The document summarizes the work done at the Liu Nanobionics Lab, which focuses on biomaterials, tissue engineering, and nanotechnology. The lab studies how biomaterials interact with biological systems, develops tissue engineering approaches using scaffolds and growth factors, and modifies material surfaces at the nano-scale to enhance biocompatibility. It also explores techniques like 3D printing and electrospinning to control scaffold architecture for tissue regeneration applications.

1. Liu Nanobionics Lab
Biomaterials
Tissue Engineering
Nanotechnology

2. Biomaterials
 Biomaterials encompasses aspects of
medicine, biology, chemistry,
engineering and materials science.
 Biomaterials are : “Non-viable
materials used in a medical devices
intended to interact with biological
systems” [D.F. Williams, 1987]

3. Human Tissue Damage
 Disease (e.g cancer, infection, degenerative
diseaes).
 Trauma (e.g accidental, surgery).
 Congenital abnormalities (e.g birth defects).
 Current clinical treatment based on:
Grafts and Transplants
Artificial Biomaterials

4.  Tissue loss as a result of injury or
disease, in an increasing ageing
population, provides reduced quality
of life for many at significant
socioeconomic cost.
 Thus a shift is needed from tissue
replacement to tissue regeneration by
stimulation the body’s natural
regenerative mechanisms.

5. Biomaterials: Examples
 Joint replacements
 Bone plates
 Bone cement
 Hip Joint
 Artificial ligaments
and tendons
 Dental implants for Heart valve Hip joint
tooth fixation
 Blood vessel
prostheses
 Heart valves
 Skin repair devices
 Cochlear
replacements Knee joint Skin
 Contact lenses

6. Biomaterials
 Prostheses have significantly
improved the quality of life for
many ( Joint replacement, Cartilage
meniscal repair, Large diameter
blood vessels, dental)
 However, incompatibility due to
elastic mismatch leads to
biomaterials failure.

7. Tissue Engineering
 National Science Foundation first defined
tissue engineering in 1987 as “ an
interdisciplinary field that applies the
principles of engineering and the life
sciences towards the development of
biological substitutes that restore,
maintain or improve tissue function”

8. Tissue engineering
 Potential advantages:
unlimited supply
no rejection issues
cost-effective

9. Tissue Engineering
Expand number in culture
Remove cells from the
body.
Seed onto an appropriate
scaffold with suitable growth
factors and cytokines
Re-implant engineered
tissue repair damaged
site
Place into culture

10.  SCAFFOLDS

11. Synthetic polymers
 More controllable from a
compositional and materials
processing viewpoint.
 Scaffold architecture are widely
recognized as important parameters
when designing a scaffold
 They may not be recognized by cells
due to the absence of biological
signals.

12. Natural polymers
 Natural materials are readily
recognized by cells.
 Interactions between cells and
biological materials are catalysts to
many critical functions in tissues
 These materials have poor
mechanical properties.

19. Tissue engineering scaffold:
Self-assembly
 Self-aggregation of
hydrophilic, lipophilic
groups
 First layer creates
template for growth of
second layer
 Ions can be deposited on
charged sites
 This kind of self-
aggregation leads to
ordered, heirarchical
structures

20. Supramolecular Chemistry
http://www.chm.bris.ac.uk/webprojects2003/lee/supra1.jpg

21. Tissue engineering scaffold:
controlled architecture
Featured with:
Pre-defined channels;
with highly porous
structured matrix;
With suitable chemistry
for tissue growth –
Collagen or HA
No toxic solvent involved,
it offers a strong potential
to integrate cells/growth
factors with the scaffold
fabrication process.

22. Architecture of Hard Tissue
 Staggered mineral platelets
(hydroxyapataite) embedded in a
collagen matrix
 Arrangement of platelets in
preferred orientations makes
biocomposites intrinsically
anisotropic
 Under an applied tensile stress,
the mineral platelets carry most
of the tensile load
 Protein matrix transfers the load
between mineral crystals via
shear
 Biocomposites can be described
through tension-shear model
described by Ji et. al.

23. Tissue engineering scaffold:
Electrospinning
 This process involves the ejection of a charged polymer fluid onto an oppositely
charged surface.
 Multiple polymers can be combined
 Control over fiber diameter and scaffold architecture

24. Printing Techniques for Tissue Engineering

25. Techniques to study scaffolds:
Scanning Probe Microscopy
 Atomic Force
Microscopy :Surface
irregularities
 Scanning Tunneling
Microscopy:
Conducting Surfaces
 Adhesion Force
Microscopy:
Functionalised tips

26. Surface Modification of Biomaterials

27. Enhanced intrinsic biomechanical properties of osteoblastic
mineralized tissue on roughened titanium surface
 Nano-indentation
 Acid-etched vs. Machined
surfaces
 culturing osteoblasts on
rougher titanium surfaces
enhances hardness and
elastic modulus of the
mineralized tissue

28. Surface modification of SPU
 Segmented Polyurethane
– common biocompatible
elastomer
 2-methacryloyloxyethyl
phosphorylcholine added
to create nano-domains
on surface
 Nano-scale domains
reduce platelet adhesion
to biomaterial surface
Nano-scale surface modification of a segmented polyurethane with a phospholipid polymer, Biomaterials 25 (2004) 5353–5361

29. Protecting Bionic Implants

30. Immunoisolation for Cell-encapsulation
therapy
 Liver Dysfunction: Encapsulation of
Hepatic Cells
 Pancreas Dysfunction: Encapsulation of
Islets of Langerham
 Disorders of the CNS: Parkinson’s,
Alzheimer’s
 Pre-requisites for cell encapsulation
 continued and optimal tissue/cell
supply
 maintenance of cell viability and
function
 successful prevention of immune
rejection
 Nanoporous Silicone-based biocapsules
serves as Artificial Pancreas(Desai et
al. 2001)
 What are the drawbacks of such an
artificial pancreas?

31. Nanoengineering Bio-analogous
Structures
 Bone-cartilage
composite ?
 Muscle ?
 Brain-machine
Interface ?

32. An Ink-Jet Printer for Tissue Engineering?