Background: Lysozyme level in body fluids is a significant indicator of various diseases.
Cheap and simple colorimetric detection of lysozyme, in biological sample, by gold and silver
nanoparticles is a field of interest of nanoparticle research for more than a decade.
Objective: We report here an attempt to improve the sensitivity part of the colorimetric lysozyme
detection process by using citrate capped gold-silver core-shell nanoparticles without any functionalization.
Methods: Performance of gold-silver core-shell nanoparticles in determining of lysozyme concentration
in water is done using colorimetric/spectroscopic technique. Gold nanoparticles, silver nanoparticles
and mixed colloidal suspension of gold and silver nanoparticles, for comparison have
also been studied. Selectivity study has been performed through spectroscopic analysis, red-greenblue
colour component analysis and fractal dimension analysis of the nanoparticles interacted with
several low and high isoelectric point proteins.
Results: Gold-silver core-shell nanoparticles showed higher sensitivity for a wider range of lysozyme
concentration compared to gold and silver nanoparticles prepared by us or reported in literature.
Gold nanoparticles showed higher sensitivity compared to the core-shell nanoparticles, but
for a narrow concentration range of lysozyme. For silver nanoparticles and the mixed nanoparticle
system, both sensitivity and range of determination of lysozyme concentration were much smaller
compared to the core-shell nanoparticles. Core-shell nanoparticles showed better selectivity compared
to gold nanoparticles in identifying aquatic solution of lysozyme from that of other proteins.
Conclusion: Gold-silver core-shell nanoparticles have higher sensitivity in determining wide range
of lysozyme concentration in water compared to gold and silver nanoparticles reported in literature.