Recent Developments in Innovative Magnetic Nanoparticles-Based Immunoassays: From Improvement of Conventional Immunoassays to Diagnosis of COVID-19.

During the ongoing COVID-19 pandemic, the development of point-of-care (POC) detection with high sensitivity and rapid detection time is urgently needed to prevent transmission of infectious diseases. Magnetic nanoparticles (MNPs) have been considered attractive materials for enhancing sensitivity and reducing the detection time of conventional immunoassays due to their unique properties including magnetic behavior, high surface area, excellent stability, and easy biocompatibility. In addition, detecting target analytes through color development is necessary for user-friendly POC detection. In this review, recent advances in different types of MNPs-based immunoassays such as improvement of the conventional enzyme-linked immunosorbent assay (ELISA), immunoassays based on the peroxidase-like activity of MNPs and based on the dually labeled MNPs, filtration method, and lateral-flow immunoassay are described and we analyze the advantages and strategies of each method. Furthermore, immunoassays incorporating MNPs for COVID-19 diagnosis through color development are also introduced, demonstrating that MNPs can become common tools for on-site diagnosis.

Continuous VOCs Monitoring in Saturated and Unsaturated Zones Using Thermal Desorber and Gas Chromatography: System Development and Field Application.

Subsurface VOC monitoring has been mainly based on manual sampling, transport, and analysis, which would require a sufficient amount of samples to ensure data accuracy and reliability, and additional costs to ensure sample quality. Therefore, a continuous on-site monitoring system is desirable for accurate measurement and subsequent risk assessment. In this study, benzene, toluene, ethylbenzene, and xylene (BTEX) were continuously monitored by the system based on a thermal desorber (TD) and gas chromatography (GC) in an oil-contaminated site that consisted of saturated and unsaturated zones. For the saturated zone, fully automated groundwater sampling and purging processes were performed, and the gasified samples were applied to the TD-GC system. For the unsaturated zone, the gaseous sample in the site was directly applied to the TD-GC system. After verifying the accuracy and precision of the monitoring system, the continuous monitoring system was successfully operated for more than a month in the field. The monitoring system used in this study is applicable to other sites for continuous monitoring, thus providing a scientific background for advanced risk assessment and policy development.

Automatic temperature rise in the manure storage tank increases methane emissions: Worth to cool down!

A significant amount of CH4 is emitting from livestock manure (LM) storage tank, which is being counted according to the guidelines provided by the Intergovernmental Panel on Climate Change (IPCC). Among various parameters affecting CH4 conversion factor (MCF) of LM, temperature is known as the most influential factor. As a degree of temperature, atmospheric temperature (Ta), not the manure temperature (Tm), is used for determining the MCF. Currently, the closed-type tank is more common than open-type tank, which would cause the substantial difference between Ta and Tm, probably due to the automatic temperature rise (ATR). Here, we repeatedly observed the ATR by storing pig slurry (PS) in a pilot-scale tank (30 m3, surface/volume ratio of 1.9), and its consequent impact on the increased CH4 emissions by comparing with the results from a lab-scale tank (1 L, surface/volume ratio of 72.2) controlled at 30 °C. As storage began, the Tm increased gradually from 16 to 23 °C to above 30 °C even in winter (-5 °C < Ta < 15 °C). During 30 d of storage, the CH4 emissions of 1.3-2.5 kg CH4/ton PS (MCF 26-29%) was observed in the lab-scale tank, while the emissions was increased to 2.6-4.2 kg CH4/ton PS (MCF 40-50%) in the pilot-scale tank (Two-Tail test, |tt|<|tc|). For the first time, a detailed heat energy balance considering the waste heat from organic degradation, the heat requirement for warm up, and the heat loss by convection, was conducted, proving that the waste heat generated during storage was enough to reach above 30 °C. Cooling-down of LM at 20 °C was found to be effective for reducing CH4 emissions by 90%, which sufficiently offset the greenhouse gas emissions in power consumption for cooling. Our findings strongly suggest that more CH4 is emitting from LM storage tank than expected, and therefore, the IPCC needs to develop guidelines more accurately in determining MCF.

Electron bifurcation reactions in dark fermentation: An overview for better understanding and improvement.

Electron bifurcation (EB) is the most recently found mode of energy conservation, which involves both exergonic and endergonic electron transfer reactions to minimize energy loss. Several works have been devoted on EB reactions (EBRs) in anaerobic digestion but limited in dark fermentative hydrogen production (DF). Two main electron carriers in DF are ferredoxin (Fd) and reduced nicotinamide adenine dinucleotide (NADH), complicatedly involved in EB. Here, i) the importance of EB involvement in DF, ii) all EBRs possible to present in DF, as well as iii) the limitation of previous studies that tried incorporating any of EBRs in DF metabolic model, were highlighted. In addition, the concept of using metagenomic analysis for estimating the share of each EB reaction in the metabolic model, was proposed. This review is expected to initiate a new wave for studying EB, as a tool for explaining and predicting DF products.

Recent Advances Incorporating Superparamagnetic Nanoparticles into Immunoassays.

Superparamagnetic nanoparticles (SPMNPs) have attracted interest for various biomedical applications due to their unique magnetic behavior, excellent biocompatibility, easy surface modification, and low cost. Their unique magnetic properties, superparamagnetism, and magnetophoretic mobility have led to their inclusion in immunoassays to enhance biosensor sensitivity and allow for rapid detection of various analytes. In this review, we describe SPMNP characteristics valuable for incorporation into biosensors, including the use of SPMNPs to increase detection capabilities of surface plasmon resonance and giant magneto-resistive biosensors. The current status of SPMNP-based immunoassays to improve the sensitivity of rapid diagnostic tests is reviewed, and suggested strategies for the successful adoption of SPMNPs for immunoassays are presented.

Comprehensive understanding of nano-sized particle separation processes using nanoparticle tracking analysis.

The understanding of nano-sized particle separation processes has been limited by difficulties of nanoparticle characterization. In this study, nanoparticle tracking analysis (NTA) was deployed to evaluate the absolute particle size distributions in laboratory scale flocculation and filtration experiments with silver nanoparticles. The results from NTA were consistent with standard theories of particle destabilization and transport. Direct observations of changes in absolute particle size distributions from NTA enhance both qualitative and quantitative understanding of particle separation processes of nano-sized particles.

Isolation and characterization of fenobucarb-degrading bacteria from rice paddy soils.

Forty-five fenobucarb-degrading bacteria were isolated from rice paddy soils, and their genetic and phenotypic characteristics were investigated. The isolates were able to utilize fenobucarb as a sole source of carbon and energy. Analysis of the 16S rRNA gene sequence indicated that all the isolates were related to members of the genera Sphingobium and Novosphingobium. Among 45 isolates, 21 different chromosomal DNA fingerprinting patterns were obtained. All these strains exhibited similar growth and degradation patterns on fenobucarb. 2-sec-butylphenol was identified as an intermediate during fenobucarb degradation by HPLC analysis. All of the isolates were able to degrade another carbamate insecticide, carbaryl, and 2-sec-butylphenol, but not other fenobucarb related compounds such as aldicarb and fenoxycarb. Representative strains of the different repetitive extragenic palindromic sequence PCR fingerprint types had one to six plasmids. The plasmid-cured strains lost their degradation abilities, suggesting that fenobucarb degradative genes were on their plasmid DNAs in these strains. When analyzed with PCR amplification using the primers targeting for the previously reported carbamate hydrolase genes, most of the isolates did not exhibit any positive signals for different genes involved in carbamate degradation such as mcd, cahA and cehA genes. This is the first report that microorganisms involved in the degradation of fenobucarb have been isolated and the intermediate of fenobucarb biodegradation was identified.

Syntrophic biodegradation of butachlor by Mycobacterium sp. J7A and Sphingobium sp. J7B isolated from rice paddy soil.

Two bacterial strains involved in syntrophic degradation of chloroacetamide herbicide butachlor were isolated from a rice paddy soil. Analysis of 16S rRNA gene sequences indicated that the two isolates were related to members of the genera Mycobacterium and Sphingobium, respectively. Thus, a pair consisted of Mycobacterium sp. J7A and Sphingobium sp. J7B could rapidly degrade butachlor (100 mg L(-1)) at 28 °C within 24 h, while each isolate alone was not able to completely degrade butachlor. The isolate Mycobacterium sp. J7A was observed to grow slightly on butachlor, possibly utilizing the alkyl side chain of butachlor as its carbon and energy source, but the isolate Sphingobium sp. J7B alone could not grow on butachlor at all. Gas chromatography-mass spectrometry on catabolic intermediates revealed that the strain J7A produced and accumulated 2-chloro-N-(2,6-diethylphenyl) acetamide (CDEPA) during growth on butachlor. This intermediate was not further degraded by strain J7A, but strain J7B was observed to be able to completely degrade and grow on it through 2,6-diethylaniline (DEA). The results showed that butachlor was completely degraded by the two isolates by syntrophic metabolism, in which strain Mycobacterium sp. J7A degraded butachlor to CDEPA, which was subsequently degraded by strain Sphingobium sp. J7B through DEA.

Anaerobic lipid degradation through acidification and methanization.

In biological wastewater treatment high lipid concentration is known to inhibit microorganisms and cause active biomass flotation. To reduce lipid inhibition, a two-phase anaerobic system, consisting of an anaerobic sequencing batch reactor (ASBR) and an upflow anaerobic sludge blanket (UASB) reactor, was applied to synthetic dairy wastewater. During 153 days of operation, the two-phase system showed stable performance in lipid degradation. In the ASBR, a 13% lipid removal efficiency and 10% double bond removal efficiency were maintained. In the UASB, the chemical oxygen demand (COD), lipid and volatile fatty acid (VFA) removal efficiencies were more than 80%, 70% and 95%, respectively, up to organic loading rate 6.5 g COD/L/day. There were no operational problems such as serious scum formation or sludge washout. Protein degradation occurred prior to degradation during acidogenesis.