Biosensors: Components and Applications-A Review

Shahid Ahmad Dar1, Mohd Sharjeel Sofi2, Sajad Ahmad Dar3,

Masarat Nabi4
1,2,4
Department of Environmental Science, University of Kashmir, Srinagar-190006, (India)

3
Department of Environmental Science, Bhagwant University Ajmer, (India)

ABSTRACT

Biosensors are analytical tools for the analysis of bio-material samples to gain an understanding of their bio-
composition, structure and function by converting a biological response into an electrical signal. The device
consists of two main parts: A bioreceptor and a transducer. Bioreceptor is a biological component that
recognizes the target analyte and transducer is a physicochemical detector component that converts the
recognition event into a measurable signal. The transducer is a physicochemical detector component that
converts the recognition event into a measurable response. Biosensors can have a variety of biomedical,
industry, and military applications. The applications of biosensors include Food Analysis, Study of
biomolecules and their interaction, Drug Development, Crime detection, Medical diagnosis (both clinical and
laboratory use) Environmental field monitoring Quality control, Industrial Process Control, Detection systems
for biological warfare agents, Manufacturing of pharmaceuticals and replacement organs. The characteristic
features which impart high order relevance to the biosensors in the present contemporary world are their
selectivity, sensitivity, stability, reproducibility and low cost. This article reviews the brief history, basic
principles, and the various types’ of biosensors available and their applications.

Keywords: Analyte, Applications, Bioreceptor, Biosensor, Transducer,

1. INTRODUCTION

A biosensor is an analytical device, used for the detection of an analyte that combines a biological component
with a physicochemical detector. Biosensors represent biophysical devices which will detect the presence and
measure the quantities of specific substances in a variety of environment (Heineman et al., 1918-2005) [1].
These specific substances may include sugars, proteins or hormones in human body, pollutants in abiotic
components of the environment including air, soil and water and a variety of toxins in the industrial effluents. In
designing a biosensor an enzyme or an antibody or even microbial cells are associated with microchip devices
which are used for quantitative estimation of a substance. The biologically sensitive elements can also be
created by biological engineering. The transducer or the detector element, which transforms one signal into
another one, works in a physicochemical way: optical, piezoelectric, electrochemical, electro-

414 | P a g e
chemiluminescence etc., resulting from the interaction of the analyte with the biological element, to easily
measure and quantify (Cavalcanti et al., 2008) [2].

2. COMPONENTS OF BIOSENSOR

Biosensor today is an analytical tool which consists of biological material in intimate contact with a transducer
(Fig.1). A biosensor typically consists of a bio-recognition site, biotransducer component, and electronic system
which includes a signal amplifier, processor, and display. It combines high selectivity of biological/ chemical
material with high accuracy of solid state devices. However, interfacing poses difficult problems. The biological
material can be membrane, enzyme, antibody/antigen, receptor, protein, intact cells, tissue or whole organ. It is
necessary that the analyte should reach the reaction site in the biological material.

Analyte Bioreceptor Transducer Measurable

signal
Enzyme Electroactive Electrode
substance
Antibody Semiconductor
pH Change pH electrode
Micro- Detector
Heat Thermistor
organism
Light Photon
Cell Counter
Piezoelectric
Mass change Device

Fig.1. Schematics of a biosensor

3. CLASSIFICATION OF BIOSENSORS

Biosensors can be classified according to transducers employed. The transducers are of different
types:

 Electrochemical
 Optical
 Calorimetric
 Piezoelectric
 Microbial biosensor
 Enzyme biosensor

415 | P a g e
3.1 Electrochemical transducer

Potentiometric or amperometric are most popular because of their familiarity to chemists and biologists as well
as simplicity of operation. It has added advantage that the same device can be used to sense different types of
redox molecules, provided their redox potentials are distinctly different from one another (jolly et al., 2015) [3].

3.2 Optical biosensors

Light is focussed on a membrane containing reagents which can combine with target molecules diffusing
through membrane. As a result, reagents can absorb or fluorescence, which is, measured and thereby
concentrations of target molecules are determined.

3.3 Calorimetric

Biosensors based on bioanalytical calorimetry rest upon the fact that most of the biological reactions are
exothermic. Most of the reactions are associated with high molar enthalpy changes (20-100KJ per mol) in a
single enzymatic step. An enzyme immobilized electrode coupled to calorimetric device forms thermometric
sensor. These are simple in operation, insensitive to optical properties of sample and possess high specificity.

3.4 Piezoelectric

Piezoelectric sensors utilise crystals which undergo an elastic deformation when an electrical potential is applied
to them. An alternating potential (A.C.) produces a standing wave in the crystal at a characteristic frequency.
This frequency is highly dependent on the elastic properties of the crystal, such that if a crystal is coated with a
biological recognition element the binding of a (large) target analyte to a receptor will produce a change in the
resonance frequency, which gives a binding signal. In a mode that uses surface acoustic waves , the sensitivity is
greatly increased. This is a specialised application of the quartz crystal microbalance as a biosensor

3.5 Microbial biosensor

Microbial biosensors consist of a number of coupled or uncoupled enzymic steps. These are less sensitive to
inhibitors and highly tolerant of variations in pH and temperature. These are cheaper and have long life times.

3.6 Enzyme biosensors

An enzyme biosensor is an analytical device that combines an enzyme with a transducer in order to produce a
signal proportional to target analyte concentration. Enzyme - based sensors are more specific than cell based
sensors. They have faster responds due to shorter diffusion paths. They are expensive to produce due to the
problem of isolating the enzyme. Glucose biosensor is mostly used biosensor.

416 | P a g e
4. APPLICATIONS OF BIOSENSORS

4.1 Biosensors in food industry

A gruelling difficulty in food processing industry is of quality and safety, maintenance. Traditional techniques
have shortcomings due to human fatigue, they are costly and time consuming. Hence there arises the need for
food authentication and monitoring with objective and consistent measurement of food products in the food
industry. Thus development of biosensors in response to the demand for simple, concurrent, selective and
inexpensive techniques is apparently promising. (Sharma et al., 2015) [4]. The Potential applications of enzyme
based biosensors to food quality control include measurement of amino acids, amines, amides, heterocyclic
compounds, carbohydrates, carboxylic acids, gases, cofactors, inorganic ions, alcohols, and phenols (Despande
et al., 2014) [5]. Biosensors can be used in industries such as wine beer, yogurt, and soft drinks producers.
Immunosensors have important potential in ensuring food safety by detecting pathogenic organisms in fresh
meat, poultry, or fish (Kress, 1998) [6]. Enzymatic biosensors are also employed in the dairy industry. A
biosensor, based on a screen-printed carbon electrode, was integrated into a flow cell. (Mishra et al., 2012) [7].
Enzymes were immobilized on electrodes by engulfment in a photocrosslinkable polymer. The automated flow-
based biosensor could measure the concentration of three organophosphate pesticides in milk.

4.2 Biosensors as a Diagnostic tool:

Recent advances in bioanalytical sensors have led to the utilization of the ability of certain biosensors in the
early diagnosis of a range of diseases. Biosensors can be used to define disease type, state or progress as well as
the patient’s response to treatment. The most commonly used sample type for biosensors in diagnostic
applications has been serum, but in the last few years other body fluids, such as urine and saliva, are
increasingly investigated. Furthermore, the biosensors allow a closer investigation of the state of their origin.
Urine samples, for example, may provide more information about current state of kidney and bladder than
serum samples (Echeverry et al., 2010) [8]. Biosensor measurements using cerebrospinal fluid (CSF) have also
been attaining the attention in recent years due to potential bio-markers in CSF allowing early detection of
neurodegenerative diseases, such as Alzheimer’s disease. It is a proven fact that certain biomarkers exist which
are significant for certain diseases, such as increased levels of blood glucose typically indicate diabetes (Yoo
and Lee , 2010) [9]. Valentini et al. developed a glucose biosensor using gold microelectrodes coated via
Single-Walled Carbon Nanotubes (SWCNTs), by the Electrophoresis Deposition Process. Нis nanostructured
biosensor was successfully utilized to layer a poly (pyrrole)/glucose oxidase film. A highly extended linear
concentration (ranging from 4 mM to 100 mM) of biosensor offered the opportunity to determine glucose level
from 0.560 mM to 12.0 mM, with a high detection limit of 50 µM (useful for hypo-glycemia disease) (Valentini
et al., 2013) [10]. The transducer, in a biosensor converts the molecular recognition signal to an electrical
signal. It may be electrochemical, optical, calorimetric or based on mass changes (Zhang et al., 2013) [11].
The electrochemical biosensors detect an electrical response when there is a molecular recognition of a specific
element. For an example- detection of cancer marker hPRL-3 in breast cancer cells (Jia et al., 2007) [12]. By

417 | P a g e
utilizing specific DNA sequences, it is possible to recognize elements in cancer and/or conjoined with genetic
mutations. BRCA1 and BRCA2 mutations are associated with hereditary breast cancer. This type of biosensor
has the ability to detect damaged DNA and carcinogens associated with the damage (Bohunicky and Mousa,
2010) [13]. The use of biosensors in the early detection of cancer and monitoring the overall progress of disease
state is the hopeful keys for the effective treatment, thus reducing the mortality rate of the patients.

4. 3 Biosensors in Environmental Monitoring:

The environmental monitoring has been one of the priorities in almost all the countries due to the close
relationship between the environmental pollution and the human health/socioeconomic development. The
biosensors have been widely employed as cost-effective, fast, in situ, and real-time analytical techniques for
combating the increasing number of pollutants. Biosensors including immunosensors, aptasensors, genosensors,
and enzymatic biosensors have been reported for the detection and monitoring of various environmental
pollutants, using antibodies, aptamers, nucleic acids, and enzymes as recognition elements (Van et al., 2010)
[14]. Gold nanoparticles (GNPs) with controlled geometrical, optical, and surface chemical properties have
great potential applications in environmental detection. GNPs can be easily modified with biomolecules. GNP-
based optical sensors have been used to detect environmental pollutants including heavy metals, toxins, and
other pollutants. Liu et al. [15] used quaternary ammonium-functionalized GNPs to devise a colorimetric sensor
for Hg2+ detection. (Gavrilescu 2015) [16]. Surface Plasmon Resonance (SPR) is a surface-sensitive optical
technique that is used to detect environmental contaminants, including atrazine, Dichloro-Diphenyl-
Trichloroethane (DDT), 2,3,7,8-tetrachlorodibenzo-p-dioxin, carbaryl, 2,4-D, benzo[a]pyrene (BaP), biphenyl
derivatives, and trinitrotoluene (TNT), has recently gained considerable interest. Biosensors based on
luminescent bacteria are valuable tools for the online monitoring and early warning for surface and drinking
water. A multi-channel bioluminescent bacterial biosensor has been developed for the online detection of metals
and toxicity (Echeverry et al., 2010) [17]. For the detection of organophosphorous insecticides using paraoxon
as the model analyte, disposable amperometric enzymatic (acetylcholinesterase) biosensors were proposed using
a cysteamine self-assembled monolayer on gold screen-printed electrodes (Arduini et al., 2013) [18]. Another
organophosphorous pesticide, the methyl parathion, was determined by a sensitive and selective enzymatic
biosensor using hydrolase and a uniform nanocomposite based on magnetic Fe3O4 (average diameter of 120
nm) and gold nanoparticles (diameter ~13 nm). In order to detect the pollutants such as sulphur dioxide, (SO2),
methane, carbon dioxide etc, microbial biosensors have been developed. Thiobacillus-based biosensors are used
detect the pollutant SO2, whereas methane (CH4) can be detected by immobilized Methalomonas. A particular
strain of Pseudomonas is used to monitor carbon dioxide levels. Biological oxygen demand (BOD) is widely
used as a test to detect the levels of organic pollution. This requires five days of incubation but a BOD biosensor
using the yeast Trichosporon cutaneum with oxygen probe takes only 15 minutes to detect organic pollution.
4.4 Biosensors in Drug Discovery
Whether it is long-term monitoring or single shot analysis, biosensors find their use as technologically advanced
devices both in resource-limited settings and sophisticated medical set-ups: e.g.with applications in drug

418 | P a g e
 discovery(Bhalla et al., 2014) [19]. for the detection of a number of chemical and biological agents that are
considered to be toxic materials of defence interest( Paddle B.M, 1996) [20].
4.4 Biosensors in agriculture
The need for fast, on-line and accurate sensing opens up opportunities for biosensors in many different
agricultural areas -in situ analysis of pollutants in crops and soils, detection and identification of diseases in
crops and livestock. Biosensors play an important role in providing powerful analytical tools to the agricultural
diagnosis sector, particularly where rapid, low cost, high sensitivity and specificity measurements in field
situations are required.
The biosensors contribute in enhancing the production and quality of agricultural goods in following ways
 QCM (Quartz Crystaline Microbalancer) biosensor or acoustic biosensor is used
to detect phytopathogens such as Pseudomonas syringae pv. tomato,
Xanthomonas campestris pv. vesicatoria and Ralstonia solanacearum. SPR based immunosensor working on the
antigen and antibody interaction and it
helps in the diagnosis of rust in early stage of the disease that leads to control the disease by eco-friendly way.
 R (Surface Plasmon Resonance) is a devise used for rapid sensitivity detection of maize chlorotic mosaic virus
by using antibody and antigen concentration.
 E-nose consist of sensing element, signal collection unit and suitable pattern recognition algorithm. In
agricultural applications, the e-nose has been implemented successfully for the fruit ripeness determination,
detection of soil borne pathogens, inspection of fish etc.
5. CONCLUSIONS

Application of biosensors is enormously increasing in many areas of environmental monitoring and assessment.
There is a need to develop advanced biosensors based on modified base component and sensing elements which
should be reliable, simple in manufacturing and having the competence to widen the spectra of selectivity.

REFERENCES

[1]. Heineman W.R., Jensen W.B. Leland C. Clark Jr. (1918–2005) Biosens. Bioelectron. 2006;21:1403–1404.
doi: 10.1016/j.bios.2005.12.005.
[2]. Cavalcanti, A., Shirinzadeh, B., Zhang, M., & Kretly, L. C. (2008). Nanorobot hardware architecture for
medical defense. Sensors, 8(5), 2932-2958
[3]. Jolly P., Formisano N., Tkáč J., Kasák P., Frost C.G., Estrela P. Label-free impedimetric aptasensor with
antifouling surface chemistry: a prostate specific antigen case study. Sens. Actuators B. 2015;209:306–312. doi:
10.1016/j.snb.2014.11.083
[4]. Sharma T.K., Ramanathan R., Rakwal R., Agrawal G.K., Bansal V. Moving forward in plant food safety
and security through nanobiosensors: adopt or adapt biomedical technologies? Proteomics. 2015;15:1680–1692.
doi: 10.1002/pmic.201400503.
[5]. Despande, S.S.; Rocco, R.M. Biosensors and Their Potential Use in Food Quality Control. Food Technol.
1994, 48 (6), 146–150.

419 | P a g e
[6]. Kress-Rogers, E. Instrumentation and Sensors for the Food Industry; Woodhead Publishing Lmtd.:
Cambridge, England, 1998.
[7]. Mishra R., Dominguez R., Bhand S., Munoz R., Marty J. A novel automated flow-based biosensor for the
determination of organophosphate pesticides in milk. Biosens Bioelectron. 2012;32:56–61.
[8]. Echeverry G, Hortin GL, Rai AJ (2010) Introduction to urinalysis: historical perspectives and clinical
application. Methods Mol Biol 641:1-12
[9]. Yoo EH, Lee SY (2010) Glucose biosensors: an overview of use in clinical practice. Sensors 10:4558-4576
[10]. Valentini F, Galache Fernandez L, Tamburri E, Palleschi G (2013) Single walled carbon
nanotubes/polypyrrole-GOx composite films to modify gold microelectrodes for glucose biosensors: Study of
the extended linearity. Biosens Bioelectron 43: 75-78.
[11]. Zhang Y, Yang D, Weng L, Wang L (2013) Early lung cancer diagnosis by biosensors. Int J Mol Sci
14(8): 15479-15509.
[12]. Jia Y, Qin M, Zhang H, Niu W, Li X, et al. (2007) Label-free biosensor: anovel phage-modified Light
Addressable Potentiometric Sensor system for cancer cell monitoring. Biosens Bioelectron 22(12): 3261-3266.
[13]. Bohunicky B, Mousa SA (2010) Biosensors: the new wave in cancer diagnosis. Nanotechnol Sci Appl 4:
1-10.
[14]. Van Dorst B., Mehta J., Bekaert K., Rouah-Martin E., De Coen W., Dubruel P., et al. Recent advances in
recognition elements of food and environmental biosensors: a review. Biosens. Bioelectron. 2010;26:1178–
1194. doi: 10.1016/j.bios.2010.07.033.
[15]. Liu, D.B.; Qu, W.S.; Chen, W.W.; Zhang, W.; Wang, Z.; Jiang, X.Y. Highly sensitive, colorimetric
detection of mercury (II) in aqueous media by quaternary ammonium group-capped gold nanoparticles at room
temperature. Anal. Chem.2010, 82, 9606–9610. [Google Scholar]
[16]. Gavrilescu M., Demnerová K., Aamand J., Agathos S., Fava F. Emerging pollutants in the environment:
present and future challenges in biomonitoring, ecological risks and bioremediation. N.
Biotechnol. 2015;32:147–156. doi: 10.1016/j.nbt.2014.01.001.
[17]. Echeverry G, Hortin GL, Rai AJ (2010) Introduction to urinalysis: historical perspectives and clinical
application. Methods Mol Biol 641:1-12
[18]. Arduini, F.; Guidone, S.; Amine, A.; Palleschi, G.; Moscone, D. Acetylcholinesterase biosensor based on
self-assembled monolayer-modified gold-screen printed electrodes for organophosphorus insecticide detection.
Sens. Actuators B Chem. 2013, 179, 201–208.
[19]. Bhalla N., Di Lorenzo M., Pula G., Estrela P. Protein phosphorylation analysis based on proton release
detection: potential tools for drug discovery. Biosens. Bioelectron. 2014;54:109–114. doi:
10.1016/j.bios.2013.10.037.
[20]. Paddle B.M. Biosensors for chemical and biological agents of defence interest. Biosens.
Bioelectron. 1996;11:1079–1113. doi: 10.1016/0956-5663(96)82333-5.

420 | P a g e