Nanotechnology is an interdisciplinary field with the highest expansion rate in medical applications. Nanoparticles significantly affect nanomedicine, including microfluidics, biosensors, tissue engineering, and drug delivery [1]. They are smaller and may communicate with multiple organelles and biological molecules, including proteins, RNA, and DNA, by crossing their cellular barriers [2]. Thus, the use of nanotechnology for drug delivery has successfully treated various diseases [3]. Cancer is one of the most lethal inherited diseases, resulting in a greater number of deaths [4]. Metal oxide nanomaterials have drawn much interest for cancer therapeutic drug distribution because of their biocompatibility, flexibility, affordability, and unique physical and chemical properties [5].

Plant-based products have significant properties such as low toxicity, enriched bioactive compounds, and biological abilities with macromolecular specificity. Therefore, plant-based products are a promising lead for discovering new medications [6]. However, because of their highly hydrophilic properties, the primary drawback of using plant-based drugs for the treatment of various diseases is their limited absorption in the human body. This problem can be resolved by encapsulating plant products in nanoparticles. Additionally, nanoparticles may improve the effectiveness and reliability of natural substances by focusing on distinct tissues or organs and emphasising prolonged release [7]. The National Cancer Institute states that injecting drugs with nanoparticles offers a spectacular, paradigm-shifting opportunity to accomplish outstanding cancer diagnostics and therapy research [8].

Zinc oxide nanoparticles (ZnO NPs) are widely used owing to their non-hazardous behaviour, outstanding photostability, and high binding energy [9]. Synthesis utilises various physical and chemical approaches, such as chemical precipitation, microemulsion, sol-gel, and hydrothermal synthesis [10]. The chemical precipitation method comprises chemical interactions of the raw ZnO precursors [11,12]. In the microemulsion method, water-in-oil microemulsions are water-based microdomains scattered across a continuous oil phase sustained by an emulsifier. These function as microreactors, where a co-precipitation method generates ZnO nanoparticles [13,14]. The sol-gel technique creates ZnO nanoparticles by dissolving the chemical precursor in ethanol or H2O, heating it, and agitating it to cause hydrolysis, which converts it into a gel [15,16]. The hydrothermal technique allows the synthesis of ZnO nanomaterials at temperatures ranging from ambient to extremely high temperatures [17,18]. In contrast, biological synthesis involves microbes, plant extracts, and enzymes, and is widely preferred owing to its low toxicity and cost-effectiveness. Plant extracts actively contribute to bioreduction, which converts metal ions into metal and metal oxide nanoparticles [19].

Previous reports have shown that ZnO NPs synthesized using the leaf extract of Mangifera indica exhibited significant antioxidant and anticancer properties against A549 cell lines [20]. Zinc oxide NPs produced from Moringa oleifera peel extract showed notable haemolytic, photocatalytic, antibacterial, and antifungal activities [19]. Zinc oxide nanoparticles synthesized using Limonium pruinosum showed considerable antibacterial and antioxidant activity and significant anticancer properties against the A-431 cell line [21]. Potential anticancer activity against the A549 cell line was exhibited by ZnO NPs synthesized from the leaf extract of Raphanus sativus var. Longipinnatus [22]. Apoptotic-mediated anticancer activity was observed in HeLa cell lines using ZnO nanoparticles synthesized from Solanum nigrum leaf extract [23]. ZnO nanoparticles from Xylaria arbuscula showed remarkable antioxidant, antibacterial, antidiabetic, anti-inflammatory, anticancer, wound healing, and photocatalytic activities [24].

Anodendron paniculatum or Anodendron parviflorum (Roxb.) (A. parviflorum) is a climber that belongs to the Apocynaceae family. Traditional Indian folk medicine uses the roots of this plant to treat vomiting and coughing. Furthermore, snake and centipede bites can be cured using the latex of A. parviflorum [25]. The aerial parts of A. parviflorum contain a novel triterpene ester named anopaniester, cycloartenol, and several compounds that significantly inhibit the MKN-7 and LU-1 cell lines [26]. Reports suggest that the green production of metal oxide and carbon nanocomposites produces novel nanocomposites that exhibit notable biological properties. The green synthesis of CuO/C nanocomposites with a carbon source such as sucrose demonstrated significant antifungal properties [27]. The C/CuO nanocomposites synthesized using the leaves of Aristolochia bracteolata demonstrated potent ovicidal and larvicidal activity [28]. However, there have been no reports on the synthesis of ZnO/C nanocomposites using a green approach.

The zinc oxide nanoparticles synthesis through green approach can progress using different methods, including magnetic stirrer [29,30], water bath or oil bath [31,32], microwave-assisted method [33,34], ultrasound-assisted method [35,36], UV-mediated synthesis [37] and LED assisted synthesis [38]. In earlier reports, microwave-assisted nanoparticle synthesis consistently produced smaller and narrower nanostructures with higher crystallisation levels and smaller sizes than conventional oil baths [39,40]. To date, the synthesis of ZnO NPs under LED light has not been reported. Researchers have discussed the use of different LED lights in the physical and chemical synthesis of silver NPs; however, more studies have yet to explore the use of LEDs in nanoparticle green synthesis [41]. Nanoparticles can be effectively synthesized using LEDs due to their faster synthesis, cost-effective, high photon efficiency, power stability and low power consumption [42].

A. parviflorum has been reported to have several therapeutic benefits in conventional medicine due to its various bioactive compounds. The different solvent extracts of A. parviflorum revealed various phytocompounds, including phenols, flavonoids, alkaloids, terpenoids, and saponins [26,43]. Plant phytoconstituents have the potential to act as stabilising and reducing agents as well as stimulating the synthesis of nanomaterials [44]. In this regard, we optimised and synthesized pristine ZnO NPs and ZnO/C novel nanocomposites using an ethanolic extract of Anodendron parviflorum via three different methods: microwave-assisted synthesis, blue-LED synthesis, and oil bath synthesis. The synthesized nanoparticle and nanocomposites were analyzed using UV–visible spectroscopy, FTIR, AFM, TGA, XRD, XPS, EDX, FE-SEM, zeta potential, and Raman analysis. It was subjected to antioxidant, biocompatibility studies (haemolytic and brine shrimp lethality assays), and anti-cancer activities against A549 and HeLa cell lines.