Biomaterials

❖Introduction
❖History & Evolution
❖Applications
❖Materials Used
❖Properties of effective Biomaterials
❖Natural source of Biomaterials
❖Synthetic sources of Biomaterials
❖Comparative Study between Natural and Synthetic Biomaterials
 Introduction
▪ term "biomaterials" emerged in the 1970s
▪ make devices to replace a part or a function of the body
▪ safe, reliably economically, and physiologically acceptable
▪ should not give off anything from its mass unless it is specifically engineered to do so
▪ interaction between biomaterials and the body is dynamic (short-term/long-term responses)
▪ Material used- natural (silk) or synthetic (ceramic)
▪ classified as biological, biomimetic, bio-based, and biomaterials
Uses
Application Examples
Replacement of diseased and Artificial hip joint, kidney
damaged part dialysis machine
Material Assist in healing Sutures, bone plates and screws
Science
Improve function Cardiac pacemaker, intra-ocular
lens
Correct functional abnormalities Cardiac pacemaker
Clinical Cell
Science Biology Correct cosmetic problem Chin augmentation
Aid to diagnosis Catheters
Fields required to develop biomaterials
Aid to treatment Drains
Historically, the selection of
material was based on -
✓ availability
✓ ingenuity of the individual
making & applying the
prosthetic

An artificial heart (device), Paris,1881

Developed by Étienne-Jules Marey
Evolution of Biomaterial Applications

Hip Replacement Prosthesis

 Materials for use Selection of biomedical
Materials Advantages Disadvantages Examples material
Polymers (nylon, Resilient Easy to Not strong Blood vessels,
silicon Rubber, Fabricate Deforms with time Sutures, ear, nose, Sequence
polyester, PTFE, May degrade Soft tissues ✓ Analysis of the problem;
etc) ✓ Consideration of
Metals (Ti and its Strong Tough May corrode, Joint replacement, requirement
alloys Co-Cr ductile dense, Difficult to Bone plates and ✓ Consideration of available
alloys, stainless make Screws, dental material and their properties
Steels) root Implant,
pacer, and suture Factors Considered
Ceramics Very Difficult to make Dental coating • A proper specification of the
(Aluminum Oxide, biocompatible Brittle Not Orthopedic desired function for the material
calcium Inert strong in resilient implants Femoral • An accurate characterization of
phosphates, compression head of hip the environment in which it must
including
function, and the effects that
hydroxyapatite
environment will have on the
carbon)
properties of the material
Composites Very Difficult to make Joint implants • A delineation of the length of time
(Carbon-carbon, biocompatible Heart valves the material must function
wire Or fiber Inert strong in • A clear understanding of what is
reinforced Bone compression meant by safe for human use.
cement)
Properties of Effective Biomaterial Material Evaluation
• Standard specifications-(a) the testing of certain products,
(b) the method of calculating the results
(c) the minimum permissible result,
• Laboratory Evaluation-indicate the suitability of certain
materials
• Clinical Trials
Natural Sources of Biomaterials for Scaffold
Traditional biomaterials used in
biomedicine-
❑ gelatine
❑ silk
❑ collagen

Why natural options?

✓ chemical stability,
✓ structural versatility,
✓ biocompatibility,
✓ high availability
✓ can form non-cytotoxic
hydrogels
✓ recapitulate natural tissue
properties
✓ therapeutic potential
✓ promote cellular adhesion
✓ innate cell recognition
Summary of the different protein and polysaccharide-based biomaterials
Material Source Structures
Collagen Natural ECM or Scaffolds
recombinant Sponges
Hydrogels
Films/membranes
Bioinks
Gelatin Bovine or porcine Microparticles
collagen
Collagen Scaffold
Silk Butterflies/moths, Film, woven mesh
spiders
or recombinant
Cellulose Plants, bacteria Nanofibres
Gels
Nanocrystals
Alginate Brown Algae Hydrogels
Sponges
Films
Microparticles
Alginate Hydrogel Beads
Classification
 Synthetic Sources of Biomaterials
Properties of Synthetic Biomaterials
•Controllable mechanical strength tailored to match
specific tissue requirements
•Tunable degradation rates optimized for tissue
regeneration timelines
•Customizable chemical composition allows
incorporation of bioactive molecules
•Reproducibility ensures consistent performance across
batches
Fabrication Methods of Synthetic Biomaterials
1.Electrospinning creates fibrous scaffolds mimicking ECM
structure
2.3D printing allows complex geometries for patient-specific
implants
3.Solvent casting/particulate leaching produces porous
structures with controlled pore size
4.Gas foaming creates highly porous scaffolds with
interconnected pores

Metal orthodontic braces Bio-prostetic heart valves

Comparative Study between Natural & Synthetic Biomaterials
 Biomaterials for Regenerative Medicine
Biocompatibility Tissue Engineering Biomaterials
ability of a material to perform with an ✓ biocompatibility,
appropriate host response in a specific situation ✓ bioactivity,
Factors examined for Biomaterials – ✓ biodegradability,
▪ Toxicity ✓ tailorable physical & mechanical properties
▪ Biocompatibility
▪ Mechanism of immune responses
Classes of Biomaterials-
A. Bio-inert-e.g. make direct interaction with
the neighbouring bone tissue, however,
no chemical reactions occur between
them
B. Bio-active-e.g. make some chemical
bonds with bone tissue, identified as
osseointegration
C. Bio-tolerant- e.g. disconnected from bone
Scaffold for Tissue Engineering
through a fibrous layer
 Scaffold for Tissue Engineering
Work?
✓ 3D, porous biomaterial structures
✓ provide a framework for cells to attach, grow,
and differentiate, favours new tissue
formation
✓ mimic the natural ECM & can be made from
natural or synthetic materials

Features
➢ Porous Structure: transport of nutrients,
oxygen, and waste products, essential for cell
survival & growth.
➢ Biocompatibile
➢ Biodegradability: new tissue is formed, leaving
behind the newly formed tissue
➢ Mechanical Properties: mechanical properties
that match the tissue they are intended to replace
 How Scaffolds Work? Applications of Scaffolds
✓ Cell Seeding: Cells are seeded onto the scaffold, • Bone Tissue : repair bone defects and promote
where they can attach and proliferate bone regeneration.
✓ Tissue Formation: provides a 3D environment • Cartilage Tissue :to repair damaged cartilage and
that supports cell growth and differentiation, promote cartilage regeneration.
leading to the formation of new tissue • Skin Tissue : to repair skin wounds and promote
✓ Scaffold Degradation: As the new tissue skin regeneration.
matures, the scaffold degrades, leaving behind • Other Applications: explored for the
the newly formed tissue regeneration of other tissues, such as blood
vessels, nerves, and muscle
 3D Printer and Printing
fabricate scaffolds and devices for tissue engineering
applications
Advantages-
a) patient-specific designs
b) high structural complexity
c) rapid on-demand fabrication
d) low-cost
e) Design flexibility
Applications-
❖ craniofacial implants
❖ dental molds, crowns and implants
❖ prosthetic parts
❖ on-demand medical equipment
❖ surgical models
❖ tissue regeneration such as skin and bone, organ
printing, and tissue models for drug discovery
 Common stages of the 3D printing process to develop tissue-mimetic devices

➢ 3D computer assisted design (CAD) model is Limitations-

developed ✓ lack of diversity in “biomaterial inks”
➢ Digitally sliced images that consist of text-based ✓ Processing speed
command lists, including ink parameters and ✓ Printing speed
printing directions, are generated ✓ Printing resolution
➢ A 3D printer generates the tissue mimetic
construct
Properties of Printable Biomaterials
✓ be printable
✓ be biocompatible
✓ have appropriate mechanical properties
✓ have good degradation kinetics
✓ form safe degradation byproducts
✓ exhibit tissue biomimicry

Schematics depicting 3D printing techniques

3D Printing of Cytocompatible 3D printing of ceramic-based scaffolds
Graphene/Alginate Scaffolds for Mimetic for bone tissue engineering
Tissue Constructs
 INKS: 3D PRINTABLE BIOMATERIALS

Polymeric Biomaterial Inks

➢ ease of processability
➢ low cost
➢ biocompatibility
➢ degradation
➢ Mechanics
➢ Polymers used-
❖ Poly(lactic acid)
a) nontoxicity,
b) renewable feedstocks
c) easy processability
d) melt temperature around 175 °C 3D printed constructs from hard (left) to soft (right) in
❖ Poly(D,L-lactide) nature
✓ Application-bone fixation devices
✓ High mechanical strength
➢ Other polymers used- Acrylonitrile
Butadiene Styrene (ABS)
Poly(butylene terephthalate)
Hydrogel Inks Hydrogel
Properties ❖ 3D polymer networks with the ability to hold a
1) flow under modest pressures large quantity of water
2) gel quickly ❖ provide perfect “soft material” systems to mimic
3) maintain sufficient integrity native ECM microenvironments due to their
after build up tunable mechanics, degradation and
functionalizability
 ▪ solution (3%),
▪ remained as a solution below
15 °C,
▪ gelled at 37 °C within 30 min

Fabrication of 3D constructs from ECM based bioinks