Rapid synthesis of highly stable silver nanoparticles and its application for colourimetric sensing of cysteine

Abstract

A modified green approach for the synthesis of stable silver nanoparticles (AgNPs) using tea leaf extract is described. The method involves the reduction of silver salt by the polyphenols present in the green tea leaf extract and requires no additional capping/stabilising agents. Compared to other biogenic methods for the synthesis of AgNPs, the uniqueness of the approach described here lies in its simplicity, low-cost, and rapid synthesis rate; the reaction being completed within 10À15 min at room temperature. The reaction was carried out in alkaline medium without stirring and heating, and requires no special cleaning or drying of the glassware used. The synthesised AgNPs were characterised by UVÀVis spectroscopy and transmission electron microscopy (TEM). The results showed that AgNPs with a strong surface plasmon resonance peak around 410 nm and particle size in the 5À30 nm range were prepared. The synthesised AgNPs show excellent chemical stability for more than six months in aqueous solution. Additionally, we showed that the as-synthesised AgNPs can be used as highly selective colorimetric and optical sensors for the detection of cysteine. Thus, with a simple synthesis strategy, and enhanced stability, these green-tea-functionalised AgNPs have the potential for further applications as biosensors and antimicrobial agents.

Antibacterial potential of silver nanoparticles biosynthesised using Canarium ovatum leaves extract

“…However as the yield of AgNPs increases, aggregation is likely to occur due to increase in the collision frequency of nanoparticles [16]. Earlier reports have also suggested that plant extract based synthesis of AgNPs requires longer time and highlighted it as one of the major limitation [2]. While, in the studies conducted by Shameli et al , [17] the reaction time required for AgNPs synthesis was 1 h. Similarly, Murgan et al [18] working with Acacia leucopholea took 1 h and 10 min at 90°C for AgNPs synthesis.…”

“…Metallic nanoparticles have found application in a plethora of fields that includes photonics, catalysis, bio‐imaging, environment remediation and drug delivery [1, 2]. Amongst metallic nanoparticles, silver nanoparticles (AgNPs) have emerged as one of the major potential candidates owing to their ease of synthesis, stability, biocompatibility and low toxicity [3].…”

Detection of helminth ova genera using in-situ biosynthesis of gold nanoparticles

“…Gold nanoparticles (AuNPs) provide excellent platforms for the development of colorimetric biosensors as they can be easily functionalised displaying different colours depending on their size, shape and state of aggregation [12]. The conventional method for the synthesis of AuNPs involves the reduction of gold ions by reducing agents such as alkanethiols and alkylamines, or polymeric materials such as polyvinyl alcohol and gelatin to stabilise the AuNPs from aggregation [13]. However the use of capping agents for stabilisation and toxic chemicals for reductions may result in the formation of hazardous by-products, adversely affecting their use in diagnostics [14].…”

High Variability in Silver Particle Characteristics, Silver Concentrations, and Production Batches of Commercially Available Products Indicates the Need for a More Rigorous Approach

“…Using a simple dilution, the observed color of particles with the same size and shape can change from, for example, dark orange to bright yellow. Moreover, λ max will not change by dilution, but a decrease in the absorbance at this λ max will be observed [51,52].…”