D-amino acids (D-AAs) are important signaling molecules due to their ability to bind ionotropic N-methyl-D-aspartate receptors. D-serine (D-Ser), D-alanine (D-Ala), and D-aspartate (D-Asp) have been found individually in the endocrine portion of the pancreas, the islets of Langerhans, and/or their secretions. However, there has been no report of a comprehensive assessment of D-AAs in islet secretions. To evaluate the release of these compounds, the effectiveness of both 1-(9-fluorenyl)-ethyl chloroformate (FLEC reagent) and 1-fluoro-2,4-dinitrophenyl-5-L-alanine amide (Marfey's reagent, MR) in separation of D/L-AA enantiomeric pairs in islet-specific buffers were evaluated. MR-derivatized D/L AAs showed greater than baseline resolution (Rs ≥ 1.5) of 13 enantiomeric pairs when using a non-linear gradient and an acidic mobile phase system, while FLEC-derivatized AAs exhibited limited resolution on both biphenyl and C18 columns. The optimized MR method yielded highly reproducible separations with retention times less than 1% RSD. Excellent linearity between the analyte concentrations and response (R > 0.98) were obtained, with less than 15% RSD for all analyte responses. Most analytes had an LOD at or below 100 nM, except for L-Ala (200 nM). The optimized MR method was used to quantify D-AAs in secretions of 150 murine islets after incubation in 3- and 20-mM glucose. In response to both solutions, D-Ser and D-glutamine were tentatively identified via comparison of retention time and quantifier-to-qualifer ion ratios with standards, and from spiking experiments. Both were secreted in low quantities which did not differ significantly in either low (D-Ser: 44 ± 2 fmol isleth; D-Gln: 300 ± 100 fmol isleth) or high (D-Ser: 23 ± 1 fmol isleth; D-Gln: 120 ± 50 fmol isleth) glucose across 3 biological replicates. The method developed is robust and can be applied to further examine the release of D-AAs and their potential roles in islet physiology.
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http://dx.doi.org/10.1016/j.jchromb.2023.123928 | DOI Listing |
Bioelectrochemistry
January 2025
The Key Laboratory of Biomedical Material, School of Life Science and Technology, Xinxiang Medical University, Xinxiang 453003 China. Electronic address:
To provide accurate diagnostic evidence for early hepatitis B virus (HBV) infection-related diseases, this study targeted HBV DNA as an analyte, where a sandwich-type electrochemical DNA sensor based on gold nanoparticles/reduced graphene oxide (Au NPs/ERGO) and cerium oxide/gold-platinum nanoparticles (CeO/AuPt NPs) was constructed. Au NPs/ERGO composite nanomaterials were first synthesized on the surface of a glass carbon electrode using electrochemical co-reduction, which significantly improved the specific surface area and electrical conductivity of the electrode. Further specific hybridization of target HBV-DNA was performed by combining capture probe DNA (S1-DNA) bound to AuNPs/ERGO with CeO/AuPt modified signal probe DNA (S2-DNA).
View Article and Find Full Text PDFAnal Chem
January 2025
Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita 565-0871, Japan.
Prior to mass spectrometry (MS) analysis, pretreatment of low-abundance glycopeptides is vital for identifying protein glycosylation. In this study, we fabricated an environmentally friendly citric-acid-modified cellulose monolith (CCM) characterized by a coral-like porous structure and high-density hydrophilic groups using a thermally induced phase separation (TIPS) method. The CCM production leverages biomass resources, specifically cellulose and citric acid, utilizing TIPS to synthesize continuous porous materials through a straightforward heating and cooling process of polymer solutions.
View Article and Find Full Text PDFBioorg Med Chem
December 2024
Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, United States. Electronic address:
The purinergic P2X ligand-gated ion channel 7 receptor (P2X7R) plays a critical role in various inflammatory processes and other diseases. Fast determination of compounds P2X7R binding potency and discovery of a promise PET radiotracer for imaging P2X7R require a P2X7R suitable radioligand for radioactive competitive binding assay. Herein, we designed and synthesized thirteen new P2X7R ligands and determined the in vitro binding potency.
View Article and Find Full Text PDFPLoS One
December 2024
Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, Bahia, Brazil.
Background: Consistent monitoring of PrEP adherence with accurate measurement tools at point-of-care could greatly contribute to reaching adolescents with poor adherence. We aimed to assess the performance of indirect adherence measures to oral PrEP among adolescent men who have sex with men (AMSM) and adolescent transgender women (ATGW).
Methods: PrEP15-19 is a prospective, multicenter, PrEP demonstration cohort study that includes AMSM and ATGW aged 15-19 in three Brazilian cities.
Talanta
December 2024
Electroanalytical Chemistry Laboratory, Faculty of Chemistry, University of Guilan, Namjoo Street, P.O. Box: 1914-41335, Rasht, Iran.
Glutathione (GSH) is a bioactive tripeptide with important physiological functions in animals, plants, and microorganisms. GSH participates in various biochemical reactions in vivo and is known for its antioxidant, anti-allergy, and detoxification properties. This study introduces an innovative photoelectrochemical (PEC) method for GSH detection, leveraging a fluorine-doped tin oxide (FTO) electrode enhanced by TiO nanoflowers and graphitic carbon nitride quantum dots (g-CNQDs).
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