Synthesis of Phenylboronic Acid-Functionalized Magnetic Nanoparticles for Sensitive Soil Enzyme Assays

Abstract

Soil enzymes, such as invertase, urease, acidic phosphatase and catalase, play critical roles in soil biochemical reactions and are involved in soil fertility. However, it remains a great challenge to efficiently concentrate soil enzymes and sensitively assess enzyme activity. In this study, we synthesized phenylboronic acid-functionalized magnetic nanoparticles to rapidly capture soil enzymes for sensitive soil enzyme assays. The iron oxide magnetic nanoparticles (MNPs) were firstly prepared by the co-precipitation method and then functionalized by (3-aminopropyl)triethoxysilane, polyethyleneimine and phenylboric acid in turn, obtaining the final nanoparticles (MNPPBA). Protein-capturing assays showed that the functionalized MNPs had a much higher protein-capturing capacity than the naked MNPs (56% versus 6%). Moreover, MNPPBA almost thoroughly captured the tested enzymes, i.e., urease, invertase, and alkaline phosphatase, from enzyme solutions. Based on MNPPBA, a soil enzyme assay method was developed by integration of enzyme capture, magnetic separation and trace enzyme analysis. The method was successfully applied in determining trace enzyme activity in rhizosphere soil. This study provides a strategy to sensitively determine soil enzyme activity for mechanistic investigation of soil fertility and plant–microbiome interaction.

Growth and Physiological Characteristics of Sour Jujube Seedlings in Different Substrate Formulations

“…The enzyme activity of rhizosphere substrate, closely related to the growth and development of seedlings, has the function of accelerating soil biochemical reactions, and plays an important role in the ecosystem. Its activity is closely related to soil physical and chemical properties and environmental conditions, etc., and is regarded as an early warning indicator of changes in soil quality [15]. The role of urease is, specifically, to catalyze the breakdown of urea to ammonium and carbonic acid [16], with significant differences in enzyme activity between substrates (Figure 2).…”

Analysis of the Effects of Windthrows on the Microbiological Properties of the Forest Soils and Their Natural Regeneration

“…To assess the intensity of microbial activity in soil, the activity of specific enzymes [23] such as sucrase [24], amylase [25], glucosidase [26], urease [27], dehydrogenase [28], catalase [29], phosphatase [30], etc., are determined. Among all soil enzymes, dehydrogenases are one of the most important and are used as an indicator of the overall microbial activity of the soil, because they are produced by soil microorganisms intracellularly and capable of multiplication.…”

“…The relatively simple methodology for determining the biological properties of forest soils has led to a large number of scientific studies on carbon sequestration, enzymatic activity, and fungal communities [7,8,[11][12][13][14][15]20,22,26,29,[31][32][33][34][51][52][53][54]. However, when it comes to forest soils, the number of studies decreases [10,[16][17][18][19]23,27,28,36,38,[55][56][57][58], and even more so in the case of forest soils affected by various natural or anthropogenic disturbances [21,35,43,[59][60][61]. The number of studies is particularly limited for soils in areas affected by windthrow events [62][63][64][65][66].…”