Abstract
A new methodology involving the use of Bovine Serum Albumin (BSA) as a probe and liquid crystal (LC) as a signal reporter for the detection of heavy metal ions in water at neutral pH was developed. BSA acted as a multi-dentate ligand for the detection of multiple metal ions. The LC sensor was fabricated by immobilizing 3 µg mL−1 BSA solution on dimethyloctadecyl-[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP)-coated glass slides. In the absence of heavy metal ions, a dark optical image was observed, while in their presence, a dark optical image turned to bright. The optical response was characterized by using a polarized optical microscope (POM). The BSA based LC sensor selectively detected toxic metal ions as compared to s block metal ions and ammonium ions in water. Moreover, the limit of detection was found to be very low (i.e., 1 nM) for the developed new biosensor in comparison to reported biosensors.
Highlights
The term heavy metal ions is employed to any metallic element that has a relatively high density and is toxic or poisonous at low concentrations [1]
The optical results suggest that the greater surface coverage by Bovine Serum Albumin (BSA) might be due to the involvement of strong electrostatic, intermolecular and covalent interactions between the BSA active functional groups and modified DMOAP interfaces [22]
BSA optimization was confirmed from optical imaging and it was found that 3 μg mL−1 BSA has a detection limit for heavy metal ions that is as low as 1 nM
Summary
The term heavy metal ions is employed to any metallic element that has a relatively high density and is toxic or poisonous at low concentrations [1]. Reliable techniques for the detection and quantification of these heavy metal ions on the water surface and within the body fluids of an organism are very important for improving public health and environmental protection [8]. Common methods such as spectroscopy [9], colorimetry [9,10,11], potentiometry [12] and electrochemical techniques [13,14] are employed for these purposes. Despite the fact that these techniques are precise and accurate in identification of toxic metal ions, the major disadvantages associated with them include high cost, longer execution time and need of technically sound workers
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