Adwaita S R Nair, Kunal Dhankhar, Deepika Singh, Arup Samanta, Saugata Hazra
Abstract: With the increasing mortality attributed to antibiotic resistance, the development of a rapid and early detection biosensor for beta-lactamase enzyme identification has become imperative. The exceptional optical and electromagnetic characteristics of gold nanoparticles have rendered them as a prime candidate for biosensing applications. This research seeks to establish a foundation for the nanosensor development by investigating intricate interaction between gold nanoparticles and the beta-lactamase enzyme, focusing on functional and conformational dynamics following conjugation. UV-visible spectroscopy has been employed to examine the stability of bioconjugates and influence of pH on their conformational state by observing changes in the localized surface resonance plasmon band (LSRP). The minor red shift of the LSPR peak following beta-lactamase conjugation confirms protein conjugation and indicates the absence of gold nanoparticle aggregation due to the protein. The fluorescence quenching of tryptophan residues in beta-lactamase, in the presence of gold nanoparticles, is utilized to ascertain the binding of protein onto the surface. Circular dichroism spectroscopy further provided insight into the structural integrity of bioconjugate. Intact α-helix and beta-sheet peak in CD spectra confirmed that the interaction of gold nanoparticle surface did not cause unfolding or denaturation of protein. These complementary biophysical measurements, when combined, create a stable, non-denaturing conjugation system that produces strong optical signatures while keeping the structure of β-lactamase intact. This research provides essential insights into the interaction between beta-lactamase and gold nanoparticles, facilitating the advancement of sophisticated nanosensors that may be utilized in early pathogen detection and the monitoring of antimicrobial resistance.
Keywords: Gold nanoparticle, Beta-lactamase, Antibiotic resistance, Bioconjugate, FTIR
Date Published: November 27, 2025 DOI: 10.11159/jbeb.2025.012
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