Characterization of immobilized tyrosinase – an enzyme that is stable in organic solvent at 100 °C

Wu, Lidong; Rathi, Brijesh; Chen, Yi; Wu, Xiuhong; Liu, Huan; Li, Jincheng; Ming, Anjie; Han, Gang

doi:10.1039/c8ra07559j

Cited by 8 publications

(4 citation statements)

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“…Examples of successful uses of TCO in optoelectronics are abundant, from well‐established state‐of‐the‐art devices such as silicon heterojunction solar cells and inorganic and organic light‐emitting diodes (LEDs) to perovskite solar cells (PSCs), and organic solar cells. [ 5–8 ] There are also many examples of TCOs in new approaches that simultaneously require semitransparency and flexibility, such as semitransparent conductors, field‐effect transistors, thermal shields, photo‐detectors, and vertical transistors. [ 9–14 ] PSCs have attracted much interest since their onset in 2009 due to rapidly‐increasing power conversion efficiencies (currently above 25% for small area cells).…”

Section: Introductionmentioning

confidence: 99%

ITO Top‐Electrodes via Industrial‐Scale PLD for Efficient Buffer‐Layer‐Free Semitransparent Perovskite Solar Cells

Zanoni

Paliwal

Hernández-Fenollosa

et al. 2022

Adv Materials Technologies

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well-established state-of-the-art devices such as silicon heterojunction solar cells and inorganic and organic light-emitting diodes (LEDs) to perovskite solar cells (PSCs), and organic solar cells. [5][6][7][8] There are also many examples of TCOs in new approaches that simultaneously require semitransparency and flexibility, such as semitransparent conductors, field-effect transistors, thermal shields, photo-detectors, and vertical transistors. [9][10][11][12][13][14] PSCs have attracted much interest since their onset in 2009 due to rapidly-increasing power conversion efficiencies (currently above 25% for small area cells). The perovskite layer and any adjacent charge transport layers can be fabricated in many ways using either solution-based processes or vacuum-assisted deposition. Vacuum-based deposition has the advantage of better control over the film thickness and is an additive method, moreover, it is a widely employed method of production of the before mentioned opto-electronic devices. [15,16] Despite the benefits and promising perspectives of using TCOs in optoelectronics, the development of organic/TCO (TCO on top of organic) bi-layer structures is still a non-trivial challenge because of the generally harsh processing conditions involved in the deposition of the TCO layers. [17] For both lab-and industrial-scale deposition of TCO, magnetron sputtering is the most widespread technique. It is a vacuumbased process that employs direct current or radio frequency to excite a carrier gas (most commonly Ar) into a high kinetic energy plasma which bombards a target material, resulting in the transfer of fragments from the target to substrates positioned above it. However, the accelerated particles, together with side phenomena such as plasma luminescence and processing-induced heat, can easily damage soft organic semiconductor layers, leading to increased leakage current, as well as reduced efficiency and a lower lifetime of the optoelectronic device. [18,19] To overcome this limitation, a protective buffer layer is deposited prior to the TCO deposition. [17] Also, many efforts were proposed to minimize damages of sputtering deposition on buffer-layer-free stacks by lowering the power density threshold by changes in power, target to substrate distance, sputtering gas, and process pressure, [20][21][22][23][24] but at the expense of longer processing times. [22,[25][26][27][28][29] Among these reports, the most efficient buffer-layer-free PSC using TCO top-electrode was achieved by Ramos et al. employing a post-annealed ITO sputtered directly onto a thick (290 nm) spiro-OMeTAD hole The deposition of transparent conductive oxides (TCO) usually employs harsh conditions that are frequently harmful to soft/organic underlayers. Herein, successful use of an industrial pulsed laser deposition (PLD) tool to directly deposit indium tin oxide (ITO) films on semitransparent vacuum-deposited perovskite solar cells without damage to the device stack is demonstrated. The morphological, electronic, and optical properties o...

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Section: Introductionmentioning

confidence: 99%

ITO Top‐Electrodes via Industrial‐Scale PLD for Efficient Buffer‐Layer‐Free Semitransparent Perovskite Solar Cells

Zanoni

Paliwal

Hernández-Fenollosa

et al. 2022

Adv Materials Technologies

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“…However, once a certain level is reached, the concentration of melanin begins to decline. This decline may be attributed to the inhibition of enzyme activity at high tyrosine concentrations, causing a decrease in melanin production (Wu et al 2018). The results suggest that the magnetic immobilized tyrosinase enzyme can effectively convert tyrosine to melanin, with the highest concentration obtained at a tyrosine concentration of 0.1.…”

Section: )mentioning

confidence: 99%

Tyrosinase Enzyme Purification and Immobilization from Pseudomonas sp. EG22 Using Cellulose Coated Magnetic Nanoparticles: Characterization of Bioactivity in Melanin Product

El-Aziz

Faraag

Ibrahim

et al. 2023

Preprint

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Melanin is a brown-black pigment produced by a variety of organisms and has significant roles in various biological processes such as insect cuticle sclerotization, wound healing, and fruit ripening. The tyrosinase enzyme catalyzes the conversion of tyrosine to melanin. Research on this enzyme and its derivatives has revealed promising uses in the pharmaceutical and biotechnology sectors. The aim of this research is to purify and immobilize the tyrosinase enzyme from Pseudomonas sp. EG22 using cellulose-coated magnetic nanoparticles. Various techniques, such as UV-visible spectroscopy, transmission electron microscopy (TEM), Zeta Sizer Nano ZS, and FTIR, were utilized to examine the synthesized nanoparticles. According to the findings, the nanoparticles exhibited a spherical shape with an average diameter of 12 nm. Furthermore, they possessed a negative surface charge, as evidenced by a polydispersity index (PDI) of 0.260 and a surface potential of -55.7 mV. The antibacterial and anticancer bioactivity of the enzyme's melanin product is also investigated. Results of the study indicated optimum tyrosinase activity at pH 6 and 35°C and increased with increasing tyrosine concentration. The results indicate that by immobilizing the tyrosinase enzyme on cellulose coated magnetic nanoparticles, its stability can be improved, enabling longer usage. Moreover, this method could prove beneficial in increasing the production of melanin. Produced melanin showed potential antibacterial activity against multi-drug resistant strain of Citrobacter freundii. The potential of melanin pigment to decrease cell survival and induce apoptosis in initiation cells was demonstrated. When treated with the IC50 concentration, HepG2 cells showed reduced resistance to melanin pigment.

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“…Tyrosinase has been immobilized on various carriers and its biocatalytic properties have been studied and compared to those of the free enzyme [ 25 , 26 , 27 , 28 , 29 ]; these studies showed that the immobilized form exhibits enhanced activity and stability. Cross-linking of enzyme molecules is another immobilization technique used for tyrosinase.…”

Section: Introductionmentioning

confidence: 99%

Tyrosinase Magnetic Cross-Linked Enzyme Aggregates: Biocatalytic Study in Deep Eutectic Solvent Aqueous Solutions

et al. 2023

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In the field of biocatalysis, the implementation of sustainable processes such as enzyme immobilization or employment of environmentally friendly solvents, like Deep Eutectic Solvents (DESs) are of paramount importance. In this work, tyrosinase was extracted from fresh mushrooms and used in a carrier-free immobilization towards the preparation of both non-magnetic and magnetic cross-linked enzyme aggregates (CLEAs). The prepared biocatalyst was characterized and the biocatalytic and structural traits of free tyrosinase and tyrosinase magnetic CLEAs (mCLEAs) were evaluated in numerous DES aqueous solutions. The results showed that the nature and the concentration of the DESs used as co-solvents significantly affected the catalytic activity and stability of tyrosinase, while the immobilization enhanced the activity of the enzyme in comparison with the non-immobilized enzyme up to 3.6-fold. The biocatalyst retained the 100% of its initial activity after storage at −20 °C for 1 year and the 90% of its activity after 5 repeated cycles. Tyrosinase mCLEAs were further applied in the homogeneous modification of chitosan with caffeic acid in the presence of DES. The biocatalyst demonstrated great ability in the functionalization of chitosan with caffeic acid in the presence of 10% v/v DES [Bet:Gly (1:3)], enhancing the antioxidant activity of the films.

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Characterization of immobilized tyrosinase – an enzyme that is stable in organic solvent at 100 °C

Abstract: Immobilized tyrosinase in hexane can withstand 100 °C over one week, and the half-life of the dry immobilized tyrosinase in organic solvent is strongly related to the polarity of the organic solvent.

Cited by 8 publications

References 50 publications

ITO Top‐Electrodes via Industrial‐Scale PLD for Efficient Buffer‐Layer‐Free Semitransparent Perovskite Solar Cells

ITO Top‐Electrodes via Industrial‐Scale PLD for Efficient Buffer‐Layer‐Free Semitransparent Perovskite Solar Cells

Tyrosinase Enzyme Purification and Immobilization from Pseudomonas sp. EG22 Using Cellulose Coated Magnetic Nanoparticles: Characterization of Bioactivity in Melanin Product

Tyrosinase Magnetic Cross-Linked Enzyme Aggregates: Biocatalytic Study in Deep Eutectic Solvent Aqueous Solutions

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