Nanoporous solid-state membranes modified with multi-wall carbon nanotubes with anti-biofouling property

Ameneh Alizadeh1 Department of Biotechnology, Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan 8174673441, Iran, [email protected]

Amir Razmjou1 Department of Biotechnology, Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan 8174673441, Iran, [email protected];2 UNESCO Centre for Membrane Science and Technology, School of Chemical Science and Engineering, University of New South Wales, Sydney 2052, NSW, Australia, [email protected]Correspondence[email protected]

Mehrorang Ghaedi3 Department of Chemistry, Yasouj University, Yasouj 75918-74831, Iran, [email protected]Correspondence[email protected]

Ramin Jannesar4 Department of Pathology, Yasuj University of Medical Sciences, Yasuj 7591741417, Iran;5 Department of Biotechnology and Microbial Nanotechnology, Dena Pathobiology Laboratory, Yasuj 7591774414, Iran

Abstract

Purpose

Nanoporous membranes have been employing more than before in applications such as biomedical due to nanometer hexagonal pores array. Biofouling is one of the important problems in these applications that used nanoporous membranes and are in close contact with microorganisms. Surface modification of the membrane is one way to prevent biofilm formation; therefore, the membrane made in this work is modified with carbon nanotubes.

Methods

In this work, nanoporous solid-state membrane (NSSM) was made by a two-step anodization method, and then modified with carbon nanotubes (NSSM-multi-wall carbon nanotubes [MWCNT]) by a simple chemical reaction. Techniques such as atomic force microscopy (AFM), energy dispersive X-ray (EDAX), field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR), contact angle (CA), surface free energy (SFE), protein adsorption, flow cytometry, and MTT assay were used for membrane characterization.

Results

The BSA protein adsorption capacity reduced from 992.54 to 97.24 (μg mL⁻¹ cm⁻²) after modification. The findings of flow cytometry and MTT assay confirmed that the number of dead bacteria was higher on the NSSM-MWCNT surface than that of control. Adsorption models of Freundlich and Langmuir and kinetics models were studied to understand the governing mechanism by which bacteria migrate to the membrane surface.

Conclusion

The cell viability of absorbed bacteria on the NSSM-MWCNT was disrupted in direct physical contact with carbon nanotubes. Then, the dead bacteria were desorbed from the surface of the hydrophilic membrane. The results of this research showed that NSSM-MWCNT containing carbon nanotubes have significant antimicrobial and self-cleaning property that can be used in many biomedical devices without facing the eminent problem of biofouling.

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Supplementary material

Figure S1 The general schematic diagram of the fabrication and modification process of membranes.

Abbreviations: MWCNT, multi-walled carbon nanotube; NSSM, nanoporous solid-state membrane.

Figure S2 Absorption of E. coli on the membranes in dead-end cell.

Abbreviations: E. coli, Escherichia coli; MWCNT, multi-walled carbon nanotube; NSSM, nanoporous solid-state membrane.

Figure S3 Plate count method in absorption studies.

Note: Counting the colonies of concentration (A) 1.5 × 10⁸ and (B) 10⁷.

Table S1 Parameters of acid-base Van Oss method

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Acknowledgments

Our research group appreciates all those who collaborated with us on this project.

Disclosure

The authors report no conflicts of interest in this work.