Influence of Nanocarbons on Collagen Molecular Ordering and Fibril ...
Graduate Category: Engineering and Technology Degree Level: PhD Abstract ID# 598
Influence of Nanocarbons on Collagen Molecular Ordering and Fibril Alignment Emily C. Green, Yiying Zhang, Dilinazi Aishanjiang, Marilyn L. Minus ABSTRACT
MOLECULAR AND FIBRIL ALIGNMENT PRIOR TO ELONGATION
Due to the rigid-rod characteristics of carbon nanotubes (CNT) they have been shown to aide and induce atomic and nano-scale ordering of polymer materials. In this work, this CNT trait is exploited to understand its potential along with other rigid nano-carbons to promote ordered assembly of biological materials. For the synthetic formation of collagen materials, highly aligned collagen fibrils are necessary in order to replicate the native collagen structure. In this work collagen fibers were self-assembled in the presence of both single-wall carbon nanotubes (SWNT) and carbon nano-chips (CNC) using a gel-spinning approach. The morphology and dispersion quality of the nano-carbons was found to play a significant role in the overall collagen fibril alignment. X-ray scattering and microscopy analysis shows that low concentrations (i.e., 0.5 wt% loading) of well-dispersed SWNT promote collagen molecular and fibrillar alignment, as well as D-banding formation consistent with native collagen. Beyond ordering, the nano-carbons used were also able to reinforce the collagen composite fibers, which showed a considerable increase in both strength and elastic modulus (100% and 122%, respectively) as compared to control fibers. During post-processing or elongation of the fibers, the nano-carbons were capable of inducing higher levels of fibril alignment and packing as compared to control fibers. This work is the first to show direct evidence that nano-carbon fillers may promote collagen molecular and fibril alignment during both the self-assembly process as well as during the application of stress.
SAXS INTENSITY PATTERNS
D-BANDING STRUCTURE
PARALLELISM INDEX
Equatorial streak fibril alignment Meridional/Diffused scattering misalignment
C2
Banding is present in all fibers More prevalent in SWNT fibrils Inherent shape of nano-carbon may play a role in the development of banding 1-D SWNT have a positive influence on both fibril and molecular alignment. AFM ON SWNT GEL PI =
SWNT
CNC
𝐼𝑀𝑀𝑀 −𝐼𝑀𝑀𝑀 𝐼𝑀𝑀𝑀+𝐼𝑀𝑀𝑀
Good alignment and a high degree of anisotropy is observed for the 0.5 wt% SWNT composite fibers, while CNC are seen to hinder fibril alignment
MOTIVATION
STRAIN IMPACT ON FIBRIL ALIGNMENT
Nano-carbons have been shown to template polymer orientation and alignment.
SEM OF ELONGATED FIBERS
SAXS INTENSITY PATTERNS VS ELONGATION
PARALLELISM INDEX
MOLECULAR SPACING (WAXD)
GEL-SPINNING POLYMER TEMPLATING
During hot-drawing
In order to apply this templating effect to other systems, the processing conditions must be tailored.
Initial Morphology After hot-drawing
CNT
polymer
FLOW
This work utilizes a flow based gel-spinning approach to fabricate collagen fibers with high fibril alignment and strength. In addition, nano-carbons are incorporated into the fibers to investigate their ability to influence fibril alignment by acting as a rigid nano-scale template.
As-spun composite fibers show lower degrees of global alignment Increases in alignment for all fibers at 6% strain
INTRODUCTION Collagen is a bio-polymer that has received much attention over the last century due to its prevalence throughout the human body in all organs and tissues. For this reason understanding the structure and assembly of collagenous materials is a necessity. Of the numerous types of collagen, fibril-forming type I is the primary form present in bone, tendon, ligaments and connective tissue. Type I collagen self-assembles in vivo to form highly ordered fibers. Replicating this structure in vitro remains a challenge as the self-assembly process is not fully understood. How can nano-carbon help?
Ordering similar to polymer crystallization Molecular arrangement can be probed by X-ray Spectroscopy
APPLICATIONS: tissue repair and replacement nerve regeneration suture materials
MATERIALS & FIBER FORMATION METHOD from Advanced BioMatrix. Phosphate buffered saline (PBS), 1× and 10× solutions (1.37M Sodium Chloride, 0.027M Potassium Chloride, and 0.119M Phosphate Buffer, pH 7.3-7.5), 0.5N Sodium Hydroxide Solution (NaOH), and OmniPur® polyethylene glycol (PEG) (MW ~7000-9000) were purchased from Fisher Scientific. Super-purified SWNT (1.1 wt% Fe content, bulk density 0.14 g/cm3, lot #SP1001) were purchased from Continental Carbon Nanotechnologies, Inc. Carbon nanochips (CNC) (purity >99 wt% C; batch H700) were purchased from Catalytic Materials.
FIBER FORMATION:
SWNT (1-D)
SWNT/CNC
PureCol®
10× PBS
NaOH
Shaker
COLLAGEN GEL
1 μm
0.5 wt% SWNT Fiber
100 nm
**Ideally banding should occur at this stage
D: 1nm, L: ~1μm
CNC (2-D)
30 wt% PEG in 1× PBS
INCUBATION & WASHING
2 h (1× PBS)
18 h
0.5 wt% CNC Fiber
Collagen/SWNT fiber Collagen/CNC fiber
100 nm
T:
Influence of Nanocarbons on Collagen Molecular Ordering and Fibril Alignment Emily C. Green, Yiying Zhang, Dilinazi Aishanjiang, Marilyn L. Minus ABSTRACT
MOLECULAR AND FIBRIL ALIGNMENT PRIOR TO ELONGATION
Due to the rigid-rod characteristics of carbon nanotubes (CNT) they have been shown to aide and induce atomic and nano-scale ordering of polymer materials. In this work, this CNT trait is exploited to understand its potential along with other rigid nano-carbons to promote ordered assembly of biological materials. For the synthetic formation of collagen materials, highly aligned collagen fibrils are necessary in order to replicate the native collagen structure. In this work collagen fibers were self-assembled in the presence of both single-wall carbon nanotubes (SWNT) and carbon nano-chips (CNC) using a gel-spinning approach. The morphology and dispersion quality of the nano-carbons was found to play a significant role in the overall collagen fibril alignment. X-ray scattering and microscopy analysis shows that low concentrations (i.e., 0.5 wt% loading) of well-dispersed SWNT promote collagen molecular and fibrillar alignment, as well as D-banding formation consistent with native collagen. Beyond ordering, the nano-carbons used were also able to reinforce the collagen composite fibers, which showed a considerable increase in both strength and elastic modulus (100% and 122%, respectively) as compared to control fibers. During post-processing or elongation of the fibers, the nano-carbons were capable of inducing higher levels of fibril alignment and packing as compared to control fibers. This work is the first to show direct evidence that nano-carbon fillers may promote collagen molecular and fibril alignment during both the self-assembly process as well as during the application of stress.
SAXS INTENSITY PATTERNS
D-BANDING STRUCTURE
PARALLELISM INDEX
Equatorial streak fibril alignment Meridional/Diffused scattering misalignment
C2
Banding is present in all fibers More prevalent in SWNT fibrils Inherent shape of nano-carbon may play a role in the development of banding 1-D SWNT have a positive influence on both fibril and molecular alignment. AFM ON SWNT GEL PI =
SWNT
CNC
𝐼𝑀𝑀𝑀 −𝐼𝑀𝑀𝑀 𝐼𝑀𝑀𝑀+𝐼𝑀𝑀𝑀
Good alignment and a high degree of anisotropy is observed for the 0.5 wt% SWNT composite fibers, while CNC are seen to hinder fibril alignment
MOTIVATION
STRAIN IMPACT ON FIBRIL ALIGNMENT
Nano-carbons have been shown to template polymer orientation and alignment.
SEM OF ELONGATED FIBERS
SAXS INTENSITY PATTERNS VS ELONGATION
PARALLELISM INDEX
MOLECULAR SPACING (WAXD)
GEL-SPINNING POLYMER TEMPLATING
During hot-drawing
In order to apply this templating effect to other systems, the processing conditions must be tailored.
Initial Morphology After hot-drawing
CNT
polymer
FLOW
This work utilizes a flow based gel-spinning approach to fabricate collagen fibers with high fibril alignment and strength. In addition, nano-carbons are incorporated into the fibers to investigate their ability to influence fibril alignment by acting as a rigid nano-scale template.
As-spun composite fibers show lower degrees of global alignment Increases in alignment for all fibers at 6% strain
INTRODUCTION Collagen is a bio-polymer that has received much attention over the last century due to its prevalence throughout the human body in all organs and tissues. For this reason understanding the structure and assembly of collagenous materials is a necessity. Of the numerous types of collagen, fibril-forming type I is the primary form present in bone, tendon, ligaments and connective tissue. Type I collagen self-assembles in vivo to form highly ordered fibers. Replicating this structure in vitro remains a challenge as the self-assembly process is not fully understood. How can nano-carbon help?
Ordering similar to polymer crystallization Molecular arrangement can be probed by X-ray Spectroscopy
APPLICATIONS: tissue repair and replacement nerve regeneration suture materials
MATERIALS & FIBER FORMATION METHOD from Advanced BioMatrix. Phosphate buffered saline (PBS), 1× and 10× solutions (1.37M Sodium Chloride, 0.027M Potassium Chloride, and 0.119M Phosphate Buffer, pH 7.3-7.5), 0.5N Sodium Hydroxide Solution (NaOH), and OmniPur® polyethylene glycol (PEG) (MW ~7000-9000) were purchased from Fisher Scientific. Super-purified SWNT (1.1 wt% Fe content, bulk density 0.14 g/cm3, lot #SP1001) were purchased from Continental Carbon Nanotechnologies, Inc. Carbon nanochips (CNC) (purity >99 wt% C; batch H700) were purchased from Catalytic Materials.
FIBER FORMATION:
SWNT (1-D)
SWNT/CNC
PureCol®
10× PBS
NaOH
Shaker
COLLAGEN GEL
1 μm
0.5 wt% SWNT Fiber
100 nm
**Ideally banding should occur at this stage
D: 1nm, L: ~1μm
CNC (2-D)
30 wt% PEG in 1× PBS
INCUBATION & WASHING
2 h (1× PBS)
18 h
0.5 wt% CNC Fiber
Collagen/SWNT fiber Collagen/CNC fiber
100 nm
T:
