Photobiosynthesis of stable and functional silver/silver chloride nanoparticles with hydrolytic activity using hyperthermophilic β-glucosidases with industrial potential

Application of Bacillus sp. protease in the fabrication of silver/silver chloride nanoparticles in solution and cotton gauze bandages

Silver (Ag)/silver chloride (AgCl) nanoparticles have been used worldwide for their antimicrobial activity. Proteases play an important role in many physiological processes during wound healing. Therefore, the aim of this study was to fabricate silver-type nanoparticles exhibiting protease activity for medical applications such as wound healing and dressings. The Ag/AgCl nanoparticles were fabricated using Bacillus sp. protease and visible light activation. The size of the fabricated nanoparticles was estimated to be 35.29 ± 6.43 nm. The nanoparticles were coated on a cotton gauze bandage using immersion and ultrasonication. Scanning electron microscopy and energy dispersive X-ray spectroscopy confirmed that the nanoparticles could be used to coat the gauze bandage. Synchrotron radiation X-ray tomographic microscopy indicated that coating with the nanoparticles did not destroy the packing of cotton fibers in the gauze bandage. The nanoparticles exhibited fibrinolytic and collagenolytic activities. Protease activity remained after the nanoparticle coating was applied to the gauze bandage. The nanoparticles were not absorbed on a gelatin agar plate after incubation at 37 °C for 18 H. These results suggest that the coated cotton gauze bandage may be safe for further use, and the nanoparticles may not be absorbed into animal or human skin.

Increased Stability of Oligopeptidases Immobilized on Gold Nanoparticles

The metallopeptidases thimet oligopeptidase (THOP, EC 3.4.24.25) and neurolysin (NEL, EC 3.4.24.26) are enzymes that belong to the zinc endopeptidase M13 family. Numerous studies suggest that these peptidases participate in the processing of bioactive peptides such as angiotensins and bradykinin. Efforts have been conducted to develop biotechnological tools to make possible the use of both proteases to regulate blood pressure in mice, mainly limited by the low plasmatic stability of the enzymes. In the present study, it was investigated the use of nanotechnology as an efficient strategy for to circumvent the low stability of the proteases. Recombinant THOP and NEL were immobilized in gold nanoparticles (GNPs) synthesized in situ using HEPES and the enzymes as reducing and stabilizing agents. The formation of rTHOP-GNP and rNEL-GNP was characterized by the surface plasmon resonance band, zeta potential and atomic force microscopy. The gain of structural stability and activity of rTHOP and rNEL immobilized on GNPs was demonstrated by assays using fluorogenic substrates. The enzymes were also efficiently immobilized on GNPs fabricated with sodium borohydride. The efficient immobilization of the oligopeptidases in gold nanoparticles with gain of stability may facilitate the use of the enzymes in therapies related to pressure regulation and stroke, and as a tool for studying the physiological and pathological roles of both proteases.

Green construction of recyclable amino-tannic acid modified magnetic nanoparticles: Application for β-glucosidase immobilization

The β-glucosidase (BGL) enzyme in food industry is great interest due to its role in food conversion to produce functional food products. In this study, the BGL was covalently immobilized onto amino-tannic acid modified Fe₃O₄ magnetic nanoparticles (ATA-Fe₃O₄ MNPs) as biocompatible nanoplatform by modified poly-aldehyde pullulan (PAP) as a cross-linker to enhance the ability and strength of the nanoparticle connection to the enzyme. The properties of support were subsequently characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The highest percentage of loading and immobilization yield was obtained with 0.1 mg enzyme/mL citrate buffer (pH 6, 1 M) enzyme solution, carrier solution of 10 mg ATA-Fe₃O₄/3 mL citrate buffer (pH 6, 1 M), and PAP solution of 20% total reaction system volume. Optimum pH and temperature were found for free (pH 5.0 and temperature 30 °C) and immobilized (pH 6.0 and temperature 40 °C) enzyme. The immobilized BGL maintains its activity to 83% after 10 cycles. Therefore, immobilization of BGL by this method is an efficient procedure to improve the properties of enzyme.

Nanobiohybrids: a new concept for metal nanoparticles synthesis

In recent years, nanoscience and nanotechnology have brought a great revolution in different areas. In particular, the synthesis of transition metal nanoparticles has been of great relevance for their use in areas such as biomedicine, antimicrobial properties or catalytic applications for chemical synthesis. Recently, an innovative straightforward and very efficient synthesis of these nanoparticles by simply using enzymes as inductors in aqueous media has been described. This represents a very green alternative to the different methodologies described in the literature for metal nanoparticles preparation where harsh conditions are necessary. In this review the most recent advances in the synthesis of metal nanoparticles by this green technology, explaining the synthetic mechanism, the role of the enzyme in the formation of the nanoparticles and the effect on the final properties of these nanoparticles, are summarised. The application of these novel metal nanoparticles-enzyme hybrids in synthetic chemistry as heterogeneous catalysts with metal or dual (enzymatic and metallic) activity and their capacity as environmental and antimicrobial agents have also been discussed.

Fabrication of silver chloride nanoparticles using a plant serine protease in combination with photoactivation and investigation of their biological activities

Recently, the development of "green" methods for fabrication of silver nanoparticles (Ag-NPs) has been emphasized, in view of their environmental safety, feasibility, and low cost. In this study, a serine protease, EuP-82 from Euphorbia cf. lactea latex, was used to fabricate silver chloride nanoparticles (AgCl-NPs) in phosphate-buffered saline (pH 7.2), under the influence of visible light. The fabricated nanoparticles had a maximal surface plasmon resonance absorption peak at 435 nm. The size of the AgCl-NPs, estimated by scanning electron microscopy, was 57 ± 14.7 nm. Energy dispersive X-ray spectroscopy, X-ray absorption spectroscopy, and X-ray diffraction analysis confirmed that the fabricated Ag-NPs were of the AgCl type. The fabricated nanoparticles had antioxidant activity, scavenging DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals with IC₅₀ of 204 ± 1.8 μg/mL. The fabricated AgCl-NPs had broad-spectrum in vitro antimicrobial activities, acting against the Gram-positive bacteria Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), and Bacillus cereus, and the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa. AgCl-NPs also showed antifungal activity against Candida albicans and C. tropicalis. In addition, AgCl-NPs showed antiprotozoal activity against Giardia lamblia, with IC₅₀ 202 ± 2.1 μg/mL. Based on the biological activities of the fabricated AgCl-NPs, they have the potential for widespread application in medicine and industry.