Inter American University of PR, Ponce Campus
Presenters: Esther M. Irizarry Quintana & Stephanie Anne Pérez Huke, IAUPR, Ponce Campus
Project: Sustainable Nanomaterials from Avocado Waste: Chemical Design and Antimicrobial Performance of Carbon Dots@Gold Nanocomposites
Description of the project: This project focuses on the sustainable synthesis of carbon dots (CDs) from avocado peel waste, addressing both the environmental impact of agricultural byproducts and the growing need for alternative antimicrobial strategies. By converting biomass into functional nanomaterials, the project demonstrates how green chemistry can support innovation in biomedical and environmental applications.
Carbon dots were synthesized using a green‑route method and subsequently functionalized with gold nanoparticles (AuNPs) through electrostatic interactions to form Au–CD nanostructures. The materials were characterized using UV–Vis spectroscopy, fluorescence spectroscopy, FTIR, dynamic light scattering (DLS), and scanning electron microscopy (SEM) to evaluate their optical properties, surface chemistry, size distribution, and morphology. Antimicrobial activity was assessed using a diffusion‑based assay against Escherichia coli and Bacillus subtilis.
The avocado‑derived CDs showed a 77% recovery, strong blue fluorescence (~460 nm), oxygen‑containing surface groups, and a median particle size of ~78 nm. In antimicrobial assays, CDs produced measurable inhibition zones against E. coli (up to 10.33 mm), demonstrating preliminary antibacterial potential. No inhibition was observed for B. subtilis, and AuNPs and Au–CDs did not show activity under the tested conditions. These outcomes provided valuable insights into how surface chemistry and synthesis parameters influence biological performance.
Lessons learned include the importance of incorporating proper control groups, optimizing reaction conditions, and refining antimicrobial testing protocols to improve reproducibility and interpretability. Overall, the project highlights the feasibility of producing low‑cost, sustainable nanomaterials from agricultural waste and their potential for future applications in biosensing, antimicrobial development, and drug delivery.
Biographies:
Esther Irizarry Quintana, born and raised in Ponce, Puerto Rico, is an undergraduate student at the Inter American University of Puerto Rico, Ponce Campus. She is currently engaged in green route nanomaterial development research, gaining hands‑on experience in sustainable scientific innovation. Esther has also participated in research at Ponce Health Sciences University, strengthening her foundation in scientific inquiry. Dedicated and motivated, she continues to expand her skills as she works toward her long‑term goal of pursuing a career in medicine and contributing to the well‑being of her community.
Stephanie Anne Pérez Huke was born in San Juan, Puerto Rico, on June 8, 2005. She began her studies at Colegio Sagrado Corazón de Jesús, where her 7th and 8th grade teacher, Mrs. Carmen Cruz, inspired her passion for science. She continued her education at University Gardens High School, specializing in science and mathematics. Her growing love for chemistry led her to pursue a degree in Applied Chemistry with a sub‑concentration in Biochemistry at the Inter American University of Puerto Rico, Ponce Campus. Stephanie is actively involved in green‑route nanomaterial research and aims to become a skincare and makeup product developer.