Abstract:The field of bioprinting has made significant advancements in recent years and allowed for the precise deposition of biomaterials and cells. However, within this field lies a major challenge, which is developing high resolution constructs, with complex architectures. In an effort to overcome these challenges a biofabrication technique known as vat polymerization is being increasingly investigated due to its high fabrication accuracy and control of resolution (µm scale). Despite the progress made in developing … Show more
“…In comparison to the previous studies, where a CNF hydrogel and auxiliary methacrylate components such as gelatine and biopolymer methacrylate were formulated, the current CNF-MA ink showed more suitability in manufacturing relatively soft hydrogel matrix applications. , Thus, further development should be explored to extend the stiffness range of the hydrogel by altering the cross-linker and increasing the DS of MA, which is shown to be a challenge while aiming at relatively higher content of biopolymers in the formulation. Moreover, it is worth pointing out that in response to the strong need for precise deposition of biomaterials and cells, a high-resolution construct with a complex structure can be fabricated by vat polymerization that faces a major challenge in developing soft bioresins for cell encapsulation, , where the CNF-MA inks likely to have potential and will be investigated.…”
In the context of three-dimensional (3D) cell culture and tissue engineering, 3D printing is a powerful tool for customizing in vitro 3D cell culture models that are critical for understanding the cell−matrix and cell−cell interactions. Cellulose nanofibril (CNF) hydrogels are emerging in constructing scaffolds able to imitate tissue in a microenvironment. A direct modification of the methacryloyl (MA) group onto CNF is an appealing approach to synthesize photocross-linkable building blocks in formulating CNF-based bioinks for light-assisted 3D printing; however, it faces the challenge of the low efficiency of heterogenous surface modification. Here, a multistep approach yields CNF methacrylate (CNF-MA) with a decent degree of substitution while maintaining a highly dispersible CNF hydrogel, and CNF-MA is further formulated and copolymerized with monomeric acrylamide (AA) to form a super transparent hydrogel with tuneable mechanical strength (compression modulus, approximately 5−15 kPa). The resulting photocurable hydrogel shows good printability in direct ink writing and good cytocompatibility with HeLa and human dermal fibroblast cell lines. Moreover, the hydrogel reswells in water and expands to all directions to restore its original dimension after being air-dried, with further enhanced mechanical properties, for example, Young's modulus of a 1.1% CNF-MA/1% PAA hydrogel after reswelling in water increases to 10.3 kPa from 5.5 kPa.
“…In comparison to the previous studies, where a CNF hydrogel and auxiliary methacrylate components such as gelatine and biopolymer methacrylate were formulated, the current CNF-MA ink showed more suitability in manufacturing relatively soft hydrogel matrix applications. , Thus, further development should be explored to extend the stiffness range of the hydrogel by altering the cross-linker and increasing the DS of MA, which is shown to be a challenge while aiming at relatively higher content of biopolymers in the formulation. Moreover, it is worth pointing out that in response to the strong need for precise deposition of biomaterials and cells, a high-resolution construct with a complex structure can be fabricated by vat polymerization that faces a major challenge in developing soft bioresins for cell encapsulation, , where the CNF-MA inks likely to have potential and will be investigated.…”
In the context of three-dimensional (3D) cell culture and tissue engineering, 3D printing is a powerful tool for customizing in vitro 3D cell culture models that are critical for understanding the cell−matrix and cell−cell interactions. Cellulose nanofibril (CNF) hydrogels are emerging in constructing scaffolds able to imitate tissue in a microenvironment. A direct modification of the methacryloyl (MA) group onto CNF is an appealing approach to synthesize photocross-linkable building blocks in formulating CNF-based bioinks for light-assisted 3D printing; however, it faces the challenge of the low efficiency of heterogenous surface modification. Here, a multistep approach yields CNF methacrylate (CNF-MA) with a decent degree of substitution while maintaining a highly dispersible CNF hydrogel, and CNF-MA is further formulated and copolymerized with monomeric acrylamide (AA) to form a super transparent hydrogel with tuneable mechanical strength (compression modulus, approximately 5−15 kPa). The resulting photocurable hydrogel shows good printability in direct ink writing and good cytocompatibility with HeLa and human dermal fibroblast cell lines. Moreover, the hydrogel reswells in water and expands to all directions to restore its original dimension after being air-dried, with further enhanced mechanical properties, for example, Young's modulus of a 1.1% CNF-MA/1% PAA hydrogel after reswelling in water increases to 10.3 kPa from 5.5 kPa.
“…[ 39 , 40 , 41 , 42 , 43 ] Specifically, in the fabrication of medical devices and implants, acylphosphane oxides may play a prominent role. [ 44 , 45 , 46 ] Given the broad range of possible applications of acylphosphane oxides as photoactive components, it is surprising that only few derivatives have been synthesized or commercialized. The phospha‐Michael addition (PMA) between bis(mesitoyl)phosphine, BAPH, and a number of activated olefins can be promoted either by potassium or caesium salts under basic conditions in a biphasic ether/water solvent system.…”
Addition ofthe PÀ H bond in bis(mesitoyl)phosphine, HP(COMes) 2 (BAPH), to a wide variety of activated carbon-carbon double bonds as acceptors was investigated. While this phospha-Michael addition does not proceed in the absence of an additive or catalyst, excellent results were obtained with stoichiometric basic potassium or caesium salts. Simple amine bases can be employed in catalytic amounts, and tetramethylguanidine (TMG) in particular is an outstanding catalyst that allows the preparation of bis(acyl)phosphines, RÀ P(COMes) 2 , under very mild conditions in excellent yields after only a short time. All phosphines RP(COMes) 2 can subsequently be oxidized to the corresponding bis(acyl)phosphane oxides, RPO(COMes) 2 , a substance class belonging to the most potent photoinitiators for radical polymerizations known to date. Thus, a simple and highly atom economic method has been found that allows the preparation of a broad range of photoinitiators adapted to their specific field of application even on a large scale.
“…Besides, for the regeneration of tissues featuring oriented architectures, such as nerve, muscle, tendon, ligament, and teeth, scaffolds with aligned pores are needed to direct cell alignment and migration [ 13 , 33 , 34 , 35 ]. CAD-AM techniques have revolutionized TE fabrication processes as they use medical imaging combined with virtual models and automated layer-by-layer manufacturing to control the composition and structure of porous scaffolds to meet patient-specific requirements [ 25 , 26 ]. Composite scaffolds made of biodegradable polyesters, such as poly-lactide-co-glycolide (PLGA) and poly(e-caprolactone) (PCL), loaded with different types of inorganic osteoinductive fillers were developed to mimic the native bone and osteochondral tissues architecture [ 36 , 37 ].…”
Section: Current Advances Of Synthetic Ecm-mimicking Scaffoldsmentioning
confidence: 99%
“…Several reviews discuss the recent progress of bioprinting in TE scaffold design and fabrication. Most of these works focused their attention on techniques such as extrusion printing and VAT polymerization [ 25 , 26 ]. In contrast, reviews describing current advances of ECM-mimicking scaffolds, and how the CAD-AM of cell-free and cell laden modular tissue units can be used to meet these challenges, are scarce.…”
Tissue engineering needs bioactive drug delivery scaffolds capable of guiding cell biosynthesis and tissue morphogenesis in three dimensions. Several strategies have been developed to design and fabricate ECM-mimicking scaffolds suitable for directing in vitro cell/scaffold interaction, and controlling tissue morphogenesis in vivo. Among these strategies, emerging computer aided design and manufacturing processes, such as modular tissue unit patterning, promise to provide unprecedented control over the generation of biologically and biomechanically competent tissue analogues. This review discusses recent studies and highlights the role of scaffold microstructural properties and their drug release capability in cell fate control and tissue morphogenesis. Furthermore, the work highlights recent advances in the bottom-up fabrication of porous scaffolds and hybrid constructs through the computer-aided assembly of cell-free and/or cell-laden micro-modules. The advantages, current limitations, and future challenges of these strategies are described and discussed.
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