In summary, proof-of-concept large-area Ag-Gum Arabic nanocluster-based SERS substrates were prepared using an electrochemical deposition method. This fabrication method was environmental friendly, cost effective, simple, and rapid. These SERS substrates could detect 2,4-D pesticide in water directly without sample pre-treatment with a limit of detection 1 pM achieved. Detection of 2,4-D in relevant matrixes such as mineral or river water was also achieved down to 0.15 nM. Compared to previous 2,4-D detection study by SERS, see SI table , the present SERS platform was faster and was able to detect 2,4-D down to 1 pM. This was around 50 times lower than the lowest detection ability and three times lower than the calculated LOD reported by a previous SERS study. Work is now on-going to improve the SERS sensor performance using molecular imprint techniques to optimize trapping of target analytes.