Particle Size Measurement and Detection of Bound Proteins of Non-Porous/Mesoporous Silica Microspheres by Single-Particle Inductively Coupled Plasma Mass Spectrometry

Single-particle inductively coupled plasma mass spectrometry (spICP-MS) has been used for particle size measurement of diverse types of individual nanoparticles and micrometer-sized carbon-based particles such as microplastics. However, its applicability to the measurement of micrometer-sized non-carbon-based particles such as silica (SiO2) particles is unclear. In this study, the applicability of spICP-MS to particle size measurement of non-porous/mesoporous SiO2 microspheres with a nominal diameter of 5.0 µm or smaller was investigated. Particle sizes of these microspheres were measured using both spICP-MS based on a conventional calibration approach using an ion standard solution and scanning electron microscopy as a reference technique, and the results were compared. The particle size distributions obtained using both techniques were in agreement within analytical uncertainty. The applicability of this technique to the detection of metal-containing protein-binding mesoporous SiO2 microspheres was also investigated. Bound iron (Fe)-containing proteins (i.e., lactoferrin and transferrin) of mesoporous SiO2 microspheres were detected using Fe as a presence marker for the proteins. Thus, spICP-MS is applicable to the particle size measurement of large-sized and non-porous/mesoporous SiO2 microspheres. It has considerable potential for element-based detection and qualification of bound proteins of mesoporous SiO2 microspheres in a variety of applications.

Highly Precise and Sensitive Polymerase Chain Reaction Using Mesoporous Silica-Immobilized Enzymes

A highly precise and sensitive technology that enables DNA amplification/detection from minimal amounts of nucleic acid is expected to find applicability in genetic testing involving small amounts of samples. The use of a free enzyme in conventional DNA amplification techniques, such as the polymerase chain reaction (PCR), frequently causes side reactions (i.e., nonspecific DNA amplification) when ≤10³ substrate DNA molecules are present, thereby preventing selective amplification of the target DNA. To address this issue, we have developed a novel DNA amplification system, mesoporous silica-enhanced PCR (MSE-PCR), which involves the immobilization of a thermostable DNA polymerase from Thermococcus kodakaraensis (KOD DNA polymerase) into highly ordered nanopores of the mesoporous silica to control the reaction environment around the enzyme. In the MSE-PCR system using immobilized KOD DNA polymerase, such nonspecific DNA amplification was remarkably inhibited under the same conditions. Furthermore, the optimization of mesoporous silica pore sizes enabled selective and efficient DNA amplification from DNA substrates at the single-molecule level, i.e., one ten-thousandth of the amount of substrate DNA required for a DNA amplification reaction using a free enzyme. The results obtained in this study have shown that the nanopores of mesoporous silica can inhibit nonspecific reactions in DNA amplification, thereby considerably improving the specificity and sensitivity of the DNA polymerase reaction.

Permeabilization and immobilization of whole-cell Pseudomonas nitroreducens SP.001 to improve its l-glutaminase performance

BACKGROUND

L-Glutaminase is considered to be an important industrial enzyme in both the pharmaceutical and food industries, especially for producing functional glutamyl compounds, such as l-theanine. Pseudomonas nitroreducens SP.001 with intracellular l-glutaminase activity has been screened previously. In the present study, three physical permeabilization methods were used to improve l-glutaminase activity. Then, the whole-cell immobilization conditions of permeabilized cells using sodium alginate as an embedding agent were optimized to enhance the enzyme's stability and reusability. The characteristics of the immobilized cells were investigated in comparison with those of permeabilized cells.

RESULTS

The results obtained showed that cell permeabilization using osmotic shock with 155 g L^-1 sucrose markedly improved enzyme activity. Then, an effective procedure for immobilization of permeabilized P. nitroreducens cells was established. The optimum conditions for cell immobilization were: sodium alginate 40 g L^-1 , calcium chloride 30 g L^-1 , cell mass 100 g L^-1 and a curing time of 3 h. After successful immobilization, characterization studies revealed that the thermostability and pH resistance of l-glutaminase from immobilized cells were enhanced compared to those from permeabilized cells. Moreover, the immobilized biocatalyst could be reused up to 10 times and retained 80% of its activity.

CONCLUSION

The stability and reusability of the permeabilized cells were improved through the immobilization. These findings indicated that immobilized whole-cell l-glutaminase from P. nitroreducens SP.001 possesses more potential for various industrial biotechnological applications than free cells. © 2020 Society of Chemical Industry.

From Tea Leaves to Factories: A Review of Research Progress in l-Theanine Biosynthesis and Production

l-Theanine is the most popular nonprotein amino acid contained in tea leaves. It is one of the umami components of green tea, contributing to the unique flavor of tea. Because of its various health functions, l-theanine has been commercially developed as a valuable ingredient easily used for various applications in food and pharmaceutical industries. Nowadays, l-theanine is mass-produced by plant extraction, chemical synthesis, or enzymatic transformation in factories. This review embodies the available up to date information on the l-theanine synthesis metabolism in the tea plant as well as approaches to produce it, placing emphasis on the biotransformation of l-theanine. It also gives insight into the challenges of l-theanine production on a large scale, as well as directions for future research. This review comprehensively summarizes information on l-theanine to provide an approach for an in-depth study of l-theanine production.

Recent advances in microbial glutaminase production and applications-a concise review

This article focuses on significant advances in the production and applications of microbial glutaminases and provides insight into the structures of different glutaminases. Glutaminases catalyze the deamidation of glutamine to glutamic acid, and this unique ability forms the basis of their applications in various industries such as pharmaceutical and food organizations. Microbial glutaminases from bacteria, actinomycetes, yeast, and fungi are of greater significance than animal glutaminases because of their stability, affordability, and ease of production. Owing to these notable benefits, they are considered to possess considerable potential in anticancer and antiviral therapy, flavor enhancers in oriental foods, biosensors and in the production of a nutraceutical theanine. This review also aims to fully explore the potential of microbial glutaminases and to set the pace for future prospects.

Machine-Assisted Organic Synthesis

In this Review we describe how the advent of machines is impacting on organic synthesis programs, with particular emphasis on the practical issues associated with the design of chemical reactors. In the rapidly changing, multivariant environment of the research laboratory, equipment needs to be modular to accommodate high and low temperatures and pressures, enzymes, multiphase systems, slurries, gases, and organometallic compounds. Additional technologies have been developed to facilitate more specialized reaction techniques such as electrochemical and photochemical methods. All of these areas create both opportunities and challenges during adoption as enabling technologies.

High-efficiency nano/micro-reactors for protein analysis

This article reviews the recent advances regarding the development of nanomaterial-based nanoreactors and microfluidic droplet reactors and their applications in protein analysis.

Nanoporous scaffold for DNA polymerase: pore-size optimisation of mesoporous silica for DNA amplification

The simple and selective immobilisation of a thermostable DNA polymerase on mesoporous silicas was achieved, and DNA amplification activity was retained under the pore-size regulation of the mesoporous silicas.