Enzyme immobilization with nanomaterials for hydrolysis of lignocellulosic biomass: Challenges and future Perspectives

Enzyme immobilization has emerged as a prodigious strategy in the enzymatic hydrolysis of lignocellulosic biomass (LCB) promising enhanced efficacy and stability of the enzymes. Further, enzyme immobilization on magnetic nanoparticles (MNPs) facilitates the easy recovery and reuse of biocatalysts. This results in the development of a nanobiocatalytic system, that serves as an eco-friendly and inexpensive LCB deconstruction approach. This review provides an overview of nanomaterials used for immobilization with special emphasis on the nanomaterial-enzyme interactions and strategies of immobilization. After the succinct outline of the immobilization procedures and supporting materials, a comprehensive assessment of the catalysis enabled by nanomaterial-immobilized biocatalysts for the conversion and degradation of lignocellulosic biomasses is provided by gathering state-of-the-art examples. The challenges and future directions associated with this technique providing a potential solution in the present article. Insight on the recent advancements in the process of nanomaterial-based immobilization for the hydrolysis of lignocellulosic biomass has also been highlighted in the article.

The Expansion of Lignocellulose Biomass Conversion Into Bioenergy via Nanobiotechnology

Lignocellulosic biomass has arisen as a solution to our energy and environmental challenges because it is rich in feedstock that can be converted to biofuels. Converting lignocellulosic biomass to sugar is a complicated system involved in the bioconversion process. There are indeed a variety of techniques that have been utilized in the bioconversion process consisting of physical, chemical, and biological approaches. However, most of them have drawbacks when used on a large scale, which include the high cost of processing, the development of harmful inhibitors, and the detoxification of the inhibitors that have been produced. These constraints, taken together, hinder the effectiveness of current solutions and demand for the invention of a new, productive, cost-effective, and environmentally sustainable technique for LB processing. In this context, the approach of nanotechnology utilizing various nanomaterials and nanoparticles in treating lignocellulose biomass and bioenergy conversion has achieved increased interest and has been explored greatly in recent times. This mini review delves into the application of nanotechnological techniques in the bioconversion of lignocellulose biomass into bioenergy. This review on nanotechnological application in biomass conversion provides insights and development tools for the expansion of new sectors, resulting in excellent value and productivity, contributing to the long-term economic progress.

Recent nanobiotechnological advancements in lignocellulosic biomass valorization: A review

Increase in human population, rapid industrialization, excessive utilization of fossil fuel utilization and anthropogenic activities have caused serious threats to the environment in terms of greenhouse gas emissions (GHGs), global warming, air pollution, acid rain, etc. This destruction in sustainability can be averted by a paradigm shift in the fuel production from fossil resources to bioenergy. Amongst different forms of bioenergy, lignocellulosic biomass can be utilized as an attractive substrate for the production of several high-value products owing to its renewability, easy availability, and abundance. Additionally, utilization of these waste biomasses reduces the environmental hazards associated with its disposal. Impedance of lignin and crystalline nature of cellulose pose major bottlenecks in biomass based energy. Though, several physio-chemicals processes are recommended as mitigation route but none of them seems to be promising for large scale application. In recent years, a right fusion of biological treatment combined with nanotechnology for efficient pretreatment and subsequent hydrolysis of biomass by ubiquitous enzymes seems to be promising alternative. In addition, to overcome these difficulties, nanotechnology-based methods have been recently adopted in catalytic valorization of lignocellulosic biomass. The present review has critically discussed the application of nano-biotechnology in lignocellulosic biomass valorization in terms of pretreatment and hydrolysis. A detailed discussion on the application of various nanoparticles in these processes, enzyme immobilization and end-production utilization is presented in this review. Finally, the review emphasizes the major challenges of this process along with different routes and recommendations to address the issues.

Optimization of biogas yield from lignocellulosic materials with different pretreatment methods: a review

Population increase and industrialization has resulted in high energy demand and consumptions, and presently, fossil fuels are the major source of staple energy, supplying 80% of the entire consumption. This has contributed immensely to the greenhouse gas emission and leading to global warming, and as a result of this, there is a tremendous urgency to investigate and improve fresh and renewable energy sources worldwide. One of such renewable energy sources is biogas that is generated by anaerobic fermentation that uses different wastes such as agricultural residues, animal manure, and other organic wastes. During anaerobic digestion, hydrolysis of substrates is regarded as the most crucial stage in the process of biogas generation. However, this process is not always efficient because of the domineering stableness of substrates to enzymatic or bacteria assaults, but substrates' pretreatment before biogas production will enhance biogas production. The principal objective of pretreatments is to ease the accessibility of the enzymes to the lignin, cellulose, and hemicellulose which leads to degradation of the substrates. Hence, the use of pretreatment for catalysis of lignocellulose substrates is beneficial for the production of cost-efficient and eco-friendly process. In this review, we discussed different pretreatment technologies of hydrolysis and their restrictions. The review has shown that different pretreatments have varying effects on lignin, cellulose, and hemicellulose degradation and biogas yield of different substrate and the choice of pretreatment technique will devolve on the intending final products of the process.

How does DNA 'meet' capillary-based microsystems?

DNA possesses various chemical and physical properties which make it important in biological analysis. The opportunity for DNA to 'meet' capillary-based microsystems is rapidly increasing owing to the expanding development of miniaturization. Novel capillary-based methods can provide favourable platforms for DNA-ligand interaction assay, DNA translocation study, DNA separation, DNA aptamer selection, DNA amplification assay, and DNA digestion. Meanwhile, DNA exhibits great potential in the fabrication of new capillary-based biosensors and enzymatic bioreactors. Moreover, DNA has received significant research interest in improving capillary electrophoresis (CE) performance. We focus on highlighting the advantages of combining DNA and capillary-based microsystems. The general trend presented in this review suggests that the 'meeting' has offered a stepping stone for the application of DNA and capillary-based microsystems in the field of analytical chemistry.

Current Developments in Lignocellulosic Biomass Conversion into Biofuels Using Nanobiotechology Approach

The conversion of lignocellulosic biomass (LB) to sugar is an intricate process which is the costliest part of the biomass conversion process. Even though acid/enzyme catalysts are usually being used for LB hydrolysis, enzyme immobilization has been recognized as a potential strategy nowadays. The use of nanobiocatalysts increases hydrolytic efficiency and enzyme stability. Furthermore, biocatalyst/enzyme immobilization on magnetic nanoparticles enables easy recovery and reuse of enzymes. Hence, the exploitation of nanobiocatalysts for LB to biofuel conversion will aid in developing a lucrative and sustainable approach. With this perspective, the effects of nanobiocatalysts on LB to biofuel production were reviewed here. Several traits, such as switching the chemical processes using nanomaterials, enzyme immobilization on nanoparticles for higher reaction rates, recycling ability and toxicity effects on microbial cells, were highlighted in this review. Current developments and viability of nanobiocatalysts as a promising option for enhanced LB conversion into the biofuel process were also emphasized. Mostly, this would help in emerging eco-friendly, proficient, and cost-effective biofuel technology.

Glucose Oxidase Immobilized on Magnetic Zirconia: Controlling Catalytic Performance and Stability

Here, we report the structures and properties of biocatalysts based on glucose oxidase (GOx) macromolecules immobilized on the mesoporous zirconia surface with or without magnetic iron oxide nanoparticles (IONPs) in zirconia pores. Properties of these biocatalysts were studied in oxidation of d-glucose to d-gluconic acid at a wide range of pH and temperatures. We demonstrate that the calcination temperature (300, 400, or 600 °C) of zirconia determines its structure, with crystalline materials obtained at 400 and 600 °C. This, in turn, influences the catalytic behavior of immobilized GOx, which was tentatively assigned to the preservation of GOx conformation on the crystalline support surface. IONPs significantly enhance the biocatalyst activity due to synergy with the enzyme. At the same time, neither support porosity nor acidity/basicity shows correlations with the properties of this biocatalyst. The highest relative activity of 98% (of native GOx) at a pH 6-7 and temperature of 40-45 °C was achieved for the biocatalyst based on ZrO₂ calcined at 600 °C and containing IONPs. This process is green as it is characterized by a high atom economy due to the formation of a single product with high selectivity and conversion and minimization of waste due to magnetic separation of the catalyst from an aqueous solution. These and an exceptional stability of this catalyst in 10 consecutive reactions (7% relative activity loss) make it favorable for practical applications.

Novel approaches for biomolecule immobilization in microscale systems

This manuscript reviews novel approaches applied for biomolecule immobilization in microscale systems.

Magnetic-propelled Fe3O4–chitosan carriers enhancel-asparaginase catalytic activity: a promising strategy for enzyme immobilization

Magnetic-propelled carriers comprising magnetic Fe₃O₄–chitosan nanoparticles were immobilized with l-asparaginase (l-ASNase). The enzyme displayed enhanced catalytic activity in a weak magnetic field, and thermal and pH stabilities. The conjugated l-ASNase presented higher thermostability and wider range of pH stability in comparison with those of free l-ASNase. Moreover, the reusability of conjugated l-ASNase significantly improved after immobilization and it retained 60.5% of its initial activity after undergoing 16 cycles. The conjugated l-ASNase maintained more than 50% and 48% initial activity after 4 weeks of storage at 4 °C and room temperature, respectively. Furthermore, we reveal that the activity of conjugated l-ASNase onto magnetic Fe₃O₄–chitosan particles increased by about 3-fold in the weak magnetic field at certain frequencies and flux density compared with that of free l-ASNase. Considering these excellent attributes, the magnetic-propelled mechanism in the transporting and activation of l-ASNase can be used by enhancing the catalytic activity, stability, and efficiency in vital implications for medicinal biotechnology.

A magnetic-propelled carrier comprising chitosan-coated Fe₃O₄ nanoparticles was prepared to enhance the catalytic activity of immobilized l-asparaginase in a weak magnetic field.