Novel Small Molecule Matrix Screening for Simultaneous MALDI Mass Spectrometry Imaging of Multiple Lipids and Phytohormones.

Most of the traditional matrices cannot simultaneously image multiple lipids and phytohormones, so screening and discovery of novel matrices stand as essential approaches for broadening the application scope of matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). In this work, 12 organic small molecule compounds were comprehensively screened and investigated as potential MALDI matrices for simultaneous imaging analysis of various lipids and phytohormones. In the positive ionization mode, p-nitroaniline, m-nitroaniline, and 2-aminoterephthalic acid displayed good performance for the highly sensitive detection of lysophosphatidylcholines (LPCs), phosphatidylcholines (PCs), and triacylglycerols (TGs). Furthermore, p-nitroaniline possessed excellent characteristics of strong ultraviolet absorption and homogeneous cocrystallization, making it a desirable matrix for MALDI-MSI analysis of eight plant hormones. Compared with conventional matrices (2,5-dihydroxybenzoic acid (DHB), α-cyano-4-hydroxycinnamic acid (CHCA), and 9-aminoacridine (9-AA), the use of p-nitroaniline resulted in higher ionization efficiency, superior sensitivity, and clearer imaging images in dual polarity mode. Our research offers valuable guidance and new ideas for future endeavors in matrix screening.

Transition metal composites for selective analysis of vitamin B2 in rice by ultrahigh-performance liquid chromatography-tandem mass spectrometry.

A novel amino-functionalized zinc ferrite nanoparticles/MXene (ZnFe2O4-NH2/MXene composite which consist of ZnFe2O4-NH2 and single/few layers MXene was designed and synthesized as an efficient extractant for analysis of vitamin B2 in rice first combined with ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). As a result, the single/few layer MXene was tightly attached to the spherical ZnFe2O4-NH2 nanoparticles by electrostatic self-assembly interaction, which present large specific surface area and fast mass transfer rate. The relevant experimental parameters, including the pH of the solution, extraction time, adsorbent amount, desorption solvent, desorption solvent volume and desorption time were investigated and optimized. Under optimum conditions, the ZnFe2O4-NH2/MXene composite exhibited excellent selectivity and adsorption capacity for vitamin B2 through hydrogen bonding interactions and the metal-π complexation interaction. The adsorption kinetics, isotherms, and thermodynamic studies were systemically investigated to evaluate the adsorption mechanism and characteristics, which ascribed to chemical adsorption, monolayer adsorption and a spontaneous endothermic process. Furthermore, the performance of the proved method was validated with the good linear correlation coefficient (r = 0.999), low limit of detection (0.86 ng·mL-1) and the limit of quantification (2.98 ng·mL-1), satisfactory recoveries (81.7-102.5%) and reasonable accuracy (RSD<7.8%). The theoretical and technological underpinning for investigating the kinship amongst vitamin alterations and the degree of rice storage was set using this suggested approach to assess vitamin B2 in rice from various years.

Tracking Spatial Distribution Alterations of Multiple Endogenous Molecules during Lentil Germination by MALDI Mass Spectrometry Imaging.

Exploring the spatial distribution alterations of metabolites during lentil germination is essential to reveal the nutritional value, physiological function, and metabolic pathway in lentils. Hence, an effective matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) method was established for the first time to visualize the spatial localization changes of 53 metabolites in lentils during germination for 12-72 h. The results of MALDI-MSI analysis showed that phosphatidylinositols, phosphatidylethanolamines, phosphatidylglycerols, and phosphatidic acids were mainly located in the cotyledons of lentils throughout the germination process, while triacylglycerols, phosphatidylcholines, diacylglycerols, amino acids, choline, and spermine spread throughout the lentil tissue at the initial stage of germination and gradually presented obvious distribution characteristics in the radicle with increasing germination time. Heat map analysis was used to visualize the correlations between lipid content changes and germination time, which supported the use of germinated lentils as nutraceutical or functional food.

A reliable and effective sample preparation protocol of MALDI-TOF-MSI for lipids imaging analysis in hard and dry cereals.

A superior sectioning sample preparation protocol is the basic guarantee for maintaining data reliability in MALDI-TOF-MSI analysis. Despite significant advances in sample preparation, visualization of lipids in hard and dry cereals remains difficult due to their inherent physicochemical properties. Thus, a cryosections preparation method was designed via poly-l-lysine soaking, conductive tape adhesion and embedding medium fixation, which preserved the spatial integrity of lipids in cereals without causing analyte delocalization and obvious background interference. Higher signal intensity and clearer imaging of lipids in rice, wheat and barley (Qingke) were obtained using the established sample preparation method. Moreover, the spatial distribution of lipids was visualized in rice with different storage years, which found that the phosphatidylinositols (PIs) and phosphatidylglycerols (PGs) could be used for evaluation of rice aging degree. Our study provided molecular level guidance for further discussion of rice aging mechanism, rice quality evaluation and safety monitoring.

Gold bipyramids molecularly imprinted gel colorimetric device for whole blood cholesterol analysis.

Simple and disposable monitoring of blood is usually the best solution for early clinical diagnosis and home self-inspection of the chronic patients. Herein, a simple point-of-care (POC) device which called molecularly imprinted membrane modified gel colorimetric device (MIMGCD) was prepared for whole blood cholesterol colorimetric detection at the first time. The convenient detection principle of this device rely on molecularly imprinted membranes for specifically separating cholesterol from whole blood firstly, following the gold bipyramids (GBPs) agarose gel system is react with the cholesterol oxidation to product hydrogen peroxide (H2O2), and the cholesterol will be quantified based on the color change. Under optimal conditions, the analytical performance of the proposed device yielded a linear range of 315.8-6000.0 µM and detection limit of 94.7 µM with 6.89% RSD for cholesterol, which can meet the needs of the detection of normal cholesterol content in the human body. Compared with the traditional whole blood detection methods, no complex sample preparation steps or precision instruments are required, endowing MIMGCD with the merits of easy to operate and low-cost. In addition, the multicolor variation of GBPs in the device allow a colorimetric card-like detection mechanism, which can be used for home self-inspection. This device has the potential to be utilized in clinical and home POC testing application for whole blood biomolecule analysis, thereby facilitating the whole blood screening and long-term monitoring in non-specialized laboratory infrastructure.

Three-dimensional tree-like branched TiO2 nanorods for the highly selective enrichment and determination of lead.

Branched titanium dioxide nanorods (B-TiO2 NRs) grown on fluorine-doped tin oxide glass (FTO) were developed, which can be used as a solid-phase extractant for preconcentration and determination of trace Pb(II) combined with inductively coupled plasma optical emission spectrometry (ICP-OES). The B-TiO2 NR-based glass substrate displayed excellent adsorptive selectivity and capacity for Pb(II); the maximum adsorption capacity was found to be 168.4 mg⋅g-1 PB(II) at pH = 5.0. It proved that the primary extraction mechanism was attributed to soft acid/soft base interactions to form complexes for chemisorption. Investigating the adsorption kinetics and isotherms indicated that the pseudo-second-order and Langmuir models can better describe Pb(II) adsorption on the B-TiO2 NRs. The proposed method presented good linearity from 0.01 to 5 mg⋅L-1 with a correlation coefficient (R2) of 0.9989 and a low limit of detection (LOD) of 2.2 µg⋅L-1 for Pb(II) under optimal conditions. The method was successfully applied to Pb(II) determination in foodstuffs with desirable recoveries from 93.18 to 108.1% and good precision with an RSD of less than 12.2%. This work provides a new strategy for selective extraction and determination of Pb(II) in complicated matrix samples.

Polyaniline spinel particles with ultrahigh-performance liquid chromatography tandem mass spectrometry for rapid vitamin B9 determination in rice.

Rice is an important crop that provides energy and nutrients to humans, which undergoes the aging process, the quality decline is related to the exogenous storage conditions and the change of own enzyme activity. However, due to the complex composition of rice and serious matrix interference, the ageing identification of rice is still challenging. Hence, a novel spinel particles ZnFe2O4@PANI was designed and synthesized for adsorption and determination of vitamin B9, which can be used to distinguish rice in different years and analyze the degree of aging. The ZnFe2O4@PANI showed large specific surface area and fast mass transfer rate with good linear correlation coefficient (R2 = 0.9965), satisfactory recoveries (85.1%-99.9%) and relative standard deviations (RSD, 9.3%). Moreover, the π-π electron-donor-acceptor (EDA) and intermolecular hydrogen-bonding interactions of polyaniline coating provided selective adsorption on vitamin B9. Adsorption thermodynamics study suggested that the adsorption reactions were spontaneous, endothermic and thermodynamically favorable. Finally, ZnFe2O4@PANI was used to evaluate vitamin B9 in rice from different years, which laid a theoretical foundation for exploring the relationship between vitamin changes and the aging degree of the rice.

Colorimetric detection of human alpha-2-macroglobulin by janus imprinted nanoparticles constructed dual molecular imprinting immunosandwich strategy.

Simple and rapid detection of disease-related bio-markers are significant for early clinical diagnosis and can potentially improve the survival rate. However, establishing a high-specificity colorimetric detection method for bio-markers are still challenges due to their inevitable natural antibody used or enzymatic labeling. Herein, a cost-efficient and easy-to-use approach, which called dual molecular imprinting immunosandwich colorimetric strategy (DMI-ICS) was constructed for detection alpha-2-macroglobulin (α2MG) by janus imprinted nanoparticles. The unique detection principle was contained with two mimic antibody parts, the first part was α2MG glass slides molecularly imprinted material (GS-MIP) as a "Separation antibody", which can specifically rapid separate the protein in the complex sample; Another part was asymmetrically modified janus molecularly imprinted gold nanoparticles nanozyme (J-GNPs-MIP) as a "Detection antibody", which has the properties of specific recognition and catalytic substrate color performance at the same time. The concentration of α2MG can be determined by the substrate color changes and observed with naked eyes. Under the optimized conditions, the DMI-ICS had a great performance and offering lower relative standard deviation (RSD, 7.69%), good linear range (0.297-130 µg/mL, R2 = 0.994), high imprinting factor (IF: 3.74) with lower detection limit (0.089 µg/mL). This strategy provides an easy operation and low cost signal readout method for direct detection and separation of α2MG in human serum samples, which is a versatile tool for point-of-care diagnosis, while also offering a new perspective on antibody simulation technology, multifunctional antibody preparation and contribute to detection of disease-related bio-marker in nonspecialized laboratory infrastructure.

Visualizing the spatial distribution of endogenous molecules in wolfberry fruit at different development stages by matrix-assisted laser desorption/ionization mass spectrometry imaging.

Wolfberry fruit has been attracting attention for centuries in Asian countries as a traditional herbal medicine and valuable nourishing tonic. Revealing the spatial distribution changes of important endogenous molecules during plant development is of great significance for investigating the physiological roles, nutritional and potential functional values of phytochemicals in wolfberry fruit. However, their spatial distribution information during fruit development has not been extensively explored due to the lack of efficient analytical techniques. In this work, matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) was performed to visualize the spatial distribution of the endogenous molecules during fruit development. From the mass spectrum imaging, the choline, betaine and citric acid were distributed evenly throughout the entire fruit at all development stages. The hexose was distributed in the endocarp and flesh tissue, while sucrose was located in the seeds. Additionally, several phenolic acids and flavonoids were accumulated in the exocarp during fruit development, which indicated that they seemingly played protective roles in wolfberry fruit growth progress against abiotic and biotic stress. From the collected data, we found that the signal intensities of citric acid were decreased, while choline, betaine, hexose and sucrose were increased with fruit development. These results indicate that MALDI-MSI may become a favorable tool for studying of the spatial distribution and effective use of endogenous molecules, which provide a simple and intuitive way for authenticity identification, classification of drug food homologous foods and further understanding the physiological roles of endogenous molecules.

Spatial distribution analysis of phospholipids in rice by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry imaging.

Phospholipids are one of the main nutrients in rice, which have a positive effect on cancer, coronary heart disease and inflammation. However, phospholipids will become small molecular volatile substances during the aging process of rice, resulting in change the flavor of rice. Therefore, mapping the concentration and the spatial distribution of phospholipids in rice are of tremendous significance in its function research. In this work, we established a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) imaging method for the spatial distribution analysis of phospholipids in rice. A total of 12 phospholipid compounds were found in the range of m/z 500-1000 through a series of conditions optimization. According to the results, lysophosphatidylcholine (LPC) species spread throughout the rice tissue sections and phosphatidylcholine (PC) species distributed in the bran and embryo (particularly in the scutellum). We also compared the signal intensities of phospholipids in different parts of white rice and brown rice by region of interest (ROI) analysis, which showed the relative content of PC species was higher in the embryo and gradually decreased until disappeared with the increase of processing degree during the processing of brown rice to white rice. The PC species on the surface of rice could be used as an important indicator to identify the processing degree of rice. Our work not only establish a MALDI-TOF-MS imaging method for spatial distribution analysis of rice, but also provide the necessary reference for ensuring food security, improving the eating quality of rice and the health benefits of consumers.

Magnetic fluorescent molecularly imprinted nanoparticles for detection and separation of transferrin in human serum.

Transferrin (TrF) is an important glycoprotein and disease biomarker that controls iron ion balance in the human body. Isolation and detection of TrF have important implication for the early detection of disease. Thus, a magnetic fluorescent molecularly imprinted nanoparticles (FMINPs) was prepared for extraction and fluorescence detection of TrF. The FMINPs was prepared with two steps, the first step was the synthesis of magnetic TrF imprinted nanoparticle and the second step was introducing a near-infrared fluorescent compound (CyA) on the imprinted nanoparticles, which has a strong near infrared fluorescence emission at 730 nm while excitation at 690 nm and a large fluorescence signal quenching after adsorption of TrF. The concentration of TrF can be determined by the change of the fluorescence signal. FT-IR, TEM and fluorescence spectrophotometer were used to verify the successful preparation and the fluorescence performance of the FMINPs. Under the optimized experimental conditions, the prepared FMINPs had a great fluorescence performance, offering the lower relative standard deviation (7.7%), good analytical range (0.025-0.175 mg/mL, R2 =0.998) and lower detection limit (0.0075 mg/mL) for TrF. This method provides a new solution for the direct detection and separation of TrF in human serum samples.

Attenuation of Thrombosis by Crude Rice (Oryza sativa) Bran Policosanol Extract: Ex Vivo Platelet Aggregation and Serum Levels of Arachidonic Acid Metabolites.

Background. Vascular occlusion or thrombosis was often attributed to uncontrolled platelet activation. Influence of sugarcane policosanol extract on platelet was reported but little was known of rice bran policosanol, particularly its mechanisms of actions on platelet activities. Objective. Antiplatelet mechanisms of rice bran policosanol extract (RBE) were studied using hyperlipidemic Sprague Dawley rats. Ex vivo platelet aggregation, platelet count (PC), bleeding time (BT), and coagulation time were assayed. Serum eicosanoids and other aggregation-related metabolites levels were quantified. Design. Rats were divided into 6 groups for comparisons (vehicle control Tween 20/H2O, high dose policosanol 500 mg/kg, middle dose policosanol 250 mg/kg, low dose policosanol 100 mg/kg, and positive control aspirin 30 mg/kg). Results. Low dose 100 mg/kg of RBE inhibited aggregation by 42.32 ± 4.31% and this was comparable with the effect of 30 mg/kg aspirin, 43.91 ± 5.27%. Results showed that there were no significant differences in PC, BT, and coagulation time among various groups after RBE treatment. Serum thromboxane A2 was attenuated while prostacyclin level increased upon RBE treatment. Conclusions. RBE reduced ex vivo ADP-induced platelet aggregation without giving adverse effects. No changes in full blood count suggested that rice bran policosanol did not disturb biological blood cell production and destruction yet it reduced aggregation through different mechanisms.

Modulation of platelet functions by crude rice (Oryza sativa) bran policosanol extract.

BACKGROUND: Rice bran is bioactive-rich and has proven health benefits for humans. Moreover, its source, the brown rice has antioxidant, hypolipidemic and other functional properties that are increasingly making it a nutritional staple especially in Asian countries. This study investigated the antiplatelet aggregation mechanisms of crude hexane/methanolic rice bran extract, in which policosanol was the targeted bioactive. Platelets play a vital role in pathogenesis of atherosclerosis and cardiovascular diseases, and their increased activities could potentially cause arterial thrombus formation or severe bleeding disorders. Thus, in this study, platelet aggregation and adhesion of platelets to major components of basal lamina were examined in vitro. In addition, cellular protein secretion was quantified as a measurement of platelet activation. METHODS: Adenosine diphosphate (ADP), collagen, and arachidonic acid (AA)-induced aggregation were studied using the microtiter technique. Rat platelets were pre-treated with various concentrations of policosanol extract, and the adhesion of platelets onto collagen- and laminin-coated surface (extracellular matrix) was studied using the acid phosphatase assay. The effect of crude policosanol extract on released proteins from activated platelets was measured using modified Lowry determination method. RESULTS: Rice bran policosanol extract significantly inhibited in vitro platelet aggregation induced by different agonists in a dose dependent manner. The IC50 of ADP-, collagen-, and AA-induced platelet aggregation were 533.37 ± 112.16, 635.94 ± 78.45 and 693.86 ± 70.57 µg/mL, respectively. The present study showed that crude rice bran policosanol extract significantly inhibited platelet adhesion to collagen in a dose dependent manner. Conversely, at a low concentration of 15.625 µg/mL, the extract significantly inhibited platelet adhesion to laminin stimulated by different platelet agonists. In addition to the alteration of cell adhesive properties, cellular protein secretion of the treated platelets towards different stimulants were decreased upon crude extract treatment. CONCLUSION: Our results showed that crude rice bran policosanol extract could inhibit in vitro platelet adhesion, aggregation and secretion upon activation using agonists. These findings serve as a scientific platform to further explore alternative therapies in cardiovascular diseases related to platelet malfunction.