Flora Maitim Yrad

Title : Modified synthesis of dextrin-capped gold nanoparticles and its chemistry

Abstract:

Dextrin methodology is an aqueous alkaline chemical process for gold nanoparticle (AuNP) synthesis. Although dextrin-capped AuNPs reportedly demonstrate versatility in some biosensing applications, their synthesis takes 8 long hours of reaction.  A modified method is hereby described that simplified the procedure, equipment, and reduced the reaction time to only one hour. The key features of the modified method are the reversal of the addition of reagents in the original dextrin protocol and the increase of reaction temperature. Optimum synthesis was achieved by sequential neutralization of 50 mL of 2 mM HAuCl₄ with 0.5 mL of 10% Na₂CO₃ and alkaline reduction using selected volumes of 25 g/L dextrin. The AuNPs produced were monodispersed based on dynamic light scattering (DLS) measurements. The surface plasmon resonance band ranged from 517 to 520 nm indicating spherically shaped AuNPs. High resolution transmission electron microscopy (HRTEM) further confirmed the spherical shape with average sizes from 7.3 ± 1.1 to 18.9 ± 1.5 nm, depending on the volume of dextrin. Chemical reactions are hereby proposed to explain the chemistry of AuNP formation based on the alkaline reduction of HAuCl₄ with dextrin as the reducing agent.

Audience take-away:

• The audience will learn an alternative method of producing dextrin-capped gold nanoparticles.
• The modified method that will be described provides a simpler protocol, shorter reaction time, and less expensive equipment.
• Chemical reactions are proposed to explain the chemistry of the formation of dextrin-capped AuNPs.

Biography:

Dr. Flora M. Yrad studied Chemistry at Silliman University and the University of San Carlos, Philippines. She conducted her dissertation research at the Nano-Biosensors Lab, Department of Biosystems and Agricultural Engineering, Michigan State University, USA funded by the United States Agency for International Development (USAID) Advanced Research Scholarship and Silliman Faculty Development Committee (FADECO) Doctoral Scholarship. She had published her works on modified synthesis of dextrincapped gold nanoparticles and dengue RNA detection using lateral flow biosensor. She graduated in 2019 with a PhD in Chemistry. She obtained the position of an Associate Professor at Silliman University, Dumaguete City, Philippines.