Ultrasonic-assisted green synthesis of schiff base-functionalized CdS nanoparticles with enhanced optical, anticancer, and antibacterial properties

Abstract In the present investigation, a novel Schiff base ligand was synthesized through the condensation of benzaldehyde, o-hydroxyacetophenone, and 1,2-ethylenediamine using an ultrasonically assisted green chemical approach. The resulting ligand was subsequently employed as a capping agent for the synthesis of cadmium sulfide nanoparticles (CdS NPs), yielding Schiff base-functionalized CdS nanoparticles (L–CdS NPs). The synthesized Schiff base ligand and functionalized nanoparticles were comprehensively characterized by elemental analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–Vis, IR, 13 C and 1 H NMR, and HRMS techniques. XRD analysis confirmed the crystalline nature of CdS and revealed nanoscale crystallite dimensions, while the observed peak broadening was indicative of reduced particle size and the formation of a highly crystalline, phase-pure structure. Photoluminescence studies further demonstrated enhanced emission characteristics of the Schiff base-capped CdS nanoparticles compared with the uncapped CdS nanoparticles. These results indicate that Schiff base functionalization not only contributes to the stabilization of the CdS nanoparticle surface but also modulates its physicochemical and biological properties. Both the free Schiff base ligand and L–CdS NPs exhibited appreciable in vitro cytotoxicity against Dalton’s lymphoma ascites (DLA) cells, with the nanoparticle formulation displaying substantially enhanced cytotoxic efficacy. Consistent with these findings, in vivo studies demonstrated pronounced antitumor activity against both Ehrlich ascites carcinoma (EAC)-induced ascites and DLA-induced solid tumour models in Swiss albino female mice, underscoring the therapeutic potential of the Schiff base-functionalized CdS nanostructure as a multifunctional bioactive platform. The L–CdS NPs were further investigated for their biological potential, particularly antibacterial activity. Overall, the findings demonstrate that Schiff base capping provides an effective strategy for stabilizing CdS nanoparticles while enhancing their biological activity, highlighting their potential for future biomedical and nanotechnological applications.