BME 320 Midterm 1: Biomaterials

Biomaterial

material intended to interface w/ biological systems to evaluate, treat, augment, or replace any tissue, organ, or function of the body

Biomaterials science

physical & biological study of materials & their interaction w/ the biological environmentin order to develop and improve biomaterials for medical applications

Biocompatibility

ability of a biomaterial to be tolerated by the body & coexist w/ cells, tissues, & organs w/ out causing any adverse reaction or toxicity; no formal definition

Bioinert

material that serves a purely physical and/or mechanical function but otherwise does not influence cell or tissue behavior

Bioactivity

ability of a material to actively stimulate or influence cell & tissue behavior; alters cellular gene expression (e.g. cell proliferation, migration, & differentiation)

Bioresorbable

ability of a material to reabsorb (i.e. dissolve, degrade, erode) over time after implantation in the body

1st gen biomaterial definition

used to replace a body part w/ an artificial one w/ similar physical and/or mechanical properties; made from bioinert materials

1st gen biomaterials device examples

hip & knee prosthetics

1st gen biomaterials material examples

titanium-based alloy (metal), alumina (ceramic), PMMA (polymer), silione

2nd gen biomaterials definition

biomaterials that are bioactive OR bioresorbable

2nd gen biomaterials example/materials

• sutures made from PLGA (poly lactic-co-glycolic acid)

• ceramic acetabular cup implants made from hydroxyapatite

• implants w/ textured surfaces

3rd gen biomaterials definition

biomaterials that are bioactive AND bioresorbable, designed to stimulate healing; bioactive through release of ions, bioactive signals, cytokines, drugs etc. and/or through biomaterial structure & chemical characteristics

3rd generation biomaterials examples/materials

• decellularized tissue ECMs retain bioactive factors & proteins

• chirality of peptides leads to regenerative immune response

• bone filler used to stimulate cell growth in non-load bearing regions

• bioglass

4th generation biomaterial definition

biomaterials that can mimic native tissue functionality

4th generation biomaterial exampes/materials

• bio-fabricated tissues & the hydrogels used to grow organoids

• micro/nano-scale particles that can perform targeted delivery of bioactive molecule into specific cells

• smart, stimuli-responsive biomaterials that can release a drug (e.g. insulin) in response to elevated glucose levels

• cancer vaccines to reprogram the host immune system against tumor cells

4 classes of materials

metals, ceramics, polymers, composites

modifying and engineering material properties

composition, processing, structure, design

examples of metal applications of biomaterials

hip implant, knee implant, orthodontics, heart valves, spine (inter-vertebral implants), stents

metals used as main components of biomaterials

magnesium, titanium, iron, aluminum, gold

metals used as additives in biomaterials

calcium, manganese, cobalt, nickel, copper, silver, platinum, zirconium

applications of metal implants/biomaterials

load bearing, long-term performance, resistance to deformation, strength, fatigue resistance, & capable of being shaped into different designs

atomic structure of metals

• crystalline solids, mostly polycrystalline

• held together by metallic (covalent) bonds, high density

• arranged in orderly, repeating patterns make up crystal lattice

unit cell

motif that repeats itself throughout crystal

body centered cubic

tungsten, iron, molybdenum

1 atom in center, rest are 1/8 (8 atoms on corners)

face centered cubic

aluminum, copper, gold

8 corner atoms are 1/8 and 6 atoms on faces are 1/2

hexagonal close packed

3 atoms in middle are 1, top and bottom are 1/2, 12 on corners of hexagon are 1/6 each

microstructure of metals

• grains form as metals solidify

• as molten metal cools, atoms organize into crystal structures