This study describes Green synthesis of two metal oxide nanoparticles MnO₂NPs and CuONPs using the oat biomass. The electrocatalytic activity of the synthesized metal oxide nanoparticles was investigated by fabricating two modified sensors enriched with MnO₂NPs and CuONPs as a coated layer on the surface of the sensors and utilized to quantify antibacterial drugs cephalexin (CPX) and cefazolin (CFZ) in their commercial products and biosamples. The tested drugs were incorporated with the precipitating agents phosphomolybdic acid and phosphotungstic acid to form CPX-PM and CFZ-PT as electroactive materials, respectively. Conductivity enhancement of the fabricated modified sensors CPX-PM-MnO₂NPs and CFZ-PT-CuONPs was determined and the outcomes compared to the results obtained from the conventional types of the same sensors. Linear relationships were recorded between the sensory potentials of the enriched metal oxide nanoparticles in the ranges of 1.0 × 10^-8-1.0 × 10^-2 and 1.0 × 10^-10-1.0 × 10^-2 mol L^-1 with lower limits of detection 5.6 × 10^-9 and 5.7 × 10^-11 mol L^-1 for CPX-PM-MnO₂NPs and CFZ-PT-CuONPs with respect to 1.0 × 10^-6-1.0 × 10^-2 mol L^-1 of their conventional coated wire types. The fabricated sensors provide excellent sensitivity and selectivity towards the determination of CPX and CFZ in its commercial and biosamples. GRAPHICAL ABSTRACT

The existing study pronounces two newly developed spectrofluorimetric probes for the assay of ambroxol hydrochloride in its authentic and commercial formulations using an aluminum chelating complex and a biogenically mediated and synthesized aluminum oxide nanoparticles (Al₂O₃NPs) from Lavandula spica flower extract. The first probe is based on the formation of an aluminum charge transfer complex. However, the second probe is based on the effect of the unique optical characteristics of Al₂O₃NPs in the enhancement of fluorescence detection. The biogenically synthesized Al₂O₃NPs were confirmed using various spectroscopic and microscopic investigations. The fluorescence detections in the two probes were measured at a λ_ex of 260 and 244 and a λ_em of 460 and 369 nm for the two suggested probes, respectively. The findings showed that the fluorescence intensity (FI) covered linear concentration ranges of 0.1–200 ng mL⁻¹ and 1.0–100 ng mL⁻¹ with a regression of ˃0.999 for AMH-Al₂O₃NPs-SDS and AMH-Al(NO₃)₃-SDS, respectively. The lower detection and quantification limits were evaluated and found to be 0.04 and 0.1 ng mL⁻¹ and 0.7 and 0.1 ng/mL⁻¹ for the abovementioned fluorescence probes, respectively. The two suggested probes were successfully applied for the assay of ambroxol hydrochloride (AMH) with excellent percentage recoveries of 99.65% and 99.85%, respectively. Excipients such as glycerol and benzoic acid used as additives in pharmaceutical preparations, several common cations, and amino acids, as well as sugars, were all found to have no interference with the approach.