Improvement in the Cleaning Performance Towards Protein Soils in Laundry Detergents by Protease Immobilization on the Silica Nanoparticles

Proteases immobilized on nanomaterials for biocatalytic, environmental and biomedical applications: Advantages and drawbacks

Proteases have gained significant scientific and industrial interest due to their unique biocatalytic characteristics and broad-spectrum applications in different industries. The development of robust nanobiocatalytic systems by attaching proteases onto various nanostructured materials as fascinating and novel nanocarriers has demonstrated exceptional biocatalytic performance, substantial stability, and ease of recyclability over multiple reaction cycles under different chemical and physical conditions. Proteases immobilized on nanocarriers may be much more resistant to denaturation caused by extreme temperatures or pH values, detergents, organic solvents, and other protein denaturants than free enzymes. Immobilized proteases may present a lower inhibition. The use of non-porous materials in the immobilization prevents diffusion and steric hindrances during the binding of the substrate to the active sites of enzymes compared to immobilization onto porous materials; when using very large or solid substrates, orientation of the enzyme must always be adequate. The advantages and problems of the immobilization of proteases on nanoparticles are discussed in this review. The continuous and batch reactor operations of nanocarrier-immobilized proteases have been successfully investigated for a variety of applications in the leather, detergent, biomedical, food, and pharmaceutical industries. Information about immobilized proteases on various nanocarriers and nanomaterials has been systematically compiled here. Furthermore, different industrial applications of immobilized proteases have also been highlighted in this review.

Industrial applications of immobilized nano-biocatalysts

Immobilized enzyme-based catalytic constructs could greatly improve various industrial processes due to their extraordinary catalytic activity and reaction specificity. In recent decades, nano-enzymes, defined as enzyme immobilized on nanomaterials, gained popularity for the enzymes' improved stability, reusability, and ease of separation from the biocatalytic process. Thus, enzymes can be strategically incorporated into nanostructured materials to engineer nano-enzymes, such as nanoporous particles, nanofibers, nanoflowers, nanogels, nanomembranes, metal-organic frameworks, multi-walled or single-walled carbon nanotubes, and nanoparticles with tuned shape and size. Surface-area-to-volume ratio, pore-volume, chemical compositions, electrical charge or conductivity of nanomaterials, protein charge, hydrophobicity, and amino acid composition on protein surface play fundamental roles in the nano-enzyme preparation and catalytic properties. With proper understanding, the optimization of the above-mentioned factors will lead to favorable micro-environments for biocatalysts of industrial relevance. Thus, the application of nano-enzymes promise to further strengthen the advances in catalysis, biotransformation, biosensing, and biomarker discovery. Herein, this review article spotlights recent progress in nano-enzyme development and their possible implementation in different areas, including biomedicine, biosensors, bioremediation of industrial pollutants, biofuel production, textile, leather, detergent, food industries and antifouling.

Analysis of Cleaning Process for Several Kinds of Soil by Probability Density Functional Method

A method of analyzing the detergency of various soils by assuming normal distributions for the soil adhesion and soil removal forces was developed by considering the relationship between the soil type and the distribution profile of the soil removal force. The effect of the agitation speed on the soil removal was also analyzed by this method. Washing test samples were prepared by soiling fabrics with individual soils such as particulate soils, oily dyes, and water-soluble dyes. Washing tests were conducted using a Terg-O-Tometer and four repetitive washing cycles of 5 min each. The transition of the removal efficiencies was recorded in order to calculate the mean value (μ_rl) and the standard deviation (σ_rl) of the removal strength distribution. The level of detergency and the temporal alteration in the detergency can be represented by μ_rl and σ_rl, respectively. A smaller σ_rl indicates a smaller increase in the detergency with time, which also indicates the existence of a certain amount of soil with a strong adhesion force. As a general trend, the values of σ_rl were the greatest for the oily soils, followed by those of the water-soluble soils and particulate soils in succession. The relationship between the soil removal processes and the soil adhesion force was expressed on the basis of the transition of the distribution of residual soil. Evaluation of the effects of the agitation speed on µ_rl and ơ_rl showed that σ_rl was not affected by the agitation speed; the value of µ_rl for solid soil and oily soil increased with increasing agitation, and the µ_rl of water-soluble soil was not specifically affected by the agitation speed. It can be assumed that the parameter ơ_rl is related to the characteristics of the soil and the adhesion condition, and can be applied to estimating the soil removal mechanism.