The document discusses the evolution and principles of biosensors, outlining their historical development, key components, and types of biopolymers used in their construction. Biosensors are analytical devices that convert biological responses into electrical signals and are essential for various applications. Additionally, the text covers nanomaterials, their classification, properties, and uses in fields like medicine and electronics.

1. Future trends in
green
chemistry
BIOSENSORS

2. History of biosensors
 M. Cremer established that the concentration of an acid
in a liquid is proportional to the electric potential that
occurs between segments of the fluid positioned on
opposite sides of a glass membrane.
 Yellow spring instruments eventually created the first
commercial biosensor in 1975. The first immunosensor,
ovalbumin or egg protein on a platinum wire, and the
microbe biosensor paved the way for modern detection
in 1975 In the realm of biosensors, considerable
progress has been made since the development of the
i-STAT sensor.

3. What is biosensor?
 Biosensors are analytical devices that convert
a biological response into an electrical signal.
 Biosensors must be highly specific,
independent of physical parameters such as
pH and temperature and should be reusable.
 The term “biosensor”
was coined by Cammann

4.  Fabrication of biosensors, its materials,
transducing devices, and immobilization methods
requires multidisciplinary research in chemistry,
biology, and engineering.
 The materials used in biosensors are categorized
into three groups based on their mechanisms:
1. bio catalytic group comprising enzymes
2. bio affinity group including antibodies and nucleic
acids
3. microbe based containing microorganisms.

5. Basic principle of biosensors
 Basic priciple of biosensor involved in three element :-
1. First biological recognization element which highly
specific towards the biological material analytes
produces.
2. Second transducess detect and transduces signal from
biological target - receptor molecule to electrical signal
which is due to reaction occur.
3. Third after transduction sinal from biological to electrical
signal where its amplification is necessary and takes
place and read out in detector after processing the
values are displayed for monitor and controlling the
system.

8. A typical biosensor
is represented in it consists of the
following components.
 Analyte: A substance of interest that needs detection. For instance,
glucose is an ‘analyte’ in a biosensor designed to detect glucose.
 Bioreceptor: A molecule that specifically recognises the analyte is
known as a bioreceptor. Enzymes, cells, aptamers, deoxyribonucleic
acid (DNA) and antibodies are some examples of bioreceptors. The
process of signal generation (in the form of light, heat, pH, charge or
mass change, etc.) upon interaction of the bioreceptor with the
analyte is termed bio-recognition.
 Transducer: The transducer is an element that converts one form of
energy into another. In a biosensor the role of the transducer is to
convert the bio-recognition event into a measurable signal. This
process of energy conversion is known as signalisation. Most
transducers produce either optical or electrical signals that are
usually proportional to the amount of analyte–bioreceptor
interactions.

9.  Electronics: This is the part of a biosensor that processes the
transduced signal and prepares it for display. It consists of
complex electronic circuitry that performs signal conditioning
such as amplification and conversion of signals from analogue
into the digital form. The processed signals are then quantified
by the display unit of the biosensor.
 Display: The display consists of a user interpretation system
such as the liquid crystal display of a computer or a direct printer
that generates numbers or curves understandable by the user.
This part often consists of a combination of hardware and
software that generates results of the biosensor in a user-friendly
manner. The output signal on the display can be numeric,
graphic, tabular or an image, depending on the requirements of
the end user.

10. Common bioreceptors

14. Biopolymers
 Biopolymers are polymers that are produced by or
derived from living organisms, such as plants and
microbes, rather than from petroleum, the traditional
source of polymers. The primary sources
of biopolymers are renewable.
 Many, but not all, biopolymers are biodegradable,
which means they ‘are capable of decomposing
into carbon dioxide,
methane, water, inorganic compounds or
biomass by the enzymatic action of microorganisms’

15. Classes of biopolymers
 There are three main classes of biopolymers, classified according to the
monomers used and the structure of the biopolymer
formed: polynucleotides, polypeptides, and polysaccharides.
 The Polynucleotides, RNA and DNA, are long polymers of nucleotides.
 Polypeptides include proteins and shorter polymers of amino acids; some
major examples include collagen, actin, and fibrin. Polysaccharides are
linear or branched chains of sugar carbohydrates; examples include
starch, cellulose, and alginate.
 Other examples of biopolymers include natural rubbers (polymers
of isoprene), suberin and lignin (complex polyphenolic polymers),
 cutin and cutan (complex polymers of long-chain fatty acids), melanin,
and polyhydroxyalkanoates (PHAs).

16. Types of biopolymers

17. Types of biopolymers
 Biopolymers can be classified according to various scales. These
classifications are based on their origin, a number of monomeric
units, on the basis of degradability, their heat response etc.
Some of the classifications are:
 On the Basis of Type
1. Sugar-based polymers- Starch or sucrose is used as input for
manufacturing. Lactic acid polymers are created using lactose
from potatoes, maise, etc.
2. Starch-based polymers- Starch acts as a natural polymer,
composed of glucose. It is found in plant tissues.
3. Cellulose-based biopolymers- Used for packaging, this
polymer is made up of glucose obtained from natural sources
like cotton. Eg. cellophane.
4. Synthetic materials- Degradable polymers can be made from
synthetic materials obtained from petroleum.

18.  On the Basis of Origin
1. Natural biopolymers- These are natural biopolymers
biosynthesised by living organisms.
2. Synthetic biopolymers - These are polymers made up of
renewable materials like polylactic acid which are
degradable.
3. Microbial- Biopolymers produced by microorganisms.
 On the Basis of Monomeric Units
1. Polysaccharides-These are carbohydrate chains which are
branched or are linear: Eg. starch, cellulose, etc.
2. Proteins- Polymers made up of amino acids. Eg. collagen,
fibrin etc.
3. Polynucleotides - Nucleic acids are long polymer chains
composed of 13 or more monomeric units. Eg. DNA, RNA
etc.

20. Nanomaterials
 Nanomaterials can be characterized by a variety of scattering techniques. The
simplest, most direct method is x-ray scattering, which can be used to
investigate the phase and particle size. The particle size can be estimated from
the width of the diffraction peaks using the Scherrer equation:
𝐷=𝜅𝜆/𝛽cos𝜃
 where D is the average crystallite size perpendicular to the reflecting planes
 λ is the x-ray wavelength
 θ is the Bragg angle
 β is the width of the peak in radians due to the finite size of the crystal, and κ is
a constant close to unity.
 Because strain also broadens the x-ray lines, more complicated methods are
needed to make a precise measurement of the average particle size.
 Klug and Alexander (1974) provide a method for separating size effects from
strain.

21.  Nano-sized particles exist in nature and can be created from a
variety of products, such as carbon or minerals like silver, but
nanomaterials by definition must have at least one dimension that is
less than approximately 100 nanometers. Most nanoscale materials
are too small to be seen with the naked eye and even with
conventional lab microscopes.
 Materials engineered to such a small scale are often referred to as
engineered nanomaterials (ENMs), which can take on unique
optical, magnetic, electrical, and other properties. These emergent
properties have the potential for great impacts in electronics,
medicine, and other fields. For example,
1. Nanotechnology can be used to design pharmaceuticals that can
target specific organs or cells in the body such as cancer cells,
and enhance the effectiveness of therapy.
2. Nanomaterials can also be added to cement, cloth and other
materials to make them stronger and yet lighter.
3. Their size makes them extremely useful in electronics, and they
can also be used in environmental remediation or clean-up to bind
with and neutralize toxins.

22. Types of nanomaterials

23. Where are nanomaterials
found?
 Some nanomaterials can occur naturally, such as blood
borne proteins essential for life and lipids found in the
blood and body fat.
 Scientists, however, are particularly interested in
engineered nanomaterials (ENMs), which are designed
for use in many commercial materials, devices and
structures.
 already, thousands of common products-- including
sunscreens, cosmetics, sporting goods, stain-resistant
clothing, tires, and electronics—are manufactured
using ENMs.
 They are also in medical diagnosis, imaging and drug
delivery and in environmental remediation.

24. Types of nanomaterials
 Nanomaterials can be categorized into four types such as:
1. inorganic-based nanomaterials
2. carbon-based nanomaterials
3. organic-based nanomaterials
4. composite-based nanomaterials.
 Generally, inorganic-based nanomaterials include different metal and
metal oxide nanomaterials. Examples of metal-based inorganic
nanomaterials are silver (Ag), gold (Au), aluminum (Al), cadmium (Cd),
copper (Cu), iron (Fe), zinc (Zn), and lead (Pb) nanomaterials, whereas
examples of metal oxide-based inorganic nanomaterials are zinc
oxide (ZnO), copper oxide (CuO), magnesium aluminum oxide (MgAl2O4),
titanium dioxide (TiO2), cerium oxide (CeO2), iron oxide (Fe2O3), silica
(SiO2), and iron oxide (Fe3O4), etc.

25.  Carbon-based nanomaterials include graphene, fullerene,
single-walled carbon nanotube, multiwalled carbon
nanotube, carbon fiber, an activated carbon, and carbon
black.
 The organic-based nanomaterials are formed from
organic materials excluding carbon materials, for
instance, dendrimers, cyclodextrin, liposome, and micelle.
 The composite nanomaterials are any combination of
metal-based, metal oxide-based, carbon-based, and/or
organic-based nanomaterials, and these nanomaterials
have complicated structures like a metal-organic
framework.