An antibody conjugated NH2-MIL-101(Fe) metal-organic framework based optical biosensor for sensitive detection of lead ions

The detection of heavy metals holds significant importance in environmental monitoring. This study reports the development of a fluorescent metal–organic framework (MOF), an amine-functionalized MIL-101(Fe), functionalized with monoclonal antibodies specific to Pb2+ ions for highly sensitive detection of lead ions using it as a fluorescent signal probe. The synthesized MOF displayed good water stability and biocompatibility due to the presence of amine groups for functionalization with antibodies. The addition of Pb2+ ions led to a significant drop in fluorescence of the developed bioprobe within a few minutes, thus demonstrating a rapid and highly selective turn-off fluorescent immunosensor. A reasonable limit of detection of 9.51 ppb has been achieved, and the immunosensor detected a linear range of 50–1000 ppb Pb2+ in water. In addition, the developed method was employed to detect Pb2+ spiked in the real environmental water samples with an acceptable recovery % of 92.0 %- 104.0 %. The technique ensures the determination of Pb2+ within permissible limits of WHO and EPA as recommended for drinking water samples.