title: Highly Efficient and Stable Novel NanoBiohybrid Catalyst to Avert 3,4-Dihydroxybenzoic Acid Pollutant in Water.
abstract: The present study reported for the first time covalent immobilization of protocatechuate 3,4-dioxygenase (3,4-POD) onto functionalized multi-walled carbon nanotubes (F-MWCNT) for degrading the toxic 3,4-dihydroxybenzoic acid (3,4-DHBA) pollutant in water. The F-MWCNTs had a maximum 3,4-POD loading of 1060 μg/mg. Immobilized 3,4 POD had 44% of relative structural changes to its free configurations. Nevertheless, >90% of relative activity and about 50% of catalytic efficiency were retained to the free enzyme. Immobilized 3,4-POD demonstrated higher alkaline stability and thermostability than the free 3,4-POD. The free and immobilized 3,4-POD lost 82% and 66% of relative activities, respectively after 180 min of incubations at 90 °C. Excellent shelf-life was observed for the immobilized 3,4-POD with residual activity of 56% compared with 41% and 39% of the free 3,4-POD at 4 °C and 25 °C over 30 days storage. Immobilized 3,4-POD showed >60% of catalytic activity retention even after ten-cycle uses, defraying the expenses of free 3,4-POD productions for long term uses. Finally, the immobilized 3,4-POD removed 71% of 3,4-DHBA from water in <4 h, paving its future application for water purification with reduced costs and time.
authors.affiliation: Nanotechnology and Catalysis Research Center (NANOCAT), University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Rasel
authors.initials: R
authors.lastname: Das
authors.affiliation: Nanotechnology and Catalysis Research Center (NANOCAT), University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Sharifah Bee Abd
authors.initials: SB
authors.lastname: Hamid
authors.affiliation: Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Mohamad Suffian Mohamad
authors.initials: MS
authors.lastname: Annuar