Rheology of Binary Colloidal Structures Assembled via Specific Biological Cross-Linking
详细信息 查看全文
- 作者：Amy L. Hiddessen ; David A. Weitz ; and Daniel A. Hammer
- 刊名：Langmuir
- 出版年：2004
- 出版时间：August 3, 2004
- 年：2004
- 卷：20
- 期：16
- 页码：6788 - 6795
- 全文大小：445K
- 年卷期：v.20,no.16(August 3, 2004)
- ISSN：1520-5827
文摘
The selectivity and range of energies offered by specific biological interactions serve as valuable toolsfor engineering the assembly of colloidal particles into novel materials. In this investigation, high affinitybiological interactions between biotin-coated "A" particles (RA = 0.475 
m) and streptavidin-coated "B"particles (RB = 2.75 m) drive the self-assembly of a series of binary colloidal structures, from colloidalmicelles (a large B particle coated by smaller A particles) to elongated chain microstructures (alternatingA and B particles), as the relative number of small (A) to large (B) particles (2 
le.gif"> NA/NB le.gif"> 200) is decreasedat a low total volume fraction (10-4 le.gif"> 
le.gif"> 10-3). At a significantly higher total volume fraction ( 
10-1)and a low number ratio (NA/NB = 2), the rheological behavior of volume-filling particle networks connectedby streptavidin-biotin bonds is characterized. The apparent viscosity (
) as a function of the shear rate(
), measured for networks at T = 0.1 and 0.2, exhibits shear-rate-dependent flow behavior, and both theapparent viscosity and the extent of shear thinning increase upon an increase of a factor of 2 in the totalvolume fraction. Micrographs taken before and after shearing show a structural breakdown of the flocculatedbinary particle network into smaller flocs, and ultimately a fluidlike suspension, with increasing shearrate. Rheological measurements provide further proof that suspension microstructure is governed byspecific biomolecular interactions, as control experiments in which the streptavidin molecules on particleswere blocked displayed Newtonian flow behavior. This investigation represents the first attempt at measuringthe rheology of colloidal suspensions where assembly is driven by biomolecular cross-linking.
m) and streptavidin-coated "B"particles (RB = 2.75 m) drive the self-assembly of a series of binary colloidal structures, from colloidalmicelles (a large B particle coated by smaller A particles) to elongated chain microstructures (alternatingA and B particles), as the relative number of small (A) to large (B) particles (2 le.gif"> NA/NB le.gif"> 200) is decreasedat a low total volume fraction (10-4 le.gif"> le.gif"> 10-3). At a significantly higher total volume fraction ( 10-1)and a low number ratio (NA/NB = 2), the rheological behavior of volume-filling particle networks connectedby streptavidin-biotin bonds is characterized. The apparent viscosity () as a function of the shear rate(), measured for networks at T = 0.1 and 0.2, exhibits shear-rate-dependent flow behavior, and both theapparent viscosity and the extent of shear thinning increase upon an increase of a factor of 2 in the totalvolume fraction. Micrographs taken before and after shearing show a structural breakdown of the flocculatedbinary particle network into smaller flocs, and ultimately a fluidlike suspension, with increasing shearrate. Rheological measurements provide further proof that suspension microstructure is governed byspecific biomolecular interactions, as control experiments in which the streptavidin molecules on particleswere blocked displayed Newtonian flow behavior. This investigation represents the first attempt at measuringthe rheology of colloidal suspensions where assembly is driven by biomolecular cross-linking.