Biomaterials Lab Quiz 1: Surface Wettability

Course Information

• Course Title: Biomaterials
• Course Number: ENGR-UH 4810
• Professor: Jeremy Teo
• Instructor: Shafiya Sabah
• Semester: Fall 2024

Lab Information

• Biomaterials lab: 30% of total grade
• Lab Report: 10%
• Lab Quiz 1: 10%
• Lab Quiz 2: 10%

Requirements

• Complete mandatory online safety training

Lab Safety

• Personal Protective Equipment (PPE):
  • Laboratory coats
  • Protective gloves
  • Safety goggles
  • Long pants
  • Closed toe shoes

Hazard Symbols

• Corrosive chemical
• Skin and Eye irritant
• Flammable
• Biohazard sign
• Toxic
• Harmful to environment
• Health hazard (Carcinogen - Organ Toxicity)
• Explosive

Lab 1: Surface Wettability Characterization

Biomaterial surface wettability

• Biomaterial: Any substance (natural or synthetic) used in the body for treatment, support, or replacement of tissues/organs/body functions. Biocompatibility measures how well it integrates with a biological system.
• Wettability: Ease with which a fluid spreads across a solid surface
• Hydrophilic surfaces: Water spreads out on these surfaces.
• Hydrophobic surfaces: Water forms droplets/beads on these surfaces.
• Surface characteristics (wettability, topography, and surface energy), influence biocompatibility.
• Wettability of biomaterials affects protein adsorption and cellular response.  Cells adhere better to moderate wettable surfaces.

Surface modification techniques

• Surface treatments alter surface composition using physical/chemical reactions.
• An ideal treatment is thin (minimizes effects on bulk properties), resistant to delamination, and simple/robust (promotes commercialization).

Water Contact Angle

• Contact angle measurements evaluate biomaterial wettability in vitro
• A liquid drop on a solid surface forms an angle at the intersection of liquid, vapor, and solid boundaries.
• Young's Equation: Y_sv - Y_sl - Y_lv cosθ = 0
  • Y_LV: Surface tension of the liquid
  • Y_SL: Solid-liquid interfacial tension
  • Y_SV: Surface energy of the solid
  • θ: Contact angle
• High contact angle = low wettability (hydrophobic)
• Low contact angle = high wettability (hydrophilic)

Contact Angle Measuring Equipment

• Drop shape analyzer (Krüss DSA25S) includes:
  • Illumination
  • Dosing unit
  • Lens
  • Camera
  • Sample stage

PDMS (Polydimethylsiloxane)

• Clear, non-toxic silicone (hydrophobic) polymer
• Excellent biocompatibility, thermal stability, and flexibility.
• Widely used in microfluidic chips, biosensors, and drug delivery carriers.

APTES (3-Aminopropyl)triethoxysilane

• Silane reagent chemically modifies material surfaces.
• Creates a durable, functional layer introducing chemical groups (e.g., amines) increasing hydrophilicity.

Plasma Treatment

• Physical surface modification technique improving wettability.
• Gas/mixture of gases in a sealed, low-pressure vacuum chamber.
• RF (radio frequency) power energizes the gases.
• A purplish glow indicates plasma generation.
• Activated ions vibrate cleaning contaminants from the surface.

Test your understanding of surface wettability characterization in biomaterials. This quiz focuses on the properties and safety precautions necessary for handling various biomaterials in a laboratory setting. Ensure you are familiar with the types of PPE and hazard symbols relevant to lab safety.