Due to the global threat of resistant bacteria, food safety, economic growth, and human and animal health are all at risk (Man et al. 2019; Puvača et al. 2021). Additionally, bacteria significantly contribute to persistent and recurring infections because of their propensity to create biofilms, which shield them from the host's immune system, antibiotics, and disinfectants (Singh et al. 2018; Nassima et al. 2019). In today's world, it is essential to have an efficient and advanced plan for managing and treating drug-resistant microorganisms (Swolana et al. 2020). Similarly, an unfavorable ecological shift is accompanied by untreated industrial and domestic effluents being discharged into the ecosystem(Natasha et al. 2020). The waste dye molecules significantly negatively impact humans, wildlife, and vegetation. As a result, organic dye effluents are now recognized as a significant threat to aquatic environments (Iqbal et al. 2020; Ahmad et al. 2022). Organic dyes are the most hazardous of all the contaminants released into our environment. The primary contaminants in industrial effluent are dyes because of their color (Javed et al. 2021; Sher et al. 2021a). The biological breakdown of dye molecules is exceedingly difficult because they are tenacious compounds. Due to their toxicity, commercial significance, and environmental effects, dyes have been the subject of extensive research (Qamar et al. 2022b). As a result, pathogens and organic contaminants must be removed and detoxified from water bodies more urgently than other pollutants. Different remediation techniques, including chemical, physiochemical, and biological treatments, have so far been suggested. However, each has its pros and cons compared to the others(Sher et al. 2021a; Javed et al. 2023).
These colored pollutants are difficult to remove using traditional methods (such as adsorption, coagulation, flocculation, biodegradation, and so on), and all of these procedures are expensive and require additional planning to remove the byproducts. Alternatively, photocatalytic degradation of hazardous dyes into harmless chemicals is the preferred method for reducing their environmental impact. Developing an effective and long-term solution for disposing of harmful dyes and pathogens in wastewater streams is paramount. Recent advances in nanotechnology have enabled the use of nanoparticles as biological agents for suppressing bacteria and as catalysts for degrading toxic pollutants. Materials at the nanoscale are the focus of nanoscience, which has applications in many different areas, including medicine, engineering, forensics, agriculture, cosmetics, and even orthodontics (Cullen et al. 2020). Its broad application in applied sciences, one of the fastest-growing fields of scientific research, and technological advancements pique the interest of researchers (Irshad et al. 2021; Sher et al. 2021a; Chakravarty et al. 2022).
Nanoparticles made of metals such as silver, gold, platinum, nickel, manganese, titanium, and zinc exhibit non-toxicity, antibacterial activity, and catalytic activity. The unique surface plasmon resonance (SPR) properties of gold nanoparticles (AuNPs) make them highly suitable for use in biological fields. They are also easy to produce, can be adjusted in size, and are multifunctional. Furthermore, their properties are well-established. There are many different approaches to synthesis, including chemical and physical techniques; however, it is unfortunate that they all negatively affect the surrounding environment(Lee et al. 2020; Hashmi et al. 2021). As a result, there is a pressing need to produce metal oxide NPs that are harmless to the environment through simple techniques and plant extracts and diverse biological species(Rasheed and Meera 2016). In vitro, the green synthesis of NPs is becoming increasingly popular due to its low environmental impact, low production costs, and high efficiency(Soni et al. 2018). This method is easy, rapid, and only requires one step and is suitable for production on a commercial scale. This technique involves converting metal salts into particles and stabilizing them with the use of a biological templates. Metal and metal oxide NPs offer good chemical, physical, and biological capabilities against bacteria, fungus, and viruses due to their high surface area, composition, and shape (Qamar et al. 2021; Singh et al. 2021).
There are numerous methods for producing metal nanoparticles, including chemical and biological processes involving microorganisms and plants. (Singh 2022). Due to their extensive surface area, gold nanoparticles (Au NPs) have unique electrical, magnetic, and catalytic properties and vast biological applications (Chen et al. 2022; Carrapiço et al. 2023; Mitri et al. 2023). Au NPs are adaptable and resourceful and can be modified into various shapes depending on the need to switch from one task to another (Manjubaashini and Thangadurai 2023). It becomes a strong competitor for silver. These NPs can effectively attack all types of bacteria and viruses compared to silver and other metals and are less hazardous and toxic to the environment when compared to other chemically synthesized nanoparticles (Timoszyk and Grochowalska 2022). Because of their resistance to surface oxidation, stability, flexible surface characteristics, and low cytotoxicity, Au NPs are excellent for nanotechnologies such as drug delivery (Patel et al. 2022). Grewia asiatica known as phalsa in lower Punjab (Pakistan) is rich in essential nutrients. In the current study Au NPs were produced using Grewia asiatica (locally called phalsa) leaf extract. There have been no studies regarding gold nanoparticle synthesized from this locally occurring phalsa. It is used for instant cooling the body in summer, maintaining electrolyte balance and soothing joint aches, and effectively managing seasonal and chronic conditions(Swain et al. 2023). It has a high level of vitamin C, minerals, proteins, phenolics, flavonoids, tannins and anthocyanins. It seeds fruit pulp highly rich in phytochemicals is used to treat different diseases and effective in improving respiratory and cardiac functioning. Their fruit has anticancer, antioxidant, and anti-hyperglycemic characteristics, while the stem bark has analgesic and anti-inflammatory effects(Ranjan et al. 2022). Their leaves have antibacterial, anticancer, and antiemetic properties. Hence, the current work is highly motivated to synthesize gold nanoparticles of the smallest possible size using leaf extract of Grewia asiatica (GALE) and to explore the photocatalytic dye degradation, antioxidant and biofilm inhibition properties of synthesized nanoparticles (GAAuNPs).