Solid Phase Research Articles

Unlocking the solution-phase molecular transformation of biochar during intensive rainfall events: Implications for the long-term carbon cycle under climate change

The unclear turnover of soluble and solid phases of biochar during increasingly severe climate change (e.g., intensive rainfall) raised questions about the carbon stability of biochar in soil. Here, we present an in-depth analysis of the molecular-level transformations occurring in both the soluble and solid phases of biochar subjected to prolonged wet-dry cycles with simulated rainwater. Biochar properties, including surface functionality and carbon texture, greatly affected the transformation route and led to a distinct stability variation. The rich alkyl −CH3 on the low-temperature biochar (450 °C) was oxidized to hydroxymethyl −CH2OH or formyl −CHO, and the ester −COOC− or peptide −CONHC− bonds were fragmented in the meantime, causing the release of protein- or lipid-like organic carbon and the declined carbon stability (Æ, tested by H2O2 oxidation, from 60.1% to 53.2%). After a high-temperature (750 °C) pyrolysis process, only oxidation of the surface −OH with limited bond breaking occurred after rainwater elution, presenting a marginal composition difference with constant stability. However, the fragile carbon nature of biochar, caused by CO2 activation, led to enhanced fragmentation, oxidation, and hydration, resulting in the release of tannin-like organic carbon, which compromised the carbon storage (Æ decreased from 81.2% to 73.0%). Our findings evaluated the critical transformation of biochar during intensive rainfall, offering crucial insights for designing sustainable biochar and achieving carbon neutrality.

Chemically Stable Diazo Peptides as Selective Probes of Cysteine Proteases in Living Cells

Diazo peptides have been described earlier, however, due to their high reactivity have not been broadly used until today. Here, we report the preparation, properties, and applications of chemically stable internal diazo peptides. Peptidyl phosphoranylidene‐esters and amides were found to react with triflyl azide primarily to novel 3,4‐disubstituted triazolyl‐peptides. Nonaflyl azide instead furnished diazo peptides, which are chemically stable from pH 1‐14 as amides and from pH 1‐8 as esters. Thus, diazo peptides prepared by solid phase peptide synthesis were stable to final deprotection with 95% trifluoroacetic acid. Diazo peptides with the recognition sequence of caspase‐3 were identified as specific, covalent, and irreversible inhibitors of this enzyme at low nanomolar concentrations. A fluorescent diazo peptide entered living cells enabling microscopic imaging and quantification of apoptotic cells via flow cytometry. Thus, internal diazo peptides constitute a novel class of activity‐based probes and enzyme inhibitors useful in chemical biology and medicinal chemistry.

Chemically Stable Diazo Peptides as Selective Probes of Cysteine Proteases in Living Cells.

Diazo peptides have been described earlier, however, due to their high reactivity have not been broadly used until today. Here, we report the preparation, properties, and applications of chemically stable internal diazo peptides. Peptidyl phosphoranylidene-esters and amides were found to react with triflyl azide primarily to novel 3,4-disubstituted triazolyl-peptides. Nonaflyl azide instead furnished diazo peptides, which are chemically stable from pH 1-14 as amides and from pH 1-8 as esters. Thus, diazo peptides prepared by solid phase peptide synthesis were stable to final deprotection with 95% trifluoroacetic acid. Diazo peptides with the recognition sequence of caspase-3 were identified as specific, covalent, and irreversible inhibitors of this enzyme at low nanomolar concentrations. A fluorescent diazo peptide entered living cells enabling microscopic imaging and quantification of apoptotic cells via flow cytometry. Thus, internal diazo peptides constitute a novel class of activity-based probes and enzyme inhibitors useful in chemical biology and medicinal chemistry.

Advancing greener LNG-fueled vessels: Compact simultaneous reduction system for CH4, NOX and CO2 emissions

Stringent ship regulations necessitate simultaneous emission reductions, challenged by cargo loss and energy constraints. This study proposes a compact reduction system that simultaneously mitigate CH4, NOX, and CO2 emissions onboard LNG-fueled vessels. The proposed system integrates two pivotal technologies: a metal support-based compact methane oxidation catalyst (MOC)-selective catalytic reduction (SCR) system to capture CH4 and NOX, and a cryogenic CO2 capture (CCC) system to capture and store CO2 in its solid phase utilizing LNG's cold energy. This innovative approach addresses two challenges. First, the compact MOC-SCR system employs metal support with an enhanced surface area-to-volume ratio surpassing the capabilities of ceramic support materials, achieving a volume reduction of 80.02% and 79.82% respectively. Secondly, the CCC system significantly lowers specific energy consumption by 61.54% by harnessing LNG's cold energy compared to the absorption-based CO2 capture system. As a result, the proposed system not only reduces CH4, NOX, and CO2 emissions simultaneously with a high capture rate but also reduces volume and weight. Furthermore, it achieves a high CO2 capture rate of 92.12%, while diminishing cargo losses by 25.30%. These findings provide valuable guidance for developing environmentally sustainable vessels, aligning with the continuously increasing stringency of regulations.

Cellular automaton simulation of solid-phase grain growth under conditions involving scanning heat sources and temperature gradients

Abstract A cellular automaton simulation of grain growth in a solid phase was conducted, considering the temperature gradient, heat source movement, and conditions favoring prioritized grain growth. The results reveal that, under optimal conditions, cellular grains elongated in the direction of the heat source movement. Detailed simulations illustrate the dynamics of grain growth and effect of mobility and driving forces on the dynamics, providing valuable insights into cellular grain growth in a solid phase.

Experimental investigation of CO2 capture at high pressure using energy-efficient amino acid salt solvents

The increase in energy consumption has led to greenhouse gas emissions, specifically CO2. This has caused many researchers to explore the possibility of capturing CO2 emissions. The utilization of typical water-based solvents, such as amine solutions, poses challenges in large-scale operations owing to the substantial energy consumption associated with their regeneration process. To decrease the energy required to regenerate the solvent, new types of phase change solvents, known as lean water amino acid-based phase change solvents, were invented. This study investigated the absorption capacity of an amino acid salt made up of glutamine and potassium hydroxide in a water-based solution including N,N-dimethylformamide (DMF) as a co-solvent. The measurement of absorption capacity was conducted under elevated pressures ranging from 5 to 30 bar. Additionally, an investigation was conducted to assess the impact of DMF volumetric concentration on absorption capacity. The findings of the study indicated that augmenting both the pressure and concentration of DMF increased the capacity for CO2 absorption. This enhancement was achieved by simultaneously raising the rates of physical and chemical absorption. The results obtained from the C NMR phase analysis revealed that the solid phase had carbon bonds that were related to the absorption of CO2, whilst the upper liquid phase did not contain any CO2. This phase might readily be recycled into the absorption process without the need for regeneration. The absorption capacity of this solvent was also assessed following three absorption-reduction cycles. The results indicated a decrease in absorption capacity by only 6.6 %.

Efficient mapping of phase diagrams with conditional Boltzmann Generators

Abstract The accurate prediction of phase diagrams is of central importance for both the fundamental understanding of materials as well as for technological applications in material sciences. However, the computational prediction of the relative stability between phases based on their free energy is a daunting task, as traditional free energy estimators require a large amount of simulation data to obtain uncorrelated equilibrium samples over a grid of thermodynamic states. In this work, we develop deep generative machine learning models based on the Boltzmann Generator approach for entire phase diagrams, employing normalizing flows conditioned on the thermodynamic states, e.g., temperature and pressure, that they map to. By training a single normalizing flow to transform the equilibrium distribution sampled at only one reference thermodynamic state to a wide range of target temperatures and pressures, we can efficiently generate equilibrium samples across the entire phase diagram. Using a permutation-equivariant architecture allows us, thereby, to treat solid and liquid phases on the same footing. We demonstrate our approach by predicting the solid-liquid coexistence line for a Lennard-Jones system in excellent agreement with state-of-the-art free energy methods while significantly reducing the number of energy evaluations needed.

Geochemical Interaction and Bioavailability of Zinc in Soil Under Long‐Term Integrated Nutrient Management in Pearl Millet–Wheat System

ABSTRACTThe degree and severity of zinc (Zn) deficiency in soil reduced the agricultural yield and quality, thus encouraging malnutrition in humans worldwide. The study was hypothesized to increase the bioavailability and release of Zn in soil and Zn biofortification in wheat grains under integrated nutrient management (INM). The long‐term (54 years) experiment laid out in a split‐plot design comprising single (W) and dual (PW) applications of farmyard manure (FYM) (0, 5, 10, and 15 Mg ha−1) and nitrogen (0, 60, and 120 kg ha−1) was studied to understand the distribution of different Zn fractions in soil and their relationship to wheat grain yield and Zn uptake. A laboratory incubation study was performed on surface soils to evaluate the release kinetics of native Zn at field capacity. The different fractions of Zn in soil increased with increasing frequency and levels of FYM application. Residual Zn constituted the maximum proportion (89.03%) of total soil Zn. A high positive correlation (p < 0.01) of diethylenetriaminepentaacetic acid (DTPA)‐extractable Zn and total grain Zn content were observed with different Zn fractions. The release kinetics of native soil Zn increased up to 10 days and became almost constant, indicating the establishment of chemical equilibria between the soil solid and solution phase. Thus, long‐term INM ensured higher wheat production (6.08 Mg ha−1) and Zn biofortification (38.95 mg kg−1) to combat Zn malnutrition and achieve the United Nations’ sustainable development goals on “zero hunger” and “good health and well‐being.”

Pre‐oxidized Recycled MgO–Steel Composite Material for Possible Application in Cryolitic Melts

Recycled MgO–C lining bricks and 316L stainless steel are used to manufacture composite material for inert anode samples for aluminum electrolysis cell. The microstructure of the composite material is characterized after preoxidation thermal treatments at 800, 900, and 1000 °C as well as in its sintered state. Preoxidation (PO) process is designed to enhance the material's corrosion resistance in molten cryolite environments by developing robust Fe–Mg–O, Fe–Cr–O‐ containing phases. Analytical techniques including scanning electron microscopy, electron backscatter diffraction, and energy dispersive X‐ray spectrometry are applied to characterize the phase formation, revealing the potential of these composites for use as inert anodes in aluminum electrolysis cells. PO at 800 °C is not sufficient to form adequate protective oxide layers. Whereas, PO at 900 and 1000 °C leads to the formation of protective oxide layers containing Mg–O Fe–O halite‐like solid solutions and (Cr,Fe)3O4 spinel phase. Sample, preoxidized at 1000 °C is sealed in Mg–Fe–O spinel phase.

Effect of plasma nitriding on microstructure and wear behavior of electrodeposited FeCoNiCr coating

An (FeCoNiCr)N high-entropy alloy coating with a single FCC phase was fabricated on 304 stainless steel by electrodeposition and plasma nitriding. The results indicated that the FeCoNiCr coating exhibited typical granular morphologies and a nearly equiatomic ratio of four elemental compositions. After nitriding, the coating primarily consisted of a high-entropy solid solution phase and a CrN phase, with the microstructure of the (FeCoNiCr)N coating being significantly refined due to the effect of crystallization. The microhardness of the (FeCoNiCr)N coating was 781.30 ± 20.3 HV0.5, considerably higher than that of the FeCoNiCr coating, which was 496.48 ± 21.82 HV0.5. Additionally, the (FeCoNiCr)N coating demonstrated a low friction coefficient and a wear rate of 0.59 and 6.8 × 10−8 mm3/N mm, respectively. The fine microstructure and high resistance to plastic deformation, attributed to solid solution strengthening and dispersion strengthening, were the primary factors contributing to the excellent wear performance of the (FeCoNiCr)N coating.

A Semi‐Analytical Method for Simulating Near‐Field Antiplane Wave Propagation in Layered Fluid‐Saturated Porous Media

ABSTRACTA semi‐analytical method for the near‐field antiplane wave propagation analysis in the layered fluid‐saturated porous media (FSPM) is proposed based on the Biot u–U dynamic formulation. The wave propagation equations of the FSPM are decoupled by the variable‐separating method. The thin‐layer element method (TLEM) is applied to discretize the infinite domain and construct the consistent artificial boundary condition. The finite element method (FEM) is adopted for the space discretization of the finite domain and the numerical solution of the dynamic response. The proposed method is validated by the comparison of the numerical results of this method with those in the published references and acquired from the remote artificial boundary. Subsequently, this method is applied to investigate typical near‐field antiplane wave propagation problems in the FSPM. Parametric sensitivity investigations are also executed to explore the impact of mechanical parameters, including permeability coefficients, porosity, and shear modulus of the solid phase, on the dynamic response of the FSPM. The study results confirm the efficacy and efficiency of the proposed method in the near‐field antiplane wave propagation analysis in the FSPM.

Impact of Adsorption on the Vapor Availability of Contained Explosives and Drugs

AbstractDetection canines are used to locate explosives, drugs, and other contraband based on the presence of volatile organic compounds (VOCs) associated with the target items, even when attempts have been made to contain them in layers of packaging. It is important to understand the extent to which different materials impact vapor availability through adsorption or absorption and therefore the ability of canines to detect target materials. This study considered how the attenuation of vapor components associated with explosives and drugs (hexamethylene triperoxide diamine (HMTD), trinitrotoluene (TNT), triacetone triperoxide (TATP), and cocaine) by commonly used concealment and storage materials (metal, glass, plastic, and cardboard). Adsorption/desorption affinity was measured using a quartz crystal microbalance which can measure nanogram level mass changes as vapor from an analyte is flowed over and interacts with a sensor coated in a material of interest. Headspace analysis using solid phase microextraction (SPME) with gas chromatography/mass spectrometry or electron capture detector (GC/MS or ECD) measured the VOCs over time as each analyte of interest was exposed to either 50 cm2 or 100 cm2 of each material. Overall, the results demonstrated that the amount of sorption and vapor suppression varies based on the material, with the greatest attenuation of analyte vapor by cardboard, followed by polystyrene, and then glass. Furthermore, it also depends on the analyte, as demonstrated by minimal sorption of TATP, particularly to polystyrene, and the compounds in HMTD having different affinities resulting in an altered vapor profile.

Anomalous release of indoles from amorphous solid dispersion formed with a polymeric network

AbstractAmorphous solid dispersion (ASDs) is a technique used in the pharmaceutical industry to enhance the solubility, dissolution rate, and bioavailability of poorly soluble drugs. Polymeric materials, and recently polymer gels form and stabilize the amorphous structure by inhibiting the aggregation/precipitation of such drugs. In this work indole, 5-aminoindole and 5-hydroxyindole loaded poly (N-isopropylacrylamide) (PNIPA) hydrogels were studied. Swelling and uptake measurements, X-ray diffraction (XRD), liquid and solid phase nuclear magnetic spectroscopy (NMR) and high sensitivity differential scanning calorimetry (DSC) were applied to understand the drug – matrix interactions affecting the release. We confirmed that the hydrogel fostered the fine uniform distribution of the hydrophobic probe molecules and successfully prevented any crystalline or amorphous phase formation during water removal, leading to a glassy solution, a special form of ASD. Despite the limited difference between their chemical composition the probe molecules showed dissimilar drug release behavior from dried loaded gel disks. While Nuclear Overhauser Enhancement Spectroscopy (NOESY) measurements revealed a “bidental” interaction between 5-hydroxiindole and the polymer, no localized interactions were found for indole. The release of the bidentally linked derivatives is rapid and complete: they act as molecular spacers, promoting the rehydration of the chains. In contrast, part of the indole remains irreversibly trapped being confined between the chains without any orientation, shedding light on the role of the steric consequences of the interaction. Our findings also indicate that such drug delivery compositions should be treated as ternary systems (carrier + drug + liquid) already in the design stages of drug release systems.

Performance analysis of a molten salt packed-bed thermal energy storage system using three different waste materials

Concentrated Solar Power (CSP) is a critical technology for the renewable energy transition, offering high power output at elevated temperatures. However, further integration of CSP plants requires a reduction in investment costs. This study investigates the use of cost-effective, sustainable, waste-based TES materials—such as Electric Arc Furnace Black Slag (BS) and Tundish (TN) from the steel industry, as well as Demolition Waste (DW) from urban regeneration projects—as packing materials in TES systems to reduce the capital expenditure of CSP plants. A One-Dimensional Continuous Solid Phase (1D-2P) model was employed to evaluate and compare the performance of DW, TN, and BS. The results revealed that all materials demonstrated comparable properties, with TN exhibiting the highest energy storage capacity (44.7 kWh) and energy storage density (296 kWh/m³). With high utilization rates of 73–75 %, waste-based TES systems show strong potential for application in CSP plants. The TES systems were scaled for a 110 MW CSP plant, which currently operates with a 2-tank molten salt TES system providing 4648.4 MWh of storage capacity. TN required the smallest storage volume of 22,273 m³ for the 110 MW CSP plant. The reduction of molten salt usage by up to 31,000 tons in the waste-based packed-bed TES system could significantly enhance the economic feasibility of CSP plants.

Occurrence Characteristics and Health Risk Assessment of Organophosphate Esters in Tap Water of Shanghai

To explore the occurrence characteristics and health risk levels of the new pollutants organophosphate esters （OPEs） in tap water in Shanghai, based on the water supply areas of the Qingcaosha Reservoir, Chenhang Reservoir, Dongfeng Xisha Reservoir, and Upstream Huangpu River water sources, a total of 52 large shopping malls in Shanghai were selected as tap water sampling sites. Solid phase extraction and gas chromatography-triple quadrupole mass spectrometry were used to determine eight types of OPEs in tap water from shopping malls, including three types of chlorinated OPEs, two types of alkyl OPEs, and three types of aryl OPEs. On this basis, the health risk assessment of the substances with high detection frequency and concentration was carried out. The results showed that six types of OPEs were generally detected, and the average levels of eight types of OPEs in tap water collected in summer and winter were 64.3 ng·L-1 and 60.5 ng·L-1, respectively. The concentration levels and detection rates of different types of OPEs in tap water followed the order of： chlorinated OPEs > alkyl OPEs > aryl OPEs. From the perspective of water sources, the average concentration of OPEs in tap water with Upstream Huangpu River water sources as the water source was the highest （132 ng·L-1 in summer and 170 ng·L-1 in winter）, and OPEs in tap water with Dongfeng Xisha Reservoir as the water source was the lowest （25.1 ng·L-1 in summer and 6.62 ng·L-1 in winter）. The average concentration of chlorinated OPEs in summer （62.1 ng·L-1） was higher than that in winter （53.9 ng·L-1）. Based on the reference dose of OPEs, there were no health risks to people of all ages through drinking water exposure. However, the OPE exposure in tap water of Shanghai was higher compared with that of other countries and regions, which requires further attention and research.

Exact analytical solution of the equations for a quasiequilibrium two-phase domain: permeability and interdendritic spacing

This study is concerned with the theoretical description of a quasi-stationary process of directional crystallization of binary melts and solutions in the presence of a quasi-equilibrium two-phase region. The quasi-equilibrium process is ensured by the fact that the system supercooling is almost completely compensated by heat released during the phase transformation. Quasi-stationarity of the process determining constancy of the crystallization rate is ensured by given temperature gradients in the solid and liquid phases. The system of heat and mass transfer equations and boundary conditions to them under these assumptions is dependent on a single spatial variable in the reference frame moving with the crystallization rate relative to a laboratory coordinate system. Exact analytical solutions to the formulated problem in parametric form are obtained. The parameter of the solution is the solid phase fraction in a two-phase region. The distributions of temperature and impurity concentration in the solid, liquid and two-phase regions of the crystallizing system, the rate of solidification, and the spatial coordinate in the two-phase region depending on the solid phase fraction in it are found. An algebraic equation for the solid phase fraction at the interface between the solid material and the two-phase region is derived. Exact analytical solutions show that the impurity concentration in the two-phase layer increases as the solid phase fraction increases. Moreover, the solid phase fraction at the interface solid phase — two phase region and its thickness increase as the temperature gradient in the solid phase and the solidification rate increase. The developed theory allows us to determine analytically the permeability of the two-phase region and a characteristic interdendritic spacing in it. Analytical solutions show that the relative permeability in the two-phase region increases from a certain value at the interface with the solid phase to unity at the interface with the liquid phase. The selection theory of stable dendritic growth allows us to determine analytically a characteristic interdendritic distance in the two-phase layer that decreases as the temperature gradient in the solid phase increases. An increase of impurity in the molten phase gives a decrease in the interdendritic spacing within a two-phase region.

Mutability of Nucleation Particles in Reactive Salt Hydrate Phase Change Materials.

Nucleation particles, solid phases dispersed throughout a medium to decrease the energy barrier for solidification or other reversible phase transitions, are generally selected on the basis of structural or interfacial energy considerations between the host phase and the solid phase that is crystallizing. However, the existence of chemical reactions between the nucleation particles and the host phase can obscure these underlying relationships, thereby complicating the process of selection of active nucleation particle phases. Here, we reveal the origin of nucleation activity of barium-based nucleation particles in the salt hydrate calcium chloride hexahydrate (CCH), a candidate for near room temperature thermal energy storage. We demonstrate that these compounds undergo a series of cation exchange and secondary precipitation reactions, resulting in an assemblage of solid precipitates with some degree of limited solid solution, which collectively dramatically reduce undercooling in CCH, but which obscure the identification of a single crystalline phase primarily responsible for the nucleation of crystalline CCH from the liquid. Importantly, this result illustrates a pathway to harness in situ chemical reactions to generate stable active nucleation particles in reactive phase change materials, which may not be readily synthesized by alternative methods, or which may not be active or remain stable when added in isolation.

Solution and Surface Solvation of Nitrate Anions with Iron(III) and Aluminum(III) in Aqueous Environments: A Raman and Vibrational Sum Frequency Generation Study.

Hydrated trivalent metal nitrate salts, Fe(NO3)3·9H2O and Al(NO3)3·9H2O, in both solid and aqueous phases are investigated. Raman and surface-selective vibrational sum frequency generation (SFG) spectroscopy, are used to shed light on ion-ion interactions and hydration in several spectral regions spanning low frequency (440-550 cm-1) to higher frequency modes of nitrate and water (720, 1050, 1250-1450, and 2800-3750 cm-1). These frequencies span the metal-water mode, nitrate in-plane deformation, nitrate symmetric and asymmetric modes, and the OH stretch of condensed phase water molecules. Comparison to NaNO3, and in some cases KNO3, is also shown, providing insight. Splitting and frequency shifts are observed and discussed for both the solid state and solution phase. The Lewis acidity of Fe3+ and Al3+ ions plays a significant role in the observed spectra, in particular for the nitrate asymmetric band splitting and frequency shift. The spectral response from water solvation for iron and aluminum nitrates is nonlinear as compared to linear for sodium nitrate, suggesting significantly different solvation environments that are limited by water hydration capacity at higher concentrations. Moreover, a non-hydrogen bonded OH, dangling OH, from hydrating water molecules is observed spectroscopically for Al and Fe nitrate solutions. Furthermore, aluminum nitrate perturbs the surface water structure more than iron nitrate despite aluminum being a weaker Lewis acid. The surface water structure is thus found to be unique for the Al(NO3)3 solutions as compared to both Fe(NO3)3 and NaNO3, such that surface solvation is more pronounced. This observation exemplifies the nature of the Fe(III) and Al(III) ions and their substantial influence on the surface water structure.

Solid‐phase synthesis of silicalite‐1 molecular sieve based on fly ash and its CO2 adsorption performance

AbstractIn this work, an alkali melting‐pickling assisted solid phase synthesis method of S‐1 zeolite molecular sieve with excellent adsorption properties for CO2 was successfully developed by using solid waste fly ash. SiO2 with a purity of up to 97.84% was successfully extracted by using alkaline fusion activation, high temperature calcination and pickling. The CO2 adsorption capacity of the prepared SiO2 was 0.51 mmol/g at 298 K and 1 bar. Silicalite‐1 molecular sieve was prepared by solid phase synthesis method using SiO2 extracted from fly ash as silicon source. The results showed that the prepared Silicalite‐1 had good morphology and relatively high crystallinity. The specific surface area is 623.30 m2/g, and the total pore volume is 0.31 cm3/g. In addition, the adsorption capacity of CO2 was 2.05 mmol/g at 298 K and 1 bar. Compared with the prepared SiO2, the adsorption capacity of CO2 by Silicalite‐1 molecular sieve increased by four times. Moreover, under the test condition of 298 K, it has a high selectivity coefficient for CO2/N2 mixed gas, and after 10 times of adsorption‐desorption cycle tests, the adsorption capacity of Silicalite‐1 molecular sieve for CO2 does not change significantly, and its adsorption rate can still be as high as 89.31%. The results indicate that Silicalite‐1 molecular sieve prepared by solid phase synthesis method has good adsorption selectivity and adsorption–desorption cycle regeneration stability, and can be used in the field of CO2 adsorption, separation and purification. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

Thrombosis in Antiphospholipid Syndrome: Current Perspectives and Challenges in Laboratory Testing for Antiphospholipid Antibodies.

Antiphospholipid syndrome (APS) diagnosis hinges on identifying antiphospholipid antibodies (aPL). Currently, laboratory testing encompasses lupus anticoagulant (LA), anticardiolipin (aCL), and anti-β2-glycoprotein I antibodies (aβ2GPI) IgG or IgM, which are included in the APS classification criteria. All the assays needed to detect aPL antibodies have methodological concerns. LA testing remains challenging due to its complexity and susceptibility to interference from anticoagulant therapy. Solid phase assays for aCL and aβ2GPI exhibit discrepancies between different assays. Antibody profiles aid in identifying the patients at risk for thrombosis through integrated interpretation of all positive aPL tests. Antibodies targeting domain I of β2-glycoprotein and antiphosphatidylserine-prothrombin antibodies have been evaluated for their role in thrombotic APS but are not yet included in the APS criteria. Detecting these antibodies may help patients with incomplete antibody profiles and stratify the risk of APS patients. The added diagnostic value of other methodologies and measurements of other APS-associated antibodies are inconsistent. This manuscript describes laboratory parameters useful in the diagnosis of thrombotic APS and will concentrate on the laboratory aspects, clinical significance of assays, and interpretation of aPL results in the diagnosis of thrombotic APS.