Surface engineering of TiO2-MWCNT nanocomposites towards tuning of functionalities and minimizing toxicity
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Multiwall carbon nanotubes were coupled with titanium dioxide (in different mole ratios of titanium and carbon) at the nano-scale, using a simple sonochemical and calcination process. The titanium dioxide-multiwall carbon nanotubes nanocomposites were for the first time surface modified with an innovative biotechnology-based reaction by using laccase to activate and covalently graft gallic acid dimers/oligomers/polymers on the nanocomposite surface in order to impart new functionalities and to minimize the nanocomposites’ toxicity. Structure of the titanium dioxide-multiwall carbon nanotubes, before and after surface modification, was investigated with X-ray powder diffraction, infrared, and UV-visible diffuse reflectance spectroscopy analysis, and scanning electron microscopy. The results indicated preferential formation of anatase titanium dioxide on one hand and covalent grafting of gallic acid dimers/oligomers/polymers functionalities on the nanocomposite surface, on the other. After modification, the antioxidant activity was analyzed using 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and photocatalytic activity toward the liquid-phase degradation of methylene blue in aqueous solution under both UV and visible light irradiation. Up to 98% antioxidant activity of the surface modified nanocomposites was established after 24 h of incubation, whereas non-modified nanocomposite induced the formation of the ABTS•+ radicals. In addition, 1.3-2.8-fold reduction in photocatalytic activity was achieved, depending on the irradiation. Accordingly, the gallic acid dimers/oligomers/polymers modified titanium dioxide-multiwall carbon nanotubes appear to simultaneously exhibit photocatalytic activity with an ability to scavenge free radicals, and can thus be considered as engineered nanoparticles with low toxicity.
KeywordsTiO2-Carbon Nanotube composites Laccase Gallic acid Surface functionalization Photocatalytic activity Antioxidant activity
This work was financially supported by the Slovenian Research Agency (post-doctorate project, grant no. Z2-5493) and a program group for Textile Chemistry P2-0118.
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Conflict of interest
The authors declare that they have no competing of interests.
- 4.Veronovski N, Lešnik M, Lubej A, Verhovšek D (2014) Surface treated titanium dioxide nanoparticles as inorganic UV filters in sunscreen products. Acta Chim Slov 61:595–600Google Scholar
- 7.Lin Y-C (2012) Applying Ag–TiO2/functional filter for abating odor exhausted from semiconductor and opti-electronic industries. Clean Technol Environ Policy 15:359–366Google Scholar
- 8.Božič M, Vivod V, Vogrinčič R et al. (2015) Enhanced catalytic activity of the surface modified TiO2-MWCNT nanocomposites under visible light. J Colloid Interface Sci 465:93–105Google Scholar
- 9.Dubey A, Goswami M, Yadav K, Chaudhary D (2015) Oxidative stress and nano-toxicity induced by TiO2 and ZnO on WAG cell line. PLoS One 26:1–26Google Scholar
- 10.Anderson WA (2015) Toxicity associated with the photo catalytic and photo stable forms of titanium dioxide nanoparticles used in sunscreen toxicity associated with the photo catalytic and photo stable forms of titanium dioxide nanoparticles used in sunscreen. MedCrave 1:1–18Google Scholar
- 29.Chen M-L, Oh W-C (2011) Synthesis and highly visible-induced photocatalytic activity of CNT-CdSe composite for methylene blue solution. Nanoscale Res Lett 6:1–8Google Scholar
- 32.Cordeiro D, Vasconcelos L, Costa VC et al. (2011) Infrared spectroscopy of titania sol-gel coatings on 316L stainless steel. Mater Sci Appl 2011:1375–1382Google Scholar