Dried Blood Spots: Analysis and Applications

Simultaneous monitoring of seven antiepileptic drugs by dried blood spot and dried plasma spot sampling: method validation and clinical application of a LC-MS/MS-based technique

Alternative blood sampling strategy can enhance the application of therapeutic drug monitoring (TDM), then improve precision therapy and medication compliance. In developing nations, alternative sampling strategy that allows self-sampling and room temperature transport is especially important. This study validates the use of dried blood spot (DBS) and dried plasma spot (DPS) sampling along with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for analyzing seven common antiepileptic drugs (AEDs) (phenytoin, lamotrigine, levetiracetam, topiramate, carbamazepine, oxcarbazepine and its active metabolite 10,11-dihydro-10-hydroxy carbamazepine) and evaluates their applicability to clinical practice. Following simple protein precipitation with acetonitrile, the AEDs were separated on a C18 column by gradient elution with a mobile phase consisting of acetonitrile-water-0.1% formic acid at a flow rate of 0.65 mL/min. The method provided linear analysis over the tested concentration ranges, with a total run time of 7 min. Intra- and inter-assay precision for all quality controls were ≤12% with accuracies of 85.9%-113%. The average extraction efficiencies were 69.0%-92.4% for DBS and 65.9%-96.5% for DPS, and no significant matrix effects were observed. The AEDs were stable in all samples for seven days at room temprature and 40°C. There was good correlation between the dry and wet plasma concentrations with greater accuracy for DPS compared to DBS indicating that alternative sampling strategy using DBS and DPS are suitable for monitoring the concentrations of AEDs with satisfied performance and logistical advantages.

Nucleic acid degradation after long-term dried blood spot storage

Collecting and preserving biological samples in the field, particularly in remote areas in tropical forests, prior to laboratory analysis is challenging. Blood samples in many cases are used for nucleic acid-based species determination, genomics or pathogen research. In most cases, maintaining a cold chain is impossible and samples remain at ambient temperature for extended periods of time before controlled storage conditions become available. Dried blood spot (DBS) storage, blood stored on cellulose-based paper, has been widely applied to facilitate sample collection and preservation in the field for decades. However, it is unclear how long-term storage on this substrate affects nucleic acid concentration and integrity. We analysed nucleic acid quality from DBS stored on Whatman filter paper no. 3 and FTA cards for up to 15 years in comparison to cold-chain stored samples using four nucleic acid extraction methods. We examined the ability to identify viral sequences from samples of 12 free-ranging primates in the Amazon forest, using targeted hybridization capture, and determined if mitochondrial genomes could be retrieved. The results suggest that even after extended periods of storage, DBS will be suitable for some genomic applications but may be of limited use for viral pathogen research, particularly RNA viruses.

Dried Blood Spots and Miniaturized Ultrasonic Nebulization Microplasma Optical Emission Spectrometry for Point-of-Care Testing of Blood Lithium

Despite the significant importance of blood lithium (Li) detection in the treatment of bipolar disorder (BD), its point-of-care testing (POCT) remains a great challenge due to tedious sample preparation and the use of large-footprint atomic spectrometers. Herein, a system coupling dried blood spots (DBS) with a point discharge optical emission spectrometer equipped with a miniaturized ultrasonic nebulizer (MUN-μPD-OES) was developed for POCT of blood Li. Three microliters of whole blood were used to prepare a dried blood spot on a piece of filter paper to which 10 μL of eluent (1% (v/v) formic acid and 0.05% (v/v) Triton-X) was added. Subsequently, the paper was placed onto the vibrating steel membrane of the ultrasonic nebulizer and powered on to generate aerosol. The aerosol was directly introduced to the μPD-OES for quantification of Li by monitoring its atomic emission line at 670.8 nm. The proposed method minimized matrix interference caused by high levels of salts and protein. It is worth noting that the MUN suitably matches the needs of DBS sampling and can provide aerosolized introduction of Li into the assembled μPD-OES, thus eliminating all tedious sample preparation and the need for a commercial atomic spectrometer. Calibration response is linear in the therapeutic range and a limit of detection (LOD) of 1.3 μg L-1 is well below the Li minimum therapeutic concentration (2800 μg L-1). Li in mouse blood was successfully detected in real-time using MUN-μPD-OES after intraperitoneal injection of lithium carbonate, confirming that the system holds great potential for POCT of blood Li for patients with BD.

The role of estrogen receptor gene polymorphisms in menopausal symptoms and estradiol levels in perimenopausal women - Findings from the Swiss Perimenopause Study

OBJECTIVES

Fluctuating estradiol (E2) levels seem to be associated with menopausal symptoms, though not all women suffer from these symptoms to the same extent despite experiencing these hormonal changes. This suggests underlying, interindividual mechanisms, such as single-nucleotide polymorphisms (SNPs) influencing estrogen receptors α and β, and the g-protein-coupled estrogen receptor (GPER). As research is scarce, we aimed to address this research gap by assessing genetic traits, E2 levels, and menopausal symptoms longitudinally.

STUDY DESIGN

129 perimenopausal women (aged 40-56 years) participated in the 13-month longitudinal Swiss Perimenopause Study.

MAIN OUTCOME MEASURES

Menopausal symptoms were assessed fortnightly using the Menopause Rating Scale (MRS II). Salivary E2 levels were assessed 14 times over two non-consecutive months. Blood samples were collected using the dried blood spot (DBS) technique to analyze ESR1 rs2234693, ESR1 rs9340799, ESR2 rs1256049, ESR2 rs4906938, and GPER rs3808350. Group-based trajectory modeling was performed to identify interindividual trajectories of menopausal symptoms. Multinomial logistic regression models were employed to identify factors associated with these trajectories.

RESULTS

Four distinct trajectory groups of menopausal symptoms were identified (increase, moderate, rebound, decrease). ER gene polymorphisms and E2 fluctuation were significantly associated with group membership. Furthermore, ER gene polymorphisms modulated the effect of E2 fluctuations on menopausal symptom trajectory.

CONCLUSIONS

This study illuminates the multifaceted factors contributing to the individuality of the perimenopausal experience. ER gene polymorphisms emerged as integral factors by modulating the effect of E2 fluctuations on menopausal symptom trajectory. This underscores the intricate interplay of genetic factors, E2 fluctuations, and menopausal symptoms during perimenopause.

Insight into Increased Recovery and Simplification of Genomic DNA Extraction Methods from Dried Blood Spots

There is no consensus on how to perform the manual extraction of nucleic acids from dried blood spots (DBSs). Current methods typically involve agitation of the DBSs in a solution for varying amounts of time with or without heat, and then purification of the eluted nucleic acids with a purification protocol. We explored several characteristics of genomic DNA (gDNA) DBS extraction such as extraction efficiency, the role of red blood cells (RBCs) in extraction and critical kinetic factors to understand if these protocols can be simplified while maintaining sufficient gDNA recovery. We found that agitation in a RBC lysis buffer before performing a DBS gDNA extraction protocol increases yield 1.5 to 5-fold, depending upon the anticoagulant used. The use of an alkaline lysing agent along with either heat or agitation was sufficient to elute quantitative polymerase chain reaction (qPCR) amplifiable gDNA in 5 minutes. This work adds insight into the extraction of gDNA from DBSs with the intention of informing a simple, standardized manual protocol for extraction.

Discrimination of blood metabolomics profiles in neonates with idiopathic polyhydramnios

This study aimed to compare the blood metabolic status of neonates with idiopathic polyhydramnios (IPH) and those with normal amniotic fluid, and to explore the relationship between IPH and fetal health. Blood metabolites of 32 patients with IPH and 32 normal controls admitted to the Sixth Affiliated Hospital of Sun Yat-sen University between January 2017 and December 2022 were analyzed using liquid chromatography-mass spectrometry (LC-MS/MS). Orthogonal partial least squares discriminant analysis (OPLS-DA) and metabolite enrichment analyses were performed to identify the differential metabolites and metabolic pathways. There was a significant difference in the blood metabolism between newborns with IPH and those with normal amniotic fluid. Six discriminant metabolites were identified: glutamate, serine, asparagine, aspartic acid, homocysteine, and phenylalanine. Differential metabolites were mainly enriched in two pathways: aminoacyl-tRNA biosynthesis, and alanine, aspartate, and glutamate metabolism.

CONCLUSIONS

This study is the first to investigate metabolomic profiles in newborns with IPH and examine the correlation between IPH and fetal health. Differential metabolites and pathways may affect amino acid synthesis and the nervous system. Continuous attention to the development of the nervous system in children with IPH is necessary.

WHAT IS KNOWN

• There is an increased risk of adverse pregnancy outcomes with IPH, such as perinatal death, neonatal asphyxia, neonatal intensive care admission, cesarean section rates, and postpartum hemorrhage. • Children with a history of IPH have a higher proportion of defects than the general population, particularly central nervous system problems, neuromuscular disorders, and other malformations.

WHAT IS NEW

• In neonates with IPH, six differential metabolites were identified with significant differences and good AUC values using LC-MS/MS analysis: glutamic acid, serine, asparagine, aspartic acid, homocysteine, and phenylalanine, which were mainly enriched in two metabolic pathways: aminoacyl-tRNA biosynthesis and alanine, aspartate, and glutamate metabolism. • These differential metabolites and pathways may affect amino acid synthesis and development of the nervous system in neonates with IPH.

A feasible protocol to profile bile acids in dried blood spots from rats using a UHPLC-MS/MS method combining a surrogate matrix

Dried blood spot (DBS) sampling is a promising method for microliter blood sample collection with the advantages of convenient transportation, storage and clinical operations. However, it is challenging to develop an analytical protocol to determine endogenous metabolites, such as bile acids (BAs) in DBSs, due to the low-blood-volume character of DBSs and the complex features of filter paper. Herein, we developed a method of fast ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) to profile and quantify BAs in DBSs. The pretreatment methods were optimized and a two-step solvent addition method, where a small amount of water was firstly added to moisten the DBS and then methanol was added, showed high extraction efficiency for multiple BAs in DBSs. The UHPLC-MS/MS conditions were optimized and 35BAs in different types could be profiled with good resolution and quantified with acceptable precision and accuracy. Preparation of a DBS surrogate matrix without endogenous BAs has been well developed using rat erythrocytes in BSA solution and showed good performance on both the signal suppression/enhancement percentage and parallelism assessment evaluation of three different stable-isotope-labeled (SIL) BAs. The established protocol was successfully applied to profile BAs in DBSs of intrahepatic cholestasis model and healthy control rats with good repeatability. To our knowledge, it is the first time that 35 BAs in DBSs could be well profiled and an appropriate DBS surrogate matrix has been developed. This protocol presents future-oriented applications of DBSs for relevant preclinical studies to profile BAs and probe biomarkers.

Dried Blood Spots (DBS): A suitable alternative to using whole blood samples for diagnostic testing of visceral leishmaniasis in the post-elimination era

BACKGROUND

Serum or whole blood collection, processing, transport and storage still present significant challenges in low resource settings where mass surveillance is required to sustain disease elimination. Therefore, in this study, we explored the diagnostic efficacy of dried blood spots (DBS) as a minimally invasive and potentially cost-effective alternative sampling technique to whole blood sampling procedures for subsequent detection of Leishmania donovani antibodies or DNA.

METHODOLOGY AND PRINCIPAL FINDINGS

Archived serum, DNA samples from whole blood of visceral leishmaniasis (VL) cases and healthy controls, and DBS from corresponding cases and controls, were used. Both molecular and serological assays were optimized to detect L. donovani antibodies or DNA in DBS elute and results were compared against those obtained with whole blood. Serological assays (both rK28 ELISA and rK39 ELISA) of DBS samples showed sensitivity and specificity of 100% and had excellent agreement with results from whole blood samples (kappa value ranged from 0.98-1). Bland-Altman analysis of OD values from rK28-ELISA with DBS elute and patients' serum showed an excellent agreement (ICC = 0.9) whereas a good agreement (ICC = 0.8) was observed in the case of rK39-ELISA. However, qPCR and RPA of DBS samples had a diminished sensitivity of 76% and 68%, respectively, and poor agreement was observed with the whole blood samples.

CONCLUSION

Our results demonstrate that DBS offer excellent diagnostic efficiency for serological assays and represent a viable alternative to whole blood sampling procedures.

Important Lessons on Long-Term Stability of Amino Acids in Stored Dried Blood Spots

Residual heel prick Dried Blood Spots (DBS) are valuable samples for retrospective investigation of inborn metabolic diseases (IMD) and biomarker analyses. Because many metabolites suffer time-dependent decay, we investigated the five-year stability of amino acids (AA) in residual heel prick DBS. In 2019/2020, we analyzed 23 AAs in 2170 residual heel prick DBS from the Dutch neonatal screening program, stored from 2013-2017 (one year at +4 °C and four years at room temperature), using liquid chromatography mass-spectrometry. Stability was assessed by AA changes over the five years. Hydroxyproline could not be measured accurately and was not further assessed. Concentrations of 19 out of the remaining 22 AAs degraded significantly, ranked from most to least stable: aspartate, isoleucine, proline, valine, leucine, tyrosine, alanine, phenylalanine, threonine, citrulline, glutamate, serine, ornithine, glycine, asparagine, lysine, taurine, tryptophan and glutamine. Arginine, histidine and methionine concentrations were below the limit of detection and were likely to have been degraded within the first year of storage. AAs in residual heel prick DBS stored at room temperature are subject to substantial degradation, which may cause incorrect interpretation of test results for retrospective biomarker studies and IMD diagnostics. Therefore, retrospective analysis of heel prick blood should be done in comparison to similarly stored heel prick blood from controls.

Safety of medicines during breastfeeding - from case report to modeling : A contribution from the ConcePTION project

INTRODUCTION

Despite many research efforts, current data on the safety of medicines during breastfeeding are either fragmented or lacking, resulting in restrictive labeling of most medicines. In the absence of pharmacoepidemiologic safety studies, risk estimation for breastfed infants is mainly derived from pharmacokinetic (PK) information on the medicine. This manuscript provides a description and a comparison of the different methodological approaches that can yield reliable information on medicine transfer into human milk and the resulting infant exposure.

AREA COVERED

Currently, most information on medicine transfer in human milk relies on case reports or traditional PK studies, which generate data that can hardly be generalized to the population. Some methodological approaches, such as population PK (popPK) and physiologically-based PK (PBPK) modeling, can be used to provide a more complete characterization of infant medicine exposure through human milk and simulate the most extreme situations, while decreasing the burden of sampling in breastfeeding women.

EXPERT OPINION

PBPK and popPK modeling are promising approaches to fill the gap of knowledge in medicine safety in breastfeeding, as illustrated with our escitalopram example.

Digital and Absolute Assays for Low Abundance Molecular Biomarkers

There has been a recent surge of advances in biomolecular assays based on the measurement of discrete molecular targets as opposed to signals averaged across molecular ensembles. Many of these "digital" assay designs derive from now-mature technologies involving single-molecule imaging and microfluidics and provide an assortment of new modalities to quantify nucleic acids and proteins in biospecimens such as blood and tissue homogenates. A primary new benefit is the robust detection of trace analytes at attomolar to femtomolar concentrations for which many ensemble assays cannot distinguish signals above noise levels. In addition, multiple biomolecules can be differentiated within a mixture using optical barcodes, with much faster and simpler readouts compared with sequencing methods. In ideal digital assays, signals should, in theory, further represent absolute molecular counts, rather than relative levels, eliminating the need for calibration standards that are the mainstay of typical assays. Several digital assay platforms have now been commercialized but challenges hinder the adoption and diversification of these new formats, as there are broad needs to balance sensitivity and dynamic range of detection, increase analyte multiplexing, improve sample throughput, and reduce cost. Our lab and others have developed technologies to address these challenges by redesigning molecular probes and labels, improving molecular transport within detection focal volumes, and applying solution-based readout methods in flow.This Account describes the principles, formats, and design constraints of digital biomolecular assays that apply optical labels toward the goal of simple and routine target counting that may ultimately approach absolute readout standards. The primary challenges can be understood from fundamental concepts in thermodynamics and kinetics of association reactions, mass transport, and discrete statistics. Major advances include (1) new inorganic nanocrystal probes for more robust counting compared with dyes, (2) diverse molecular amplification tools that endow attachment of numerous labels to single targets, (3) specialized surfaces with patterned features for electromagnetic coupling to labels for signal amplification, (4) surface capture enhancement methods to concentrate targets through disruption of diffusion depletion zones, and (5) flow counting in which analytes are rapidly counted in solution without pull-down to a surface. Further progress and integration of these tools for biomolecular counting could improve the precision of laboratory measurements in life sciences research and benefit clinical diagnostic assays for low abundance biomarkers in limiting biospecimen volumes that are out of reach of traditional ensemble-level bioassays.

Ceramides biomarkers determination in quantitative dried blood spots by UHPLC-MS/MS

A method was developed for the analysis of four ceramide species; namely C16:0, C18:0, C24:0 and C24:1 in quantitative Dried Blood Samples (qDBS) by LC-MS/MS and validated with the aim to give prominence to an interesting application of at-home blood microsampling for health monitoring. Ceramides, being key-role metabolites implicated in regulation of diverse cellular processes have been considered as emerging biomarkers for different disease states, such as cardiovascular diseases, type 2 diabetes and others. Here, Capitainer device was utilized to provide accurate and consistent volumes of samples, ideal for accurate determinations. The method requires a 10 μL sample offering duplicate analysis by device, is quick and enables the sample collection by distance as it was proved that ceramides under study were stable at various conditions, including RT. Intra and inter-day accuracy of the determination were estimated between 87.6% - 113% and 90.6% -113%, respectively, while intra- and inter-day precision were calculated from 0.2% to 9.9% %RSD and 0.1% - 8.0% %RSD, respectively. The data acquired by ten healthy individuals indicated that circulating ceramides are at higher levels in whole blood taken from the fingertip in comparison to the reported values in plasma or serum.

A thread-based electrofluidic platform for direct transfer, separation, and pre-concentration of materials from sample swabs

A new method and platform has been developed for direct transfer, electrophoretic separation, and pre-concentration of swabbed samples using the principles of thread-based electrofluidics. A direct electrokinetic injection has been observed for a variety of analytes ranging from small molecules to proteins. The effect of physicochemical interactions of the analyte with the swab and the thread on the transfer efficiency has been studied by exploring different swab and thread combinations. For fluorescein, using a polyurethane swab, 98% and 94% transfer efficiencies were observed on mercerised cotton and nylon thread, while only 80% transfer efficiency was observed on polyester thread, respectively. A 97% transfer of fluorescein was observed on the nylon thread when a flocked nylon swab was used, while only 47% transfer was observed when a cotton swab was used. A successful transfer has been observed for both liquid and dry samples from either pre-wetted or dry swabs in both the presence and absence of any surrounding electrolytes. The platform has been further adapted for multiplexed analysis, where a sample from a single swab was transferred onto two parallel thread systems with ca. 50% distribution between them. The method has been validated for transfer, separation, and pre-concentration of DNA from blood. It has also been successfully used to directly analyse dried blood samples using a commercial sampling device, Neoteryx Mitra.

Exploring the potential of dried plasma collection cards for liquid chromatography coupled with tandem mass spectrometry quantitation of giredestrant in human plasma

Microsampling technology for dried blood-derived samples provides an advantageous alternative to conventional venous blood for drug quantitation. Unlike conventional whole blood microsampling techniques, Noviplex is a novel, card-based technology for rapid dried plasma spot collection that retains the benefits of microsampling during collection and transportation, while avoiding the disadvantages of using whole blood samples. Giredestrant is a promising small-molecule therapeutic agent under development by Genentech to treat patients with estrogen receptor-positive breast cancer. In this study, we investigated the feasibility of using Noviplex cards for pharmacokinetic analysis of giredestrant levels in human plasma, including optimizing extraction recovery, evaluating in-card stability, and assessing batch precision and accuracy. We found that while the Noviplex card demonstrated levels of sensitivity, extraction recovery, and stability at ambient temperature that meet the requirements of pharmacokinetic analysis for clinical studies, further optimization of the filtration layers within the Noviplex card is necessary to improve filtration efficiency and consistency. This study reveals the possibilities as well as the limitations of the Noviplex card and provides a better understanding of the capabilities and risks of using the Noviplex card for drug quantitation in plasma.

Rapid quantitation of SARS-CoV-2 antibodies in clinical samples with an electrochemical sensor

The current coronavirus disease 2019 (COVID-19) pandemic is caused by several variants of severe acute respiratory syndrome coronavirus-2 virus (SARS-CoV-2). With the roll-out of vaccines and development of new therapeutics that may be targeted to distinct viral molecules, there is a need to screen populations for viral antigen-specific SARS-CoV-2 antibodies. Here, we report a rapid, multiplexed, electrochemical (EC) device with on-chip control that enables detection of SARS-CoV-2 antibodies in less than 10 min using 1.5 μL of a patient sample. The EC biosensor demonstrated 100% sensitivity and specificity, and an area under the receiver operating characteristic curve of 1, when evaluated using 93 clinical samples, including plasma and dried blood spot samples from 54 SARS-CoV-2 positive and 39 negative patients. This EC biosensor platform enables simple, cost-effective, sensitive, and rapid detection of anti-SARS-CoV-2 antibodies in complex clinical samples, which is convenient for evaluating humoral-responses to vaccination or infection in population-wide testing, including applications in point-of-care settings. We also demonstrate the feasibility of using dried blood spot samples that can be collected locally and transported to distant clinical laboratories at ambient temperature for detection of anti-SARS-CoV-2 antibodies which may be utilized for serological surveillance and demonstrate the utility of remote sampling.

Surface sampling capillary electrophoresis-mass spectrometry for a direct chemical characterization of tissue and blood samples

Capillary electrophoresis (CE) is a powerful separation tool for non-targeted analysis of chemically complex samples, such as blood, urine, and tissue. However, traditionally CE requires samples in solution for analysis, which limits information on analyte distribution and heterogeneity in tissue. The recent development of surface sampling CE-mass spectrometry (SS-CE-MS) brings these advantages of CE to solid samples and enables chemical mapping directly from the tissue surface without laborious sample preparation. Here, we describe developments of SS-CE-MS to increase reproducibility and stability for metabolite, lipid, and protein extraction from tissue sections and dried blood spots. Additionally, we report the first electrokinetic sequential sample injection for high throughput analysis. We foresee that the wide molecular coverage from a distinct tissue region in combination with higher throughput will provide novel information on biological function and dysfunction.

Development of the dried blood spot preparation protocol for comprehensive evaluation of the hematocrit effect

The application of dried blood spots (DBS) has gradually increased in different fields because of its several advantages. The hematocrit (Hct) effect is one major analytical challenge that may affect the quantification accuracy of DBS samples and should be investigated when developing a novel DBS method. However, previous studies usually overlooked the Hct-related distribution bias when evaluating the Hct effect. This study aimed to propose an effective DBS preparation protocol for the comprehensive evaluation of the Hct effect. We selected voriconazole and posaconazole as the demonstration drugs. Fifteen microliters of the blood samples were spotted on DBS cards followed by whole spot extraction. An LC-MS/MS method was first developed to quantify voriconazole and posaconazole in DBS samples. The quantitation accuracy for both azole drugs was within 93.5%-111.7%, except for the accuracies of posaconazole at the LLOQ, which were less than 119%. The intra- and interday precision were below 11%. The validated LC-MS/MS method was used to develop the DBS preparation protocol for evaluating the Hct effect. Three critical parameters that may affect the observed Hct effect were investigated. The results showed that using the solid-state of the target analytes, spiking the target analytes before preparing different Hct levels, and allowing enough equilibrium time after spiking target analytes can provide a more holistic Hct effect evaluation. The validity of the proposed new protocol was verified by conversion factors obtained from 71 paired DBS and plasma samples. Conversion factors calculated by clinical samples were consistent with the Hct effect evaluated by manually prepared DBS samples. This new DBS preparation protocol eliminated the common pitfalls in studying the Hct effect and offered a comprehensive strategy to assess the Hct effect for further DBS studies.

Fully automated dried blood spot sample handling and extraction for BoHV-1 antibody testing by ELISA

This study is the first proof of concept of the DBS technology for Bovine alphaherpesvirus 1 (BoHV-1) antibody detection by ELISA after fully automated DBS extraction. DBS were prepared from nine BoHV-1 seropositive plasma samples spiked with erythrocytes. Spots were extracted automatically on a DBS-MS 500 HCT autosampler, as well as manually using a 3.2 mm puncher. DBS were equally prepared from 20 bovine seronegative EDTA-blood samples and extracted automatically. Extracts were tested in a commercial BoHV-1 antibody ELISA and results were compared with those from liquid plasma. Eight seropositive DBS samples were additionally tested in the ELISA after storage for four weeks at different conditions. After automated extraction all DBS samples yielded qualitatively correct results and were in full accordance with those obtained from liquid plasma. Automated extraction using a 6 mm extraction head was more sensitive than a 4 mm head. Stability of DBS was highest at - 20 °C and decreased with increasing temperature. Even after four weeks at 37 °C, most seropositive samples yielded a positive result in the ELISA. The minimal invasiveness, biosafety, and simplicity of DBS collection together with automated extraction represents an interesting, high-throughput compatible alternative to liquid blood samples for BoHV-1 monitoring or eradication programs.

Analysis of N7-(2-carbamoyl-2-hydroxyethyl)guanine in dried blood spot after food exposure by Ultra High Performance Liquid Chromatography-Tandem Mass Spectrometry

N⁷-(2-carbamoyl-2-hydroxyethyl)guanine (N7-CAG) is a DNA adduct formed by glycidamide, which is the metabolite of acrylamide. Acrylamide can be found in foods containing reducing sugars and asparagine that are heated at high temperatures. Analysis of N7-CAG was performed in Dried Blood Spot (DBS) samples from 25 subjects of group test who consumed a lot of acrylamide-containing foods and 25 subjects of negative control group. This study aimed to determine whether there is a significant difference in the levels of N7-CAG between the two groups. DBS samples were extracted using the QIAamp DNA Mini Blood Kit and analyzed using Ultra High Performance Liquid Chromatography–Tandem Mass Spectrometry (UHPLC-MS/MS). Separation was performed using an Acquity UPLC BEH C₁₈ column (2.1 mm × 100 mm; 1.7 μm), eluted a flow rate of 0.1 ml/min under an isocratic of mobile phase of 0.1% formic acid and acetonitrile. The bioanalytical method of N7-CAG in DBS with allopurinol as the internal standard by using UHPLC-MS/MS has been validated. The calibration curve range of N7-CAG obtained was 10–300 ng/ml with a coefficient of correlation of 0.997. The results of the analysis on 25 test group subjects showed that the concentration of N7-CAG ranged from 1.87 to 23.71 ng/ml, while the 25 subjects in the negative group ranged from 1.18 to 8.47 ng/ml. The results of the Mann Whitney test showed that there was a significant difference in the levels of N7-CAG between the test group and the negative control group with p value less than 0.001.

ADAPTATION OF “DRIED BLOOD DROP” METHOD FOR THERAPEUTIC DRUG MONITORING

To control the concentration of drugs with a narrow therapeutic range, and to conduct effective and safe treatments, Therapeutic Drug Monitoring (TDM) is carried out. However, to date, the implementation of TDM is associated with various difficulties, for the solution of which more convenient and less invasive methods for collecting biological material are being developed.

The aim of the study was to develop protocols for the collection and storage of “dried blood spot” (DBS) samples, as well as protocols for the validation methods for the quantitative determination of drugs in whole blood, using this technology for subsequent therapeutic drug monitoring.

Materials and methods. To analyze a “dried blood spot” method in detail and to identify the characteristic features of taking and storing biosamples, a collection and analysis of scientific literature over the past 10 years has been conducted. The search for literature materials has been carried out from open and accessible sources located in the scientific libraries of institutions, in electronic databases and search engines: Elibrary, PubMed, Scopus, Cyberleninka, Medline, ScienceDirect, Web of Science, Google Scholar. Primary protocols for taking, storing and analyzing samples of the “dried blood drop” have been prepared. To obtain the adequate quality samples, the developed protocols have been tested and optimized at the stages of selection and storage. By high-performance liquid chromatography with mass spectrometric detection (HPLC-MS/MS), using a “dried blood drop” as a sample preparation, drug validation protocols have been optimized to ensure that acceptable validation characteristics were achieved, and subsequent Therapeutic Drug Monitoring was performed.

Results. The features of the collection, storage and analysis of the “dried blood spot” samples have been revealed. Such characteristics as a spot volume effect, a hematocrit effect, a droplet uniformity, which can affect the results of a quantitative HPLC-MS/MS analysis, have been determined. For a successful use of the new methods, appropriate protocols for taking samples of “dried blood spot” from the finger of adult patients and from the heel of newborns, as well as protocols for validating methods for the quantitative determination of drugs from these samples, have been developed.

Conclusion. The application of the “dried blood spot” method using newly developed protocols for taking, storing and analyzing biological samples, relieves the existing constraints in conducting TDM, and can later become a promising method for conducting preclinical and clinical studies.

Development of Certified Reference Material for Amino Acids in Dried Blood Spots and Accuracy Assessment of Disc Sampling

To achieve the measurement reliability of amino acids used as diagnostic markers in clinical fields, establishing a reference measurement system is required, in which certified reference materials (CRMs) are an essential step in the hierarchy of measurement traceability. This study describes the development of dried blood spot (DBS) CRMs for amino acid analysis with complete measurement traceability to the International System of Units (SI). Six essential amino acids—proline, valine, isoleucine, leucine, phenylalanine, and tyrosine—were analyzed using isotope-dilution liquid chromatography–mass spectrometry (ID-MS). For minimizing measurement bias and uncertainty overestimation, whole spots with 50 μL of whole blood were adopted in the certification. The between-spot homogeneities by whole spot sampling were lower than 2.1%. The relative expanded uncertainties of the six amino acids in the developed DBS CRMs were lower than 5.7% at 95% confidence. The certified values are traceable to SI through both gravimetric preparation and the primary method in certification, ID-MS. Comparison among DBS testing laboratories revealed discrepancies between the whole spot and disc sampling methods. The actual sampling volume was accurately estimated by weighing, which revealed the possibility of underestimation in routine DBS testing. The candidate CRMs can support the standardization of DBS testing for amino acids through the qualification and validation of many kinds of measurement procedures to compensate the measurement bias caused by matrix-specific sampling error.

C-reactive protein and telomerase reverse transcriptase (TERT) associate with chronic disease markers in a sample from low-income neighborhoods in Detroit, Michigan

Racial and ethnic minorities in economically deprived inner cities experience high rates of chronic diseases compared to neighborhoods with higher socioeconomic status (SES). However, these economically deprived populations are understudied in terms of biomarkers associated with chronic disease risk which include C-reactive protein (CRP), telomerase reverse transcriptase (TERT), and glycosylated hemoglobin (A1C). We examined relationships between CRP and TERT and chronic disease indicators (body mass index [BMI] and A1C) in two low-income, predominantly African American (AA) neighborhoods in Detroit, Michigan. Sixty-nine adults (43 females, 26 males, mean age 46 years [y], standard deviation [SD] ​= ​15.9) completed a health survey, anthropometry, and finger stick blood tests. A1C was measured using A1CNow test strips, and CRP and TERT levels were measured using enzyme-linked immunosorbent assay (ELISA) with samples extracted from dried blood spots. We examined CRP (mean ​= ​4.9, SD ​= ​3.1), TERT (mean ​= ​32.5, SD ​= ​15.1), and A1C (mean ​= ​5.4, SD ​= ​1.0) by BMI category. We fitted restricted maximum likelihood regression models to evaluate associations between CRP, TERT, BMI, and A1C, after adjustment for demographics and inclusion of a random effect for the neighborhood. In this predominantly AA sample (91%, 63/69), 68% had levels of CRP (means ​= ​4.8 ​mg/L, SD ​= ​3.0 for AAs; 6.4 ​mg/L, SD ​= ​3.9 for all others) indicative of chronic inflammation (CRP greater than 3 ​mg/L). BMI was significantly associated with CRP (p ​= ​0.004) and TERT (p ​= ​0.026). TERT levels indicate that being overweight is associated with markers of chromosome remodeling, suggestive of chronic disease. CRP followed a similar trend with overweight individuals having higher inflammation and risk of chronic disease. Our findings warrant further exploration of additional factors that may influence CRP and TERT. Furthermore, examining populations in a more ethnically and/or economically diverse, yet still high proportion minority, sample will fill a knowledge gap in this understudied field.

Dried Blood Spots technology for veterinary applications and biological investigations: technical aspects, retrospective analysis, ongoing status and future perspectives

Dried Blood Spots (DBS) technology has become a valuable tool in medical studies, however, in veterinary and biological research DBS technology applications are still limited. Up-to-date no review has comprehensively integrated all the evidence existing across the fields, technologies and animal species. In this paper we summarize the current applications of DBS technology in the mentioned areas, and provide a scope of different types of dried sample carriers (cellulose and non-cellulose), sampling devices, applicable methods for analyte extraction and detection. Mammals, birds, insects and other species are represented as the study objects. Besides the blood, the review considers a variety of specimens, such as milk, saliva, tissue samples and others. The main applications of dried samples highlighted in the review include epidemiological surveys and monitoring for infections agents or specific antibodies for disease/vaccination control in households and wildlife. Besides the genetic investigations, the paper describes detection of environmental contaminants, pregnancy diagnosis and many other useful applications of animal dried samples. The paper also analyses dried sample stability and storage conditions for antibodies, viruses and other substances. Finally, recent developments and future research for DBS technology in veterinary medicine and biological sciences are discussed.

On the spot immunocapture in targeted biomarker analysis using paper-bound streptavidin as anchor for biotinylated antibodies

The modification of an easily available resource like paper to circumvent expensive or intensive sample pretreatment could be the answer to sample analysis in resource-poor regions. Therefore, a novel on-paper device combining sample collection with affinity sample pretreatment is introduced here. Universal smart affinity samplers are produced by a simple KIO₄-mediated oxidation of cellulose, which functionalizes the paper. This is followed by immobilization of streptavidin. Streptavidin serves as a universal anchor for biotinylated antibodies, enabling simple preparation of tailor-made affinity samplers. The functionality of the device was tested using a model protein (human chorionic gonadotropin, hCG) and biotinylated anti-hCG antibodies for affinity capture. In a laboratory setting, the performance was demonstrated, and a 14-fold increase of target binding compared to binding without bmAb was achieved. The recovery of hCG captured with bmAb-treated samplers was determined to be 33% and comparable to previously described affinity capture approaches. Application of the smart affinity samplers to human serum containing hCG showed an R² of 0.98 (200–1000 pg mL⁻¹), precision of ≤ 9.1% RSD, and estimated limit of detection of 65 pg mL⁻¹. Although further optimization and validation are necessary prior to application to real samples in clinical settings, the potential of the device for use in determination of low abundant biomarkers in complex samples has been demonstrated.

Mercury biomonitoring in German adults using volumetric absorptive microsampling

Mercury (Hg) is a global pollutant and a danger to human health. Human biomonitoring of Hg using a dried blood matrix instead of venous blood sampling for exposure assessment is of growing interest. This study aims to develop, validate, and evaluate the application of volumetric absorptive microsampling (VAMS) for Hg biomonitoring in humans. Sampling, drying, and storage conditions were evaluated during method development. Storage in pre-cleaned glass vials after drying for 2 h in a desiccator ensured analyte stability for at least 4 weeks. Sixty-eight paired capillary VAMS and venous blood samples from volunteers in Munich, Germany, were used for method validation. Hg levels in VAMS and venous blood samples were determined by direct mercury analysis. The limits of detection and quantitation for VAMS were 0.18 and 0.61 µg/l, respectively. However, sensitivity could be improved by using two microsamples for analysis instead of one. Hg levels in VAMS samples correlated very well with Hg levels in venous blood samples (R² = 0.958). Furthermore, VAMS showed a high accuracy (median recovery: 117%) and precision (median relative standard deviation: 8.7%), especially for Hg concentrations above 1.0 µg/l. In fact, accuracy and precision of VAMS improved with increasing Hg concentrations. In conclusion, VAMS in combination with direct mercury analysis is an accurate and viable alternative for human biomonitoring of Hg.

Paper-based sample processing for the fast and direct MS analysis of multiple analytes from serum samples

The direct MS detection of amino acids obtained from serum was successfully demonstrated via a paper-based fast electrokinetic sample clean-up method.

Impact of smoking cannabidiol (CBD)-rich marijuana on driving ability

To investigate effects of smoking cannabidiol (CBD)-rich marijuana on driving ability and determine free CBD and Δ⁹-tetrahydrocannabinol (THC) concentrations in capillary blood samples, a randomised, double-blind, placebo-controlled, two-way crossover pilot study was conducted with 33 participants. Participants smoked a joint containing 500 mg of tobacco and either 500 mg of CBD-rich marijuana (16.6% total CBD; 0.9% total THC) or 500 mg of a placebo substance, then performed three different dimensions of the Vienna Test System TRAFFIC examining reaction time, behaviour under stress, and concentration performance. For further assessment of participants' fitness to drive, three tests of balance and coordination were evaluated and vital signs (blood pressure and pulse) were measured. Dried blood spot samples of capillary blood were taken after smoking and after completion of the tests to determine the cannabinoid concentrations (CBD, THC and THC-metabolites). The results revealed no significant differences between the effects of smoking CBD-rich marijuana and placebo on reaction time, motor time, behaviour under stress, or concentration performance. Maximum free CBD and THC concentrations in capillary blood were detected shortly after smoking, ranging between 2.6-440.0 ng/mL and 6.7-102.0 ng/mL, respectively. After 45 min, capillary blood concentrations had already declined and were in the range of 1.9-135.0 ng/mL (free CBD) and 0.9-38.0 ng/mL (free THC). Although the observed levels of free THC concentrations have been reported to cause symptoms of impairment in previous studies in which THC-rich marijuana was smoked, no signs of impairment were found in the current study. This finding suggests that higher CBD concentrations cause a negative allosteric effect in the endocannabinoid system, preventing the formation of such symptoms. Nevertheless, it is recommended that consumers refrain from driving for several hours after smoking CBD-rich marijuana, as legal THC concentration limits may be exceeded. Supplemental data for this article is available online at https://doi.org/10.1080/20961790.2021.1946924 .

Dried blood sample analysis by antibody array across the total testing process

Dried blood samples (DBSs) have many advantages; yet, impediments have limited the clinical utilization of DBSs. We developed a novel volumetric sampling device that collects a precise volume of blood, which overcomes the heterogeneity and hematocrit issues commonly encountered in a traditional DBS card collection as well as allowing for more efficient extraction and processing procedures and thus, more efficient quantitation, by using the entire sample. We also provided a thorough procedure validation using this volumetric DBS collection device with an established quantitative proteomics analysis method, and then analyzed 1000 proteins using this approach in DBSs concomitantly with serum for future consideration of utility in clinical applications. Our data provide a first step in the establishment of a DBS database for the broad application of this sample type for widespread use in clinical proteomic and other analyses applications.

Genetic identification of the causative agent of Brucellosis

The development of animal husbandry suffers various kinds of losses due to the spread of infectious diseases among animals, in particular Brucellosis. A challenge faced by Brucella researchers has been the accurate identification of new isolates within the genus while preserving sufficient, and not excessive, biosafety and biosecurity requirements. The availability of discriminatory molecular typing tools to inform and assist conventional epidemiological approaches would be invaluable in controlling these infections, but efforts have been hampered by the genetic homogeneity of the genus. In this work, for better identification of infection, for control and monitor the source of outbreaks in prosperous areas was carried out identification of Brucella spp. strains which circulating in the Kostanay region. For this was used using multilocus analysis of a variable number of tandem repeats sequenced by 16 s – PNK on a genetic analyzer (sequencer). According to the results of a study of cattle, cultures of microorganisms were infected: No. 4, 5, 7, 8. Comparison of the obtained results with similar results of domestic and foreign works by A. Shevtsov, G. Borrello, P. Le Fleche, G. Garofolo suggest that the genotyping of local strains has an importance in the molecular epizootology of the Republic of Kazakhstan.

Simultaneous quantification of vincristine and its major M1 metabolite from dried blood spot samples of Kenyan pediatric cancer patients by UPLC-MS/MS

Vincristine (VCR) is an integral part of chemotherapy regimens in the US and in developing countries. There is a paucity of information about its disposition and optimal therapeutic dosing. VCR is preferentially metabolized to its major M1 metabolite by the polymorphic CYP3A5 enzyme, which may be clinically significant as CYP3A5 expression varies across populations. Thus, it is important to monitor both VCR and M1 and characterize their dispositions. A previously developed HPLC-MS/MS method for VCR quantification was not sensitive enough to quantify the M1 metabolite beyond 1 h post VCR dose (not published). Establishing a highly sensitive assay is a pre-requisite to simultaneously quantify and monitor VCR and M1, which will enable characterization of drug exposure and dispositions of both analytes in a pediatric cancer population. The addition of formic acid during the extraction process enhanced M1 extraction from DBS samples. A sensitive, accurate, and precise UPLC-MS/MS assay method for the simultaneous quantification of VCR and M1 from human dried blood spots (DBS) was developed and validated. Chromatographic separation was performed on Inertsil ODS-3 C18 column (5 μm, 3.0 × 150 mm). A gradient elution of mobile phase A (methanol-0.2 % formic acid in water, 20:80 v/v) and mobile phase B (methanol-0.2 % formic acid in water, 80:20 v/v) was used with a flow rate of 0.4 mL/min and a total run time of 5 min. The analytes were ionized by electrospray ionization in the positive ion mode. The linearity range for both analytes in DBS were 0.6-100 ng/mL for VCR and 0.4-100 ng/mL for M1. The intra- and inter-day accuracies for VCR and M1 were 93.10-117.17 % and 95.88-111.21 %, respectively. While their intra- and inter-day precisions were 1.05-10.11 % and 5.78-8.91 %, respectively. The extraction recovery of VCR from DBS paper was 35.3-39.4 % and 10.4-13.4 % for M1, with no carryover observed for both analytes. This is the first analytical method to report the simultaneous quantification of VCR and M1 from human DBS. For the first time, concentrations of M1 from DBS patient samples were obtained beyond 1 h post VCR dose. The developed method was successfully employed to monitor both compounds and perform pharmacokinetic analysis in a population of Kenyan pediatric cancer patients.

Untargeted Lipidomic Profiling of Dry Blood Spots Using SFC-HRMS

Lipids are essential cellular constituents that have many critical roles in physiological functions. They are notably involved in energy storage and cell signaling as second messengers, and they are major constituents of cell membranes, including lipid rafts. As a consequence, they are implicated in a large number of heterogeneous diseases, such as cancer, diabetes, neurological disorders, and inherited metabolic diseases. Due to the high structural diversity and complexity of lipid species, the presence of isomeric and isobaric lipid species, and their occurrence at a large concentration scale, a complete lipidomic profiling of biological matrices remains challenging, especially in clinical contexts. Using supercritical fluid chromatography coupled with high-resolution mass spectrometry, we have developed and validated an untargeted lipidomic approach to the profiling of plasma and blood. Moreover, we have tested the technique using the Dry Blood Spot (DBS) method and found that it allows for the easy collection of blood for analysis. To develop the method, we performed the optimization of the separation and detection of lipid species on pure standards, reference human plasma (SRM1950), whole blood, and DBS. These analyses allowed an in-house lipid data bank to be built. Using the MS-Dial software, we developed an automatic process for the relative quantification of around 500 lipids species belonging to the 6 main classes of lipids (including phospholipids, sphingolipids, free fatty acids, sterols, and fatty acyl-carnitines). Then, we compared the method using the published data for SRM 1950 and a mouse blood sample, along with another sample of the same blood collected using the DBS method. In this study, we provided a method for blood lipidomic profiling that can be used for the easy sampling of dry blood spots.

Trace elements in dried blood spots as potential discriminating features for metabolic disorder diagnosis in newborns

Trace elements in dried blood spots (DBSs) from newborns were determined by laser ablation coupled with inductively coupled plasma mass spectrometry, and data were subjected to chemometric evaluation in an attempt to classify healthy newborns and newborns suffering from metabolic disorders. Unsupervised [principal component analysis (PCA) and cluster analysis (CA)] and supervised [linear discriminant analysis (LDA) and soft independent modeling by class analogy (SIMCA)] pattern recognition techniques were used as classification techniques. PCA and CA have shown a clear tendency to form two groups (healthy newborns and newborns suffering from metabolic disorders). LDA and SIMCA have predicted that 90.5% and 83.9% of originally grouped healthy newborn cases were correctly classified by LDA and SIMCA, respectively. In addition, these percentages were 97.6% (LDA) and 80.6% (SIMCA) for DBSs from newborns suffering from metabolic disorders. However, SIMCA has only detected one misclassified DBS from the healthy group, and the lower percentage is attributed to four DBSs from the healthy newborn group and five DBSs from newborns with disorders that were found as belonging to both categories (healthy newborns and newborns with disorders) in the training set. LDA also gave a percentage of grouped maple syrup urine disease (MSUD) cases correctly classified of 100%, although the percentage fells to 66.7% when classifying phenylketonuria (PKU) cases. Finally, essential elements such as Fe, K, Rb, and Zn were found to be matched (correlated) with the concentration of amino acids such as phenylalanine, valine, and leucine, biomarkers linked with MSUD and PKU diseases.

Development and validation of an LC-MS/MS method for relevant drugs in epilepsy patients using dried blood spots

Epilepsy is one of the most common diseases of the central nervous system globally. To ensure the correct dosage of antiepileptic treatment, it is helpful to check the blood levels of the administered substances regularly. The analysis of the capillary dried blood samples provides a promising and less-invasive alternative to venous blood collection. Therefore, the aim of the present study was to develop an LC-MS method for the quantification of 22 commonly used drugs in patients with an epileptic syndrome and 5 drug metabolites in one dried blood spot (DBS). The calibration ranges were selected in such a way that the therapeutic reference ranges in serum for the respective substances were completely covered. The analytical validation was successfully performed according to relevant guidelines with a consideration of requirements for DBS analysis. Proof of concept of the developed method was obtained by the analysis of DBSs from 282 authentic leftover ethylenediaminetetraacetic acid blood samples, which were compared with the corresponding serum concentrations. Altogether, the results show a dependency on the blood/plasma (b/p) ratios of the respective analytes so that for drugs with b/p ratios close to one, for example, lacosamide, levetiracetam, brivaracetam, and sertraline, a good accordance was observed.

A convenient sampling and noninvasive dried spot method of uric acid in human saliva: Comparison of serum uric acid value and salivary uric acid in healthy volunteers and hyperuricemia patients

Concentration of uric acid (UA) in serum is one of the markers used to diagnose gout and hyperuricemia. However, serum treatment and storage are cumbersome, and wounds are susceptible to infection. Therefore, a new sampling and analysis method using noninvasive biological samples has been developed, called the dried spot method of UA in human saliva (DSM-UHS). Saliva (5 μL) was dropped on filter paper (a spot with a diameter of 5 mm) containing hypoxanthine (IS) (5 μL) and dried at room temperature for 30 min. The filter paper was immersed in 200 μL of lithium carbonate solution and shaken in a block bath shaker for 5 min at 30 °C. Afterward, the extraction was concentrated and reconstituted with 100 μL of lithium carbonate solution analyzed by HPLC-UV. When comparing the concentration of UA in the human saliva of hyperuricemia patients (HPs) and with that of healthy volunteers (HVs), we observed the concentration of UA was higher in the HPs than in the HVs (p < 0.0001). In addition, the results showed a significant linear relationship between the content of UA in saliva and the content of UA in the serum (r = 0.6243). The content of UA in human saliva could indirectly reflect the content of UA in human serum. Then DSM-UHS could be used to determine the content of UA in the saliva of HVs and HPs. This study provides a new research method and strategy for the determination of human UA content and the clinical prewiring of hyperuricemia.

A comparison between two different dried blood substrates in determination of psychoactive substances in postmortem samples

Purpose

Whatman™ 903 cards represent a valid type of support for collection, storage, and analysis of dried blood spots (DBS). Whatman™ FTA (Flinders Technology Associates) are a type of cards soaked in chemicals that cause denaturation of proteins, while preserving DNA and ensuring the safe handling of DBS; to date, these cards are still rarely employed in forensic toxicology. The aim of this study was to analyze several psychoactive substances on not-dried blood on the two different cards and to compare the qualitative and quantitative results.

Methods

Twenty cardiac postmortem blood samples were collected and deposed on Whatman™ 903 and Whatman™ FTA cards. Spots and not-dried blood were analyzed following our validated and previously published liquid chromatography-mass spectrometry methods.

Results

We were able to identify: eight drugs of abuse and their metabolites (15 cases), five benzodiazepines and their metabolites (3 cases), six antidepressants (6 cases) and two antipsychotics (3 cases). We observed a perfect qualitative correspondence and a general good quantitative correlation between data obtained from not-dried blood and the two different DBS cards, except for alprazolam, diazepam, desmethyldiazepam, fluoxetine and sertraline, that showed a lower concentration on FTA. Additional experiments suggest that the chemicals, adsorbed on FTA, are not the cause of the loss of signal observed for the substances previously mentioned and that methanol should be preferred as extraction solvent.

Conclusions

This study proved that FTA cards are a good and a hazard-free alternative sample storage method for analysis of several psychoactive substances in postmortem blood.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11419-020-00567-2.

Dried Blood-Based Protein Profiling Using Antibody Arrays

Dried blood samples have been increasingly considered for clinical applications in recent years. The main disadvantages that limit DBS utility in clinical applications are the small sample volume collected, area bias and homogeneity issues, and sample preparation requirements for the necessary sensitivity and reproducibility required for clinical assessment. The recent advances in antibody array technology overcome the common disadvantages of immunoassay approaches by increasing the multiplex capabilities and decreasing the sample volume requirements as well as minimizing the expense and technical expertise required with many alternative high-density approaches like mass spectrometry.

A New Paper-Based Microfluidic Device for Improved Detection of Nitrate in Water

In this paper, we report a simple and inexpensive paper-based microfluidic device for detecting nitrate in water. This device incorporates two recent developments in paper-based technology suitable for nitrate detection and has an optimized microfluidic design. The first technical advancement employed is an innovative fibrous composite material made up of cotton fibers and zinc microparticles that can be incorporated in paper-based devices and results in better nitrate reduction. The second is a detection zone with an immobilized reagent that allows the passage of a larger sample volume. Different acids were tested—citric and phosphoric acids gave better results than hydrochloric acid since this acid evaporates completely without leaving any residue behind on paper. Different microfluidic designs that utilize various fluid control technologies were investigated and a design with a folding detection zone was chosen and optimized to improve the uniformity of the signal produced. The optimized design allowed the device to achieve a limit of detection and quantification of 0.53 ppm and 1.18 ppm, respectively, for nitrate in water. This accounted for more than a 40% improvement on what has been previously realized for the detection of nitrate in water using paper-based technology.

N-glycosylation analysis of mouse immunoglobulin G isolated from dried blood spots

The association of immunoglobulin G (IgG) glycosylation changes with various human diseases and physiological conditions is well established. Since the mechanistical explanation of the regulation of IgG glycosylation and its functional role in these various states is still missing, the eyes of the biomedical community are now turned towards animal models, which enable intervention studies necessary for conclusions on causality. Mice are recognized and used as a good experimental model for human IgG glycosylation. However, smaller blood volumes, low IgG concentrations at young ages (which are most often used in mice experiments) and multiple sampling protocols during the course of longitudinal studies would profit from a robust workflow for mouse IgG glycome analysis from minute amounts of starting material, collected through a simple sampling procedure. For this purpose, we have developed a protocol for analysis of total N-glycans of IgG isolated from mouse dried blood spots (DBS), which we report here. We show that mouse DBS are a good source of material for IgG N-glycan analysis by multiplexed capillary gel electrophoresis with laser-induced fluorescence (xCGE-LIF).

Diagnostic prediction model development using data from dried blood spot proteomics and a digital mental health assessment to identify major depressive disorder among individuals presenting with low mood

With less than half of patients with major depressive disorder (MDD) correctly diagnosed within the primary care setting, there is a clinical need to develop an objective and readily accessible test to enable earlier and more accurate diagnosis. The aim of this study was to develop diagnostic prediction models to identify MDD patients among individuals presenting with subclinical low mood, based on data from dried blood spot (DBS) proteomics (194 peptides representing 115 proteins) and a novel digital mental health assessment (102 sociodemographic, clinical and personality characteristics). To this end, we investigated 130 low mood controls, 53 currently depressed individuals with an existing MDD diagnosis (established current MDD), 40 currently depressed individuals with a new MDD diagnosis (new current MDD), and 72 currently not depressed individuals with an existing MDD diagnosis (established non-current MDD). A repeated nested cross-validation approach was used to evaluate variation in model selection and ensure model reproducibility. Prediction models that were trained to differentiate between established current MDD patients and low mood controls (AUC = 0.94 ± 0.01) demonstrated a good predictive performance when extrapolated to differentiate between new current MDD patients and low mood controls (AUC = 0.80 ± 0.01), as well as between established non-current MDD patients and low mood controls (AUC = 0.79 ± 0.01). Importantly, we identified DBS proteins A1AG1, A2GL, AL1A1, APOE and CFAH as important predictors of MDD, indicative of immune system dysregulation; as well as poor self-rated mental health, BMI, reduced daily experiences of positive emotions, and tender-mindedness. Despite the need for further validation, our preliminary findings demonstrate the potential of such prediction models to be used as a diagnostic aid for detecting MDD in clinical practice.

Analytical Chemistry in the 21st Century: Challenges, Solutions, and Future Perspectives of Complex Matrices Quantitative Analyses in Biological/Clinical Field

Nowadays, the challenges in analytical chemistry, and mostly in quantitative analysis, include the development and validation of new materials, strategies and procedures to meet the growing need for rapid, sensitive, selective and green methods. In this context, considering the constantly updated International Guidelines, constant innovation is mandatory both in the pre-treatment procedures and in the instrumental configurations to obtain reliable, true, and reproducible information. In this context, additionally to the classic plasma (or serum) matrices, biopsies, whole blood, and urine have seen an increase in the works that also consider non-conventional matrices. Obviously, all these studies have shown that there is a correlation between the blood levels and those found in the new matrix, in order to be able to correlate and compare the results in a robust way and reduce any bias problems. This review provides an update of the most recent developments currently in use in the sample pre-treatment and instrument configurations in the biological/clinical fields. Furthermore, the review concludes with a series of considerations regarding the role and future developments of Analytical Chemistry in light of the forthcoming challenges and new goals to be achieved.

Capillary Zone Electrophoresis-Top-Down Tandem Mass Spectrometry for In-Depth Characterization of Hemoglobin Proteoforms in Clinical and Veterinary Samples

Hemoglobin (Hb) constitutes an important protein in clinical diagnostics-both in humans and animals. Among the high number of sequence variants, some can cause severe diseases. Moreover, chemical modifications such as glycation and carbamylation serve as important biomarkers for conditions such as diabetes and kidney diseases. In clinical routine analysis of glycated Hb, sequence variants or other Hb proteoforms can cause interference, resulting in wrong quantification results. We present a versatile and flexible capillary zone electrophoresis-mass spectrometry screening method for Hb proteoforms including sequence variants and modified species extracted from dried blood spot (DBS) samples with virtually no sample preparation. High separation power was achieved by application of a 5-layers successive multiple ionic polymer layers-coated capillary, enabling separation of positional isomers of glycated α- and β-chains on the intact level. Quantification of glycated Hb was in good correlation with the results obtained in a clinical routine method. Identification and characterization of known and unknown proteoforms was performed by fragmentation of intact precursor ions. N-Terminal and lysine glycation could be identified on the α- and β-chain, respectively. The versatility of the method was demonstrated by application to dog and cat DBS samples. We discovered a putative new sequence variant of the β-chain in dog (T38 → A). The presented method enables separation, characterization, and quantification of intact proteoforms, including positional isomers of glycated species in a single run. Combined with the simple sample preparation, our method represents a valuable tool to be used for deeper characterization of clinical and veterinary samples.

Dried Blood Spot in Laboratory: Directions and Prospects

Over the past few years, dried blood spot (DBS) technology has become a convenient tool in both qualitative and quantitative biological analysis. DBS technology consists of a membrane carrier (MC) on the surface of which a biomaterial sample becomes absorbed. Modern analytical, immunological or genomic methods can be employed for analysis after drying the sample. DBS has been described as the most appropriate method for biomaterial sampling due to specific associated inherent advantages, including the small volumes of biomaterials required, the absence of a need for special conditions for samples’ storage and transportation, improved stability of analytes and reduced risk of infection resulting from contaminated samples. This review illustrates information on the current state of DBS technology, which can be useful and helpful for biomedical researchers. The prospects of using this technology to assess the metabolomic profile, assessment, diagnosis of communicable diseases are demonstrated.

Comprehensive N-glycosylation analysis of immunoglobulin G from dried blood spots

Immunoglobulin G (IgG) glycans are emerging as a new putative biomarker for biological age and different diseases, requiring a robust workflow for IgG glycome analysis, ideally beginning with a simple and undemanding sampling procedure. Here, we report the first comprehensive study on total N-glycans of IgG isolated from dried blood spots (DBSs), which was performed in a high-throughput mode. We compared the IgG N-glycan profiles originating from DBS with those originating from plasma, compared different media for DBS collection, evaluated analytical variation and assessed IgG N-glycan profile stability for different storage conditions. In conclusion, we show that DBSs are a good and stable source material for a robust IgG N-glycan analysis by ultra-performance liquid chromatography, suitable for blood sampling in conditions where no trained personnel and necessary laboratory equipment are available.