Bio-inspired synthesis of ZnCr2O4 nanoparticles using Crateva religiosa leaf extract and their insights into antituberculosis, anticancer and metal sensing properties

The development of eco-friendly nanomaterials has become a major focus in modern nanotechnology due to their wide-ranging applications in biomedical and environmental fields. In the present investigation, zinc chromite nanoparticles (ZnCr 2 O 4 NPs) were successfully fabricated via a biogenic, sustainable protocol employing Crateva religiosa leaf extract as a natural bio-reductant and bio-stabilizer. A variety of analytical methods were used to assess the structural, optical, and functional characteristics of the biosynthesized NPs. A well-defined cubic spinel ZnCr 2 O 4 phase was confirmed by XRD investigation, and the mean crystallite diameter determined by Scherrer’s equation was 15.33 nm. Fourier-transform infrared studies disclosed the typical Zn–O and Cr–O vibrational bands, affirming the successful production of the spinel framework. UV–Visible diffuse reflectance spectroscopy showed a prominent absorption peak around 288 nm, and the optical band gap was estimated to be 1.27 eV. Morphological analysis indicated the formation of flake-like NPs with good surface features. The synthesized ZnCr 2 O 4 NPs further exhibited moderate anticancer activity, appreciable antitubercular activity, and promising metal-sensing capability toward Cu 2+ ions. The results of this study demonstrate that the green synthesis method using Crateva religiosa extract offers a practical, affordable, and environmentally safe way to produce multifunctional ZnCr 2 O 4 NPs suitable for biomedical and sensing applications.