Green synthesis of graphene quantum dots from Opuntia sp. extract and their application in phytic acid detection

Phytic acid and phytate anions are among the principal reserves of phosphorus. A few methods have been used for their detection, but these methods require harsh conditions. In this work, graphene quantum dots are successfully synthesized by Opuntia sp. extract through a pyrolysis microwave treatment. This green synthesis method allows us to controllably obtain nanostructures with excellent dispersion and a narrow size distribution to use for detecting phosphates and phytic acid and amplifying fluorescence quenching at pH = 8.8. Their application allows for a one-step turn-off system. The quenching percentage for phytic acid (PA) detection is 53%, and the quenching percentages are 26 and 21% for sodium phosphate monobasic (SPMB) and sodium phosphate dibasic (SPDB), respectively. The Stern-Volmer analysis shows that static and dynamic quenching mechanics contribute to phytic acid quenching.