Work

Bio–Nano Interactions of Recombinant Cyanobacterial Metallothionein with Magnetic Nanoparticles for the Removal of Cadmium and Uranium

Year: 2025

Type: article

Abstract: Heavy metal pollution, as a result of anthropogenic activities, is a subject of concern and needs sustainable remedial measures. In this context, we synthesized a bio–nanocomposite comprising a metal-binding protein, metallothionein (NmtA), from a filamentous, heterocystous cyanobacterium, Anabaena sp. strain PCC 7120, immobilized in magnetic nanoparticles (MNPs) for removal of cadmium (Cd) and uranium (U). The recombinant NmtA, purified from E. coli, was immobilized onto citrate-functionalized Fe3O4 magnetic nanoparticles (CMNP-NmtA) by an EDC-NHS coupling reaction, which exhibited heavy metal sequestration features. TEM analysis revealed that CMNP-NmtA nanocomposites were roughly spherical with an average size of 9.3 nm, and the DLS analysis showed a number-weighted average size of 165.5 nm for the composites. A zeta potential of −25.8 mV indicated the stability of the nanosuspension (CMNP-NmtA) in an aqueous medium. The CMNP-NmtA nanocomposites showed high removal efficiency for Cd (∼90% from 10 μg/mL) and U (∼81% from 10 μg/mL) from aqueous solutions and demonstrated their easy separability using iron magnets. The maximum adsorptive capacities of the CMNP-NmtA nanoadsorbent, derived from the Langmuir isotherm, for Cd and U were found to be 21.43 and 43.32 μg/mg, respectively. Scanning electron microscopy (SEM) coupled with energy-dispersive X-ray (EDX) spectroscopy analysis confirmed the association of Cd and U with the nanocomposites following their exposure to corresponding metal solutions. X-ray photoelectron spectroscopy (XPS) studies confirmed the binding of Cd and U with CMNP-NmtA in the form of Cd(II) and U(VI), respectively. The findings of this study present the potential of bio–nanoformulation for the removal of not only soft heavy metals like Cd but also radionuclides like U from contaminated solutions, supported by its magnetically recoverable features.

Source: ACS Omega

DOI: 10.1021/acsomega.5c01248

Authors: T. V. Divya, Bijaideep Dutta, Kaustava Bhattacharyya, K. C. Barick, Celin Acharya

Institutions: Bhabha Atomic Research Centre, Homi Bhabha National Institute

Language: English

Topic: Adsorption and biosorption for pollutant removal

Subfield: Water Science and Technology

Field: Environmental Science

Domain: Physical Sciences

SDG: Clean water and sanitation

Open Access status: gold

Estimated APC paid: $1,935