Serdiuk, Vitalii

AbstractDegenerative spinal pathology is a widespread medical issue, and spine fusion surgeries are frequently performed. In this study, we fabricated an injectable bioactive click chemistry polymer cement for use in spinal fusion and bone regrowth. Taking advantages of the bioorthogonal click reaction, this cement can be crosslinked by itself eliminating the addition of a toxic initiator or catalyst, nor any external energy sources like UV light or heat. Furthermore, nano‐hydroxyapatite (nHA) and microspheres carrying recombinant human bone morphogenetic protein‐2 (rhBMP‐2) and recombinant human vascular endothelial growth factor (rhVEGF) were used to make the cement bioactive for vascular induction and osteointegration. After implantation into a rabbit posterolateral spinal fusion (PLF) model, the cement showed excellent induction of new bone formation and bridging bone, achieving results comparable to autograft control. This is largely due to the osteogenic properties of nano‐hydroxyapatite (nHA) and the released rhBMP‐2 and rhVEGF growth factors. Since the availability of autograft sources is limited in clinical settings, this injectable bioactive click chemistry cement may be a promising alternative for spine fusion applications in addressing various spinal conditions.

Abstract Polycaprolactone fumarate (PCLF) is a cross‐linkable PCL derivative extensively considered for tissue engineering applications. Although injection molding has been widely used to develop PCLF scaffolds, platforms developed using such technique lack precise control on architecture, design, and porosity required to ensure adequate cellular and tissue responses. In particular, the scaffolds should provide a suitable surface for cell attachment and proliferation, and facilitate cell–cell communication and nutrient flow. 3D printing technologies have led to new architype for biomaterial development with micro‐architecture mimicking native tissue. Here, we developed a method for 3D printing of PCLF structures using the extrusion printing technique. The crosslinking property of PCLF enabled the unique post‐processing of 3D printed scaffolds resulting in highly porous and flexible PCLF scaffolds with compressive properties imitating natural features of cancellous bone. Generated scaffolds supported excellent attachment and proliferation of mesenchymal stem cells (MSC). The high porosity of PCLF scaffolds facilitated vascularized membrane formation demonstrable with the stringency of the ex ovo chicken chorioallantoic membrane (CAM) implantation. Furthermore, upon implantation to rat calvarium defects, PCLF scaffolds enabled an exceptional new bone formation with a bone mineral density of newly formed bone mirroring native bone tissue. These studies suggest that the 3D‐printed highly porous PCLF scaffolds may serve as a suitable biomaterial platform to significantly expand the utility of the PCLF biomaterial for bone tissue engineering applications.

AbstractA series of reactive copolymers with peroxide functionality (RCPFs) were synthesized via radical copolymerization of monomer mixtures in an organic solvent comprised of a peroxide monomer 5‐(tert‐butyl peroxy)‐5‐methylhex‐1‐en‐3‐yne, acrylamide, maleic anhydride, and butyl methacrylate. Peroxide functionality allows the RCPFs to initiate a variety of radical processes, including cross‐linking of organic polymers. Hydrophilic monomer subunits (acrylamide and maleic anhydride) within the RCPF macromolecules promote cross‐linking of water‐soluble polymers. We aimed to investigate RCPF comonomer ratio and its effects on copolymerization kinetics and composition, as well as physico‐chemical and colloidal properties. We also evaluated and characterized the kinetic parameters of the thermal decomposition of peroxide moieties in the synthesized RCPF. Findings revealed that RCPF possessed surface‐active properties and reduced surface tension at its aqueous solution–air interface. The data indicated that the decomposition process complied with the first‐order kinetics, and complex thermal analysis confirmed the presence of peroxide moieties. RCPFs' ability to cross‐link water‐soluble polymers was demonstrated on poly(acrylamide) and poly(vinyl alcohol).

AbstractMagnetite nanoparticles (Fe3O4 NPs) with peroxide‐containing polymer shell have been synthesized using the method of coprecipitation from the mixture solutions of Fe (II) and Fe (III) salts in the presence of peroxide‐containing copolymer (PCC). Polymer shell presence has been proved by elemental and complex thermal analysis. Synthesized Fe3O4 NPs possess superparamagnetic properties. Their specific saturation magnetization decreases gradually from 65 to 54 A·m2·kg−1 with increasing PCC concentration owing to the surface spin pinning effect caused by a polymer shell. The average sizes of Fe3O4 NPs estimated from the data of XRD analysis and magnetic measurements are in the range of 9–12 nm. The NP sizes determined by the DLS method lie in the range of 150–270 nm; this result is significantly larger than the sizes estimated by the two aforementioned methods evidencing a tendency for Fe3O4 NPs toward self‐association. Cross‐linked composite films based on polyvinyl alcohol have been obtained via radical curing initiated by the PCC shell of nanoparticles. The resulting composite films are magnetically sensitive films with rather high physico‐mechanical properties (tensile strength reaches 48–67 MPa and relative elongation – 4%–21% depending on cross‐linking degree), a priori non‐toxic and biocompatible, which makes them promising materials for various applications.