Synthesis of silver nanoparticles in skim natural rubber latex at room temperature

• Skim natural rubber Latex contains large amount of components for AgNPs synthesis.
• Left-over ammonia and sugar in latex act as reducing agents in the synthesis.
• Proteins in latex acts as stabilizing agent.
• Rubber particles act as capping agent.
• The process is green because only Ag+ is needed to react at room temperature.

Silver nanoparticles (AgNPs) were synthesized in low cost skim natural rubber latex by adding silver nitrate as a source of silver ions. Left-over ammonia in latex was believed to form a complex with silver ions before reacting with the reducing agents which were glucose and other organic compounds in latex. Moreover, protein in latex could also control the growth of the particles by acting as a stabilizing agent. Many factors, which include ammonia content, d-glucose content and BSA protein content, were studied to clarify their effects in the synthesis. The emergence of AgNPs was checked with UV–visible spectrometer and electrical conductivity meter. Transmission electron microscope (TEM) was applied to study the particle morphology. The results showed that UV absorbance (ABS) and conductivity of the reacting suspension increased when ammonia content and d-glucose content increased, implying an increasing number or growth of particles. In contrast, ABS and conductivity decreased with increasing BSA content, showing that smaller particles were formed. The TEM images confirmed that the size of AgNPs in the none-added sample was 6–26 nm. The synthesized AgNPs could inhibit the growth of Escherichia coli and Staphylococcus aureus.