Biofilm is a complicated three-dimensional accumulation of organized microorganisms in a self-produced extracellular polymeric matrix (EPM), a complex biochemical mixture of polysaccharides, proteins, glycoproteins, nucleic acids and lipids. These bacterial associations are stable, stress-resistant, and difficult to eradicate especially when drug-resistant bacteria are involved [1]. Different species of bacteria like Bacillus subtilis, Acinetobacter baumannii, Vibrio cholerae, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Lactococcus mutans among others can form the biofilm. Various surfaces, such as pipes, medical equipment, and naturally occurring surfaces like rocks in aquatic environments, can develop biofilms [2]. Biofilm-forming bacteria are resistant to conventional antimicrobial therapies due to the inability of the antimicrobial to penetrate the biofilm, evolution of complex drug resistance properties, and biofilm-mediated inactivation or modification of antimicrobial enzymes [2]. So, there is an urgent need to develop new mechanisms that control, inhibit or deteriorate the biofilm formation. One of the potentially successful strategies to combat the threat of antibiotic resistance may be transitioning from standard therapy to a high-tech method of using nanomaterials [3].

The study of nanomaterials has emerged as a promising multidisciplinary research area in recent times due to their exceptional properties and advanced applications in almost every domain of life [4]. Nanoparticles (NPs), ranging in size from 1 to 100 nm, find wide applications in various industries including food, pharmaceutical, energy industries, biotechnology and biomedicine owing to their small particle size, large surface areas, excellent thermal properties and phenomenal electrical conductivity. Among the NPs, metal oxide NPs such as TiO2, Fe3O4, ZnO, CuO and some mixed metal oxides have been in attention receiving attention over the past few decades in a vast diversity of biomedical applications [5]. The studies reported that CuO NPs provoked high interest in the scientific community because of their significant success in being used for drug delivery, treating chronic disease and for its ability to treat bacterial infections in wounded tissues [3].

Copper oxide NPs exhibit a monoclinic crystal structure and are characterized as a p-type semiconductor, featuring a relatively narrow bandgap of 1.7 eV. The distinctive properties of copper oxide nanoparticles contribute to a broad spectrum of applications [4]. Notably, in the biomedical field, these nanoparticles find use in antimicrobial, antibiotic, antioxidant, drug delivery, and anticancer applications. Beyond the biomedical sector, copper oxide NPs hold significance in various industries such as textiles. The diverse range of applications underscores the versatility and relevance of copper oxide nanoparticles across multiple domains [6].

Various preparative routes (including physical, chemical and electrochemical) have been reported in the academic literature for the formation of NPs. However, these commonly utilized methods suffer many drawbacks of the utilization of noxious chemicals, solvents, and reagents as well as the production of harmful by-products which are toxic for both living organisms and the environment, usage of high energy, employment of expensive types of equipment and maintenance of extreme conditions [7]. Due to these aforementioned reasons, now the focus for the synthesis has been shifted towards biochemical fabrication which uses environment-friendly natural extracts of biomass (plants, fungi, bacteria, and algae) as an alternative to hazardous chemicals used in conventional approaches [4].

Recently, green synthesis methodologies have attracted more attention in the scientific community for the production of efficient ways of NPs synthesis. Among the investigated green approaches, the bio-active compounds/phytochemicals present in the natural plant parts (including roots, shoots, leaves, flowers, fruits, and gums, etc.) for the fabrication and stabilization of NPs is the most common method [5]. Tragacanth gum (TG) (locally known as gond katira) is a special exudate produced as a result of an incision in the bark of Astragalus gummifer [8]. This viscous, odorless, tasteless, water-soluble natural gum possesses a broad range of biopolymers containing proteins, polysaccharides, and branched, heterogeneous carbohydrates (mannose, arabinose, rhamnose, and galactose) etc. [8,9]. The non-toxic, non-polluting, recyclable, sustainable, eco-friendly, widely available, biocompatible, and good water-binding nature of TG makes it an excellent material for the synthesis of the NPs [10]. The phytochemical profiling revealed that the plant contains several secondary metabolites including tannins, flavonoids, alkaloids, gum, mucilage and quercetin that act as stabilizing and reducing/oxidizing agents for the fabrication of NPs [11]. Moreover, the polysaccharides present in the gum have some potential biological properties including antimicrobial, antioxidant, anticoagulant, wound healing, hypocholesterolemic, antiviral, anti-inflammatory, larvicidal, DNA repair and antitumor properties [12].

Nanoparticles prepared through an environmentally friendly approach (green synthesis or green chemistry-based NPs) are safer, cost-effective and have diverse applications. They can be utilized in various fields such as making electrospun fibers, environmental cleanup (bioremediation), biocatalysis, biosensors, creating metal-hydrogel coordination complexes and biomedical purposes. Plant gums possess several advantages, including their widespread availability, structural variety, and favourable properties as sustainable bio-based materials. Notably, plant gums offer remarkable traits such as renewability, compatibility with living organisms, ability to break down naturally, lack of toxicity, and ease of modification through chemical processes. These qualities make plant gums suitable for safer and more environmentally friendly production and stabilization of nanoparticles [13]. This research aimed to synthesize TG based copper oxide nanoparticles and evaluate their biochemical and photocatalytic potential.