colorimetric determination of captopril using mercaptopropionic acid functionalized silver nanoparticles

Abstract: captopril (cpt) as an angiotensin-converting enzyme widely used in the treatment of high blood pressure, coronary artery disease, congestive heart failure. this drug is considered as a drug of choice in the treatment of hypertension due to its effectiveness and low toxicity. it is useful for patients who are chronically ill and need long-term medication. thus, it is necessary to develop a facile and sensitive method for monitoring of cpt. up to now, some analytical methods including high performance liquid chromatography, voltammetry, surface-enhanced raman scattering and chemiluminescence were used for the determination of cpt. in recent years, silver nanoparticles (agnps) as colorimetric sensors have drawn extensive attention due to unique optical, low cost, simplicity, sensitivity and physico-chemical properties. the mechanism of measurement is based on change in surface plasmon resonance spectra of agnps. thus, in the present work, a simple, rapid, sensitive and cost-effectiveness colorimetric method based on mercaptopropionic acid functionalized silver nanoparticles was developed for detection of cpt. after addition of cpt, the absorbance intensity was reduced probably due to the aggregation of silver nanoparticles. to increase the sensitivity, the experimental factor affecting the absorbance such as ph, reaction time, temperature and salt addition were optimized. under the optimal conditions, the calibration curve was linear in the range of 0.1 - 1 mm of cpt and limit of detection (lod) was 0.03 mm.