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Lenhart AE, Booth PPM, Simcox KM, Ramos BA, Kennedy RT. Systematic evaluation of benzoylation for liquid chromatography-mass spectrometry analysis of different analyte classes. J Chromatogr A 2024; 1722:464872. [PMID: 38581975 DOI: 10.1016/j.chroma.2024.464872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Revised: 04/01/2024] [Accepted: 04/03/2024] [Indexed: 04/08/2024]
Abstract
LC-MS is an indispensable tool for small molecule analysis in many fields; however, many small molecules require chemical derivatization to improve retention on commonly used reversed-phase columns and increase ionization. Benzoyl chloride (BzCl) derivatization is commonly used for derivatization of primary and secondary amines and phenolic alcohols, though evidence exists that with proper reaction conditions (i.e., specific bases), other hydroxyl groups may be derivatized too. Previous studies have examined BzCl concentration, reaction times, and reaction temperatures for derivatization of amines and phenols for LC-MS analysis; however, use of different bases, base concentration, and extending to conditions to hydroxyl groups for LC-MS analysis has not been well-studied. To address this understudied area and identify reaction conditions for both amino and hydroxyl groups, we performed a systematic study of reaction conditions on multiple classes of potential targets. For selected derivatization methods, detection limits and performance in a variety of biological matrices were assessed. Results highlight the importance of tailoring derivatization methods for a given application as they varied by molecule and/or molecule class. Compared to the standard BzCl method commonly used, alternative methods were identified to better derivatize challenging analytes (glucosamine, choline, cortisol, uridine, cytidine) with detection limits reaching 1100, 9, 38, 170, and 67 nM compared to undetectable, 170, 86, 1000, and 86 nM respectively. Sub-nanomolar detection limits were achieved for norepinephrine with alternative derivatization approaches. Improved derivatization methods for several classes and molecules including nucleosides, steroids, and molecules containing hydroxyl groups were also identified.
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Affiliation(s)
- Ashley E Lenhart
- Department of Chemistry, University of Michigan, Ann Arbor, MI, USA 48109
| | | | - Kaley M Simcox
- Department of Chemistry, University of Michigan, Ann Arbor, MI, USA 48109
| | - Brianna A Ramos
- Department of Neuroscience, University of Michigan, Ann Arbor, MI, USA 48109
| | - Robert T Kennedy
- Department of Chemistry, University of Michigan, Ann Arbor, MI, USA 48109; Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA 48109.
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2
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Lee C, Lee DK, Wei IA, Qiu TA, Rubakhin SS, Roper MG, Sweedler JV. Relations between Glucose and d-Amino Acids in the Modulation of Biochemical and Functional Properties of Rodent Islets of Langerhans. ACS OMEGA 2023; 8:47723-47734. [PMID: 38144114 PMCID: PMC10733910 DOI: 10.1021/acsomega.3c05983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Revised: 11/06/2023] [Accepted: 11/10/2023] [Indexed: 12/26/2023]
Abstract
The cell-to-cell signaling role of d-amino acids (d-AAs) in the mammalian endocrine system, particularly in the islets of Langerhans, has drawn growing interest for their potential involvement in modulating glucose metabolism. Previous studies found colocalization of serine racemase [produces d-serine (d-Ser)] and d-alanine (d-Ala) within insulin-secreting beta cells and d-aspartate (d-Asp) within glucagon-secreting alpha cells. Expressed in the islets, functional N-methyl-d-aspartate receptors are involved in the modulation of glucose-stimulated insulin secretion and have binding sites for several d-AAs. However, knowledge of the regulation of d-AA levels in the islets during glucose stimulation as well as the response of islets to different levels of extracellular d-AAs is limited. In this study, we determined the intracellular and extracellular levels of d-Ser, d-Ala, and d-Asp in cultures of isolated rodent islets exposed to different levels of extracellular glucose. We found that the intracellular levels of the enantiomers demonstrated large variability and, in general, were not affected by extracellular glucose levels. However, significantly lower levels of extracellular d-Ser and d-Ala were observed in the islet media supplemented with 20 mM concentration of glucose compared to the control condition utilizing 3 mM glucose. Glucose-induced oscillations of intracellular free calcium concentration ([Ca2+]i), a proxy for insulin secretion, were modulated by the exogenous application of d-Ser and d-Ala but not by their l-stereoisomers. Our results provide new insights into the roles of d-AAs in the biochemistry and function of pancreatic islets.
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Affiliation(s)
- Cindy
J. Lee
- Department
of Chemistry and the Beckman Institute, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Dong-Kyu Lee
- Department
of Chemistry and the Beckman Institute, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
| | - I-An Wei
- Department
of Chemistry and Biochemistry, Florida State
University, Tallahassee, Florida 32306, United States
| | - Tian A. Qiu
- Department
of Chemistry and the Beckman Institute, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Stanislav S. Rubakhin
- Department
of Chemistry and the Beckman Institute, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Michael G. Roper
- Department
of Chemistry and Biochemistry, Florida State
University, Tallahassee, Florida 32306, United States
| | - Jonathan V. Sweedler
- Department
of Chemistry and the Beckman Institute, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
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Ogunkunle EO, Davis JJ, Skinner EL, Thornham J, Roper MG. Analysis of D-amino acids secreted from murine islets of Langerhans using Marfey's reagent and reversed phase LC-MS/MS. J Chromatogr B Analyt Technol Biomed Life Sci 2023; 1231:123928. [PMID: 37976942 PMCID: PMC10843809 DOI: 10.1016/j.jchromb.2023.123928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 10/22/2023] [Accepted: 11/08/2023] [Indexed: 11/19/2023]
Abstract
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 (R2 > 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 islet-1h-1; D-Gln: 300 ± 100 fmol islet-1h-1) or high (D-Ser: 23 ± 1 fmol islet-1h-1; D-Gln: 120 ± 50 fmol islet-1h-1) 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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Affiliation(s)
- Emmanuel O Ogunkunle
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, FL 32306, United States
| | - Joshua J Davis
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, FL 32306, United States
| | - Emily L Skinner
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, FL 32306, United States
| | - James Thornham
- Program in Molecular Biophysics, Florida State University, 95 Chieftain Way, Tallahassee, FL 32306, United States
| | - Michael G Roper
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, FL 32306, United States; Program in Molecular Biophysics, Florida State University, 95 Chieftain Way, Tallahassee, FL 32306, United States.
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Lenhart A, Kennedy RT. Evaluation of Surface Treatments of PDMS Microfluidic Devices for Improving Small-Molecule Recovery with Application to Monitoring Metabolites Secreted from Islets of Langerhans. ACS MEASUREMENT SCIENCE AU 2023; 3:380-389. [PMID: 37868359 PMCID: PMC10588933 DOI: 10.1021/acsmeasuresciau.3c00025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 07/14/2023] [Accepted: 07/17/2023] [Indexed: 10/24/2023]
Abstract
Microfluidic devices are becoming an important tool for bioanalysis with applications including studying cell secretion, cell growth, and drug delivery. Small molecules such as drugs, cell products, or nutrients may partition into polydimethylsiloxane (PDMS), a commonly used material for microfluidic devices, potentially leading to poor recovery or inaccurate delivery of such chemicals. To decrease small-molecule partitioning, surface and bulk PDMS treatments have been developed; however, these have been tested on few analytes, or their biocompatibility are unknown. Studies often focus on one analyte, whereas a diversity of chemicals are of interest and possibly affected. In this study, 11 device treatments are tested and applied to 21 biologically relevant small molecules with a variety of chemical structures. Device treatments are characterized using water contact angle measurements and evaluated by measuring recovery of the 21 target analytes using liquid chromatography-mass spectrometry. 1,5-Dimethyl-1,5-diazaundecamethylene polymethobromide (polybrene), a positively charged polymer, produced the least hydrophilic surface and was found to provide the best recovery with most of the analytes having >50% recovery and up to 92% recovery; however, recovery varied by analyte highlighting the importance of analyte diversity rather than targeting a single analyte in evaluating treatments. A polybrene-treated device was applied to investigate secretion from pancreatic islets, which are micro-organs involved in glucose homeostasis and diabetes. Islets secrete small molecules that have been shown to modulate the secretion of islets' main functional products, glucose-regulating hormones. The polybrene treatment enabled the detection of 20 target analytes from islets-on-chip during isosmotic and hypo-osmotic glucose perfusions and resulted in detection of more significant secretion changes compared to untreated PDMS.
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Affiliation(s)
- Ashley
E. Lenhart
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Robert T. Kennedy
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department
of Pharmacology, University of Michigan, Ann Arbor, Michigan 48109, United States
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Monitoring hormone and small molecule secretion dynamics from islets-on-chip. Anal Bioanal Chem 2023; 415:533-544. [PMID: 36459167 DOI: 10.1007/s00216-022-04460-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 11/17/2022] [Accepted: 11/22/2022] [Indexed: 12/03/2022]
Abstract
Tissue functions such as hormone secretion involve the interplay of multiple chemical signals and metabolic processes over time. Measuring the different components involved is useful in unraveling the interactions, but often requires use of multiple analytical techniques. The challenge of measuring the necessary components with temporal resolution is greater when tissue samples are limited. Here, an accessible microfluidic platform compatible with multiple measurement techniques to monitor cell secretions has been developed. The platform is applied to islets of Langerhans, micro-organs involved in glucose homeostasis and diabetes. The device houses 1 to 8 islets and the perfusion fluid can be controlled to change conditions, e.g., glucose concentration, in seconds. Samples are collected in fractions and split for offline analysis. The device is paired with a scaled-down immunoassay, AlphaLISA, for hormone quantification and liquid chromatography-mass spectrometry for small molecule quantification to study secretion dynamics. The combined system allows the first simultaneous measurement of insulin, glucagon, biogenic amines, and amino acids from islet secretions. The combined measurements revealed correlation in secretion events and differences in timing of release between hormones and biogenic amines and amino acids. These efforts decreased the number of islets required compared to standard approaches, thus decreasing necessary animal use, reagent use, and cost, while increasing information content achievable from one sample. The microfluidic device is a suitable platform for in-depth characterization of secretion from small tissue samples.
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Lapizco-Encinas BH, Zhang YV. Microfluidic systems in clinical diagnosis. Electrophoresis 2023; 44:217-245. [PMID: 35977346 DOI: 10.1002/elps.202200150] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 08/10/2022] [Accepted: 08/11/2022] [Indexed: 02/01/2023]
Abstract
The use of microfluidic devices is highly attractive in the field of biomedical and clinical assessments, as their portability and fast response time have become crucial in providing opportune therapeutic treatments to patients. The applications of microfluidics in clinical diagnosis and point-of-care devices are continuously growing. The present review article discusses three main fields where miniaturized devices are successfully employed in clinical applications. The quantification of ions, sugars, and small metabolites is examined considering the analysis of bodily fluids samples and the quantification of this type of analytes employing real-time wearable devices. The discussion covers the level of maturity that the devices have reached as well as cost-effectiveness. The analysis of proteins with clinical relevance is presented and organized by the function of the proteins. The last section covers devices that can perform single-cell metabolomic and proteomic assessments. Each section discusses several strategically selected recent reports on microfluidic devices successfully employed for clinical assessments, to provide the reader with a wide overview of the plethora of novel systems and microdevices developed in the last 5 years. In each section, the novel aspects and main contributions of each reviewed report are highlighted. Finally, the conclusions and future outlook section present a summary and speculate on the future direction of the field of miniaturized devices for clinical applications.
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Affiliation(s)
- Blanca H Lapizco-Encinas
- Microscale Bioseparations Laboratory and Biomedical Engineering Department, Rochester Institute of Technology, Rochester, New York, USA
| | - Yan Victoria Zhang
- Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, New York, USA
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