Potential use of a dried saliva spot (DSS) in therapeutic drug monitoring and disease diagnosis

Standardization of Microsampling Technologies for Accurate Sensing and Reliable Diagnostics

The COVID-19 pandemic demonstrated the debilitating effect of overreliance on centralized sampling and testing, and generated significant momentum to investigate and validate sample types that are alternatives to the gold standard (e.g., anterior nasal vs nasopharyngeal swabs). As a result, sample collection is trending away from traditional methods at centralized health care facilities and toward at-home or point-of-care settings with devices that enable self-collection. With shifts away from regulated environments and trained personnel, it is important to remember that reliable measurements begin with standardized sample collection. To develop microsampling technologies for applications where the outcome can impact health care decisions, it is critical to (i) fully understand the sample collected (e.g., volume, composition, biological factors) and (ii) implement engineering controls for users and clinical workflow integration (e.g., usability, volume metering) to ensure precision and accuracy of a measurement. Blood sampling, once exclusively performed via venipuncture, has made the greatest strides toward remote collection with the introduction of lancet- and microneedle-based, capillary microsampling devices. However, challenges remain toward standardizing these methods, such as ensuring that measurements are hematocrit-independent. Other sample types (e.g., nasal fluid, saliva) face similar hurdles. In this Perspective, we review the current state of self-collection microsampling technologies and highlight the need to develop tools that can (i) standardize sample collection and (ii) seamlessly integrate with current clinical workflows. Ultimately, we advocate for continued innovation as technologies that support self-collection have the potential to greatly improve the diagnostic process for patients, reduce the burden on health care workers, and advance the shift toward decentralized testing.

Liquid saliva analysis using optofluidic photonic crystal fiber for detection of oral potentially malignant disorders

Oral potentially malignant disorders (OPMD) serve as early indicators of oral cancer. These conditions require reliable, non-invasive and real-time diagnostic methods for effective detection and screening. Saliva, as an easily accessible and non-invasive biofluid, has emerged as a promising tool to detect OPMD-associated biomarkers. This proof-of-concept study investigated the application of suspended-core optofluidic photonic crystal fibers (PCF) for Raman spectroscopy to distinguish between saliva from healthy controls and OPMD patients. This novel approach provides enhanced Raman signals through prolonged interactions between the excitation light and the saliva sample along the length of the PCF. Raman spectra of liquid saliva samples were collected from eleven participants, including six OPMD patients and five healthy controls. Notable spectral differences were identified at 1123 cm-1, 1251 cm-1, and 1454 cm-1, which correspond to carbohydrates, proteins, and lipids, respectively. In vivo tissue measurements were recorded as a reference for comparative analysis from the same patients. Our findings suggest that PCF-based Raman spectroscopy holds promise as a non-invasive diagnostic platform for oral cancer screening by enabling the monitoring of subtle molecular changes in liquid saliva.

Determination of drugs of abuse in oral fluid using dried oral fluid spot assisted by 24-well plate and LC-MS/MS

BACKGROUND

Oral fluid has proven to be an excellent matrix for drug testing. Several analytical techniques are available, including the use of dried spots, which have gained increasing recognition in recent years. In this study, a new method was developed and validated using dried oral fluid spot (DOFS) assisted by a 24-well plate for the simultaneous determination of thirteen drugs of abuse and metabolites in oral fluid by LC - MS/MS.

METHODS

Samples were collected by expectoration and diluted with water. A 100 μL aliquot of sample was applied onto the spot, dried for 60 min, and extracted with 250 μL of acetonitrile:methanol (3:1). The method was validated according to the ANSI/ASB Standard 036 guideline, and 86 oral fluid samples were analyzed.

RESULTS

The limits of quantification ranged from 1 to 5 ng/mL, and all calibration curves were linear. Precisions ranged from 2.0 to 13.0% and Bias fluctuated from -19.7 to 9.6%. Ionization suppression or enhancement was noted at -16.2 to 16.6%. Among the analyzed samples, 86% tested positive for at least one substance.

CONCLUSIONS

The findings confirm that the proposed method was successfully validated, providing a new bioanalytical approach for the detection of drugs of abuse in oral fluid.

Properties and antibacterial effectiveness of metal-ion doped borate-based bioactive glasses

Bioactive glasses (BGs) are physiologically reactive surface biomaterials widely used in biomedical applications and various treatments. Borate bioactive glasses (BBGs) are third-generation BGs, and they exhibit superior biodegradable, bioactive, osteoconductive, antibacterial, and biocompatible properties compared to other types of BGs. Certain concentrations of dopant ions can be incorporated into the chemical structure of BBGs to enhance their biological functionalities and antimicrobial properties. It was demonstrated that those ions play a crucial role in the biological responsiveness in vitro and in vivo once in contact with a physiological environment. The dissolution products of ion-doped BBGs were noted in their ability to stimulate gene expression related to cell differentiation and proliferation, promote angiogenesis, display anti-inflammatory effects, and inhibit bacterial growth within a few hours. Thus, metal-ion-doped BBGs address several limitations encountered by biomedical, tissue engineering, and infection control applications. Considering the research studies on BBGs to date, this review aims to analyze metal-ion-doped BBGs based on their primary antibacterial properties and effectiveness.

Monitoring SARS-CoV-2 IgA, IgM and IgG antibodies in dried blood and saliva samples using antibody proximity extension assays (AbPEA)

Using a modified proximity extension assay, total and immunoglobulin (Ig) class-specific anti-SARS-CoV-2 antibodies were sensitively and conveniently detected directly from ø1.2 mm discs cut from dried blood and saliva spots (DBS and DSS) without the need for elution. For total Ig detection, antigen probes were prepared by conjugating recombinant spike protein subunit 1 (S1-RBD) to a pair of oligonucleotides. To detect isotype-specific antibody reactivity, one antigen probe was replaced with oligonucleotide-conjugated antibodies specific for antibody isotypes. Binding of pairs of oligonucleotide-conjugated probes to antibodies in patient samples brings oligonucleotides in proximity. An added DNA polymerase uses a transient hybridization between the oligonucleotides to prime synthesis of a DNA strand, which serves as a DNA amplicon that is quantified by real-time PCR. The S1-RBD-specific IgG, IgM, and IgA antibodies in DBS samples collected over the course of a first and second vaccination exhibited kinetics consistent with previous reports. Both DBS and DSS collected from 42 individuals in the autumn of 2023 showed significant level of total S1-RBD antibodies with a correlation of R = 0.70. However, levels in DSS were generally 10 to 100-fold lower than in DBS. Anti-S1-RBD IgG and IgA in DSS demonstrated a correlation of R = 0.6.

A dried sweat spot paper (DSSP) method based on novel mass spectrometry probe labeling for detection and resolution of DL-lactate enantiomers as potential biomarkers for diabetes mellitus

BACKGROUND

Human sweat can be collected non-invasively with low infectivity; however, its application as a determination method has been challenged due to the presence of trace amounts of chiral metabolites. Moreover, its application as a biological fluid for disease diagnosis has not been previously reported. In this study, the human dried sweat spot paper (DSSP) method was proposed for the derivatization of a novel mass spectrometric chiral probe, N-[1-Oxo-5-(triphenylphosphonium) pentyl]-(S)-3-aminopyrrolidine (OTPA), determination and resolution of DL-lactic acid (DL-LA) enantiomers in human elbow sweat.

RESULTS

The methodological validation revealed the resolution (Rs) as 1.78, the limit of detection (S/N = 3) as 20.83 fmol, good linearity (R2 ≥ 0.9996), and the intra-day and intra-day stability with RSD ranging from 0.53 to 10.85 %, while the average recovery rate of D-LA and L-LA were 104.00 % ± 4.68 % and 107.41 % ± 8.34 %, respectively, with high accuracy. In addition, the method was applied for the determination of DL-LA in the sweat on elbow of 10 healthy volunteers and 30 diabetic patients. The results demonstrated that the D/L ratio and L/D ratio were significantly different (p < 0.0001). In addition, a moderate positive linear correlation between the D/L-LA ratio in human sweat and fasting blood glucose level (r = 0.7744, p < 0.0001) was observed, thereby suggesting that the D/L ratio of lactate in human sweat correlate the glucose level in human fasting blood.

SIGNIFICANCE AND NOVELTY

The D/L lactate ratio in human sweat could be used as a potential biomarker for diabetes screening. The method can be used to screen for diabetes by providing a dry sweat paper to test equipment and has the potential to be a non-invasive early-warning diagnostic tool for diabetes.

Biological Fluid Microsampling for Therapeutic Drug Monitoring: A Narrative Review

Therapeutic drug monitoring (TDM) is a specialized area of laboratory medicine which involves the measurement of drug concentrations in biological fluids with the aim of optimizing efficacy and reducing side effects, possibly modifying the drug dose to keep the plasma concentration within the therapeutic range. Plasma and/or whole blood, usually obtained by venipuncture, are the "gold standard" matrices for TDM. Microsampling, commonly used for newborn screening, could also be a convenient alternative to traditional sampling techniques for pharmacokinetics (PK) studies and TDM, helping to overcome practical problems and offering less invasive options to patients. Although technical limitations have hampered the use of microsampling in these fields, innovative techniques such as 3-D dried blood spheroids, volumetric absorptive microsampling (VAMS), dried plasma spots (DPS), and various microfluidic devices (MDS) can now offer reliable alternatives to traditional samples. The application of microsampling in routine clinical pharmacology is also hampered by the need for instrumentation capable of quantifying analytes in small volumes with sufficient sensitivity. The combination of microsampling with high-sensitivity analytical techniques, such as liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS), is particularly effective in ensuring high accuracy and sensitivity from very small sample volumes. This manuscript provides a critical review of the currently available microsampling devices for both whole blood and other biological fluids, such as plasma, urine, breast milk, and saliva. The purpose is to provide useful information in the scientific community to laboratory personnel, clinicians, and researchers interested in implementing the use of microsampling in their routine clinical practice.

Advances and perspectives in the analytical technology for small peptide hormones analysis: A glimpse to gonadorelin

In the last twenty years, we have witnessed an important evolution of bioanalytical approaches moving from conventional lab bench instrumentation to simpler, easy-to-use techniques to deliver analytical responses on-site, with reduced analysis times and costs. In this frame, affinity reagents production has also jointly advanced from natural receptors to biomimetic, abiotic receptors, animal-free produced. Among biomimetic ones, aptamers, and molecular imprinted polymers (MIPs) play a leading role. Herein, our motivation is to provide insights into the evolution of conventional and innovative analytical approaches based on chromatography, immunochemistry, and affinity sensing referred to as peptide hormones. Indeed, the analysis of peptide hormones represents a current challenge for biomedical, pharmaceutical, and anti-doping analysis. Specifically, as a paradigmatic example, we report the case of gonadorelin, a neuropeptide that in recent years has drawn a lot of attention as a therapeutic drug misused in doping practices during sports competitions.

Evaluation of Antipsychotic Drugs' Stability in Oral Fluid Samples

Antipsychotics have narrow therapeutic windows, and their monitoring in biological fluids is therefore important; consequently, stability in those fluids must be investigated during method development and validation. This work evaluates the stability of chlorpromazine, levomepromazine, cyamemazine, clozapine, haloperidol, and quetiapine in oral fluid (OF) samples, using the dried saliva spots (DSS) sampling approach and gas chromatography coupled to tandem mass spectrometry. Since many parameters can influence the stability of the target analytes, design of experiments was adopted to check the crucial factors that affect that stability in a multivariate fashion. The studied parameters were the presence of preservatives at different concentrations, temperature, light, and time. It was possible to observe that antipsychotic stability improved when OF samples in DSS were stored at 4 °C, with a low ascorbic acid concentration, and in the absence of light. With these conditions, chlorpromazine and quetiapine were stable for 14 days, clozapine and haloperidol were stable for 28 days, levomepromazine remained stable for 44 days, and cyamemazine was stable for the entire monitored period (146 days). This is the first study that evaluates the stability of these antipsychotics in OF samples after application to DSS cards.

Saliva Sampling in Therapeutic Drug Monitoring and Physiologically Based Pharmacokinetic Modeling: Review

Therapeutic drug monitoring investigations based on saliva samples can be utilized as an alternative to blood sampling for many advantages. Moreover, the development of physiologically based pharmacokinetic (PBPK) modeling tools can further help to estimate drug exposure from saliva. This review discusses the use of saliva samples and illustrates the applications and examples of PBPK modeling systems for estimating drug exposure from saliva.

Rapid Detection of Amitriptyline in Dried Blood and Dried Saliva Samples with Surface-Enhanced Raman Spectroscopy

There is growing demand for rapid, nondestructive detection of trace-level bioactive molecules including medicines, toxins, biomolecules, and single cells, in a variety of disciplines. In recent years, surface-enhanced Raman scattering has been increasingly applied for such purposes, and this area of research is rapidly growing. Of particular interest is the detection of such compounds in dried saliva spots (DSS) and dried blood spots (DBS), often in medical scenarios, such as therapeutic drug monitoring (TDM) and disease diagnosis. Such samples are usually analyzed using hyphenated chromatography techniques, which are costly and time consuming. Here we present for the first time a surface-enhanced Raman spectroscopy protocol for the detection of the common antidepressant amitriptyline (AMT) on DBS and DSS using a test substrate modified with silver nanoparticles. The validated protocol is rapid and non-destructive, with a detection limit of 95 ppb, and linear range between 100 ppb and 1.75 ppm on the SERS substrate, which covers the therapeutic window of AMT in biological fluids.