Acid Dissociation of 3-Mercaptopropionic Acid Coated CdSe-CdS/Cd0.5Zn0.5S/ZnS Core-Multishell Quantum Dot and Strong Ionic Interaction with Ca2+ Ion
2016 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 6, 3519-3529 p.Article in journal (Refereed) PublishedText
By devising careful electrophoresis, it was shown that at pH below 7.0, the electrophoretic mobility of 3-mercaptopropionic acid (3MPA) coated CdSe-ZnS core-shell quantum dots (denoted as QD-3MPA) was very small. At pH above 7.0, QD-3MPA migrated toward the anode, implying acid dissociation, and the degree of which was proportional to the pH value. QD-3MPA's electrophoretic mobility was impaired after adding sufficient Ca2+ ions to the QD solution and revived when a similar amount of Ca2+ chelators (ethylene glycol tetraacetic acid, EGTA) was added. This demonstrated that acid dissociation and its pH dependence of 3MPA on the QD surface are critical factors in understanding the electric and optical properties of QDs. The acid dissociated QD-3MPA interacted strongly with Ca2+, forming a charge neutral QD-3MPA Ca2+ complex in the absence of EGTA. First-principles study confirmed the observed experimental evidence. The strong ionic interaction between acid dissociated QD-3MPA and Ca2+ is critical for developing reliable QD-based biosensing assays. Moreover, the strategy and techniques reported in this work are easily applicable to other fluorescent biomarkers and therefore can be important for advancing in vivo and in vitro imaging, sensing, and labeling.
Place, publisher, year, edition, pages
American Chemical Society (ACS), 2016. Vol. 120, no 6, 3519-3529 p.
Engineering and Technology
IdentifiersURN: urn:nbn:se:kth:diva-184037DOI: 10.1021/acs.jpcc.5b11023ISI: 000370678700047ScopusID: 2-s2.0-84959017599OAI: oai:DiVA.org:kth-184037DiVA: diva2:914394
QC 201603232016-03-232016-03-222016-03-23Bibliographically approved