Synthesis of Protein-Inorganic Nanohybrids with Improved Catalytic Properties Using Co3(PO4)2

Immobilization of collagenase in inorganic hybrid nanoflowers with enhanced stability, proteolytic activity, and their anti-amyloid potential

Organic-inorganic hybrid nanomaterials are considered as promising immobilization matrix for enzymes owing to their markedly enhanced stability and reusability. Herein, collagenase was chosen as a model enzyme to synthesize collagenase hybrid nanoflowers (Col-hNFs). Maximum collagenase activity (155.58 μmol min-1 L-1) and encapsulation yield (90 %) were observed in presence of Zn(II) ions at 0.05 mg/mL collagenase, 120 mM zinc chloride and PBS (pH 7.5). Synthesized Col-Zn-hNFs were extensively characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), Fourier transform infrared (FTIR), circular dichroism (CD), fluorescence spectroscopy, dynamic light scattering (DLS) and zeta potential measurements. SEM images showed flower-like morphology with average size of 5.1 μm and zeta potential of -14.3 mV. Col-Zn-hNFs demonstrated superior relative activity across wide pH and temperature ranges, presence of organic solvents and surfactants as compared to its free form. Moreover, Col-Zn-hNFs exhibited excellent shelf life stability and favorable reusability. Col-Zn-hNFs showed the ability to suppress and eradicate fully developed insulin fibrils in vitro (IC50 = 2.8 and 6.2 μg/mL, respectively). This indicates a promising inhibitory potential of Col-Zn-hNFs against insulin amyloid fibrillation. The findings suggest that the utilization of Col-Zn-hNFs as a carrier matrix holds immense potential for immobilizing collagenase with improved catalytic properties and biomedical applications.

Enzymatic dual-faced Janus structures based on the hierarchical organic-inorganic hybrid matrix for an effective bioremoval and detoxification of reactive blue-19

A novel, dual-faced, and hierarchical type of Janus hybrid structures (JHSs) was assembled through an in situ growing of lipase@cobalt phosphate sheets on the laccase@copper phosphate sponge-like structures. The chemical and structural information of prepared JHSs was investigated by Scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray diffraction analysis (XRD). The catalytic activity, storage stability, and reusability of JHSs were then investigated. The SEM-EDX analysis clearly confirmed the asymmetric morphology of the fabricated JHSs with two distinct metal distributions. Under optimized synthesis conditions, the prepared JHSs showed 97.8 % and 100 % of laccase and lipase activity, respectively. Compared to the free biocatalysts, the immobilization resulted in ~ a 2-fold increase in laccase and lipase stability at temperatures of >40 °C. The fabricated JHSs maintained 61 % and 90 % of their original laccase and lipase activity upon 12 successive repetition cycles. Up to 80 % of Reactive Blue-19 (RB-19), an anthraquinone-based vinyl sulphone dye, was removed after 5 h treatment with the prepared JHSs (50 % higher than the free forms of laccase and lipase). The dye removal data fitted very well on the pseudo-second-order kinetic model with a rate constant of 0.8 g mg-1 h-1. Following the bioremoval process, bacterial toxicity also decreased by about 70 %. Therefore, the prepared JHSs provide a facile and sustainable approach for the decolorization, biotransformation, and detoxification of RB-19 by integrating enzymatic oxidation and hydrolysis.

Emerging Field of Nanotechnology in Environment

The art of utilizing and manipulating micro materials have been dated back to antient era. With the advancement in technologies, the state-of-art methods of nano technologies and nano sciences has been employed in various sectors including environment, product designing, food industry, pharmaceuticals industries to way out solve standard problem of mankind. Due to rapid industrialization and the alarming levels of pollution there has been an urgent need to address the environmental and energy issues. Environmental sustainability concerns the global climate change and pollution including air, water, soil. The field of nanotechnology has proven to be a promising field where sensing and remediation, have been dramatically advanced by the use of nanomaterials. This emergent science of surface to mass ratio is the principle theorem for manipulating structure at molecular levels. The review sums up all the advancements in the field of nanotechnology and their recent application in the environment. New opportunities and challenges have also been discussed in detail to understand the use of nanotechnology as problem-to-solution ratio.

Graphical abstract

Image depicting the application of nanotechnology in environmental concerns. The combinations of technologies like bioremediations, bioaugmentations with state-of-the-art nanotechnology like carbon nanotubes and Nano capsules to answer the environmental challenges of soil quality, and plant productivity.

Laccase Immobilization on Copper-Magnetic Nanoparticles for Efficient Bisphenol Degradation

Laccase activity is influenced by copper (Cu) as an inducer. In this study, laccase was immobilized on Cu and Cu-magnetic (Cu/Fe₂O₄) nanoparticles (NPs) to improve enzyme stability and potential applications. The Cu/Fe₂O₄ NPs functionally activated by 3-aminopropyltriethoxysilane and glutaraldehyde exhibited an immobilization yield and relative activity (RA) of 93.1 and 140%, respectively. Under optimized conditions, Cu/Fe₂O₄ NPs showed high loading of laccase up to 285 mg/g of support and maximum RA of 140% at a pH 5.0 after 24 h of incubation (4°C). Immobilized laccase, as Cu/Fe₂O₄-laccase, had a higher optimum pH (4.0) and temperature (45°C) than those of a free enzyme. The pH and temperature profiles were significantly improved through immobilization. Cu/Fe₂O₄-laccase exhibited 25-fold higher thermal stability at 65°C and retained residual activity of 91.8% after 10 cycles of reuse. The degradation of bisphenols was 3.9-fold higher with Cu/Fe₂O₄-laccase than that with the free enzyme. To the best of our knowledge, Rhus vernicifera laccase immobilization on Cu or Cu/Fe₂O₄ NPs has not yet been reported. This investigation revealed that laccase immobilization on Cu/Fe₂O₄ NPs is desirable for efficient enzyme loading and high relative activity, with remarkable bisphenol A degradation potential.

Evaluation of TiO2 Nanoparticles Physicochemical Parameters Associated with their Antimicrobial Applications

Titanium dioxide nanoparticles (TiO2NPs) usage is increasing in everyday consumer products, hence, assessing their toxic impacts on living organisms and environment is essential. Various studies have revealed the significant role of TiO2NPs physicochemical properties on their toxicity. However, TiO2NPs are still poorly characterized with respect to their physicochemical properties, and environmental factors influencing their toxicity are either ignored or are too complex to be assessed under laboratory conditions. The outcomes of these studies are diverse and inconsistent due to lack of standard protocols. TiO2NPs toxicity also differs for in vivo and in vitro systems, which must also be considered during standardization of protocols to maintain uniformity and reproducibility of results. This review critically evaluates impact of different physicochemical parameters of TiO2NPs and other experimental conditions, employed in different laboratories in determining their toxicity towards bacteria. These important observations may be helpful in evaluation of environmental risks posed by these nanoparticles and this can further assist regulatory bodies in policymaking.

Emerging trends in environmental and industrial applications of marine carbonic anhydrase: a review

Biocatalytic conversion of greenhouse gases such as carbon dioxide into commercial products is one of the promising key approaches to solve the problem of climate change. Microbial enzymes, including carbonic anhydrase, NAD-dependent formate dehydrogenase, ribulose bisphosphate carboxylase, and methane monooxygenase, have been exploited to convert atmospheric gases into industrial products. Carbonic anhydrases are Zn²⁺-dependent metalloenzymes that catalyze the reversible conversion of CO₂ into bicarbonate. They are widespread in bacteria, algae, plants, and higher organisms. In higher organisms, they regulate the physiological pH and contribute to CO₂ transport in the blood. In plants, algae, and photosynthetic bacteria carbonic anhydrases are involved in photosynthesis. Converting CO₂ into bicarbonate by carbonic anhydrases can solidify gaseous CO2, thereby reducing global warming due to the burning of fossil fuels. This review discusses the three-dimensional structures of carbonic anhydrases, their physiological role in marine life, their catalytic mechanism, the types of inhibitors, and their medicine and industry applications.

Nano-Biocatalysts: Potential Biotechnological Applications

Biocatalysts are a biomolecule of interest for various biotechnological applications. Non-reusability and poor stability of especially enzymes has always limited their applications in large-scale processing units. Nanotechnology paves a way by conjugating the biocatalysts on different matrices. It predominantly enables nanomaterials to overcome the limited efficacy of conventional biocatalysts. Nanomaterial conjugated nanobiocatalyst have enhanced catalytic properties, selectivity, and stability. Nanotechnology extended the flexibility to engineer biocatalysts for various innovative and predictive catalyses. So developed nanobiocatalyst harbors remarkable properties and has potential applications in diverse biotechnological sectors. This article summaries various developments made in the area of nanobiocatalyst towards their applications in biotechnological industries. Novel nanobiocatalyst engineering is an area of critical importance for harnessing the biotechnological potential.

Biomolecules Production from Greenhouse Gases by Methanotrophs

Harmful effects on living organisms and the environment are on the rise due to a significant increase in greenhouse gas (GHG) emissions through human activities. Therefore, various research initiatives have been carried out in several directions in relation to the utilization of GHGs via physicochemical or biological routes. An environmentally friendly approach to reduce the burden of significant emissions and their harmful effects is the bioconversion of GHGs, including methane (CH4) and carbon dioxide (CO2), into value-added products. Methanotrophs have enormous potential for the efficient biotransformation of CH4 to various bioactive molecules, including biofuels, polyhydroxyalkanoates, and fatty acids. This review highlights the recent developments in methanotroph-based systems for methanol production from GHGs and proposes future perspectives to improve process sustainability via biorefinery approaches.

Anaerobic Digestion of Agri-Food Wastes for Generating Biofuels

Presently, fossil fuels are extensively employed as major sources of energy, and their uses are considered unsustainable due to emissions of obnoxious gases on the burning of fossil fuels, which can lead to severe environmental complications, including human health. To tackle these issues, various processes are developing to waste as a feed to generate eco-friendly fuels. The biological production of fuels is considered to be more beneficial than physicochemical methods due to their environmentally friendly nature, high rate of conversion at ambient physiological conditions, and less energy-intensive. Among various biofuels, hydrogen (H₂) is considered as a wonderful due to high calorific value and generate water molecule as end product on the burning. The H₂ production from biowaste is demonstrated, and agri-food waste can be potentially used as a feedstock due to their high biodegradability over lignocellulosic-based biomass. Still, the H₂ production is uneconomical from biowaste in fuel competing market because of low yields and increased capital and operational expenses. Anaerobic digestion is widely used for waste management and the generation of value-added products. This article is highlighting the valorization of agri-food waste to biofuels in single (H₂) and two-stage bioprocesses of H₂ and CH₄ production.

Enzyme-Loaded Flower-Shaped Nanomaterials: A Versatile Platform with Biosensing, Biocatalytic, and Environmental Promise

As a result of their unique structural and multifunctional characteristics, organic-inorganic hybrid nanoflowers (hNFs), a newly developed class of flower-like, well-structured and well-oriented materials has gained significant attention. The structural attributes along with the surface-engineered functional entities of hNFs, e.g., their size, shape, surface orientation, structural integrity, stability under reactive environments, enzyme stabilizing capability, and organic-inorganic ratio, all significantly contribute to and determine their applications. Although hNFs are still in their infancy and in the early stage of robust development, the recent hike in biotechnology at large and nanotechnology in particular is making hNFs a versatile platform for constructing enzyme-loaded/immobilized structures for different applications. For instance, detection- and sensing-based applications, environmental- and sustainability-based applications, and biocatalytic and biotransformation applications are of supreme interest. Considering the above points, herein we reviewed current advances in multifunctional hNFs, with particular emphasis on (1) critical factors, (2) different metal/non-metal-based synthesizing processes (i.e., (i) copper-based hNFs, (ii) calcium-based hNFs, (iii) manganese-based hNFs, (iv) zinc-based hNFs, (v) cobalt-based hNFs, (vi) iron-based hNFs, (vii) multi-metal-based hNFs, and (viii) non-metal-based hNFs), and (3) their applications. Moreover, the interfacial mechanism involved in hNF development is also discussed considering the following three critical points: (1) the combination of metal ions and organic matter, (2) petal formation, and (3) the generation of hNFs. In summary, the literature given herein could be used to engineer hNFs for multipurpose applications in the biosensing, biocatalysis, and other environmental sectors.

Comparison Study of Synthesized Red (or Blood) Orange Peels and Juice Extract-Nanoflowers and Their Antimicrobial Properties on Fish Pathogen (Yersinia ruckeri)

Abstract

In this work, we synthesized blood orange peel extract-copper (II) (Cu²⁺) ions nanoflower (NFs) and blood orange juice extract-copper (II) (Cu²⁺) ions nanoflower examine their antimicrobial properties on the fish pathogen (Yersinia ruckeri). The main compounds of the blood orange peel extract and the blood orange juice extract were organic components, and the copper (II) (Cu^{2 +}) ions were inorganic components. BOPE-Cu^{2 +} nanoflowers are quite compact, porous, and uniform as compared to BOJE-Cu²⁺ nanoflowers. Scanning Electron Microscopy, Fourier Transform Infrared spectrometry, and Energy-Dispersive X-ray spectroscopy were used to observe the structures of the NFs. The findings of FT-IR show Cu-O and Cu-N bonds in NF, which may be an indicator of the development of NFs. Although the antimicrobial actions of BOPE-hNFs and BOJE-hNFs against Yersinia ruckeri (NCTC 12,268) have been confirmed.

Graphic Abstract

Rhus vernicifera Laccase Immobilization on Magnetic Nanoparticles to Improve Stability and Its Potential Application in Bisphenol A Degradation

In the present study, Rhus vernicifera laccase (RvLac) was immobilized through covalent methods on the magnetic nanoparticles. Fe₂O₃ and Fe₃O₄ nanoparticles activated by 3-aminopropyltriethoxysilane followed with glutaraldehyde showed maximum immobilization yields and relative activity up to 81.4 and 84.3% at optimum incubation and pH of 18 h and 5.8, respectively. The maximum RvLac loading of 156 mg/g of support was recorded on Fe₂O₃ nanoparticles. A higher optimum pH and temperature of 4.0 and 45 °C were noted for immobilized enzyme compared to values of 3.5 and 40 °C for free form, respectively. Immobilized RvLac exhibited better relative activity profiles at various pH and temperature ranges. The immobilized enzyme showed up to 16-fold improvement in the thermal stability, when incubated at 60 °C, and retained up to 82.9% of residual activity after ten cycles of reuses. Immobilized RvLac exhibited up to 1.9-fold higher bisphenol A degradation efficiency potential over free enzyme. Previous reports have demonstrated the immobilization of RvLac on non-magnetic supports. This study has demonstrated that immobilization of RvLac on magnetic nanoparticles is very efficient especially for achieving high loading, better pH and temperature profiles, and thermal- and solvents-stability, high reusability, and higher degradation of bisphenol A.

Characterization of Cellobiohydrolases from Schizophyllum commune KMJ820

A novel cellobiohydrolase (CBH)-generating fungi have been isolated and categorized as Schizophyllum commune KMJ820 based on morphology and rDNA gene sequence. Cellulose powder was used as carbon source, the total enzyme activity was 11.51 U/ml is noted; which is among the highest amounts of CBH-generating microbes studied. CBH have been purified to homogenize, with pursual of serial chromatography using S. commune supernatants and two different CBHs were found; CBH 1 and 2. The filtered CBHs showed greater activity (V max = 51.4 and 20.8 U/mg) in contrast to CBHs from earlier studies. The MW (molecular weights) of S. commune CBH 1 and 2 were verified to be approximately 50 kDa and 150 kDa, respectively, by size exclusion chromatography. Even though CBHs have been evaluated from other sources, but S. commune CBH is prominent in comparison to other CBHs by its high enzyme activity.

One-step hydrothermal synthesis of magnetic rice straw for effective lipase immobilization and its application in esterification reaction

Immobilization of industrially important enzymes on supports is important to decrease the cost of the overall enzymatic production procedure. Herein, a novel method for synthesizing a new support, magnetic rice straw (MRS) in one step is reported: rice straw (RS) was soaked with Fe²⁺ ions and these were further reduced to form embedded Fe₂O₃ nanoparticles on the RS surface, forming MRS. This material presented a magnetic saturation value of 27.32 emu g^-1. Lipase immobilization on MRS resulted in 94.3% immobilization efficiency and 91.3 mg g^-1 of enzyme loading, which are higher than immobilization on native RS. The lipase stability was increased approximately 8-fold at 70 °C. The lipase-MRS composite was tested in the esterification reaction of biodiesel production, where it showed prominent reusability. Therefore, this novel and rapid synthesis method can provide ecological and economic support for enzyme immobilization and industrially important product formation.

Solvent-Tolerant Acyltransferase from Bacillus sp. APB-6: Purification and Characterization

Amidase from Bacillus sp. APB-6 with very good acyltransferase activity was purified to homogeneity with a purification fold of 3.68 and 53.20% enzyme yield. The purified protein's subunit molecular mass was determined approximately 42 kDa. Hyperactivity of the enzyme was observed at pH 7.5 (150 mM, potassium-phosphate buffer) and 50 °C of incubation. An enhancement in activity up to 42% was recorded with ethylenediaminetetraacetic acid and dithiothreitol. The kinetic parameter K _m values for substrates: acetamide and hydroxylamine-hydrochloride were 73.0 and 153 mM, respectively. Further, the V _max for acyltransferase activity was 1667 U/mg of protein and the K _i for acetamide was calculated as 37.0 mM. The enzyme showed tolerance to various organic solvents (10%, v/v) and worked well in the biphasic reaction medium. The acyltransferase activity in presence of solvents i.e. biphasic medium may prove highly favorable for the transformation of hydrophobic amides, which otherwise is not possible in simple aqueous phase.

Aligning Microbial Biodiversity for Valorization of Biowastes: Conception to Perception

Generation of biowastes is increasing rapidly and its uncontrolled, slow and persistent fermentation leads to the release of Green-house gases (GHGs) into the environment. Exploration and exploitation of microbial diversity for degrading biowastes can result in producing diverse range of bioactive molecules, which can act as a source of bioenergy, biopolymers, nutraceuticals and antimicrobials. The whole process is envisaged to manage biowastes, and reduce their pollution causing capacity, and lead to a sustainable society. A strategy has been proposed for: (1) producing bioactive molecules, and (2) achieving a zero-pollution emission by recycling of the GHGs through biological routes.

Flower Shaped Gold Nanoparticles: Biogenic Synthesis Strategies and Characterization

Microbes can serve as mediators for the fabrication of complicated nano-structures, obviating the tedious and time-consuming methods of synthesis. The shape of a nanoparticle has a very prominent role in defining the functionality in prospective arenas. So, the flower shaped nanoparticles are in focus nowadays due to their enhanced electrocatalytic and optical properties as compared to the spherical ones. We present the biosynthesis of flower shaped gold nanoparticles by Bacillus subtilis RSB64 and process parameters optimization using central composite design. The two well-separated scattering spectra showing absorption peaks at 540 nm and 750 nm indicate the presence of anisotropic gold nanoparticles and the results were corroborated by transmission electron microscopy analysis. The presence of gold nanoparticles was further confirmed by energy dispersive X-ray studies. The functional groups responsible for the stability of gold nanoparticles were predicted by Fourier transform infrared spectroscopy. The gold nanoparticles biosynthesis were collective effects of three experimental process parameters viz pH, temperature and precursor concentration. These three parameters were statistically optimized wherein pH 11.0, substrate concentration 1:1 (v/v) and temperature of 50 °C resulted in the synthesis of stable flower shaped gold nanoparticles of 50 nm size. The results indicated the tailored biosynthesis of gold nanoparticles with a flower like morphology by multi process parameter analysis to finalize robust conditions for the synthesis using B. subtilis RSB64. These gold nanoflowers demonstrate increased surface area efficiency/reactivity and could be employed for sustained and controlled delivery of drugs.

Engineering enzyme-coupled hybrid nanoflowers: The quest for optimum performance to meet biocatalytic challenges and opportunities

The current industrial revolution signifies the high-value of biocatalysis engineering. Over the past decade, multiple micro- and nanostructured materials have been attempted for immobilization of enzymes to improve their catalytic properties. Conventional immobilization strategies result in improved stability, while insolubilized enzymes generally lost their activity compared to free counterparts. Recently, a new generation organic-inorganic hybrid nanoflowers with unique properties have received great attention as a novel and incentive immobilization approach owing to their simple fabrication, high biocatalytic efficiency, and enzyme stabilizing capability. The hybrid nanoflowers biocatalytic system implicates metal ions and biomolecules (enzymes). In contrast to free or conventionally immobilized enzymes, single enzyme or multi enzyme-incorporated flowers-like hybrid nanoconstructs demonstrated elevated catalytic activities and stabilities over a very broader range of experimental conditions, i.e., pHs, temperatures and salt concentration. This review discusses the recent developments in the fabrication strategies to diversifying nanoflowers, types, characteristics, and applications of organic-inorganic hybrid nanoflowers as a host platform to engineer different kinds of enzymes with requisite functionalities for biocatalysis applications in different sectors of the modern world. Based on experimental and theoretical literature data, the review is wrapped up with concluding remarks and an outlook in terms of upcoming challenges and prospects for their scale-up applications.

Influence of Metal Ions on the Immobilization of β-Glucosidase Through Protein-Inorganic Hybrids

Immobilization of enzymes through metal-based system is demonstrated as a promising approach to enhance its properties. In this study, the influence of metals ions, including copper, cobalt and zinc (Zn) on the immobilization of β-glucosidase (BGL) through the synthesis of protein-inorganic hybrid was evaluated at 4 °C. Among these metal ions-based hybrids, Zn showed the highest encapsulation yield and relative activity of 87.5 and 207%, respectively. Immobilized BGL exhibited higher pH and temperature stability compared to free form. Thermal stability of hybrid improved up to 26-fold at 60 °C. After 10 cycles of reuse, immobilized enzyme retained 93.8% of residual activity. These results suggested that metal ions played a significant role in the enzyme immobilization as a protein-inorganic hybrid. Overall, this strategy can be potentially applied to enhance the properties of enzymes though effective encapsulation for the broad biotechnological applications.

Copper Ferrite Magnetic Nanoparticles for the Immobilization of Enzyme

In this study, novel, hollow superparamagnetic copper ferrite (CuFe₂O₄) nanoparticles (NPs) were synthesized by a low-temperature hydrothermal method. The hollow magnetic spheres were characterized by field emission scanning electron microscopy and high resolution transmission electron microscopy to confirm their morphology and size. The hollow NPs were demonstrated as the support for biological materials by the immobilization of Thermomyces lanuginosus lipase on the inner and outer surfaces of the hollow spheres. The immobilization of the enzyme was confirmed by Fourier Transform Infra-red spectroscopy and confocal laser scanning microscopy. The immobilized enzyme was shown to have an immobilization efficiency of 84.5%, with approximately 176 mg g^-1 of enzyme loading, for the hollow-NPs support. The immobilized enzyme exhibited high storage and temperature stability. The reusability of the immobilized lipase was more than 80% after 10 cycles of repeated use.