{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T04:42:14Z","timestamp":1790743334964,"version":"4.1.0"},"reference-count":41,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2019,5,18]],"date-time":"2019-05-18T00:00:00Z","timestamp":1558137600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000001","name":"National Science Foundation","doi-asserted-by":"publisher","award":["1611072"],"award-info":[{"award-number":["1611072"]}],"id":[{"id":"10.13039\/100000001","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000001","name":"National Science Foundation","doi-asserted-by":"publisher","award":["141489"],"award-info":[{"award-number":["141489"]}],"id":[{"id":"10.13039\/100000001","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Carbon dots (CDs) are fluorescent nanomaterials used extensively in bioimaging, biosensing and biomedicine. This is due in large part to their biocompatibility, photostability, lower toxicity, and lower cost, compared to inorganic quantum dots or organic dyes. However, little is known about the utility of CDs as separation adjuvants in capillary electrophoresis (CE) separations. CDs were synthesized in-house according to a \u2018bottom-up\u2019 method from citric acid or other simple carbon precursors. To demonstrate the applicability of CDs as separation adjuvants, mixtures of holo- (metallated) and apo- (demetallated) forms of transferrin (Tf, an iron transport protein) were analyzed. In the absence of CDs, the proteins were not resolved by a simple CE method; however, upon addition of CDs to the separation buffer, multiple forms of Tf were resolved indicating that CDs are valuable tools to facilitate the separation of analytes by CE. CE parameters including sample preparation, buffer identity, ionic strength, pH, capillary inside diameter, and temperature were optimized. The results suggest that dots synthesized from citric acid provide the best resolution of various different forms of Tf and that CDs are versatile and promising tools to improve current electrophoretic separation methods, especially for metalloprotein analysis.<\/jats:p>","DOI":"10.3390\/molecules24101916","type":"journal-article","created":{"date-parts":[[2019,5,20]],"date-time":"2019-05-20T11:05:07Z","timestamp":1558350307000},"page":"1916","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":14,"title":["Carbon Dot-Mediated Capillary Electrophoresis Separations of Metallated and Demetallated Forms of Transferrin Protein"],"prefix":"10.3390","volume":"24","author":[{"given":"Leona R.","family":"Sirkisoon","sequence":"first","affiliation":[{"name":"Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Honest C.","family":"Makamba","sequence":"additional","affiliation":[{"name":"Razzberry Inc., 5 Science Park, Unit 2E9, New Haven, CT 06511, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shingo","family":"Saito","sequence":"additional","affiliation":[{"name":"Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3099-6171","authenticated-orcid":false,"given":"Christa L.","family":"Colyer","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2019,5,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Shan, D., Hsieh, J.-T., Bai, X., and Yang, J. (2018). Citrate-based fluorescent biomaterials. Adv. Healthc. Mater., 7.","DOI":"10.1002\/adhm.201800532"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"5401","DOI":"10.1039\/C8CC02279H","article-title":"Dispersibility of carbon dots in aqueous and\/or organic solvents","volume":"54","author":"Zhao","year":"2018","journal-title":"Chem. Commun."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"38","DOI":"10.1016\/j.ab.2016.01.024","article-title":"Graphene quantum dots as additives in capillary electrophoresis for separation cinnamic acid and its derivatives","volume":"500","author":"Sun","year":"2016","journal-title":"Anal. Biochem."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1586","DOI":"10.1039\/C4NR05712K","article-title":"Recent advances in carbon nanodots: Synthesis, properties and biomedical applications","volume":"7","author":"Miao","year":"2015","journal-title":"Nanoscale"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"219","DOI":"10.1016\/j.bios.2014.02.061","article-title":"Synthesis of highly fluorescent nitrogen-doped graphene quantum dots for sensitive, label-free detection of Fe (III) in aqueous media","volume":"58","author":"Ju","year":"2014","journal-title":"Biosens. Bioelectron."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"4738","DOI":"10.1016\/j.carbon.2012.06.002","article-title":"Blue luminescent graphene quantum dots and graphene oxide prepared by tuning the carbonization degree of citric acid","volume":"50","author":"Dong","year":"2012","journal-title":"Carbon"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"12215","DOI":"10.1002\/anie.201206791","article-title":"A biocompatible fluorescent ink based on water-soluble luminescent carbon nanodots","volume":"51","author":"Qu","year":"2012","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"78","DOI":"10.1016\/j.carbon.2017.11.069","article-title":"Carbon dots with red-shifted photoluminescence by fluorine doping for optical bio-imaging","volume":"128","author":"Yang","year":"2018","journal-title":"Carbon"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"2173","DOI":"10.1007\/s00604-015-1541-5","article-title":"Synthesis of fluorescent carbon dots via microwave carbonization of citric acid in presence of tetraoctylammonium ion, and their application to cellular bioimaging","volume":"182","author":"Bhaisare","year":"2015","journal-title":"Microchim. Acta"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"2554","DOI":"10.1021\/bm300796q","article-title":"Bioimaging of hyaluronic acid derivatives using nanosized carbon dots","volume":"13","author":"Goh","year":"2012","journal-title":"Biomacromolecules"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1905","DOI":"10.3762\/bjnano.7.182","article-title":"Facile fabrication of luminescent organic dots by thermolysis of citric acid in urea melt, and their use for cell staining and polyelectrolyte microcapsule labelling","volume":"7","author":"Zholobak","year":"2016","journal-title":"Beilstein J. Nanotechnol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"3554","DOI":"10.1002\/adma.201306192","article-title":"Integrating oxaliplatin with highly luminescent carbon dots: An unprecedented theranostic agent for personalized medicine","volume":"26","author":"Zheng","year":"2014","journal-title":"Adv. Mater."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1130","DOI":"10.1016\/j.snb.2017.08.130","article-title":"Heterogeneous synthesis of nitrogen-doped carbon dots prepared via anhydrous citric acid and melamine for selective and sensitive turn on-off-on detection of Hg (II), glutathione and its cellular imaging","volume":"255","author":"Iqbal","year":"2018","journal-title":"Sens. Actuators B Chem."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"95054","DOI":"10.1039\/C5RA18176C","article-title":"Nitrogen-doped carbon dots as fluorescent probe for detection of curcumin based on the inner filter effect","volume":"5","author":"Zhang","year":"2015","journal-title":"RSC Adv."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"79043","DOI":"10.1039\/C6RA12131D","article-title":"Development of N, S-doped carbon dots as a novel matrix for the analysis of small molecules by negative ion MALDI-TOF MS","volume":"6","author":"Wang","year":"2016","journal-title":"RSC Adv."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"3976","DOI":"10.1002\/jssc.201500810","article-title":"Preparation of chitosan-modified silica nanoparticles and their applications in the separation of auxins by capillary electrophoresis","volume":"38","author":"Duan","year":"2015","journal-title":"J. Sep. Sci."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1297","DOI":"10.1007\/s00604-015-1449-0","article-title":"Amino-functionalized silica nanoparticles for improved enantiomeric separation in capillary electrophoresis using carboxymethyl-beta-cyclodextrin (CM-beta-CD) as a chiral selector","volume":"182","author":"Gong","year":"2015","journal-title":"Microchim. Acta"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1681","DOI":"10.1002\/elps.200900628","article-title":"Evaluation of the performance of singlewalled carbon nanohorns in capillary electrophoresis","volume":"31","author":"Cardenas","year":"2010","journal-title":"Electrophoresis"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"2561","DOI":"10.1002\/elps.201300130","article-title":"Graphene nanoparticles as pseudostationary phase for the electrokinetic separation of nonsteroidal anti-inflammatory drugs","volume":"34","author":"Simonet","year":"2013","journal-title":"Electrophoresis"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1689","DOI":"10.1002\/elps.200900696","article-title":"Separation of flavonoids and phenolic acids in complex natural products by microemulsion electrokinetic chromatography using surfactant-coated and carboxylic single-wall carbon nanotubes as additives","volume":"31","author":"Cao","year":"2010","journal-title":"Electrophoresis"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"5220","DOI":"10.1021\/ac0104375","article-title":"Use of gold nanoparticles to enhance capillary electrophoresis","volume":"73","author":"Neiman","year":"2001","journal-title":"Anal. Chem."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"4595","DOI":"10.1021\/ac0204045","article-title":"Nanoparticles as pseudostationary phase in capillary electrochrornatography\/ESI-MS","volume":"74","author":"Viberg","year":"2002","journal-title":"Anal. Chem."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"588","DOI":"10.1002\/elps.201400440","article-title":"Gold nanomaterials based pseudostationary phases in capillary electrophoresis: A brand-new attempt at chondroitin sulfate isomers separation","volume":"36","author":"Zhao","year":"2015","journal-title":"Electrophoresis"},{"key":"ref_24","unstructured":"Harris, D.C. (2003). Chromatographic methods and capillary electrophoresis. Quantitative Chemical Analysis, W.H. Freeman and Co."},{"key":"ref_25","unstructured":"Skoog, D.A., West, D.M., Holler, F.J., and Crouch, S.R. (2003). Miscellaneous separation methods. Fundamentals of Analytical Chemistry 8th EDITION, Cengage Learning."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"127","DOI":"10.1016\/j.chroma.2013.10.073","article-title":"Separation of iron-free and iron-saturated forms of transferrin and lactoferrin via capillary electrophoresis performed in fused-silica and neutral capillaries","volume":"1321","author":"Nowak","year":"2013","journal-title":"J. Chromatogr. A"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"176","DOI":"10.1016\/j.chroma.2013.08.086","article-title":"Water-compatible surface molecularly imprinted silica nanoparticles as pseudostationary phase in electrokinetic chromatography for the enantioseparation of tryptophan","volume":"1311","author":"Yue","year":"2013","journal-title":"J. Chromatogr. A"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"719","DOI":"10.1002\/jssc.200400076","article-title":"Molecular imprinting technology in capillary electrochromatography","volume":"28","author":"Turiel","year":"2005","journal-title":"J. Sep. Sci."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"5510","DOI":"10.1021\/ac900831u","article-title":"Capillary electrophoresis-assisted identification of peroxyl radical generated by single-walled carbon nanotubes in a cell-free system","volume":"81","author":"Ren","year":"2009","journal-title":"Anal. Chem."},{"key":"ref_30","unstructured":"Lippard, S.J., and Berg, J.M. (1994). Principles of Bioinorganic Chemistry, University Science Books."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"225","DOI":"10.1002\/med.10008","article-title":"Transferrin\/transferrin receptor-mediated drug delivery","volume":"22","author":"Li","year":"2002","journal-title":"Med. Res. Rev."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"24066","DOI":"10.1074\/jbc.274.34.24066","article-title":"Transferrin Trojan horses as a rational approach for the biological delivery of therapeutic peptide domains","volume":"274","author":"Ali","year":"1999","journal-title":"J. Biol. Chem."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"443","DOI":"10.2174\/138161280506230110111312","article-title":"Transferrin as a targeting ligand for liposomes and anticancer drugs","volume":"5","author":"Singh","year":"1999","journal-title":"Curr. Pharm. Des."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"561","DOI":"10.1124\/pr.54.4.561","article-title":"Targeted drug delivery via the transferrin receptor-mediated endocytosis pathway","volume":"54","author":"Qian","year":"2002","journal-title":"Pharmacol. Rev."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"794","DOI":"10.1016\/j.biomaterials.2012.10.003","article-title":"Transferrin receptor specific nanocarriers conjugated with functional 7peptide for oral drug delivery","volume":"34","author":"Du","year":"2013","journal-title":"Biomaterials"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"222","DOI":"10.1038\/cgt.2013.9","article-title":"Transferrin receptor targeting nanomedicine delivering wild-type p53 gene sensitizes pancreatic cancer to gemcitabine therapy","volume":"20","author":"Camp","year":"2013","journal-title":"Cancer Gene Ther."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"39","DOI":"10.1016\/j.jinorgbio.2010.09.005","article-title":"Interactions of arene-Ru(II)-chloroquine complexes of known antimalarial and antitumor activity with human serum albumin (HSA) and transferrin","volume":"105","author":"Martinez","year":"2011","journal-title":"J. Inorg. Biochem."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"291","DOI":"10.1007\/s00232-014-9637-0","article-title":"Transferrin receptor-mediated endocytosis: A useful target for cancer therapy","volume":"247","author":"Tortorella","year":"2014","journal-title":"J. Membr. Biol."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"5148","DOI":"10.1039\/C5CP05890B","article-title":"Luminescence turn-on\/off sensing of biological iron by carbon dots in transferrin","volume":"18","author":"Bhattacharya","year":"2016","journal-title":"Phys. Chem. Chem. Phys."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1016\/j.chroma.2014.03.037","article-title":"Selective separation of ferric and non-ferric forms of human transferrin by capillary micellar electrokinetic chromatography","volume":"1341","author":"Nowak","year":"2014","journal-title":"J. Chromatogr. A"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"3953","DOI":"10.1002\/anie.201300519","article-title":"Highly photoluminescent carbon dots for multicolor patterning, sensors, and bioimaging","volume":"52","author":"Zhu","year":"2013","journal-title":"Angew. Chem. Int. Ed."}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/24\/10\/1916\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T12:53:20Z","timestamp":1760187200000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/24\/10\/1916"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,5,18]]},"references-count":41,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2019,5]]}},"alternative-id":["molecules24101916"],"URL":"https:\/\/doi.org\/10.3390\/molecules24101916","relation":{},"ISSN":["1420-3049"],"issn-type":[{"value":"1420-3049","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,5,18]]}}}