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REVIEW
Copyright © 2011 American Scientific Publishers
All rights reserved
Printed in the United States of America
Journal of
Biomedical Nanotechnology
Vol. 7, 1–9, 2011
Gold Nanoparticle Based Microbial
Detection and Identification
Muhammad Ali Syed and S. Habib Ali Bukhari∗
Department of Biosciences, Comsats Institute of Information Technology, Islamabad, Pakistan
Microorganisms belong to one of the biggest threats to humanity. Rapid detection and identification
of microbes in environmental, food and clinical samples is required for safety purposes as well as
diagnosis of infectious diseases. Conventional techniques for microbial detection, though reliable
and gold standard, are time consuming, expensive and unsuitable for field situations. Advent of
novel techniques involving Nanotechnology has been promising for the development of rapid and
low cost strategies for rapid detection and identification of microbes with higher sensitivity. Gold
nanoparticles find a significant place in medicine, material sciences as well as diagnostics for their
unique optical and physiochemical properties. This review focuses at recent advancements in the
development of gold nanoparticle based assays for microbial detection and identification.
Keywords: Microorganisms, Gold Nanoparticles, Immuno PCR, Immunochromatographic Strips,
SERS etc.
CONTENTS
1. Introduction ................................. 1
2. Microbiology Meets Nanotechnology ................. 2
2.1. Unique Features of Gold Nanoparticles ............ 2
2.2. Gold Nanoparticle Based Identification of Microbes .... 3
2.3. Immunochromatographic Strips for Microbial
Detection and Identification .................... 3
2.4. Gold Nanoparticle Based Assays for
Microbial DNA Detection ..................... 3
2.5. Bio Barcode Based Assays for Microbial
DNA Detection ........................... 4
3. Gold Nanoparticles in Immuno PCR ................. 4
3.1. Gold Nanoparticles in Biosensors for
Microbial Detection ......................... 5
3.2. Gold Nanoparticle Based Nanosensors ............. 6
4. Conclusion ................................. 7
Acknowledgment ............................. 7
References and Notes ........................... 7
1. INTRODUCTION
The world of microbes is extremely diverse and human
efforts are aimed at on one hand to prevent mankind from
dangers of microbial attacks and on the other hand benefit-
ing from their useful aspects. Microbes have been endan-
gering human species, which is evident from the great
outbreaks in the history and our current battle against
most horrifying diseases such as AIDS, tuberculosis, swine
flu and SARS. Microbial diseases are significant problem
∗Author to whom correspondence should be addressed.
for both developing and developed countries.1–5 Microbial
detection and identification is the first and key step to pre-
vent us from them or benefit for our wellbeing.5Moreover,
highly sensitive detection of microbes and their toxins is
important in cases where very small number of bacterial
cells of their product can cause disease.6
Microbial identification is usually carried out using
classic techniques such as microscopy, growing them on
selective or differential media, performing biochemical or
serological tests or using more sophisticated molecular
biological techniques such as PCR, nucleic acid probe
hybridization, gene sequencing etc.578The classic tech-
niques of microbial identification, though reliable, are time
consuming and laborious, whereas modern molecular bio-
logical techniques are expensive and unsuitable for field
situations.59–12 Therefore, new field deployable diagnos-
tic modalities are required for the early and point of
care applications.11–13 Nanotechnology based techniques
promise unprecedented advantage of rapid, sensitive, spe-
cific and cost effective detection of microbes with wide
range of applications in diagnostics, Biomedicine, Agricul-
ture, Environmental monitoring and Biotechnology.4513–14
Gold nanoparticles find a significant position among all
Nanotechnology based assays for microbial detection.1015
This review is aimed at providing the basic understanding
of the use of gold nanoparticles in microbial detection and
identification with examples of recent developments in this
area.
J. Biomed. Nanotechnol. 2011, Vol. 7, No. 2 1550-7033/2011/7/001/009 doi:10.1166/jbn.2011.1281 1
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Development of Rapid Diagnostic Methodologies for Microbial Detection Syed and Bukhari
2. MICROBIOLOGY MEETS
NANOTECHNOLOGY
Nanotechnology deals with the creation and utilization of
materials at nanometer scale.16 Like many other branches
of physical and biological sciences Nanotechnology has
also revolutionized the field of Microbiology by offer-
ing fast, cost effective and reliable techniques of micro-
bial identification. Properties possessed by the material at
nanoscale are different than that of bulk due to their small
size, larger surface to volume ratio, enhanced surface reac-
tivity, quantum confinement, magnetic and conductance
properties among others.5One of the areas of applications
of Nanotechnology is pathogen detection in food, water
and clinical or environmental samples. In the past decade
a lot of research demonstrating high level of synergism
between Microbiology, Nanotechnology and Microelec-
tromechanical systems (MEMS) directed towards devel-
oping rapid diagnostic techniques have been observed.10
These technologies offer opportunity to monitor the cellu-
lar processes even at single cell level. Quantum dots and
gold and magnetic nanoparticles may find great application
in diagnostics. Label free detection of microbes and their
metabolites is a remarkable advantage offered by these
novel and highly sensitive techniques.17–18
2.1. Unique Features of Gold Nanoparticles
Gold nanoparticles are at the leading edge of very rapidly
progressing field of Nanomedicine.19 Reliable, repro-
ducible and high yielding methods for Gold nanoparticle
synthesis has been developed over the last half century.20
Muhammad Ali Syed is a Ph.D. candidate in Biosciences at Comsats Institute of Infor-
mation Technology Islamabad. He achieved his M.Sc. degree in Biomedical Sciences from
Kingston University UK. In his undergraduation, he studied Chemistry at University of Wup-
pertal Germany. His current research interests include nanoparticle based microbial detection
systems, single molecule and cell imaging by scanning probe microscopy and SPR based
biosensors.
Dr. Habib Ali Bokhari is Assistant Professor in Biosciences at department of Biosciences
of Comsats Institute of Information Technology Islamabad. He obtained his Ph.D. degree in
Microbiology from University of Glasgow UK. Dr. Bokhari has been awarded with post doc.
positions at George Mason University USA and London School of Hygiene and Tropical
Medicine. He has won a number of research grants from local and international organiza-
tions. His areas of interest include Bioinformatics, vaccine efficacy, molecular epidemiology
of infectious diseases and Nanotechnology based systems for control and identification of
microbes.
The unique size dependent physiochemical properties pos-
sessed by gold nanoparticles make them an ideal mate-
rial to be used in the detection of biomolecules at lowest
concentration.21 One of their characteristic features is the
Surface Plasmon Resonance (SPR) phenomenon, which is
responsible for their larger absorption and scattering cross
sections. Furthermore, the optical properties of the gold
nanoparticles can be controlled by varying their size, shape
and composition. Gold nanoparticles are easier to function-
alize with biomolecules such as antibodies, nucleic acid
probes, glycoproteins etc.21–23
Materials developed at the nanoscale may also pose
risk to human health and environment. Many types of the
nanoparticles (e.g., Ag, ZnO, Co etc.) have been found
to be toxic to humans as well as microbes which restrict
their in vivo application in humans as well as targeting
microorganisms.24–26 Therefore, the class of nanoparticles
that may find its application in medicine and diagnostics
needs to be non-toxic and biocompatible. Although there
are some reports of toxicity of gold nanoparticles, they are
so far considered safe for their in vivo applications.28–29
Composite nanoparticles are gaining increasing applica-
tion in life sciences and medicine. An example of these
materials is superparamagnetic gold nanoshells. The core
of these shells is composed of magnetic material such as
Iron oxide, whereas the shell part is gold. Therefore mag-
netic nanonoshells possess the features of both magnetic
and gold nanoparticles, which are gaining broader range
of applications in diagnostics, therapeutics, imaging and
biosensing.30–31
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Syed and Bukhari Development of Rapid Diagnostic Methodologies for Microbial Detection
Fig. 1. AuNP conjugated with single stranded DNA (ssDNA).
2.2. Gold Nanoparticle Based
Identification of Microbes
The size dependent optical properties of the gold nanopar-
ticles have been exploited to use them in the diagnostics
to detect pathogens, their products, and antibodies pro-
duced in response to their presence.32 Gold nanoparticles
may be functionalized with antibodies or some other lig-
and to target the pathogen of interest. Furthermore, nucleic
acid sequences complementary to microbial DNA or RNA
may be attached to the gold nanoparticles to monitor the
microbial presence. The thiol modified ssDNA may be
used as tags which bind with the complementary micro-
bial sequences (Fig. 1). Aggregation of nanoparticles due
to binding with the complementary sequences brings about
the color change.33–34 Moreover, gold nanoparticles based
assays should also be working well in the presence of very
small analyte.35
2.3. Immunochromatographic Strips for Microbial
Detection and Identification
An elegant example of gold nanoparticle based assays
for microbial detection and identification are immunochro-
matographic strips.36 These assays are based on membrane
chromatography and utilize colloidal gold nanoparticles
conjugated with the antibodies as a tracer.37 These strips
offer advantage of rapid, efficient, cost effective and simple
way of microbial detection requiring minimum equipments
and expertise (Fig. 2). Dip stick tests are getting popular
and there have been a large number of reports on the devel-
opment and successful utility of them. These assays are
based on the capture of the microbial cells or their products
by the immobilized antibodies and development of a red
colored line in the detection zone of the strip. Moreover,
strips have been developed for the detection of antibodies
Fig. 2. Immunochromatographic strip biosensor. Appearance of the test
line indicates positive test due to the presence of antigen, whereas control
line appears in both positive and negative results. Absorption pad absorbs
the excessive sample.
developed in response to some infection. In that case strips
utilize the immobilization of inactivated microbial antigens
to capture the antibodies.38 A typical immunochromato-
graphic strip is composed of four elements, an absorbent
paper (cellulose fiber), conjugate pad (glass fiber mem-
brane), analytical membrane (nitrocellulose) and absorbent
pad (cellulose).37 The liquid sample is applied to the sample
pad which rapidly moves to the conjugation pad. If there
is any antigen in the sample it will react with the antibody
conjugated gold nanoparticles here. A second antibody to
the same antigen is immobilized on the nitrocellulose pad,
which captures the antigen-gold nanoparticle-antibody con-
jugate complex and produces characteristic red color due
to the aggregation of colloidal gold nanoparticles.38 A con-
trol line on the nitrocellulose pad contains secondary anti-
bodies against the two antibodies used in the test giving
red color upon binding to the antibodies used in the test.
The conjugate finally moves to the absorbent pad where it
is retained.38–39 Immunochromatographic strips have been
developed against a number of viral, bacterial, fungal and
protozoan species36–39 and some of them are now commer-
cially available.40
Development of these assays is usually hampered by
unavailability of adequate antibodies which are very
expensive and usually difficult to produce against a
number of toxic biologicals such many potent toxins.41
Another class of biomolecules that rivals antibodies, called
aptamers, may be used instead. The unusual molecular
recognition properties of the aptamers may be combined
with the unique optical properties of gold nanoparticles
to develop dry reagent strip biosensor for the analysis of
proteins and microbes.42–43
2.4. Gold Nanoparticle Based Assays for Microbial
DNA Detection
There have been increased efforts to develop rapid, real
time, and inexpensive assays for DNA sequence, sin-
gle nucleotide polymorphism (SNP) detections and gene
expression analysis. Microbes are extremely difficult to
detect and identify in situations when they are slow grow-
ing, small in number or produce insignificant amount
of antibodies to make early diagnosis. Many diagnos-
tic assays are aimed at detecting specific nucleic acid
sequences from the sample using molecular techniques
J. Biomed. Nanotechnol. 7, 1–9, 2011 3
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Development of Rapid Diagnostic Methodologies for Microbial Detection Syed and Bukhari
such as PCR, which is expensive and time consuming.
A number of attempts have been made to detect viral
and bacterial genomic DNA using gold nanoparticles.43
Mirkin et al. were the fist to use gold nanoparticles to label
with DNA.35 A number of efforts have been made since
their initial report on the aggregation of DNA functional-
ized gold nanoparticle. Binding of single stranded DNA
probe with the colloidal gold nanoparticles is achieved
by the addition of thiol (–SH) group to one end of the
DNA probe, which has strong affinity to gold (Fig. 1).
In a microarray based strategy for DNA detection specific
DNA probes are immobilized on the glass slide which
are then exposed to the complementary sequence of the
microbial DNA. Gold nanoparticles functionalized with
DNA probes are used to detect the DNA binding on the
micro array chip. Optical detection methods such as colori-
metric and surface enhanced ramen spectroscopy (SERS)
may be used to detect the binding of derivatized gold
nanoparticle.43–44 In a recent publication Liandris et al.
have designed and reported gold nanoparticle based assays
for mycobacterial DNA detection. As tuberculosis is a
leading case of morbidity and mortality in both devel-
oping and developed countries, its diagnosis is hampered
by slow growth of mycobacteria and latency of infec-
tion. The laboratory diagnosis of mybobacteria is based on
the bacterial detection through Ziehl Neelson microscopy,
ELISA, culture and PCR; each of these methods has both
advantages and limitations. Liandris et al. have developed
universal probes for Mycobacterium tuberculosis com-
plex (MTC), Mycobacterium avium complex (MAC) and
Mycobacterium avium subsp. paratuberculosis (MAP) to
be used in gold nanoparticles based mycobacterial DNA
detection. They functionalized the gold nanoparticles with
these probes which appeared pink. Addition of HCl to
the probe functionalized gold nanoparticles brought about
color change to purple due to aggregation of nanoparticles.
In contrast, binding of these probes with complementary
sequences in the mycobacterial genomic DNA produced
no color change upon addition of HCl. This way they
could detect 18.75 ng of mycobacterial DNA.34
Gold nanoparticle based assays have also been
employed for viral DNA/RNA detection, combining the
advantage of signal amplification of biosensors to give
rapid, accurate and label free viral detection. As gold
nanoparticles have also been used for signal amplification
in some types of biosensors, their used has advanced from
direct detection to the signal enhancement. Uludag and
coworkers developed mass sensitive acoustic wave biosen-
sor for Herpes Simplex 1 virus (HSV-1). They used DNA
probe conjugated gold nanoparticles to hybridize with the
target DNA at the sensor surface.45
2.5. Bio Barcode Based Assays for
Microbial DNA Detection
Biobarcode amplification (BBA) technology is a promis-
ing method of enzyme free detection of microbial DNA
with sensitivity comparable to PCR. It is thought that this
new technology is going to replace the PCR. BBA offers
unique opportunity for multiplex microbial DNA detection
with higher sensitivity and specificity.46–47 This technique
uses two types of nanoparticle i.e., gold nanoparticles for
signal amplification and magnetic nanoparticles for sep-
aration of nucleic acid sequences.46 The gold nanopar-
ticles possess two probes attached, one for the target
sequence and the other is the barcode identifier sequence.
Magnetic microparticles have complementary sequence to
some other part of the target nucleic acid sequence. These
two particles sandwich the target sequence in the sam-
ple. Once the sandwich structure is formed, magnetic field
is applied to collect them. Excess sample is removed
by washing and the barcode strands are removed using
dithiotreitol (DTT). These barcode strands are identified
using micro array chip.46–47
Although barcode based assays have been described
recently,46 there have been a number of publications on
the successful utilization of it for detection of DNA from
a number of species including many microbial. Zhang
et al. developed a barcode based assay for the detec-
tion of Salmonella enterica serovar. Enteritidis targeting
lel insertion sequence in the DNA.49 Tang et al. modi-
fied the barcode amplification assay for the detection of
Human Immunodeficiency Type 1 capsid antigen (p24)
which acts as a surrogate marker for HIV infection. In their
work monoclonal antibodies were immobilized on walls
of microtitre plates that captures the viral particles in the
sample. A second biotinylated antibody to the viral anti-
gen was used to sandwich the virions. Streptavidin coated
Au-NPs with barcode DNA recognized the biotinylated
antibody on the virion. The Barcode DNA was eluted by
heating and identified through scannometric detection on
the complementary probes hybridized on the glass slide.
This modified BBA was about 150 fold more sensitive that
the conventional ELISA based detection.50
3. GOLD NANOPARTICLES IN
IMMUNO PCR (IPCR)
PCR offers exponential amplification of microbial nucleic
acids which makes it a highly sensitive technique. How-
ever, many situations demand detection of antigens or anti-
bodies whose number or sequences can not be amplified.
IPCR, originally introduced by Sano et al. (2002) is a
highly sensitive technique that combines both immunol-
ogy and PCR to detect proteins of interest.51 Antibodies
conjugated with the known DNA sequence are used to
target the antigen of interest in the sample followed by
PCR amplification of this sequence (Fig. 4). Alternatively,
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Syed and Bukhari Development of Rapid Diagnostic Methodologies for Microbial Detection
Fig. 3. Biobarcode assay format for the detection of antigen of interest.
1. Magnetic microparticle (MMP) is conjugated with the antibody to the
antigen of interest. 2. Gold nanoparticle (Au-NP) conjugated with the
antibody to the antigen as well as barcode DNA sequences. Antigen is
sandwiched between Au-NP and MMP. Magnetic field is applied to sepa-
rate this complex. 3. PCR amplification and identification of the barcode
sequence.
antibodies are used to target the antigen and a secondary
antibody combined with the known DNA sequence is used
to bind the first antibody. Amplification of the DNA probe
bound to the secondary antibodies determines the amount
of antigen quantitatively. The detection limit of a typical
ELISA is generally enhanced to 100–10,000 fold using
IPCR.52–57 IPCR has extended from its use in the research
to the diagnostic laboratories for detection of proteins with
higher sensitivity. A number of attempts have been made
to enhance the efficacy and sensitivity of IPCR namely
use of phage display technology and combining IPCR with
BBA.55
Gold nanoparticles, like their applications in other tech-
niques, have also been used for sensitivity enhancement
of IPCR. A number of papers reported the combination of
gold nanoparticles for sensitivity enhancement of IPCR.
Conjugation of antibodies with gold nanoparticles is easier
as compared to direct conjugation with the DNA. Further-
more, more molecules of DNA can be attached to gold
Fig. 4. Immuno PCR for the detection of the antigen of interest. DNA
conjugated antibody is used to detect the antigen. PCR amplification of
the DNA sequence determines the presence of the antigen quantitatively.
nanoparticles, which will further increase the sensitivity of
the IPCR. Chen et al. used the similar strategy and com-
bined the IPCR with the BBA and called the new assay
setup as gold nanoparticle enhanced Immuno PCR for the
detection of Hantaan virus nucleocapsid protein. They uti-
lized polyclonal antibodies coated microtitre ELISA plate
and the gold nanoparticles bearing barcode DNA and mon-
oclonal antibody to Hantaan virus nucleocapsid. The signal
sequence was released by heating and amplified using real
time PCR.51
3.1. Gold Nanoparticles in Biosensors for
Microbial Detection
Research in biosensors has experienced an explosive
growth over the last decade. A biosensor may be defined
as a device that converts a biological response into a quan-
tifiable and processable electronic signal. Biosensors are
further divided into different types on the basis of trans-
ducer such as optical, resonant, electrochemical, thermal
detection and Ion sensitive FET biosensors.55
Electrochemical biosensors offer an attractive means of
analysis of content of biological sample due to their abil-
ity to convert biological event into an electronic signal.
Over the years an enormous number of efforts have been
made to develop electrochemical biosensors for the detec-
tions of microbes from food, clinical and environmental
samples as well as biowarfare agents.58 Electrochemical
biosensors are among the most commonly used and sen-
sitive types of biosensors used nowadays.58–59 One of the
most common application of these biosensors is the moni-
toring the presence of pathogenic microorganisms for food
and environmental safety. As there is an increasing threat
of bioterrorism, biosensors serve as promising tools for
the detection of biological warfare agents.58 Electroche-
mical biosensors have been developed which rely on the
microbial physiology, ligand receptor interaction or pres-
ence of nucleic acid sequences. Electrochemical biosensors
may be further divided into conductometric, amperomet-
ric and potentiometer biosensors, depending upon the
type of electrochemical property being measured.60–61 The
ability of colloidal gold nanoparticles to immobilize the
biomolecules retaining their biological activity is of high
significance in the development of a biosensor. Further-
more, gold nanoparticles mediate direct electron transfer
between redox proteins and bulk electrode materials allow-
ing electron transduction without any need of mediators.62
The sensitivity of an electrochemical biosensor depends
upon the binding of recognition element such DNA on the
transducer surface. There have been several approaches to
attach the ssDNA namely physical adsorption, using cross
linker, entrapment in the gel or covalent binding. As men-
tioned earlier, gold nanoparticles have been used for signal
enhancement in biosensors due to their larger surface to
volume ratio. Immobilization of gold nanoparticles conju-
gated with the ssDNA onto the electrode surface has shown
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Development of Rapid Diagnostic Methodologies for Microbial Detection Syed and Bukhari
increased sensitivity in the electrochemical biosensors.63
Gold nanoparticles have also been used as signal ampli-
fiers in quartz crystal microbalance (QCM) and SPR based
biosensors for microbial detection.64
Immunosensors based on SPR provide a rapid and
efficient alternative to conventional microbiological tech-
niques for microbial detection. Immunosensors utilize the
specific antibody as a probe, which is raised against the
analyte (i.e., bacteria, virus, toxin etc.). SPR is the collec-
tive oscillation of electrons that develops along the inter-
face between metal and an adjacent dielectric. For a metal
thin film, the light above the critical angle is ordinarily
completely reflected. However, light is absorbed at certain
angle, polarization, and wave length, reducing the intensity
of the reflected light to lower value.65 Capture of analyte
at the sensors surface is indicated by change in the SPR
dip position. SPR based Immunosensors offer the advan-
tage of label free, real time and cost effective means of
microbial detection from clinical, environmental, food and
water samples.66 SPR based Immunosensors have been
developed for the detection of bacteria, fungi, viruses and
microbial toxins and over the years automated SPR equip-
ments have arrived in the market with the ability of kinetic
analysis of biomolecular interaction.6566–69 Unique opti-
cal features of gold nanoparticles have been exploited for
the sensitivity enhancement of SPR based immunosensors
in many reports, which is not only due to their mass but
also the signal enhancing potential of SPR phenomena.
Gold nanoparticles have successfully been used in the sig-
nal enhancement for a number of biomolecules as wells
as bacteria.69–70 Bioconjugation of gold nanoparticles with
monoclonal antibodies can take place by means of phy-
sical adsorptions, covalent bonding or using some adapter
molecules.71 Once analytes has been captured by the mon-
oclonal antibody at the gold sensor surface, Au-NP anti-
body conjugate can be applied to enhance the signal and
hence detection limit.
3.2. Gold Nanoparticle Based Nanosensors
Nanosensors are the sensors with dimension at nanoscale.
As we have already discussed that the physiochemical
properties of materials change at nanometer scale due to
higher surface to volume ratio resulting in the predom-
inance of the surface phenomena over the physics and
chemistry in bulk.72 The capability of studying biomolecu-
lar interactions of a single cell using advanced and sophis-
ticated techniques of Nanotechnology will greatly enhance
our understanding of cellular function, therefore, revolu-
tionizing the sciences of Cell and Microbiology. As Micro-
biology is nowadays much focused at the single cell or
so called Quantal Microbiology, these nanosensors utiliz-
ing the nanoparticles, particularly gold, will facilitate the
development of arrays to study the cellular processes at a
single cell level in the bulk.7374
Raman spectroscopy has long been a reliable method
for specific identification of molecules. Since its discov-
ery in 1970s, SERS have been applied in a number
of analytical applications including Chemistry and Life
Sciences.75 In simple words, Ramen Spectroscopy involves
shining the laser light source on the molecules. Most of
the absorbed light will be scattered back at the same
wavelength. However, small proportion will be scattered
at series of wavelengths that is indicative of vibration
transition of that molecule. The technique had limited
applicability due to limited efficiency of the inelastically
scattering process. SERS was introduced to tackle this
issue about 30 years ago. In SERS target molecule is
brought in close proximity of metallic surface of (e.g., Au,
Ag, and Cu) with nanoscopically defined features with a
size smaller than the wavelength of light. When the light
is incident on the surface of the particle a surface plas-
mon mode is excited, which enhances the electromagnetic
energy in vincity of the target molecule, therefore enhanc-
ing the intensity of the inelastically scattered light.76–77
SERS provides detailed structural information on biologi-
cal molecules such as proteins, nucleic acids or even whole
pathogens. Raman spectrophotometry has been used for
the detection of pathogens such as viruses and bacteria.75
It has long been thought that unique vibrational spectra
of pathogens will be used for their identification. Raman
spectroscopy has successfully been used to identify the
pathogens due to their inherent spectral differences or fin-
ger prints. Both intrinsic and extrinsic formats of SERS
have been used for the finger printing of bacteria, viruses
and protein molecules.76 SERS offers enormous advan-
tages over other techniques of microbial and biomole-
cular identification and does not require amplification of
nucleic acid sequence. Therefore, SERS based identifica-
tion of microbes is achieved in minimum period of time
by less trained personnel.78–79 Shanmukh et al. used SERS
based strategy to classify Respiratory Synctial Virus (RSV)
strains. The four viral strains were detected and classified
on the basis of SERS spectra.80 In a recent study Cheng
et al. reported the development of SERS based assay for
the detection of dipicolinic acid, a biomarker for bacte-
rial spores including pathogenic bacterial species such as
Bacillus anthracis, using Au-NP/PVP/Au substrate.81
Fluorescence Energy Transfer (FRET) has been a
useful tool in fluorescence based biosensors measuring
extremely small proximity changes between the fluores-
cent molecules. Stringer et al. have proposed a novel
method of Pocrine Reproductive and Respiratory Syn-
drome Virus (PRRSV) detection utilizing nanophotonic
and optical biosensor technology. In this strategy fluo-
rescently labeled antibodies to PRRSV were attached to
protein A, which is labeled with Au-NP. Exposure to
PRRSV causes binding event between the antibody and the
viral antigen resulting in the conformational change within
biosensor complex. The conformational change increases
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Syed and Bukhari Development of Rapid Diagnostic Methodologies for Microbial Detection
distance between the fluorescent molecules leading to a
change in the fluorescent spectra due to the non radioactive
signal transduction method (FRET) between the fluores-
cent dye and the Au-NP. This system detected PRRSV in
solution with a detection limit of 3 particles/l.82
4. CONCLUSION
Much of the research in Nanomedicine is focused at the
application of gold nanoparticles in imaging, diagnostics
and therapeutics. The need for advent of novel detection
techniques for microbes continues to combat the global
problems of infectious disease in general and possible
bioterrorism attacks in particular. There have been signifi-
cant advancements in the field of microbial detection and
identification exploiting unique features of gold nanopar-
ticles in the last decade. However, most of the work
being carried out in this arena is in the initial stage of
development and further simplification and commercial-
ization of the assays are likely to be achieved very soon
as the sciences of Nanotechnology moves from infancy.
Immunochromatographic strips for bacterial detection are
already commercially available and other applications are
largely being used in research for signal amplification pur-
poses. In any case, commercialization of biosensors seems
to be coupled with utilization of gold nanoparticles as a
signal enhancement agent.
Acknowledgment: Authors are highly grateful to
Department of Biosciences of Comsats Institute of Infor-
mation Technology Islamabad-Pakistan for their coopera-
tion and encouragement for this work.
References and Notes
1. A. K. M. Zaidi, S. Awasthi, and H. J. DeSilva, Burden of infectious
diseases in South Asia. Brit Med. J. 328 (2004).
2. O. Lazcka, F. J. Del Campo, and F. X. Munoz, Pathogen detection:
A perspective of traditional methods and biosensors. Biosens. Bio-
electron. 22, 1205 (2007).
3. D. A. Relman, Shedding light on microbial detection. N. Engl. J.
Med. 349, 2162.
4. L. A. Metherell, C. Hurst, and I. J. Brure, Rapid, sensitive, microbial
detection by gene amplification using restriction endonuclease target
sequences. Mol. Cell Probes. 11, 297 (1997).
5. C. Kaittanis, S. Santimukul, and J. M. Perez, Emerging
nanotechnology-based strategies for the identification of microbial
pathogenesis. Adv. Drug. Deliv. Rev. 31, 137 (2009).
6. D. V. Lim, Detection of microorganisms and toxins with evanes-
cent wave fiber—Optic biosensors, Proceedings of the IEEE. 91, 902
(2003).
7. S. Nakamura, N. Maeda, I. M. Miron, M. Yoh, K. Izutsu, C. Kataoka,
T. Honda, T. Yasunaga, T. Nakaya, J. Kawai, Y. Hyashizaki, T. Horii,
and T. Lida, Metagenomic diagnosis of bacterial infections. Emerg.
Infect. Dis. 14, 1784 (2008).
8. K. L. Josephson, C. P. Gerba, and I. L. Pepper, Polymerase chain
reaction detection of nonviable bacterial pathogens. Appl. Environ.
Microbiol. 59, 3513 (1993).
9. I. Vliegen, J. A. Jacobs, E. Beuken A. Cathrien, and B. C.
Vink, Rapid identification of bacteria by real-time amplification and
sequencing of the 16S rRNA gene. J. Micobiol. Meths. 66, 156
(2006).
10. C. Kaittanis, S. Santra, and J. M. Perez, Emerging nanotechnology-
based strategies for the identification of microbial pathogenesis. Adv.
Drug. Deliv. Rev. 62, 408 (2010).
11. D. Ivnitski, I. Abdel-Hamid, P. Atanasov, and E. Wilkins, Biosensors
for detection of pathogenic bacteria. Biosens. Bioelectron. 44, 599
(1999).
12. B. K. Oh, W. Lee, B. S. Chun, Y. M. Bae, W. H. Lee, and J. W. Choi,
The fabrication of protein chip based on surface plasmon resonance
for detection of pathogens. Biosens. Bioelectron. 20, 1847 (2005).
13. J. W. Choi and B. K. Oh, Optical detection of pathogens using pro-
tein chip, edited by Y. J. Kim and U. Platt, Advanced Environmental
Monitoring, Springer (2008), pp. 348–362.
14. F. C. Dudak and I. K. Boyaci, Development of an immunosen-
sor based on surface plasmon resonance (SPR) for enumeration of
E. coli in water samples. Food Res. Int. 40, 804 (2007).
15. Y. Li, H. J. Schluesener, and S. Xu, Gold nanoparticle based biosen-
sors. Gold Bull. 43, 29 (2010).
16. L. A. Dykman and V. A. Bogatyrev, Gold nanoparticles: Preparation,
functionalisation and applications in biochemistry and immunochem-
istry. Russ. Chem. Rev. 76, 181 (2007).
17. K. K. Jain, Nanotechnology in clinical laboratory diagnostics. Clin.
Chim. Acta. 358, 37 (2005).
18. S. Bhattacharia, J. Jang, L, Yang, D. Akin, and R. Bashir, Biomems
and nanotechnology based approaches for rapid detection of biolo-
gical entities. J. Rapid. Meth. Aut. Mic. 15, 1 (2007).
19. O. V. Salata, Application of nanoparticles in Biology and Medicine.
J. Nanobiotechnol. 2,1(2004).
20. D. A. Giljohann, D. S. Sefereos, W. L. Daniel, M. D. Masich,
P. C. Patel, and C. A. Mirkin, Gold nanoparticles for biology and
medicine. Angew. Chem. Int. Edit. 49, 3280 (2010).
21. R. Wilson, The use of gold nanoparticles in diagnostics and detec-
tion. Chem. Soc. Rev. 2028 (2008).
22. S. H. Razwan and H. M. Azazzy, Gold nanoparticles for molecular
diagnostics. Expert. Rev. Mol. Diagn. 9, 511 (2009).
23. Q. Huo and J. G. Worden, Monofunctional gold nanoparticles: Syn-
thesis and applications. J. Nanopart. Res. 9, 1013 (2007).
24. M. A. Syed, S. Baber, A. S. Bhatti, and H. Bukhari, Antibacterial
effects of silver nanoparticles on the bacterial strains isolated from
catheterized urinary tract infection cases. J. Biomed. Nanotechnol.
5, 209 (2009).
25. Y. S. Chen, Y. C. Hung, I. Liau, and G. S. Huang, Assessment of the
in vivo toxicity of gold nanoparticles. Nanoscale Res. Lett. 4, 858
(2009).
26. K. L. Dreher, Health and environmental impact of nanotechnology:
Toxicological assessment of manufactured nanoparticles. Toxicol.
Sci. 77, 3 (2004).
27. L. Zhang, Y. Jiang, Y. Ding, M. Povey, and D. York, Investigation
into the antibacterial behavior of suspensions of suspensions of ZnO
nanoparticles (ZnO nanofluids). J. Nanopart. Res. 9, 479 (2007).
28. V. Wiwanitkit, A. Sereemaspun, and R. Rojanathanes, Effect of gold
nanoparticles on spermatozoa: The first world report. Reprod. Biol-
ogy. 91, 1 (2007).
29. R. Bhattachrya and P. Mukherjee, Biologcal prtoperties of ‘naked’
nanoparticles. Add. Drug. Deliv. Rev. 60, 1289 (2008).
30. O. H. Lu, K. L. Yao, D. Xi, Z. L. Liu, X. P. Luo, and Q. Ning,
Synthesis and characterization of composite nanoparticles comprised
of gold shell and magnetic core/core. J. Magn. Magn. Mater. 301, 44
(2006).
31. X. Ji, R. Shao, A. M. Elliot, R. J. Stafford, E. E. Coss, J. A.
Bankson, G. Liang, Z. P. Luo, K. Park, J. T. Markert, and C. Li,
Bifunctional gold nanoshells with a superparamagnetic Iron oxide-
silica core suitable for both MRI imaging and photothermal therapy.
J. Phys. Chem. C 111, 6245 (2007).
J. Biomed. Nanotechnol. 7, 1–9, 2011 7
REVIEW
Development of Rapid Diagnostic Methodologies for Microbial Detection Syed and Bukhari
32. A. J. D. Pasqua, R. E. Mishler, Y. L. Ship, J. C. Dabrowiak, and
T. Asefa, Preparation of antibody conjugated gold nanoparticles.
Mater Lett. 63, 1876 (2009).
33. P. Baptista, E. Pereira, and P. Eaton, Gold nanoparticles for the
development of clinical diagnostic methods. Anal. Bioanal. Chem.
391, 943 (2009).
34. E. Liandris, M. Gazouli, M. Andreadou, M. Éomor, M. A. L. A.
Sechi, and J. Ikonomopoulos, Direct detection of unamplified DNA
from pathogenic mycobacteria using DNA-derivatized gold nanopar-
ticles. J. Microbiol. Meths. 78, 260 (2009).
35. C. A. Mirkin, R. L. Letsinger, R. C. Mucic, and J. J. Storhoff,
A DNA based method for rationally assembling nanoparticles into
macroscopic materials. Nature 382, 607 (1996).
36. S. H. Huang, Gold nanoparticle-based immunochromatographic
assay for the detection of staphylococcus aureus.Sens. Actuator, B
127, 335 (2007).
37. S. Cui, C. Chen, and G. Tong, A simple and rapid immunochro-
matographic strip test for monitoring antibodies to H5 subtype avian
influenza virus. J. Virol. Methods. 152, 102.
38. S. Cui, S. Zhou, C. Chen, T. Qi, C. Zhang, and J. Oh, A simple and
rapid immunochromatographic strip test for detecting antibody to
porcine reproductive and respiratory syndrome virus. J. Virol. Meth-
ods. 152, 28
39. F. Peng, Z. Wang, S. Zhang, R. Wu, S. Hu, Z. Li, X. Wang,
and X. Bi, Development of an immunochromatographic strip for
rapid detection of H9 subtype avian influenza viruses. Clin. Vaccine
Immunol. 15, 569 (2008).
40. D. A. Bautista, S. Elanakumaran, J. A. Arking, and R. A. Heckert,
Evaluation of an immunochromatography strip assay for the detec-
tion of salmonella species from poultry. J. Vet. Diagn. Invest. 14, 427
(2002).
41. G. Mayer, Chemical biology of aptamers. Angew. Chem. Int. Edit.
48, 2672 (2009).
42. H. Xu, X. Mao, Q. Zeng, S. Wang, A. N. Kwade, and G. Liu,
Aptamer functionalized gold nanoparticles as probes in dry
reagent strip biosensor for protein analysis. Anal. Chem. 81, 669
(2009).
43. J. J. Storhoff, S. S. Marla, P. Bao, S. Hagenow, H. Mehta, A. Lucas,
V. Garimella, T. Patno, W. Buckingham, W. Cork, and U. R.
Müller, Goldnanoparticle-based detection of genomic DNA targets
on microarrays using a novel optical detection system. Biosens. Bio-
electrons. 19, 875 (2004).
44. C. A. Mirkin, R. L. Letsinger, R. C. Mucic, and J. J. Storhoff, Nature
382, 607 (1996).
45. Y. Uludag, R. Hammond, and M. A. Cooper, A signal amplification
assay for HSV type 1 viral DNA detection using nanoparticles and
direct acoustic profiling. J. Nanobiotechnol. 8(2010).
46. M. X. He, K. Li, J. H. Xiao, and Y. X. Xhou, Rapid bio-barcode
assay for multiplex DNA detection based on capillary DNA analyzer.
J. Virol. Methods. 151, 126 (2008).
47. S. I. Stoeva, J. S. Lee, C. S. Thanxton, and C. A. Mirkin, Multiplexed
DNA detection with biobarcoded nanoparticle probes. Angew. Chem
Int. Edit. 3303 (2006).
48. D. Clarke, Bio-barcode-based DNA detection. Drug Discov. Today
3, 129 (2004).
49. D. Zhang, D. J. Carr, and E. C. Alocilja, Fluorescent bio-barcode
DNA assay for the detection of salmonella enterica serovar enteri-
tidis. Biosens. Bioelectrons 24, 1377.
50. T. S., J. Zhao, J. J. Storhoff, P. J. Norris, R. F. Little, R. Yarchoan,
S. L. Stramer, T. Patno, and I. K. Helett, Nanoparticle-based bio-
barcode amplification assay (BCA) for sensitive and early detection
of human immunodeficiency type 1 capsid (p24) antigen. J. Acquir.
Defic. Syndr. 46, 231 (2007).
51. L. Chen, H. Wei, Y. Guo, Z. Cui, Z. Zhang, and X. Zhang, Gold
nanoparticle enhanced immuno-PCR for ultrasensitive detection of
Hantaan virus nucleocapsid protein. J. Immunol. Methods 346, 64
(2009).
52. C. M. Niemeyer, M. Adler, and R. Wacker, Immuno-PCR: High
sensitivity detection of proteins by nucleic acid amplification. Trends
Biotechnol. 23, 208 (2005).
53. A. McKie, D. Samuel, B. Cohen, and N. A. Saunders, A quantita-
tive immuno PCR assay for the detection of mumps specific IgG.
J. Immunol. Methods 270, 135 (2002).
54. J. M. Barletta, D. C. Edelman, and N. T. Constantine, Immunomag-
netic quantitative immuno-PCR for detection of less than one HIV-1
virion. J. Virol. Methods 127, 154 (2005).
55. U. Yogeswaran and S. M. Chen, A review of the electrochemical
sensors and biosensors composed of nanowires as sensing material.
Sensors 290 (2008).
56. Y. G. Guo, Y. F. Zhou, X. E. Zhang, Z. P. Zhang, Y. M. Qiao, L. J.
Bi, J. K. Wen, M. F. Liang, and J. B. Zhang, Phage display mediated
immuno-PCR. Nucleic Acids Res. 348, 1 (2006).
57. S. Brakmann, DNA based barcodes, nanoparticles and nanostructures
for the ultrasensitive detection and quantification of proteins. Angew.
Chem. Int Ed. 43, 5730 (2004).
58. J. Shah and E. Wilkins, Electrochemical biosensors for detection of
biological warfare agents. Electroanal. 15, 157 (2002).
59. D. Grieshaber, R. MacKenzie, J. Vörös, and E. Reimhult, Electro-
chemical biosensors—Sensor principles and architectures. Sensors
8, 1400 (2008).
60. D. Ivnitski, I. Abdel-Hamid, P. Atanasov, E. Wilkins, and Stricker,
Application of electrochemical biosensors for detection of food
pathogenic bacteria. Electroanal. 12, 317 (2000).
61. J. M. Pingarrón, P. Yáñez-Sedeño, and A. González-Cortés, Gold
nanoparticle-based electrochemical biosensors. Electrochim. Acta.
53, 5848 (2008).
62. M. U. Ahmed, M. M. Hossain, and E. Tamiya, Electrochemical
biosensors for medical and food applications. Electroanal. 20, 616
(2008).
63. Y. Zhang, K. Zhang, and H. Ma, Electrochemical DNA biosensors
based on gold nanoparticles/cysteamine/poly(glutamic acid) modi-
fied electrode. Am. J. Biomed. Sci. 1, 115 (2009).
64. L. Wang, Q. Wei, C. Wut, J. Ji, and P. Wang, Proceedings of the
2007 International Conference on Information Acquisition, Jeju City,
Korea, July (2007).
65. V. Nanduri, A. K. Bhunia, S. I. Tu, G. C. Paoli, and J. D. Brewster,
SPR biosensor for the detection of L. monocytogenes using phage-
displayed antibody. Biosens. Bioelectrons 23, 248 (2007).
66. J. Yuan, R. Oliver, J. Li, J. Lee, M. Aguilar, and Y. Wu, Sensi-
tivity enhancement of SPR assay of progesterone based on mixed
self-assembled monolayers using nanogold particles. Biosens. Bio-
electrons 23, 144 (2007).
67. F. C. Dudak and I. H. Boyac, Rapid and label-free bacteria detec-
tion by surface plasmon resonance (SPR) biosensors. Biotechnol. J.
4, 1003 (2009).
68. C. Cao and S. J. Sim, Signal enhancement of surface plasmon reso-
nance immunoassay using enzyme precipitation-functionalized gold
nanoparticles: A femto molar level measurement of anti-glutamic
acid decarboxylase antibody. Biosens. Bioelectron. 22, 1874
(2007).
69. B. Barlen1, S. D. Mazumdar, O. Lezrich, P. Kämpfer, and
M. Keusgen, Detection of salmonella by surface plasmon resonance.
Sensors 7, 1427.
70. J. S. Mitchell, Y. Wu, C. J. Cook, and L. Main, Sensitivity enhance-
ment of surface plasmon resonance biosensing of small molecules.
Anal. Chem. 343, 125 (2005).
71. M. Arruebo, M. Valladares, and A. F. ‘Lez-Ferna’ndez, Antibody-
conjugated nanoparticles for biomedical applications. J. Nanometer.
1(2009).
72. J. Riu, A. Maroto, and F. X. Rius, Nanosenors in environmental
analysis. Talanta 69, 288 (2006).
8J. Biomed. Nanotechnol. 7, 1–9, 2011
REVIEW
Syed and Bukhari Development of Rapid Diagnostic Methodologies for Microbial Detection
73. T. Vo-Dinh, B. M. Cullum, and D. L. Stokes, Nanosensors and
biochips: Frontiers in biomolecular diagnostics. Sensor. Actuator. B-
Chem. 74, 2 (2001).
74. E. Y. Bridson and G. W. Gould, Quantal microbiology. Lett. Appl.
Microbiol. 30, 95 (2001).
75. R. A. Tripp, R. A. Dluhy, and Y. Zhao, Novel nanostructures for
SERS biosensing. Nanotoday 3, 31 (2008).
76. Y. S. Huh, A. J. Chung, and D. Erickson, Surface enhanced Raman
spectroscopy and its application to molecular and cellular analysis.
Microfluid Nanofluid. 6, 385 (2009).
77. J. B. Jackson and N. J. Halas, Surface-enhanced Raman scattering
on tunable plasmonic nanoparticle substrates. P. Natl. Acad. Sc. USA
101, 17930 (2004).
78. J. D. Driskell and R. A. Tripp, Emerging technologies in
nanotechnology-based pathogen detection. Clin. Micbrobiol. Newsl.
31, 137 (2009).
79. I. S. Patel, W. R. Premasiri, D. T. Moir, and L. D. Ziegler, Barcoding
bacterial cells: A SERS based methodology for pathogen identifica-
tion. J. Raman Spectrosc. 39, 1660 (2008).
80. S. Shanmukh, L. Jones, Y. P. Zhao, J. D. Driskell, R. A. Tripp,
and R. A. Dluhy, Identification and classification of respira-
tory syncytial virus (RSV) strains by surface-enhanced Raman
spectroscopy and multivariate statistical techniques. 390, 1551
(2008).
81. H. W. Cheng, S. Y. Huan, H. L. Wu, G. L. Shen, and R. Q.
Yu, Surface-enhanced Raman spectroscopic detection of a bacte-
ria biomarker using gold nanoparticle immobilized substrates. Anal.
Chem. 81, 9902 (2009).
82. R. C. Stringer, S. Schommer, D. Hoehn, and S. A. Grant, Develop-
ment of an optical biosensor using gold nanoparticles and quantum
dots for the detection of porcine reproductive and respiratory syn-
drome virus. Sens. Actuator, B 134, 427 (2008).
Received: 20 September 2010. Revised/Accepted: 23 November 2010.
J. Biomed. Nanotechnol. 7, 1–9, 2011 9
