Nanomaterial-based miniaturized extraction and preconcentration techniques coupled to matrix-assisted laser desorption/ionization mass spectrometry for assaying biomolecules

Phenolic compounds in surface water: methodology and occurrence in Doce River, Brazil

Phenolic compounds are widely spread in surface water, mainly in developing countries, where sewage and wastewater treatment are still reduced. Thus, this work quantified these pollutants in the Doce River analyzing the associated risk for the environment and human health. This river is in the state of Minas Gerais in Brazil and was recently impacted by the collapse of a mining dam that compromised the resilience of the entire watershed. For that purpose, a methodology for simultaneous identification and quantification of 17 different phenols was developed. It was possible to verify phenolic compounds' occurrence with concentration ranging from 0.13 to 24.16 µg·L^-1. 2-Nitrophenol and bisphenol A appeared in all samples analyzed. The analytical method was processed using solid-phase extraction (SPE) (C₁₈ cartridge), gas chromatography with FID, and mass spectrometry to define the analytes' retention time. For case validation, the selectivity, linearity, detection and quantification limits, sensitivity, precision, accuracy, resolution, matrix effect, and peak quality were assessed. Four different solvents were tested in the recovery-grade trials, which were dichloromethane, methanol, acetonitrile, and ethyl acetate. Among them, methanol had a better performance and was used throughout all analyses. The phenolic compounds had a recovery degree higher than 50% after SPE, regardless of the matrices.

Application of magnetic nanomaterials in electroanalytical methods: A review

Magnetic nanomaterials (MNMs) have gained high attention in different fields of studies due to their ferromagnetic/superparamagnetic properties and their low toxicity and high biocompatibility. MNMs contain magnetic elements such as iron and nickel in metallic, bimetallic, metal oxide, and mixed metal oxide. In electroanalytical methods, MNMs have been applied as sorbents for sample preparation before the electrochemical detection (sorbent role), as the electrode modifier (catalytic role), and the integration of the above two roles (as both sorbent and catalytic agent). In this paper, the application of MNMs in electroanalytical methods have been classified based on the main role of the nanomaterial and discussed separately. Furthermore, catalytic activities of MNMs in electroanalytical methods such as redox electrocatalytic, nanozymes catalytic (peroxidase, catalase activity, oxidase activity, superoxide dismutase activity), catalyst gate, and nanocontainer have been discussed.

Development, validation, comparison, and implementation of a highly efficient and effective method using magnetic solid-phase extraction with hydrophilic-lipophilic-balanced materials for LC-MS/MS analysis of pesticides in seawater

To achieve multi-pesticides residue analysis in seawater, hydrophilic-lipophilic-balanced magnetic particles were designed and fabricated by swelling polymerization of divinyl benzene (DVB) and N-vinyl pyrrolidone (NVP) on the surface of Fe₃O₄@SiO₂ magnetic particles. The ratio of DVB to NVP was adjusted to achieve a proper balance in hydrophilicity and lipophilicity. The obtained magnetic particles were systematically characterized by TEM, SEM, FT-IR and vibrating sample magnetization. Based on the optimized magnetic nanoparticles, a sensitive magnetic solid-phase extraction method was developed for the simultaneous pre-concentration and determination of 96-pesticide residues from large-volume seawater samples prior to being detected by liquid chromatography-tandem mass spectrometry. Recoveries of pesticides in spiked seawater samples (0.001, 0.01, 0.1, 1.0 μg L^-1) ranged from 62% to 112% with RSDs less than 21%. The method limits of detection of 96 pesticides ranged from 0.13 to 0.42 ng L^-1, the method limits of quantification of 96 pesticides ranged from 1.0 to 10 ng L^-1. The method was successfully applied to pesticide residue analysis in water samples from Jiulong River Estuary of China, demonstrating the prospects of this technique as a potential method for the rapid determination of trace levels of multi-pesticide residues in seawater.

Progress of electrospray ionization and rapid evaporative ionization mass spectrometric techniques for the broad-range identification of microorganisms

Electrospray ionization and rapid evaporative ionization mass spectrometric techniques have attracted much attention in the identification of microorganisms, and in the diagnosis of bacterial infections from clinical samples.

Mass Spectrometry Genotyping of Human Papillomavirus Based on High-Efficiency Selective Enrichment of Nanoparticles

This work developed a novel spermine-modified nanodiamonds (SP-NDs)-based method to selectively enrich oligonucleotides for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) of human papillomavirus (HPV) virus. Our results showed that SP-NDs can effectively extract and enrich DNA oligonucleotides from sodium dodecyl sulfonate and urea solution. In addition, SP-NDs can also selectively extract oligonucleotides from enzymes digestion products of polymerase chain reaction-restriction fragment mass polymorphism (PCR-RFMP) of HPV virus. Then, the extract can be detected by MALDI-TOF MS directly without further purification. According to the MS results, the HPV genotyping can be achieved. More importantly, with SP-NDs extraction, clinical samples infected with HPV genotype 16 and 18 can be identified. The described method shows great advantages of simplicity, high selectivity, and good reliability in real clinical samples. Due to our methods improvement on DNA enrichment, extraction and purification, the PCR-based MALDI-TOF MS for the analysis of oligonucleotides maybe become more rapid, sensitive, and high-throughput, is promising for analysis for DNA methylation, single-nucleotide polymorphisms, and other virus typing.

Development of an efficient and sensitive analytical method for the determination of copper at trace levels by slotted quartz tube atomic absorption spectrometry after vortex-assisted dispersive liquid-liquid microextraction in biota and water samples using a novel ligand

This study describes the determination of trace levels of copper by slotted quartz tube atomic absorption spectrometry after dispersive liquid-liquid microextraction. A ligand synthesized from the reaction of salicylaldehyde and 1-naphthylamine was used to form coordinate copper complex prior to extraction. All parameters that influence the output of complex formation, extraction, and instrumental measurement were optimized to enhance the absorbance signal of copper. Under the optimum conditions, about 104-fold enhancement in sensitivity was recorded over the conventional flame atomic absorption spectrometer, corresponding to a 0.51 ng/mL detection limit. The percent relative standard deviation calculated for the lowest concentration (4.8%) indicated high precision for the experimental procedure. Accuracy and applicability of the optimum method were determined by performing spiked recovery tests on urine, lake water, and mineral water samples. Satisfactory recovery results were obtained between 82.2 and 106.3% at four different concentrations. Matrix matching method was also performed to increase the accuracy of quantification, and the percent recovery calculated for 175 ng/mL was 105.14%.

Structural Characterization of Biofunctionalized Gold Nanoparticles by Ultrahigh-Resolution Mass Spectrometry

Biofunctionalized gold nanoparticles (AuNPs) enable innovative translational research and development in biomedicine. Biomolecules such as peptides, proteins, lipids, and carbohydrates can be assembled onto AuNPs to yield nanomaterials with unique properties for applications in imaging, photothermal therapy, vaccination strategies, and drug delivery. The characterization of functionalized AuNPs still remains an analytical challenge that normally requires the combination of multiple techniques. Laser desorption/ionization (LDI) and matrix-assisted LDI (MALDI) have been applied successfully in combination with time-of-flight (TOF) mass spectrometry (MS) for the analysis of the surface chemistry of AuNPs functionalized with synthetic ligands, however only for ligands with a molecular mass limited to 1000 Da. TOF-MS-based approaches in addition exhibit limited performance in terms of mass resolution and MS/MS possibilities. To overcome these limitations, we designed an approach for the analysis of AuNPs based on ultrahigh resolution Fourier transform ion cyclotron resonance (FTICR) MS and a combination of LDI and MALDI. To illustrate the performance of the method, we present a comprehensive characterization of the surface chemistry of AuNPs conjugated via a thiol-ending linker to either the ovalbumin peptide (OVA 323-339), the Lewis X antigen (Galβ1-4[Fucα1-3]GlcNAcβ1) trisaccharide, the tetramannoside Manα1-2Manα1-2Manα1-3Manα1, or a mixture of both carbohydrates. Collision-induced dissociation (CID) was used to characterize the structure of pseudomolecular ions generated by LDI/MALDI in-depth. These included [M + H]⁺ and [M + Na]⁺, and importantly also [M + Au]⁺ and [M + 2Au-H]⁺ ions. This first observation of gold-containing pseudomolecular ions provides direct evidence for the Au-conjugation of ligands. In addition, we show the applicability of the method to monitor proteolytic cleavage of peptides that are conjugated to the AuNP surface. The presented LDI/MALDI-FTICR-MS and MS/MS approach will be applicable to the characterization of a wide range of functionalized AuNPs.

The Development of Novel Nanodiamond Based MALDI Matrices for the Analysis of Small Organic Pharmaceuticals

The utility of novel functionalized nanodiamonds (NDs) as matrices for matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) is described herein. MALDI-MS analysis of small organic compounds (<1000 Da) is typically complex because of interferences from numerous cluster ions formed when using conventional matrices. To expand the use of MALDI for the analysis of small molecules, novel matrices were designed by covalently linking conventional matrices (or a lysine moiety) to detonated NDs. Four new functionalized NDs were evaluated for their ionization capabilities using five pharmaceuticals with varying molecular structures. Two ND matrices were able to ionize all tested pharmaceuticals in the negative ion mode, producing the deprotonated ions [M - H](-). Ion intensity for target analytes was generally strong with enhanced signal-to-noise ratios compared with conventional matrices. The negative ion mode is of great importance for biological samples as interference from endogenous compounds is inherently minimized in the negative ion mode. Since the molecular structures of the tested pharmaceuticals did not suggest that negative ion mode would be preferable, this result magnifies the importance of these findings. On the other hand, conventional matrices primarily facilitated the ionization as expected in the positive ion mode, producing either the protonated molecules [M + H](+) or cationic adducts (typically producing complex spectra with numerous adduct peaks). The data presented in this study suggests that these matrices may offer advantages for the analysis of low molecular weight pharmaceuticals/metabolites. Graphical Abstract ᅟ.

Targeting human pathogenic bacteria by siderophores: A proteomics review

Human bacterial infections are still a major public health problem throughout the world. Therefore it is fundamental to understand how pathogenic bacteria interact with their human host and to develop more advanced drugs or vaccines in response to the increasing bacterial resistance. Since iron is essential to bacterial survival and growth inside the host tissues, these microorganisms have developed highly efficient iron-acquisition systems; the most common one involves the secretion of iron chelators into the extracellular environment, known as siderophores, and the corresponding siderophore-membrane receptors or transporters responsible for the iron uptake. In the past few decades, several biochemical methods and genetic screens have been employed to track down and identify these iron-scavenging molecules. However, compared with the previous "static" approaches, proteomic identification is revealing far more molecules through full protein mapping and becoming more rapid and selective, leading the scientific and medical community to consider standardizing proteomic tools for clinical biomarker detection of bacterial infectious diseases. In this review, we focus on human pathogenic Gram-negative bacteria and discuss the importance of siderophores in their virulence and the available proteomic strategies to identify siderophore-related proteins and their expression level under different growth conditions. The promising use of siderophore antibiotics to overcome bacterial resistance and the future of proteomics in the routine clinical care are also mentioned.

SIGNIFICANCE

Proteomic strategies to identify siderophore-related proteins and their expression level can be helpful to control and/or find a cure of infectious deseases especially if related with multidrug resistance. Siderophores are low-molecular-weight compounds produced by bacteria which can become clinical biomarkers and/or antibiotics used mainly in "Trojan horse" type strategies. Due to the above mention we think that the promising use of siderophore to overcome bacterial resistance and the future of proteomics in the routine clinical care is a hot topic that should be discussed.

Liquid crystals as optical amplifiers for bacterial detection

Interactions of bacteria with target molecules (e.g. antibiotics) or other microorganisms are of growing interest. The first barrier for targeting gram-negative bacteria is layer of a Lipopolysaccharides (LPS). Liquid crystal (LC) based sensors covered with LPS monolayers, as presented in this study, offer a simple model to study and make use of this type of interface for detection and screening. This work describes in detail the production and application of such sensors based on three different LPS that have been investigated regarding their potential to serve as sensing layer to detect bacteria. The LPS O127:B8 in combination with a LC based sensor was identified to be most useful as biomimetic sensing surface. This LPS/LC combination interacts with three different bacteria species, one gram-positive and two gram-negative species, allowing the detection of bacterial presence regardless from their viability. It could be shown that even very low bacterial cell numbers (minimum 500 cell ml(-1)) could be detected within minutes (maximum 15 min). The readout mechanism is the adsorption of bacterial entities on surface bond LPS molecules with the LC serving as an optical amplifier.

A systematic investigation on the interaction of l-cysteine functionalised Mn3O4 nanoparticles with lysozyme

Interactions of cysteine capped Mn₃O₄ nanoparticles with HEWL.

Mg2+ ion as a tuner for colorimetric sensing of glyphosate with improved sensitivity via the aggregation of 2-mercapto-5-nitrobenzimidazole capped silver nanoparticles

The sensitivity of MNBZ-Ag NPs was greatly improved by integrating Mg²⁺ ion as trigger that can capture the glyphosate at nanomolar concentration with high selectivity.

Trypsin immobilization in ordered porous polymer membranes for effective protein digestion

Fast and effective protein digestion is a vital process for mass spectrometry (MS) based protein analysis. This study introduces a porous polymer membrane enzyme reactor (PPMER) coupled to nanoflow liquid chromatography-tandem MS (nLC-ESI-MS/MS) for on-line digestion and analysis of proteins. Poly (styrene-co-maleic anhydride) (PS-co-MAn) was fabricated by the breath figure method to make a porous polymer membrane in which the MAn group was covalently bound to enzyme. Based on this strategy, microscale PPMER (μPPMER) was constructed for on-line connection with the nLC-ESI-MS/MS system. Its capability for enzymatic digestion with bovine serum albumin (BSA) was evaluated with varied digestion periods. The on-line proteolysis of BSA and subsequent analysis with μPPMER-nLC-ESI-MS/MS revealed that peptide sequence coverage increased from 10.3% (digestion time 10 min) to 89.1% (digestion time 30 min). μPPMER can efficiently digest proteins due to the microscopic confinement effect, showing its potential application in fast protein identification and protease immobilization. Applications of on-line digestion using μPPMER with human plasma and urinary proteome samples showed that the developed on-line method yielded equivalent or better performance in protein coverage and identified more membrane proteins than the in-solution method. This may be due to easy accommodation of hydrophobic membrane proteins within membrane pores.

Analytical applications of nanoparticles in MALDI-MS for bioanalysis

Recently, the rapid development of nanotechnology has enabled the analytical community to integrate processes with MALDI-MS for the analysis of various biomolecules. This article presents the recent progress on nanomaterials as extracting probes in single-drop microextraction, in liquid-liquid microextraction and as affinity probes for the enrichment of trace level biomolecules prior to their identification by MALDI-MS.

Simultaneous colorimetric detection of four drugs in their pharmaceutical formulations using unmodified gold nanoparticles as a probe

Schematic representation for the aggregation of unmodified Au NPs induced by four drugs (venlafaxine, imipramine, amlodipine, and alfuzosin).

Synthesis, characterization and bifunctional applications of bidentate silver nanoparticle assisted single drop microextraction as a highly sensitive preconcentrating probe for protein analysis

Synthesis, characterization and bifunctional applications of silver nanoparticles with two different surface capping reagents are reported.