Nanoparticle Deep-Subwavelength Dynamics Empowered by Optical Meron-Antimeron Topology.

Optical meron is a type of nonplanar topological texture mainly observed in surface plasmon polaritons and highly symmetric points of photonic crystals in the reciprocal space. Here, we report Poynting-vector merons formed at the real space of a photonic crystal for a Γ-point illumination. Optical merons can be utilized for subwavelength-resolution manipulation of nanoparticles, resembling a topological Hall effect on electrons via magnetic merons. In particular, staggered merons and antimerons impose strong radiation pressure on large gold nanoparticles (AuNPs), while focused hot spots in antimerons generate dominant optical gradient forces on small AuNPs. Synergistically, differently sized AuNPs in a still environment can be trapped or orbit in opposite directions, mimicking a coupled galaxy system. They can also be separated with a 10 nm precision when applying a flow velocity of >1 mm/s. Our study unravels a novel way to exploit topological textures for optical manipulation with deep-subwavelength precision and switchable topology in a lossless environment.

Investigation of the synergistic effect mechanism underlying sequential use of palbociclib and cisplatin through integral proteomic and glycoproteomic analysis.

Chemoresistance largely hampers the clinical use of chemodrugs for cancer patients, combination or sequential drug treatment regimens have been designed to minimize chemotoxicity and resensitize chemoresistance. In this work, the cytotoxic effect of cisplatin was found to be enhanced by palbociclib pretreatment in HeLa cells. With the integration of liquid chromatography-mass spectrometry-based proteomic and N-glycoproteomic workflow, we found that palbociclib alone mainly enhanced the N-glycosylation alterations in HeLa cells, while cisplatin majorly increased the different expression proteins related to apoptosis pathways. As a result, the sequential use of two drugs induced a higher expression level of apoptosis proteins BAX and BAK. Those altered N-glycoproteins induced by palbociclib were implicated in pathways that were closely associated with cell membrane modification and drug sensitivity. Specifically, the top four frequently glycosylated proteins FOLR1, L1CAM, CD63, and LAMP1 were all associated with drug resistance or drug sensitivity. It is suspected that palbociclib-induced N-glycosylation on the membrane protein allowed the HeLa cell to become more vulnerable to cisplatin treatment. Our study provides new insights into the mechanisms underlying the sequential use of target drugs and chemotherapy drugs, meanwhile suggesting a high-efficiency approach that involves proteomic and N-glycoproteomic to facilitate drug discovery.

Development of cancer biomarker heat shock protein 90α certified reference material using two different isotope dilution mass spectrometry techniques.

Heat shock protein 90α (HSP90α) has been regarded as an important indicator for judging tumor metastasis and prognosis due to its significant upregulation in various tumors. Therefore, the accurate quantification of HSP90α is of great significance for clinical diagnosis and therapy of cancers. However, the lack of HSP90α certified reference material (CRM) leads to the accuracy and consistency of quantification methods not being effectively evaluated. Besides, quantitative results without traceability make comparisons between different studies difficult. In this study, an HSP90α solution CRM was developed from the recombinant protein raw material. The recombinant protein is a dimer, and the purity of the CRM candidate reached 96.71%. Both amino acid analysis-isotope dilution mass spectrometry (AAA-IDMS) and unique peptide analysis-isotope dilution mass spectrometry (UPA-IDMS) were performed to measure the content of HSP90α in the solution CRM candidate, and the certified value was assessed to be 66.2 ± 8.8 µg/g. Good homogeneity of the CRM was identified, and the stability examination suggested that the CRM was stable for at least 4 months at - 80 °C and for 7 days at 4 °C. With traceability to SI unit (kg), this CRM has potential to help establish a metrological traceability chain for quantification of HSP90α, which will make the quantification results standardized and comparable regardless of the quantitative methods.

Facial emotion recognition function and white matter microstructural alterations in drug-naive, comorbidity-free autism.

Individuals with autism spectrum disorder have deficits in facial emotion recognition and white matter microstructural alterations. Nonetheless, most previous studies were confounded by different variables, such as psychiatric comorbidities and psychotropic medications used by ASD participants. Also, it remains unclear how exactly FER deficits are related to white matter microstructural alterations in ASD. Accordingly, we aimed to investigate the FER functions, white matter microstructure, and their relationship in drug-naive and comorbidity-free ASD individuals. 59 ASD individuals and 59 typically developed individuals were included, where 46 ASD and 50 TD individuals completed FER tasks. Covariance analysis showed scores were lower in both basic and complex FER tasks in the ASD group. Tract-Based Spatial Statistics showed FA values in widespread white matter fibers were lower in the ASD group than in the TD group, including forceps major and forceps minor of the corpus callosum, anterior thalamic radiation, corticospinal tract, cingulum, inferior frontal-occipital fasciculus, inferior longitudinal fasciculus, superior longitudinal fasciculus. Moreover, in the TD group but not the ASD group, the performance in the complex FER task was negatively correlated with the FA value in some white matter fibers, including forceps major of the corpus callosum, ATR, CT, cingulum, IFOF, ILF, SLF. Our study suggests children with ASD may experience deficits in facial emotion recognition and exhibit alterations in white matter microstructure. More importantly, our study indicates that white matter microstructural alterations may be involved in FER deficits in children with ASD.

Precise Control of Trypsin Immobilization by a Programmable DNA Tetrahedron Designed for Ultrafast Proteome Digestion and Accurate Protein Quantification.

In proteomics research, with advantages including short digestion times and reusable applications, immobilized enzyme reactors (IMERs) have been paid increasing attention. However, traditional IMERs ignore the reasonable spatial arrangement of trypsin on the supporting matrixes, resulting in the partial overlapping of the active domain on trypsin and reducing digesting efficiency. In this work, a DNA tetrahedron (DNA TET)-based IMER Fe3O4-GO-AuNPs-DNA TET-Trypsin was designed and prepared. The distance between vertices of DNA TETs effectively controls the distribution of trypsin on the nanomaterials; thus, highly efficient protein digestion and accurate quantitative results can be achieved. Compared to the in-solution digestion (12-16 h), the sequence coverage of bovine serum albumin was up to 91% after a 2-min digestion by the new IMER. In addition, 3328 proteins and 18,488 peptides can be identified from HeLa cell protein extract after a 20-min digestion. For the first time, human growth hormone reference material was rapidly and accurately quantified after a 4-h digestion by IMER. Therefore, this new IMER has great application potential in proteomics research and SI traceable quantification.

A Homeotic Mutation Changes Legume Nodule Ontogeny into Actinorhizal-Type Ontogeny.

Some plants fix atmospheric nitrogen by hosting symbiotic diazotrophic rhizobia or Frankia bacteria in root organs known as nodules. Such nodule symbiosis occurs in 10 plant lineages in four taxonomic orders: Fabales, Fagales, Cucurbitales, and Rosales, which are collectively known as the nitrogen-fixing clade. Nodules are divided into two types based on differences in ontogeny and histology: legume-type and actinorhizal-type nodules. The evolutionary relationship between these nodule types has been a long-standing enigma for molecular and evolutionary biologists. Recent phylogenomic studies on nodulating and nonnodulating species in the nitrogen-fixing clade indicated that the nodulation trait has a shared evolutionary origin in all 10 lineages. However, this hypothesis faces a conundrum in that legume-type and actinorhizal-type nodules have been regarded as fundamentally different. Here, we analyzed the actinorhizal-type nodules formed by Parasponia andersonii (Rosales) and Alnus glutinosa (Fagales) and found that their ontogeny is more similar to that of legume-type nodules (Fabales) than generally assumed. We also show that in Medicago truncatula, a homeotic mutation in the co-transcriptional regulator gene NODULE ROOT1 (MtNOOT1) converts legume-type nodules into actinorhizal-type nodules. These experimental findings suggest that the two nodule types have a shared evolutionary origin.

Nanoliter atmospheric pressure photoionization-mass spectrometry for direct bioanalysis of polycyclic aromatic hydrocarbons.

Polycyclic aromatic hydrocarbons (PAHs) are a class of low-polarity environmental contaminants that have severe carcinogenic effects and have drawn worldwide attention. However, there remain challenges for current mass spectrometric ionization techniques in the analysis of low-polarity compounds in small-volume biosamples, such as single cells. In this work, we developed a nanoliter atmospheric pressure photoionization (nano-APPI) source and optimized its parameters for the detection of PAHs in small-volume samples. We evaluated the ionization performance of the source in direct and auxiliary gas-assisted photoionization modes and analyzed different PAH compounds as well as spiked biosamples. By combining the advantages of nano-electrospray ionization (nano-ESI) and atmospheric pressure photoionization (APPI), our newly developed nano-APPI source achieved high sensitivity for the analysis of PAHs down to the fmol level. Compared to conventional atmospheric pressure chemical ionization (APCI), the detection limit of PAHs was increased by 1-2 orders of magnitude. By optimizing various parameters, we achieved highly efficient ionization of PAHs, effective analysis of PAHs in mixed components, and sensitive detection of low-abundance PAHs in single-cell samples. Our optimized nano-APPI source was successfully applied for the sensitive analysis of PAHs in complex biological samples. Based on our study, we believe that nano-APPI holds great promise for toxicological studies on complex biological samples. The present work has implications for improving the detection sensitivity of low-polarity environmental contaminants and advancing the field of MS-based analysis of small-volume biosamples.

Autistic children's visual sensitivity to face movement.

There is a pressing need for studies of large sample sizes and variable age ranges to delineate the mechanism underlying reduced visual attention to biological motion in autism. Here we focused on the basic movement of the eyes or mouth in guiding attention. The stimuli face blinked continuously or moved the mouth silently. In a large sample (145 autistic and 132 non-autistic participants) ranging from 3 to 17 years old, we assessed whether autistic participants showed reduced visual attention to basic movement of the eyes or mouth using a free-viewing eye-tracking task. We found that, like non-autistic participants, autistic participants increased their eye-looking time when viewing the blinking face and increased mouth-looking time when viewing the mouth-moving face. Furthermore, these effects were stable across ages, suggesting the presence of a developmentally stable attentional capture by basic face movements in both groups. We also found that autistic participants looked less at basic face movement than non-autistic participants. Our results suggest that autistic children and adolescents could modulate their visual attention to the basic face movements, but their modulation effect is weaker than non-autistic participants. These results further our understanding of the mechanism underlying visual attention-to-face movement in autistic people.

Quantification of 25OHD in serum by ID-LC-MS/MS based on oriented immobilization of antibody on magnetic materials.

Magnetic nanomaterials are widely used, but co-adsorption of impurities will lead to saturation. In this study, the aim was to prepare a magnetic nano-immunosorbent material based on orienting immobilization that can purify and separate 25-hydroxyvitamin D (25OHD) from serum and provides a new concept of sample pretreatment technology. Streptococcus protein G (SPG) was modified on the surface of the chitosan magnetic material, and the antibody was oriented immobilized using the ability of SPG to specifically bind to the Fc region of the monoclonal antibody. The antigen-binding domain was fully exposed and made up for the deficiency of the antibody random immobilization. Compared with the antibody in the random binding format, this oriented immobilization strategy can increase the effective activity of the antibody, and the amount of antibody consumed is saved to a quarter of the former. The new method is simple, rapid, and sensitive, without consuming a lot of organic reagents, and can enrich 25OHD after simple protein precipitation. Combining with liquid chromatography-tandem mass spectrometry (LC-MS/MS), the analysis can be completed in less than 30 min. For 25OHD2 and 25OHD3, the LOD was 0.021 and 0.017 ng mL-1, respectively, and the LOQ was 0.070 and 0.058 ng mL-1, respectively. The results indicated that the magnetic nanomaterials based on oriented immobilization can be applied as an effective, sensitive, and attractive adsorbent to the enrichment of serum 25OHD.

Traceable value of immunoglobulin G against receptor-binding domain of SARS-CoV-2 confirmation and application to point-of-care testing system development.

A highly purified and bioactive immunoglobulin G monoclonal antibody against receptor-binding domain of SARS-CoV-2 (RBD-IgG-MAb) has been accurately quantified by amino acid determination using isotope dilution liquid chromatography-mass spectrometry. Absolute quantification of RBD-IgG-MAb was achieved by averaging 4 amino acid certified reference materials, which allows the quantitative value (66.1 ± 5.8 µg/L) to be traced to SI unit (mol). Afterwards, the RBD-IgG-MAb was employed as control and calibration compound for the development of a point-of-care testing (POCT) system based on colloidal gold lateral flow immunoassay, which aimed to rapidly and accurately detect the level of protective RBD-IgG after vaccination. Under the detection parameters, a sigmoidal curve has been plotted between signal intensity and the logarithmic concentration for quantitative detection with the limit of detection of about 0.39 µg/mL. The relative standard deviations of intra-assay and inter-assay were lower than 2.3% and 14%, and the recoveries ranged from 87 to 100%, respectively. Fingertip blood samples from 37 volunteers after vaccination were analyzed by the POCT system; results showed that levels of RBD-IgG in 33 out of 37 samples ranged from 0.45 to 2.46 µg/mL with the average level of 0.91 µg/mL. The developed POCT system has been successfully established with the quantity-traceability RBD-IgG-MAb as control and calibration compound, and the scientific contribution of this work can be promoted to other areas.

A CCaMK/Cyclops response element in the promoter of Lotus japonicus calcium-binding protein 1 (CBP1) mediates transcriptional activation in root symbioses.

Early gene expression in arbuscular mycorrhiza (AM) and the nitrogen-fixing root nodule symbiosis (RNS) is governed by a shared regulatory complex. Yet many symbiosis-induced genes are specifically activated in only one of the two symbioses. The Lotus japonicus T-DNA insertion line T90, carrying a promoterless uidA (GUS) gene in the promoter of Calcium Binding Protein 1 (CBP1) is exceptional as it exhibits GUS activity in both root endosymbioses. To identify the responsible cis- and trans-acting factors, we subjected deletion/modification series of CBP1 promoter : reporter fusions to transactivation and spatio-temporal expression analysis and screened ethyl methanesulphonate (EMS)-mutagenized T90 populations for aberrant GUS expression. We identified one cis-regulatory element required for GUS expression in the epidermis and a second element, necessary and sufficient for transactivation by the calcium and calmodulin-dependent protein kinase (CCaMK) in combination with the transcription factor Cyclops and conferring gene expression during both AM and RNS. Lack of GUS expression in T90 white mutants could be traced to DNA hypermethylation detected in and around this element. We concluded that the CCaMK/Cyclops complex can contribute to at least three distinct gene expression patterns on its direct target promoters NIN (RNS), RAM1 (AM), and CBP1 (AM and RNS), calling for yet-to-be identified specificity-conferring factors.

Investigation on the binary ionization choices for large conjugated amines during electrospray ionization.

RATIONALE: Generally, amines form protonated cations ([M + H]+ ) in positive polarity during electrospray ionization (ESI). However, it was found that large conjugated amines (LCAs) had binary ionization choices of generating either radical cations (M•+ ) or [M + H]+ during ESI. Investigation on the mechanism would further our understanding of ESI. METHODS: In this work, the binary ionization behavior of LCAs was reported and studied. Internal factors (functional groups and sizes of conjugated systems) and external factors (solvent type, flow rate, and electrode position) were systematically investigated and discussed. RESULTS: For the internal factors, electron-donating groups and large conjugated structures of LCAs were conducive to the generation of M•+ . For the external factors, aprotic solvent, higher flow rate, and shorter distance from the electrode to the spray cone facilitated the formation of M•+ but hampered the generation of [M + H]+ . CONCLUSION: The present study illustrated that the formations of M•+ and [M + H]+ for LCAs were two independent processes. The M•+ cations of LCAs were formed on the surface of the electrode through electrochemical oxidation, whereas the [M + H]+ cations were generated following the typical ESI evolution process. By regulating the external factors, the ionization results of LCAs could be well modulated.

Analysis of low-abundance molecules in complex matrices by quadrupole-linear ion trap mass spectrometry using a simultaneous fragmentation and accumulation strategy.

RATIONALE: Fast and sensitive analysis of low-abundance molecules in complex matrices has always been a challenge in chemical and biological applications. Mass spectrometry (MS) has been widely used in the fields of chemical and biological analysis due to its unparalleled specificity and sensitivity. However, the MS signals consistently deteriorate in the presence of matrices. Demands for more sensitive and efficient methods to analyze those low-abundance molecules in chemical and biological systems are in urgent need. METHODS: Based on a home-made quadrupole-linear ion trap (Q-LIT) mass spectrometer, a simultaneous fragmentation and accumulation strategy was developed to improve the sensitivity of the analysis for the low-abundance molecules in complex matrices. Ions were filtered by the quadrupole into the LIT. The precursor ions were fragmented and the product ions were isolated and accumulated in the LIT simultaneously. The fragmentation, isolation and accumulation processes were conducted at the same time. The accumulation time could be controlled to accumulate sufficient product ions. RESULTS: With this strategy, the signal intensity of targeted molecules could be increased by 2-8 times and by increasing the accumulation time, this could be further enhanced. Those interferences induced by isomers and matrices can be reduced by using our method. We further applied our method to the quantification and analysis of biological samples. Tryptic digested peptides of myoglobin (Mb) were successfully detected by our method. CONCLUSIONS: We have established a new method with great advantages in the detection of molecules in complex matrices. The application of this method promises better results in the bioanalytical area, especially for the analysis of substances in complex matrices in the future.

Direct analysis of hydroxylated polycyclic aromatic hydrocarbons in biological samples with complex matrices using polarity-reversed nanoelectrospray ionization.

RATIONALE: Polycyclic aromatic hydrocarbons (PAHs) are a class of environmental contaminants with carcinogenic effect drawing worldwide attention. PAHs can be converted into hydroxylated PAHs (OH-PAHs) through metabolic processes. Thus, they are commonly considered as an important class of biomarkers of PAH exposure. However, direct analysis of related metabolites of these environmental pollutants in biological samples using mass spectrometry is still challenging because of matrix effect and ion suppression during nanoelectrospray ionization (nano-ESI). METHODS: In our previous work, a polarity-reversed nanoelectrospray ionization (PR-nESI) technique was developed for the analysis of biomolecules in complex matrices. In this work, we further optimized PR-nESI for direct and sensitive analysis of OH-PAHs in different samples under severe salt interference in negative polarity. RESULTS: Compared with conventional nano-ESI, the optimized PR-nESI method realized sensitive detection of 1-naphthol in samples with a concentration of salt up to millimolar level. The signal-to-noise ratio (S/N) of OH-PAHs was increased by 1-2 orders of magnitude compared with conventional nano-ESI. Six different OH-PAHs were successfully detected with high S/N ratio using PR-nESI. PR-nESI was further successfully applied in the analysis of OH-PAHs in spiked fetal blood serum, human urine, and single-cell samples. For environmentally exposed subjects, the detections of OH-PAHs in single-cell samples and urines from human smokers were successfully conducted. CONCLUSION: The optimized PR-nESI method was successfully applied for the sensitive analysis of OH-PAHs in complex biological samples with severe salt effects. Based on the present study, PR-nESI can have a promising prospect for the sensitive analysis of other metabolites of environmental pollutants in negative polarity.

Lateral Flow Immunoassay Based on Time-Resolved Fluorescence Microspheres for Rapid and Quantitative Screening CA199 in Human Serum.

Carbohydrate antigen 199 (CA199) is a serum biomarker which has certain value and significance in the diagnosis, prognosis, treatment, and postoperative monitoring of cancer. In this study, a lateral flow immunoassay based on europium (III) polystyrene time-resolved fluorescence microspheres (TRFM-based LFIA), integrated with a portable fluorescence reader, has been successfully establish for rapid and quantitative analysis of CA199 in human serum. Briefly, time-resolved fluorescence microspheres (TRFMs) were conjugated with antibody I (Ab1) against CA199 as detection probes, and antibody II (Ab2) was coated as capture element, and a "TRFMs-Ab1-CA199-Ab2" sandwich format would form when CA199 was detected by the TRFM-based LFIA. Under the optimal parameters, the detection limit of the TRFM-based LFIA for visible quantitation with the help of an ultraviolet light was 4.125 U/mL, which was four times lower than that of LFIA based on gold nanoparticles. Additionally, the fluorescence ratio is well linearly correlated with the CA199 concentration (0.00-66.0 U/mL) and logarithmic concentration (66.0-264.0 U/mL) for quantitative detection. Serum samples from 10 healthy people and 10 liver cancer patients were tested to confirm the performances of the point-of-care application of the TRFM-based LFIA, 20.0 U/mL of CA199 in human serum was defined as the threshold for distinguishing healthy people from liver cancer patients with an accuracy of about 60%. The establishment of TRFM-based LFIA will provide a sensitive, convenient, and efficient technical support for rapid screening of CA199 in cancer diagnosis and prognosis.

[A 10-year retrospective study of pathogens and antimicrobial resistance in neonatal sepsis]. / æ–°ç”Ÿå„¿è´¥è¡€ç—‡ç— åŽŸèŒåŠè€è¯æ€§10年回顾性分析.

OBJECTIVES: To investigate the changes in the pathogen spectrum and antimicrobial resistance over time in neonatal sepsis. METHODS: The medical data were collected from the neonates who were diagnosed with sepsis in the Second Xiangya Hospital of Central South University from January 2010 to December 2019. The incidence rate of sepsis, the pathogen spectrum, and the characteristics of antimicrobial resistance were analyzed. RESULTS: The incidence rate of neonatal sepsis was 4.02% (447/11 111). The top four pathogens detected were coagulase-negative staphylococci (CoNS), Klebsiella pneumoniae, Escherichia coli, and Candida. The incidence rate of sepsis and the pathogen spectrum showed no significant changes over time. Klebsiella pneumoniae was the most frequent pathogen in preterm infants, very low birth weight infants, and small-for-gestational-age infants, accounting for 33.9%, 29.5%, and 42.5%, respectively. CoNS, Klebsiella pneumoniae, and Escherichia coli had a high resistance rate to penicillins and third-generation cephalosporins. CONCLUSIONS: The incidence of neonatal sepsis is high, and the main pathogen is CoNS. The pathogens of neonatal sepsis have a high resistance rate to penicillins and third-generation cephalosporins. It is recommended to enhance the prevention and control of neonatal infection, strengthen the surveillance of pathogens, and further standardize the rational use of antibiotics.

Ammonium Bicarbonate Significantly Accelerates the Microdroplet Reactions of Amines with Carbon Dioxide.

The reactions between amines and carbon dioxide (CO2) are among the most commonly used and important carbon fixation reactions at present. Microdroplets generated by electrospray ionization (ESI) have been proved to increase the conversion ratio (RC) of amines. In this work, we confirmed that the presence of ammonium bicarbonate (NH4HCO3) in ESI microdroplets significantly increased the RC of amines. The RC went up remarkably with the increase in the concentration of NH4HCO3 from 0.5 to 20 mM. The RC of N,N-dibutyl-1,3-propanediamine (DBPA) reached 93.7% under 20 mM NH4HCO3, which was significantly higher than previous reports. The rise in RC became insignificant when the concentration of NH4HCO3 was increased beyond 20 mM. Further investigations were made on the mechanism of the phenomenon. According to the results, it was suggested that NH4HCO3 decomposed into CO2 and formed microbubbles within the microdroplets of ESI. The microbubbles acted as direct internal CO2 sources. The conversion reactions occurred at the liquid-gas interface. The formation of CO2 microbubbles remarkably increased the total area of the interface, thus promoting the conversion reactions. 13C-labeled experiments confirmed that NH4HCO3 acted as an internal CO2 source. Factors that influenced the RC of the reaction were optimized. Pure water was proved to be the optimal solvent. Lower temperature of the mass spectrometer's entrance capillary was beneficial to the stabilization of the product carbamic acids. The sample flow rate of ESI was crucial to the RC. It determined the initial sizes of the microdroplet. Lower flow rates ensured higher RC of amines. The present work implied that NH4HCO3 could be a superior medium for CO2 capture and utilization. It might offer an alternative choice for future CO2 conversion research studies. In addition, our study also provided evidence that NH4HCO3 decomposed and generated microbubbles in the droplets during ESI. Attention should be paid to this when using NH4HCO3 as an additive in mass spectrometry-based analysis.

In Situ Identification and Spatial Mapping of Microplastic Standards in Paramecia by Secondary-Ion Mass Spectrometry Imaging.

Microplastics (MPs) are universally present in the ecosystem and pose great threats to the environment and living organisms. Research studies have shown that small MPs (<50 µm in diameter) are especially toxic and account for more than half of all MPs collected in the Atlantic Ocean. Nevertheless, current methods for the detection and analysis of MPs are incapable of achieving rapid and in situ analysis of small MPs in the biota to ultimately enable the study of their biological effects. In this work, we report a method that allows rapid in situ identification and spatial mapping of small MPs directly from paramecia with high accuracy by acquiring chemical composition information using secondary-ion mass spectrometry (SIMS) imaging. Specifically, six types of common MPs (polymethyl methacrylate, polyvinyl chloride, polypropylene, polyethylene terephthalate, polyglycidyl methacrylate, and polyamide 6) with a diameter of 1-50 µm were simultaneously imaged with high chemical specificity at a spatial resolution of 700 nm. In situ spatial mapping of a group of MPs ingested by paramecia was performed using SIMS fragments specific to the plastic composition with no sample pretreatment, revealing the aggregation of MPs in paramecia after ingestion. Compared with existing methods, one additional advantage of the developed method is that the MPs and the organism can be analyzed in the same experimental workflow to record their fingerprint spectra, acquiring biochemical information to evaluate MP fate, toxicity, and the MP-biota interaction.

Strong Acid Anions Significantly Increasing the Charge State of Proteins during Electrospray Ionization.

Regulation of protein's charge state in electrospray is of great importance to the analysis of proteins. Different methods have been developed so far to increase the charge state of proteins. In this work, we investigated the influence of different anions on the charge state of proteins. Both strong acid anions and weak acid anions were taken into consideration. The results showed that the presence of 5 mM strong acid anions in acidic solutions could significantly increase the charge state of proteins. In comparison, weak acid anions with the same concentration in solution had little impact on the charge state of proteins. The species of the cations in the samples had very limited influence on the charge state. The presence of a certain amount of acid in sample solution was critical to the effect of strong acid anions. Almost no increase of the charge state was observed when no acid was added to the samples. However, remarkable increase of the charge state of myoglobin (Mb) was observed when 0.001% (v/v) acetic acid (HAc) was added to the sample together with 5 mM sodium chloride (NaCl). A higher concentration of acid in samples would further enhance the effect of strong acid anions on the increase of the charge state. Further investigations into the mechanism revealed that the effect of the strong acid anions on the charge state of proteins was based on the unfolding of the protein molecules during electrospray ionization (ESI). The interactions among H+, anions, and protein molecules were so strong that it caused the unfolding of protein molecules and resulted in the increasing of proteins' charge states. The key factor that made strong acid anions and weak acid anions different in the results was the hydrolysis of the weak acid anions in acidic solutions. The present work furthers our understanding about electrospray, as well as the regulation of protein charge state. The presence of strong acid anions in acidic solutions can significantly influence the charge state of proteins in electrospray. Attention should be paid to this when regulating the charge state of proteins.

Plasma metabolites in treatment-requiring retinopathy of prematurity: Potential biomarkers identified by metabolomics.

Retinopathy of prematurity (ROP) is a potentially blinding condition caused by disruption of retinal vascularization and metabolism. This study aims to identify altered metabolites from plasma in patients with treatment-requiring ROP (TR-ROP) compared with controls. An untargeted metabolomics analysis was performed to reveal the metabolomic profiles of the plasma between TR-ROP patients (n = 38) and age-matched infants (n = 23). The Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were conducted to explore the potential signaling pathways of the changed metabolites. Under positive ion mode, a total of 29 metabolites were significantly altered in plasma between TR-ROP patients and controls, and 23 altered metabolites were identified under negative ion mode. KEGG analyses indicated that "protein digestion and absorption" and "aminoacyl-tRNA biosynthesis" were the most enriched pathways of the altered metabolites. These results demonstrated that metabolomic profiles changed in plasma of TR-ROP, and the altered metabolites could be served as potential biomarkers for the diagnosis and prognosis of TR-ROP patients. Besides, the metabolomic profiles might provide clues to discover novel therapeutic strategies in ROP treatment.