Preparation of enzyme nanoparticles and studying the catalytic activity of the immobilized nanoparticles on polyethylene films

Functionalized maghemite superparamagnetic iron oxide nanoparticles (γ-Fe2O3-SPIONs)-amylase enzyme hybrid in biofuel production

The current study describes a straightforward, biologically and environmentally friendly method for creating magnetic iron oxide (γ-Fe₂O₃) nanoparticles. We report here that the Bacillus subtilis SE05 strain, isolated from offshore formation water near Zaafarana, the Red Sea, Hurghada, Egypt, can produce highly magnetic iron oxide nanoparticles of the maghemite type (γ-Fe₂O₃). To the best of our knowledge, the ability of this bacterium to reduce Fe₂O₃ has yet to be demonstrated. As a result, this study reports on the fabrication of enzyme-NPs and the biological immobilization of α-amylase on a solid support. The identified strain was deposited in GenBank with accession number MT422787. The bacterial cells used for the synthesis of magnetic nanoparticles produced about 15.2 g of dry weight, which is considered a high quantity compared to the previous studies. The XRD pattern revealed the crystalline cubic spinel structure of γ-Fe₂O₃. TEM micrographs showed the spherically shaped IONPs had an average size of 7.68 nm. Further, the importance of protein-SPION interaction and the successful synthesis of stabilized SPIONs in the amylase enzyme hybrid system are also mentioned. The system showed the applicability of these nanomaterials in biofuel production, which demonstrated significant production (54%) compared to the free amylase enzyme (22%). Thus, it is predicted that these nanoparticles can be used in energy fields.

Fabrication and Characterization of Dextranase Nano-Entrapped Enzymes in Polymeric Particles Using a Novel Ultrasonication–Microwave Approach

In the current study, a novel method to improve the nano-entrapment of enzymes into Ca-alginate gel was investigated to determine the synergistic effects of ultrasound combined with microwave shock (UMS). The effects of UMS treatment on dextranase enzymes’ loading effectiveness (LE) and immobilization yield (IY) were investigated. By using FT-IR spectra and SEM, the microstructure of the immobilized enzyme (IE) was characterized. Additionally, the free enzyme was used as a control to compare the reusability and enzyme-kinetics characteristics of IEs produced with and without UMS treatments. The results demonstrated that the highest LE and IY were obtained when the IE was produced with a US of 40 W at 25 kHz for 15 min combined with an MS of 60 W at a shock rate of 20 s/min for 20 min, increasing the LE and the IY by 97.32 and 78.25%, respectively, when compared with an immobilized enzyme prepared without UMS treatment. In comparison with the control, UMS treatment dramatically raised the Vmax, KM, catalytic, and specificity constant values for the IE. The outcomes suggested that a microwave shock and ultrasound combination would be an efficient way to improve the immobilization of enzymes in biopolymer gel.

Polymer/Enzyme Composite Materials—Versatile Catalysts with Multiple Applications

A significant interest was granted lately to enzymes, which are versatile catalysts characterized by natural origin, with high specificity and selectivity for particular substrates. Additionally, some enzymes are involved in the production of high-valuable products, such as antibiotics, while others are known for their ability to transform emerging contaminates, such as dyes and pesticides, to simpler molecules with a lower environmental impact. Nevertheless, the use of enzymes in industrial applications is limited by their reduced stability in extreme conditions and by their difficult recovery and reusability. Rationally, enzyme immobilization on organic or inorganic matrices proved to be one of the most successful innovative approaches to increase the stability of enzymatic catalysts. By the immobilization of enzymes on support materials, composite biocatalysts are obtained that pose an improved stability, preserving the enzymatic activity and some of the support material’s properties. Of high interest are the polymer/enzyme composites, which are obtained by the chemical or physical attachment of enzymes on polymer matrices. This review highlights some of the latest findings in the field of polymer/enzyme composites, classified according to the morphology of the resulting materials, following their most important applications.

Peptide conformational imprints enhanced the catalytic activity of papain for esterification

Peptide conformational imprints (PCIs) offer a promising perspective to directly generate binding sites for preserving enzymes with high catalytic activity and stability. In this study, we synthesized a new chiral cross-linker cost-effectively for controlling the matrix morphology of PCIs on magnetic particles (PCIMPs) to stabilize their recognition capability. Meanwhile, based on the flank part of the sequences on papain (PAP), three epitope peptides were selected and synthesized. Molecularly imprinted polymers (MIPs) were then fabricated in the presence of the epitope peptide using our new cross-linker on magnetic particles (MPs) to generate PCIMPs. PCIMPs were formed with helical cavities that complement the PAP structure to adsorb specifically at the targeted position of PAP. PCIMPs^65–79 were found to have the best binding parameters to the PAP with K_d = 0.087 μM and B_max = 4.56 μM. Upon esterification of N-Boc-His-OH, proton nuclear magnetic resonance (¹H-NMR) was used to monitor the yield of the reaction and evaluate the activity of PAP/PCIMPs. The kinetic parameters of PAP/PCIMPs^65–79 were calculated as V_max = 3.0 μM s⁻¹, K_m = 5 × 10⁻² M, k_cat = 1.1 × 10^–1 s⁻¹, and k_cat/K_m = 2.2 M⁻¹ s⁻¹. In addition, PAP is bound tightly to PCIMPs to sustain its activity after four consecutive cycles.

Synthesis, characterization and immobilization of bilirubin oxidase nanoparticles (BOxNPs) with enhanced activity: Application for serum bilirubin determination in jaundice patients

A high- power ultrasonic method was used to prepare bilirubin oxidase nanoparticles (BOxNPs) which were immobilized on polyethylene (PE) film. The characterization of PE film bound to BOxNPs and BOxNPs was carried out using "Dynamic Light Scattering (DLS)," "Transmission Electron Microscopy (TEM)," and "Scanning Electron Microscopy (SEM)." The PE film was treated with nitric acid (HNO₃) for its activation. BOxNPs bound to PE film exhibited optimal activity (pH-8), incubation time (11 s) with temperature 35 °C. A linear relationship was observed between the bilirubin concentrations (0.02-250 μM), with an apparent Km value and Vmax for PE- bound BOxNPs, at 0.015 μM and 2.56 μmol/mL/min. The mean recoveries of added serum bilirubin were 94.5 % at a level of 5 mM whereas 98.5 % were observed at 10 mM which showed the satisfactory reliability of BOxNPs immobilized on PE film. The coefficient of variation for serum bilirubin ranged between 4.52%-5.25%, measured on the first day (within batch) and after seven days of storage (between batch).This current method has showed a good correlation for bilirubin values when compared to the standard enzymatic colorimetric method using free enzyme. BOxNPs bound to PE film were reutilized 150 times with storage at 4 °C for 120 days.

Use of A Hydroalcoholic Extract of Moringa oleifera Leaves for the Green Synthesis of Bismuth Nanoparticles and Evaluation of Their Anti-Microbial and Antioxidant Activities

The employment of plant extracts in the synthesis of metal nanoparticles is a very attractive approach in the field of green synthesis. To benefit from the potential synergy between the biological activities of the Moringa oleifera and metallic bismuth, our study aimed to achieve a green synthesis of phytochemical encapsulated bismuth nanoparticles using a hydroalcoholic extract of M. oleifera leaves. The total phenolic content in the M. oleifera leaves extract used was 23.0 ± 0.3 mg gallic acid equivalent/g of dried M. oleifera leaves powder. The physical properties of the synthesized bismuth nanoparticles were characterized using UV-Vis spectrophotometer, FT-IR spectrometer, TEM, SEM, and XRD. The size of the synthesized bismuth nanoparticles is in the range of 40.4-57.8 nm with amorphous morphology. Using DPPH and phosphomolybdate assays, our findings revealed that the M. oleifera leaves extract and the synthesized bismuth nanoparticles possess antioxidant properties. Using resazurin microtiter assay, we also demonstrate that the M. oleifera leaves extract and the synthesized bismuth nanoparticles exert potent anti-bacterial activity against Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, and Enterococcus faecalis (estimated MIC values for the extract: 500, 250, 250, and 250 µg/mL; estimated MIC values for the bismuth nanoparticles: 500, 500, 500, and 250 µg/mL, respectively). Similarly, the M. oleifera leaves extract and the synthesized bismuth nanoparticles display relatively stronger anti-fungal activity against Aspergillus niger, Aspergillus flavus, Candida albicans, and Candida glabrata (estimated MIC values for the extract: 62.5, 62.5, 125, and 250 µg/mL; estimated MIC values for the bismuth nanoparticles: 250, 250, 62.5, and 62.5 µg/mL, respectively). Thus, green synthesis of bismuth nanoparticles using M. oleifera leaves extract was successful, showing a positive antioxidant, anti-bacterial, and anti-fungal activity. Therefore, the synthesized bismuth nanoparticles can potentially be employed in the alleviation of symptoms associated with oxidative stress and in the topic treatment of Candida infections.

Green Synthesis of Encapsulated Copper Nanoparticles Using a Hydroalcoholic Extract of Moringa oleifera Leaves and Assessment of Their Antioxidant and Antimicrobial Activities

: The synthesis of metal nanoparticles using plant extracts is a very promising method in green synthesis. The medicinal value of Moringa oleifera leaves and the antimicrobial activity of metallic copper were combined in the present study to synthesize copper nanoparticles having a desirable added-value inorganic material. The use of a hydroalcoholic extract of M. oleifera leaves for the green synthesis of copper nanoparticles is an attractive method as it leads to the production of harmless chemicals and reduces waste. The total phenolic content in the M. oleifera leaves extract was 23.0 ± 0.3 mg gallic acid equivalent/g of dried M. oleifera leaves powder. The M. oleifera leaves extract was treated with a copper sulphate solution. A color change from brown to black indicates the formation of copper nanoparticles. Characterization of the synthesized copper nanoparticles was performed using ultraviolet-visible light (UV-Vis) spectrophotometry, Fourier-transform infrared (FTIR) spectrometry, high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The synthesized copper nanoparticles have an amorphous nature and particle size of 35.8-49.2 nm. We demonstrate that the M. oleifera leaves extract and the synthesized copper nanoparticles display considerable antioxidant activity. Moreover, the M. oleifera leaves extract and the synthesized copper nanoparticles exert considerable anti-bacterial activity against Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, and Enterococcus faecalis (MIC values for the extract: 500, 250, 250, and 250 µg/mL; MIC values for the copper nanoparticles: 500, 500, 500, and 250 µg/mL, respectively). Similarly, the M. oleifera leaves extract and the synthesized copper nanoparticles exert relatively stronger anti-fungal activity against Aspergillus niger, Aspergillus flavus, Candida albicans, and Candida glabrata (MIC values for the extract: 62.5, 62.5, 125, and 250 µg/mL; MIC values for the copper nanoparticles: 125, 125, 62.5, and 31.2 µg/mL, respectively). Our study reveals that the green synthesis of copper nanoparticles using a hydroalcoholic extract of M. oleifera leaves was successful. In addition, the synthesized copper nanoparticles can be potentially employed in the treatment of various microbial infections due to their reported antioxidant, anti-bacterial, and anti-fungal activities.

A facile method for the deposition of volatile natural compound-based nanoparticles on biodegradable polymer surfaces

In the current work, stable nanoparticles (NPs) of vanillin are formed in situ from an aqueous/ethanol solution and deposited on the surface of chitosan, a natural polymer, using a high-intensity ultrasonic method.

Sonochemical fabrication of edible fragrant antimicrobial nano coating on textiles and polypropylene cups

We report on a simple and effective ultrasound-assisted deposition of vanillin nanoparticles (∼50nm in size), raspberry ketone (RK) nanoparticles (∼40nm in size) and camphor nanoparticles (width ∼30nm, length ∼40nm in size) on textiles and on polypropylene surfaces. The excellent antibacterial and antifungal activity of the fragrant coatings on cotton bandages, and polypropylene surface against Escherichia coli (E. coli), Salmonella paratyphi A (S. paratyphi A) and the yeast Candida albicans (C. albicans) cultures was demonstrated. It is worth pointing out that these fragrant materials are edible, making them very useful for packaging. The mechanism of the edible fragrant coating formation and adhesion to the textile was discussed, and finally an up-scaling of the sonochemical process for textile coating was carried out.

Influence of chitosan-sodium alginate pretreated with ultrasound on the enzyme activity, viscosity and structure of papain

BACKGROUND

Ultrasound treatment has been shown to be an effective technique for improving the activity of immobilized enzymes. However, its mechanism is unclear.

RESULTS

The effect of ultrasonic pretreated chitosan-sodium alginate (CHI-ALG) on the enzymatic activity of papain was investigated via a single factor (temperature, time, frequency, power) experiment. The maximum relative enzyme activity of papain was observed when it was mixed with ultrasound pretreated CHI-ALG at 135 kHz, 0.25 W cm^-2 and 50 °C for 20 min, during which the relative activity increased by 72.14% compared to untreated CHI-ALG. Viscosity analysis of papain mixed with CHI-ALG pretreated and untreated with ultrasound revealed that stronger association interactions between the polymers were formed compared to the untreated sample. Fluorescence and circular dichroism spectra indicated that the ultrasonic pretreatment of CHI-ALG increased the number of tryptophan on the papain surface and also increased the content of α-helix by 6.97% and decreased the content of β-sheet by 3.45% compared to the untreated solution.

CONCLUSION

The results of the present study indicate that papain combined with CHI-ALG pretreated with the appropriate ultrasound could be effective technique for improving the activity of immobilized enzymes as a result of changes in its structure and intermolecular interactions. It is important to extend the application of CHI-ALG gel in the immobilized enzyme industry. © 2016 Society of Chemical Industry.

Anti-Bacterial and Anti-Fungal Activity of Xanthones Obtained via Semi-Synthetic Modification of α-Mangostin from Garcinia mangostana

The microbial contamination in food packaging has been a major concern that has paved the way to search for novel, natural anti-microbial agents, such as modified α-mangostin. In the present study, twelve synthetic analogs were obtained through semi-synthetic modification of α-mangostin by Ritter reaction, reduction by palladium-carbon (Pd-C), alkylation, and acetylation. The evaluation of the anti-microbial potential of the synthetic analogs showed higher bactericidal activity than the parent molecule. The anti-microbial studies proved that I E showed high anti-bacterial activity whereas I I showed the highest anti-fungal activity. Due to their microbicidal potential, modified α-mangostin derivatives could be utilized as active anti-microbial agents in materials for the biomedical and food industry.

One-step surface grafting of organic nanoparticles: in situ deposition of antimicrobial agents vanillin and chitosan on polyethylene packaging films

Natural organic molecules, volatile vanillin and non-volatile chitosan, were deposited from solution onto a polyethylene surface by the ultrasonic method and demonstrate specific antimicrobial activity.

Enhanced pharmacological activity of vitamin B₁₂ and penicillin as nanoparticles

Sonochemistry has become a well-known technique for fabricating nanomaterials. Since one of the advantages of nanomaterials is that they have higher chemical activities compared with particles in the bulk form, efforts are being made to produce nano organic compounds with enhanced biological activities that could be exploited in the medical area. This study uses the sonication technique to prepare nano Vitamin B12 and nano Penicillin, and demonstrates their enhanced biological and pharmacological activity. The size and morphology of the nano Penicillin and nano Vitamin B12 were investigated using electron microscopy as well as dynamic light scattering techniques. The sizes of Penicillin and Vitamin B12 nanoparticles (NPs) were found to be 70 and 120-180 nm, respectively. The bactericidal effect of nano Penicillin was studied and found to be higher than that of the bulk form. Reducing the size of Vitamin B12 resulted in their enhanced antioxidative activity as observed using the electron paramagnetic spectroscopy technique. The penetration depth of these organic NPs can be detected by an optical iterative method. It is believed that nano organic drugs fabrication will have a great impact on the medical field.

New life for an old antibiotic

Restoring the antibacterial properties of existing antibiotics is of great concern. Herein, we present, for the first time, the formation and deposition of stable antibiotic nanoparticles (NPs) on graphene oxide (GO) sheets by a facile one-step sonochemical technique. Sonochemically synthesized graphene oxide/tetracycline (GO/TET) composite shows enhanced activity against both sensitive and resistant Staphylococcus aureus (S. aureus). The size and deposition of tetracycline (TET) nanoparticles on GO can be controlled by varying the sonication time. The synthesized NPs ranged from 21 to 180 nm. Moreover, ultrasonic irradiation does not cause any structural and chemical changes to the TET molecule as confirmed by Fourier transform infrared spectroscopy (FTIR). The virtue of π-π stacking between GO and TET additionally facilitate the coating of TET NPs upon GO. A time dependent release kinetics of TET NPs from the GO surface is also monitored providing important insights regarding the mechanism of antibacterial activity of GO/TET composites. Our results show that the GO/TET composite is bactericidal in nature, resulting in similar values of minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). This composite is found to be active against TET resistant S. aureus at a concentration four times lower than the pristine TET. The sensitive S. aureus follows the same trend showing six times lower MIC values compared to pristine TET. GO shows no activity against both sensitive and resistant S. aureus even at a concentration as high as 1 mg/mL but influences the biocidal activity of the GO/TET composite. We propose that the unique structure and composition manifested by GO/TET composites may be further utilized for different formulations of antibiotics with GO. The sonochemical method used in this work can be precisely tailored for the stable deposition of a variety of antibiotics on the GO surface to reduce health risks and increase the spectrum of applications.

Tetracycline nanoparticles as antibacterial and gene-silencing agents

The spread of antibiotic-resistant bacteria and parasites calls for the development of new therapeutic strategies with could potentially reverse this trend. Here, a proposal is presented to exploit a sonochemical method to restore the antibiotic activity of tetracycline (TTCL) against resistant bacteria by converting the antibiotic into a nanoparticulate form. The demonstrated sonochemical method allows nanoscale TTCL assembly to be driven by supramolecular hydrogen bond formation, with no further modification to the antibiotic's chemical structure. It is shown that tetracycline nanoparticles (TTCL NPs) can act as antibacterial agents, both against TTCL sensitive and against resistant bacterial strains. Moreover, the synthesized antibiotic nanoparticles (NPs) can act as effective gene-silencing agents through the use of a TTCL repressor in Trypanosome brucei parasites. It is demonstrated that the NPs are nontoxic to human cells and T. brucei parasites and are able to release their monomer components in an active form in a manner that results in enhanced antimicrobial activity relative to a homogeneous solution of the precursor monomer. As the TTCL NPs are biocompatible and biodegradable, sonochemical formation of TTCL NPs represents a new promising approach for generation of pharmaceutically active nanomaterials.

Ultrasound coating of polydimethylsiloxanes with antimicrobial enzymes

Enzyme cellobiose dehydrogenase (CDH) nanoparticles were created by the ultrasonic waves and subsequently deposited on the PDMS surface. PDMS sheets treated for 3 min significantly reduce the amount of viableS. aureuscells as well as the total amount of biomass deposited on the surface.

Antibiotic nanoparticles embedded into the Parylene C layer as a new method to prevent medical device-associated infections

Tetracycline nanoparticles (NPs) were synthesized and simultaneously deposited on Parylene-C coated glass slides using ultrasound irradiation.

Combined of ultrasound irradiation with high hydrostatic pressure (US/HHP) as a new method to improve immobilization of dextranase onto alginate gel

In this research work, dextranase was immobilized onto calcium alginate beads by the combination of ultrasonic irradiation and high hydrostatic pressure (US/HHP) treatments. Effects of US/HHP treatments on loading efficiency and immobilization yield of dextranase enzyme onto calcium alginate beads were investigated. Furthermore, the activities of immobilized enzymes prepared with and without US/HHP treatments and that prepared with ultrasonic irradiation (US) and high hydrostatic pressure (HHP), as a function of pH, temperature, recyclability and enzyme kinetic parameters, were compared with that for free enzyme. The maximum loading efficiency and the immobilization yield were observed when the immobilized dextranase was prepared with US (40 W at 25 kHz for 15 min) combined with HHP (400 MPa for 15 min), under which the loading efficiency and the immobilization yield increased by 88.92% and 80.86%, respectively, compared to immobilized enzymes prepared without US/HHP treatment. On the other hand, immobilized enzyme prepared with US/HHP treatment showed Vmax, KM, catalytic and specificity constants values higher than that for the immobilized enzyme prepared with HHP treatment, indicated that, this new US/HHP method improved the catalytic kinetics activity of immobilized dextranase at all the reaction conditions studied. Compared to immobilized enzyme prepared either with US or HHP, the immobilized enzymes prepared with US/HHP method exhibited a higher: pH optimum, optimal reaction temperature, thermal stability and recyclability, and lower activation energy, which, illustrating the effectiveness of the US/HHP method. These results indicated that, the combination of US and HHP treatments could be an effective method for improving the immobilization of enzymes in polymers.

Ultrasound-assisted dextranase entrapment onto Ca-alginate gel beads

In this research work, dextranase has immobilized onto calcium alginate beads using a novel ultrasound method. The process of immobilization of the enzyme was carried out in a one-step ultrasound process. Effects of ultrasound conditions on loading efficiency and immobilization yield of the enzyme onto calcium alginate beads were investigated. Furthermore, the activity of the free and immobilized enzymes prepared with and without ultrasound treatment, as a function of pH, temperature, recyclability and enzyme kinetic parameters, was compared. The maximum loading efficiency and the immobilization yield were observed when the immobilized dextranase was prepared with an ultrasonic irradiation at 25 kHz, 40 W for 15 min, under which the loading efficiency and the immobilization yield increased by 27.21% and 18.77%, respectively, compared with the immobilized enzymes prepared without ultrasonic irradiation. On the other hand, immobilized enzyme prepared with ultrasonic irradiation showed Vmax and KM value higher than that for the immobilized enzyme prepared without ultrasonic irradiation, likewise, both the catalytic and specificity constants of immobilized enzyme prepared with ultrasonic irradiation were higher than that for immobilized enzyme prepared without ultrasound, indicating that, this new ultrasonic method improved the catalytic kinetics activity of immobilized dextranase at all the reaction conditions studied. Compared with immobilized enzyme prepared without ultrasound treatment, the immobilized enzymes prepared with ultrasound irradiation exhibited: a higher pH optimum, optimal reaction temperature, activation energy, and thermal stability, as well as, a higher recyclability, which, illustrating the effectiveness of the sonochemical method. To the best of our knowledge, this is the first report on the effect of ultrasound treatments on the immobilization of dextranase.