Solvent casting/particle leaching

Solvent casting/particle leaching [41, 45] Controlled porosity Controlled interconnectivity (if particles are sintered) Structures generally isotropic Use of organic solvents... 

The authors described several other fabrication techniques, but their conclusions are the important parts of their report Conventional scaffold fabrication techniques are incapable of precisely controlling pore size, pore geometry, spatial distribution of pores and construction of internal channels within the scaffold. They also state that scaffolds produced by the solvent casting-particulate leaching technique cannot guarantee interconnection of pores because interconnection is dependent on whether the adjacent salt particles are in contact. Moreover, only thin scaffold cross sections can be produced due to difficulty in removing salt particles deep in the matrix. 

Fig. 4a, b. Scanning electron photomicrographs of amorphous poly(L-lactic acid) foams a 92% porosity and 30 pm median pore diameter b and 91% porosity and 94 pm median pore diameter. Prepared by a solvent-casting and particulate-leaching method [32] using 90 wt% sieved sodium chloride particles of size range between 0-53 pm and 106-150 pm, respectively... 

Various fabrication methods have been developed in order to attain the 3D scaffold characteristics. In the case of synthetic polymer or polymer-matrix composite scaffolds, the methods include [47] solvent casting and particle leaching, phase separation, extrusion, gas foaming, and free form fabrication. Each method presents certain advantages with respect to others, ranging from ease of manufacture to control of the microstructure/nanostructure. Solvent casting and phase separation methods have been studied at our laboratory. 

Fig. 7 SEM image of a composite scaffold produced by solvent casting and particle leaching. The black arrows indicate glass particles. The magnification bar corresponds to...

The development of foams for medical purposes was described by Radusch [193], To eliminate thermal degradation, as well as to avoid the problems associated with the low melt viscosity, a process was developed based on solvent casting and subsequent particle leaching. Well-defined porous structures can be formed in such a way [197-200], for example, PHB was dissolved in chloroform, the ensuing solution was mixed with water-soluble particles like NaCl, films were then prepared by solvent casting and evaporation and, subsequently, the salt particles were washed out with water. Various foamed structures were thus prepared, depending on the particle size and amount, as well as other parameters, such as the PHB type and its concentration in the chloroform solution. 

Figure 20.1 SEM image of polymer scaffolds synthesized via (a) solvent casting (Boateng et al., 2009), (b) gas blowing, (c) emulsion templating (Janik and Marzec, 2015), (d) particle leaching (Janik and Marzec, 2015), and (e) electrospinning (Tseng et al., 2013).

Solvent casting and particulate leaching (SC/PL) is a simple and commonly used method for fabricating scaffolds for tissue engineering. With an appropriate thermal treatment, porous constructs of synthetic biodegradable polymers can be prepared with specific porosity, surfaceivolume ratio, pore size and crystallinity for different applications. This method involves mixing water-soluble salt (e.g. sodium chloride, sodium citrate) particles into a polymer solution. The mixture is then cast into the mould of the desired shape. After the solvent is removed by evaporation or lyophilization, the salt particles are leached out to obtain a porous structure with the pore shape limited to the cubic crystal shape of the salt. Removal of soluble particles from the interior of a polymer matrix is difficult and limits the thickness of the films prepared to ca. 2 mm [293]. 

Solvent casting and particulate leaching PLGA/HAp Gelatine 23-52 im Salt 67-167 im Open-cell Porogens either gelatin microspheres or NaCl salt particles [154]... 

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