Syntheric polymer
Biopolymer
Biocompatibility
Biocompatibility
Definition: the ability of a material to perform with an appropriate host response in a specific application (Williams 1987)
Monomers & Additives: Many polymers themselves are inert, but unreacted monomers (e.g., styrene, bisphenol A) or additives (plasticizers, flame retardants, stabilizers, pigments) can leach out and cause toxicity.
Degradation Products: Heat, UV, or mechanical stress can break polymers into smaller molecules or nanoparticles that may be harmful.
Nanoplastics & Microplastics: Increasing concern that very small polymer fragments can accumulate in living organisms and ecosystems.
Health Effects
Category | ISO Standard (10993 series) | ASTM Standard (F-series & others) | Notes / Applications |
Framework / General Guidance | ISO 10993-1 – Risk management process for biological evaluation | ASTM F748 – Guide for selecting biological tests for polymers | ISO sets the strategy; ASTM helps choose appropriate tests |
Cytotoxicity (in vitro) | ISO 10993-5 – Tests for in vitro cytotoxicity | ASTM F981 – Cytotoxicity, sensitization, systemic toxicity for polymers | Used for screening polymer extracts on cultured cells |
Irritation & Sensitization | ISO 10993-10 – Tests for irritation and skin sensitization | ASTM F763 – Short-term screening for irritation & toxicity of polymers | Both evaluate dermal/mucosal compatibility |
Systemic Toxicity | ISO 10993-11 – Acute, subchronic, chronic systemic toxicity | ASTM F981 – Systemic toxicity evaluation for implant polymers | Long-term safety, especially for implantable polymers |
Degradation / Leachables | ISO 10993-13/14/15 – Evaluation of degradation products of polymers, ceramics, metals | ASTM F619 – Extraction & analysis of leachables from polymers | Critical for resorbable sutures, drug delivery systems |
Chemical Characterization | ISO 10993-18 – Identification & quantification of extractables | ASTM F719 – Tests for extractables of polymers | Basis for toxicological risk assessment |
Toxicological Risk Assessment | ISO 10993-17 – Allowable limits for leachables & degradation products | — | ISO provides a framework; ASTM methods can support analysis |
Accelerated Aging | — | ASTM F1980 – Accelerated aging for polymer-based devices | Determines shelf-life & stability of medical polymers |
Material-Specific Standards | — | ASTM F2026 – Standard specification for PEEK polymers in surgical implants | Material-focused ASTM standards complement ISO’s general framework |
Antibacteria
Tissue / Organ | Young’s Modulus (Stiffness, E) | Tensile / Compressive Strength | Notes |
Skin | 0.42 – 0.85 MPa (varies by layer & hydration) | Tensile strength ≈ 5–30 MPa | Highly elastic, anisotropic; stronger along collagen fiber directions |
Cartilage (articular) | 0.1 – 2 MPa | Compressive strength ≈ 5–25 MPa | Viscoelastic; absorbs impact in joints |
Tendon / Ligament | 0.2 – 1 GPa | Tensile strength ≈ 50–150 MPa | Very strong in tension, aligned collagen fibers |
Bone (cortical) | 10 – 30 GPa | Tensile ≈ 100–150 MPa, Compressive ≈ 100–200 MPa | Load-bearing, stiffest natural tissue |
Bone (trabecular) | 0.05 – 0.5 GPa | Compressive ≈ 2–12 MPa | Porous, lightweight |
Blood vessels (arteries) | 0.1 – 1 MPa | Tensile strength ≈ 1–3 MPa | High elasticity, cyclic fatigue resistance |
Heart muscle (myocardium) | ~20 – 500 kPa | — | Very soft, contracts actively; anisotropic |
Liver | ~0.5 – 0.8 kPa | — | Very soft organ, sensitive to stress |
Brain | 0.1 – 1 kPa | — | One of the softest human tissues |
Mechanical strength
Biomaterial Class | Young’s Modulus (E) | Strength | Biomedical Applications |
Metals (Ti alloys, stainless steel, Co-Cr) | 100 – 200 GPa | Tensile ≈ 500–1200 MPa | Bone plates, stents, dental & orthopedic implants |
Ceramics (alumina, zirconia, hydroxyapatite) | 50 – 400 GPa | Compressive ≈ 1000–2000 MPa, brittle | Dental crowns, bone grafts, joint coatings |
Polymers (medical grade) | 0.1 – 3 GPa | Tensile ≈ 50–100 MPa | Sutures, catheters, drug delivery systems |
Elastomers (e.g., silicone, polyurethane) | 0.5 – 10 MPa | Tensile ≈ 5–50 MPa | Soft tissue implants, pacemaker leads |
Composites (fiber-reinforced, bio-ceramic/polymer) | Tunable (1 – 30 GPa typical) | 50–500 MPa | Bone plates, dental fillings, scaffolds |
Bioresorbable polymers (PLA, PGA, PCL) | 0.1 – 3 GPa | 50–100 MPa | Sutures, resorbable stents, tissue scaffolds |
1. Key Factors in Cell–Biomaterial Interaction
Cells sense and respond to biomaterials through:
Cell response
Adhesion: Mediated by integrins binding to adsorbed proteins (fibronectin, vitronectin, collagen).
Proliferation & viability: Depends on surface energy, chemistry, and nutrient permeability.
Differentiation: Stem cells can be directed by stiffness, chemical signals, and topography.
Migration: Guided by surface patterns or gradients (haptotaxis, durotaxis).
Immune response: Macrophages and fibroblasts sense “foreignness”; may lead to fibrosis or foreign body reaction.
Type | Mechanism | Examples |
Physical | Contact with surface topography, stiffness | Neurons aligned along microgrooves; stem cells sensing substrate stiffness |
Chemical | Interaction with functional groups, charges, or released ions | Calcium release from bioactive glass → bone regeneration |
Biological | Adsorbed proteins, tethered ligands, signaling molecules | RGD-modified hydrogels promoting cell adhesion |
Slipery surface for antibacteria