Acid Dissociation of 3-Mercaptopropionic Acid Coated CdSe-CdS/Cd0.5Zn0.5S/ZnS Core-Multishell Quantum Dot and Strong Ionic Interaction with Ca2+ Ion

• 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.

Ämnesord

NATURVETENSKAP  -- Kemi -- Fysikalisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Physical Chemistry (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Nanoteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Nano-technology (hsv//eng)

Nyckelord

initio molecular-dynamics

augmented-wave method

selective detection

fluorescence

energies

density

probes

water

approximation

nanocrystals

Chemistry

Science & Technology - Other Topics

Materials Science

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)