A preliminary report on the exploration of salivary bacterial diversity by the multiplex SNaPshot assay

Salivary bacterial community composition is associated with the host's internal and environmental factors, which have potential applications in forensic practice. The 16S rRNA gene sequencing is the most commonly used strategy for detecting salivary bacterial diversity; however, its platforms are not compatible with capillary electrophoresis (CE) platforms commonly used for forensic applications. Therefore, we attempted to detect the salivary bacterial diversity using a single nucleotide polymorphism (SNP) assay. Salivary bacterial diversity varies among diverse geographic locations, making it a potential supplementary biomarker for forensic geographic sourcing. To evaluate the performance of the multiplex SNaPshot assay, saliva samples from three geographic locations in China were analyzed using the multiplex SNaPshot assay and 16S rRNA gene sequencing. We screened SNPs from two high-relative-abundance salivary genera (Streptococcus and Veillonella) to construct a multiplex SNaPshot system that can be used on the CE platform. The stability and sensitivity of the multiplex SNaPshot system were also tested. A random forest classification model was used to classify samples from different regions to explore the ability of salivary bacteria to discriminate between geographic sources. Six bacterial SNPs were screened and a multiplex SNaPshot system was constructed. The stability results showed that the typing of salivary stains that were placed indoors for different days was not affected in this study. Two-thirds of mocked salivary stain samples showed more than 90% of typing results obtained for salivary stain samples with an input of 0.1 µl saliva. The results of principal coordinate analysis based on salivary bacterial diversity showed significant differences between samples from the three different geographic locations. The accuracy of the random forest classification was 66.67% based on the multiplex SNaPshot assay and 83.33% based on the 16S rRNA gene sequencing. In conclusion, this is the first attempt to detect salivary bacterial diversity using a multiplex SNaPshot bacterial SNP assay. The geographic difference in human salivary bacterial community composition was significant, as revealed by the multiplex SNaPshot assay; however, its performance in discriminating geographic sources was lower than that of 16S rRNA gene sequencing. This strategy based on bacterial SNP loci may favor the detection of human bacterial diversity in common forensic laboratories but requires further exploration in larger sample sizes and more bacterial SNP loci.

Study of metalation of thioredoxin by gold(I) therapeutic compounds using combined liquid chromatography/capillary electrophoresis with inductively coupled plasma/electrospray MS/MS detection

The reactivity of thioredoxin (Trx1) with the Au(I) drug auranofin (AF) and two therapeutic N-heterocyclic carbene (NHC)2-Au(I) complexes (bis [1-methyl-3-acridineimidazolin-2-ylidene]gold(I) tetrafluoroborate (Au3BC) and [1,3-diethyl-4,5-bis(4methoxyphenyl)imidazol-2-ylidene]gold(I) (Au4BC)) was investigated. Direct infusion (DI) electrospray ionization (ESI) mass spectrometry (MS) allowed information on the structure, stoichiometry, and kinetics of formation of Trx-Au adducts. The fragmentation of the formed adducts in the gas phase gave insights into the exact Au binding site within the protein, demonstrating the preference for Trx1 Cys32 or Cys35 of AF or the (NHC)2-Au(I) complex Au3BC, respectively. Reversed-phase HPLC suffered from the difficulty of elution of gold compounds, did not preserve the formed metal-protein adducts, and favored the loss of ligands (phosphine or NHC) from Au(I). These limitations were eliminated by capillary electrophoresis (CE) which enabled the separation of the gold compounds, Trx1, and the formed adducts. The ICP-MS/MS detection allowed the simultaneous quantitative monitoring of the gold and sulfur isotopes and the determination of the metallation extent of the protein. The hyphenation of the mentioned techniques was used for the analysis of Trx1-Au adducts for the first time.

Development of a novel five-dye panel for human identification insertion/deletion (INDEL) polymorphisms

DNA analysis of forensic case samples relies on short tandem repeats (STRs), a key component of the combined DNA index system (CODIS) used to identify individuals. However, limitations arise when dealing with challenging samples, prompting the exploration of alternative markers such as single nucleotide polymorphisms (SNPs) and insertion/deletion (INDELs) polymorphisms. Unlike SNPs, INDELs can be differentiated easily by size, making them compatible with electrophoresis methods. It is possible to design small INDEL amplicons (<200 bp) to enhance recovery from degraded samples. To this end, a set of INDEL Human Identification Markers (HID) was curated from the 1000 Genomes Project, employing criteria including a fixation index (FST) ≤ 0.06, minor allele frequency (MAF) >0.2, and high allele frequency divergence. A panel of 33 INDEL-HIDs was optimized and validated following the Scientific Working Group on DNA Analysis Methods (SWGDAM) guidelines, utilizing a five-dye multiplex electrophoresis system. A small sample set (n = 79 unrelated individuals) was genotyped to assess the assay's performance. The validation studies exhibited reproducibility, inhibition tolerance, ability to detect a two-person mixture from a 4:1 to 1:6 ratio, robustness with challenging samples, and sensitivity down to 125 pg of DNA. In summary, the 33-loci INDEL-HID panel exhibited robust recovery with low-template and degraded samples and proved effective for individualization within a small sample set.

Machine learning evaluation for identification of M-proteins in human serum

Serum electrophoresis (SPEP) is a method used to analyze the distribution of the most important proteins in the blood. The major clinical question is the presence of monoclonal fraction(s) of antibodies (M-protein/paraprotein), which is essential for the diagnosis and follow-up of hematological diseases, such as multiple myeloma. Recent studies have shown that machine learning can be used to assess protein electrophoresis by, for example, examining protein glycan patterns to follow up tumor surgery. In this study we compared 26 different decision tree algorithms to identify the presence of M-proteins in human serum by using numerical data from serum protein capillary electrophoresis. For the automated detection and clustering of data, we used an anonymized data set consisting of 67,073 samples. We found five methods with superior ability to detect M-proteins: Extra Trees (ET), Random Forest (RF), Histogram Grading Boosting Regressor (HGBR), Light Gradient Boosting Method (LGBM), and Extreme Gradient Boosting (XGB). Additionally, we implemented a game theoretic approach to disclose which features in the data set that were indicative of the resulting M-protein diagnosis. The results verified the gamma globulin fraction and part of the beta globulin fraction as the most important features of the electrophoresis analysis, thereby further strengthening the reliability of our approach. Finally, we tested the algorithms for classifying the M-protein isotypes, where ET and XGB showed the best performance out of the five algorithms tested. Our results show that serum capillary electrophoresis combined with decision tree algorithms have great potential in the application of rapid and accurate identification of M-proteins. Moreover, these methods would be applicable for a variety of blood analyses, such as hemoglobinopathies, indicating a wide-range diagnostic use. However, for M-protein isotype classification, combining machine learning solutions for numerical data from capillary electrophoresis with gel electrophoresis image data would be most advantageous.

Developing DPYD Genotyping Method for Personalized Fluoropyrimidines Therapy

BACKGROUND

Fluoropyrimidine drugs are widely used in chemotherapy to treat solid tumors. However, severe toxicity has been reported in 10% to 40% of patients. The DPYD gene encodes the rate-limiting enzyme dihydropyrimidine dehydrogenase responsible for fluoropyrimidine catabolism. The DPYD variants resulting in decreased or no enzyme activity are associated with increased risk of fluoropyrimidine toxicity. This study aims to develop a pharmacogenetic test for screening DPYD variants to guide fluoropyrimidine therapy.

METHODS

A multiplex allele-specific polymerase chain reaction (AS-PCR) assay, followed by capillary electrophoresis, was developed to detect 5 common DPYD variants (c.557A > G, c.1129-5923C > G, c.1679T > G, c.1905 + 1G > A, and c.2846A > T). Deidentified population samples were used for screening positive controls and optimizing assay conditions. Proficiency testing samples with known genotypes were analyzed for test validation. All variants detected were confirmed by Sanger sequencing.

RESULTS

From the deidentified population samples, 5 samples were heterozygous for c.557A > G, 2 samples were heterozygous for c.1129-5923C > G (HapB3), and 1 sample was heterozygous for c.2846A > T. The 20 proficiency samples matched with their assigned genotypes, including 13 wild-type samples, 3 samples heterozygous for c.1679T > G, 2 samples heterozygous for c.1905 + 1G > A, and 2 samples heterozygous for c.2846A > T. One of the 3 patient samples was heterozygous for c.1129-5923C > G (HapB3). All the variants detected by the multiplex AS-PCR assay were concordant with Sanger sequencing results.

CONCLUSIONS

A robust multiplex AS-PCR assay was developed to rapidly detect 5 variants in the DPYD gene. It can be used for screening DPYD variants to identify patients with increased risk of toxicity when prescribed fluoropyrimidine therapy.

Native Capillary Electrophoresis-Mass Spectrometry of Near 1 MDa Non-Covalent GroEL/GroES/Substrate Protein Complexes

Protein complexes are essential for proteins' folding and biological function. Currently, native analysis of large multimeric protein complexes remains challenging. Structural biology techniques are time-consuming and often cannot monitor the proteins' dynamics in solution. Here, a capillary electrophoresis-mass spectrometry (CE-MS) method is reported to characterize, under near-physiological conditions, the conformational rearrangements of ∽1 MDa GroEL upon complexation with binding partners involved in a protein folding cycle. The developed CE-MS method is fast (30 min per run), highly sensitive (low-amol level), and requires ∽10 000-fold fewer samples compared to biochemical/biophysical techniques. The method successfully separates GroEL14 (∽800 kDa), GroEL7 (∽400 kDa), GroES7 (∽73 kDa), and NanA4 (∽130 kDa) oligomers. The non-covalent binding of natural substrate proteins with GroEL14 can be detected and quantified. The technique allows monitoring of GroEL14 conformational changes upon complexation with (ATPγS)4-14 and GroES7 (∽876 kDa). Native CE-pseudo-MS3 analyses of wild-type (WT) GroEL and two GroEL mutants result in up to 60% sequence coverage and highlight subtle structural differences between WT and mutated GroEL. The presented results demonstrate the superior CE-MS performance for multimeric complexes' characterization versus direct infusion ESI-MS. This study shows the CE-MS potential to provide information on binding stoichiometry and kinetics for various protein complexes.

Development of an Online Isotope Dilution CE/ICP-MS Method for the Quantification of Sulfur in Biological Compounds

We report an analytical methodology for the quantification of sulfur in biological molecules via a species-unspecific postcolumn isotope dilution (online ID) approach using capillary electrophoresis (CE) coupled online with inductively coupled plasma-mass spectrometry (online ID CE/ICP-MS). The method was optimized using a mixture of standard compounds including sulfate, methionine, cysteine, cystine, and albumin, yielding compound recoveries between 98 and 105%. The quantity of sulfur is further converted to the quantity of the compounds owing to the prior knowledge of the sulfur content in the molecules. The limit of detection and limit of quantification of sulfur in the compounds were 1.3-2.6 and 4.1-8.4 mg L-1, respectively, with a correlation coefficient of 0.99 within the concentration range of sulfur of 5-100 mg L-1. The capability of the method was extended to quantify albumin in its native matrix (i.e., in serum) using experimentally prepared serum spiked with a pure albumin standard for validation. The relative expanded uncertainty of the method for the quantification of albumin was 6.7% (k = 2). Finally, we tested the applicability of the method on real samples by the analysis of albumin in bovine and human sera. For automated data assessment, a software application (IsoCor)─which was developed by us in a previous work─was developed further for handling of online ID data. The method has several improvements compared to previously published setups: (i) reduced adsorption of proteins onto the capillary wall owing to a special capillary-coating procedure, (ii) baseline separation of the compounds in less than 30 min via CE, (iii) quantification of several sulfur species within one run by means of the online setup, (iv) SI traceability of the quantification results through online ID, and (v) facilitated data processing of the transient signals using the IsoCor application. Our method can be used as an accurate approach for quantification of proteins and other biological molecules via sulfur analysis in complex matrices for various fields, such as environmental, biological, and pharmaceutical studies as well as clinical diagnosis.

A novel label-free capillary electrophoresis LED-induced fluorescence platform based on catalytic hairpin assembly for sensitive detection of multiple circulating tumor DNA

Circulating tumor DNA (ctDNA) is a highly promising biomarker for the early diagnosis and treatment of gastric cancer (GC). However, there is still a lack of effective and practical ctDNA detection methods. In this work, a simple and economical capillary non-gel sieving electrophoresis-LED induced fluorescence detection (NGCE-LEDIF) platform coupled with catalytic hairpin assembly (CHA) as the signal amplification strategy is proposed for quantitative detection of PIK3CA E542K and TP53 (two types of ctDNA associated with GC). We have reasonably designed two pairs of programmable oligonucleotide hairpin probes for PIK3CA E542K and TP53. Using a one-pot reaction, the presence of ctDNA triggers the cyclic amplification of CHA, forming numerous thermodynamically stable H1/H2 double-strands. The H1/H2 double-stranded DNA catalyzed by PIK3CA E542K and TP53 can be easily separated by NGCE due to their different lengths, enabling simultaneous detection of both ctDNAs. Under optimal experimental conditions, the detection limits of this strategy for detecting GC-related biomarkers PIK3CA E542K and TP53 are 20.35 pM and 19.61 pM, respectively, and can achieve 730-fold signal amplification. This strategy has a good recovery in the serum matrix. The results of this study show that this strategy has significant advantages such as high selectivity, a simple process, no special instruments and equipment, no need for fluorescence modification of hairpin probes in advance, high automation, low cost, and minimal sample consumption. This provides a powerful method for the detection of trace cancer biomarkers in the serum matrix with good application prospects.

Capillary electrophoresis tandem mass spectrometry to determine multiclass cyanotoxins in reservoir water and spinach samples

Cyanotoxins constitute a group of toxic secondary metabolites, the presence of which in any water body poses a major health risk. Moreover, advanced organisms such as edible plants exposed to these toxins, are a possible pathway for human exposure. Green analytical chemistry is demanding environmentally friendly analytical techniques. In this sense, we propose the use of capillary electrophoresis coupled to tandem mass spectrometry (CE-MS/MS) to determine a mixture of eight cyanotoxins belonging to three different classes: cyclic peptides (microcystin-LR, microcystin-RR and nodularin), alkaloids (cylindrospermopsin and anatoxin-a) and three isomeric non-protein amino acids (β-methylamino-l-alanine, 2,4-diaminobutyric acid and N-(2-aminoethyl)glycine). Separation was achieved by using an acidic background electrolyte consisting of 2 M formic acid and 20% acetonitrile in water. Parameters affecting MS/MS detection and the sheath-liquid interface were also studied. Finally, a combination of pH-junction, field-amplified sample stacking (FASS) and acid barrage as online preconcentration strategies, was employed to improve sensitivity and efficiency. The online preconcentration applied, in combination with a dual cartridge solid-phase extraction (SPE) system, allows to obtain limits of detection in the very low range of µg·L-1 for these multiclass cyanotoxins in reservoir water samples (from 0.005 to 0.10 µg·L-1). Furthermore, for the first time cyanotoxins are analysed in spinach samples through CE-MS/MS using the same SPE procedure, following lyophilisation and solid-liquid extraction with 6 mL 80 % aqueous MeOH.

Facial on-line enrichment of glycoproteins by capillary electrophoresis with boronate-functionalized poly(glycidyl methacrylate) microparticles coated column

A facial and rapid method for glycoproteins enrichment by capillary electrophoresis was developed. The 3-aminophenylboronic acid-functionalized poly(glycidyl methacrylate) microparticles (PGMA@APBA) were attached to the capillary inlet (length of ∼1.5 cm) by electrostatic self-assemble action to prepare a partially coated capillary column. The process is simple and reversible, allowing for easy renewal of the PGMA@APBA coating when its enrichment efficiency decreases. By utilizing the coated column, glycoproteins can be enriched within 2 min. The column exhibits a specific enrichment for glycoproteins and can be consecutively used for approximately 60 runs. The relative standard deviations (RSDs) of peak area of run-to-run (n = 5) and batch-to-batch (n = 3) were 1.5 % and 1.0%, respectively. The method was successfully applied to enrich glycoproteins from 1 × 1012-fold diluted real egg white sample, indicating its practical applicability.

Evaluation of greenness and analytical performances of separative methods for chiral separation of novel lactam-based P2RX7-antagonists

In this work, a preparative supercritical fluid chromatography (SFC) method was first developed to separate a series of chiral compounds evaluated as lactam-based P2RX7 antagonists. Subsequently, high-performance liquid chromatography, SFC, and capillary electrophoresis (CE) were comparatively investigated as QC tools to determine the enantiomeric purity of the separated isomers, including analytical performance and greenness. The screening of the best conditions was carried out in liquid and SFC on the nine derivatives and the amylose tris(3,5-dimethylphenylcarbamate)-based chiral stationary phase was found to be highly efficient. The same screening was carried out in CE and very different conditions, either in acidic or basic background electrolyte and different cyclodextrins used as chiral selectors, allowed the separation of six of the nine derivatives. 1-((3,4-Dichlorophenyl)carbamoyl)-5-oxopyrrolidine-2-carboxylic acid (compound 1) was chosen as a probe, and its semi-preparative separation by SFC and enantiomeric verification using the three techniques are presented. Its limit of detection and limit of quantification are calculated for each method. Finally, the greenness of each quality control method was evaluated.

Coupling capillary electrophoresis with mass spectrometry for the analysis of oxidized phospholipids in human high-density lipoproteins

The oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (ox-PAPC) products in human high-density lipoproteins (HDLs) were investigated by low-flow capillary electrophoresis-mass spectrometry (low-flow CE-MS). To accelerate the optimization, native PAPC (n-PAPC) standard was first analyzed by a commercial CE instrument with a photodiode array detector. The optimal separation buffer contained 60% (v/v) acetonitrile, 40% (v/v) methanol, 20 mM ammonium acetate, 0.5% (v/v) formic acid, and 0.1% (v/v) water. The selected separation voltage and capillary temperature were 20 kV and 23°C. The optimal CE separation buffer was then used for the low-flow CE-MS analysis. The selected MS conditions contained heated capillary temperature (250°C), capillary voltage (10 V), and injection time (1 s). No sheath gas was used for MS. The linear range for n-PAPC was 2.5-100.0 µg/mL. The coefficient of determination (R2 ) was 0.9918. The concentration limit of detection was 1.52 µg/mL, and the concentration limit of quantitation was 4.60 µg/mL. The optimal low-flow CE-MS method showed good repeatability and sensitivity. The ox-PAPC products in human HDLs were determined based on the in vitro ox-PAPC products of n-PAPC standard. Twenty-one ox-PAPC products have been analyzed in human HDLs. Uremic patients showed significantly higher levels of 15 ox-PAPC products than healthy subjects.

Rapid characterization of adeno-associated virus (AAV) capsid proteins using microchip ZipChip CE-MS

Adeno-associated viruses (AAVs) are viral vectors used as delivery systems for gene therapies. Intact protein characterization of AAV viral capsid proteins (VPs) and their post-translational modifications is critical to ensuring product quality. In this study, microchip-based ZipChip capillary electrophoresis-mass spectrometry (CE-MS) was applied for the rapid characterization of AAV intact VPs, specifically full and empty viral capsids of serotypes AAV6, AAV8 and AAV9, which was accomplished using 5 min of analysis time. Low levels of dimethyl sulfoxide (4%) in the background electrolyte (BGE) improved MS signal quality and component detection. A sensitivity evaluation revealed consistent detection of VP proteoforms when as little as 2.64 × 106 viral particles (≈26.4 picograms) were injected. Besides the traditional VP proteoforms used for serotype identification, multiple VP3 variants were detected, including truncated VP3 variants most likely generated by leaky scanning as well as unacetylated and un-cleaved VP3 proteoforms. Phosphorylation, known to impact AAV transduction efficiency, was also seen in all serotypes analysed. Additionally, low abundant fragments originating from either N- or C-terminus truncation were detected. As the aforementioned VP components can impact product quality and efficacy, the ZipChip's ability to rapidly characterize them illustrates its strength in monitoring product quality during AAV production.

A new device for online nanoscale sampling and capillary electrophoresis analysis of plant sap composition

In this work, an online sampling of plant xylem sap combined with an efficient (CE)-based method was developed and applied to study the kinetics of changes in the sap composition and to assess plant fitness under stress conditions comprehensively. A laboratory-built CE device was developed to provide online sampling and CE analysis of various ionogenic species in the sap during plant stress response. The rapid online sampling and short CE analysis time allow for real-time monitoring of changes in sap constituents in the living plant during the stress response. The developed device was successfully used to analyze chloride, nitrate, and sulfate ions in the plant xylem during the salt stress or stress caused by nitrate deficiency within short time scales.

Cyclic Multiple Primer Generation Rolling Circle Amplification Assisted Capillary Electrophoresis for Simultaneous and Ultrasensitive Detection of Multiple Pathogenic Bacteria

Efficient, accurate, and economical detection of pathogenic bacteria is crucial in ensuring food safety and preventing foodborne illnesses. How to fulfill the highly sensitive and simultaneous detection of multiple trace pathogenic bacteria is a big challenge. In this work, capillary electrophoresis coupled with a cyclic multiple primer generation rolling circle amplification (cyclic MPG-RCA) was studied for highly sensitive and simultaneous detection of three kinds of pathogenic bacteria. The cyclic MPG-RCA was based on a carefully designed clover-shaped DNA probe, in which three "leaves" corresponded to three types of aimed pathogenic bacteria: Shigella dysenteriae (S. dysenteriae), Salmonella enterica subsp. enterica serovar Typhi (S. Typhi), and Vibrio parahaemolyticus (V. parahaemolyticus). Under the optimal experimental conditions, the limits of detection (S/N = 3) of this method for bacterial target DNA were 11.4 amol·L-1 (S. dysenteriae), 4.88 amol·L-1 (S. Typhi), and 14.9 amol·L-1 (V. parahaemolyticus), and the conversion concentrations for the target bacteria were 10 colony-forming units (CFU)·mL-1 (S. dysenteriae), 3 CFU·mL-1 (S. Typhi), and 12 CFU·mL-1 (V. parahaemolyticus). This method had been applied to the detection of tap water samples with good results, which proved that it could be used as an effective tool for trace pathogenic bacteria monitoring in foods, environments, and medicines.

Steady state microdialysis of microliter volumes of body fluids for monitoring of amino acids by capillary electrophoresis with contactless conductivity detection

BACKGROUND

The availability of dialysis membranes in the form of hollow fibres with diameters compatible with the fused silica capillaries used in capillary electrophoresis is very limited. However, haemodialysis bicarbonate cartridges commonly used in human medicine containing polysulfone hollow fibres are available on the market and are used for the fabrication of coaxial microdialysis probes. The miniature probe design ensures that steady-state conditions are achieved during microdialysis of minimal volumes of body fluids.

RESULTS

A coaxial microdialysis probe with a length of 5 cm and an inner diameter of 200 μm is used for microdialysis of 10 μL of body fluid collected into a sampling fused silica capillary with an inner diameter 430 μm. Microdialysis is performed into 0.01 M HCl as a perfusate at stopped flow and 2 μL of the resulting microdialysate are subjected to analysis by capillary electrophoresis with contactless conductivity detection. Microdialysis pre-treatment is verified by analysis of 11 common amino acids at a 100 μM concentration level, resulting in recoveries of 98.3-102.5%. The electrophoretic separation of amino acids is performed in 8.5 M acetic acid at pH 1.37 as a background electrolyte with analysis time up to 4.5 min and LOD in the range of 0.12-0.28 μM. The reproducibility of the developed technique determined for the peak area ranges from 1.2 to 4.5%. Applicability is tested in the quantification of valine and leucine in plasma during fasting and subsequent reconvalescence.

SIGNIFICANCE

The fabrication of a coaxial microdialysis probe for the laboratory preparation of microliter volumes of various types of clinical samples is described, which is coupled off-line with capillary electrophoretic monitoring of amino acids in 2 μL volumes of microdialysate. The developed methodology is suitable for quantification of 20 amino acids in whole human blood, plasma, tears and has potential for analysis of dry blood spots captured on hollow fibre.

Estimation of Human Chronological Age from Buccal Swab Samples through a DNA Methylation Analysis Approach of a Five-Locus Multiple Regression Model

Recent advancements in forensic genetics have facilitated the extraction of additional characteristics from unidentified samples. This study delves into the predictive potential of a five-gene (ELOVL2, FHL2, KLF14, C1orf132, and TRIM59) methylation rate analysis for human age estimation using buccal swabs collected from 60 Italian volunteers. The methylation levels of specific CpG sites in the five genes were analyzed through bisulfite conversion, single-base extension, and capillary electrophoresis. A multivariate linear regression model was crafted on the training set, then the test set was employed to validate the predictive model. The multivariate predictive model revealed a mean absolute deviation of 3.49 years in the test set of our sample. While limitations include a modest sample size, the study provides valuable insights into the potential of buccal swab-based age prediction, aiding in criminal investigations where accurate age determination is crucial. Our results also highlight that it is necessary to investigate the effectiveness of predictive models specific to biological tissues and individual populations, since models already proven effective for other populations or different tissues did not show the same effectiveness in our study.

A methodological approach by capillary electrophoresis coupled to mass spectrometry via electrospray interface for the characterization of short synthetic peptides towards the conception of self-assembled nanotheranostic agents

Nanostructures formed by the self-assembling peptide building blocks are attractive materials for the design of theranostic objects due to their intrinsic biocompatibility, accessible surface chemistry as well as cavitary morphology. Short peptide synthesis and modification are straightforward and give access to a great diversity of sequences, making them very versatile building blocks allowing for the design of thoroughly controlled self-assembled nanostructures. In this work, we developed a new CE-DAD-ESI-MS method to characterize short synthetic amphiphilic peptides in terms of exact sequence and purity level in the low 0.1 mg.mL-1 range, without sample treatment. This study was conducted using a model sequence, described to have pH sensitive self-assembling property. Peptide samples obtained from different synthesis processes (batch or flow, purified or not) were thus separated by capillary zone electrophoresis (CZE). The associated dual UV and MS detection mode allowed to evidence the exact sequence together with the presence of impurities, identified as truncated or non-deprotected sequences, and to quantify their relative proportion in the peptide mixture. Our results demonstrate that the developed CE-DAD-ESI-MS method could be directly applied to the characterization of crude synthetic peptide products, in parallel with the optimization of peptide synthetic pathway to obtain controlled sequences with high synthetic yield and purity, which is crucial for further design of robust peptide based self-assembled nanoarchitectures.

Direct SARS-CoV-2 Detection System Utilizing Simple-to-Use Capillary Gel Electrophoresis Sample-to-Result

AIM

We present a Direct SARS-CoV-2 Detection System that achieves sample-to-results in less than two hours in three simple steps.

METHODS

The Detection System includes Direct one-step Reverse Transcription PCR (RT-PCR) reagents (Qexp-MDx kit), a portable thermal cycler (Qampmini) with a preprogrammed chip and a simple-to-use Capillary Gel Electrophoresis system (Qsep Series Bio-Fragment Analyzer) with high fluorescence detection sensitivity to solve the problems associated with traditional real-time PCR (qPCR) systems which produces high false positive results.

RESULTS

The proposed simple-to-use detection platform can provide high detection sensitivity (identify less than 20 copies) and fast results (less than 120 minutes), which would be suitable for field testing applications.

CONCLUSION

Our high detection sensitivity platform provides fast and accurate results in 120 minutes without doing DNA/RNA extraction.

Determination of scopolamine and butylscopolamine in beverages, urine and Buscopan® tablets samples using electrophoresis microchip with integrated contactless conductivity detection

The number of cases in which scopolamine (SCO) was used for both recreational and predatory purposes has increased dramatically in recent decades. Linked to this, there is a concern about obtaining SCO through thermal degradation of butylscopolamine (BSCO) - an active ingredient of Buscopan® - a drug sold without a medical prescription. In this study, mixtures containing SCO and BSCO were separated and detected on a microchip electrophoresis (ME) device with integrated capacitively coupled contactless conductivity detection (C4D) using a running buffer composed of 40 mmol L-1 of butyric acid and 25 mmol L-1 of sodium hydroxide (pH 5.0). The separation was performed within ca. 115 s with a resolution of 1.3 and separation efficiency ranging from 1.4 × 105 to 1.5 × 105 theoretical plates m-1. A detection limit of 1.1 μmol L-1 was achieved for both species and the developed method revealed satisfactory repeatability with relative standard deviation (RSD) values for forty-eight injections between 4.8 and 9.4% for peak areas and lower than 3.3% for migration times. Furthermore, inter-day precision was evaluated for sixteen injections (a sequence of four injections performed over four days), and RSD values were less than 6.6% for peak areas and 2.2% for migration times. Satisfactory recovery values (95-114%) were obtained for all evaluated beverage samples (cachaça, vodka, whiskey, beer, Coca-Cola, and grape juice) as well as for artificial urine samples (95-107%). Finally, the conversion of BSCO into SCO was observed after simple heating procedure of Buscopan® sample (not subject to medical prescription), which was successfully confirmed through analysis by capillary electrophoresis coupled to the mass spectrometry (CE-MS). Based on the reported results, the use of ME-C4D devices has demonstrated a huge potential for applications in the forensic chemistry field.

The establishment of a multiplex fluorescent polymerase chain reaction coupled with capillary electrophoresis analysis technology enables the simultaneous detection of 16 genotypes of human papillomavirus

BACKGROUND

The detection and accurate genotyping of human papillomavirus (HPV) infection is critical for preventing and effectively treating cervical cancer.

METHODS

A multiplex fluorescent polymerase chain reaction (PCR) coupled with a capillary electrophoresis method was developed for the simultaneous detection of the 16 most prevalent HPV genotypes. Twenty-five pairs of primers were ultimately selected to ensure that both E and L regions of nine HPV genotypes, as well as the E regions of seven HPV genotypes could be accurately amplified.

RESULTS

This method enables the simultaneous detection and differentiation of 16 HPV genotypes in a single closed-tube reaction, accurately distinguishing products with molecular weight differences >1 bp through capillary electrophoresis. This method demonstrated exceptional accuracy, specificity, and repeatability with a detection limit of 10 copies/μL for all 16 HPV genotypes. Furthermore, 152 cervical swab specimens were obtained to compare the disparities between this approach and Cobas 4800 HPV detection method. The concordance rate and κ value were 90.1% and 0.802, respectively, indicating a high level of agreement. The established detection method was successfully applied to cervical swab specimens for determining HPV genotypes across all levels of cervical lesions, HPV52, 56, 16, and 59 were found to be most prevalent with infection rates of 10.8%, 9.1%, 6.5%, and 6.2%, respectively.

CONCLUSIONS

This study has successfully established a detection method capable of simultaneously identifying 16 HPV genotypes. This approach can be further applied to HPV vaccine research and surveillance, with the potential for broad applications.

Screening of Acetylcholinesterase Inhibitors by Capillary Electrophoresis with Oriented-Immobilized Enzyme Microreactors Based on Gold Nanoparticles

A facial and efficient method for the screening of acetylcholinesterase (AChE) inhibitors by capillary electrophoresis was developed. Based on the specific affinity of concanavalin A (Con A) for binding to the glycosyl group of AChE, enzyme molecules were oriented-immobilized on the surface of gold nanoparticles (AuNPs@Con A@AChE). Then, these modified nanoparticles were bounded to the capillary inlet (about 1.0 cm) by electrostatic self-assembly to obtain the oriented-immobilized enzyme microreactor (OIMER). Compared to an IMER with a free enzyme, the peak area of the product obtained by the OIMER increased by 52.6%. The Michaelis-Menten constant (Km) was as low as (0.061 ± 0.003) mmol/L. The method exhibits good repeatability with a relative standard deviation (RSD) of 1.3% for 100 consecutive runs. The system was successfully applied to detect the IC50 values of donepezil and four components from Chinese medicinal plants. This work demonstrates the potential of this method as a low cost, simple, and accurate screening method for other enzyme inhibitors.

Identification of double heterozygous -α4.2Ⅰ/-α4.2Ⅱ using third-generation sequencing

OBJECTIVE

The 4.2 kb deletion (-α4.2/) is a common a+-thalassemia with a carrier rate, followed by the South-East Asian deletion (-SEA) and the 3.7 kb deletion (-α3.7/). There are few reports about 4.2 kb deletion sub-types. Herein, we present a patient with double heterozygous -α4.2Ⅰ/-α4.2Ⅱwho was identified using third-generation sequencing (TGS).

METHODS

Hematology and hemoglobin fraction analysis were carried out by complete blood count (CBC) and capillary electrophoresis (CE). Gap-PCR was used to detect the common deletional α-thalassemia, and multiple ligation-dependent probe amplification (MLPA) was performed to screen the large deletion. Sanger sequencing identified the variant. The different deletions were confirmed by TGS.

RESULTS

CBC showed the patient with microcytic hypochromic anemia, and CE indicated the presence of a Hb variant. Gap-PCR and MLPA detected 4.2 kb deletion homozygotes (-α4.2/-α4.2). The Hb variant was confirmed as Hb Q-Thailand by Sanger sequencing. The patient was identified as compound heterozygous of 4.2 kb deletion and Hb Q-Thailand (-α4.2/-α4.2-Q-Thailand, -α4.2Ⅰ/-α4.2Ⅱ) using TGS.

CONCLUSIONS

Hb Q-Thailand (-α4.2-Q-Thailand/) complex 4.2 kb deletion heterozygote (-α4.2/) is easily misdiagnosed as 4.2 kb homozygous using Gap-PCR and MLPA. The TGS enables the identification of the two different 4.2 kb deletion sub-types.

An innovative detection technique for capillary electrophoresis: Localized terahertz emission-time domain spectroscopy

Terahertz (THz) time-domain spectroscopy (TDS) is a recently emerging analysis method which can provide unique information on molecular vibration and rotation induced by inter/intra-molecular interactions. Although the application of THz-TDS to high-performance microscale separation methods like capillary electrophoresis (CE) has been anticipated, it has been hindered due to the diffraction limit of THz wave (typically, hundreds µm). In order to realize CE-THz-TDS, in this study, we placed a narrow open-tubular capillary on the surface of a GaAs semiconductor substrate as a "localized" THz-emitter. By focusing femtosecond pulsed laser beams at the surface of a gallium arsenide (GaAs) substrate closest to the capillary, THz waves were locally generated to pass through the capillary, so that THz absorbance spectra were obtained from the capillary which has narrower inner diameter than the diffraction limit. As a typical result from acetic acid analysis in the CE-THz-TDS platform, information on the refractive index and extinction coefficient was obtained, which showed non-linear and linear concentration dependence, respectively, similar to conventional THz-TDS using large liquid cells. Finally, CE-THz-TDS analysis of several carboxylic acids was demonstrated. Two acids were successfully separated and detected with THz-TDS, where their electrophoretic mobility values were estimated as close to those obtained with conventional contactless conductivity detection. Our proposed CE-THz-TDS showed the potential for the systematic analysis of inter/intra-molecular weak interactions like hydrogen bonds, which are unable to obtain with conventional detectors.

The affinity of histamine to serum albumin: Capillary electrophoresis-frontal analysis and in-silico molecular docking approaches

Histamine is a biogenic amine found in various body tissues and responsible for many critical vital activities. It is also responsible for allergic reactions in the body. Ingestion of foods containing high amounts of histamine can cause fatal allergic reactions. Albumin in plasma controls drugs and free concentrations of bioactive constituents taken to the body with food. Hence, this study aimed to characterise the interactions of histamine with bovine serum albumin. Capillary electrophoresis in the frontal analysis mode was employed in this study as a practical approach for assessing histamine-bovine serum albumin affinity. The plateau-shaped free histamine peak was well separated from the bovine serum albumin (BSA)-histamine complex peak. The free histamine concentration was obtained by following the height of the free histamine peak. Whereas the bound histamine concentrations were obtained by calculating the difference between the height of total and free histamine peaks. Histamine bound to BSA at one independent site with a Kb value of 2.50 × 103 L/mol. Moreover, an in-silico molecular docking method was performed, and it was revealed that the binding site of histamine was located closer to Lysine-131 in subdomain IIA of bovine serum albumin.

Online preconcentration and chiral separation of ofloxacin in exhaled breath condensate by capillary electrophoresis

Breath analysis is an effective method of monitoring systemic or respiratory ailments. A simple chiral capillary electrophoresis method coupled with an online field-amplified sample injection stacking method is presented for ultratrace quantification of the enantiomers of ofloxacin in exhaled breath condensate (EBC). The study is focused on the use of EBC as an easily available biological sample to monitor ofloxacin's enantiomers levels with good patient compliance. The proposed method was validated in accordance with FDA guidelines over the concentration range of 0.004-1.0 µg mL-1 of racemic ofloxacin. Inter- and intra-day precision and accuracy were within the acceptable limit (below 8.50 %). The method was specific for routine analysis of ofloxacin's enantiomers. A small volume of EBC samples from seven patients under ofloxacin therapy was analyzed using the proposed method in which the concentrations of "R" and "S" enantiomers were between 0.0026 and 0.056 µg mL-1.

Developments in on-line, post separation sample manipulation in the last 22 years: Pharmaceutical and biomedical applications

On-line post separation sample manipulation is a powerful approach increasing the sensitivity and selectivity in chemical analysis. Post separation sample manipulation includes the treatment of the analytes after their separation through a suitable separation technique, mainly liquid chromatography and capillary electrophoresis. Typically, post separation approaches include either the addition of a reagent/solvent to derivatize the analyte/enhance the sensitivity, pH change, or the conversion of the analyte through a photochemical/electrochemical system (reagent-free systems). This review focuses on the developed methods using post-column manipulation of sample with pharmaceuticals and biomedical applications, covering the period from 2000 to midle-2023. Chemistries combined with fluorescence, UV-vis and mass spectrometric detection are discussed employing both liquid chromatography and electrophoretic techniques for separation. Noteworthy instrumental modifications are also discussed.

Carboxymethylated maltodextrin as a chiral selector for the separation of some basic drug enantiomers using capillary electrophoresis

In this work, carboxymethylated maltodextrin (Cm-MD) was successfully synthesized as an efficient anionic chiral selector and applied for the enantiomer separation of some basic drugs including tramadol, venlafaxine, verapamil, hydroxyzine, citalopram, fluoxetine, and amlodipine by capillary electrophoresis (CE). The synthesized chiral selector was characterized by the nuclear magnetic resonance and Fourier transform infrared spectrophotometry. Under the optimized Cm-MD modified CE conditions (background electrolyte: phosphate buffer (pH 5.0, 50 mM) containing 5% (w/v) Cm-MD; applied voltage: 20 kV; and capillary column temperature: 25 °C), successful enantiomer separation of all studied chiral drugs were observed. By comparison of Cm-MD and MD for enantiomer separation of the model drugs, it was revealed that Cm-MD exhibits a higher resolution in comparison to the MD modified CE. This enhanced resolution could be attributed to the electrostatic interactions between the cationic drugs and anionic Cm-MD and opposite direction mobility of the host-guest complex relative to the chiral analyte. The optimized Cm-MD modified CE method was successfully used for the assay of the enantiomers of citalopram and venlafaxine in commercial tablets. The proposed method showed the linear range of 5.0-150.0 mg/L and 10.0-150.0 mg/L for both enantiomers of citalopram and venlafaxine, respectively. The limits of quantification were 5.0 and 10.0 mg/L for the enantiomers of citalopram and venlafaxine, respectively. The limit of detection for all enantiomers was found to be < 3.0 mg/L. Intra- and inter-day RSDs (n = 4) were less than 9.7%. The relative errors were less than 9.4% for all enantiomers. The obtained results in this research show that Cm-MD as a new, efficient and inexpensive chiral selector can be used for enantiomer separation of basic drugs using the CE technique.

A comprehensive review of capillary electrophoresis-based techniques for erythropoietin isoforms analysis

Different CE techniques have been used to analyze erythropoietin. These techniques have been shown to be effective in differentiating and quantifying erythropoietin isoforms, including natural and recombinant origins. This review provides a comprehensive overview of various capillary electrophoresis-based techniques used for the analysis of erythropoietin isoforms. The importance of erythropoietin in clinical practice and the necessity for the accurate analysis of its isoforms are first discussed. Various techniques that have been used for erythropoietin isoform analysis are then described. The main body of the review focuses on the different capillary electrophoresis-based methods that have been developed for erythropoietin isoform analysis, including capillary zone electrophoresis and capillary isoelectric focusing. The advantages and drawbacks of each method as well as their applications are discussed. Suggestions into the future directions of the area are also described.

Determination of rhein and physcion in rhubarb by microchip capillary electrophoresis in mixed hydro-organic solvent combined with laser-induced fluorescence detection

Microchip capillary electrophoresis in mixed hydro-organic solvent combined with laser-induced fluorescence detection was developed for the separation and detection of physcion and rhein in rhubarb. In contrast to the conventional capillary electrophoresis method, ammonium acetate-dimethyl sulfoxide was used as the basic buffer system in this method. The effects of background buffer, buffer apparent pH*, buffer concentration, water ratio, sample preparation method, and separation voltage on separation and detection were investigated. Optimized separation and detection conditions were obtained: the buffer consisted of 20 mmol/L of ammonium acetate in hydro-organic solvent composed dimethyl sulfoxide, formamide, and water mixed at 60/20/20 (v/v/v) ratio. The separation voltage was 1.9 kV. Under these conditions, the physcion, rhein, and other components of rhubarb can be completely separated within 150 s. Under the methodological verification, good linearity (R ≥ 0.9995) for physcion and rhein, and low limits of detection (0.085 μg·mL-1 and 0.077 μg·mL-1 , respectively), satisfactory peak area precisions, migration time precisions (1.74%-3.09%), and accuracy (recovery rate 97.8% and 101.4%) were achieved. It is shown that the proposed method is simple, efficient, fast, sensitive, simple instrument, consumes few samples, has low operating cost, and is linear.

A preliminary exploration for co-detecting RNA virus and STR type on capillary electrophoresis in forensic practice

RNA virus infection such as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection shows severe respiratory symptoms on human and could be an obvious individual characteristic for investigations in forensic science. As for biological samples suspected to contain RNA virus in forensic casework, it requires respective detection of viral RNA and human DNA: reverse transcriptase polymerase chain reaction and DNA type (short tandem repeat [STR] analysis). Capillary electrophoresis (CE) has been shown to be a versatile technique and used for a variety of applications, so we preliminarily explored the co-detection of RNA virus and STR type on CE by developing a system of co-detecting SARS-CoV-2 and STR type under ensuring both the efficiency of forensic DNA analysis and safety of the laboratory. This study investigated the development and validation of the system, including N and ORF1ab primer designs, polymerase chain reaction amplification, allelic ladder, CE detection, thermal cycling parameters, concordance, sensitivity, species specificity, precision, and contrived and real SARS-CoV-2 sample studies. Final results showed the system could simultaneously detect SARS-CoV-2 and STR type, further indicating that CE has possibilities in the multi-detection of RNA viruses/STR type to help to prompt individual characteristics (viral infection) and narrow the scope of investigation in forensic science.

False HbA1cValue due to a Rare Variant of Hemoglobin J-Cubujuqui

BACKGROUND

Hemoglobin (Hb) J-Cubujuqui is a rare Hb variant, and reports about it are very limited. There are no descriptions that it affects the results of glycated Hb.

METHODS

In this study, we describe a rare variant discovered during newborn screening. Both high-performance liquid chromatography (HPLC) and capillary electrophoresis for hemoglobin analysis displayed abnormal peaks. The Hb variant was confirmed by Sanger sequencing.

RESULTS

The pedigree study shows the variant was inherited from the newborn's father. His fasting blood glucose (FBG) level was 5.5 mmol/L. HbA1c measured by HPLC was falsely low in her father (2.41%), whereas that measured by immunoassay was normal (5.11%). Sanger sequencing revealed a heterozygous mutation (CGT˃AGT) at amino acid position 141 of the α1 gene, corresponding to Hb J-Cubujuqui [α1 141(HC3) Arg→Ser (CGT˃AGT); HBA1:c.424C˃A (or HBA2)].

CONCLUSIONS

This is the first report that Hb J-Cubujuqui interferes with the measurement of HbA1cand prompts clinicians to pay attention to the accuracy of glycated Hb results.

Development and validation of capillary electrophoresis sodium dodecyl sulfate (CE-SDS) method for purity analysis of pertussis toxin, filamentous haemagglutinin and pertactin antigens

We report here the development and validation of CE-SDS method for purity analysis of Acellular Pertussis vaccine components viz. purified Pertussis toxin (PTx), purified Filamentous haemagglutinin (FHA), and Pertactinantigen (PRN). The method was found to be specific and showed excellent linearity at a concentration range of 15.62 µg/mL-1000 µg/mL for purified PTx, 31.25 µg/mL-1000 µg/mL for purified FHA, and 3.9 µg/mL-1000 µg/mL for PRN antigen. Method reported limit of quantification (LOQ) 31.25 µg/mL, 62.5 µg/mL, and 7.8 µg/mL for purified PTx, FHA, and PRN respectively. Method precision (repeatability and intermediate precision) for purity and molecular weight determination in product matrix was below 10% for all three proteins. Method comparability studies were performed with SDS-PAGE. CE-SDS demonstrated corroborating results with SDS-PAGE for the estimation of purity and molecular weight analysis. However, CE-SDS method exhibited better resolution capabilities for resolving all the sub-unit peaks of PTx and isoforms of purified FHA. CE-SDS method also demonstrated stability indicating potential and thus fits its intended purpose as an effective analytical tool for quality control of acellular pertussis-based vaccines.

Miniaturized matrix solid-phase dispersion and solid-phase clear-up combined with capillary electrophoresis for efficient determination of trace bioactive components in complicated sample matrix: Take Wubi Shanyao Pill as an example

Accurate quantitative analysis of trace analytes in a complicated matrix is a challenge in modern analytical chemistry. An appropriate analytical method is considered to be one of the most common gaps during the whole process. In this study, a green and efficient strategy based on miniaturized matrix solid-phase dispersion and solid-phase extraction combined with capillary electrophoresis was first proposed for extracting, purifying and determining target analytes from complicated matrix, using Wubi Shanyao Pill as an example. In detail, 60 mg of samples were dispersed on MCM-48 to obtain high yields of analytes, then the extract was purified with a solid-phase extraction cartridge. Finally, four analytes in the purified sample solution were determined by capillary electrophoresis. The parameters affecting the extraction efficiency of matrix solid-phase dispersion, purification efficiency of solid-phase extraction and separation effect of capillary electrophoresis were investigated. Under the optimized conditions, all analytes demonstrated satisfactory linearity (R2 >0.9983). What's more, the superior green potential of the developed method for the determination of complex samples was confirmed by the Analytical GREEnness Metric Approach. The established method was successfully applied in the accurate determination of target analytes in Wubi Shanyao Pill and thus provided reliable, sensitive, and efficient strategy support for its quality control.

Capillary Zone Electrophoresis-Tandem Mass Spectrometry for Top-Down Proteomics of Mouse Brain Integral Membrane Proteins

Mass spectrometry (MS)-based top-down characterization of integral membrane proteins (IMPs) is crucial for understanding their functions in biological processes. However, it is technically challenging due to their low solubility in typical MS-compatible buffers. In this work, for the first time, we developed an efficient capillary zone electrophoresis (CZE)-tandem MS (MS/MS) method for the top-down proteomics (TDP) of IMPs enriched from mouse brains. Our technique employs a sample buffer containing 30% (v/v) formic acid and 60% (v/v) methanol for solubilizing IMPs and utilizes a separation buffer of 30% (v/v) acetic acid and 30% (v/v) methanol for maintaining the solubility of IMPs during CZE separation. Single-shot CZE-MS/MS identified 51 IMP proteoforms from the mouse brain sample. Coupling size exclusion chromatography (SEC) to CZE-MS/MS enabled the identification of 276 IMP proteoforms from the mouse brain sample containing 1-4 transmembrane domains. This proof-of-concept work demonstrates the high potential of CZE-MS/MS for the large-scale TDP of IMPs.

Fractionation of bacteria by electrophoresis as pre-separation method before MALDI-MS detection

The present study attempted to apply the capillary electrophoresis technique for the fractionation and separation of S. Staphylococcus hominis and Escherichia coli bacteria isolated from urine samples and the detection of migrated fraction with spectrometric method. This involved the selection of suitable conditions for separation as well as the identification of pathogens. The result of the research was the separation of Gram-negative and Gram-positive bacteria, as well as their subsequent identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry using two different approaches (culture of fractions on an agar plate and direct analysis of the collected fractions). The preliminary results provide a solid basis for further research on the use of electromigration techniques with LDI detection to identify pathogens such as bacteria and viruses in biological samples.

Analysis of metabolite differences between South Korean and Chinese yellow goosefish (Lophius litulon) using capillary electrophoresis time-of-flight mass spectrometry

The yellow goosefish is a benthic fish that belongs to the family Lophiidae and order Lophiiformes and is distributed in the Yellow and East China Seas. This study aimed to distinguish between yellow goosefish from different geographical origins by analyzing their metabolites. Capillary electrophoresis time-of-flight mass spectrometry was used to analyze metabolite profiles in the muscle tissues of yellow goosefish to distinguish between Korean and Chinese yellow goosefish. In total, 271 putative metabolites were extracted using 50% acetonitrile in water. Principal component analysis and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to distinguish different geographical origins using the metabolite profiles obtained. The R2 and Q2 values of the OPLS-DA model were 0.856 and 0.695, respectively, indicating that the model was well-fitted and had good predictability. The heat map revealed that nucleic acid and amino compounds differed between the Korean and Chinese fish, and the variable importance in the projection scores obtained from OPLS-DA showed that there were geographical differences in the primary metabolites (5'-methylthioadenosine, adenosine, uridine 5-diphosphate, guanosine 5-diphosphate, urea, homocarnosine, O-acetylcarnitine, cycloleucine, cycloleucine S-adenosylmethionine, S-adenosylhomocysteine, ethanolamine, myo-inositol 1-phosphate), which were identified as potential candidate biomarkers.

[Hemoglobin C Variant Affecting Glycated Hemoglobin Test Results: A Rare Case Report]

Hemoglobin (Hb) variants are common factors that affect the results of glycosylated hemoglobin (A1C) tests. Hemoglobin variants react differently to different testing methods. Herein, we presented the first ever report of the effect of hemoglobin C (Hb C) on the test results of A1C in the Chinese population. High performance liquid chromatography (HPLC) and capillary electrophoresis were performed to measure A1C. Hemoglobin electrophoresis was conducted to identify the hemoglobin variants. Hb sequencing was performed to determine the mutation sites on the β chain. HPLC showed decreased A1C results, which could be corrected by electrophoresis, but the electrophoresis graph still showed abnormal peaks. The hemoglobin electrophoresis results suggested that there were hemoglobin variants, which hemoglobin sequencing results revealed to be Hb C. Uncommon variations in a specific population tend to be overlooked. To avoid clinical decision-making being affected by the results of a single test, we recommend that an explanatory reporting model be routinely adopted for A1C tests so that all reports always contain explanatory notes for the testing methodology and analysis of the graphs.

Cutting-Edge Technologies Driving Quantitative Mass Spectrometry

ARTICLES DISCUSSED

Correa, C. N., Fiametti, L. O., Esquinca M. E. M., de Castro, L. M. Sample preparation and relative quantitation using reductive methylation of amines for peptidomics studies. Journal of Visualized Experiments. (177), doi:10.3791/62971 (2021). Vanderwall, D. et al. JUMPn: A streamlined application for protein co-expression clustering and network analysis in proteomics. Journal of Visualized Experiments. (176), doi:10.3791/62796 (2021). Qiu, D., Eisenbeis, V. B., Saiardi, A., Jessen, H. J. Absolute quantitation of inositol pyrophosphates by capillary electrophoresis electrospray ionization mass spectrometry. Journal of Visualized Experiments. (174), doi:10.3791/62847 (2021). Smolen, K. A., Kettenbach, A. N. A mass spectrometry-based approach to identify phosphoprotein phosphatases and their interactors. Journal of Visualized Experiments. (182), doi:10.3791/63805 (2022).

Liquid Plasticine-Based Electrokinetic Enrichment of Proteins

Protein analysis is an important approach for disease diagnosis, in which sample pretreatment is an essential step since protein samples are often complex and many protein biomarkers are of low abundance. Here, given the good openness and light transmission of liquid plasticine (LP), which is a liquid entity formed by SiO₂ nanoparticles and encapsulated aqueous solution, we developed a LP-based field-amplified sample stacking (FASS) system for protein enrichment. The system was composed of a LP container, a sample solution and a Tris-HCl solution containing hydroxyethyl cellulose (HEC). The system design, mechanism investigation, optimization of experimental parameters and characterization of LP-FASS performance for protein enrichment were well studied. Under the optimized experimental conditions of 1 % HEC, 100 mm Tris-HCl and 100 V in the LP-FASS system, a 40-80 times enrichment of proteins was obtained in 40 min using bovine hemoglobin (BHb) as the model protein using the constructed LP-FASS system. The simultaneous enrichment of multiple proteins (phycocyanin, BHb and cytochrome C) was also realized using the system. The LP-FASS system can serve as a new platform for protein enrichment which is easy to be combined with online and offline detections.

From Capillary Electrophoresis to Deep Sequencing: An Improved HIV-1 Drug Resistance Assessment Solution Using In Vitro Diagnostic (IVD) Assays and Software

BACKGROUND

Drug-resistance mutations were mostly detected using capillary electrophoresis sequencing, which does not detect minor variants with a frequency below 20%. Next-Generation Sequencing (NGS) can now detect additional mutations which can be useful for HIV-1 drug resistance interpretation. The objective of this study was to evaluate the performances of CE-IVD assays for HIV-1 drug-resistance assessment both for target-specific and whole-genome sequencing, using standardized end-to-end solution platforms.

METHODS

A total of 301 clinical samples were prepared, extracted, and amplified for the three HIV-1 genomic targets, Protease (PR), Reverse Transcriptase (RT), and Integrase (INT), using the CE-IVD DeepChek^® Assays; and then 19 clinical samples, using the CE-IVD DeepChek^® HIV Whole Genome Assay, were sequenced on the NGS iSeq100 and MiSeq (Illumina, San Diego, CA, USA). Sequences were compared to those obtained by capillary electrophoresis. Quality control for Molecular Diagnostics (QCMD) samples was added to validate the clinical accuracy of these in vitro diagnostics (IVDs). Nineteen clinical samples were then tested with the same sample collection, handling, and measurement procedure for evaluating the use of NGS for whole-genome HIV-1. Sequencing analyzer outputs were submitted to a downstream CE-IVD standalone software tailored for HIV-1 analysis and interpretation.

RESULTS

The limits of range detection were 1000 to 10⁶ cp/mL for the HIV-1 target-specific sequencing. The median coverage per sample for the three amplicons (PR/RT and INT) was 13,237 reads. High analytical reproducibility and repeatability were evidenced by a positive percent agreement of 100%. Duplicated samples in two distinct NGS runs were 100% homologous. NGS detected all the mutations found by capillary electrophoresis and identified additional resistance variants. A perfect accuracy score with the QCMD panel detection of drug-resistance mutations was obtained.

CONCLUSIONS

This study is the first evaluation of the DeepChek^® Assays for targets specific (PR/RT and INT) and whole genome. A cutoff of 3% allowed for a better characterization of the viral population by identifying additional resistance mutations and improving the HIV-1 drug-resistance interpretation. The use of whole-genome sequencing is an additional and complementary tool to detect mutations in newly infected untreated patients and heavily experienced patients, both with higher HIV-1 viral-load profiles, to offer new insight and treatment strategies, especially using the new HIV-1 capsid/maturation inhibitors and to assess the potential clinical impact of mutations in the HIV-1 genome outside of the usual HIV-1 targets (RT/PR and INT).

Trends in Quantification of HbA1c Using Electrochemical and Point-of-Care Analyzers

Glycated hemoglobin (HbA1c), one of the many variants of hemoglobin (Hb), serves as a standard biomarker of diabetes, as it assesses the long-term glycemic status of the individual for the previous 90-120 days. HbA1c levels in blood are stable and do not fluctuate when compared to the random blood glucose levels. The normal level of HbA1c is 4-6.0%, while concentrations > 6.5% denote diabetes. Conventionally, HbA1c is measured using techniques such as chromatography, spectroscopy, immunoassays, capillary electrophoresis, fluorometry, etc., that are time-consuming, expensive, and involve complex procedures and skilled personnel. These limitations have spurred development of sensors incorporating nanostructured materials that can aid in specific and accurate quantification of HbA1c. Various chemical and biological sensing elements with and without nanoparticle interfaces have been explored for HbA1c detection. Attempts are underway to improve the detection speed, increase accuracy, and reduce sample volumes and detection costs through different combinations of nanomaterials, interfaces, capture elements, and measurement techniques. This review elaborates on the recent advances in the realm of electrochemical detection for HbA1c detection. It also discusses the emerging trends and challenges in the fabrication of effective, accurate, and cost-effective point-of-care (PoC) devices for HbA1c and the potential way forward.

Analysis of Denosumab by a Validated CZE Method and Determination of Sialic Acids by the RP-HPLC Method

A capillary zone electrophoresis (CZE) method was developed and validated to quantitate the monoclonal antibody denosumab (DmAb) and its charge variants in pharmaceutical products, demonstrating excellent precision, linearity and accuracy. Separations were obtained with migration times of 11.3 min for DmAb and the calibration curve was linear in the range of 0.95-20 mg/mL. The analytical comparability of seven batches of Prolia® showed mean differences of the estimated content/potencies of 1.87% lower, and 0.84 and 1.21% higher compared with the size-exclusion and reversed-phase liquid chromatography (SE-HPLC and RP-HPLC) methods and the osteoclast antiproliferative bioassay, respectively, with non-significant differences (P > 0.05). An RP-HPLC method with fluorescence detection (RP-HPLC-F), performed on a Kinetex® EVO C18 column (5 μm, 100 Å, 250 mm × 4.6 mm), was optimized to determine the levels of sialic acids of DmAb biomolecules, giving mean concentrations of 0.16 and 0.17 μg N-acetylneuraminic acid/mg DmAb for Prolia® and Xgeva® pharmaceutical products, respectively. The results demonstrated the capability of each one of the methods, and their use in combination constitutes a strategy to monitor instability, thereby assuring the quality and the batch-to-batch consistency of the biotechnology-derived medicine.

Capillary gel electrophoresis of very high molecular weight glycoproteins. Commercial and tailor-made gels for analysis of human monomeric and secretory immunoglobulin A

Capillary gel electrophoresis (CGE) has been widely used for analysis of proteins according to their size. However, to our knowledge, this technique has not been optimized to immunoglobulin A (IgA) analysis, a protein of current and emerging high interest in several fields. IgA is the first barrier of human body against pathogens. This protein in human milk and colostrum is essential for immune protection of newborns and treatment of milk for storage in Human Milk Banks may alter IgA. The emerging use of IgA as therapeutic treatment also encourages the development of analysis methods for this class of immunoglobulins. IgA is far more heterogeneously glycosylated and complex than the well-studied IgG molecules. IgA in serum is mainly monomeric (mIgA) with about 160 kDa, while in secretions such as saliva, milk, colostrum, etc, secretory immunoglobulin A (sIgA) is the predominant form. This is a dimer where both monomers are linked by the J-chain and the secretory component accounting all together for a MW higher than 400 kDa including the glycans. This size is far from the 225 kDa MW for which commercial CGE kits are intended. The general rules governing CGE behavior of analytes cannot be directly applied to every protein. Addressing studies directed specifically to target proteins is specially needed for the large size and highly complex target analytes of this study. In this work the effect of several factors on CGE analysis of human serum and colostrum IgA is studied. The feasibility of performing analysis of both IgA classes using a commercial CGE kit is shown. In addition, this work introduces another novelty by preparing tailor-made reproducible gel buffers and to characterize them in terms of dynamic viscosity, conductivity, and electroosmotic flow mobility in bare fused silica capillaries. The possibility of analyzing mIgA and sIgA in less than 10 min using these tailor-made gels is demonstrated. Inter-day variation (RSD) for the main peak of sIgA is 0.25% for migration time (tm) and 0.27% for percentage corrected peak area (Acorr).

Applications of Capillary Electrophoresis for the Determination of Cannabinoids in Different Matrices

Cannabinoids, terpenophenolic chemicals found only in cannabis, are primarily responsible for cannabis pharmacologic effects; nearly 150 distinct cannabinoids have been identified thus far. Among these, the main psychoactive molecule, tetrahydrocannabinol (THC), and the non-psychoactive counterpart, cannabidiol (CBD) are distinguishable. In the past decade, a CBD-containing pharmaceutical preparation was approved by Food and Drug Administration (FDA) for the treatment of drug-resistant epileptic seizures in children, and research trials for a variety of additional medical conditions for which CBD has been suggested as a therapy are being conducted. Additionally, the number of "CBD-containing" dietary supplements, largely available online, is increasing rapidly. Consequently, the necessity for the development of qualitative and quantitative methodologies for the analysis of the bioactive components of Cannabis is rising because of the increase in the production of therapeutic cannabis products. One of the analytical methods with good potential in cannabinoids analysis is capillary electrophoresis (CE). It has advantages related to high separation efficiency, relatively short analysis time, and the small consumption of analytes and reagents which generates relatively lower operational costs than other methods. This review focuses on the use of CE techniques to examine biological matrices and plant materials for the presence of cannabinoids and other bioactive compounds found in cannabis. The advantages, drawbacks, and applicability of the various electromigration approaches are also assessed. The article provides an overview of the "state of the art" and the latest trends in CE-based methods for the determination of cannabinoids.

Capillary Electrophoresis with Applied Biosystems' 3500 Genetic Analyzer

The Applied Biosystems® 3500/3500xL Genetic Analyzer is a capillary electrophoresis system used to perform fragment analysis of forensic samples (Thermo Fisher Scientific, Applied Biosystems 3500/3500xL Genetic Analyzer User Guide, Revision C, 2010). In this chapter, a procedure is described that details how to load reagents, set up the software, and prepare and process a sample plate.

Fluorescence-Based Analyses of Poly(ADP-Ribose) Length by Gel Electrophoresis, High-Performance Liquid Chromatography, and Capillary Electrophoresis

Poly(ADP-ribose) (PAR) is a homopolymer made of two or more adenosine diphosphate ribose (ADP-ribose) units. The polymer is usually conjugated to protein as a posttranslational modification playing key roles in cellular processes, such as DNA repair, RNA metabolism, and biomolecular condensate formation. Emergent data revealed that PAR length is highly regulated and determines the selection of and affinity towards protein binders. Here, we describe several fluorescence-based methods that quantify PAR length distributions. Briefly, we use the bioconjugation technique ELTA (enzymatic labeling of terminal ADP-ribose) to fluorescently label PAR, which can be isolated from in vitro and cellular samples. We describe a novel capillary electrophoresis method to separate and quantify PAR length and compare the profile to gel electrophoresis- and high-performance liquid chromatography-based methods. The capillary electrophoresis method is rapid and automatable, enabling accurate determination of the length profiles from subfemtomole quantities of PAR.

An Improved Isotope Labelling Method for Quantifying Deamidated Cobratide Using High-Resolution Quadrupole-Orbitrap Mass Spectrometry

Protein deamidation can severely alter the physicochemical characteristics and biological functions of protein therapeutics. Cobratide is a non-addictive analgesic with wide clinical acceptance. However, the Asn residue at position 48 from the N-terminus of the cobratide amino acid sequence (N48) tends to degrade during purification, storage, and transport. This characteristic could severely affect the drug safety and clinical efficacy of cobratide. Traditional methods for quantitating deamidation reported in previous research are characterised by low efficiency and accuracy; the quality control of cobratide via this method is limited. Herein, we developed an improved 18O-labelling method based on the detection of a unique peptide (i.e., the protein fragment of cobratide containing the N48 deamidation hotspot after enzymolysis) using an Orbitrap high-resolution mass spectrometer to quantify deamidated cobratide. The limits of detection and quantification of this method reached 0.02 and 0.025 μM, respectively, and inter- and intra-day precision values of the method were <3%. The accuracy of the 18O-labelling strategy was validated by using samples containing synthesised peptides with a known ratio of deamidation impurities and also by comparing the final total deamidation results with our previously developed capillary electrophoresis method. The recoveries for deamidation (Asp), deamidation isomerisation (iso-Asp), and total deamidation were 101.52 ± 1.17, 102.42 ± 1.82, and 103.55 ± 1.07, respectively. The robustness of the method was confirmed by verifying the chromatographic parameters. Our results demonstrate the applicability of the 18O-labelling strategy for detecting protein deamidation and lay a robust foundation for protein therapeutics studies and drug quality consistency evaluations.

Affinity capillary electrophoresis – mass spectrometry permits direct binding assessment of IgG and FcγRIIa in a glycoform-resolved manner

The impact of antibody glycoforms on FcγRIIa activation and immune responses is poorly understood. Yet, glycoform binding assessment remains one of the major analytical challenges requiring long enrichment or glycoengineering steps. Here, we developed and applied an affinity capillary electrophoresis-mass spectrometry approach to selectively assess the binding of different antibody glycoforms to the FcγIIa receptor without the need of glycoengineering. The approach required only low microgram amounts of antibody and receptor and enables assessing the binding of high and low-abundance glycoforms. The approach indicated clear differences in binging between doubly-, hemi-glycosylated and non-glycosylated antibodies as well as for mutated (Leu234Ala, Leu235Ala – Pro329-Gly (LALA-PG)) IgG1 antibodies silenced for Fcγ binding. The LALA-PG mutated antibody showed no binding to the FcγIIa receptor (excluding potential non-specific binding effects) while the non-glycosylated IgG1 showed a strongly reduced, but still minor binding. The highest binding affinity was for the antibody carrying two complex-type glycans. Man5 glycans resulted in decreased binding compared to complex-type glycans, with the lowest binding for the IgG containing two Man5. For complex-type glycans, galactosylation showed a subtle increase in binding to the FcγIIa receptor, and sialylation showed an increase in binding for lower sialylated species. Fucosylation did not influence binding to the FcγIIa receptor. Finally, the assay was evaluated for the two variants of the FcγRIIa receptor (allotypes H131 and R131) showing highly comparable glycoform selectivity. Overall, the proposed approach allows the direct comparison of binding affinities of different antibody species in mixtures promising a fast establishment of their structure-function relationships.

A chemometric experimental design with three-step stacking capillary electrophoresis for analysis of five tobacco-specific nitrosamines in cigarette products

Tobacco-specific nitrosamines (TSNAs) as carcinogens endanger our health and life from cigarette products. However, the safe range of TSNAs levels in commercial cigarette products has not yet been established. For the purpose of safety and supervision, a three-step stacking approach including field amplified sample injection (FASI), sweeping, and analyte focusing by micelle collapse (AFMC), was developed for the simultaneous determination of five TSNAs levels in cigarette products. This approach also involved aspects of chemometric experimental design, including fractional factorial design and central composite design. After the multilevel optimization of the experimental design, the five TSNAs were well separated. The LOD (S/N = 3) values of the N´-nitrosonornicotine (NNN), N´-nitrosoanatabine (NAT), N´-nitrosoanabasine (NAB), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in the FASI-sweeping-AFMC CE approach were 1.000 ng/mL, 0.500 ng/mL, 0.125 ng/mL, 1.000 ng/mL, and 0.500 ng/mL respectively. The results of relative standard deviation (RSD) and relative error (RE) were all less than 3.35%, demonstrating good precision and accuracy. Finally, this novel approach was further applied to monitor three commercial cigarette products, and a range of 250.1-336.6 ng/g for NNN, 481.6-526.7 ng/g for NAT, 82.2-247.6 ng/g for NAB, 167.7-473.7 ng/g for NNAL, and 39.4-246.7 ng/g for NNK could be observed among these. Based on these results, the novel CE stacking strategy was successfully applied for the analysis of five TSNAs levels in cigarette products and could serve as a tool for assays of quality control of nitrosamines.