Biomaterial Final Exam - CH 11-16

Types of Natural Biodegradable Polymers used for Medical applications

Fibrin, Collagen, Chitosan, Gelatin, Hyaluronan

Types of Synthetic Biodegradable Polymers used for Medical applications

PLA, PGA, PLGA, PCL

4 steps of Degradation

Water Sorption, Reduction of Mechanical Properties, Reduction of Molar Mass, Weight Loss

3 Types of Molding Fabrication Techniques

Compression molding, Melt molding, and Solvent Casting

Melt Molding Pros and Cons

Pros: Uniform drug distribution, Wide range of shapes

Cons: Thermal drug instability, Cos

Solvent Casting Pros and Cons

Pros: Simplicity, Room temperature operations, suitable for heat sensitive drugs

Cons: Possible Non-uniform drug distribution, Fragile, Unwanted matrix porosity

Hydrogel Definitions

Water Insoluble.

3D network of polymeric chains.

Cross-linked by chemical or physical bonding.

Capable of swelling substantially in aqueous conditions.

Polymer network in which water is dispersed throughout the structure

How is the degree of Hydrogel swelling quantified?

Ratio of sample volume in the swollen state to volume in the dry state.

Weight degree of swelling: ratio of weight to dry state

Why is the degree of Hydrogel swelling important

Solute diffusion coefficient through the hydrogel.

Surface properties and surface mobility.

Optical properties

Mechanical properties

2 types of dried Hydrogels

Aerogel and Xerogel

Features of Hydrogels

Large volumetric changes.

Hydrophilic

Highly Polyionic polymers

Structural Strength

Examples of Hydrogels

Jello

DNA/RNA

Blood Clot

pHEMA (soft contact lens)

Applications of Hydrogels

Drug Delivery

Surface modification

Biosensors

Soft contact lens

What is a Biosensor?

A device used to measure biologically-derived signals

What are the 3 components of a Biosensor

Sensitive biological element-receptor

Transducer

Signal Processors

What is a transducer

An interface that measures the physical change that occurs with the reaction at the bioreceptor then transforms that energy into measurable electrical outputs.

3 types of Transducers

Electrochemical.

Photochemical

Piezoelectric

Types of Detection elements

Physical Entrapment

Adsorption

Covalent Binding

Types of Advanced Wearable biosensors

Glasses

Mouthguards

Contact lenses

3 Main wear mechanisms

Adhesive

Abrasive

Third-Party

3 Main types of wear testing

Ball-on-Disc

Pin-on-Disc

Block-on-Disc

What is the Tissue Engineering Triad

Cells

Biomaterials

Growth Factors

4 main functions/features of the scaffold to engineer to be like ECM

Architecture

Cyto- and tissue compatibility

Bioactivity

Mechanical Property

Function and Features of Architecture

Provide void volume for vascularization

Facilitate host tissue integration

Degradable upon implantation

Functions and Features of Cyto- and Tissue compatibility

Support for cells to attach, grow, and differentiate

During in vitro culture and implantation

Compatible with cellular components of engineered tissues and cells in host tissue

Functions and Features of Bioactivity

Interact with cellular components of engineered tissues to facilitate and regulate activities

Functions and Features of Mechanical property

Provides mechanical and shape stability to tissue defects

4 major types of tissue engineering scaffolding approaches

Pre-made porous scaffold

Decellularized ECM

Cell sheets with secreted ECM

Cell encapsulated in self-assembled hydrogel

Pros and cons of Pre-made Porous Scaffolds

Pros: Most diversified choice, precise designs on architecture, easily engineered, load bearing tissues.

Cons: Inefficient, Limited penetration ability, Inhomogeneous cell distribution, Heterogenous properties in engineered tissues.

Oldest form of body modification

Ear piercing, seen in Persepolis in ancient Persia

Hypoallogenic

Very Low in nickel

Low allergy reaction

Types of hypoallogenic materials

Niobium

Titanium

Stainless Steel

Gold

Oldest known Tattoo

Otzi the Iceman in 3,250 BC

What type of leaves are used for Henna

Green leaves of Lawsonia inermis

What is used for Black Henna

p-phenylenediamine (PPD)

Body modification complications

Allergies

Infection

Slow wound healing

Rejection

What do Cochlear implants do?

Provides sense of sound to a person who is profoundly deaf or severely hard of hearing

Earliest age one can become eligible for Cochlear implants

FDA-approved beginning at 12 months of age

External parts of a Cochlear implant

Microphone

Speech processor

Transmitter

Internal parts of a Cochlear implant

Receiver

Electrode array

What do Cochlear implants do

Bypass damaged portions of the ear

Directly stimulates the auditory nerve

What do hearing aids do

Amplify sounds

For damaged ears