The manufacturing of modern scaffolds with customized geometry and personalization has become possible due to the three‐dimensional (3D) printing technique. A novel type of 3D‐printed scaffolds for bone tissue regeneration based on poly(ε‐caprolactone) (PCL) filled with nanocrystalline cellulose modified by poly(glutamic acid) (PGlu‐NCC) has been proposed in this study. The 3D printing set‐ups were optimized in order to obtain homogeneous porous scaffolds. Both polymer composites and manufactured 3D scaffolds have demonstrated mechanical properties suitable for a human trabecular bone. Compression moduli were in the range of 334–396 MPa for non‐porous PCL and PCL‐based composites, and 101–122 MPa for porous scaffolds made of the same materials. In vitro mineralization study with the use of human mesenchymal stem cells (hMSCs) revealed the larger Ca deposits on the surface of PCL/PGlu‐NCC composite scaffolds. Implantation of the developed 3D scaffolds into femur of the rabbits was carried out to observe close and delayed effects. The histological analysis showed the lowest content of immune cells and thin fibrous capsule, revealing low toxicity of the PCL/PGlu‐NCC scaffolds seeded with rabbit MSCs (rMSCs) to the surrounding tissues. The most pronounced result on the generation of new bone tissue after implantation of PCL/PGlu‐NCC + rMSCs scaffolds was detected by both microcomputed tomography and histological analysis. Around 33% and 55% of bone coverage were detected for composite 3D scaffolds with adhered rMSCs after 1 and 3 months of implantation, respectively. This achievement can be a result of synergistic effect of PGlu, which attracts calcium ions, and stem cells with osteogenic potential.
Biodegradable and biocompatible composites are of great interest as biomedical materials for various regeneration processes such as the regeneration of bones, cartilage and soft tissues. Modification of the filler surface can improve its compatibility with the polymer matrix, and, as a result, the characteristics and properties of composite materials. This work is devoted to the synthesis and modification of aminated graphene with oligomers of glutamic acid and their use for the preparation of composite materials based on poly(ε-caprolactone). Ring-opening polymerization of N-carboxyanhydride of glutamic acid γ-benzyl ester was used to graft oligomers of glutamic acid from the surface of aminated graphene. The success of the modification was confirmed by Fourier-transform infrared and X-ray photoelectron spectroscopy as well as thermogravimetric analysis. In addition, the dispersions of neat and modified aminated graphene were analyzed by dynamic and electrophoretic light scattering to monitor changes in the characteristics due to modification. The poly(ε-caprolactone) films filled with neat and modified aminated graphene were manufactured and carefully characterized for their mechanical and biological properties. Grafting of glutamic acid oligomers from the surface of aminated graphene improved the distribution of the filler in the polymer matrix that, in turn, positively affected the mechanical properties of composite materials in comparison to ones containing the unmodified filler. Moreover, the modification improved the biocompatibility of the filler with human MG-63 osteoblast-like cells.
Synthetic catalysts that could compete with enzymes in term of the catalytic efficiency but surpass them in stability have a great potential for the practical application. In this work, we have developed a novel kind of organic catalysts based on flow-through macroporous polymer monoliths containing catalytic centers that mimic the catalytic site of natural enzyme chymotrypsin. It is known that chymotrypsin catalytic center consists of L-serine, L-histidine, and L-aspartic acid and has specificity to C-terminal residues of hydrophobic amino acids (L-phenylalanine, L-tyrosine, and L-tryptophan). In this paper, we have prepared the macroporous polymer monoliths bearing grafted polymer layer on their surface. The last one was synthesized via copolymerization of N-methacryloyl-L-serine, N-methacryloyl-L-histidine, and N-methacryloyl-L-aspartic acid. The spatial orientation of amino acids in the polymer layer, generated on the surface of monolithic framework, was achieved by coordinating amino acid-polymerizable derivatives with cobalt (II) ions without substrate-mimicking template and with its use. The conditions for the preparation of mimic materials were optimized to achieve a mechanically stable system. Catalytic properties of the developed systems were evaluated towards the hydrolysis of ester bond in a low molecular substrate and compared to the results of using chymotrypsin immobilized on the surface of a similar monolithic framework. The effect of flow rate increase and temperature elevation on the hydrolysis efficiency were evaluated for both mimic monolith and column with immobilized enzyme.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.