Synthesis of Layered, Graded Bioscaffolds - Structural Interfaces and Attachments in Biology - page 344

Fig. 16.2 Schematic of liquid phase co-synthesis scheme. Type II collagen-GAG (CG) suspen-
sion ( blue ) is carefully layered on top of collagen-GAG-CaP (CGCaP) suspension ( tan ) and
allowed to interdiffuse. Interdiffusion followed by freeze-drying creates a gradient interface
between the two compartments that mimics the physiology of natural articular joints.

(Reproduced, with permission, from Harley et al. [ 47 ])

CG structure to distinct cells or populations of cells. While it is possible to mechani-
cally separate the multi-compartment scaffold and perform analysis on individual
compartments, methods that enable simultaneous analysis of discrete regions from
within a single gradient or multi-compartment scaffold are especially useful.
Scaffold composition can be assessed by a number of analytical tools, notably
dimethylmethylene blue (DMMB) assay to determine GAG content, hydroxypro-
line assay to determine collagen content, and mass subtraction to determine CaP
content [ 40 ]. Further, CaP phase can be determined via subsequent X-ray diffrac-
tion (XRD) analysis of the scaffold regions [ 40 , 41 ]. In order to qualitatively
describe the distribution of CaP mineral content within the multi-compartment
scaffold, combined SEM imaging and energy dispersive X-ray spectroscopy
(EDX) can be used to show both the local pore microstructure at the interface and
to determine the mineral content and spatial distribution of mineral within the
scaffold (Fig. 16.3 )[ 47 ].