Nuclear Magnetic Resonance Technology Research Articles

Characterization of shear behavior and damage mechanism of periodic thermal loading sandstone based on NMR technique

We conducted research on the influence of periodic thermal loading on the shear behavior of sandstone through a series of direct shear tests with the aid of acoustic emission techniques. By capturing the evolution in pore structure with nuclear magnetic resonance technology and fractal theory to analyze the damage mechanism. The shear testing reveals that the periodic heating and air cooling sample exhibits a lower shear resistance compared to the continuous heating rock, with more pronounced differences observed in the water cooling samples. The peak shear strength and stiffness are greatly influenced by temperature and thermal loading methods, while the ultimate shear strength remains largely unaffected. Compared to samples with less severe damage, the acoustic emission macrocracking proportion of sandstone with more damage after thermal loading is more significant, corresponding to a smaller b-value. The study of the evolution in pore structure shows that mesopores and macropores exhibit favorable fractal characteristics distinct from micropores. The fractal dimension of mesopores and macropores are observed to be influenced by heating temperature and periodic thermal loading, as evidenced by their negative correlation with the thermal damage variable. After thermal loading, there was a negative correlation between porosity and fractal dimension in mesopores and macropores, indicating that the more severe the damage to the pore structure, the smaller the fractal dimension. The shear strength of periodic thermal loaded sandstone is closely related to the evolution of fractal dimension. The presence of thermal enhancement at 400 °C has been confirmed for the first time through fractal dimension analysis.

Insights into the effect of CNTs on cement hydration from the perspective of water evolution

The addition of carbon nanotubes (CNTs) into cement can remarkably enhance the mechanical properties of concrete. To investigate the impact of CNTs addition on the early-stage hydration of cement paste, low-field nuclear magnetic resonance (NMR) was employed to monitor the water evolution and microstructure of cement paste. The relaxation signals obtained from low-field NMR can provide valuable information regarding the state and content of water molecules, thereby indirectly characterizing the microstructural change of cement. Based on the correlation of characteristic transverse relaxation T 2 and water confinement state, low-field NMR can be used to predict the setting time of cement in the early stage. The findings indicated that the addition of CNTs can expedite the initial hydration process of cement, leading to a denser microstructure and shorter setting time. The results of Vicat needle test validated the efficacy of low-field NMR in predicting the setting time of cement. The non-destructive and non-invasive nature of low-field NMR technology renders it particularly advantageous in assessing the impact of CNTs on the early-stage behavior of cement paste.

Metabolomics study of the hepatoprotective effect of total flavonoids of Mallotus apelta leaf in carbon tetrachloride-induced liver fibrosis in rats.

Mallotus apelta leaf, recorded in the quality standard of Yao Medicinal Material in Guangxi Zhuang autonomous region, is commonly used in the treatment of liver diseases. Total flavonoids of M. apelta leaf (TFM) had good anti-fibrosis activity, but the anti-fibrosis mechanism of TFM is still unclear. Nuclear magnetic resonance technology was used to study the dynamic changes of urine metabolites in CCl4 -induced liver fibrosis before and after TFM treatment. Ingenuity Path Analysis (IPA) was used to find potential target genes for TFM to improve liver fibrosis and verify the expression of target genes by real-time fluorescent quantitative PCR and Western blotting. TFM can significantly reduce serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) levels, improve liver steatosis and reduce inflammation; in urine metabolomics, a total of seven potential biomarkers were found, mainly involving two metabolic pathways; IPA analysis showed that TNF may be a potential target for TFM to improve liver fibrosis induced by CCl4 in rats. This study found that TNF may be a potential target gene for TFM treatment of liver fibrosis, and shows that the anti-fibrosis mechanism of TFM could improve liver fibrosis by regulating the tricarboxylic acid cycle and subtaurine metabolism.

Perspectives on Novel Technologies of Processing and Monitoring the Safety and Quality of Prepared Food Products.

With the changes of lifestyles and rapid growth of prepared food industry, prepared fried rice that meets the consumption patterns of contemporary young people has become popular in China. Although prepared fried rice is convenient and nutritious, it has the following concerns in the supply chain: (1) susceptible to contamination by microorganisms; (2) rich in starch and prone to stall; and (3) vegetables in the ingredients have the issues of water loss and discoloration, and meat substances are vulnerable to oxidation and deterioration. As different ingredients are used in prepared fried rice, their food processing and quality monitoring techniques are also different. This paper reviews the key factors that cause changes in the quality of prepared fried rice, and the advantages and limitations of technologies in the processing and monitoring processes. The processing technologies for prepared fried rice include irradiation, high-voltage electric field, microwave, radio frequency, and ohmic heating, while the quality monitoring technologies include Raman spectral imaging, near-infrared spectral imaging, and low-field nuclear magnetic resonance technology. These technologies will serve as the foundation for enhancing the quality and safety of prepared fried rice and are essential to the further development of prepared fried rice in the emerging market.

The Characteristics of Fracturing Fluid Distribution after Fracturing and Shut-In Time Optimization in Unconventional Reservoirs Using NMR

Post-fracturing shut-in, as an important means of improving the energy efficiency of fracturing fluid, has been widely used in the development process of unconventional reservoirs. The determination of the shut-in duration is key to the effectiveness of shut-in measures. However, the distribution characteristics of the fracturing fluid during the post-fracturing shut-in period in unconventional reservoirs, such as the Chang 7 reservoir, were not clear, and the shut-in duration needed further optimization. Therefore, this paper employed low-field nuclear magnetic resonance (NMR) technology to study the distribution characteristics of the fracturing fluid during the post-fracturing shut-in period in unconventional reservoirs and optimized the shut-in duration. The study showed that the Chang 7 reservoir had a complex pore structure and relatively low porosity and permeability. During the shut-in process, the filtrate was distributed in pore throats with radii ranging from 0.0012 μm to 0.025 μm. Pore throats with radii ranging from 0.003 μm to 0.07 μm acted as dynamic pore throats in the process of imbibition displacement. When the shut-in duration for the Chang 7 segment was 7 days, the growth rate of the retained volume of fracturing fluid filtrate was the highest. When the shut-in duration was 10 days, there was no oil displacement in the medium and large pores, and the retained volume of filtrate was lower than that at 7 days shut-in, indicating that an optimal shut-in duration would be 7 days. This study can provide theoretical and technical support for the development of unconventional reservoirs.

Investigation of internal damage evolution in gneiss considering water softening

In soft rock tunnels, there are often large deformations during construction, especially when the groundwater seepage and softens the surrounding rock. For achieving the purpose of studying the softening effect of water immersion on strength and stability of surrounding rock, 15 rock samples were selected for physical and mechanical tests under 5 conditions: natural state and free immersion for 1, 3, 6, and 9 months, and nuclear magnetic resonance technology(NMR) was also adopted to test the internal pore structure of specimens with different immersion durations, thus the micro structure features of the gneiss, such as the NMR relaxation time T2 spectrum distribution, porosity, and pore volume ratio of different pore sizes under water softening were then obtained. The NMR results shows that the longer the free immersion duration of the rock sample, the greater the porosity; at the same time, the number of micropores in the rock gradually decreases under the interaction of water and rock, and the mesopores increase slightly first and then decrease all the time. The number of macropores is gradually increasing. When the immersion duration is 6 months, the number of macropores begins to increase significantly, and the mechanical properties of the specimens begin to drop significantly. By 9 months, the proportion of macropores in the rock has reached 57.6%. The results showed that the number growth of macropores is the root cause of the macroscopic failure of rock sample. The study results have significance for on-site construction in water-rich areas.

Discovery and validation of circulating stroke metabolites by NMR-based analyses using patients from the MISS and UK Biobank

BackgroundStroke is a significant health issue in the United States, and identifying biomarkers for the prevention and functional recovery after an acute stroke remains the highest priority. This study aims to identify circulating metabolite signatures that may be associated with stroke pathophysiology by performing discovery and validation studies. MethodsWe performed targeted metabolomics profiling of 420 participants of the discovery dataset of Metabolome in an Ischemic Stroke Study (MISS) using high-throughput nuclear magnetic resonance (NMR) spectroscopy. A validation study of significantly altered metabolites was conducted using an independent cohort of 117,988 participants from the UK Biobank, whose metabolomics profiles were generated using the same NMR technology. Results and conclusionOur study identified 16 metabolites to be significantly perturbed during acute stroke. Amino acid phenylalanine was significantly increased, while glutamine and histidine were significantly lowered in stroke. Serum levels of apolipoprotein A-1, HDL particles, small HDL particles, essential fatty acids, and phosphatidylcholine were reduced, while ketone bodies like 3-hydroxybutyrate and acetoacetate were markedly increased in stroke. Based on the robust validation in a large independent UK Biobank dataset, some of these analytes may become clinically meaningful biomarkers to predict or prevent stroke in humans.

Experimental study on damage law of liquid CO2 cyclic freeze–thaw coal

In order to study the damage characteristics of coal under liquid CO2 (LCO2) cyclic freeze-thaw (F-T), ultrasonic detector and infrared thermal imaging technology were used to discuss the ultrasonic wave propagation of coal and the surface temperature evolution law of coal samples during LCO2 cyclic F-T. The nuclear magnetic resonance technology was used to study the pore structure evolution of coal body. The results show that the velocity of primary wave and secondary wave is reduced. The more cycles, the lower the minimum temperature of coal side and end face. The temperature difference at different points on the same measuring line is large, indicates that the heterogeneity of coal sample under the same temperature causes anisotropy of heat transfer inside the matrix. The pore structure changes greatly under the LCO2 cyclic F–T action. With the increase of the number of cycles, the proportion of adsorption pores decreased, the proportion of seepage pores increased, and the pore volume increased，the total porosity and effective porosity showed an exponential upward trend, the bound porosity showed an exponential downward trend, indicating that LCO2 cyclic F–T is conducive to the increase of crack volume and the improvement of crack connectivity.

Nuclear magnetic resonance-based solvent system selection for counter-current chromatography separation of compounds present in the same high-performance liquid chromatography peak: Flavonoids in barley seedlings as an example.

Partition coefficient is a key parameter for counter-current chromatography separation. High-performance liquid chromatography (HPLC) is the most commonly used tool for the screening of partition coefficients. However, HPLC technology is not applicable to the compounds present in the same chromatographic peak. Nuclear magnetic resonance (NMR) technology could easily distinguish compounds according to their characteristic absorption even if they exist in the same HPLC peak. In this study, two flavonoids present in the same HPLC peak were successfully purified by counter-current chromatography with a solvent system screened by NMR to show the great potential of NMR technology in the screening of the partition coefficient of co-efflux compounds. Through NMR screening, an optimized ethyl acetate/n-buthanol/water (7:3:10, v/v/v) system was applied in this study. As a result, two flavonoids, including 4.8mg of 3'-methoxyl-6'''-O-feruloylsaponarin and 9.8mg of 6'''-O-feruloylsaponarin were separated from 15mg of the mixture. There is only one methoxy group difference between the two flavonoids. This study provides a new strategy for the screening of counter-current chromatography solvent systems and broadens the application scope of counter-current chromatography.

Study on water seepage law of confined coal body and optimization of water injection parameters

To optimize water injection parameters, it is necessary to understand the water seepage characteristics of coal and establish an evaluation method for the coal seam water injection effect. Using low-field nuclear magnetic resonance (NMR) technology and a peripheral loading pressure experimental system, real-time Carr-Purcell-Meiboom-Gill sequence tests were conducted on coal samples under different water injection schemes. The dynamic migration characteristics of pressurized water in coal under a constant water injection pressure and injection flow were studied. The results showed that under a fixed water injection pressure, the change in water content with injection time was in concordance with first-order kinetics, indicating that the process is controlled by diffusion. Combined with the fitting results of the wetting rate constant and water injection pressure, the best water injection pressure was obtained. Moderate water injection flow, an increase in water injection volume, and an extension of the water injection time can improve the wetting effect. Under constant water pressure, water seepage in the coal includes two processes: the rapid migration of free water to the pore fractures of coal and the spontaneous water absorption process in the coal. Under constant water flow, the water seepage process in the coal is consistent with the Boltzmann equation. Based on the time constant and inflection point of the time growth obtained by the Boltzmann equation, the seepage process was divided into the water inflow, water transportation, and water adsorption stages. The peak area of the adsorbed water is proportional to the mass of coal moisture. This relationship can realize the mutual conversion between the NMR water signal quantity and moisture content in coal.

Laboratory tests and field pilot of foam-assisted deoxidized-air flooding in a low-permeability sandstone reservoir

Foam-assisted deoxidized-air flooding is a promising technique for improving oil recovery, particularly in low-permeability oil reservoirs. However, significant differences in displacement efficiency have been observed. A comprehensive program including field pilot analysis in Wuliwan oil reservoir, a low-permeability reservoir in China, and laboratory experiments was initiated to investigate the displacement mechanism of foam-assisted deoxidized-air flooding. We carried out a series of laboratory experiments of foam-assisted deoxidized-air flooding with different gas–liquid ratios at different water cut stages, while using nuclear magnetic resonance technology to monitor the distribution of crude oil in pores. The results revealed that increasing gas–liquid ratio enhanced oil recovery during the high water cut stage, but reduced it during the middle water cut stage. The differences in oil recovery at different water cut stage appear to be linked to changes of the displacement mechanism. We indeed observed that oil was produced from a wide range of pores at the high water cut stage, but only from the macropores at the middle water cut stage. The field pilot analysis supported our conclusion based on the experimental findings, that foam-assisted deoxidized-air flooding using an appropriate gas–liquid ratio can efficiently lower water cut and enhance oil production at different water cut stages. The combination of laboratory and field pilot tests used here can serve as a template for future studies in other oil reserves.

Exploring the Unique Characteristics of High-Pore-Volume Waterflooding and Enhanced Oil Recovery Mechanisms in Offshore Sandstone Reservoirs Using Nuclear Magnetic Resonance Technology

A single paragraph of about 200 words maximum. For research articles, abstracts should give a pertinent overview of the work. We strongly encourage authors to use the following style of structured abstracts, but without headings: (1) Background: Place the question addressed in a broad context and highlight the purpose of the study; (2) Methods: briefly describe the main methods or treatments applied; (3) Results: summarize the article’s main findings; (4) Conclusions: indicate the main conclusions or interpretations. The abstract should be an objective representation of the article and it must not contain results that are not presented and substantiated in the main text and should not exaggerate the main conclusions.

Application of Multifractal Theory for Determination of Fluid Movability of Coal-Measure Sedimentary Rocks Using Nuclear Magnetic Resonance (NMR)

A precise evaluation of the fluid movability of coal sedimentary rock is crucial to the effective and secure utilization of coal measures gas reserves. Furthermore, its complex pore structure and diverse mineral components impact the flow properties of fluids in pore structures, causing accurate evaluation of fluid mobility to be extremely challenging. Nuclear magnetic resonance (NMR) technology is currently a prevalent technique to assess unconventional reservoirs due to its capacity to acquire abundant reservoir physical property data and determine fluid details. The free-fluid volume index (FFI) is a crucial factor in assessing fluid movability in the application of NMR technology, which can only be derived through intricate NMR saturation and centrifugation experiments This research utilized nuclear magnetic resonance (NMR) tests on 13 classic coal-measure sedimentary rock samples of three lithologies to reveal the FFI value. Moreover, the association between mineral components, pore structure parameters, and FFI was then extensively analyzed, and a prediction model for FFI was constructed. The results indicate that the T2 spectra of sandstone and shale own a bimodal distribution, with the principal point between 0.1 and 10 ms and the secondary peak between 10 and 100 ms. The majority of the T2 spectra of mudstone samples provide a unimodal distribution, with the main peak distribution range spanning between 0.1 and 10 ms, demonstrating that the most of the experimental samples are micropores and transition pores. The calculated results of the FFI range from 7.65% to 18.36%, and depict evident multifractal properties. Porosity, the content of kaolinite, multifractal dimension (Dq), and the FFI are linearly positively correlated. In contrast, the content of chlorite, illite, multifractal dimension subtraction (Dmin − Dmax), multifractal dimension proportion (Dmin/Dmax), and singularity strength (Δα) possess a negative linear correlation with the FFI, which can be further used for modeling. On the basis of the aforementioned influencing factors and the FFI experimental values of eight core samples, an FFI prediction model was constructed through multiple linear regression analysis. The accuracy of the prediction model was validated by utilizing this approach to five samples not included in the model development. It was revealed that the prediction model produced accurate predictions, and the research findings may serve as a guide for the classification and estimation of fluid types in coal reservoirs.

Characterizing moisture occurrence state in coal gasification fine slag filter cake using low field nuclear magnetic resonance technology

ABSTRACT Gasification fine slag, a carbon-rich solid waste produced during coal gasification, is currently disposed of through conventional landfilling methods. Its high-water content hampers resource utilization by reducing its calorific value. This study employs low field nuclear magnetic resonance (LF-NMR) analysis to investigate the water occurrence states in a filter cake with 70.7% moisture content derived from fine gasification slag of the Ningxia coal water slurry furnace. The analysis reveals that free water constitutes a major proportion (68.28%), while combined and capillary water accounts for 2.62% and 2.33%, respectively. The removal of moisture from the coal gasification fine slag filter cake is significantly affected by the drying temperature. The drying rate initially increases and then decreases with different temperatures. For drying temperatures of 60, 70, 80, 90, and 100°C, the maximum drying rates are achieved at 1.09, 1.23, 2.18, 3.86, and 4.01%/min, respectively, with corresponding durations of 40, 40, 25, 30, and 35 min. The T22 relaxation peak area continually decreases and shifts leftward on the coordinate axis. The behavior of the T23 and T22 peaks follows a similar pattern, indicating that water with higher mobility is easily eliminated during drying, while the T21 peak exhibits a robust signal strength throughout the drying process. At a drying temperature of 100°C, the proportion of free water (A22) decreases from 87.3% to 0, the A23 fluctuates between 0 and 5.3%, and the bound water peak area (A21) increases from 10.4% to 94.7% as drying time prolongs. A relationship model is developed between the moisture content of the coal gasification fine slag filter cake and the total integral area of the LF-NMR test, enabling rapid detection and analysis of the total moisture content and distinct occurrence states in the filter cake.

Evolution Characteristics of Coal Microstructure before and after Supercritical CO2 Treatment Based on the L-Weighing-LNMR Method

To accurately and quantitatively characterize the evolution of coal microstructures before and after supercritical CO2 treatment, this paper proposes a microstructural analysis for coal-rock based on low-field nuclear magnetic resonance (LNMR) technology, the L-weighing method. The experimental results of the L-weighing method and the LNMR method were compared and analyzed. The results showed that there were differences between the experimental results of the L-weighing method and the LNMR method, but the overall laws were basically the same. The L-weighing method quantitatively characterizes the water content in coal and determines water consumption and microscopic component extraction in coal with supercritical CO2, while the LNMR method only determines the dissolution of H-containing substances in the coal by supercritical CO2. According to the combined analysis with the L-weighing method and the LNMR method, after the supercritical CO2 entered the coal, it consumed 0.33 g of water from the coal and extracted 0.32 g of microscopic components from the coal, reacted chemically with both water and microscopic components in the coal, and provided effective water consumption and extraction of the coal. The supercritical CO2 increased the saturable water in the coal by 0.71 g, the porosity by 1.57%, and the pore seepage volume by a factor of 1.10, which expanded the volume and increased the permeability of the coal. After the reaction with supercritical CO2, the centrifugal water loss of the coal increased by 0.16 g, the T2 cutoff (T2C) of the coal had shifted to the left by 0.31 ms, and the free water volume of the coal had increased by a factor of 1.15, which enhanced the pore connectivity in the coal. The water consumption, extraction, volume expansion, permeability increase, and pore connectivity increase were primarily responsible for the changes in the coal microstructure effected by supercritical CO2.

Probing the kinetics of chemical reactions in ultra-small droplet samples using digital microfluidic nuclear magnetic resonance spectroscopy

In this study, we present a digital microfluidic (DMF) system that connects analyte droplets with planar microcoils in a high-field nuclear magnetic resonance (NMR) spectrometer for in situ photoreaction analysis. Transparent indium tin oxide glass was employed in fabricating the DMF electrode chips. NMR spectroscopy was utilized for its superior sensitivity and ability to detect small changes in molecular structure, making it highly advantageous for chemical analysis. Utilizing Computer Simulation Technology Studio Suite, we designed a plane annular microstrip coil that accurately matches droplet shape to optimize detection sensitivity and increase filling factor. An advanced DMF control circuit remotely manages droplet samples and facilitates precise mixing for in situ reaction analysis. Our results demonstrate improved sensitivity in the in situ experimental analysis, such as the aldehyde amine reaction (sodium benzaldehyde-2-sulfonate solution and aniline solution) and photopolymerization reaction (polyethylene glycol ester). The integration of DMF and NMR technologies provides a promising approach for increasing efficiency and accuracy in chemical analysis.

Solvent extraction of superfine pulverized Coal. Part 4. Carbon skeleton characteristics

To better understand the molecular structure of superfine pulverized coal and promote its practical utilization, the NMR (nuclear magnetic resonance) technology is adopted to study the structural information of all the products from the solvent extraction process, including raw coal, residue, and extract. The whole set of NMR spectra is resolved into different individual curves with specific linewidths, shapes, and intensities. According to the chemical shift, the carbon skeleton characteristics like the aromaticity, cluster size, and other structural lattice parameters are analyzed in detail. More importantly, the influences of coal maturity, coal size, and solvent on the carbon structural evolution during the extraction process are focused on. The results show that the aromatic ring stacking and aromatic ring exposure and fragmentation occur competitively during the superfine comminution, promoting the structural evolution of the coal. In addition, aliphatic carbon transfers more from raw coal into the extract than aromatic carbon in the whole extraction process, which is accompanied by the disappearance of carbonyl groups. Furthermore, the reduction of particle size can promote the extraction effect of the extractant on the coal powder, and reduce the proportion of aliphatic carbon in the residue. The work introduces the correlations among the raw coal, residue and extract from a carbon skeleton point of view, providing a reference for elucidating the solvent extraction mechanisms. The results shed light on better understanding the coal structure and its further molecular modeling.

Effect of Fines Content on Pore Distribution of Sand/Clay Composite Soil

Plant sand fixation is the most durable and environmentally friendly sand mitigation measure for windblown sand hazards. For aeolian–sand composite soil, the fines content is the main factor affecting the pore size distribution characteristics and determines the soil water retention characteristics. Sandy soil with uniform particle size was used as the material, low-plasticity clay as a fine particle, and composite soils with different fines content were prepared. The evolution of the pore size distribution of composite soils was quantitatively determined using low-field nuclear magnetic resonance technology, and the influence of the fines content on the pore size distribution was obtained. The results show that as the fines content increases, the pore size first increases and then decreases. The pore size distribution curve gradually changes from a single-peak structure to a double-peak structure and becomes a unimodal structure again. The corresponding dominant pore size of composite soils increases first and then decreases with the increase in the fines content. A critical fine particle content is identified to control the strong local honeycomb pore structure of composite soils, which provides a theoretical basis for the material selection and design of plant sand fixation measures.

Characterization of Shale Porosity and Permeability by Nuclear Magnetic Resonance

To rapidly evaluate and characterize the porosity and permeability of shale reservoirs, this study uses Nuclear Magnetic Resonance (NMR) technology to classify the T2 spectrums of different shale reservoirs, analyzes the correlation between the T2 cut-off values and the main peaks of the T2 spectrums of the shale reservoirs, and establishes a rapid identification and evaluation method for different fluid signals of the reservoirs. Also, the correlation between the area of signals and shale permeability in different signal intervals is explored, and finally, a rapid evaluation method of shale pore structure characteristics based on NMR technology is developed. This study can provide methodological guidance and theoretical support for the rapid characterization of the porosity and permeability of shale reservoirs based on NMR technology.

Immobilization of Thai Population-specific Human Leukocyte Antigens on Magnetic Nanoparticles Integrated with Nuclear Magnetic Resonance Technology

Kidney disease, as a global health problem, can progress to kidney failure. Kidney transplantation is a treatment option for end-stage disease and an alternative to dialysis. Complement-dependent cytotoxicity tests and flow cytometry are methods used to test for compatibility between autoantibodies and donor recipient. Antibodies against donor human leukocyte antigens (HLAs), linked to hyperacute or severely acute rejection, frequently result in graft loss. Currently, fluorescent bead assay (Luminex^®) technology is used in Thailand for HLA–antibody typing tests. However, each test requires specific location and time, expensive equipment, and high costs. The goal of such research is that, HLA–antibody typing tests can be performed wherever it is the most convenient for recipients and hospitals. A further advantage is that the surgeon can perform a final test for confirmation before the surgery. Numerous technologies are currently available for this purpose. The focus of this study was on the Fe₃O₄ magnetic nanoparticles (MNPs) immobilized with HLAs frequently found in the Thai population. These were examined using nuclear magnetic resonance (NMR) to measure HLA antibody typing. MNPs have recently attracted considerable attention because of their strong magnetization and large surface areas. Immobilization reactions with antigens and the straightforward magnetic separation of MNPs are low-cost techniques. Hence, the commercialization of Fe₃O₄ MNPs is favorable. In this study, MNPs were functionalized with 3-aminopropyl triethoxysilane (APTES) in toluene and ethanol, and the nanoparticles were streptavidin activated after APTES treatment. A specific biotinylated HLA for the Thai population was used and immobilized on streptavidin. The MNPs were effectively immobilized. The magnetic properties can be modified by adding other ions to Fe₃O₄. We discovered that the shape and size variations of Fe₃O₄ MNPs may have an impact on the amount of functionalized and immobilized surface area.