Highly selective sub-micromolar level colorimetric sensor for lanthanum detection based on l-tyrosine functionalized silver nanoparticles

•l-Tyrosine based silver nanoparticles (TRR-AgNPs) were synthesized by simple method.•TYR-AgNPs were applied as colorimetric sensor for trace level detection of La3+.•The developed La3+ sensor was extremely sensitive, selective and economical.•The developed sensor was applied to detect La3+ in rock and tap water samples.•The sensor could be extended for low level La3+ in other samples of interest.