The synthesis of metal nanoparticles and their applications is one of the most important areas of nanotechnology research. Metallic nanoparticles due to their distinctive properties such as size and shape, structural stability, and strong oxidation resistance have been employed in a variety of fields in recent years, including industry, biomedicine, electronics, and pharmaceutical release (de França Bettencourt et al., 2020, Loza et al., 2020). Platinum, silver, and gold nanoparticles have sparked significant interest due to their excellent biocompatibility and functional diversity in various fields such as biosensor design, solar cells, electro-catalysts, and catalysis of chemical processes (Almalki and Khalifa, 2020, Dutta et al., 2015, Fritea et al., 2021, Yaraki et al., 2022). Despite the numerous monometallic nanoparticle applications, one strategy for novel nanoparticle bio-synthesis is to combine different metals, which alter the atomic structure and physicochemical properties of nanoparticles, reducing their toxicity, and increasing their technological performance (Długosz et al., 2021, Loza et al., 2020).

The synthesis methods for metallic and bimetallic nanoparticles have a significant impact on their shape, final particle size, and applications. Typically, nanoparticles are synthesized utilizing physical and chemical processes such as hydrothermal, sol-gel, sonochemistry, micro-emulsion, and green synthesis, each with its own set of advantages and disadvantages (Fatemi et al., 2018, Rane et al., 2018). Due to the employment of cytotoxic chemical reducing agents to transform metal ions into nanoparticles, physical and chemical procedures have limited the use of manufactured nanoparticles in biological and biochemical research (Patil et al., 2022). In this direction, current research has focused on the use of living organisms such as bacteria, fungi, plant extracts, and yeasts for nanoparticle synthesis (Calvo et al., 2022). A bio-based technique has potential benefits over conventional synthetic approaches in terms of cost-effectiveness, non-toxicity, high environmental biocompatibility, safety, and improved physicochemical properties (Chandrakala et al., 2022, Vijayaram et al., 2023). Among biological hosts, the employment of bacterial microorganisms or biomass is more economic for the bio-synthesis of metal nanoparticles due to the availability of enzymes or proteins as reducing agents and facile and low-cost manufacturing (Das et al., 2017, Fatemi et al., 2018, Gahlawat and Choudhury, 2019). Therefore, the bacterial-mediated synthesis of platinum, silver, and gold nanoparticles has demonstrated the capacity of various bacteria to reduce metal salts into metal nanoparticles (Hammami and Alabdallah, 2021, Jeyaraj et al., 2019, Saeed et al., 2020).

Bio-synthesized nanoparticles are often affected by their formation environment and modified with stabilizing factors such as proteins and other simple functional groups. Small nanoparticles, in general, caused the death of bacteria by penetrating the cell membrane and causing interference in membrane processes (Yin et al., 2020). These advantages could lead to anti-cancer, anti-bacterial, and a variety of technological applications. In addition to their remarkable biological and physical features, their catalytic function may be considered as one of the most prominent uses. Chemical catalysts might be replaced by bio-synthesized nanoparticles due to their high activity in various chemical processes such as Gewald reaction, photochemical reactions, catalytic redox reactions such as chemiluminescence (CL), and so on (Macaskie et al., 2017, Vijayaram et al., 2023).

2-Aminothiophenes, which are widely used in industry, particularly in pharmacy and medicine, can be produced through the Gewald reaction (Kurmach et al., 2023). Therefore, it is needed to enhance the Gewald reaction using environmentally friendly catalysts in order to synthesize derivatives of 2-aminothiophene. Chromene and its derivatives, which are oxygen-containing heterocyclic compounds, are widely used in pigments, natural products, and cosmetics. They have also proven to be highly cytotoxic to human cancer cells (Liu et al., 2022, Patil et al., 2013). Considering the increasing focus on green routes in synthetic organic chemistry, it is imperative to replace conventional methods for chromene synthesis with environmentally safe photoredox catalysis via visible light as a cheap, simple, and non-toxic source of energy (Liu et al., 2022, Tiwari et al., 2016). In this regard, improving the synthesis of chromenes can be achieved by studying the photocatalytic ability of low-cost bio-synthesized nanoparticles with environmentally friendly organic solvents in the presence of visible light. Peroxyoxalate chemiluminescence (POCL) is a phenomenon in which excited, chemically produced molecules emit light. CL has recently been tested for use in biotechnology, industry, and medicine due to its superior emissions (Iranifam, 2016, Keat et al., 2015, Samuel et al., 2020, Zhang et al., 2019). Because CL is proportional to the concentration of the reactants, it has been used as an ultrasensitive approach for quantitative chemical analysis.

In this research, First, we use a green approach to synthesize Pt, Au, Ag, Au-Ag (alloy), and Au@Ag (core-shell) nanoparticles, and the influences of several factors (such as temperature and pH) on the synthesis, are examined. The nanoparticles are then analyzed with different methods. Second, the catalytic properties of nanoparticles in the Gewald reaction for the production of 2-aminothiophene derivatives by the mediation of a green color LED in a solvent-free condition are investigated. Third, the photocatalytic properties of PtNPs are studied. Forth, the Pt nanoparticles (PtNPs) is applied in POCL system in the presence of NFR as a novel fluorophore. The characteristic of the new POCL system, kinetic parameters and catalytic role of PtNPs are thoroughly explored. Finally, the anti-cancer characteristics of as-synthesized nanoparticles are examined and validated using MTT assays to measure the survival rate of MCF-7 (Michigan Cancer Foundation-7) cells in various nanoparticle concentrations.

The novelty of this research is introducing CKCr-6A and GFCr-4 bacterial strains for the biological synthesis of metal nanoparticles. These strains were isolated from samples contaminated with heavy metals from the chromite mine. The bacterial strains have the following properties: 1) are capable of producing a variety of extracellular reductase enzymes; hence, in addition to their enzymatic bioremediation functions, these strains can simply and economically synthesize a wide range of metallic and bimetallic nanoparticles. 2) Small-sized functionalized nanoparticles can be synthesized in the presence of these bacterial strains by adjusting the synthesis conditions. The small-size nanoparticles have a catalytic role in industrial processes and anti-cancer properties in biomedicine. Furthermore, the presence of functional groups on nanoparticles prevents the agglomeration of particles and makes them a suitable option for medical applications.