Aspergillus niger PA2 Tyrosinase Covalently Immobilized on a Novel Eco-Friendly Bio-Composite of Chitosan-Gelatin and Its Evaluation for L-DOPA Production

In vitro and in vivo assessment of curcumin-quercetin loaded multi-layered 3D-nanofibroporous matrix prepared by solution blow-spinning for full-thickness burn wound healing

Burn wounds (BWs) cause impairment of native skin tissue and may cause significant microbial infections that demand immediate care. Curcumin (Cur) and quercetin (Que) exhibit antimicrobial, hemocompatibility, ROS-scavenging, and anti-inflammatory properties. However, its instability, water insolubility, and low biological fluid absorption render it challenging to sustain local Cur and Que doses at the wound site. Therefore, to combat these limitations, we employed blow-spinning and freeze-drying to develop a multi-layered, Cur/Que-loaded gelatin/chitosan/PCL (GCP-Q/C) nanofibroporous (NFP) matrix. Morphological analysis of the NFP-matrix using SEM revealed a well-formed multi-layered structure. The FTIR and XRD plots demonstrated dual-bioactive incorporation and scaffold polymer interaction. Additionally, the GCP-Q/C matrix displayed high porosity (82.7 ± 2.07 %), adequate pore size (∼121 μm), enhanced water-uptake ability (∼675 % within 24 h), and satisfactory biodegradation. The scaffolds with bioactives had a long-term release, increased antioxidant activity, and were more effective against gram-positive (S. aureus) and gram-negative (E. coli) bacteria than the unloaded scaffolds. The in vitro findings of GCP-Q/C scaffolds showed promoted L929 cell growth and hemocompatibility. Additionally, an in vivo full-thickness BW investigation found that an implanted GCP-Q/C matrix stimulates rapid recuperation and tissue regeneration. In accordance with the findings, the Gel/Ch/PCL-Que/Cur NFP-matrix could represent an effective wound-healing dressing for BWs.

Immobilization of Aspergillus oryzae tyrosine hydroxylase on ZnO nanocrystals for improved stability and catalytic efficiency towards L-dopa production

The current study focuses on the submerged fermentation of tyrosine hydroxylase (TH) from Aspergillus oryzae IIB-9 and its immobilization on zinc oxide nanocrystals (ZnO-NPs) for increased L-dopa production. The volume of Vogel's medium (75 ml), period of incubation (72 h), initial pH (5.5), and size of inoculum (1.5 ml) were optimal for maximum TH activity. The watch glass-dried (WG) and filter paper-dried (FP) ZnO-NPs were prepared and characterized using analytical techniques. The UV-Vis spectra revealed 295 and 285 nm absorption peaks for WG-ZnO-NPs and FP-ZnO-NPs dispersed in isopropanol. X-ray diffraction analysis confirmed the crystalline nature of ZnO-NPs. FTIR spectra band from 740 to 648.1/cm and 735.8/cm to 650.1/cm showed the stretching vibrations of WG-ZnO-NPs and FP-ZnO-NPs, respectively. The particle size of ZnO-NPs observed by scanning electron microscopy (SEM) images was between 130 and 170 nm. Furthermore, the stability of immobilized TH on ZnO-NPs was determined by varying the incubation period (10 min for WG-NPs and 15 min for FP-NPs) and temperature (45 °C and 30 °C for WG and FP-NPs, respectively). Incubating enzymes with various copper, iron, manganese, and zinc salts studied the catalytic efficiency of TH. Immobilization of TH on ZnO-NPs resulted in an 11.05-fold increase in TH activity, thus enhancing stability and catalytic efficiency.

Spherical porous iron-nitrogen-carbon nanozymes derived from a tannin coordination framework for the preparation of L-DOPA by emulating tyrosine hydroxylase

L-3,4-Dihydroxyphenylalanine (L-DOPA) is widely used in Parkinson's disease treatment and is therefore in high demand. Development of an efficient method for the production of L-DOPA is urgently required. Nanozymes emulating tyrosine hydroxylase have attracted enormous attention for biomimetic synthesis of L-DOPA, but suffered from heterogeneity. Herein, a spherical porous iron-nitrogen-carbon nanozyme was developed for production of L-DOPA. Tannic acid chelated with ferrous ions to form a tannin-iron coordination framework as a carbon precursor. Iron and nitrogen co-doped carbon nanospheres were assembled via an evaporation-induced self-assembly process using urea as a nitrogen source, F127 as a soft template, and formaldehyde as a crosslinker. The nanozyme was obtained after carbonization and acid etching. The nanozyme possessed a dispersive iron atom anchored in the Fe-N coordination structure as an active site to mimic the active center of tyrosine hydroxylase. The material showed spherical morphology, uniform size, high specific surface area, a mesoporous structure and easy magnetic separation. The structural properties could promote the density and accessibility of active sites and facilitate mass transport and electron transfer. The nanozyme exhibited high activity to catalyze the hydroxylation of tyrosine to L-DOPA as tyrosine hydroxylase in the presence of ascorbic acid and hydrogen peroxide. The titer of DOPA reached 1.2 mM. The nanozyme showed good reusability and comparable enzyme kinetics to tyrosine hydroxylase with a Michaelis-Menten constant of 2.3 mM. The major active species was the hydroxyl radical. Biomimetic simulation of tyrosine hydroxylase using a nanozyme with a fine structure provided a new route for the efficient production of L-DOPA.

A review on nonviral, nonbacterial infectious agents toxicity involved in neurodegenerative diseases

Neuronal death, decreased activity or dysfunction of neurotransmitters are some of the pathophysiological reasons for neurodegenerative diseases like Alzheimer's, Parkinson's and multiple sclerosis. Also, there is evidence for the role of infections and infectious agents in neurodegenerative diseases and the effect of some metabolites in microorganisms in the pathophysiology of these diseases. In this study, we intend to evaluate the existing studies on the role of infectious agents and their metabolites on the pathophysiology of neurodegenerative diseases. PubMed, Scopus, Google Scholar and Web of Science search engines were searched. Some infectious agents have been observed in neurodegenerative diseases. Also, isolations of some fungi and microalgae have an improving effect on Parkinson's and Alzheimer's.

Development of engineered probiotics with tailored functional properties and their application in food science

The potential health benefits of probiotics may not be cognized because of the substantial curtailment in their viability during food storage and passage through the gastrointestinal system. Intestinal flora composition, and resistance against pathogens are among the health benefits associated with probiotic consumption. In the gastric environment, pH 2.0, probiotics dramatically lose their viability during the transit through the gastrointestinal system. The challenge remains to maintain cell viability until it reaches the large intestine. In extreme conditions, such as a decrease in pH or an increase in temperature, encapsulation technology can enhance the viability of probiotics. Probiotic bacterial strains can be encapsulated in a variety of ways. The methods are broadly systematized into two categories, liquid and solid delivery systems. This review emphasizes the technology used in the research and commercial sectors to encapsulate probiotic cells while keeping them alive and the food matrix used to deliver these cells to consumers.

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Bio-imprinted magnetic cross-linked polyphenol oxidase aggregates for enhanced synthesis of L-dopa, a neurodegenerative therapeutic drug

Bio-imprinted magnetic cross-linked enzyme aggregates (i-m-CLEAs) of polyphenol oxidase (PPO) obtained from potato peels were prepared using amino-functionalized magnetic nanoparticles. Bio-imprinting is being used to improve the catalytic efficiency and conformational stability of enzymes. For bio-imprinting, PPO was incubated with different imprint/template molecules (catechol, 4-methyl catechol and l-3,4-dihydroxy phenylalanine) before cross-linking with glutaraldehyde. CLEAs imprinted with 4-methyl catechol showed maximum activity as compared with non-bio-imprinted magnetic CLEAs (m-CLEAs). They were further characterized by scanning electron microscopy and confocal microscopy. In bio-imprinted m-CLEAs, half-life (t_1/2) of PPO significantly improved (364.74 min) as compared to free PPO (43.58 min) and non-bio-imprinted m-CLEAs (266.54 min). Bio-imprinted m-CLEAs showed excellent thermal and storage stability as well as reusability. The CLEAs preparation were used for the synthesis of l-3,4-dihydroxyphenylalanine (L-dopa, a therapeutic drug to treat neurodegenerative disorder) and a remarkable increase in L-dopa yield (23.5-fold) was obtained as compared to free enzyme. A cost effective and reusable method has been described for the production of L-dopa.

Effect of heat-treated Nuruk on the quality characteristics of aged Yakju

Long-term aging of Yakju, a traditional Korean liquor made of rice and Nuruk (a fermentation agent), causes browning and odor and flavor development. This study investigated the effects of heat-treated Nuruk (50-80 °C, 30 min) on Yakju quality. The saccharogenic powers and glucoamylase, α-amylase, and carboxypeptidase activities were similar in non-heat-treated Nuruk and that treated at 50 °C. However, acidic protease and alcohol dehydrogenase decreased above 50 °C. The content of nitrogen-containing compounds was inversely proportional to the heat-treatment temperature. Compounds that cause off-flavors decreased at 50-60 °C, but increased at 70-80 °C, whereas compounds that provide fragrance increased at 50-60 °C. Sensory evaluation indicated that bad taste attributes were higher in Yakju produced using non-heat-treated Nuruk. Therefore, heat treatment of Nuruk at 50 °C can be adopted as a method for improving Yakju quality, as enzymatic activities that affect color, aroma, and taste are regulated.