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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
