uniformly distributed along the surface and edges of the rGO layers.