This contribution reports on the optical properties of bio-synthesised Eu2O3 nanoparticles bio-engineered for the first time by a green and cost effective method using aqueous fruit extracts of Hyphaene thebaica as an effective chelating and capping agent. The morphology, structural and optical properties of the samples annealed at 500 o C were confirmed by using high resolution transmission electron microscope (HR-TEM), X-Ray diffraction analysis (XRD), UV-vis spectrocopy and PL spectrometer. The XRD results confirmed the characteristic body centered cubic (bcc) structure of Eu2O3 nanoparticles with an average size of 20 nm. HR-TEM revealed square type morphology with an average size of ~ 6 nm. Electron Dispersion Energy dispersive X-ray Spectroscopy (EDS) spectrum confirmed the elemental single phase nature of pure Eu2O3. Furthuremore, the FTIR spectroscopy revealed the intrinsic characteristic peaks of Eu-O bond stretching vibrations. UV-vis reflectance proved that Eu2O3 absorbs in a wide range of the solar spectru from VUV-UV region with bandgap of 5.1 eV. The luminescence properties of such cubic were characterized by an intense red emission centered at 614 nm. It was observed that the biosynthesized Eu2O3 nanoparticles exhibit an efficient red-luminescence & hence a potential material as red phosphor.

Hyphaene thebaica fruits were used for the fabrication of spherical erbium oxide nanoparticles (HT-Er2O3 NPS) using a one-step simple bioreduction process. XRD pattern revealed a highly crystalline and pure phase with crystallite size of ~ 7.5 nm, whereas, the W–H plot revealed crystallite size of 11 nm. FTIR spectra revealed characteristic Er-O atomic vibrations in the fingerprint region. Bandgap was obtained as 5.25 eV using K-M function. The physicochemical and morphological nature was established using Raman spectroscopy, reflectance spectroscopy, SAED and HR-TEM. HT-Er2O3 NPS were further evaluated for antidiabetic potential in mice using in-vivo and in-vitro bioassays. The synthesized HT-Er2O3 NPS were screened for in vitro anti-diabetic potentials against α-glucosidase enzyme and α-amylase enzyme and their antioxidant potential was evaluated using DPPH free radical assay. A dose dependent inhibition was obtained against α-glucosidase (IC50 12 μg/mL) and α-amylase (IC50 78 μg/mL) while good DPPH free radical scavenging potential (IC50 78 μg mL−1) is reported. At 1000 μg/mL, the HT-Er2O3 NPS revealed 90.30% and 92.30% inhibition of α-amylase and α-glucosidase enzymes. HT-Er2O3 NPs treated groups were observed to have better glycemic control in diabetic animals (503.66 ± 5.92*** on day 0 and 185.66 ± 2.60*** on day 21) when compared with positive control glibenclamide treated group. Further, HT-Er2O3 NPS therapy for 21 days caused a considerable effect on serum total lipids, cholesterol, triglycerides, HDL and LDL as compared to untreated diabetic group. In conclusion, our preliminary findings on HT-Er2O3 NPS revealed considerable antidiabetic potential and thus can be an effective candidate for controlling the post-prandial hyperglycemia. However, further studies are encouraged especially taking into consideration the toxicity aspects of the nanomaterial.