Development of novel flexible sugar ester vesicles as carrier systems for the antioxidant enzyme catalase for wound healing applications

Catalase immobilization: Current knowledge, key insights, applications, and future prospects - A review

Catalase (CAT), a ubiquitous enzyme in all oxygen-exposed organisms, effectively decomposes hydrogen peroxide (H2O2), a harmful by-product, into water and oxygen, mitigating oxidative stress and cellular damage, safeguarding cellular organelles and tissues. Therefore, CAT plays a crucial role in maintaining cellular homeostasis and function. Owing to its pivotal role, CAT has garnered considerable interest. However, many challenges arise when used, especially in multiple practical processes. "Immobilization", a widely-used technique, can help improve enzyme properties. CAT immobilization offers numerous advantages, including enhanced stability, reusability, and facilitated downstream processing. This review presents a comprehensive overview of CAT immobilization. It starts with discussing various immobilization mechanisms, support materials, advantages, drawbacks, and factors influencing the performance of immobilized CAT. Moreover, the review explores the application of the immobilized CAT in various industries and its prospects, highlighting its essential role in diverse fields and stimulating further research and investigation. Furthermore, the review highlights some of the world's leading companies in the field of the CAT industry and their substantial potential for economic contribution. This review aims to serve as a discerning, source of information for researchers seeking a comprehensive cutting-edge overview of this rapidly evolving field and have been overwhelmed by the size of publications.

Stabilization of Eversa® Transform 2.0 lipase with sorbitol to enhance the efficiency of ultrasound-assisted biodiesel production

Ultrasound technology has emerged as a promising tool for enhancing enzymatic biodiesel production, yet the cavitation effect induced can compromise enzyme stability. This study explored the efficiency of polyols in enhancing lipase stability under ultrasound conditions to further improve biodiesel yield. The incorporation of sorbitol resulted in the highest fatty acid methyl ester (FAME) content in the ultrasound-assisted biodiesel production catalyzed by Eversa® Transform 2.0 among the investigated polyols. Furthermore, sorbitol enhanced the stability of the lipase, allowing it to tolerate up to 100 % ultrasound amplitude, compared to 60 % amplitude in its absence. Enzyme activity assays revealed that sorbitol preserved 99 % of the lipase activity, in contrast to 84 % retention observed without sorbitol under an 80 % ultrasound amplitude. Circular dichroism (CD) and fluorescence spectroscopy analyses confirmed that sorbitol enhanced lipase rigidity and preserved its conformational structure under ultrasound exposure. Furthermore, employing a stepwise methanol addition strategy in ultrasound-assisted reactions with sorbitol achieved an 81.2 wt% FAME content in 8 h with only 0.2 wt% enzyme concentration. This promising result highlights the potential of sorbitol as a stabilizing agent in ultrasound-assisted enzymatic biodiesel production, offering a viable approach for enhancing biodiesel yield and enzyme stability in industrial applications.

Proteome Alterations and Nucleosome Activation in Rat Myoblasts Treated with Cerium Oxide Nanoparticles

Oxidative stress is a widespread causative agent of disease. Together with its general relevance for biomedicine, such a dynamic is recognizably detrimental to space exploration. Among other solutions, cerium oxide nanoparticles (or nanoceria, NC) display a long-lasting, self-renewable antioxidant activity. In a previous experiment, we evaluated oxidative imbalance in rat myoblasts in space, aboard the International Space Station, and unveiled possible protective effects from NC through RNA sequencing. Here, we focus on the myoblast response to NC on land by means of proteomics, defining a list of proteins that putatively react to NC and confirming nucleosomes/histones as likely mediators of its molecular action. The proteomics data set we present here and its counterpart from the space study share four factors. These are coherently either up- (Hist1h4b) or down-regulated (Gnl3, Mtdh, Trip12) upon NC exposure.

Effective Soybean Oil Degumming by Immobilized Phospholipases A2 from Walterinnesia aegyptia Venom

Enzymatic degumming utilizing phospholipase enzymes could be used in ecologically friendly procedures with enhanced oil recovery yields. In this study, two phospholipases A2 of group I and II, WaPLA2-I and WaPLA2-II, from the snake venom of Saudi Walterinnesia aegyptia were evaluated for soybean oil degumming after being immobilized on three different support materials (calcium alginate (CA), CA-gelatin (CAG), and CA-chitosan (CAC), and cross-linked with glutaraldehyde). Higher yields of CAC-immobilized PLA2-I (85 ± 3%) and PLA2-II (87 ± 3.6%) compared to CAG (77.3 ± 2.1 and 79 ± 2.6%, respectively) and CA beads (55.7 ± 2.5% and 57.3 ± 3.1%, respectively) were observed. In addition, the optimal temperature of immobilized WaPLA2-I and WaPLA2-II increased from 45 to 55 °C and from 55 to 65 °C, respectively. Their stability at high temperatures was also significantly enhanced covering a larger range (70-80 °C). Likewise, the pH/activity profile of WaPLA2 was greatly expanded upon immobilization with the pH-optima being shifted by 0.5 to 1 pH unit to the basic side. Similarly, the stability of WaPLA2s in the presence of organic solvents was also significantly improved, while the affinity for calcium and bile salt was the same for both free and immobilized enzymes. Interestingly, the remaining activity of immobilized WaPLA2 onto different supports was more than 50 or 60% after eight recycles or 120 days of storage at 4 °C, respectively. CAC-WaPLA2-II was the best immobilized enzyme complex for the oil degumming process by reducing its final residual phosphorus content from 168 mg/kg to less than 10 mg/kg in only 4 h. Overall, CAC-WaPLA2-II showed the most attractive profiles of temperature, pH, and reaction duration as well as significant storage stability and reusability.

Development of chia gum/alginate-polymer support for horseradish peroxidase immobilization and its application in phenolic removal

Chia gum's molecular structure with distinctive properties as well as the alginate-based hydrogel's three-dimensionally cross-linked structure can provide a potent matrix for immobilization of enzyme. Herein, chia gum (CG)/alginate (A)-polymeric complex was synthesized and employed as a support material for the immobilization of horseradish peroxidase (HRP). HRP was successfully immobilized on the developed ACG-polymeric support, and the highest immobilization recovery (75%) was observed at 1.0% CG and 2% A, pH 7.0, and 50 units of the enzyme. The structure, morphology, and thermal properties of the prepared ACG-HRP were demonstrated using Fourier Transform Infrared (FTIR), Scanning Electron Microscope, and Thermogravimetric (TGA) analyses. ACG-HRP showed a good reusability (60%) over ten reuses. The immobilized ACG-HRP displayed an acidic pH optimum (6.0), a higher temperature optimum (50 °C), and improved thermal stability (30-50 °C) compared to the soluble HRP at pH 7.0, 40 °C and (30-40 °C), respectively. ACG-HRP has a lower affinity for hydrogen peroxide (H2O2) and guaiacol and a higher oxidizing affinity for a number of phenolic substrates. The ACG-HRP demonstrated greater resistance to heavy metals, isopropanol, urea, Triton X-100, and urea, as well as improved efficiency for eliminating phenol and p-chlorophenol. The developed ACG-polymeric support provided improved enzyme properties, allowed the reuse of the immobilized HRP in 10 cycles, and made it promising for several biotechnological applications.

Enzymes for dermatological use

Skin is the ultimate barrier between body and environment and prevents water loss and penetration of pathogens and toxins. Internal and external stressors, such as ultraviolet radiation (UVR), can damage skin integrity and lead to disorders. Therefore, skin health and skin ageing are important concerns and increased research from cosmetic and pharmaceutical sectors aims to improve skin conditions and provide new anti-ageing treatments. Biomolecules, compared to low molecular weight drugs and cosmetic ingredients, can offer high levels of specificity. Topically applied enzymes have been investigated to treat the adverse effects of sunlight, pollution and other external agents. Enzymes, with a diverse range of targets, present potential for dermatological use such as antioxidant enzymes, proteases and repairing enzymes. In this review, we discuss enzymes for dermatological applications and the challenges associated in this growing field.

A Comprehensive Review on Niosomes as a Tool for Advanced Drug Delivery

Over the past few decades, advancements in nanocarrier-based therapeutic delivery have been significant, and niosomes research has recently received much interest. The self-assembled nonionic surfactant vesicles lead to the production of niosomes. The most recent nanocarriers, niosomes, are self-assembled vesicles made of nonionic surfactants with or without the proper quantities of cholesterol or other amphiphilic molecules. Because of their durability, low cost of components, largescale production, simple maintenance, and high entrapment efficiency, niosomes are being used more frequently. Additionally, they enhance pharmacokinetics, reduce toxicity, enhance the solubility of poorly water-soluble compounds, & increase bioavailability. One of the most crucial features of niosomes is their controlled release and targeted diffusion, which is utilized for treating cancer, infectious diseases, and other problems. In this review article, we have covered all the fundamental information about niosomes, including preparation techniques, niosomes types, factors influencing their formation, niosomes evaluation, applications, and administration routes, along with recent developments.

Optimization of catalytic properties of Mucor racemosus lipase through immobilization in a biocompatible alginate gelatin hydrogel matrix for free fatty acid production: a sustainable robust biocatalyst for ultrasound-assisted olive oil hydrolysis

Immobilization is a key technology that improves the operational stability of enzymes. In this study, alginate-gelatin (Alg-Gel) hydrogel matrix was synthesized and used as immobilization support for Mucor racemosus lipase (Lip). Enzyme catalyzed ultrasound-assisted hydrolysis of olive oil was also investigated. Alg-Gel matrix exhibited high entrapment efficiency (94.5%) with a degradation rate of 42% after 30 days. The hydrolysis of olive oil using Alg-Gel-Lip increased significantly (P < 0.05) as compared to free Lip. Optimum pH and temperature were determined as pH 5.0 and 40 °C, respectively. The Vmax values for free and immobilized Lip were determined to be 5.5 mM and 5.8 mM oleic acid/min/ml, respectively, and the Km values were 2.2 and 2.58 mM/ml respectively. Thermal stability was highly improved for Alg-Gel-Lip (t1/2 650 min and Ed 87.96 kJ/mol) over free Lip (t1/2 150 min and Ed 23.36 kJ/mol). The enzymatic activity of Alg-Gel-Lip was preserved at 96% after four consecutive cycles and 90% of the initial activity after storage for 60 days at 4 °C. Alg-Gel-Lip catalyzed olive oil hydrolysis using ultrasound showed a significant (P < 0.05) increase in hydrolysis rate compared to free Lip (from 0.0 to 58.2%, within the first 2 h). In contrast to traditional methodology, using ultrasonic improved temperature-dependent enzymatic catalyzed reactions and delivered greater reaction yields. Results suggest that Alg-Gel-Lip biocatalyst has great industrial application potential, particularly for free fatty acid production. In addition, the combined use of enzyme and ultrasound has the potential of eco-friendly technology.

Effect of organic additives on storage stability of camel liver catalase against environmental conditions

The storage stability of catalase is very low under practical reaction conditions. Therefore, this study is aimed to evaluate the storage stability of catalase from camel liver by treated it with polyethylene glycol (PEG), glycerol, bovine serum albumin (BSA) and glucose against different storage conditions. The effect of some additives as stabilizers on the storage stability of camel liver catalase at 4°C and 30°C after 30 and 90 days was studied. The enzyme with additives at 5%concentration was more stable at 4 and 30°C for 90 days of incubation than native enzyme. The activity of catalase was more thermal stable in presence of 5%additive. The activity of enzyme with 5%BSA and glucose was retained 60%of its activity at 60°C. At pH 11 the catalase with glucose retained 30%of its activity. The native enzyme lost 80%of its activity in presence of 5 mM β-mercaptoethanol, where the enzyme with additive retained 30–46%of its activity. At 8 M urea, the native enzyme and enzyme with 5%of all additives retained 28%and 61–77%of its activity, respectively. The catalase with additives retained 50–90%of its activity in presence of different dyes. The results appeared that the catalase with additives may be used for elimination of excess of hydrogen peroxide after bleaching of textile.

The Stability Improvement of Aspergillus fumigatus α-Amylase by Immobilization onto Chitin-Bentonite Hybrid

Enzyme immobilization is a powerful method to improve the stability, reuse, and enzymatic properties of enzymes. The immobilization of the α-amylase enzyme from Aspergillus fumigatus on a chitin-bentonite (CB) hybrid has been studied to improve its stability. Therefore, this study aims to obtain the higher stability of α-amylase enzyme to reduce industrial costs. The procedures were performed as follows: production, isolation, partial purification, immobilization, and characterization of the free and immobilized enzymes. The CB hybrid was synthesized by bentonite, chitin, and glutaraldehyde as a cross-linker. The free enzyme was immobilized onto CB hybrid using 0.1 M phosphate buffer pH 7.5. The free and immobilized enzymes were characterized by optimum temperature, Michaelis constant (K_M), maximum velocity (V_max), thermal inactivation rate constant (k_i), half-life (t_1/2), and transformation of free energy because of denaturation (ΔG_i). The free enzyme has optimum temperature of 55°C, K_M = 3.04 mg mL⁻¹ substrate, V_max=10.90 μmolemL⁻¹min⁻¹, k_i = 0.0171 min⁻¹, t_1/2 = 40.53 min, and ΔG_i = 104.47 kJ mole⁻¹. Meanwhile, the immobilized enzyme has optimum temperature of 60°C, K_M = 11.57 mg mL⁻¹ substrate, V_max=3.37 μmolemL⁻¹min⁻¹, k_i = 0.0045 min⁻¹, t_1/2 = 154.00 min, and ΔG_i = 108.17 kJ mole⁻¹. After sixth cycle of reuse, the residual activity of the immobilized enzyme was 38%. The improvement in the stability of α-amylase immobilized on the CB hybrid based on the increase in half-life was four times of the free enzyme.

Antioxidant-biocompatible and stable catalase-based gelatin-alginate hydrogel scaffold with thermal wound healing capability: immobilization and delivery approach

Hydrogel-based matrix prepared using biopolymers is a new frontier of emerging platforms for enzyme immobilization for biomedical applications. Catalase (CAT) delivery can be effective in inhibiting reactive oxygen species (ROS)-mediated prolongation of the wound healing process. In this study, to improve CAT stability for effective application, gelatin(Gel)–alginate (Alg) biocompatible hydrogel (Gel–Alg), as immobilization support, was prepared using calcium chloride as an ionic cross-linker. High entrapment efficiency of 92% was obtained with 2% Gel and 1.5% Alg. Hydrogel immobilized CAT (CAT–Gel–Alg) showed a wide range of pH from 4 to 9 and temperature stability between 20 to 60 °C, compared to free CAT. CAT–Gel–Alg kinetic parameters revealed an increased K_m (24.15 mM) and a decreased V_max (1.39 µmol H₂O₂/mg protein min) × 10⁴. CAT–Gel–Alg retained 52% of its original activity after 20 consecutive catalytic runs and displayed improved thermal stability with a higher t_1/2 value (half-life of 100.43 vs. 46 min). In addition, 85% of the initial activity was maintained after 8 weeks’ storage at 4 °C. At 24 h after thermal injury, a statistically significant difference in lesion sizes between the treated group and the control group was reported. Finally, our findings suggest that the superior CAT–Gel–Alg stability and reusability are resonant features for efficient biomedical applications, and ROS scavenging by CAT in the post-burn phase offers protection for local treatment of burned tissues with encouraging wound healing kinetics.

The Stability Improvement of α-Amylase Enzyme from Aspergillus fumigatus by Immobilization on a Bentonite Matrix

The stability of the α-amylase enzyme has been improved from Aspergillus fumigatus using the immobilization method on a bentonite matrix. Therefore, this study aims to obtain the higher stability of α-amylase enzyme from A. fumigatus; hence, it is used repeatedly to reduce industrial costs. The procedures involved enzyme production, isolation, partial purification, immobilization, and characterization. Furthermore, the soluble enzyme was immobilized using 0.1 M phosphate buffer of pH 7.5 on a bentonite matrix, after which it was characterized with the following parameters such as optimum temperature, Michaelis constant (K _M ), maximum velocity (V _max), thermal inactivation rate constant (k _i), half-life (t _1/2), and the change of energy due to denaturation (ΔG _i ). The results showed that the soluble enzyme has an optimum temperature of 55°C, K _M of 3.04 mg mL^-1 substrate, V _max of 10.90 μmole mL^-1 min^-1, k _i of 0.0171 min^-1, t_1/2 of 40.53 min, and ΔG _i of 104.47 kJ mole^-1, while the immobilized enzyme has an optimum temperature of 70°C, K _M of 8.31 mg mL^-1 substrate, V _max of 1.44 μmole mL^-1 min^-1, k _i of 0.0060 min^-1, t _1/2 of 115.50 min, and ΔG _i of 107.37 kJ mole^-1. Considering the results, the immobilized enzyme retained 42% of its residual activity after six reuse cycles. Additionally, the stability improvement of the α-amylase enzyme by immobilization on a bentonite matrix, based on the increase in half-life, was three times greater than the soluble enzyme.

Catalase Activity in Keratinocytes, Stratum Corneum, and Defatted Algae Biomass as a Potential Skin Care Ingredient

The generation of reactive oxygen species presents a destructive challenge for the skin organ and there is a clear need to advance skin care formulations aiming at alleviating oxidative stress. The aim of this work was to characterize the activity of the antioxidative enzyme catalase in keratinocytes and in the skin barrier (i.e., the stratum corneum). Further, the goal was to compare the activity levels with the corresponding catalase activity found in defatted algae biomass, which may serve as a source of antioxidative enzymes, as well as other beneficial algae-derived molecules, to be employed in skin care products. For this, an oxygen electrode-based method was employed to determine the catalase activity and the apparent kinetic parameters for purified catalase, as well as catalase naturally present in HaCaT keratinocytes, excised stratum corneum samples collected from pig ears with various amounts of melanin, and defatted algae biomass from the diatom Phaeodactylum tricornutum. Taken together, this work illustrates the versatility of the oxygen electrode-based method for characterizing catalase function in samples with a high degree of complexity and enables the assessment of sample treatment protocols and comparisons between different biological systems related to the skin organ or algae-derived materials as a potential source of skin care ingredients for combating oxidative stress.

Confinement of Metalloenzymes in PEGylated Liposomes to Formulate Colloidal Catalysts for Antioxidant Cascade

Antioxidant cascade reactions detoxifying reactive oxygen species are of significance to control oxidative stresses-triggered diseases. In the present work, the antioxidant catalysts were prepared through the confinement of dual metalloenzymes in liposomes. The amino groups of superoxide dismutase (SOD) were conjugated to the carboxyl groups-bearing liposomes encapsulated with the catalase (CAT) to formulate a spatially organized antioxidant reaction network. The activity of SOD and CAT in the liposomal system was evaluated in detail on the basis of the prolonged xanthine oxidase/xanthine reaction producing superoxide anion radicals (O₂̇^-) and hydrogen peroxide (H₂O₂) coupled with redox reactions of cytochrome c. The liposome-confined SOD and CAT molecules were clearly demonstrated to catalyze the sequential disproportionation of O₂̇^- and H₂O₂ at 25 °C in a potassium phosphate buffer solution (pH = 7.8) under moderate transfer resistance with respect to the intermediate product (H₂O₂) within the liposomes. Furthermore, the liposomal catalysts were modified with the poly(ethylene glycol) (PEG)-conjugated lipids with the molecular mass of the PEG moiety of about 5000 through the post-PEGylation approach. The mean hydrodynamic diameter of the PEGylated liposomal catalysts was 140-150 nm. The dual enzyme activity in liposomes and the thermal stability of the encapsulated CAT were practically unaffected by the PEGylation. The above liposome-based antioxidant catalysts are highly biocompatible, PEG-modifiable, and reactive, thereby making the catalysts potentially applicable to therapeutic materials exhibiting functionality similar to cellular peroxisomes.

Immobilization of Camel Liver Catalase on Nanosilver-Coated Cotton Fabric

Nanoparticles have the advantage of a superior surface area to volume ratio, and thus such materials are useful for enzyme immobilization. A silver nanoparticle coated cotton fabric (AgNp-CF) is used to immobilize camel liver catalase in the present work. The effect of loading levels of AgNp inside cotton fabrics on the immobilization of catalase was investigated. The results revealed that a 6 mL loading level of AgNp precursor (silver nitrate, 2 mM) at pH 8 showed the maximum immobilization efficiency (76%). The morphological properties of the cotton fabric (CF), AgNp-CF and AgNp-CF-catalase were characterized by SEM. The reusability of the immobilized enzyme was tested over ten reuses to show a 67% retained function of its initial activity. Compared with the soluble enzyme’s working pH (6.5), a rather broader working pH (6.5–7.0) was observed for the immobilized catalase. Additionally, the optimum working temperature increased from 30 for the soluble enzyme to 40 °C for the immobilized one, indicating thermal stability. The free and immobilized catalase enzyme’s Km values were 22.5 and 25 mM H2O2, respectively, reflecting the enzyme’s effective properties. The inhibitory effect of metal ions on the enzyme activity was higher toward soluble catalase than the immobilized catalase. This work has developed a method for immobilizing catalase to be useful for several applications.

Highly Selective Entrapment of His-Tagged Enzymes on Superparamagnetic Zirconium-Based MOFs with Robust Renewability to Enhance pH and Thermal Stability

Metal-organic frameworks (MOFs), as a kind of poriferous nanoparticle, are promising candidates for enzyme immobilization to enhance their stability and reusability. However, most MOFs could not specifically immobilize enzymes and regenerate easily, which inevitably leads to serious high consumption and environmental pollution. In this study, renewable and magnetic MOFs were first constructed to specially immobilize His-tagged enzymes from the cell lysates without purification. The immobilized β-glucuronidase exhibited wider pH adaptability and temperature stability. The relative activity of immobilized β-glucuronidase was still maintained at ∼80% after eight cycles. Importantly, after simple treatment, the immobilization capacity of regenerated MOFs after simple treatment was restored to more than 90% in the first three times. The specific magnetic MOFs were proven to be an efficient and renewable platform for one-step immobilization and purification of His-tagged enzymes, showing great potential in industrial applications of nanotechnology and biocatalysis.

Nanoparticles in nanomedicine: a comprehensive updated review on current status, challenges and emerging opportunities

The fast progress in nanomedicine and nanoparticles (NP) materials presents unconventional solutions which are expected to revolutionise health care with great potentials including, enhanced efficacy, bioavailability, drug targeting, and safety. This review provides a comprehensive update on widely used organic and inorganic NP with emphasis on the recent development, challenges and future prospective for bio applications where, further investigations into innovative synthesis methodologies, properties and applications of NP would possibly reveal new improved biomedical relevance. NP exhibits exceptional physical and chemical properties due to their high surface area to volume ratio and nanoscale size, which led to breakthroughs in therapeutic, diagnostic and screening techniques repeated line. Finally, an update of FDA-approved NP is explored where innovative design engineering allowed a paradigmatic shift in their market share. This review would serve as a discerning comprehensive source of information for learners who are seeking a cutting-edge review but have been astounded by the size of publications.

In silico design and pharmacological evaluation of conjugates of atenolol with modified saccharide for cardiovascular targeting

Amongst a wide range of biological macromolecules, saccharides exhibit the potential to be specifically recognized by cell-surface receptors and hence can be utilized as ligands in targeted drug delivery. The current study aims to use saccharides viz. Galactose, Pectin and Chitosan to improve targeting of Atenolol by oxalyl chloride mediated grafting. Conjugates were engineered by grafting Atenolol, a cardiovascular agent with the modified saccharide units. The conjugates were characterized by FTIR, DSC and ¹H NMR study. Drug release analysis and cellular uptake study was carried out using H9c2 cell lines which represent that concentration of drug in cells treated with all atenolol-saccharide conjugates is enhanced by almost two-folds in comparison with cells treated with atenolol solution. Thus cell line study confers the evidence of selective cardiac delivery. No significant cytotoxicity was observed in case of all synthesized conjugates in the Brine shrimp lethality bioassay. Possible binding of the developed conjugates with the GLUT-4 receptors was assessed by in silico analysis using homology model developed by Swiss Model server. Hence it was concluded that the application of these conjugates with saccharides in selective cardiovascular drug delivery can be a promising approach to increase bioavailability, minimize drug loss by degradation and prevent harmful side effects by increasing specific cell targeting.

Catalase-Loaded Silica Nanoparticles Formulated via Direct Surface Modification as Potential Oxygen Generators for Hypoxia Relief

Enzymes are biological catalysts that have many potential industrial and biomedical applications. However, the widespread use of enzymes in the industry has been limited by their instability and poor recovery. In biomedical applications, systemic administration of enzymes has faced two main challenges: limited bioactivity mostly due to rapid degradation by proteases and immunogenic activity, since most enzymes are from nonhuman sources. Herein, we propose a robust enzyme-encapsulation strategy to mitigate these limitations. Catalase (CAT) was encapsulated in nanoporous silica nanoparticles (CAT-SiNPs) by first chemically modifying the enzyme surface with a silica precursor, followed by silica growth and finally poly(ethylene glycol) (PEG) conjugation. The formulation was carried out in mild aqueous conditions and yielded nanoparticles (NPs) with a mean diameter of 230 ± 10 nm and a concentration of 1.3 ± 0.8 × 10¹² NPs/mL. CAT-SiNPs demonstrated high enzyme activity, optimal protection from proteolysis by proteinase K and trypsin, and excellent stability over time. In addition, a new electrochemical assay was developed to measure CAT activity in a rapid, simple, and accurate manner without interference from chromophore usually present in biological samples. Concentrations of 2.5 × 10¹⁰ to 80 × 10¹⁰ CAT-SiNPs/mL not only proved to be nontoxic in cell cultures using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay but also conferred cell protection when cells were exposed to 1 mM hydrogen peroxide (H₂O₂). Finally, the ability of CAT-SiNPs to release oxygen (O₂) when exposed to H₂O₂ was demonstrated in vivo using a rat model. Following the direct injection of CAT-SiNPs in the left kidney, partial pressure of oxygen (pO₂) increased by more than 30 mmHg compared to the contralateral control kidney during the systemic infusion of safe levels of H₂O₂. This pilot study highlights the potential of CAT-SiNPs to generate O₂ to relieve hypoxia in tissues and potentially sensitize tumors against radiation therapy.

Sucrose fatty acid esters: synthesis, emulsifying capacities, biological activities and structure-property profiles

The notable physical and chemical properties of sucrose fatty acid esters have prompted their use in the chemical industry, especially as surfactants, since 1939. Recently, their now well-recognized value as nutraceuticals and as additives in cosmetics has significantly increased demand for ready access to them. As such a review of current methods for the preparation of sucrose fatty acid esters by both chemical and enzymatic means is warranted and is presented here together with an account of the historical development of these compounds as surfactants (emulsifiers). The somewhat belated recognition of the antimicrobial, anticancer and insecticidal activities of sucrose esters is also discussed along with a commentary on their structure-property profiles.

Recent advances in non-ionic surfactant vesicles (niosomes): Fabrication, characterization, pharmaceutical and cosmetic applications

Development of nanocarriers for drug delivery has received considerable attention due to their potential in achieving targeted delivery to the diseased site while sparing the surrounding healthy tissue. Safe and efficient drug delivery has always been a challenge in medicine. During the last decade, a large amount of interest has been drawn on the fabrication of surfactant-based vesicles to improve drug delivery. Niosomes are self-assembled vesicular nano-carriers formed by hydration of non-ionic surfactant, cholesterol or other amphiphilic molecules that serve as a versatile drug delivery system with a variety of applications ranging from dermal delivery to brain-targeted delivery. A large number of research articles have been published reporting their fabrication methods and applications in pharmaceutical and cosmetic fields. Niosomes have the same advantages as liposomes, such as the ability to incorporate both hydrophilic and lipophilic compounds. Besides, niosomes can be fabricated with simple methods, require less production cost and are stable over an extended period, thus overcoming the major drawbacks of liposomes. This review provides a comprehensive summary of niosomal research to date, it provides a detailed overview of the formulation components, types of niosomes, effects of components on the formation of niosomes, fabrication and purification methods, physical characterization techniques of niosomes, recent applications in pharmaceutical field such as in oral, ocular, topical, pulmonary, parental and transmucosal drug delivery, and cosmetic applications. Finally, limitations and the future outlook for this delivery system have also been discussed.

X-ray driven reduction of Cpd I of Catalase-3 from N. crassa reveals differential sensitivity of active sites and formation of ferrous state

Catalases are biotechnologically relevant enzymes because of their applications in food technology, bioremediation, and biomedicine. The dismutation of hydrogen peroxide occurs in two steps; in the first one, the enzyme forms an oxidized compound I (Cpd I) and in the second one, the enzyme is reduced to the ferric state. In this research work, we analyzed the reduction of Cpd I by X-ray radiation damage during diffraction experiments in crystals of CAT-3, a Large-Size Subunit Catalase (LSC) from Neurospora crassa. A Multi-Crystal Data collection Strategy was applied in order to obtain the Cpd I structure at a resolution of 2.2 Å; this intermediate was highly sensitive to X-ray and was easily reduced at very low deposited radiation dose, causing breakage of the Fe=O bond. The comparison of the structures showed reduced intermediates and also evidenced the differential sensitivity per monomer. The resting ferric state was reduced to the ferrous state, an intermediate without a previous report in LSC. The chemically obtained Cpd I and the X-ray reduced intermediates were identified by UV-visible microspectrometry coupled to data collection. The differential sensitivity and the formation of a ferrous state are discussed, emphasizing the importance of the correct interpretation in the oxidation state of the iron heme.

A chemiluminescence-based catalase assay using H2O2-sensitive CdTe quantum dots

A method is described for the chemiluminescence based determination of the activity of catalase (CAT) using H₂O₂-sensitive CdTe quantum dots (QDs). It is based on the finding that the chemiluminescence (CL) of the CdTe/H₂O₂ system is reduced due to the consumption of H₂O₂ by the catalytic action of CAT. The Michaelis constant is calculated to be 519 ± 27 mM, showing the potential of the method to accurately measure the K_m compared to the standard method. The method does not require QDs to be conjugated to biological/organic molecules and therefore is considered to be a rapid and convenient method for determination of CAT in real samples. At an incubation time of 2 s, the LOD was calculated to be 4.5 unit/mL, with a linear range from 6 to 400 unit/mL. The assay is sensitive, simple, and suitable for practical applications. Graphical abstract Schematic representation of chemiluminescence-based catalase U(CAT) assay using the CdSe QD/H₂O₂ system. The reduction of H₂O₂ is reflected by the chemiluminescence of the QDs. A mechanism is put forward based on the changes in chemiluminescence intensity of the QDs by the consumption of H₂O₂ due to the catalytic action of CAT.