{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,8]],"date-time":"2026-07-08T16:23:46Z","timestamp":1783527826018,"version":"3.55.0"},"reference-count":65,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2026,6,22]],"date-time":"2026-06-22T00:00:00Z","timestamp":1782086400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"US NIH","award":["5R01GM131008"],"award-info":[{"award-number":["5R01GM131008"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Membranes"],"abstract":"<jats:p>Integral membrane proteins (IMPs), which constitute 50\u201360% of drug targets, play essential roles in numerous biological processes but remain underrepresented in conventional bottom-up and structural proteomics owing to their hydrophobicity and resistance to proteolysis. Although advances in IMP proteomics have improved global IMP detection, most efforts focus on proteome-scale protein identification rather than targeted structural analysis. Protein footprinting and cross-linking, two approaches in structural proteomics, require high sequence coverage and protein digestion to peptides of suitable length for structural elucidation, necessitating optimized digestion condition for individual IMPs. Here, we report a digestion protocol tailored for structural mass spectrometry and evaluate its performance by using a single amphipathic IMP model featuring distinct extramembrane and transmembrane domains. We evaluated the use of various protease\u2013additive combinations and applied filter-aided sample preparation (FASP) to remove detergents and surfactants efficiently prior to MS analysis. The optimized conditions consistently yielded &gt;90% sequence coverage. Guided by MS retention time calibration and hydrophobic factor simulations, we identified a \u201csweet spot\u201d for transmembrane peptide detection. Notably, although cleavable surfactants can enhance proteome-wide coverage, our results show that they are not essential for single protein studies as they are in structural proteomics. Instead, detergent removal, protease selection, and generation of suitably sized peptides are critical for enabling reliable bottom-up structural analysis of IMPs. The protocol developed here provides a practical framework for optimizing digestion conditions in IMP characterization.<\/jats:p>","DOI":"10.3390\/membranes16060215","type":"journal-article","created":{"date-parts":[[2026,6,23]],"date-time":"2026-06-23T08:19:52Z","timestamp":1782202792000},"page":"215","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Optimized Digestion Conditions for Membrane Protein Footprinting and Mass Spectrometry Analysis"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1581-6382","authenticated-orcid":false,"given":"Ming","family":"Cheng","sequence":"first","affiliation":[{"name":"Shandong Laboratory of Yantai Drug Discovery, Bohai Rim Advanced Research Institute for Drug Discovery, Yantai 264117, China"},{"name":"Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xinzhu","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Washington University, St. Louis, MO 63130, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lin","family":"Bai","sequence":"additional","affiliation":[{"name":"Shandong Laboratory of Yantai Drug Discovery, Bohai Rim Advanced Research Institute for Drug Discovery, Yantai 264117, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Weikai","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Biochemistry and Molecular Biophysics, Washington University, St. Louis, MO 63130, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michael L.","family":"Gross","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Washington University, St. Louis, MO 63130, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,6,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1146\/annurev-bioeng-092115-025322","article-title":"Drugging Membrane Protein Interactions","volume":"18","author":"Yin","year":"2016","journal-title":"Annu. Rev. Biomed. Eng."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"324","DOI":"10.1038\/aps.2011.187","article-title":"Ice breaking in GPCR structural biology","volume":"33","author":"Zhao","year":"2012","journal-title":"Acta Pharmacol. Sin."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"165","DOI":"10.1021\/acs.accounts.4c00545","article-title":"Mass Spectrometry-Based Protein Footprinting for Protein Structure Characterization","volume":"58","author":"Cheng","year":"2025","journal-title":"Acc. Chem. Res."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"583","DOI":"10.1021\/acs.analchem.0c04342","article-title":"Native Mass Spectrometry of Membrane Proteins","volume":"93","author":"Keener","year":"2021","journal-title":"Anal. Chem."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Yang, H.-C., Li, W., Sun, J., and Gross, M.L. (2023). Advances in Mass Spectrometry on Membrane Proteins. Membranes, 13.","DOI":"10.3390\/membranes13050457"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"639","DOI":"10.1038\/nprot.2013.024","article-title":"Mass spectrometry of intact membrane protein complexes","volume":"8","author":"Laganowsky","year":"2013","journal-title":"Nat. Protoc."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1016\/j.ymeth.2018.02.020","article-title":"Mass spectrometry-enabled structural biology of membrane proteins","volume":"147","author":"Calabrese","year":"2018","journal-title":"Methods"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"2709","DOI":"10.1021\/acs.analchem.5c04456","article-title":"Multiplexed Isotope-Coded Mass Spectrometry Footprinting Enables Broad Heteroatom-Residue Mapping and Uncovers Noncanonical Ligand-Binding Sites in Amyloidosis Proteins","volume":"98","author":"Yang","year":"2026","journal-title":"Anal. Chem."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"2558","DOI":"10.1021\/ac303064a","article-title":"Integral Membrane Proteins and Bilayer Proteomics","volume":"85","author":"Whitelegge","year":"2013","journal-title":"Anal. Chem."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"S174","DOI":"10.1002\/elps.200900050","article-title":"Membrane proteins and proteomics: Love is possible, but so difficult","volume":"30","author":"Rabilloud","year":"2009","journal-title":"Electrophoresis"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1016\/j.jprot.2016.08.006","article-title":"Integral membrane proteins in proteomics. How to break open the black box?","volume":"153","author":"Vit","year":"2017","journal-title":"J. Proteom."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"4036","DOI":"10.1002\/pmic.200800143","article-title":"A practical guide for the identification of membrane and plasma membrane proteins in human embryonic stem cells and human embryonal carcinoma cells","volume":"8","author":"Dormeyer","year":"2008","journal-title":"Proteomics"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1551","DOI":"10.1021\/ac403185a","article-title":"Combine and conquer: Surfactants, solvents, and chaotropes for robust mass spectrometry based analyses of membrane proteins","volume":"86","author":"Waas","year":"2014","journal-title":"Anal. Chem."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"5179","DOI":"10.1021\/acs.analchem.6b04232","article-title":"In-Depth Proteome Coverage by Improving Efficiency for Membrane Proteome Analysis","volume":"89","author":"Zhao","year":"2017","journal-title":"Anal. Chem."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"7544","DOI":"10.1021\/ac5013267","article-title":"1-Dodecyl-3-methylimidazolium chloride-assisted sample preparation method for efficient integral membrane proteome analysis","volume":"86","author":"Zhao","year":"2014","journal-title":"Anal. Chem."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"6023","DOI":"10.1021\/ac0346196","article-title":"Enzyme-friendly, mass spectrometry-compatible surfactant for in-solution enzymatic digestion of proteins","volume":"75","author":"Yu","year":"2003","journal-title":"Anal. Chem."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"6642","DOI":"10.1021\/ac034802z","article-title":"Mass Spectrometry of Intracellular and Membrane Proteins Using Cleavable Detergents","volume":"75","author":"Norris","year":"2003","journal-title":"Anal. Chem."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"114924","DOI":"10.1016\/j.ab.2022.114924","article-title":"Maximizing hydrophobic peptide recovery in proteomics and antibody development using a mass spectrometry compatible surfactant","volume":"658","author":"Nie","year":"2022","journal-title":"Anal. Biochem."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1654","DOI":"10.1002\/pmic.200600579","article-title":"Differential recovery of membrane proteins after extraction by aqueous methanol and trifluoroethanol","volume":"7","author":"Zhang","year":"2007","journal-title":"Proteomics"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"8507","DOI":"10.1021\/ac402076u","article-title":"Biphasic microreactor for efficient membrane protein pretreatment with a combination of formic acid assisted solubilization, on-column pH adjustment, reduction, alkylation, and tryptic digestion","volume":"85","author":"Zhao","year":"2013","journal-title":"Anal. Chem."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"6181","DOI":"10.1021\/ac301169q","article-title":"Microwave-assisted protein solubilization for mass spectrometry-based shotgun proteome analysis","volume":"84","author":"Ye","year":"2012","journal-title":"Anal. Chem."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"3935","DOI":"10.1002\/pmic.201000289","article-title":"Subcellular fractionation methods and strategies for proteomics","volume":"10","author":"Lee","year":"2010","journal-title":"Proteomics"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"2434","DOI":"10.1021\/acs.analchem.7b03710","article-title":"Enhancing Membrane Protein Identification Using a Simplified Centrifugation and Detergent-Based Membrane Extraction Approach","volume":"90","author":"Zhou","year":"2018","journal-title":"Anal. Chem."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"5065","DOI":"10.1021\/acs.analchem.6b01082","article-title":"Glycan Moieties as Bait to Fish Plasma Membrane Proteins","volume":"88","author":"Fang","year":"2016","journal-title":"Anal. Chem."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"378","DOI":"10.1038\/nbt.1532","article-title":"Mass-spectrometric identification and relative quantification of N-linked cell surface glycoproteins","volume":"27","author":"Wollscheid","year":"2009","journal-title":"Nat. Biotechnol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1817","DOI":"10.1021\/ac0354037","article-title":"Proteomic Analysis of Integral Plasma Membrane Proteins","volume":"76","author":"Zhao","year":"2004","journal-title":"Anal. Chem."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"7720","DOI":"10.1021\/acs.analchem.5b01187","article-title":"Rescuing Those Left Behind: Recovering and Characterizing Underdigested Membrane and Hydrophobic Proteins to Enhance Proteome Measurement Depth","volume":"87","author":"Giannone","year":"2015","journal-title":"Anal. Chem."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"4984","DOI":"10.1021\/acs.analchem.2c05222","article-title":"Investigating Daptomycin\u2013Membrane Interactions Using Native MS and Fast Photochemical Oxidation of Peptides in Nanodiscs","volume":"95","author":"Reid","year":"2023","journal-title":"Anal. Chem."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"14367","DOI":"10.1073\/pnas.0901074106","article-title":"Structural waters define a functional channel mediating activation of the GPCR, rhodopsin","volume":"106","author":"Angel","year":"2009","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"889","DOI":"10.1007\/s13361-012-0342-x","article-title":"Validation of membrane protein topology models by oxidative labeling and mass spectrometry","volume":"23","author":"Pan","year":"2012","journal-title":"J. Am. Soc. Mass Spectrom."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"50","DOI":"10.1007\/s13361-016-1421-1","article-title":"FPOP-LC-MS\/MS Suggests Differences in Interaction Sites of Amphipols and Detergents with Outer Membrane Proteins","volume":"28","author":"Watkinson","year":"2017","journal-title":"J. Am. Soc. Mass Spectrom."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"6134","DOI":"10.1073\/pnas.0901691106","article-title":"Membrane orientation of the FMO antenna protein from Chlorobaculum tepidum as determined by mass spectrometry-based footprinting","volume":"106","author":"Wen","year":"2009","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"14873","DOI":"10.1002\/anie.201708254","article-title":"Carbene Footprinting Reveals Binding Interfaces of a Multimeric Membrane-Spanning Protein","volume":"56","author":"Manzi","year":"2017","journal-title":"Angew. Chem. Int. Ed. Engl."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1002\/mas.21667","article-title":"MEMBRANE PROTEIN STRUCTURES AND INTERACTIONS FROM COVALENT LABELING COUPLED WITH MASS SPECTROMETRY","volume":"41","author":"Pan","year":"2022","journal-title":"Mass Spectrom. Rev."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"7178","DOI":"10.1021\/acs.analchem.2c05616","article-title":"Membrane Protein Binding Interactions Studied in Live Cells via Diethylpyrocarbonate Covalent Labeling Mass Spectrometry","volume":"95","author":"Kirsch","year":"2023","journal-title":"Anal. Chem."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"14007","DOI":"10.1002\/anie.201706697","article-title":"Laser-Initiated Radical Trifluoromethylation of Peptides and Proteins: Application to Mass-Spectrometry-Based Protein Footprinting","volume":"56","author":"Cheng","year":"2017","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"e202424779","DOI":"10.1002\/anie.202424779","article-title":"In-Cell Fast Photochemical Oxidation Interrogates the Native Structure of Integral Membrane Proteins","volume":"64","author":"Sun","year":"2025","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1100","DOI":"10.1021\/ac902484p","article-title":"Dynamics of the \u03b22-Adrenergic G-Protein Coupled Receptor Revealed by Hydrogen\u2212Deuterium Exchange","volume":"82","author":"Zhang","year":"2010","journal-title":"Anal. Chem."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"11406","DOI":"10.1021\/acs.analchem.1c01171","article-title":"Hydrogen\u2013Deuterium Exchange Mass Spectrometry with Integrated Size-Exclusion Chromatography for Analysis of Complex Protein Samples","volume":"93","author":"Calvaresi","year":"2021","journal-title":"Anal. Chem."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"10970","DOI":"10.1021\/acs.analchem.9b00973","article-title":"Improving the Sequence Coverage of Integral Membrane Proteins during Hydrogen\/Deuterium Exchange Mass Spectrometry Experiments","volume":"91","author":"Slivacka","year":"2019","journal-title":"Anal. Chem."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"4151","DOI":"10.1038\/s41467-018-06704-1","article-title":"Direct protein-lipid interactions shape the conformational landscape of secondary transporters","volume":"9","author":"Martens","year":"2018","journal-title":"Nat. Commun."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1038\/nsmb.3333","article-title":"Warfarin traps human vitamin K epoxide reductase in an intermediate state during electron transfer","volume":"24","author":"Shen","year":"2017","journal-title":"Nat. Struct. Mol. Biol."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"12060","DOI":"10.1021\/acs.analchem.6b02502","article-title":"Probing the Lysine Proximal Microenvironments within Membrane Protein Complexes by Active Dimethyl Labeling and Mass Spectrometry","volume":"88","author":"Zhou","year":"2016","journal-title":"Anal. Chem."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"359","DOI":"10.1038\/nmeth.1322","article-title":"Universal sample preparation method for proteome analysis","volume":"6","author":"Zougman","year":"2009","journal-title":"Nat. Methods"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"8867","DOI":"10.1002\/anie.202014096","article-title":"Free-Radical Membrane Protein Footprinting by Photolysis of Perfluoroisopropyl Iodide Partitioned to Detergent Micelle by Sonication","volume":"60","author":"Cheng","year":"2021","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"13101","DOI":"10.1021\/acs.analchem.1c03274","article-title":"Carbocation Footprinting of Soluble and Transmembrane Proteins","volume":"93","author":"Sun","year":"2021","journal-title":"Anal. Chem."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"7270","DOI":"10.1038\/s41467-021-27588-8","article-title":"Nanoparticles and photochemistry for native-like transmembrane protein footprinting","volume":"12","author":"Sun","year":"2021","journal-title":"Nat. Commun."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"2636","DOI":"10.1021\/jasms.1c00172","article-title":"Diethylpyrocarbonate Footprints a Membrane Protein in Micelles","volume":"32","author":"Guo","year":"2021","journal-title":"J. Am. Soc. Mass Spectrom."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"507","DOI":"10.1038\/nature08720","article-title":"Structure of a bacterial homologue of vitamin K epoxide reductase","volume":"463","author":"Li","year":"2010","journal-title":"Nature"},{"key":"ref_50","first-page":"15","article-title":"Chapter Two\u2014Filter-Aided Sample Preparation: The Versatile and Efficient Method for Proteomic Analysis","volume":"Volume 585","author":"Shukla","year":"2017","journal-title":"Proteomics in Biology, Part A"},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"993","DOI":"10.1038\/nprot.2016.057","article-title":"Six alternative proteases for mass spectrometry\u2013based proteomics beyond trypsin","volume":"11","author":"Giansanti","year":"2016","journal-title":"Nat. Protoc."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"13.20.1","DOI":"10.1002\/0471250953.bi1320s40","article-title":"Byonic: Advanced peptide and protein identification software","volume":"40","author":"Bern","year":"2012","journal-title":"Curr. Protoc. Bioinform."},{"key":"ref_53","first-page":"D543","article-title":"The PRIDE database at 20 years: 2025 update","volume":"53","author":"Bandla","year":"2024","journal-title":"Nucleic Acids Res."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"1742","DOI":"10.1002\/pmic.200401063","article-title":"Sample preparation and digestion for proteomic analyses using spin filters","volume":"5","author":"Manza","year":"2005","journal-title":"Proteomics"},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"807","DOI":"10.1021\/pr049945w","article-title":"Proteolysis and Mass Spectrometric Analysis of an Integral Membrane:\u2009 Aquaporin 0","volume":"3","author":"Han","year":"2004","journal-title":"J. Proteome. Res."},{"key":"ref_56","first-page":"M110.001479","article-title":"Pressurized Pepsin Digestion in Proteomics","volume":"10","author":"Petritis","year":"2011","journal-title":"Mol. Cell. Proteom."},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"2874","DOI":"10.1039\/C7AN00662D","article-title":"Bottom-up hydrogen deuterium exchange mass spectrometry: Data analysis and interpretation","volume":"142","author":"Brown","year":"2017","journal-title":"Analyst"},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"862","DOI":"10.1021\/pr049927e","article-title":"Analysis of Murine Natural Killer Cell Microsomal Proteins Using Two-Dimensional Liquid Chromatography Coupled to Tandem Electrospray Ionization Mass Spectrometry","volume":"3","author":"Blonder","year":"2004","journal-title":"J. Proteome Res."},{"key":"ref_59","first-page":"258","article-title":"Evaluation of Rapigest Efficacy for the Digestion of Proteins from Cell Cultures and Heart Tissue","volume":"87","author":"Pop","year":"2014","journal-title":"Clujul Med."},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"10880","DOI":"10.1038\/s41598-021-90087-9","article-title":"A comparative study of synthetic winged peptides for absolute protein quantification","volume":"11","author":"Benesova","year":"2021","journal-title":"Sci. Rep."},{"key":"ref_61","doi-asserted-by":"crossref","unstructured":"Zhu, Q., Xue, J., Wang, P., Wang, X., Zhang, J., Fang, X., He, Z., and Wu, F. (2023). Identification of a Novel ACE Inhibitory Hexapeptide from Camellia Seed Cake and Evaluation of Its Stability. Foods, 12.","DOI":"10.3390\/foods12030501"},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"1933","DOI":"10.1021\/pr060525b","article-title":"Membrane Proteomic Analysis of Arabidopsis thaliana Using Alternative Solubilization Techniques","volume":"6","author":"Mitra","year":"2007","journal-title":"J. Proteome Res."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"307","DOI":"10.1016\/j.ab.2010.12.004","article-title":"Comparison of ultrafiltration units for proteomic and N-glycoproteomic analysis by the filter-aided sample preparation method","volume":"410","author":"Zielinska","year":"2011","journal-title":"Anal. Biochem."},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"2700","DOI":"10.1021\/jasms.3c00272","article-title":"Precursor Reagent Hydrophobicity Affects Membrane Protein Footprinting","volume":"34","author":"Guo","year":"2023","journal-title":"J. Am. Soc. Mass Spectrom."},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"1393","DOI":"10.1021\/ac0617013","article-title":"Lookup Peaks:\u2009 A Hybrid of de Novo Sequencing and Database Search for Protein Identification by Tandem Mass Spectrometry","volume":"79","author":"Bern","year":"2007","journal-title":"Anal. Chem."}],"container-title":["Membranes"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2077-0375\/16\/6\/215\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,8]],"date-time":"2026-07-08T16:02:08Z","timestamp":1783526528000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2077-0375\/16\/6\/215"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,6,22]]},"references-count":65,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2026,6]]}},"alternative-id":["membranes16060215"],"URL":"https:\/\/doi.org\/10.3390\/membranes16060215","relation":{},"ISSN":["2077-0375"],"issn-type":[{"value":"2077-0375","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,6,22]]}}}