Scalable Formation of Environmentally Benign Nanoparticles for Use As Delivery Vehicles of Active Ingredients

Authors: 
Conner, C., North Carolina State University
Velev, O. D., North Carolina State University
Our group has introduced a class of environmentally benign nanoparticles (EbNPs) for biotech applications (Nature Nanotechn. 10:817, 2015). These nanoparticles are made of biodegradable lignin and have low potential for nano-toxic impact. The lignin core nanoparticles are synthesized through flash nanoprecipitation, but until recently they were produced in mL-scale batches. We have developed a semi-continuous system featuring a recycle loop, making it possible to produce such nanoparticles in practical quantities for industrial applications. We investigate the role of each variable in our process to determine how to control the size of our EbNPs and the final concentration of the EbNP suspensions. By changing the concentration of lignin in solvent, we are able to efficiently control the final size of synthesized nanoparticles. Then, by altering the anti-solvent volume, we control the final NP concentration of the dispersion. With our semi-continuous system, we are now able to make liters of concentrated nanoparticle suspensions at a time. We discuss a few applications of our EbNPs, including their role as highly efficient antimicrobials and antifungals. EbNPs that serve as antimicrobials are created by infusing silver ions into the lignin core and are coated with a polyelectrolyte layer, enabling them to stick to bacteria. This formulation has the potential to decrease use of silver in consumer products and thus limits its eventual release into environment. We also investigate the application of the EbNPs on other biological surfaces, such as rose petals and human hair. We modify the lignin nanoparticles with a cationic biopolymer coating, chitosan, to make them adhere to these surfaces. The nanoparticles can be functionalized with active ingredients as needed for different applications.