Waste Derived Chlorogenic Acid Ag Nanozyme for Nanomolar Dopamine Sensing in Pharmaceutical Formulations

Abstract

Biosynthesized nanozymes are attractive for low cost dopamine (DA) sensing, yet most reported systems rely either on synthetic nanomaterials or poorly defined “green” extracts, which limits sustainability, reproducibility, and translational relevance. Here, we establish a waste to nanozyme platform that converts Musa balbisiana wine processing residues into chlorogenic acid capped silver nanoparticles (BK AgNPs) using an HPLC isolated CGA (chlorogenic acid) fraction as a chemically defined bioreductant and stabilizer. The resulting BK AgNPs display a plasmon band at 443 nm, a TEM core size of ~28 nm and a face centred cubic Ag lattice with high elemental purity. Engineered as peroxidase mimetic nanozymes, they efficiently catalyse H₂O₂ driven oxidation of TMB under mildly acidic conditions (pH 4.0, 35 °C), with steady state kinetics indicating strong affinity for both TMB and H₂O₂. Exploiting DA induced inhibition of this peroxidase like activity, we developed a simple colorimetric assay that affords a linear response from 20–200 nM and a detection limit of 42.51 nM, outperforming several recent nanozyme based DA platforms that operate in the 0.072–2.31 µM range. Zeta potential and DLS measurements reveal that DA adsorption neutralizes the CGA capped surface (–8.0 → –1.4 mV) and reorganizes aggregates (≈5.4 → 3.3 µm), directly linking signal suppression to surface charge modulation and colloidal restructuring. Validation using a commercial dopamine hydrochloride injection demonstrates nanomolar level sensing in a realistic pharmaceutical matrix, while explicitly quantifying matrix induced attenuation. Overall, this work introduces a chemically defined, wine waste derived nanozyme platform that couples green synthesis with mechanistically understood, pharmaceutically relevant DA detection.