Aadrsh kumar tiwari bbau

“POLYMER IN TISSUE
ENGINNERING”
Aadrsh Tiwari

Biological scaffolds are derived from human, animal
tissues and synthetic scaffolds from polymers. The first
biologically active scaffold was synthesized in 1974.
Biomaterials play a critical role in this technology by
acting as synthetic frameworks referred as scaffolds,
matrices or constructs.
Biomaterials intended for biomedical applications target
to develop artificial materials that can be used to
renovate or restore function of diseased in the human
body and thus improve the quality of life.

BIOMATERIALS USED AS -
Implants in the form of sutures, bone plates, joint
replacements, ligaments, vascular grafts, heart
valves, intraocular lenses, dental implants, and
medical devices like pacemakers, biosensors, and
so forth.

Natural Polymers and Synthetic Polymers for
Scaffolds
biomedical applications, the criteria for selecting the
materials as biomaterials are based on their material
chemistry, molecular weight, solubility, shape and
structure, surface energy, water absorption degradation.

Polymeric scaffolds are drawing a great attention due to
their unique properties such as high surface-to-volume
ratio, high porosity with very small pore size,
biodegradation, and mechanical property.
Scaffold materials can be synthetic or biologic,
degradable or non degradable, depending on the
intended use. The properties of polymers depend on the
composition structure, and arrangement of their
constituent macromolecules.
It can be categorized into different types in terms of their
structural, chemical, and biological characteristics, for
example:- ceramics, glasses, polymers

Naturally occurring polymers, synthetic biodegradable,
and synthetic non biodegradable polymers are the main
types of polymers used as biomaterials.
Natural polymers can be considered as the first
biodegradable biomaterials used clinically.
Natural materials owing to the bioactive properties have
better interactions with the cells which allow them to
enhance the cells’ performance in biological system.
Natural polymers can be classified as proteins (silk,
collagen, gelatin, elastin, keratin), polysaccharides
(cellulose, dextran), or polynucleotides (DNA, RNA).

Synthetic biomaterial guidance provided by biomaterials
may facilitate restoration of structure and function of
damaged or diseased tissues.
Synthetic polymers are highly useful in biomedical field
since their properties (e.g., porosity, degradation time,
and mechanical characteristics) can be tailored
for specific applications.
Synthetic polymers represent the largest group of
biodegradable polymers, and they can be produced
under controlled conditions.

THREE DIMENSIONAL – POLYMERIC SCAFFOLDS
FABRICATIONAND DIFFERENT TYPE OF
SCAFFOLDS
In an era of decreasing availability of organs for
transplantation and a growing need for suitable
replacements, the emerging field of tissue engineering
gives hope to patients who desperately require tissue
and organ substitute.
scaffold characteristics can be tailored to the application
by careful selection of the polymers, additional scaffold
components, and the fabrication technique.

The fabrication technique for tissue engineering
scaffolds depends almost entirely on the bulk and
surface properties of the material and the proposed
function of the scaffold.
Polymer scaffolds can provide mechanical strength,
interconnected porosity and surface area, varying
surface chemistry, and unique geometries to direct
tissue regeneration .
Most techniques involve the application of heat and
pressure to the polymer or dissolving it in an
organic solvent to mold the material into its desired
shape.

fabrication techniques result in reproducible scaffolds for
the regeneration of specific tissues.
The method presents distinct advantages and
disadvantages, the appropriate technique must be
selected to meet the requirements for the specific type of
tissue.
scaffold designs have included meshes, fibers,
sponges and foams.
These designs are chosen because they promote
uniform cell distribution, diffusion of nutrients, and the
growth of organized cell communities

HYDROGELS SCAFFOLDS
Hydrogels have played an ever increasing role in the
revolutionary field of tissue engineering where they are
used as scaffolds to guide the growth of new tissues.
The design and application of biodegradable hydrogels
has dramatically increased the potential impact of
hydrogel materials in the biomedical field and enabled
the development of exciting advances in controlled drug
delivery and tissue engineering applications.
Hydrogels comprised of naturally derived
macromolecules have potential advantages of
biocompatibility, cell-controlled degradability, and
intrinsic cellular interaction.

Hydrogel’s are made either from synthetic or natural
polymers, which are cross linked through either covalent
or non covalent bonds.
Hydrogel’s in tissue engineering must meet a number of
design criteria to function appropriately and promote
new tissue formation.
Synthetic polymers can be prepared with precisely
controlled structures and functions.
Gels are formed when the network is covalently cross-
linked.

FIBROUS SCAFFOLDS
The development of nano-fiber’s has enhanced the
scope for fabricating scaffolds that can potentially mimic
the architecture of natural human tissue at the nano-
meter scale.
Electro spinning is the most widely studied technique
and also seems to exhibit the most promising results for
tissue engineering applications.
Nano-fibers synthesized by self-assembly and phase
separation have had relatively limited studies that
explored their application as scaffolds for tissue
engineering.

Nano-fibers used as scaffolds for musculoskeletal
tissue engineering including bone, cartilage, ligament,
and skeletal muscle, skin, vascular, neural tissue
engineering and as vehicle for the controlled delivery of
drugs, proteins and DNA .
The blending (or mixing) technique is a common choice
for the nano-fiber functionalization
The most popular and simplest nano-fiber modification
methods are physical blending and coating.
Natural polymers and synthetic polymers explored for
the fabrication of nano-fibers such as collagen
Gelatin, silk fibroin, PLA PLGA are fibrous scaffold in
biomedical application.

PORUS SCAFFOLDS
The three-dimensional polymeric porous scaffolds with
higher porosities having homogeneous interconnected
pore network are highly useful for tissue engineering.
Sponge or foam porous scaffold have been used in
tissue engineering applications especially for growth of
host tissue, bone re-growth.
Porous scaffold is required for the development
of artificial blood vessels or peripheral nerve growth.
Ideal pore sizes vary for different cells and tissues

Porous scaffolds can be manufactured with specific pore
size, porosity, surface-area-to-volume ratio and
crystallinity.
Porous controlled-release systems contain pores that
are large enough to enable diffusion of the drug.
Synthetic biodegradable polymers such as PGA,
PLGA are used as porous scaffolding materials.
A modern method for creating porous scaffolds
composed of nano- and microscale biodegradable fibers
by electro spinning is a latest development in this field.

PHYSIOCHEMICAL CHARACTERIZATION OF
SCAFFOLFDS
Polymeric scaffolds have evolved to serve not merely as
carriers of cells and inductive factors, but to actively
instruct cells and provide step by step guidance of tissue
formation.
Several characterizations are required for the
fabrication of successful 3D scaffolds. They are
(i) external geometry (e.g., macro-, microstructure,
interconnectivity),
(ii) surface properties (e.g., surface energy, chemistry,
charge, surface area),

(iii) porosity and pore size
(iv) interface adherence & biocompatibility
(v) degradation characterization (e.g., biodegradation),
(vi) mechanical competence (e.g., compressive and
tensile strength).
Developing scaffolds that mimic the architecture of
tissue at the nano scale is one of the most important
challenges in the field of tissue engineering.
Polymeric scaffolds how excellent potential with
mechanical properties and with wide range of
degradation, the qualities which are essential for a range
of tissue engineering applications

SURFACE AND MECHANICAL PROPERTIES
Surface properties include both chemical and
topographical characteristics, which can control and
affect cellular adhesion and proliferation.
scaffolds with a large and accessible surface area are
favorable.
The surface properties can be selectively modified to
enhance the performance of the biomaterials i.e by
altering the surface Functionality using thin film
deposition, the optimal surface, chemical, and physical
properties can be attained

The proper mechanical properties for a biomaterial to
be used in a tissue engineering application are critical
to the success of the implant.
The bio stability of many scaffolds depends on the
factors such as strength, elasticity, and absorption at the
material interface and its chemical degradation.
The scaffold should have proper mechanical
properties and degradation rate with the bioactive
surface to encourage the rapid regeneration of the
tissue.

conclusions
In summary, tissue engineering is one of the most
exciting interdisciplinary and multidisciplinary research
areas and is growing exponentially over time.
Scaffold materials and fabrication technologies play a
crucial role in tissue engineering.
All these techniques for scaffold fabrication are sensitive
to the various processing parameters.
Nanotechnology can provide strategies that can help to
create features on a scaffolds in a dimentional range
that may be adequate cells and biochemicals.

Aadrsh kumar tiwari bbau

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