BIOSENSORS TYPES WORKING AND APPLICATIONS unit-1 Biotechnology 6th sem

BIOSENSORS
by
Gudladona Raghava Ravali
M.pharm
Pharmaceutical Chemistry
JNTUK

BIOSENSORS
Biosensors are analytical devices that
detect and respond to biological or
chemical reactions, converting them
into measurable electrical or optical
signals. They are composed of a
biological recognition element (like an
antibody or enzyme) and a transducer
that converts the biological response
into a measurable signal.
Biosensors are used in various
applications, including disease
monitoring, drug discovery, and
environmental monitoring

WORKING OF BIOSENSORS
They consist of a biological
recognition element (like
an enzyme or antibody)
that interacts with a target
analyte, and a transducer
that converts this
interaction into a
detectable signal. This
signal is then processed
and displayed, providing
information about the
presence or concentration
of the analyte

Biological Recognition Element: This is the
key component that provides specificity to
the biosensor.
It can be:
Enzymes: They catalyze specific biochemical
reactions, and the change in substrate or
product concentration can be measured.
Antibodies: They bind to specific antigens
(target molecules), and this binding can be
detected.
Nucleic acids: They can be used to detect
DNA or RNA sequences through
hybridization.
Other biological molecules: Receptors,
cells, tissues, etc., can also be used as
biorecognition elements

Transducer: This element
converts the biological event
(analyte-bioreceptor interaction)
into a measurable signal. Different
types of transducers are used,
including:
Electrochemical
transducers: Measure changes in
electrical current, voltage, or
impedance.
Optical transducers: Measure
changes in light absorption,
reflection, or fluorescence.
Thermal transducers: Measure
heat changes produced during a
reaction.
Piezoelectric
transducers: Measure changes in
mass or frequency.

Signal Processing and Display: The signal from the
transducer is often weak and needs to be amplified and
processed before it can be displayed. Signal processing units
include filters, amplifiers, and other electronic
components. The final output is usually displayed as a
numerical value or a graph.

In essence, a biosensor works by:
1.Recognition: The biological element binds
to or interacts with the target analyte.
2.Conversion: This interaction causes a
change that the transducer can detect.
3.Signal Processing: The signal is amplified
and processed to provide a measurable
output.
4.Display: The processed signal is displayed,
indicating the presence or concentration of the
analyte.

Bioluminescent Biosensors
• A bioluminescence biosensor is a tool that uses light
produced by living organisms (bioluminescence) to detect
and measure specific substances or conditions. It leverages
the natural ability of certain organisms to emit light through
biochemical reactions, where a luciferase enzyme catalyzes
the oxidation of a luciferin substrate, producing light. These
biosensors are valuable because they can be highly
sensitive, offer reduced background noise compared to
fluorescence-based methods, and can be used in various
applications, including drug discovery, environmental
monitoring, and cellular studies.

Bioluminescent Biosensors
Bioluminescence:Living organisms like fireflies produce light through a chemical reaction
involving a luciferase enzyme and a luciferin substrate.
Biosensor Design:In a bioluminescent biosensor, this natural reaction is harnessed. The
biosensor is designed to include the bioluminescent system (luciferase and luciferin), and it's
linked to a biological system that responds to the target analyte (the substance being
measured).
Signal Generation:When the target analyte is present, it triggers a change in the biological
system, which then affects the bioluminescent reaction. This results in a change in the emitted
light intensity or other light characteristics (e.g., wavelength).
Detection and Measurement:The emitted light is then detected and measured, providing a
quantifiable signal that indicates the presence and concentration of the target analyte.

Electrochemical Biosensors:
Electrochemical biosensors
work by converting a biological
interaction into a measurable
electrical signal. This is
achieved by using a biological
recognition element (like an
enzyme or antibody) that
interacts with a target analyte
(like a specific molecule) and a
transducer that converts this
interaction into an electrical
signal, such as a change in
current or voltage.

Types of Electrochemical Biosensors:
Potentiometric Biosensors:
Measure the voltage difference at zero current flow, often used
for pH and ion concentration measurements.
Amperometric Biosensors:
Measure the current generated by an electrochemical reaction,
commonly used for glucose monitoring.
Conductometric Biosensors:
Measure changes in electrical conductivity due to the presence
of an analyte.
Impedimetric Biosensors:
Measure changes in electrical impedance, which can be related
to the binding of an analyte to a bioreceptor.

Optical Biosensors:
Optical biosensors work by detecting changes in the properties of light (like absorption, luminescence, fluorescence, or refractive
index) that occur when a target analyte interacts with a bioreceptor (like an enzyme, antibody, or cell) on the sensor's surface. This
interaction alters the light, and the change is measured and correlated with the analyte's concentration. Light Interaction:
Evanescent Wave:
Many optical biosensors utilize the evanescent wave, a light wave that decays exponentially as it penetrates the medium beyond a
reflective surface. This wave interacts with molecules near the surface, making it ideal for detecting interactions.
Optical biosensors can employ different optical phenomena, including:
Surface Plasmon Resonance (SPR): Changes in refractive index caused by molecular binding on a metal surface (often gold) are
detected by measuring shifts in reflected light.
Fluorescence: Fluorescent molecules (fluorophores) on the sensor surface emit light when excited by a specific
wavelength. Binding events can alter the fluorescence intensity or wavelength, which is then measured.
Refractive Index Changes: Binding events can alter the refractive index of the medium near the sensor surface, which can be
detected by measuring changes in light reflection or transmission.
Absorbance/Transmission: Changes in the absorption or transmission of light by the sensor can be used to detect binding
events.
Scattering: Changes in how light is scattered by the sensor surface can also be used to detect binding events.

Types Of optical Biosensors:
Surface Plasmon Resonance (SPR)
Biosensors:
Utilize the change in refractive index
at a metal surface to detect binding
events.
Fluorescence-based Biosensors:
Employ fluorescent dyes to detect
the presence and concentration of
analytes.
Optical Waveguide Biosensors:
Use changes in light intensity or
wavelength within a waveguide to
detect binding.

Piezoelectric Biosensors:
Piezoelectric biosensors are analytical
devices that utilize the piezoelectric effect
to detect changes in mass or mechanical
properties when a biological or chemical
substance interacts with a sensor
surface. They are based on the principle
that certain materials, when subjected to
mechanical stress, generate an electrical
charge, and conversely, when subjected to
an electrical field, they deform. This
conversion of mechanical energy to
electrical energy (and vice versa) is the
basis for their function.

Piezoelectric Biosensors:Working
The Piezoelectric Effect:
Piezoelectric materials, like quartz or certain ceramics, produce an electrical charge when
subjected to mechanical stress, such as pressure, force, or bending.
This effect also works in reverse: applying an electric field to these materials causes them to
deform or change shape.
How Piezoelectric Biosensors Work:
Affinity Interaction:
Piezoelectric biosensors are designed to detect specific interactions between a target analyte (the
substance being detected) and a biological recognition element (like an antibody, enzyme, or
DNA) attached to the sensor surface.
Mass Change Detection:
When the analyte binds to the recognition element, it causes a change in the mass of the sensor
surface.
Frequency Shift:
This change in mass affects the oscillation frequency of the piezoelectric crystal within the sensor.
Signal Measurement:
The frequency shift is measured by electronic circuitry, providing a direct correlation to the
amount of analyte present.

Types of Piezoelectric
Biosensors:
Quartz Crystal Microbalance
(QCM) Biosensors:
Measure changes in the
frequency of a quartz crystal due
to mass changes on its surface.
Surface Acoustic Wave (SAW)
Biosensors:
Utilize surface acoustic waves to
detect changes in mass or
properties of a surface.

Thermal Biosensors :Working
Thermal biosensors, also known as calorimetric or thermometric biosensors, are analytical
devices that detect biomolecules by measuring the heat generated or absorbed during a
biochemical reaction.
These sensors are based on the principle that biological reactions often involve a change in
temperature, either by releasing heat (exothermic) or absorbing heat (endothermic).
working:
1. Biological Reaction:A specific biological reaction, such as an enzyme-catalyzed reaction,
occurs between a target molecule (analyte) and a bioreceptor (e.g., enzyme, antibody).
2. Heat Change:
This reaction results in a change in temperature, either an increase (heat is released) or a
decrease (heat is absorbed).
3. Temperature Measurement:
The temperature change is then measured by a temperature-sensitive element like a
thermistor or thermocouple, which are integrated with the bioreceptor.
4. Signal Detection:
The measured temperature change is converted into an electrical signal, which can be used to
quantify the amount of the target molecule

Features of Thermal Biosensors
• Label-free: They don't require labeling the target molecule with a
fluorescent or radioactive tag, simplifying the detection process.
• High sensitivity: Can detect low concentrations of biomolecules.
• Rapid response: Offer relatively fast detection times.
• Real-time data: Provide continuous monitoring of biochemical
reactions.
• Insensitive to optical and electrochemical properties: Thermal
biosensors can be less affected by the optical or electrochemical
properties of the sample, making them suitable for a wider range of
applications.

Types of Thermal Biosensors
Calorimetric Biosensors:
Measure heat changes associated
with biochemical reactions.
Thermometric Biosensors:
Measure temperature changes
resulting from the interaction
between a bioreceptor and an
analyte

Other notable types of biosensors:
Enzyme Biosensors: Utilize enzymes as the bioreceptor to detect
specific substrates.
DNA Biosensors: Employ DNA or RNA as the biorecognition element to
detect complementary DNA or RNA sequences.
Immunosensors: Use antibodies as the biorecognition element to
detect specific antigens.
Whole Cell Biosensors: Utilize whole cells or microorganisms to detect
the presence of specific substances.
Magnetic Biosensors: Use magnetic nanoparticles or micro-magnets to
detect and quantify analytes

Pharmaceutical Applications Of Biosensors
Biosensors have diverse applications in the pharmaceutical industry, spanning
from drug discovery and development to bioprocess monitoring and
personalized medicine. They are used for detecting pathogens, monitoring
drug concentrations, and optimizing bioprocesses.
1. Drug Discovery and Development:
High-throughput screening:Biosensors can screen a large number of
compounds for their interaction with drug targets, accelerating the drug
discovery process.
Pharmacokinetics and pharmacodynamics studies:Biosensors help in
understanding how drugs are absorbed, distributed, metabolized, and
excreted in the body, as well as their effects.
Target identification and validation:Biosensors can be used to identify and
validate potential drug targets by analyzing the interactions of biomolecules.

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2. Diagnostics:
Infectious disease detection:Biosensors enable rapid and sensitive detection of pathogens like
bacteria, viruses, and fungi, aiding in timely diagnosis and treatment.
Disease monitoring:Biosensors are crucial for monitoring disease progression and treatment
efficacy in various conditions, including diabetes (glucose monitoring).
Personalized medicine:Biosensors help in tailoring drug therapies based on individual patient
characteristics, such as genetic makeup and disease stage.
3. Bioprocess Monitoring:
Fermentation monitoring:Biosensors are used to monitor key parameters like glucose, lactate, and
oxygen levels in fermentation processes, ensuring optimal conditions for biopharmaceutical
production.
Quality control:Biosensors ensure the quality and consistency of biopharmaceutical products by
monitoring critical attributes throughout the manufacturing process.
Real-time analysis:Biosensors provide real-time data on bioprocess parameters, allowing for
timely adjustments and optimization.

ADVANTAGES OF BIOSENSORS
1. High Sensitivity and Specificity: Biosensors can detect target analytes even at low
concentrations, even in complex samples, ensuring accurate and reliable results. They
are also highly specific, meaning they can distinguish between similar substances.
2. Rapid Detection: Biosensors can provide results within seconds to minutes, which is
crucial for real-time monitoring and quick decision-making in various applications like
disease diagnosis, food safety, and industrial process control.
3. Minimal Sample Preparation: Biosensors generally require minimal or no sample
preparation, simplifying the testing process and reducing the risk of contamination or
errors.
4. Portability and Ease of Use: Many biosensors are designed to be compact, portable,
and user-friendly, allowing for on-site and point-of-care testing.
5. Cost-Effectiveness: Biosensors can be more cost-effective than traditional analytical
methods, making them accessible for a wider range of users and applications.

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6. Real-time Monitoring: Biosensors enable continuous monitoring of analytes, providing
valuable data for various applications, including disease management, environmental
monitoring, and industrial process optimization.
7. Miniaturization and Wearable Applications: Biosensors can be miniaturized and integrated
into wearable devices, enabling continuous health monitoring, remote patient monitoring,
and personalized health solutions.
8. Versatile Applications: Biosensors find applications in diverse fields, including healthcare
(disease diagnosis, glucose monitoring), environmental monitoring (pollution detection), food
safety (pathogen detection, quality control), and industrial settings (process control, quality
assurance).
9. Improved Efficiency and Productivity: In industrial settings, biosensors can provide real-
time data and feedback on production processes, allowing for optimization of efficiency and
quality control.
10. Enhanced Safety: Biosensors can be used to detect harmful substances, such as toxins or
pathogens, in various environments, contributing to improved safety in healthcare, food
production, and other industries.

DIADVANTAGES OF BIOSENSORS
1. Short Shelf Life: The biological components (enzymes, antibodies, etc.) used in biosensors are prone to degradation, which can significantly shorten the sensor's
lifespan and limit its usability.
2. Susceptibility to Fouling: Biosensors can become contaminated by unwanted molecules from the sample being tested, leading to reduced sensitivity and
inaccurate readings.
3. Reproducibility Issues: It can be challenging to manufacture biosensors with consistent performance characteristics, potentially resulting in variability in
measurements.
4. High Cost: Some biosensors, particularly those using complex biological recognition elements or requiring sophisticated manufacturing processes, can be
expensive.
5. Complexity in Fabrication and Miniaturization: Developing biosensors that are both small and effective can be technically demanding, especially when
incorporating complex biological components.
6. Regulatory Approvals: The development and commercialization of biosensors can be subject to stringent regulatory requirements, which can add to the time
and cost involved.
7. Limited Temperature Range: Many electrochemical biosensors are sensitive to temperature variations, and their performance can be affected by fluctuations in
temperature, requiring stable temperature conditions.
8. Sensitivity Limitations: Some biosensors, especially those based on specific technologies like DNA biosensors, may have lower sensitivity compared to other
types.
9. Specificity Issues: While some biosensors offer high specificity, others may be susceptible to interference from similar molecules, leading to inaccurate readings.
10. Need for Optimization: The performance of many biosensors is dependent on optimizing various parameters like pH, temperature, and immobilization
techniques, which can require significant effort and resources.
11. Response Time: The time it takes for a biosensor to respond to an analyte can be a limiting factor in some applications, particularly in real-time monitoring
scenarios.
12. Interference and Noise: Biosensors can be affected by various forms of interference, including electromagnetic interference and noise, which can impact the
accuracy of measurements.
13. Stability Issues: Some biosensors, especially wearable sensors, may experience stability issues due to exposure to biofluids, leading to biofouling, chemical
changes, or irreversible non-specific adsorption.

BIOSENSORS TYPES WORKING AND APPLICATIONS unit-1 Biotechnology 6th sem

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BIOSENSORS TYPES WORKING AND APPLICATIONS unit-1 Biotechnology 6th sem