A Study of the Activity of Recombinant Mn-Superoxide Dismutase in the Presence of Gold and Silver Nanoparticles

An overview of the direct interaction of synthesized silver nanostructures and enzymes

Silver nanoparticles (AgNPs) have drawn a lot of attention from a variety of fields, particularly the biological and biomedical sciences. As a result, it is acknowledged that AgNPs' direct interactions with macromolecules such as DNA, proteins, and enzymes are essential for both therapeutic and nanotoxicological applications. Enzymes as important catalysts may interact with AgNP surfaces in a variety of ways. Therefore, mechanistic investigation into the molecular effects of AgNPs on enzyme conformation and function is necessary for a comprehensive assessment of their interactions. In this overview, we aimed to overview the various strategies for producing AgNPs. We then discussed the enzyme activity inhibition (EAI) mechanism by nanostructured particles, followed by an in-depth survey of the interaction of AgNPs with different enzymes. Furthermore, various parameters influencing the interaction of NPs and enzymes, as well as the antibacterial and anticancer effects of AgNPs in the context of the enzyme inhibitors, were discussed. In summary, useful information regarding the biological safety and possible therapeutic applications of AgNPs-enzyme conjugates may be obtained from this review.

Opportunities for nanomaterials in enzyme therapy

In recent years, enzyme therapy strategies have rapidly evolved to catalyze essential biochemical reactions with therapeutic potential. These approaches hold particular promise in addressing rare genetic disorders, cancer treatment, neurodegenerative conditions, wound healing, inflammation management, and infectious disease control, among others. There are several primary reasons for the utilization of enzymes as therapeutics: their substrate specificity, their biological compatibility, and their ability to generate a high number of product molecules per enzyme unit. These features have encouraged their application in enzyme replacement therapy where the enzyme serves as the therapeutic agent to rectify abnormal metabolic and physiological processes, enzyme prodrug therapy where the enzyme initiates a clinical effect by activating prodrugs, and enzyme dynamic or starving therapy where the enzyme acts upon host substrate molecules. Currently, there are >20 commercialized products based on therapeutic enzymes, but approval rates are considerably lower than other biologicals. This has stimulated nanobiotechnology in the last years to develop nanoparticle-based solutions that integrate therapeutic enzymes. This approach aims to enhance stability, prevent rapid clearance, reduce immunogenicity, and even enable spatio-temporal activation of the therapeutic catalyst. This comprehensive review delves into emerging trends in the application of therapeutic enzymes, with a particular emphasis on the synergistic opportunities presented by incorporating enzymes into nanomaterials. Such integration holds the promise of enhancing existing therapies or even paving the way for innovative nanotherapeutic approaches.

Immobilized nanoparticles-mediated enzyme therapy; promising way into clinical development

Enzyme (Enz)-mediated therapy indicated a remarkable effect in the treatment of many human cancers and diseases with an insight into clinical phases. Because of insufficient immobilization (Imb) approach and ineffective carrier, Enz therapeutic exhibits low biological efficacy and bio-physicochemical stability. Although efforts have been made to remove the limitations mentioned in clinical trials, efficient Imb-destabilization and modification of nanoparticles (NPs) remain challenging. NP internalization through insufficient membrane permeability, precise endosomal escape, and endonuclease protection following release are the primary development approaches. In recent years, innovative manipulation of the material for Enz immobilization (EI) fabrication and NP preparation has enabled nanomaterial platforms to improve Enz therapeutic outcomes and provide low-diverse clinical applications. In this review article, we examine recent advances in EI approaches and emerging views and explore the impact of Enz-mediated NPs on clinical therapeutic outcomes with at least diverse effects.

A Study of the Interface of Gold Nanoparticles Conjugated to Cowpea Fe-Superoxide Dismutase

The iron superoxide dismutase (FeSOD) is a first barrier to defend photosynthetic organisms from superoxide radicals. Although it is broadly present in plants and bacteria, FeSODs are absent in animals. They belong to the same phylogenic family as Mn-containing SODs, which are also highly efficient at detoxifying superoxide radicals. In addition, SODs can react with peroxynitrite, and FeSOD enzyme has already been used to evaluate the anti-nitrative capacity of plant antioxidants. Gold nanoparticles (AuNPs) have been shown to significantly improve the functionality and the efficiency of ligands, providing they are properly assembled. In this work, the characteristics of the recombinant cowpea (Vigna unguiculata) FeSOD (rVuFeSOD) immobilized onto AuNPs were investigated as a function of (1) NP surface chemistry and (2) biofunctionalization methods, either physical adsorption or covalent bonding. The NP surface chemistry was studied by varying the concentration of the ligand molecule 11-mercaptoundecanoic acid (MUA) on the NP surface. The coverage and activity of the protein on AuNPs was determined and correlated to the surface chemistry and the two biofunctionalization methods. rVuFeSOD-AuNPs conjugate stability was monitored through absorption measurements, agarose gel electrophoresis and DLS, enzymatic activity by a colorimetric assay and by in-gel activity assay, and coverage was measured by colorimetric assay. When using physical adsorption, the NP is the most perturbing agent for the activity of the enzyme. In contrast, only the NP coverage was affected by MUA ligand concentration. However, during covalent attachment, both the NP and the concentration of MUA on the surface influenced the enzyme activity, while the coverage of the NP remained constant. The results evidence the importance of the biomolecule and AuNP interaction for the functionality of the hybrid. These strategies can be used to develop electrochemical biosensors for O2•- and for peroxynitrite in biomedical applications.

Antioxidant enzymes immobilized on gold and silver nanoparticles enhance DNA repairing systems of rat skin after exposure to ultraviolet radiation

The aim of the study was to investigate in vivo whether the application of immobilized superoxide dismutase (SOD) and catalase (CAT) could enhance DNA repairing systems and reduce level of CPD (cyclobutane pyrimidine dimers) and 6-4PP ((6-4) pyrimidine-pyrimidone photoproducts), and whether the immobilization on gold (AuNPs) and silver (AgNPs) nanoparticles affects the outcome. The study presents secondary analysis of our previous research. Three-day application of SOD and CAT in all forms of solution decreased the levels of CPD and 6-4PP boosted by UV irradiation. The mRNA expression level of the nucleotide excision repair (NER) system genes (XPA, XPC, ERCC1, ERCC2, ERCC3, LIG1) increased after application of immobilized and free enzymes. Increased by UV irradiation, p53 mRNA expression level normalized with the enzyme application. In conclusion, application of free and immobilized antioxidant enzymes accelerates removal of harmful effects of UV radiation in the rat skin by increasing expression level of NER genes.

Effects of folate-conjugated Fe2O3@Au core-shell nanoparticles on oxidative stress markers, DNA damage, and histopathological characteristics: evidence from in vitro and in vivo studies

The aim of this work was to assess the cytotoxicity, genotoxicity, and histopathological effects of Fe2O3@Au-FA NPs using in vitro and in vivo models. Cytotoxicity and cellular uptake of nanoparticles (NPs) by HUVECs were examined via 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and inductively coupled plasma-mass-spectrometry (ICP-MS). This safe dose was then used for cytotoxicity assays, including total protein, total antioxidant capacity, lipid peroxidation, cell membrane integrity, reactive oxygen species, enzyme activity, and DNA damage. In the animal model, 32 Wistar rats were randomly categorized into 4 groups and received intraperitoneal injections of NPs. Blood samples for biochemical properties and histopathological changes were investigated. MTT results indicated 20 μg/ml as the safe dose for NPs. According to ICP-MS, treated cells showed significantly higher levels of the intracellular content of Fe (p < 0.001) and Au (p < 0.01) compared with the control group. In vitro tests did not show any significant cytotoxicity or genotoxicity at the safe dose of NPs. We found no significant elevation in intracellular γ-H2AX levels after treatment of HUVEC cells with Fe2O3@Au core-shell NPs (P > 0.05). As for the in vivo analysis, we observed no marked difference in serum biochemical parameters of rats treated with 50 mg/kg and 100 mg/kg doses of our NPs. Histopathological assessments indicated that liver, kidney, and testis tissues were not significantly affected at 50 mg/kg (liver), 50 mg/kg, and 100 mg/kg (kidney and testis) on NPs administration. These findings imply that the nanotoxicity of Fe2O3@Au-FA NPs in HUVECs and animals depends largely on the administrated dose. Our study suggests that Fe2O3@Au-FA NPs at a safe dose could be considered as new candidates in nanobiomedicine.

Versatile Gold-Coupled Te-Carbon Dots for Quantitative Monitoring and Efficient Scavenging of Superoxide Anions

The superoxide anion (O₂^•-) is a reactive oxygen species (ROS) that functions as an important regulator of signal transduction in living systems. However, excess O₂^•- can cause metabolic imbalances and oxidative damage inside cells. Quantitative detection and efficient scavenging of O₂^•- are therefore critical for maintaining intracellular redox balance and homeostasis. In this work, a nanomaterial (Au-TeCD) composed of BSA-modified gold nanoparticles (AuNPs) complexed with tellurium-containing carbon dots (TeCDs) was constructed. The introduction of Au-TeCDs to solutions containing superoxide resulted in enhanced elimination of the anion, indicating that Au-TeCDs are able to scavenge O₂^•- from the surrounding environment. Notably, the respective TeCD and AuNP components of the Au-TeCDs were found to emit fluorescence at 425 and 640 nm upon exposure to superoxide anions. This unique spectroscopic property of Au-TeCDs allowed levels of O₂^•- in solution to be quantified using dual-fluorescence detection. The Au-TeCDs developed herein also exhibited low-cytotoxicity, versatile capabilities for in situ fluorescence imaging, and effective scavenging of O₂^•- in living cells. Taken together, these results suggest that Au-TeCDs act as effective tools for monitoring superoxide concentrations in complex mixtures and may be developed as possible therapeutics designed to scavenge excess ROS from diseased cells.

Trends in the development of innovative nanobiocatalysts and their application in biocatalytic transformations

The ever-growing demand for cost-effective and innocuous biocatalytic transformations has prompted the rational design and development of robust biocatalytic tools. Enzyme immobilization technology lies in the formation of cooperative interactions between the tailored surface of the support and the enzyme of choice, which result in the fabrication of tremendous biocatalytic tools with desirable properties, complying with the current demands even on an industrial level. Different nanoscale materials (organic, inorganic, and green) have attracted great attention as immobilization matrices for single or multi-enzymatic systems. Aiming to unveil the potentialities of nanobiocatalytic systems, we present distinct immobilization strategies and give a thorough insight into the effect of nanosupports specific properties on the biocatalysts' structure and catalytic performance. We also highlight the development of nanobiocatalysts for their incorporation in cascade enzymatic processes and various types of batch and continuous-flow reactor systems. Remarkable emphasis is given on the application of such nanobiocatalytic tools in several biocatalytic transformations including bioremediation processes, biofuel production, and synthesis of bioactive compounds and fine chemicals for the food and pharmaceutical industry.

The effect of immobilized antioxidant enzymes on the oxidative stress in UV-irradiated rat skin

Aim: Superoxide dismutase (SOD) and catalase (CAT) immobilized on gold nanoparticles (AuNP) and silver nanoparticles (AgNP) nanoparticles were used to reduce UV radiation-induced oxidative stress in rat skin. Materials & methods: The antioxidant influence of the enzymes was investigated on level of malondialdehyde, 8-hydroksy-2'deoksyguanozine, myeloperoxidase, total antioxidant capacity, SOD2 and CAT activity and expression, and glutathione and glutathione peroxidase activity. Results: The application of immobilized SOD and CAT on UV-irradiated skin reduced malondialdehyde and 8-hydroksy-2'deoksyguanozine levels also SOD and CAT activity and expression increased. The tested enzymes influence glutathione peroxidase activity and level of total antioxidant capacity and glutathione. Conclusion: Immobilized enzymes increased the antioxidative potential of skin following UV irradiation.

Synthesis, Structure, and Anticancer Activity of Symmetrical and Non-symmetrical Silver(I)-N-Heterocyclic Carbene Complexes

Synthesis and anticancer studies of three symmetrically and non-symmetrically substituted silver(I)-N-Heterocyclic carbene complexes of type [(NHC)₂-Ag]PF₆ (7-9) and their respective (ligands) benzimidazolium salts (4-6) are described herein. Compound 5 and Ag-NHC-complex 7 were characterized by the single crystal X-ray diffraction technique. Structural studies for 7 showed that the silver(I) center has linear C-Ag-C coordination geometry (180.00(10)^o). Other azolium and Ag-NHC analogues were confirmed by H¹ and C¹³-NMR spectroscopy. The synthesized analogues were biologically characterized for in vitro anticancer activity against three cancer cell lines including human colorectal cancer (HCT 116), breast cancer (MCF-7), and erythromyeloblastoid leukemia (K-562) cell lines and in terms of in vivo acute oral toxicity (IAOT) in view of agility and body weight of female rats. In vitro anticancer activity showed the values of IC₅₀ in range 0.31-17.9 μM in case of K-562 and HCT-116 cancer cell lines and 15.1-35.2 μM in case of MCF-7 while taking commercially known anticancer agents 5-fluorouracil, tamoxifen, and betulinic acid which have IC₅₀ values 5.2, 5.5, and 17.0 μM, respectively. In vivo study revealed vigor and agility of all test animals which explores the biocompatibility and non-toxicity of the test analogues.

Facile synthesis of SnO2shell followed by microwave treatment for high environmental stability of Ag nanoparticles

This study describes a new method for passivating Ag nanoparticles (AgNPs) with SnO₂ layer and their further treatment by microwave irradiation. The one-step process of SnO₂ layer formation was carried out by adding sodium stannate to the boiling aqueous AgNPs solution, which resulted in the formation of core@shell Ag@SnO₂ nanoparticles. The coating formation was a tunable process, making it possible to obtain an SnO₂ layer thickness in the range from 2 to 13 nm. The morphology, size, zeta-potential, and optical properties of the Ag@SnO₂NPs were studied. The microwave irradiation significantly improved the environmental resistance of Ag@SnO₂NPs, which remained stable in different biological solutions such as NaCl at 150 mM and 0.1 M, Tris-buffered saline buffer at 0.1 M, and phosphate buffer at pH 5.6, 7.0, and 8.0. Ag@SnO₂NPs after microwave irradiation were also stable at biologically relevant pH values, both highly acidic (1.4) and alkaline (13.2). Moreover, AgNPs covered with a 13 nm-thick SnO₂ layer were resistant to cyanide up to 0.1 wt%. The microwave-treated SnO₂ shell can facilitate the introduction of AgNPs in various solutions and extend their potential application in biological environments by protecting the metal nanostructures from dissolution and aggregation.

This study describes a new method for passivating Ag nanoparticles (AgNPs) with SnO₂ layer and their further treatment by microwave irradiation.