doi:10.1038/nindia.2016.75 Published online 7 June 2016
By controlling a microdroplet reaction, researchers have gained new insights into the synthesis and growth of chitosan nanoparticles1. These insights may be useful for employing these nanoparticles as drug carriers and fluorescent diagnostic agents.
Current techniques for synthesizing nanoparticles use multiple reagents, are time consuming and produce toxic by-products. To remedy these shortcomings, the researchers explored using microdroplet reactions to produce chitosan nanoparticles by stopping the reactions at various times and monitoring nanoparticle nucleation and growth.
The scientists varied reaction parameters such as reactant concentration, pH and temperature, and then imaged the growth of the chitosan nanoparticles. Increasing the chitosan concentration, increased the number of nanoparticles, while decreasing the reaction temperature reduced their size.
In the initial few seconds, more nanoparticles formed at 4 degrees Celsius than at 27 and 35 degrees Celsius, irrespective of the chitosan concentration. The nucleation phase started during the first 3 seconds, and it was followed by a growth phase. Fully grown nanoparticles were observed after 10 seconds.
Besides providing critical insights into the ionic gelation process that helps form chitosan nanoparticles, these reactions could be used to scale up nanoparticle synthesis in on-chip droplet reactors.
“Since these nanoparticles can easily permeate cells, they can enhance the efficacies of drugs, enabling their doses and side effects to be reduced,” says lead researcher Dhananjay Bodas.