Indirect Competitive Assays on DVD for Direct Multiplex Detection of
Drugs of Abuse in Oral Fluids
Lingling Zhang,
†,‡
Xiaochun Li,
‡
Yunchao Li,*
,†
Xiaoli Shi,
†
and Hua-Zhong Yu*
,‡,§
†
Department of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
‡
Key Laboratory of Advanced Transducers and Intelligent Control Systems (Shanxi Province and Ministry of Education), Taiyuan
University of Technology, Shanxi 030024, P. R. China
§
Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
*
S
Supporting Information
ABSTRACT: On-site oral fluid testing for drugs of abuse has
become prominent in order to take immediate administrative
action in an enforcement process. Herein, we report a DVD
technology-based indirect competitive immunoassay platform
for the quantitative detection of drugs of abuse. A microfluidic
approach was adapted to prepare multiplex immunoassays on a
standard DVD-R, an unmodified multimode DVD/Blu-Ray
drive to read signal, and a free disc-quality analysis software
program to process the data. The DVD assay platform was
successfully demonstrated for the simultaneous, quantitative
detection of drug candidates (morphine and cocaine) in oral
fluids with high selectivity. The detection limit achieved was as
low as 1.0 ppb for morphine and 5.0 ppb for cocaine,
comparable with that of standard mass spectrometry and ELISA methods.
A
s popular psychoactive drugs, morphine and cocaine have
been widely abused in many cases for the purpose of
reducing pain, self-regulating emotion or enhancing athletic
performance,
1,2
which significantly distort the minds, behaviors
and body conditions of the abuser and cause serious
consequences. Rapid on-site detection of these drugs and
their metabolites in human body fluids (such as blood, urine,
and oral fluids) is one of the most straightforward ways to
ascertain their illicit uses (especially for sport competition,
driving, and criminal justice). Up to date, the established
methods for detecting these drugs in human body fluids have
included gas chromatography/mass spectrometry (GC/MS),
3
liquid chromatography/mass spectrometry (LC/MS),
4−8
and
enzyme-linked immunosorbent assay (ELISA).
9−11
Electro-
chemical biosensors
12−14
and point-of-collection testing
(POCT) devices
15,16
are relatively new additions. Among
these dete ction methods, conventional mass spectrometry
(MS) method is still the gold standard for the detection of
drugs of abuse because of its high accuracy and sensitivity.
3−6
However, the MS techniques typically involve complicate
operation and require sophisticate instrumentation; thus their
application is limited to well-equipped, centralized laboratories
or hospitals. ELISA kits and electrochemical biosensors are
relatively simple and easy to use, but they still rely on special
equipment for signal readout and data processing. Point-of-
collection testing (POCT) devices, which were designed for
on-site detection of drugs of abuse in oral fluids,
15,16
allow the
sample collection and analysis to be performed easily and
quickly. The Substance Abuse and Mental Health Services
Administration (SAMHSA) proposed these devices for drug
testing in oral fluids.
17
It should be pointed out that the current
commercial POCT devices have a limited detection sensitivity
and throughput and only provide qualitative results, which do
not fully meet the practical needs for accurate on-site analysis.
Recently, compact disc (CD) and digital versatile disc
(DVD) systems have been adapted as inexpensive, portable and
high-throughput analytical platforms for detecting various
targets,
18−26
indicating their potential in solving the on-site
drug analysis challenge. In this paper, we report a DVD
technology-based immunoassay platform fo r the direct
detection of morphine and cocaine individually or simulta-
neously. To create such a platform, the drug recognition
reactions were performed in an indirect competitive format at
specific locations on regular DVD discs; the reactions were
amplified by a silver-staining protocol and the assay signal read
by a conventional DVD/Blu-ray drive (represented as digital
reading errors). This DVD assay platform was examined for the
detection of two representative drug candidates (morphine and
cocaine) in oral and blood fluids. We show that this DVD-
based immunoassay platform promises a powerful on-site
analytical tool for ascertaining the illicit uses of drugs in various
fields.
Received: November 1, 2014
Accepted: December 23, 2014
Published: December 23, 2014
Article
pubs.acs.org/ac
© 2014 American Chemical Society 1896 DOI: 10.1021/ac5040715
Anal. Chem. 2015, 87, 1896− 1902