Site-Specific Stability Evaluation of Antibody-Drug Conjugate in Serum Using a Validated Liquid Chromatography-Mass Spectrometry Method.

Antibody-drug conjugate (ADC) consists of engineered antibodies and cytotoxic drugs linked via a chemical linker, and the stability of ADC plays a crucial role in ensuring its safety and efficacy. The stability of ADC is closely related to the conjugation site; however, no method has been developed to assess the stability of different conjugation sites due to the low response of conjugated peptides. In this study, an integrated strategy was developed and validated to assess the stability of different conjugation sites on ADC in serum. Initial identification of the conjugated peptides of the model drug ado-trastuzumab emtansine (T-DM1) was achieved by the proteomic method. Subsequently, a semiquantitative method for conjugated peptides was established in liquid chromatography-hybrid linear ion trap triple quadrupole mass spectrometry (LC-QTRAP-MS/MS) based on the qualitative information. The pretreatment method of the serum sample was optimized to reduce matrix interference. The method was then validated and applied to evaluate the stability of the conjugation sites on T-DM1. The results highlighted differences in stability among the different conjugation sites on T-DM1. This is the first study to assess the stability of different conjugation sites on the ADC in serum, which will be helpful for the design and screening of ADCs in the early stages of development.

Identification of bile acids in snake bile by hydrogen/deuterium exchange mass spectrometry and quantitative structure-retention relationship analysis.

Natural bile acids, a class of steroids with a valeric acid side chain at the C-17 position, present significant challenges in separation and analysis due to structural similarities, isomerism, and large polarity differences. Therefore, advanced analytical methods are essential for the accurate identification and quantification of bile acids. This study conducted a comprehensive qualitative analysis of bile acids by integrating liquid chromatography-tandem mass spectrometry (LC-MS/MS), hydrogen-deuterium exchange tandem mass spectrometry (HDX-MS/MS), and quantitative structure-retention relationship (QSRR) methods. Firstly, LC-MS/MS conditions were optimized to enhance chromatographic separation and improve the reliability of characteristic fragment ions. MS/MS fragmentation rules for bile acids were derived from the mass spectral data of bile acid standards and validated through HDX-MS/MS experiments. Secondly, potential bile acids in snake bile were identified based on these validated fragmentation rules, and a QSRR model was established to predict the retention times of the proposed structures. Thirdly, HDX-MS/MS was applied to assist in identifying bile acid isomers. Finally, a total of 150 bile acids, including 11 free bile acids (free BA), 5 glyco-bile acids (GBA) and 134 tauro-bile acids (TBA), were detected in snake bile. Thirteen bile acids were accurately characterized by comparing their retention time and MS/MS spectra with standards. Forty-nine bile acids were reasonably annotated using the QSRR model and HDX-MS/MS. This study is notable for being the first to utilize the QSRR and HDX-MS/MS techniques for the annotation of bile acids in snake bile, providing a robust framework for the structural elucidation of these compounds.

Polyelectrolyte Additive-Modulated Interfacial Microenvironment Boosting CO2 Electrolysis in Acid.

Acidic CO2 electrolysis offers a promising strategy to achieve high carbon utilization and high energy efficiency. However, challenges remain in suppressing the competitive hydrogen evolution reaction (HER) and improving product selectivity. High concentrations of potassium ions (K+) can suppress HER and accelerate CO2 reduction, but they still inevitably suffer from salt precipitation problems. In this study, we demonstrate that the sulfonate-based polyelectrolyte, polystyrene sulfonate (PSS), enables to reconstruct the electrode-electrolyte interface to significantly enhance the acidic CO2 electrolysis. Mechanistic studies reveal that PSS induces high local K+ concentrations through electrostatic interaction between PSS anions and K+. In situ spectroscopy reveals that PSS reshapes the interfacial hydrogen-bond (H-bond) network, which is attributed to the H-bonds between PSS anions and hydrated proton as well as the steric hindrance of the additive molecules. This greatly weakens proton transfer kinetics and leads to the suppression of undesirable HER. As a result, a Faradaic efficiency of 93.9% for CO can be achieved at 250 mA cm-2, simultaneous with a high single-pass carbon efficiency of 72.2% on commercial Ag catalysts in acid. This study highlights the important role of the electrode-electrolyte interface induced by polyelectrolyte additives in promoting electrocatalytic reactions.

Anionic Surfactant-Tailored Interfacial Microenvironment for Boosting Electrochemical CO2 Reduction.

Both the catalyst and electrolyte deeply impact the performance of the carbon dioxide reduction reaction (CO2RR). It remains a challenge to design the electrolyte compositions for promoting the CO2RR. Here, typical anionic surfactants, dodecylphosphonic acid (DDPA) and its analogues, are employed as electrolyte additives to tune the catalysis interface where the CO2RR occurs. Surprisingly, the anionic surfactant-tailored interfacial microenvironment enables a set of typical commercial catalysts for the CO2RR to deliver a significantly enhanced selectivity of carbon products in both neutral and acidic electrolytes. Mechanistic studies disclose that the DDPA addition restructures the interfacial hydrogen-bond environment via increasing the weak H-bonded water, thus promoting the CO2 protonation to CO. Specifically, in an H-type cell, the Faradaic efficiency of CO increases from 70 to 98% at -1.0 V versus the reversible hydrogen electrode. Furthermore, in a flow cell, the DDPA-containing electrolyte maintains over 90% FECO from 50-400 mA cm-2. Additionally, this electrolyte modulation strategy can be extended to acidic CO2RR with a pH of 1.5-3.5.

Biodegradable Microembolics with Nanografted Polyanions Enable High-Efficiency Drug Loading and Sustained Deep-Tumor Drug Penetration for Locoregional Chemoembolization Treatment.

Transarterial chemoembolization (TACE), the mainstay treatment of unresectable primary liver cancer that primarily employs nondegradable drug-loaded embolic agents to achieve synergistic vascular embolization and locoregional chemotherapy effects, suffers from an inferior drug burst behavior lacking long-term drug release controllability that severely limits the TACE efficacy. Here we developed gelatin-based drug-eluting microembolics grafted with nanosized poly(acrylic acid) serving as a biodegradable ion-exchange platform that leverages a counterion condensation effect to achieve high-efficiency electrostatic drug loading with electropositive drugs such as doxorubicin (i.e., drug loading capacity >34 mg/mL, encapsulation efficiency >98%, and loading time <10 min) and an enzymatic surface-erosion degradation pattern (∼2 months) to offer sustained locoregional pharmacokinetics with long-lasting deep-tumor retention capability for TACE treatment. The microembolics demonstrated facile microcatheter deliverability in a healthy porcine liver embolization model, superior tumor-killing capacity in a rabbit VX2 liver cancer embolization model, and stabilized extravascular drug penetration depth (>3 mm for 3 months) in a rabbit ear embolization model. Importantly, the microembolics finally exhibited vessel remodeling-induced permanent embolization with minimal inflammation responses after complete degradation. Such a biodegradable ion-exchange drug carrier provides an effective and versatile strategy for enhancing long-term therapeutic responses of various local chemotherapy treatments.

Anionic Surfactant-Modulated Electrode-Electrolyte Interface Promotes H2O2 Electrosynthesis.

Conventional strategies for highly selective and active hydrogen peroxide (H2O2) electrosynthesis primarily focus on catalyst design. Electrocatalytic reactions take place at the electrified electrode-electrolyte interface. Well-designed electrolytes, when combined with commercial catalysts, can be directly applied to high-efficiency H2O2 electrosynthesis. However, the role of electrolyte components is equally crucial but is significantly under-researched. In this study, anionic surfactant n-tetradecylphosphonic acid (TDPA) and its analogs are used as electrolyte additives to enhance the selectivity of the two-electron oxygen reduction reaction. Mechanistic studies reveal that TDPA assembled over the electrode-electrolyte interface modulates the electrical double-layer structure, which repels interfacial water and weakens the hydrogen-bond network for proton transfer. Additionally, the hydrophilic phosphonate moiety affects the coordination of water molecules in the solvation shell, thereby directly influencing the proton-coupled kinetics at the interface. The TDPA-containing catalytic system achieves a Faradaic efficiency of H2O2 production close to 100% at a current density of 200 mA cm-2 using commercial carbon black catalysts. This research provides a simple strategy to enhance H2O2 electrosynthesis by adjusting the interfacial microenvironment through electrolyte design.

Emulsion-Based Multi-Phase Integrated Microbeads with Inner Multi-Interface Structure Enable Dual-Modal Imaging for Precision Endovascular Embolization.

Microsphere-based embolic agents have gained prominence in transarterial embolization (TAE) treatment, a critical minimally invasive therapy widely applied for a variety of diseases such as hypervascular tumors and acute bleeding. However, the development of microspheres with long-term, real-time, and repeated X-ray imaging as well as ultrasound imaging remains challenging. In this study, emulsion-based dual-modal imaging microbeads with a unique internal multi-interface structure is developed for TAE treatment. The embolic microbeads are fabricated from a solidified oil-in-water (O/W) emulsion composed of crosslinked CaAlg-based aqueous matrix and dispersed radiopaque iodinated oil (IO) droplets through a droplet-based microfluidic fabrication method. The CaAlg-IO microbeads exhibit superior X-ray imaging visibility due to the incorporation of exceptionally high iodine level up to 221 mgI mL-1, excellent ultrasound imaging capability attributed to the multi-interface structure of the O/W emulsion, great microcatheter deliverability thanks to their appropriate biomechanical properties and optimal microbead density, and extended drug release behavior owing to the biodegradation nature of the embolics. Such an embolic agent presents a promising emulsion-based platform to utilize multi-phased structures for improving endovascular embolization performance and assessment capabilities.

Direct extraction of ten estrogens from milk samples with DVB/NVP-modified magnetic solid-phase extraction adsorbent followed by pre-column derivatization-UHPLC-MS/MS.

Estrogens and their analogues can cause harm to human health through the food chain. Ten estrogens in different milk samples were directly extracted by amphiphilic divinylbenzene/N-vinyl-2-pyrrolidone (DVB/NVP)-Fe3O4@SiO2-based magnetic solid-phase extraction (MSPE) followed by pre-column derivatization and ultra-high performance liquid chromatography tandem mass-spectrometry (UHPLC-MS/MS) detection. Under the optimal conditions, the limits of detection for ten analytes were in the range of 0.05-0.38 ng mL-1 in whole liquid milk matrix and 0.04-3.00 ng g-1 in milk powder matrix. The intra-/inter-day accuracy ranged in 83.4-113.8%, with RSDs in 2.5-15.0%. A total of 15 brands of liquid milk and milk powder samples were analyzed, and only estradiol was detected in three brands of boxed liquid milk within safe range. The proposed sample pretreatment eliminated the common protein precipitation process, improved the sample throughput, and has the potential for routine testing of estrogens and their analogues in market-sale milk samples.

Lewis-base ligand-reshaped interfacial hydrogen-bond network boosts CO2 electrolysis.

Both the catalyst and electrolyte strongly impact the performance of CO2 electrolysis. Despite substantial progress in catalysts, it remains highly challenging to tailor electrolyte compositions and understand their functions at the catalyst interface. Here, we report that the ethylenediaminetetraacetic acid (EDTA) and its analogs, featuring strong Lewis acid-base interaction with metal cations, are selected as electrolyte additives to reshape the catalyst-electrolyte interface for promoting CO2 electrolysis. Mechanistic studies reveal that EDTA molecules are dynamically assembled toward interface regions in response to bias potential due to strong Lewis acid-base interaction of EDTA4--K+. As a result, the original hydrogen-bond network among interfacial H2O is disrupted, and a hydrogen-bond gap layer at the electrified interface is established. The EDTA-reshaped K+ solvation structure promotes the protonation of *CO2 to *COOH and suppressing *H2O dissociation to *H, thereby boosting the co-electrolysis of CO2 and H2O toward carbon-based products. In particular, when 5 mM of EDTA is added into the electrolytes, the Faradaic efficiency of CO on the commercial Ag nanoparticle catalyst is increased from 57.0% to 90.0% at an industry-relevant current density of 500 mA cm-2. More importantly, the Lewis-base ligand-reshaped interface allows a range of catalysts (Ag, Zn, Pd, Bi, Sn, and Cu) to deliver substantially increased selectivity of carbon-based products in both H-type and flow-type electrolysis cells.

Surfactant Directionally Assembled at the Electrode-Electrolyte Interface for Facilitating Electrocatalytic Aldehyde Hydrogenation.

Electrocatalytic hydrogenation of unsaturated aldehydes to unsaturated alcohols is a promising alternative to conventional thermal processes. Both the catalyst and electrolyte deeply impact the performance. Designing the electrode-electrolyte interface remains challenging due to its compositional and structural complexity. Here, we employ the electrocatalytic hydrogenation of 5-hydroxymethylfurfural (HMF) as a reaction model. The typical cationic surfactant, cetyltrimethylammonium bromide (CTAB), and its analogs are employed as electrolyte additives to tune the interfacial microenvironment, delivering high-efficiency hydrogenation of HMF and inhibition of the hydrogen evolution reaction (HER). The surfactants experience a conformational transformation from stochastic distribution to directional assembly under applied potential. This oriented arrangement hampers the transfer of water molecules to the interface and promotes the enrichment of reactants. In addition, near 100 % 2,5-bis(hydroxymethyl)furan (BHMF) selectivity is achieved, and the faradaic efficiency (FE) of the BHMF is improved from 61 % to 74 % at -100 mA cm-2. Notably, the microenvironmental modulation strategy applies to a range of electrocatalytic hydrogenation reactions involving aldehyde substrates. This work paves the way for engineering advanced electrode-electrolyte interfaces and boosting unsaturated alcohol electrosynthesis efficiency.

Ultrastable Iodinated Oil-Based Pickering Emulsion Enables Locoregional Sustained Codelivery of Hypoxia Inducible Factor-1 Inhibitor and Anticancer Drugs for Tumor Combination Chemotherapy.

Tumor hypoxia-associated drug resistance presents a major challenge for cancer chemotherapy. However, sustained delivery systems with a high loading capability of hypoxia-inducible factor-1 (HIF-1) inhibitors are still limited. Here, we developed an ultrastable iodinated oil-based Pickering emulsion (PE) to achieve locally sustained codelivery of a HIF-1 inhibitor of acriflavine and an anticancer drug of doxorubicin for tumor synergistic chemotherapy. The PE exhibited facile injectability for intratumoral administration, great radiopacity for in vivo examination, excellent physical stability (>1 mo), and long-term sustained release capability of both hydrophilic drugs (i.e., acriflavine and doxorubicin). We found that the codelivery of acriflavine and doxorubicin from the PE promoted the local accumulation and retention of both drugs using an acellular liver organ model and demonstrated significant inhibition of tumor growth in a 4T1 tumor-bearing mouse model, improving the chemotherapeutic efficacy through the synergistic effects of direct cytotoxicity with the functional suppression of HIF-1 pathways of tumor cells. Such an iodinated oil-based PE provides a great injectable sustained delivery platform of hydrophilic drugs for locoregional chemotherapy.

Mechanistic Insights into Surfactant-Modulated Electrode-Electrolyte Interface for Steering H2O2 Electrosynthesis.

Electrocatalytic reactions taking place at the electrified electrode-electrolyte interface involve processes of proton-coupled electron transfer. Interfacial protons are delivered to the electrode surface via a H2O-dominated hydrogen-bond network. Less efforts are made to regulate the interfacial proton transfer from the perspective of interfacial hydrogen-bond network. Here, we present quaternary ammonium salt cationic surfactants as electrolyte additives for enhancing the H2O2 selectivity of the oxygen reduction reaction (ORR). Through in situ vibrational spectroscopy and molecular dynamics calculation, it is revealed that the surfactants are irreversibly adsorbed on the electrode surface in response to a given bias potential range, leading to the weakening of the interfacial hydrogen-bond network. This decreases interfacial proton transfer kinetics, particularly at high bias potentials, thus suppressing the 4-electron ORR pathway and achieving a highly selective 2-electron pathway toward H2O2. These results highlight the opportunity for steering H2O-involved electrochemical reactions via modulating the interfacial hydrogen-bond network.

Molecular targets of cisplatin in HeLa cells explored through competitive activity-based protein profiling strategy.

Cisplatin is widely used as anticancer drugs, and DNA is considered as the main target. Considering its high affinity towards cysteines and the important role of cystine containing proteins, we applied a competitive activity-based protein profiling strategy to identify protein cysteines that bind with cisplatin in HeLa cells. Living cells were treated with cisplatin at cytotoxic concentrations, then the protein was extracted. After labeling with desthiobiotin iodoacetamide (DBIA) probe, protein was precipitated, digested and isotopically labeled, subsequently the peptides were combined, and the biotinylated cysteine-containing peptides were enriched and quantified by LC-MS/MS. A total of 3571 peptides which originated from 1871 proteins were identified using the DBIA probe. Among them, 46 proteins were screened as targets, including proteins that have been identified as binding proteins by previous study. A novel cisplatin target, calpain-1 (CAPN1), was identified and validated as binding with cisplatin in vitro.

Exact Operator Map from Strong Coupling to Free Fields: Beyond Seiberg-Witten Theory.

In quantum field theory above two spacetime dimensions, one is usually only able to construct exact operator maps from UV to IR of strongly coupled renormalization group flows for the most symmetry-protected observables. Famous examples include maps of chiral rings in 4D N=2 supersymmetry. In this Letter, we construct the first nonperturbative UV-IR map for less protected operators: starting from a particularly "simple" UV strongly coupled non-Lagrangian 4D N=2 quantum field theory, we show that a universal nonchiral quarter-Bogomol'nyi-Prasad-Sommerfield ring can be mapped exactly and bijectively to the IR. In particular, strongly coupled UV dynamics governing infinitely many null states manifest in the IR via Fermi statistics of free gauginos. Using the concept of arc space, this bijection allows us to compute the exact UV Macdonald index in the IR.

Post-transfusion severe headache in a patient with thalassemia with superficial siderosis of the central nervous system: a case report and literature review.

BACKGROUND: Patients with severe thalassemia may experience adverse effects from transfusion such as fever, rash, and iron overload after long-term transfusion therapy. Severe headaches as a side effect of blood transfusion in patients with thalassemia are not commonly observed, especially when combined with superficial siderosis of the central nervous system, which is easily misdiagnosed and requires excessive examination and treatment. CASE PRESENTATION: A 31-year-old woman was admitted with severe headache and vomiting over 3 days following blood transfusion. She was diagnosed with intermediate α-thalassemia at 2 years of age and had a history of irregular blood transfusions. Physical examination revealed horizontal nystagmus with no other abnormal neurological signs. Magnetic resonance (MR) imaging, MR venography, MR arteriography, and cerebrospinal fluid analysis were normal. However, susceptibility-weighted imaging showed abnormal signals in the bilateral and fourth ventricles. Initial antibiotics, antivirals, decompression of intracranial pressure, iron chelation, and symptomatic treatments were administered; subsequently, small intermittent blood transfusions were cautiously administered for severe anemia. The patient's headache was gradually relieved, and she was discharged on day 9. At the 5-month follow-up, the patient's headache recurred following another transfusion. CONCLUSIONS: Severe post-transfusion headache in patients with thalassemia has not been fully recognized and is easily misdiagnosed, leading to excessive examination and treatment. Understanding the clinical features of transfusion-related headaches can help identify this complication, but the exact pathophysiological mechanism requires further research.

Effect of food and polymorphisms in SLCO2B1, CYP3A4 and UGT1A4 on pharmacokinetics of abiraterone and its metabolites in Chinese volunteers.

AIMS: Abiraterone acetate, a prodrug of abiraterone (ABI), provides an efficient therapeutic option for metastatic castration-resistant prostate cancer patients. ABI undergoes extensive metabolism in vivo and is transformed into active metabolites Δ4 -abiraterone and 3-keto-5α-abiraterone as well as inactive metabolites abiraterone sulfate and abiraterone N-oxide sulfate. We aimed to examine the effect of polymorphisms in SLCO2B1, CYP3A4 and UGT1A4 on the pharmacokinetics of ABI and its metabolites. METHODS: In this study, 81 healthy Chinese subjects were enrolled and divided into 2 groups for fasted (n = 45) and fed (n = 36) studies. Plasma samples were collected after administering a 250 mg abiraterone acetate tablet followed by liquid chromatography-tandem mass spectrometry analysis. Genotyping was performed on a MassARRAY system. The association between SLCO2B1, CYP3A4, UGT1A4 genotype and pharmacokinetic parameters of ABI and its metabolites was assessed. RESULTS: Food effect study demonstrated high fat meal remarkedly increased systemic exposure of ABI and its metabolites. The geometric mean ratio and 90% confidence interval of area under the plasma concentration-time curve from time 0 to the time of the last quantifiable concentration (AUC0-t ) and maximum plasma concentration (Cmax ) of ABI in fed state vs. fasted state were 351.64% (286.86%-431.04%) and 478.45% (390.01%-586.94%), respectively, while the corresponding results were ranging from 145.11% to 269.42% and 150.10% to 478.45% for AUC0-t and Cmax of ABI metabolites in fed state vs. fasted state, respectively. The SLCO2B1 rs1077858 had a significant influence on AUC0-t and Cmax , while 7 other SLCO2B1 variants prolonged half-life of ABI under both fasted and fed conditions. As for ABI metabolites, the systemic exposure of Δ4 -abiraterone, abiraterone sulfate and abiraterone N-oxide sulfate as well as the elimination of 3-keto-5α-abiraterone were significantly affected by SLCO2B1 polymorphisms. Polymorphisms in CYP3A4 and UGT1A4 did not significantly affect pharmacokinetics of ABI and its metabolites. CONCLUSION: Polymorphisms in SLCO2B1 were significantly related to the pharmacokinetic variability of ABI and its metabolites under both fasted and fed conditions.

First-in-human trial of SAR107375E, a novel small molecule anticoagulant with dual inhibition of factor Xa and factor IIa.

BACKGROUND: SAR107375E is a direct dual inhibitor of both Factor Xa and Factor IIa and has shown potent anticoagulation activity in vitro and animals. This study evaluated the safety, tolerability, pharmacokinetics, and pharmacodynamics of single ascending intravenous doses of SAR107375E in healthy Chinese adult subjects. METHODS: In this randomized, double-blind, placebo-controlled trial, 60 healthy Chinese adult subjects were administered intravenously single ascending doses (0.5, 1.5, 3.0, 5.0, 7.5, 10.0, 15.0, or 20.0 mg) of SAR107375E (N = 44) or placebo (N = 16). Plasma and urine concentrations of SAR107375E were measured and used to calculate pharmacokinetic parameters. Coagulation functions were measured and compared with baseline values. Treatment-emergent adverse events were recorded to evaluate safety. RESULTS: In plasma, from the 0.5 to 20.0 mg dose group, t1/2 is 1.51-4.00 h, Cmax is 59.05-1360 ug/L, and AUC0-t is 25.01-528.45 h*ug/L. And it shows dose proportionality in the 5.0-20.0 mg range. Activated partial thromboplastin time and Ecarin clotting time correlated linearly with drug plasma concentration. No serious adverse events were reported during the study. CONCLUSION: SAR107375E exhibits good safety and tolerability, predictable pharmacokinetics and pharmacodynamics. CLINICAL TRIAL REGISTRATION: www.chinadrugtrials.org.cn, identifier is CTR20211082.

Characteristics of amino acid metabolism in colorectal cancer.

In recent years, metabolomics research has become a hot spot in the screening and treatment of cancer. It is a popular technique for the quantitative characterization of small molecular compounds in biological cells, tissues, organs or organisms. Further study of the tumor revealed that amino acid changes may occur early in the tumor. The rapid growth and metabolism required for survival result in tumors exhibiting an increased demand for amino acids. An abundant supply of amino acids is important for cancer to maintain its proliferative driving force. Changes in amino acid metabolism can be used to screen malignant tumors and improve therapeutic outcomes. Therefore, it is particularly important to study the characteristics of amino acid metabolism in colorectal cancer. This article reviews several specific amino acid metabolism characteristics in colorectal cancer.

Rh-dispersed Cu nanowire catalyst for boosting electrocatalytic hydrogenation of 5-hydroxymethylfurfural.

Electrocatalytic conversion of biomass-derived 5-hydroxymethylfurfural (HMF) to 2,5-bis(hydroxymethyl)furan (BHMF) presents a compelling strategy for the production of premium chemicals via the utilization of renewable energy sources. Exploring efficient catalytic systems to obtain highly selective BHMF has remained a giant challenge. A design strategy is proposed here to regulate active hydrogen (Hads) production in rhodium (Rh) nanoparticles grown on Cu nanowires (RhCu NWs) catalyst, which achieves a faradaic efficiency (FE) of 92.6% in the electrocatalytic reduction of HMF to BHMF at -20 mA cm-2 with no degradation in performance after 8 cycles. Kinetic investigations and electron spin resonance (ESR) spectroscopy reveal that the incorporation of Rh accelerates the water dissociation and facilitates the generation of Hads. In situ attenuated total reflection surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) further demonstrates that the Rh component boosts the proportion of ordered weakly hydrogen-bonded water molecules on the catalyst surface, which is much easier to dissociate. The construction of an interfacial Hads-rich environment promotes the HMF intermediates binding with Hads to BMHF, thereby suppressing the formation of undesired dimers. This work demonstrates the promise of altering the interfacial water environment as a strategy to boost the electrosynthetic properties of biomass-derived products toward value-added outcomes.

Identification of endogenous carbonyl steroids in human serum by chemical derivatization, hydrogen/deuterium exchange mass spectrometry and the quantitative structure-retention relationship.

Steroids are tetracyclic aliphatic compounds, and most of them contain carbonyl groups. The disordered homeostasis of steroids is closely related to the occurrence and progression of various diseases. Due to high structural similarity, low concentrations in vivo, poor ionization efficiency, and interference from endogenous substances, it is very challenging to comprehensively and unambiguously identify endogenous steroids in biological matrix. Herein, an integrated strategy was developed for the characterization of endogenous steroids in serum based on chemical derivatization, ultra-performance liquid chromatography quadrupole Exactive mass spectrometry (UPLC-Q-Exactive-MS/MS), hydrogen/deuterium (H/D) exchange, and a quantitative structure-retention relationship (QSRR) model. To enhance the mass spectrometry (MS) response of carbonyl steroids, the ketonic carbonyl group was derivatized by Girard T (GT). Firstly, the fragmentation rules of derivatized carbonyl steroid standards by GT were summarized. Then, carbonyl steroids in serum were derivatized by GT and identified based on the fragmentation rules or by comparing retention time and MS/MS spectra with those of standards. H/D exchange MS was utilized to distinguish derivatized steroid isomers for the first time. Finally, a QSRR model was constructed to predict the retention time of the unknown steroid derivatives. With this strategy, 93 carbonyl steroids were identified from human serum, and 30 of them were determined to be dicarbonyl steroids by the charge number of characteristic ions and the number of exchangeable hrdrogen or comparing with standards. The QSRR model built by the machine learning algorithms has an excellent regression correlation, thus the accurate structures of 14 carbonyl steroids were determined, among which three steroids were reported for the first time in human serum. This study provides a new analytical method for the comprehensive and reliable identification of carbonyl steroids in biological matrix.