Biosynthesis of gold nanoparticles using leaf extract of Salvadora persica and its role in boosting urease performance via immobilization

Abstract

Gold nanoparticles (AuNPs) have attracted attention in research because of their unique properties and opportunities for various applications. Immobilization is one of the major applications which take advantage of the AuNPs properties as they can be easily modified. Present work deals with the green synthesis of cysteine capped gold nanoparticles (Cys-AuNPs) by using Salvadora persica leaf extract. UV–Vis spectrophotometry, Transmission Electron Microscopy (TEM)¸ Fourier Transform Infrared Spectroscopy (FTIR), and X-Ray Diffraction Spectroscopy (XRD) were utilized to characterize the Cys-AuNPs. Further, urease was purified from Cajanus cajan urease by using ion exchange and gel filtration chromatography and its immobilization on Cys-AuNPs was carried out using glutaraldehyde as a cross-linker. Successful immobilization was confirmed by TEM and FTIR. Results showed that immobilization efficiency (IE) was 79% with enzyme loading of 84.37% and optimum pH and temperature for immobilized urease was 8.0 and 70 °C, respectively. Furthermore, immobilized urease was reusable upto 10 continuous cycles and can be stored up to 35 days with the retention of 50% residual activity. Enhanced properties of urease loaded Cys-AuNPs make it a suitable candidate for urea detection in clinical samples.