Agarose-chitosan hydrogel-immobilized horseradish peroxidase with sustainable bio-catalytic and dye degradation properties

Purification and immobilization of β-glucosidase using surface modified mesoporous silica Santa Barbara Amorphous 15 for eco-friendly preparation of sagittatoside A

Functionalized mesoporous materials have become a promising carrier for enzyme immobilization. In this study, Santa Barbara Amorphous 15 (SBA-15) was modified by N-aminoethyl-γ-aminopropyl trimethoxy (R). R-SBA-15 was employed to purify and immobilize recombinant β-glucosidase from Terrabacter ginsenosidimutans (BgpA) in one step for the first time. Optimum pH of the constructed R-SBA-15@BgpA were 7.0, and it has 20 ℃ higher optimal temperature than free enzyme. Relative activity of R-SBA-15@BgpA still retained > 70% at 42 ℃ after 8-h incubation. The investigation on organic reagent resistance revealed that the immobilized enzyme can maintain strong stability in 15% DMSO. In leaching test and evaluation of storage stability, only trace amount of protein was detected in buffer of the immobilized enzyme after storage at 4 ℃ for 33 days, and the immobilized BgpA still maintained > 50% relative activity. It also demonstrated good reusability, with 76.1% relative activity remaining after fourteen successive enzymatic hydrolyses of epimedin A to sagittatoside A. The newly proposed strategy is an effective approach for the purification and immobilization of BgpA concurrently. In addition, R-SBA-15@BgpA was demonstrated to have high efficiency and stability in this application, suggesting its great feasibility and potential to produce bioactive compounds such as secondary glycosides or aglycones from natural products.

Construction of immobilized laccase hydrogels via sodium alginate-dopamine/polyethylene glycol and its efficient degradation of dyeing wastewater

Laccases with highly catalytic properties have been widely used in developing green applications for water remediation. However, the poor stability and low reutilization rate of free laccase make it difficult to be applied practically. Hence, in this study, an immobilized laccase was prepared using dopamine (DA) functionalized sodium alginate (SA)/polyethylene glycol (PEG) composite hydrogels to realize the recyclability of the laccase. The SA/PEG composite hydrogels, as the protective carrier for laccase, exhibited excellent catalytic stability in various interfering environments. After 30 days, Lac@SA-PDA/PEG beads could remain 70.23 % of the initial activity, as the residual activity of free laccase was only 12.35 %. When free laccase and Lac@SA-PDA/PEG beads were used for decolorization of Reactive Blue 19 (RB-19,100 mg/L), the degradation rate of Lac@SA-PDA/PEG is 6.88 times higher than free laccase. More importantly, the SA-PDA/PEG composite hydrogel exhibited a high reutilization rate, which after six cycles, Lac@SA-PDA/PEG beads retained 90.23 % of its initial activity. Besides, the degradation effect of Lac@SA-PDA/PEG on different dyes was analyzed. In addition, the conjectured degradation pathways of RB-19 by laccase were analyzed. The work showed that immobilized laccase has tremendous potential for the treatment of dyestuff wastewater.

Encapsulation of HRP-Immobilized Silica Particles into Hollow-Type Spherical Bacterial Cellulose Gel: A Novel Approach for Enzyme Reactions within Cellulose Gel Capsules

We revealed that the encapsulation of enzyme-immobilized silica particles in hollow-type spherical bacterial cellulose (HSBC) gels enables the use of the inside of HSBC gels as a reaction field. The encapsulation of horseradish peroxidase (HRP)-immobilized silica particles (Si-HRPs, particle size: 40-50 μm) within HSBC gels was performed by using a BC gelatinous membrane produced at the interface between Komagataeibacter xylinus suspension attached onto an alginate gel containing Si-HRPs and silicone oil. After the biosynthesis of the BC gelatinous membrane, formed from cellulose nanofiber networks, the alginate gel was removed via immersion in a phosphate-buffered solution. Si-HRP encapsulated HSBC gels were reproducibly produced using our method with a yield of over 90%. The pore size of the network structure of the BC gelatinous membrane was less than 1 μm, which is significantly smaller than the encapsulated Si-HRPs. Consequently, the encapsulated Si-HRPs could neither pass through the BC gelatinous membrane nor leak from the interior cavity of the HSBC gel. The activity of the encapsulated HRPs was detected using the 3,3',5,5'-tetramethylbenzidine (TMB)-H2O2 system, demonstrating that this method can encapsulate the enzyme without inactivation. Since HSBC gels are composed of a network structure of biocompatible cellulose nanofibers, immune cells cannot enter the hollow interior, thus, the enzyme-immobilized particles encapsulated inside the HSBC gel are protected from immune-cell attacks. The encapsulation technique demonstrated in this study is expected to facilitate the delivery of enzymes and catalysts that are not originally present in the in vivo environment.

Utilizing immobilized recombinant serine alkaline protease from Bacillus safensis lab418 in wound healing: Gene cloning, heterologous expression, optimization, and characterization

Microbial proteases have proven their efficiency in various industrial applications; however, their application in accelerating the wound healing process has been inconsistent in previous studies. In this study, heterologous expression was used to obtain an over-yielding of the serine alkaline protease. The serine protease-encoding gene aprE was isolated from Bacillus safensis lab 418 and expressed in E. coli BL21 (DE3) using the pET28a (+) expression vector. The gene sequence was assigned the accession number OP610065 in the NCBI GenBank. The open reading frame of the recombinant protease (aprEsaf) was 383 amino acids, with a molecular weight of 35 kDa. The yield of aprEsaf increased to 300 U/mL compared with the native serine protease (SAFWD), with a maximum yield of 77.43 U/mL after optimization conditions. aprEsaf was immobilized on modified amine-functionalized films (MAFs). By comparing the biochemical characteristics of immobilized and free recombinant enzymes, the former exhibited distinctive biochemical characteristics: improved thermostability, alkaline stability over a wider pH range, and efficient reusability. The immobilized serine protease was effectively utilized to expedite wound healing. In conclusion, our study demonstrates the suitability of the immobilized recombinant serine protease for wound healing, suggesting that it is a viable alternative therapeutic agent for wound management.

Membrane-Free Lateral Flow Assay with the Active Control of Fluid Transport for Ultrasensitive Cardiac Biomarker Detection

Membrane-based lateral flow immunoassays (LFAs) have been employed as early point-of-care (POC) testing tools in clinical settings. However, the varying membrane properties, uncontrollable sample transport in LFAs, visual readout, and required large sample volumes have been major limiting factors in realizing needed sensitivity and desirable precise quantification. Addressing these challenges, we designed a membrane-free system in which the desirable three-dimensional (3D) structure of the detection zone is imitated and used a small pump for fluid flow and fluorescence as readout, all the while maintaining a one-step assay protocol. A hydrogel-like protein-polyelectrolyte complex (PPC) within a polyelectrolyte multilayer (PEM) was developed as the test line by complexing polystreptavidin (pSA) with poly(diallyldimethylammonium chloride) (PDDA), which in turn was layered with poly(acrylic acid) (PAA) resulting in a superior 3D streptavidin-rich test line. Since the remainder of the microchannel remains material-free, good flow control is achieved, and with the total volume of 20 μL, 7.5-fold smaller sample volumes can be used in comparison to conventional LFAs. High sensitivity with desirable reproducibility and a 20 min total assay time were achieved for the detection of NT-proBNP in plasma with a dynamic range of 60-9000 pg·mL-1 and a limit of detection of 56 pg·mL-1 using probe antibody-modified fluorescence nanoparticles. While instrument-free visual detection is no longer possible, the developed lateral flow channel platform has the potential to dramatically expand the LFA applicability, as it overcomes the limitations of membrane-based immunoassays, ultimately improving the accuracy and reducing the sample volume so that finger-prick analyses can easily be done in a one-step assay for analytes present at very low concentrations.

pH-dependent and whole-cell catalytic decolorization of dyes using recombinant dye-decolorizing peroxidase from Rhodococcus jostii

Dyes in wastewater have adverse effects on the environment and human health. Dye-decolorizing peroxidase (DyP) is a promising biocatalyst to dyes degradation, but the decolorization rates varied greatly which influencing factors and mechanisms remain to be fully disclosed. To explore an effective decolorizing approach, we have studied a DyP from Rhodococcus jostii (RhDyPB) which was overexpressed in Escherichia coli to decolorize four kinds of dyes, Reactive blue 19, Eosin Y, Indigo carmine, and Malachite green. We found the decolorization rates of the dyes by purified RhDyPB were all pH-dependent and the highest one was 94.4% of Malachite green at pH 6.0. ESI-MS analysis of intermediates in the decolorization process of Reactive blue 19 proved the degradation was due to peroxidase catalysis. Molecular docking predicated the interaction of RhDyPB with dyes, and a radical transfer reaction. In addition, we performed decolorization of dyes with whole E. coli cell with and without expressing RhDyPB. It was found that decolorization of dyes by E. coli cell was due to both cell absorption and degradation, and RhDyPB expression improved the degradation rates towards Reactive blue 19, Indigo carmine and Malachite green. The effective decolorization of Malachite green and the successful application of whole DyP-overexpressed cells in dye decolorization is conducive to the bioremediation of dye-containing wastewaters by DyPs.

Recent advances in degradation of N,N-diethyl-3-toluamide (DEET)-an emerging environmental contaminant: a review

N,N-Diethyl-3-toluamide (DEET) is a commonly used insect repellent, which acts as an organic chemical contaminant in water and considered as an emerging contaminant which has been observed worldwide. It gets discharged into the environment through sewage waste. The various methods have been used to degrade DEET, such as UV based, ozonation, photocatalytic degradation, and biodegradation (based on the metabolic activity of fungi and bacteria). However, less research has been done on the degradation of DEET by deploying nanoparticles. Therefore, biodegradation and nanotechnology-based methods can be the potential solution to remediate DEET from the environment. This review is an attempt to analyze the routes of entry of DEET into the atmosphere and its environmental health consequences and to explore physical, chemical, and biological methods of degradation. Furthermore, it focuses on the various methods used for the biodegradation of the DEET, including their environmental consequences. Future research is needed with the application of biological methods for the degradation of DEET. Metabolic pathway for biodegradation was explored for the new potent microbial strains by the application of physical, chemical, and microbial genomics; molecular biology; genetic engineering; and genome sequencing methods.

Pros and Cons in Various Immobilization Techniques and Carriers for Enzymes

In recent years, enzyme immobilization technology has been developed, and studies on immobilized enzyme materials have become very prominent. With the immobilization technique, enzymes and compatible carrier materials are combined or enzyme crystals/aggregates are used in a carrier-free fashion, by physical, chemical, or biochemical methods. As a kind of biocatalyst, immobilized enzymes can catalyze certain chemical reactions with high selectivity and high efficiency under relatively mild reaction conditions and eliminate pollution to the environment. Considering the current status and applications of immobilized enzyme technology and materials emerging in the last 5 years, this mini-review introduces the advantages and disadvantages of various enzyme immobilization techniques with carriers as well as the pros and cons of different materials for immobilization. The future prospects of immobilization technology and carrier materials are outlined, aiming to provide a reference for further research and applications of sustainable technology.

Recent advances in cellulose- and alginate-based hydrogels for water and wastewater treatment: A review

From the environmental perspective, it is essential to develop cheap, eco-friendly, and highly efficient materials for water and wastewater treatment. In this regard, hydrogels and hydrogel-based composites have been widely employed to mitigate global water pollution as this methodology is simple and free from harmful by-products. Notably, alginate and cellulose, which are natural carbohydrate polymers, have gained great attention for their availability, price competitiveness, excellent biodegradability, biocompatibility, hydrophilicity, and superior physicochemical performance in water treatment. This review outlined the recent progress in developing and applying alginate- and cellulose-based hydrogels to remove various pollutants such as dyes, heavy metals, oils, pharmaceutical contaminants, and pesticides from wastewater streams. This review also highlighted the effects of various physical or chemical methods, such as crosslinking, grafting, the addition of fillers, nanoparticle incorporation, and polymer blending, on the physiochemical and adsorption properties of hydrogels. In addition, this review covered the alginate- and cellulose-based hydrogels' current limitations such as low mechanical performance and poor stability, while presenting strategies to improve the drawbacks of the hydrogels. Lastly, we discussed the prospects and future directions of alginate- and cellulose-based hydrogels. We hope this review provides valuable insights into the efficient preparations and applications of hydrogels.

Bio-mitigation of organic pollutants using horseradish peroxidase as a promising biocatalytic platform for environmental sustainability

A wide array of environmental pollutants is often generated and released into the ecosystem from industrial and human activities. Antibiotics, phenolic compounds, hydroquinone, industrial dyes, and Endocrine-Disrupting Chemicals (EDCs) are prevalent pollutants in water matrices. To promote environmental sustainability and minimize the impact of these pollutants, it is essential to eliminate such contaminants. Although there are multiple methods for pollutants removal, many of them are inefficient and environmentally unfriendly. Horseradish peroxidase (HRP) has been widely explored for its ability to oxidize the aforementioned pollutants, both alone and in combination with other peroxidases, and in an immobilized way. Numerous positive attributes make HRP an excellent biocatalyst in the biodegradation of diverse environmentally hazardous pollutants. In the present review, we underlined the major advancements in the HRP for environmental research. Numerous immobilization and combinational studies have been reviewed and summarized to comprehend the degradability, fate, and biotransformation of pollutants. In addition, a possible deployment of emerging computational methodologies for improved catalysis has been highlighted, along with future outlook and concluding remarks.

Immobilization of Horseradish Peroxidase on Ca Alginate-Starch Hybrid Support: Biocatalytic Properties and Application in Biodegradation of Phenol Red Dye

In this study, horseradish peroxidase was extracted, purified, and immobilized on a calcium alginate-starch hybrid support by covalent bonding and entrapment. The immobilized HRP was used for the biodegradation of phenol red dye. A 3.74-fold purification was observed after precipitation with ammonium sulfate and dialysis. An immobilization yield of 88.33%, efficiency of 56.89%, and activity recovery of 50.26% were found. The optimum pH and temperature values for immobilized and free HRP were 5.0 and 50 °C and 6.5 and 60 °C, respectively. The immobilized HRP showed better thermal stability than its free form, resulting in a considerable increase in half-life time (t1/2) and deactivation energy (Ed). The immobilized HRP maintained 93.71% of its initial activity after 45 days of storage at 4 °C. Regarding the biodegradation of phenol red, immobilized HRP resulted in 63.57% degradation after 90 min. After 10 cycles of reuse, the immobilized HRP was able to maintain 43.06% of its initial biodegradative capacity and 42.36% of its enzymatic activity. At the end of 15 application cycles, a biodegradation rate of 8.34% was observed. In conclusion, the results demonstrate that the immobilized HRP is a promising option for use as an industrial biocatalyst in various biotechnological applications.

A critical review of enzymes immobilized on chitosan composites: characterization and applications

Enzymes with industrial significance are typically used in biological processes. However, instability, high sensitivity, and impractical recovery are the major drawbacks of enzymes in practical applications. In recent years, the immobilization technology has attracted wide attention to overcoming these restrictions and improving the efficiency of enzyme applications. Chitosan (CS) is a unique functional substance with biocompatibility, biodegradability, non-toxicity, and antibacterial properties. Chitosan composites are anticipated to be widely used in the near future for a variety of purposes, including as supports for enzyme immobilization, because of their advantages. Therefor this review explores the effects of the chitosan's structure, molecular weight, degree of deacetylation on the enzyme immobilized, effect of key factors, and the enzymes immobilized on chitosan based composites for numerous applications, including the fields of biosensor, biomedical science, food industry, environmental protection, and industrial production. Moreover, this study carefully investigates the advantages and disadvantages of using these composites as well as their potential in the future.

Immobilization of commercial horseradish peroxidase in calcium alginate-starch hybrid support and its application in the biodegradation of phenol red dye

In this study, horseradish peroxidase (HRP) was immobilized for the first time on Ca alginate-starch hybrid beads and employed for the biodegradation of phenol red dye. The optimal protein loading was 50 mg/g of support. Immobilized HRP demonstrated improved thermal stability and maximum catalytic activity at 50 °C and pH 6.0, with an increase in half-life (t1/2) and enzymatic deactivation energy (Ed) compared to free HRP. After 30 days of storage at 4 °C, immobilized HRP retained 109% of its initial activity. Compared to free HRP, the immobilized enzyme exhibited higher potential for phenol red dye degradation, as evidenced by the removal of 55.87% of initial phenol red after 90 min, which was 11.5 times greater than free HRP. In sequential batch reactions, the immobilized HRP demonstrated good potential efficiency for the biodegradation of phenol red dye. The immobilized HRP was used for a total of 15 cycles, degrading 18.99% after 10 cycles and 11.69% after 15 cycles, with a residual enzymatic activity of 19.40% and 12.34%, respectively. Overall, the results suggest that HRP immobilized on Ca alginate-starch hybrid supports shows promise as a biocatalyst for industrial and biotechnological applications, particularly for the biodegradation of recalcitrant compounds such as phenol red dye.

Immobilization of horseradish peroxidase with zwitterionic polymer material for industrial phenolic removal

Horseradish peroxidase (HRP) is a hemoglobin composed of a single peptide chain that catalyzes the oxidation of various substrates such as phenol and aniline in the presence of hydrogen peroxide via its iron-porphyrin catalytic center. This enzyme is widely used in industrial phenol removal, food additives, biomedicine, and clinical test reagents due to its rapid reaction rate and obvious reaction outcomes. However, the large-scale use of HRP in industrial applications still faces numerous challenges, including activity, stability, and sustainability. This study demonstrates that when peroxidase is immobilized in zwitterionic polymer hydrogels, polycarboxybetaine (PCB) and polysulfobetaine (PSB), the properties of the enzyme are improved. PCB and PSB-embedded HRP exhibit a 6.11 and 1.53 times increase in Kcat/Km value, respectively, compared to the free enzyme. The immobilized enzyme also experiences increased activity over a range of temperatures and better tolerance to extreme pH and organic solvents, including formaldehyde. In addition, immobilized HRP exhibits excellent performance in storage and reproducibility. Remarkably, PCB-HRP still retains 80% of the initial activity after a 6-week storage period and can still attain the initial catalytic level of the free enzyme after six repeated cycles. It also removes 90% of phenol within 12 min, surpassing the current pharmacy on the market. These experimental results indicated that we have successfully designed a set of stable and efficient support substrates for horseradish peroxidase, which enhances its suitability for deployment in industrial applications.

Biodegradable Nanogels for Dermal Applications: An Insight

Abstract:

Biodegradable nanogels in the biomedical field are emerging vehicles comprising dispersions of hydrogel nanoparticles having 3D crosslinked polymeric networks. Nanogels show distinguished characteristics including their homogeneity, adjustable size, low toxicity, stability in serum, stimuli-responsiveness (pH, temperature, enzymes, light, etc.), and relatively good drug encapsulation capability. Due to these characteristics, nanogels are referred to as nextgeneration drug delivery systems and are suggested as promising carriers for dermal applications. The site-specific delivery of drugs with effective therapeutic effects is crucial in transdermal drug delivery. The nanogels made from biodegradable polymers can show external stimuliresponsiveness which results in a change in gel volume, water content, colloidal stability, mechanical strength, and other physical and chemical properties, thus improving the site-specific topical drug delivery. This review provides insight into the advances in development, limitations, and therapeutic significance of nanogels formulations. It also highlights the process of release of drugs in response to external stimuli, various biodegradable polymers in the formulation of the nanogels, and dermal applications of nanogels and their role in imaging, anti‐inflammatory therapy, antifungal and antimicrobial therapy, anti‐psoriatic therapy, and ocular and protein/peptide drug delivery.

Effect of Chitosan as Active Bio-colloidal Constituent on the Diffusion of Dyes in Agarose Hydrogel

Agarose hydrogel was enriched by chitosan as an active substance for the interactions with dyes. Direct blue 1, Sirius red F3B, and Reactive blue 49 were chosen as representative dyes for the study of the effect of their interaction with chitosan on their diffusion in hydrogel. Effective diffusion coefficients were determined and compared with the value obtained for pure agarose hydrogel. Simultaneously, sorption experiments were realized. The sorption ability of enriched hydrogel was several times higher in comparison with pure agarose hydrogel. Determined diffusion coefficients decreased with the addition of chitosan. Their values included the effects of hydrogel pore structure and interactions between chitosan and dyes. Diffusion experiments were realized at pH 3, 7, and 11. The effect of pH on the diffusivity of dyes in pure agarose hydrogel was negligible. Effective diffusion coefficients obtained for hydrogels enriched by chitosan increased gradually with increasing pH value. Electrostatic interactions between amino group of chitosan and sulfonic group of dyes resulted in the formation of zones with a sharp boundary between coloured and transparent hydrogel (mainly at lower pH values). A concentration jump was observed at a given distance from the interface between hydrogel and the donor dye solution.

Interfacial biosilica coating of chitosan gel using fusion silicatein to fabricate robust hybrid material for biomolecular applications

An enzyme-encapsulated silica-based hybrid material was developed using a chitosan gel. Fusion silicatein (InaKC-ChBD-Sil), silicatein fused with a soluble tag and chitin-binding domain, was employed as an interfacial catalyst to form silica on a chitosan gel matrix under physiological conditions, and horseradish peroxidase was immobilised on the hybrid material. Silica formation on the gel was verified via fluorescence microscopy using a designed fusion protein called TBP-mCherry, a fluorescent protein fused with a silica-binding peptide. We report a chitosan gel-silica hybrid material capable of encapsulating enzymes for biomedical and environmental applications.

Experimental investigation for treating ibuprofen and triclosan by biosurfactant from domestic wastewater

The presence of emerging pollutants of pharmaceutical products and personal care products (PPCPs) in the aquatic environment overspreads the threat on living beings. Bioremediation is a promising option for treating wastewater. In the present study, an experimental investigation was carried out to produce a biosurfactant by Pseudomonas aeruginosa (MTCC 1688) for the removal of Ibuprofen (IBU) and Triclosan (TCS) from domestic wastewater. It was performed in three stages. Firstly, the production and optimization of biosurfactant was carried out to arrive at the best combination of crude sunflower oil, sucrose and ammonium bicarbonate (10%: 5.5 g/L: 1 g/L) to yield effective biosurfactant production (crude biosurfactant) and further extended to achieve critical micelle concentration (CMC) formation by dilution (biosurfactant at 10.5%). The stability of the biosurfactant was also confirmed. Biosurfactant showed a reduction in the surface tension to 41 mN/m with a yield concentration of 11.2 g/L. Secondly, its effectiveness was evaluated for the removal of IBU and TCS from the domestic wastewater collected during the dry and rainy seasons. Complete removal of IBU was achieved at 36 h & 6 h and TCS at 6 h & 1 h by crude biosurfactant and biosurfactant at CMC formation for the dry season sample. IBU removal was achieved in 2 h by both crude and biosurfactant at CMC and no TCS was detected in the rainy season sample. Thirdly, biotransformation intermediates of IBU and TCS formed during the application of the biosurfactant and degradation pathways are proposed based on the Liquid Chromatography-Mass Spectrometry (LC-MS) and it indicates that there is no formation of toxic by-products. Based on the results, it is evident that biosurfactant at CMC has performed better for the removal of IBU and TCS than crude biosurfactants without any formation of toxic intermediates. Hence, this study proved to be an eco-friendly, cost-effective and sustainable treatment option for domestic wastewater treatment.

Facile synthesis of dual-hydrolase encapsulated magnetic ZIF-8 composite for efficient removal of multi-pesticides induced pollution in water

Multi-pesticides pollution induced by organophosphorus insecticides (OPs) and aryloxyphenoxypropionate herbicides (AOPPs) has become a significant challenge in bioremediation of water pollution due to their prolonged and over application. Though a number of physical, chemical, and biological approaches have been developed for different pesticides, the explorations usually focus on eliminating single pesticide pollution. Herein, a heterostructure nanocomposite OPH/QpeH@mZIF-8, encapsulating OPs hydrolase OPH and AOPPs hydrolase QpeH in the magnetic zeolitic imidazolate frameworks-8 (mZIF-8), was synthesized through a facile one-pot method in aqueous solution. The immobilized OPH and QpeH in mZIF-8 showed high activities towards the two most common OPs and AOPPs, i.e., chlorpyrifos and quizalofop-P-ethyl, which were hydrolyzed to 3,5,6-Trichloro-2-pyridino (TCP) and quizalofop acid, respectively. Moreover, the magnetic nanocatalyst possessed great tolerance towards broad pH range, high temperatures, and different chemical solvents and excellent recyclability. More importantly, compared to free OPH and QpeH, OPH/QpeH@mZIF-8, with significantly enhanced degradation capability, exhibited enormous potential for simultaneous removal of chlorpyrifos and quizalofop-p-ethyl from the surface and industrial wastewater. Overall, the study demonstrates the applicability of this strategy for utilizing magnetic nanocatalysts encapsulating multiple enzymes due to its simplicity, high efficiency, and economic benefits to removing pesticide compound pollution from various water resources.

Promotion of the genipin crosslinked chitosan-fiber hydrogel loaded with sustained release of clemastine fumarate in diabetic wound repair

Diabetic skin disorders are lingering and refractory clinical diseases. In this study, a genipin-crosslinked porous chitosan fiber (CSF) hydrogel was fabricated to achieve rapid wound healing. By embedding clemastine fumarate (CF) in the CSF hydrogel pores, we synthesised a CSF/CF hydrogel for the treatment of diabetic wounds. The microstructure, chemical elements, spectral variation, mechanical properties, swelling ratios, degradability, and toxicity of the CSF/CF hydrogels were studied. Compared with the typical CS power hydrogel, the porous CSF hydrogel crosslinked with genipin possesses a stable structure and improved physicochemical properties. Moreover, CF was slowly released from the CSF hydrogel. Molecular simulation also showed that CF was evenly embedded inside the cavity formed by the novel CSF hydrogel. The results suggested that CF can resist damage from high glucose levels and promote proliferation, tube formation, and migration of endothelial cells (ECs) and fibroblasts. The CSF/CF hydrogel promoted wound healing in a rat model. Mechanistically, the beneficial effect of CF on wound healing may be related to activation of the MEK/ERK and PI3K/Akt signalling pathways. In conclusion, genipin-crosslinked CSF/CF hydrogel can accelerate wound healing and may be an effective therapeutic method for treating diabetic skin lesions.

Recent advances in g-C3N4-based photo-enzyme catalysts for degrading organic pollutants

In recent years, photocatalytic reactions have shown great potential in degrading organic pollutants because of their simple operation and no secondary pollution. Graphitic carbon nitride (g-C₃N₄) is one of the most frequently used photocatalyst materials in the field of photocatalysis because it is a form of photocatalytic material with facile synthesis, no metal, visible light response, and strong stability. Enzyme-catalyzed degradation has received extensive attention due to its broad selectivity, high efficiency, and environmental friendliness. Horseradish peroxidase (HRP), one of several oxidoreductases utilized for pollutant degradation, has a wide range of applications due to its mild reaction conditions and high stability. Exploring efficient platforms for immobilizing g-C₃N₄ and HRP to develop photo-enzyme-coupled catalysis is an attractive practical topic. The coupling effect of g-C₃N₄ and HRP improves the carrier separation efficiency and generates more active species, which finally realize the solar-driven non-selective destruction of organic pollutants. We describe the alteration of g-C₃N₄ and the immobilization of HRP in detail in this study, and we outline recent developments in the photo-enzyme coupling of g-C₃N₄ and HRP.

In-house fabrication of macro-porous biopolymeric hydrogel and its deployment for adsorptive remediation of lead and cadmium from water matrices

A novel adsorbent was prepared by blending chitosan (CS) and acrylic acid (AA) while using formaldehyde as a cross linker in the form of hydrogel beads. The adsorption properties of these hydrogel beads for the removal of toxic metal ions (Pb²⁺ and Cd²⁺) from aqueous solutions were evaluated. The hydrogel beads have a 3D macro-porous structure whose -NH₂ groups were considered to be the dominant binding specie for Cd and Pb ions. The equilibrium adsorption capacity (q_e) of beads was significantly affected by the mass ratio of sorbent and sorbate. The percentage removal of Cd and Pb ions was observed to be enhanced with the increase in sorbate concentration. The hydrogel beads maintained good adsorption properties at adsorption-desorption equilibrium. The Langmuir and Freundlich models were used to elaborate the isotherms as well as isotherm constants. Adsorption isothermal data is well explained by the Freundlich model. The data of experimental kinetics is interrelated with the second-order kinetic model, which showed that the chemical sorption phenomenon is the rate limiting step. The results of intraparticle diffusion model described the adsorption process occurred on a porous substance that proved chitosan/Formaldehyde beads to be the favorable adsorbent.

Glow discharge plasma stabilization of azo dye on PMMA polymer

The effects of argon gas glow discharge plasma on the surface of DR1 dye-loaded PMMA polymer films are examined in this work. Plasma immobilizes the dye on the surface of polymer without using stabilizers. Argon plasma activates the surface through breaking some bonds and generation of radical sites. It affects the acrylate groups of PMMA leading to covalent bonds between dye and surface of polymer. In addition, plasma treatment and contact with ambient air may result in the creation of new polar components, such as carbonyl and carboxyl compounds and links that enhance the dye attachment to the polymer matrix. Besides, the dye adsorption on the polymer film is impacted by changes in surface topography. Furthermore, plasma modifies the dye conformation, which affects the adherence of the dye to the polymer surface through bringing the dye to the higher energy state. The chemical and topographical modification of dye-loaded PMMA films by plasma are investigated by spectroscopic and AFM methods. Furthermore, aging process was used to confirm dye retention on the polymer film after plasma modification as opposed to dye-loaded polymer film that was left untreated as a reference sample. Finally, investigated method suggests a novel and very affordable technique for fabrication of poly(MMA-co-DR1) copolymer in the form of a homogeneous surface layer.

Co-immobilized bienzyme of horseradish peroxidase and glucose oxidase on dopamine-modified cellulose-chitosan composite beads as a high-efficiency biocatalyst for degradation of acridine

Co-immobilized bienzyme biocatalysts are attracting increasing interest in the field of wastewater treatment due to their widespread application. In this study, we successfully prepared a co-immobilized bienzyme biocatalyst by immobilizing horseradish peroxidase (HRP) and glucose oxidase (GOD) on dopamine (DA) modified cellulose (Ce)-chitosan (Cs) composite beads via covalent binding, designated as Ce-Cs@DA/HRP-GOD beads, and found that the bienzyme biocatalyst had a good ability to catalytically degrade acridine in wastewater. SEM, EPR, FTIR, and XRD were used to characterise the structure and properties of the Ce-Cs@DA/HRP-GOD beads. The co-immobilized bienzyme biocatalyst with a small amount of HRP exhibited better degradation efficiency for acridine (99.5%, 8 h) in simulated wastewater compared to the Ce-Cs@DA/HRP (93.8%, 8 h) and Ce-Cs@DA/GOD (15.8%, 8 h) beads alone. In addition, a reusability study showed that the co-immobilized bienzyme biocatalyst maintained a degradation rate of 61.2% after six cycles of acridine degradation. The good biodegradability and reusability of the biocatalyst might be due to the synergistic effect of bienzyme HRP-GOD, including the strong covalent bonding. Accordingly, the co-immobilized bienzyme biocatalyst based on the cascade reaction may pave the way for efficient and eco-friendly treatment of industrial wastewater.

New Gelatin-Based Hydrogel Foams for Improved Substrate Conversion of Immobilized Horseradish Peroxidase

Hydrogel foams provide an aqueous environment that is very attractive for the immobilization of enzymes. To this end, functional polymers are needed that can be converted into hydrogel foams and that enable bioconjugation while maintaining high enzyme activity. The present study demonstrates the potential of biotinylated gelatin methacryloyl (GM10EB) for this purpose. GM10EB is synthesized in a two-step procedure with gelatin methacryloyl (GM10) being the starting point. Successful biotinylation is confirmed by 2,4,6-trinitrobenzene sulfonic acid (TNBS) and 4'-hydroxyazobenzene-2-carboxylic acid (HABA)/Avidin assays. Most importantly, a high methacryloyl group content (DM) is maintained in GM10EB, so that solutions of GM10EB show both a sufficiently low viscosity for microfluidic foaming and a pronounced curing behavior. Thus, foamed and non-foamed GM10EB hydrogels can be prepared via radical cross-linking of the polymer chains. Within both sample types, biotin groups are available for bioconjugation, as is demonstrated by coupling streptavidin-conjugated horseradish peroxidase to the hydrogels. When assessing the substrate conversion rate r_A in both foamed and non-foamed hydrogels by enzymatic conversion of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), we observed a value for r_A twelve times higher than the value for non-foamed hydrogels of the same mass. In other words, r_A can be successfully tailored by the hydrogel morphology. This article is protected by copyright. All rights reserved.

Current Trends in Biomedical Hydrogels: From Traditional Crosslinking to Plasma-Assisted Synthesis

The use of materials to restore or replace the functions of damaged body parts has been proven historically. Any material can be considered as a biomaterial as long as it performs its biological function and does not cause adverse effects to the host. With the increasing demands for biofunctionality, biomaterials nowadays may not only encompass inertness but also specialized utility towards the target biological application. A hydrogel is a biomaterial with a 3D network made of hydrophilic polymers. It is regarded as one of the earliest biomaterials developed for human use. The preparation of hydrogel is often attributed to the polymerization of monomers or crosslinking of hydrophilic polymers to achieve the desired ability to hold large amounts of aqueous solvents and biological fluids. The generation of hydrogels, however, is shifting towards developing hydrogels through the aid of enabling technologies. This review provides the evolution of hydrogels and the different approaches considered for hydrogel preparation. Further, this review presents the plasma process as an enabling technology for tailoring hydrogel properties. The mechanism of plasma-assisted treatment during hydrogel synthesis and the current use of the plasma-treated hydrogels are also discussed.

Recent advancements in encapsulation of chitosan-based enzymes and their applications in food industry

Enzymes are readily inactivated in harsh micro-environment due to changes in pH, temperature, and ionic strength. Developing suitable and feasible techniques for stabilizing enzymes in food sector is critical for preventing them from degradation. This review provides an overview on chitosan (CS)-based enzymes encapsulation techniques, enzyme release mechanisms, and their applications in food industry. The challenges and future prospects of CS-based enzymes encapsulation were also discussed. CS-based encapsulation techniques including ionotropic gelation, emulsification, spray drying, layer-by-layer self-assembly, hydrogels, and films have been studied to improve the encapsulation efficacy (EE), heat, acid and base stability of enzymes for their applications in food, agricultural, and medical industries. The smart delivery design, new delivery system development, and in vivo releasing mechanisms of enzymes using CS-based encapsulation techniques have also been evaluated in laboratory level studies. The CS-based encapsulation techniques in commercial products should be further improved for broadening their application fields. In conclusion, CS-based encapsulation techniques may provide a promising approach to improve EE and bioavailability of enzymes applied in food industry.HighlightsEnzymes play a critical role in food industries but susceptible to inactivation.Chitosan-based materials could be used to maintain the enzyme activity.Releasing mechanisms of enzymes from encapsulators were outlined.Applications of encapsulated enzymes in food fields was discussed.

Recent Advances of Stimuli-Responsive Polysaccharide Hydrogels in Delivery Systems: A Review

Hydrogels obtained from natural polymers have received widespread attention for their excellent biocompatible property, nontoxicity, easy gelation, and functionalization. Polysaccharides can regulate the gut microbiota and improve the intestinal microenvironment, thus exerting the healthy effect of intestinal immunity. In an active substance delivery system, the extent and speed of the substance reaching its target are highly dependent on the carrier. Thus, the smart active substance delivery systems are gradually increasing. The smart polysaccharide-hydrogels possess the ability in response to external stimuli through changing their volume phase and structure, which are applied in various fields. Natural polysaccharide-based hydrogels possess excellent characteristics of environmental friendliness, good biocompatibility, and abundant sources. According to the response type, natural polysaccharide-based hydrogels are usually divided into stimulus-responsive hydrogels, including internal response (pH, temperature, enzyme, redox) and external response (light, electricity, magnetism) hydrogels. The delivery system based on polysaccharides can exert their effects in the gastrointestinal tract. At the same time, polysaccharides may also take part in regulating the brain signals through the microbiota-gut-brain axis. Therefore, natural polysaccharide-hydrogels are considered as promising biomaterials, which can be designed as delivery systems for regulating the gut-brain axis. This article reviews the research advance of stimulus-responsive hydrogels, which focus on the types, response characteristics, and applications for polysaccharide-based smart hydrogels as delivery systems.

Injectable Natural Polymer Hydrogels for Treatment of Knee Osteoarthritis

Osteoarthritis (OA) is a serious chronic and degenerative disease that increasingly occurs in the aged population. Its current clinical treatments are limited to symptom relief and cannot regenerate cartilage. Although a better understanding of OA pathophysiology has been facilitating the development of novel therapeutic regimen, delivery of therapeutics to target sites with minimal invasiveness, high retention, and minimal side effects remains a challenge. Biocompatible hydrogels have been recognized to be highly promising for controlled delivery and release of therapeutics and biologics for tissue repair. In this review, the current approaches and the challenges in OA treatment, and unique properties of injectable natural polymer hydrogels as delivery system to overcome the challenges are presented. The common methods for fabrication of injectable polysaccharide-based hydrogels and the effects of their composition and properties on the OA treatment are detailed. The strategies of the use of hydrogels for loading and release cargos are also covered. Finally, recent efforts on the development of injectable polysaccharide-based hydrogels for OA treatment are highlighted, and their current limitations are discussed.

Study of Several Alginate-Based Hydrogels for In Vitro 3D Cell Cultures

Hydrogel, a special system of polymer solutions, can be obtained through the physical/chemical/enzymic crosslinking of polymer chains in a water-based dispersion medium. Different compositions and crosslinking methods endow hydrogel with diverse physicochemical properties. Those hydrogels with suitable physicochemical properties hold manifold functions in biomedical fields, such as cell transplantation, tissue engineering, organ manufacturing, drug releasing and pathological model analysis. In this study, several alginate-based composite hydrogels, including gelatin/alginate (G-A), gelatin/alginate/agarose (G-A-A), fibrinogen/alginate (F-A), fibrinogen/alginate/agarose (F-A-A) and control alginate (A) and alginate/agarose (A-A), were constructed. We researched the advantages and disadvantages of these hydrogels in terms of their microscopic structure (cell living space), water holding capacity, swelling rate, swelling-erosion ratio, mechanical properties and biocompatibility. Briefly, alginate-based hydrogels can be used for three-dimensional (3D) cell culture alone. However, when mixed with other natural polymers in different proportions, a relatively stable network with a good cytocompatibility, mechanical strength and water holding capacity can be formed. The physical and chemical properties of the hydrogels can be adjusted by changing the composition, proportion and cross-linking methods of the polymers. Conclusively, the G-A-A and F-A-A hydrogels are the best hydrogels for the in vitro 3D cell cultures and pathological model construction.

Synthesis of two novel bio-based hydrogels using sodium alginate and chitosan and their proficiency in physical immobilization of enzymes

Herein, four novel and bio-based hydrogel samples using sodium alginate (SA) and chitosan (CH) grafted with acrylamide (AAm) and glycidyl methacrylate (GMA) and their reinforced nanocomposites with graphene oxide (GO) were synthesized and coded as SA-g-(AAm-co-GMA), CH-g-(AAm-co-GMA), GO/SA-g-(AAm-co-GMA), and GO/CH-g-(AAm-co-GMA), respectively. The morphology, net charge, and water absorption capacity of samples were entirely changed by switching the biopolymer from SA to CH and adding a nano-filler. The proficiencies of hydrogels were compared in the immobilization of a model metagenomic-derived xylanase (PersiXyn9). The best performance was observed for GO/SA-g-poly(AAm-co-GMA) sample indicating better stabilizing electrostatic attractions between PersiXyn9 and reinforced SA-based hydrogel. Compared to the free enzyme, the immobilized PersiXyn9 on reinforced SA-based hydrogel showed a 110.1% increase in the released reducing sugar and almost double relative activity after 180 min storage. While immobilized enzyme on SA-based hydrogel displayed 58.7% activity after twelve reuse cycles, the enzyme on CH-based carrier just retained 8.5% activity after similar runs.

Peroxidase enzymes as green catalysts for bioremediation and biotechnological applications: A review

The fast-growing consumer demand drives industrial process intensification, which subsequently creates a significant amount of waste. These products are discharged into the environment and can affect the quality of air, degrade water streams, and alter soil characteristics. Waste materials may contain polluting agents that are especially harmful to human health and the ecosystem, such as the synthetic dyes, phenolic agents, polycyclic aromatic hydrocarbons, volatile organic compounds, polychlorinated biphenyls, pesticides and drug substances. Peroxidases are a class oxidoreductases capable of performing a wide variety of oxidation reactions, ranging from reactions driven by radical mechanisms, to oxygen insertion into CH bonds, and two-electron substrate oxidation. This versatility in the mode of action presents peroxidases as an interesting alternative in cleaning the environment. Herein, an effort has been made to describe mechanisms governing biochemical process of peroxidase enzymes while referring to H₂O₂/substrate stoichiometry and metabolite products. Plant peroxidases including horseradish peroxidase (HRP), soybean peroxidase (SBP), turnip and bitter gourd peroxidases have revealed notable biocatalytic potentialities in the degradation of toxic products. On the other hand, an introduction on the role played by ligninolytic enzymes such as manganese peroxidase (MnP) and lignin peroxidase (LiP) in the valorization of lignocellulosic materials is addressed. Moreover, sensitivity and selectivity of peroxidase-based biosensors found use in the quantitation of constituents and the development of diagnostic kits. The general merits of peroxidases and some key prospective applications have been outlined as concluding remarks.

A critical review on the treatment of dye-containing wastewater: Ecotoxicological and health concerns of textile dyes and possible remediation approaches for environmental safety

The synthetic dyes used in the textile industry pollute a large amount of water. Textile dyes do not bind tightly to the fabric and are discharged as effluent into the aquatic environment. As a result, the continuous discharge of wastewater from a large number of textile industries without prior treatment has significant negative consequences on the environment and human health. Textile dyes contaminate aquatic habitats and have the potential to be toxic to aquatic organisms, which may enter the food chain. This review will discuss the effects of textile dyes on water bodies, aquatic flora, and human health. Textile dyes degrade the esthetic quality of bodies of water by increasing biochemical and chemical oxygen demand, impairing photosynthesis, inhibiting plant growth, entering the food chain, providing recalcitrance and bioaccumulation, and potentially promoting toxicity, mutagenicity, and carcinogenicity. Therefore, dye-containing wastewater should be effectively treated using eco-friendly technologies to avoid negative effects on the environment, human health, and natural water resources. This review compares the most recent technologies which are commonly used to remove dye from textile wastewater, with a focus on the advantages and drawbacks of these various approaches. This review is expected to spark great interest among the research community who wish to combat the widespread risk of toxic organic pollutants generated by the textile industries.

Recombinant Arthromyces ramosus Peroxidase Has Similar Substrate Specificity Profiles as, but a Catalytic Efficiency up to 11-Fold Higher than, Horseradish Peroxidase

Fungal peroxidases are valuable enzymes. Arthromyces ramosus peroxidase (ARP) and horseradish peroxidase (HRP) share a conserved catalytic site. Both native ARP and recombinant ARP (rARP) were not commercially available. The substrate specificity and kinetic parameters of rARP and HRP were not well compared, particularly relevent to structure-activity relationship. In this work, rARP expressed by Komagataella phaffii had a production yield of 6.2 mg/L, up to 155-fold higher than ARP and other recombinant peroxidases, and a specific activity of 3240 units/mg toward 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), up to 29-fold higher than HRP and other peroxidases. The Michaelis constant (K_m) and first-order rate constant (k_cat) of rARP showed 10-fold substrate affinity and consequently 6-fold catalytic efficiency of HRP toward ABTS. Under optimal conditions, rARP shared similar substrate specificity profiles as commercial HRP; the second-order rate constants (k_app) of rARP showed 2-11-fold catalytic efficiency of HRP toward well-known peroxidase substrates. rARP's higher catalytic efficiency was also in agreement with the shorter binding distance of H/N-His⁵⁶ in rARP/substrate in comparison to that of HRP/substrate, as illustrated by docking simulation. The rARP had similar substrate specificity profiles as, but higher specific activity and catalytic efficiency than, HRP, which merits its further structure-functional characterization and applications.

ABTS as an electron shuttle to accelerate the degradation of diclofenac with horseradish peroxidase-catalyzed hydrogen peroxide oxidation

Horseradish peroxidase (HRP)-catalyzed hydrogen peroxide (H₂O₂) oxidation could degrade a variety of organic pollutants, but the intrinsic drawback of slow degradation rate limited its widespread application. In this study, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) was introduced into HRP/H₂O₂ system as an electron shuttle to enhance diclofenac degradation under neutral pH conditions. The green-colored ABTS radical (ABTS^•+), generated by the oxidation of ABTS with HRP-catalyzed H₂O₂ oxidation, was proved to be the main reactive species for the rapid degradation of diclofenac in HRP/H₂O₂/ABTS system. There was no destruction of ABTS/ABTS^•+ in HRP/H₂O₂/ABTS system, and ABTS was verified as an ideal electron shuttle. The reaction conditions including solution pH (4.5-10.5), HRP concentration (0-8 units mL^-1) and H₂O₂ concentration (0-500 μM) would impact the formation of ABTS^•+, and affect the degradation of diclofenac in HRP/H₂O₂/ABTS system. Moreover, compared with Fenton and hydroxylamine/Fenton systems, HRP/H₂O₂/ABTS system had better diclofenac degradation efficiency, higher H₂O₂ utilization efficiency and stronger anti-interference capacity in actual waters. Overall, the present study provided a meaningful and promising way to enhance the degradation of organic pollutants in water with HRP-catalyzed H₂O₂ oxidation.

Nanobiocatalysts and photocatalyst in dye degradation

In the modern era, the world today is in a mission for a new method of environmental bioremediation in faltering the damage, especially in polluted water. Recently, the global direction is regulated toward an alteration from the usual chemical-based methods to a supplementary ecofriendly green alternative. In this perspective, biocatalysts are appreciated as an economical and clean substitute which was meant to catalyze degradation of unmanageable chemicals in a rapid, green and ecologically stable manner. Among the various sources of water pollution, the textile manufacturing industries were thought to be a major dispute due to release of effluents in natural water bodies such as rivers. Other industries like paper, pulp and tannery pharmaceutical industries were also responsible in contaminating the water bodies. Photocatalysis was considered as an auspicious method for the removal of dyes from the natural bodies, specifically those with hard organic compounds; using enzymes. The present chapter briefly emphasizes on the effective methods used for degradation of dye effluents; their importance of photocatalytic and biocatalytic solution to the current environmental difficulties and future opportunities are discussed.

A review on the microbial degradation of chlorpyrifos and its metabolite TCP

Chlorpyrifos (CPF) falls under the category of organophosphorus pesticides which are in huge demand in the agricultural sector. Overuse of this pesticide has led to the degradation of the quality of terrestrial and aquatic life. The chemical is moderately persistent in the environment but its primary metabolite 3,5,6-trichloro-2-pyridinol (TCP) is comparatively highly persistent. Thus, it is important to degrade the chemical and there are many proposed techniques of degradation. Out of which bioremediation is considered to be highly cost-effective and efficient. Many previous studies have attempted to isolate appropriate microbial strains to degrade CPF which established the fact that chlorine atoms released while mineralising TCP inhibits further proliferation of microorganisms. Thus, it has been increasingly important to experiment with strains that can simultaneously degrade both CPF and TCP. In this review paper, the need for degrading CPF specifically the problems related to it has been discussed elaborately. Alongside these, the metabolism pathways undertaken by different kinds of microorganisms have been included. This paper also gives a detailed insight into the potential strains of microorganisms which has been confirmed through experiments conducted previously. It can be concluded that a wide range of microorganisms has to be studied to understand the possibility of applying bioremediation in wastewater treatment to remove pesticide residues. In addition to this, in the case of recalcitrant pesticides, options of treating it with hybrid techniques like bioremediation clubbed with photocatalytic biodegradation can be attempted.

Enzyme (Single and Multiple) and Nanozyme Biosensors: Recent Developments and Their Novel Applications in the Water-Food-Health Nexus

The use of sensors in critical areas for human development such as water, food, and health has increased in recent decades. When the sensor uses biological recognition, it is known as a biosensor. Nowadays, the development of biosensors has been increased due to the need for reliable, fast, and sensitive techniques for the detection of multiple analytes. In recent years, with the advancement in nanotechnology within biocatalysis, enzyme-based biosensors have been emerging as reliable, sensitive, and selectively tools. A wide variety of enzyme biosensors has been developed by detecting multiple analytes. In this way, together with technological advances in areas such as biotechnology and materials sciences, different modalities of biosensors have been developed, such as bi-enzymatic biosensors and nanozyme biosensors. Furthermore, the use of more than one enzyme within the same detection system leads to bi-enzymatic biosensors or multi-enzyme sensors. The development and synthesis of new materials with enzyme-like properties have been growing, giving rise to nanozymes, considered a promising tool in the biosensor field due to their multiple advantages. In this review, general views and a comparison describing the advantages and disadvantages of each enzyme-based biosensor modality, their possible trends and the principal reported applications will be presented.

Expanding the bio-catalysis scope and applied perspectives of nanocarrier immobilized asparaginases

l-asparaginase is an essential enzyme in medicine and a well-known chemotherapeutic agent. This enzyme's importance is not limited to its use as an anti-cancer agent; it also has a wide variety of medicinal applications. Antimicrobial properties, prevention of infectious disorders, autoimmune diseases, and canine and feline cancer are among the applications. Apart from the healthcare industry, its importance has been identified in the food industry as a food manufacturing agent to lower acrylamide levels. When isolated from their natural habitats, they are especially susceptible to different denaturing conditions due to their protein composition. The use of an immobilization technique is one of the most common approaches suggested to address these limitations. Immobilization is a technique that involves fixing enzymes to or inside stable supports, resulting in a heterogeneous immobilized enzyme framework. Strong support structures usually stabilize the enzymes' configuration, and their functions are maintained as a result. In recent years, there has been a lot of curiosity and focus on the ability of immobilized enzymes. The nanomaterials with ideal properties can be used to immobilize enzymes to regulate key factors that determine the efficacy of bio-catalysis. With applications in biotechnology, immunosensing, biomedicine, and nanotechnology sectors have opened a realm of opportunities for enzyme immobilization.

Hydrogel Preparation Methods and Biomaterials for Wound Dressing

Wounds have become one of the causes of death worldwide. The metabolic disorder of the wound microenvironment can lead to a series of serious symptoms, especially chronic wounds that bring great pain to patients, and there is currently no effective and widely used wound dressing. Therefore, it is important to develop new multifunctional wound dressings. Hydrogel is an ideal dressing candidate because of its 3D structure, good permeability, excellent biocompatibility, and ability to provide a moist environment for wound repair, which overcomes the shortcomings of traditional dressings. This article first briefly introduces the skin wound healing process, then the preparation methods of hydrogel dressings and the characteristics of hydrogel wound dressings made of natural biomaterials and synthetic materials are introduced. Finally, the development prospects and challenges of hydrogel wound dressings are discussed.

Peroxidase driven micromotors for dynamic bioremediation

Phenolics are size products present in tons concentrations in industrial wastewater that can cause adverse health effects when released in the environment. As such, there is a growing interest in the development of efficient strategies for the removal of phenolic compounds from polluted water. Herein we describe the use of poly(3,4-ethylenedioxythiophene) (PEDOT)-Au/peroxidase micromotors as dynamic biocatalytic platforms for the removal of model phenolics (phenol, bisphenol A, guaiacol, pyrogallol and catechol). Micromotors are synthetized by using a simplified template electrodeposition protocol followed by covalent enzyme immobilization in the inner Au layer. Kinetic parameters revealed that enzyme immobilization in the inner micromotor layer increased over 2-fold the enzymatic activity, along with increasing operational pH and thermal stabilities. The micromotors can propel at speed of up to 60 µm/s, generating an enhanced fluid mixing that results in removal efficiencies of up to 60% as compared with the 27% removal when using free peroxidase under the same conditions. In addition, excellent activities of almost 100% were obtained within ten cycles of removal using the micromotors. This newly developed bioremediation strategy holds considerable promise in for its application in large scale water treatment systems and many relevant environmental processes.

Role of chitosan-based hydrogels in pollutants adsorption and freshwater harvesting: A critical review

The shortage of freshwater resources is an urgent problem worldwide, especially for some areas that lack rainfall conditions. The development of reliable wastewater treatment and freshwater harvesting equipment has become an urgent demand. Hydrogel is a porous 3D network structure with good pollutant adsorption capacity, water holding capacity, water adsorption capacity, and reversible swelling ability, which has been widely used in water treatment. Chitosan (CH), as the abundant bioactive material in nature, is commonly used to prepare hydrogels with low-cost, favorable stability, good antimicrobial activity, high mechanical properties, biodegradability, and environmental friendliness. Therefore, this review presents a comprehensive review of the various applications of CH-based hydrogels in water treatment including various pollutant adsorption, oil-water separation, seawater desalination, and atmospheric condensation. The relevant mechanisms, application potential, and challenge are also illustrated. This review aims to provide a viable idea to address the shortage of freshwater resources.

Exploring current tendencies in techniques and materials for immobilization of laccases - A review

Nanotechnology has transformed the science behind many biotechnological sectors, and applied bio-catalysis is not the exception. In 2017, the enzyme industry was valued at more than 7 billion USD and projected to 10.5 billion by 2024. The laccase enzyme is an oxidoreductase capable of oxidizing phenolic and non-phenolic compounds that have been considered an essential tool in the fields currently known as white biotechnology and green chemistry. Laccase is one of the most robust biocatalysts due to its wide applications in different environmental processes such as detecting and treating chemical pollutants and dyes and pharmaceutical removal. However, these biocatalytic processes are usually limited by the lack of stability of the enzyme, the half-life time, and the application feasibility at an industrial scale. Physical or chemical approaches have performed different laccase's immobilization methods to improve its catalytic properties and reuse. Emerging technologies have been proven to reduce the manufacturing process cost and increase application feasibility while looking for ecological and economical materials that can be used as support. Therefore, this review discusses the trends of enzyme immobilization recently studied, analyzing biomaterials and agro-industrial waste used for that intention, their advantages, and disadvantages. Finally, the work also highlights the performance obtained with these materials and current challenges and potential alternatives.

Recent advances in composite hydrogels prepared solely from polysaccharides

The proliferating demand for sustainable, biodegradable, and biologically safe materials has triggered the development of polysaccharide-based hydrogels. The translation of research on single polysaccharide-based hydrogels into their desired clinical or industrial application is minimal. This is attributable to their lack of mechanical strength, inadequate stability, and constrained the possibility of their modulation to obtain the desired property. Polysaccharide-based composite hydrogels (PCHs) have proven their mantle to counteract this issue while expanding the horizons for their applications. PCHs can be fabricated by physical and/or chemical interlinking techniques, which entails the association of macromolecular chain linkages. The resulting composites can impart remarkably higher stability and elevate the suitability and efficiency of the system. Owing to these advantages, the research on PCHs has been gaining momentum. They are emerging as a lucrative alternative for the conventional molecules used for the fabrication of such materials. The review would initially focus on providing a detailed outlook for the various physical/chemical techniques involved in the preparation of PCHs. Subsequently, the characterization techniques used to understand the structural and chemical behavior of PCHs would be discussed. The article would also elaborate on the various fields of application and the possible areas for future research of PCHs.

Biocatalytic remediation of industrial pollutants for environmental sustainability: Research needs and opportunities

An increasing quantum of pollutants from various industrial sector activities represents a severe menace to environmental & ecological balance. Bioremediation is gaining flow globally due to its cost-effective and environment-friendly nature. Understanding biodegradation mechanisms is of high ecological significance. Application of microbial enzymes has been reported as sustainable approach to mitigate the pollution. Immobilized enzyme catalyzed transformations are getting accelerated attention as potential alternatives to physical and chemical methods. The attention is now also focused on developing novel protein engineering strategies and bioreactor design systems to ameliorate overall biocatalysis and waste treatment further. This paper presents and discusses the most advanced and state of the art scientific & technical developments about biocatalytic remediation of industrial pollutants. It also covers various biocatalysts and the associated sustainable technologies to remediate various pollutants from waste streams. Enzyme production and immobilization in bioreactors have also been discussed. This paper also covers challenges and future research directions in this field.