Blackstrap molasses as a source of bioactive compounds for the green synthesis of nanoparticles

By-products from the sugar industry (e.g., blackstrap molasses) can be a source of bioactive compounds (e.g., phenolics) known to have antimicrobial, antioxidant, anticancer, and anti-inflammatory properties. These bioactive molecules can be used in the green synthesis of metal nanoparticles. Metal nanoparticles have gathered attention because of their novel physico-chemical properties and potential biological applications (e.g., biocides, fungicides, pesticides, targeted drug and gene delivery, biosensing, medical implants, and plant biostimulants). Gold, silver, iron, and copper nanoparticles are of particular interest as they can be easy to operate and are cost effective, and biocompatible, and their biological activities can be enhanced by surface modifications. In this study, the reducing potential of the phenolic compounds in molasses was investigated for the synthesis of silver nanoparticles without the external addition of reducing agents. The reddish color formation and peak appearance at 420 nm were indications of the successful synthesis of the silver nanoparticles. The synthesized nanoparticles and reducing biomolecules were further characterized by microscopy (SEM, TEM, EDS) and spectroscopy (FTIR) techniques indicating nanoparticles of spherical shape and with particle sizes ranging from 15 nm–45 nm. Their antimicrobial activity was evaluated against several Gram-positive and Gram-negative bacteria. The synthesized nanoparticles showed a biocidal effect, further confirmed by microscopy techniques. It appears that the nanoparticles are interacting with the cell surface of bacteria, penetrating the cell and also causing the disruption of intracellular organelles.