Creating a Chia and Algae-Based Material to Clean Up Pollutants

Phil Stevens
18th January, 2024

Creating a Chia and Algae-Based Material to Clean Up Pollutants

SEM micro-images of the prepared ACG-polymeric support (A) and immobilized ACG-HRP (B).

Image adapted from: Mohamed et al. / CC BY (Source)
Enzymes are biological catalysts – they speed up chemical reactions in living organisms. Horseradish peroxidase (HRP) is a commonly used enzyme with applications in various industries, including environmental remediation and biotechnology. However, HRP is relatively unstable and expensive to use in its natural, soluble form. Immobilization – attaching the enzyme to a solid support – can improve its stability, allow for easy recovery and reuse, and enhance its activity. Researchers at the National Research Centre, Egypt, have been investigating new materials for HRP immobilization[1]. The study focused on creating a composite material from chia gum (CG) and alginate (A) to serve as a support for HRP. Chia gum is a natural polysaccharide derived from chia seeds, known for its unique molecular structure. Alginate, extracted from seaweed, forms a gel-like structure when combined with certain ions. The combination of these two materials was designed to create a robust and supportive matrix for the enzyme. The researchers found that a mixture of 1.0% chia gum and 2% alginate at a pH of 7.0 provided the best results, achieving a 75% immobilization recovery – meaning 75% of the enzyme was successfully attached to the material. The resulting material, termed ACG-HRP, was then characterized using several techniques. Fourier Transform Infrared (FTIR) spectroscopy confirmed the successful interaction between the enzyme and the chia gum/alginate matrix. Scanning Electron Microscopy (SEM) revealed the physical structure of the composite, and Thermogravimetric Analysis (TGA) assessed its thermal stability. Importantly, ACG-HRP demonstrated improved properties compared to the free, soluble HRP. It retained 60% of its initial activity after ten uses, indicating good reusability. The optimal pH for ACG-HRP activity shifted to a more acidic range (pH 6.0) compared to soluble HRP (pH 7.0). The temperature optimum also increased from 40°C to 50°C, and the thermal stability range broadened from 30-40°C to 30-50°C. These changes suggest that the immobilization process protects the enzyme from denaturation – a process where the enzyme loses its shape and function due to heat or pH changes. Interestingly, similar improvements in thermal stability were observed when HRP was immobilized on modified starch[2]. The study also investigated the enzyme’s affinity for its substrates – the molecules it acts upon. ACG-HRP showed a lower affinity for hydrogen peroxide (H2O2) and guaiacol, but a higher affinity for other phenolic compounds. This altered affinity could be beneficial in specific applications where the enzyme needs to target particular pollutants. This is consistent with findings from studies on garden cress peroxidases, where different peroxidase types exhibited varying affinities for phenolic compounds[3]. The garden cress study identified a peroxidase (GCP2) with a high affinity for lignin monomers and phenolic acids, suggesting that enzyme affinity can be tailored through natural variations or immobilization techniques. Furthermore, ACG-HRP exhibited increased resistance to various inhibitors, including heavy metals, isopropanol, urea, and Triton X-100. This enhanced resistance is crucial for real-world applications where the enzyme might be exposed to harsh conditions. Similar protective effects against inhibitors were observed when HRP was immobilized on polyaniline-grafted polyacrylonitrile films[4]. The ACG-HRP also demonstrated improved efficiency in removing phenol and p-chlorophenol from solutions, highlighting its potential for environmental cleanup. This aligns with the findings from the garden cress peroxidase study[3], which showed that a specific peroxidase (GCP2) was effective at removing phenol and p-chlorophenol. The success of the chia gum/alginate matrix lies in its ability to provide a stable and protective environment for the enzyme, while also modifying its properties to enhance its performance. The combination of a distinctive polysaccharide structure from chia gum and the three-dimensionally cross-linked structure of alginate creates a potent matrix for enzyme immobilization.

EnvironmentBiotechBiochem

References

Main Study

1) Development of chia gum/alginate-polymer support for horseradish peroxidase immobilization and its application in phenolic removal.

Published 16th January, 2024

https://doi.org/10.1038/s41598-024-51566-x

Related Studies

2) Immobilization of horseradish peroxidase on cationic microporous starch: Physico-bio-chemical characterization and removal of phenolic compounds.

https://doi.org/10.1016/j.ijbiomac.2021.03.171

3) Purification and characterization of peroxidases from garden cress sprouts and their roles in lignification and removal of phenol and p-chlorophenol.

https://doi.org/10.1111/jfbc.13526

4) Cross-linking of horseradish peroxidase adsorbed on polycationic films: utilization for direct dye degradation.

https://doi.org/10.1007/s00449-012-0724-2


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