A Facile Colorimetric and Spectrophotometric Method for Sensitive Determination of Metformin in Human Serum Based on Citrate-Capped Gold Nanoparticles: Central Composite Design Optimization

[Image: see text] For the determination of Metformin in human serum, a facile colorimetric and spectrophotometric sensor was designed based on citrate-capped gold nanoparticles (citrate-GNPs). In this probe, the addition of Metformin to GNP solution generates a naked-eye color change resulting from the aggregation of GNPs. Study of this color conversion and quantity analysis of analyte is operated by spectrophotometric instruments. The three factors pH, time, and GNP ratio were selected to examine their effects on sensing results and their values optimization. The optimization of parameters was done by means of central composite design and one-at-a-time methods. The sensing results proved the highly selective and sensitive performance of the sensor for Metformin in a linear range of 6.25–133.3 ppm with a detection limit of 1.79 ppm. The relative standard deviation (RSD) of the reported method is 2.53%.