Immobilization of tyrosinase on polyacrylonitrile beads: biodegradation of phenol from aqueous solution and the relevant cytotoxicity assessment

Abstract

An economical and stabilized immobilized-enzyme method was developed for the removal of phenol in wastewater. Tyrosinase was immobilized on the PAN-based beads with glutaraldehyde as was confirmed successfully by a series of characterizations involving Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The biodegradation of phenol was investigated by using the immobilized beads and compared to free tyrosinase. The optimum pH and temperature were determined to be 7.0 and 40 C, respectively.Experiments showed that the immobilized tyrosinase was much more stable than the free tyrosinase in storage and that the immobilized tyrosinase could even retain about 78% of its original activity after repeated use 6 times in a batch system. Furthermore, the comparative in vitro cytotoxicity of phenol/ treated solutions were evaluated in LO2 and HepG2 cells by using the CCK-8 assay for cell viability along with flow cytometry detection for apoptosis. The results showed that the toxicity of the phenol solutions only exerted toxicity on cells in a certain concentration range (>0.5 mM for LO2 and HepG2 cells) and that the toxicity of the phenol solutions was greatly decreased after treatment with the tyrosinaseimmobilized beads. Thereby, the results confirm that we have established a suitable strategy with promising application to remove phenol economically and efficiently, which could even lower the toxicity of phenol at the cellular level.

Tyrosinase from <i>Penicillium chrysogenum</i>: Characterization and application in phenol removal from aqueous solution

“…The immobilized enzyme retained about 70% of its original activity after 8 repeated cycles, suggesting a good candidate for industrial applications. A similar result was demonstrated for the immobilized tyrosinase on polyacrylonitrile (Wu et al, 2017).…”

“…The obtained results may be attributed to the tyrosinasealdehyde groups reaching saturation at 4h, the equilibrium of aldimine condensation and the change of the active site of the immobilized enzymes (Barbosa et al, 2012). A previous study mentioned that the residual activity of immobilized tyrosinase exhibited a constant value after 12 h and then changed slowly over time (Wu et al, 2017).…”

“…The reaction was performed at 35ºC for 12 h with shaking at 150 g and stopped by adding 100mM phosphoric acid. The degradation of phenol was determined according to Wu et al(2017).…”

“…Tyrosinases are capable of oxidizing phenolic contaminants to nontoxic forms and hence applicable in wastewater treatment (Nawaz et al, 2017). Previous work reported a high efficiency of the immobilized tyrosinase for phenol degradation in aqueous solution over the free enzyme (Wu et al, 2017). The tyrosinase enzyme from Streptomyces espinosus strain LK-4 reported to be an efficient enzyme for the removal of phenolic compounds from industrial wastewater (Roy et al, 2014).…”

Preparation of novel 1,2,3-triazole furocoumarin derivatives via click chemistry and their anti-vitiligo activity

“…8 Among them, TYR is the rate-limiting enzyme and is mainly involved in two distinct reactions of melanin synthesis: rstly, the hydroxylation of a monophenol and secondly, the conversion of an o-diphenol to the corresponding o-quinone. 9,10 Presently, there are several drugs used for the treatment of vitiligo including photosensitizer (8-MOP, khellin), topical corticosteroids (dexamethasone), calcineurin inhibitors (tacrolimus), vitamin D3 analogs (tacalcitol), 11 and JAK inhibitors (ruxolitinib, baricitinib, tofacitinib) ( Fig. 2), which are oen used for myelodysplastic disorders, were recently proven to be efficacious for vitiligo based on a large number of clinical cases.…”