(CdSe)ZnS quantum dots and organophosphorus hydrolase bioconjugate as biosensors for detection of paraoxon

Xiaojun Ji, Jiayin Zheng, Jianmin Xu, Vipin K. Rastogi, Tu Chen Cheng, Joseph J. DeFrank, Roger Leblanc

Research output: Contribution to journalArticle

224 Citations (Scopus)

Abstract

In this paper, we first report a novel biosensor for the detection of paraoxon based on (CdSe)ZnS core - shell quantum dots (QDs) and an organophosphorus hydrolase (OPH) bioconjugate. The OPH was coupled to (CdSe)ZnS core - shell QDs through electrostatic interaction between negatively charged QDs surfaces and the positively charged protein side chain and ending groups ( - NH 2). Circular dichroism (CD) spectroscopy showed no significant change in the secondary structure of OPH after the bioconjugation, which indicates that the activity of OPH was preserved. Detectable secondary structure changes were observed by CD spectroscopy when the OPH/QDs bioconjugate was exposed to organophosphorus compounds such as paraoxon. Photoluminescence (PL) spectroscopic study showed that the PL intensity of the OPH/QDs bioconjugate was quenched in the presence of paraoxon. The overall quenching percentage as a function of paraoxon concentration matched very well with the Michaelis - Menten equation. This result indicated that the quenching of PL intensity was caused by the conformational change in the enzyme, which is confirmed by CD measurements. The detection limit of paraoxon concentration using OPH/QDs bioconjugate was about 10 -8 M. Although increasing the OPH molar ratio in the bioconjugates will slightly increase the sensitivity of biosensor, no further increase of sensitivity was achieved when the molar ratio of OPH to QDs was greater than 20 because the surface of QDs was saturated by OPH. These properties make the OPH/QDs bioconjugate a promising biosensor for the detection of organophosphorus compounds.

Original languageEnglish
Pages (from-to)3793-3799
Number of pages7
JournalJournal of Physical Chemistry B
Volume109
Issue number9
DOIs
StatePublished - Mar 10 2005

Fingerprint

Paraoxon
Aryldialkylphosphatase
Hydrolases
bioinstrumentation
Biosensors
Semiconductor quantum dots
quantum dots
dichroism
Organophosphorus Compounds
Circular dichroism spectroscopy
Photoluminescence
photoluminescence
quenching
Quenching
sensitivity
spectroscopy
Dichroism
enzymes
Coulomb interactions
electrostatics

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

(CdSe)ZnS quantum dots and organophosphorus hydrolase bioconjugate as biosensors for detection of paraoxon. / Ji, Xiaojun; Zheng, Jiayin; Xu, Jianmin; Rastogi, Vipin K.; Cheng, Tu Chen; DeFrank, Joseph J.; Leblanc, Roger.

In: Journal of Physical Chemistry B, Vol. 109, No. 9, 10.03.2005, p. 3793-3799.

Research output: Contribution to journalArticle

Ji, Xiaojun ; Zheng, Jiayin ; Xu, Jianmin ; Rastogi, Vipin K. ; Cheng, Tu Chen ; DeFrank, Joseph J. ; Leblanc, Roger. / (CdSe)ZnS quantum dots and organophosphorus hydrolase bioconjugate as biosensors for detection of paraoxon. In: Journal of Physical Chemistry B. 2005 ; Vol. 109, No. 9. pp. 3793-3799.
@article{6758e68d9dbc4314a4fa0f6d3c648960,
title = "(CdSe)ZnS quantum dots and organophosphorus hydrolase bioconjugate as biosensors for detection of paraoxon",
abstract = "In this paper, we first report a novel biosensor for the detection of paraoxon based on (CdSe)ZnS core - shell quantum dots (QDs) and an organophosphorus hydrolase (OPH) bioconjugate. The OPH was coupled to (CdSe)ZnS core - shell QDs through electrostatic interaction between negatively charged QDs surfaces and the positively charged protein side chain and ending groups ( - NH 2). Circular dichroism (CD) spectroscopy showed no significant change in the secondary structure of OPH after the bioconjugation, which indicates that the activity of OPH was preserved. Detectable secondary structure changes were observed by CD spectroscopy when the OPH/QDs bioconjugate was exposed to organophosphorus compounds such as paraoxon. Photoluminescence (PL) spectroscopic study showed that the PL intensity of the OPH/QDs bioconjugate was quenched in the presence of paraoxon. The overall quenching percentage as a function of paraoxon concentration matched very well with the Michaelis - Menten equation. This result indicated that the quenching of PL intensity was caused by the conformational change in the enzyme, which is confirmed by CD measurements. The detection limit of paraoxon concentration using OPH/QDs bioconjugate was about 10 -8 M. Although increasing the OPH molar ratio in the bioconjugates will slightly increase the sensitivity of biosensor, no further increase of sensitivity was achieved when the molar ratio of OPH to QDs was greater than 20 because the surface of QDs was saturated by OPH. These properties make the OPH/QDs bioconjugate a promising biosensor for the detection of organophosphorus compounds.",
author = "Xiaojun Ji and Jiayin Zheng and Jianmin Xu and Rastogi, {Vipin K.} and Cheng, {Tu Chen} and DeFrank, {Joseph J.} and Roger Leblanc",
year = "2005",
month = "3",
day = "10",
doi = "10.1021/jp044928f",
language = "English",
volume = "109",
pages = "3793--3799",
journal = "Journal of Physical Chemistry B Materials",
issn = "1520-6106",
publisher = "American Chemical Society",
number = "9",

}

TY - JOUR

T1 - (CdSe)ZnS quantum dots and organophosphorus hydrolase bioconjugate as biosensors for detection of paraoxon

AU - Ji, Xiaojun

AU - Zheng, Jiayin

AU - Xu, Jianmin

AU - Rastogi, Vipin K.

AU - Cheng, Tu Chen

AU - DeFrank, Joseph J.

AU - Leblanc, Roger

PY - 2005/3/10

Y1 - 2005/3/10

N2 - In this paper, we first report a novel biosensor for the detection of paraoxon based on (CdSe)ZnS core - shell quantum dots (QDs) and an organophosphorus hydrolase (OPH) bioconjugate. The OPH was coupled to (CdSe)ZnS core - shell QDs through electrostatic interaction between negatively charged QDs surfaces and the positively charged protein side chain and ending groups ( - NH 2). Circular dichroism (CD) spectroscopy showed no significant change in the secondary structure of OPH after the bioconjugation, which indicates that the activity of OPH was preserved. Detectable secondary structure changes were observed by CD spectroscopy when the OPH/QDs bioconjugate was exposed to organophosphorus compounds such as paraoxon. Photoluminescence (PL) spectroscopic study showed that the PL intensity of the OPH/QDs bioconjugate was quenched in the presence of paraoxon. The overall quenching percentage as a function of paraoxon concentration matched very well with the Michaelis - Menten equation. This result indicated that the quenching of PL intensity was caused by the conformational change in the enzyme, which is confirmed by CD measurements. The detection limit of paraoxon concentration using OPH/QDs bioconjugate was about 10 -8 M. Although increasing the OPH molar ratio in the bioconjugates will slightly increase the sensitivity of biosensor, no further increase of sensitivity was achieved when the molar ratio of OPH to QDs was greater than 20 because the surface of QDs was saturated by OPH. These properties make the OPH/QDs bioconjugate a promising biosensor for the detection of organophosphorus compounds.

AB - In this paper, we first report a novel biosensor for the detection of paraoxon based on (CdSe)ZnS core - shell quantum dots (QDs) and an organophosphorus hydrolase (OPH) bioconjugate. The OPH was coupled to (CdSe)ZnS core - shell QDs through electrostatic interaction between negatively charged QDs surfaces and the positively charged protein side chain and ending groups ( - NH 2). Circular dichroism (CD) spectroscopy showed no significant change in the secondary structure of OPH after the bioconjugation, which indicates that the activity of OPH was preserved. Detectable secondary structure changes were observed by CD spectroscopy when the OPH/QDs bioconjugate was exposed to organophosphorus compounds such as paraoxon. Photoluminescence (PL) spectroscopic study showed that the PL intensity of the OPH/QDs bioconjugate was quenched in the presence of paraoxon. The overall quenching percentage as a function of paraoxon concentration matched very well with the Michaelis - Menten equation. This result indicated that the quenching of PL intensity was caused by the conformational change in the enzyme, which is confirmed by CD measurements. The detection limit of paraoxon concentration using OPH/QDs bioconjugate was about 10 -8 M. Although increasing the OPH molar ratio in the bioconjugates will slightly increase the sensitivity of biosensor, no further increase of sensitivity was achieved when the molar ratio of OPH to QDs was greater than 20 because the surface of QDs was saturated by OPH. These properties make the OPH/QDs bioconjugate a promising biosensor for the detection of organophosphorus compounds.

UR - http://www.scopus.com/inward/record.url?scp=15544370095&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=15544370095&partnerID=8YFLogxK

U2 - 10.1021/jp044928f

DO - 10.1021/jp044928f

M3 - Article

C2 - 16851427

AN - SCOPUS:15544370095

VL - 109

SP - 3793

EP - 3799

JO - Journal of Physical Chemistry B Materials

JF - Journal of Physical Chemistry B Materials

SN - 1520-6106

IS - 9

ER -