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Corn cob silica as an antibacterial support for silver nanoparticles: efficacy on Escherichia coli and Listeria monocytogenes

Shim, Jaehong, Mazumder, Payal, Kumar, Manish
Environmental monitoring and assessment 2018 v.190 no.10 pp. 583
Escherichia coli, Gram-positive bacteria, Listeria monocytogenes, cell walls, composite materials, corn cobs, nanoparticles, nanosilver, recycled materials, silica, silver, transmission electron microscopes, transmission electron microscopy, wastes
There is great potential to combine bioresource and recycled materials with nanotechnology for industrial and environmental applications. In a novel approach, silver (Ag) nanoparticles (Ag NPs) were imbedded on amine-functionalized silica obtained from corn cob (ACCS) to produce a composite material that can be used to inactivate bacteria. Transmission electron microscope (TEM) images show near-uniform ACCS particles (34.7 ± 8.6 nm diameter), with Ag NPs (5–10 nm diameter) homogenously dispersed on the surfaces. The potential of ACCS-Ag NPs to rapidly inactivate gram-negative Escherichia coli ATCC 8739 and gram-positive Listeria monocytogenes was investigated. A four-log (> 99.99%) inactivation of the E. coli was achieved within 30 min with 4 mg of ACCS-Ag NPs in a 40-mL PBS suspension (1 × 10⁵ CFU/mL). Extended exposure of ACCS-Ag NP may be required to inactivate L. monocytogenes, suggesting the ACCS-Ag NP composite will be less practical for gram-positive bacteria due to thick cell wall and alternative formulations may need to be developed. Result shows that the potential of corn cob silica as an alternative, eco-friendly support matrix for applications such as bacterial inactivation. The Ag-imbedded, amine-functionalized corn cob silica demonstrates how bio-waste can be combined with nanotechnology to produce useful materials.