## 1 Introduction  
Over the past twenty years, silver nanoparticles (AgNPs) have become increasingly popular due to their special physical, chemical, and biological properties. It is characteristic that, depending on the surface to volume ratio, the properties of nanosilver change, and they have been exploited for different purposes [1, 2]. AgNPs offer promising prospects for a wide range of applications, such as antimicrobials against bacteria [3, 4, 5, 6, 7, 8, 9, 10, 11, 12], fungi [13, 14, 15, 16, 17, 10], and viruses [18, 19, 20, 21, 22, 23]. Silver nanoparticles can also be helpful in managing the ongoing pandemic of COVID-19 (Coronavirus Disease 2019) caused by the SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) [24, 25]. AgNPs have been tested as biomedical device coatings [12, 26, 27, 28], combating multidrug-resistant cancer [12, 29], drug-delivery carriers [12, 30], and imaging probes in ultrasensitive analysis [26, 31, 32, 33, 34]. They may also find applications in sensing [35, 36, 27, 31] and chemical catalysis [37, 38, 32, 35]. Due to the great interest of AgNPs, different synthetic methods have been developed, such as physical, chemical, and biological approaches [26, 40, 41]. Among them, chemical reduction is the most frequently used synthesis method of silver nanoparticles, with high productivity and low costs [39, 41]. In this approach, stable colloids in water or non-aqueous solvents can be obtained. Generally, synthesis of AgNPs in solution requires three particular components: metal precursors (silver nitrate, perchlorate, chloride, trifluoracetate or (PPh\({}_{3}\))AgNO\({}_{3}\)), reducers, and stabilizers [42]. Several reductants are commonly used for the preparation of the AgNPs: sodium borohydride, sodium citrate, glucose, \(N\),\(N\)-dimethylformamide, hydrazine, polyols, (e.g., ethylene glycol, diethylene glycol), formaldehyde [42]. One important factor is to apply capping agents to stabilize dispersive NPs, thus protect them against their agglomeration [41]. In general, the shape and size distribution of the synthesized nanoparticles are controlled by altering the method and conditions of the synthesis, reducing and stabilizing agents, their concentrations, and molar ratios [43]. Recently, different types of surfactants started to be used as stabilizing agents for AgNPs. We should mention that a proper stabilizer and/or reaction time is crucial for the obtaining of stable and small size Ag nanoparticles [44]. Dimeric quaternary alkylammonium salts, named by [PERSON] and [PERSON] as gemini, are modern type of surfactants [45]. These compounds consist of two long alkyl substituents and two cationic headgroups connected by a linker. The connector may have various structures: short, long, flexible, stiff, polar (e.g., functionalized by heteroatoms), and nonpolar (e.g., hydrocarbon chains or rings) [46; 47; 48; 49; 50]. Spacer and hydrophobic chain are very important units in gemini surfactant architecture. They are a keystone in the adsorption of dimeric surfactants on surfaces and interfaces, in creation of micelles of different shapes [48; 49; 51; 52; 53; 54]. Considering the structure of gemini surfactants, they exhibit a higher efficacy in contrast to monomeric (conventional) surfactants, such as decreased critical micelle concentration (CMC), greater ability to reduce surface tension, or promote antimicrobial activity [48; 55; 56; 57; 58]. From an ecological point of view, dimeric alkylammonium salts are considerably less toxic to marine organisms than quaternary ammonium salts [58; 59], and can be biodegradable [48; 60; 61; 62]. Considering the above properties, and the fact that the use of gemini surfactant provides the desired effect at a lower concentration in comparison to monomeric analogues, the use of dimeric alkylammonium salts is correlated with the greenolution idea in chemistry [63; 64].