The adverse role of excess negative ions in reducing the photoluminescence from water soluble MAA-CdSe/ZnS quantum dots in various phosphate buffers

Madeeha Chaudhry, Dong-Kwon Lim, Raheel Qamar, Arshad Saleem Bhatti

Research output: Contribution to journalArticle

Abstract

The use of CdSe/ZnS quantum dots in making biosensors or biomarkers requires them to be water soluble, which can be achieved by conjugating with MAA. We report observation of modulation in the photoluminescence intensities of MAA conjugated CdSe/ZnS QDs (MAA-QDs) that depended strongly on the types and quantity of negative ions present in various kinds of phosphate buffers. The deterioration of PL was attributed to the presence of excess ions in the media that altered the energy and occupation of HOMO and LUMO levels of MAA. Instantaneously, strong reduction in the PL intensity with pH was observed. MAA-QDs incubated for more than 24 hours in the phosphate buffer at pH ∼ 7.0-8.0 showed recovery and enhanced PL intensity, which was attributed to the presence of excess positive ions and a small amount of OH - . Saline buffers showed no significant recovery due to the presence of additional Cl - ions. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were successfully employed to determine the band edges of the MAA-QD system in the presence of excess positive or negative ions (Na + , H + , Cl - , and OH - ) in the media. Thus, it is very important to have complete knowledge of the ions present in the buffer when using MAA-QDs for biomarking or biosensing applications.

Original languageEnglish
Pages (from-to)29446-29451
Number of pages6
JournalPhysical Chemistry Chemical Physics
Volume20
Issue number46
DOIs
Publication statusPublished - 2018 Jan 1

Fingerprint

Quantum Dots
negative ions
Semiconductor quantum dots
Photoluminescence
phosphates
Buffers
Negative ions
buffers
Phosphates
quantum dots
Ions
photoluminescence
Water
positive ions
water
Positive ions
recovery
Recovery
ions
biomarkers

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

The adverse role of excess negative ions in reducing the photoluminescence from water soluble MAA-CdSe/ZnS quantum dots in various phosphate buffers. / Chaudhry, Madeeha; Lim, Dong-Kwon; Qamar, Raheel; Bhatti, Arshad Saleem.

In: Physical Chemistry Chemical Physics, Vol. 20, No. 46, 01.01.2018, p. 29446-29451.

Research output: Contribution to journalArticle

@article{67840f30afe14bc0a6829e0aa48e5e39,
title = "The adverse role of excess negative ions in reducing the photoluminescence from water soluble MAA-CdSe/ZnS quantum dots in various phosphate buffers",
abstract = "The use of CdSe/ZnS quantum dots in making biosensors or biomarkers requires them to be water soluble, which can be achieved by conjugating with MAA. We report observation of modulation in the photoluminescence intensities of MAA conjugated CdSe/ZnS QDs (MAA-QDs) that depended strongly on the types and quantity of negative ions present in various kinds of phosphate buffers. The deterioration of PL was attributed to the presence of excess ions in the media that altered the energy and occupation of HOMO and LUMO levels of MAA. Instantaneously, strong reduction in the PL intensity with pH was observed. MAA-QDs incubated for more than 24 hours in the phosphate buffer at pH ∼ 7.0-8.0 showed recovery and enhanced PL intensity, which was attributed to the presence of excess positive ions and a small amount of OH - . Saline buffers showed no significant recovery due to the presence of additional Cl - ions. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were successfully employed to determine the band edges of the MAA-QD system in the presence of excess positive or negative ions (Na + , H + , Cl - , and OH - ) in the media. Thus, it is very important to have complete knowledge of the ions present in the buffer when using MAA-QDs for biomarking or biosensing applications.",
author = "Madeeha Chaudhry and Dong-Kwon Lim and Raheel Qamar and Bhatti, {Arshad Saleem}",
year = "2018",
month = "1",
day = "1",
doi = "10.1039/c8cp06213g",
language = "English",
volume = "20",
pages = "29446--29451",
journal = "Physical Chemistry Chemical Physics",
issn = "1463-9076",
publisher = "Royal Society of Chemistry",
number = "46",

}

TY - JOUR

T1 - The adverse role of excess negative ions in reducing the photoluminescence from water soluble MAA-CdSe/ZnS quantum dots in various phosphate buffers

AU - Chaudhry, Madeeha

AU - Lim, Dong-Kwon

AU - Qamar, Raheel

AU - Bhatti, Arshad Saleem

PY - 2018/1/1

Y1 - 2018/1/1

N2 - The use of CdSe/ZnS quantum dots in making biosensors or biomarkers requires them to be water soluble, which can be achieved by conjugating with MAA. We report observation of modulation in the photoluminescence intensities of MAA conjugated CdSe/ZnS QDs (MAA-QDs) that depended strongly on the types and quantity of negative ions present in various kinds of phosphate buffers. The deterioration of PL was attributed to the presence of excess ions in the media that altered the energy and occupation of HOMO and LUMO levels of MAA. Instantaneously, strong reduction in the PL intensity with pH was observed. MAA-QDs incubated for more than 24 hours in the phosphate buffer at pH ∼ 7.0-8.0 showed recovery and enhanced PL intensity, which was attributed to the presence of excess positive ions and a small amount of OH - . Saline buffers showed no significant recovery due to the presence of additional Cl - ions. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were successfully employed to determine the band edges of the MAA-QD system in the presence of excess positive or negative ions (Na + , H + , Cl - , and OH - ) in the media. Thus, it is very important to have complete knowledge of the ions present in the buffer when using MAA-QDs for biomarking or biosensing applications.

AB - The use of CdSe/ZnS quantum dots in making biosensors or biomarkers requires them to be water soluble, which can be achieved by conjugating with MAA. We report observation of modulation in the photoluminescence intensities of MAA conjugated CdSe/ZnS QDs (MAA-QDs) that depended strongly on the types and quantity of negative ions present in various kinds of phosphate buffers. The deterioration of PL was attributed to the presence of excess ions in the media that altered the energy and occupation of HOMO and LUMO levels of MAA. Instantaneously, strong reduction in the PL intensity with pH was observed. MAA-QDs incubated for more than 24 hours in the phosphate buffer at pH ∼ 7.0-8.0 showed recovery and enhanced PL intensity, which was attributed to the presence of excess positive ions and a small amount of OH - . Saline buffers showed no significant recovery due to the presence of additional Cl - ions. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were successfully employed to determine the band edges of the MAA-QD system in the presence of excess positive or negative ions (Na + , H + , Cl - , and OH - ) in the media. Thus, it is very important to have complete knowledge of the ions present in the buffer when using MAA-QDs for biomarking or biosensing applications.

UR - http://www.scopus.com/inward/record.url?scp=85057256086&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85057256086&partnerID=8YFLogxK

U2 - 10.1039/c8cp06213g

DO - 10.1039/c8cp06213g

M3 - Article

C2 - 30452035

AN - SCOPUS:85057256086

VL - 20

SP - 29446

EP - 29451

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

SN - 1463-9076

IS - 46

ER -