Strontium-Substituted Nanohydroxyapatite Containing Biodegradable 3D Printed Composite Scaffolds for Bone Regeneration.

Treatment of large-size bone defects is difficult, and acquiring autografts may be challenging due to limited availability. A synthetic patient-specific bone substitute can be developed by using 3D printing technologies in such cases. In the present study, we have developed photocurable composite resins with poly(trimethylene carbonate) (PTMC) containing a high percentage of biodegradable bioactive strontium-substituted nanohydroxyapatite (SrHA, size 30-70 nm).

Porous photo-crosslinked hybrid networks based on poly(trimethylene carbonate-co-ε-caprolactone) and recombinant human-like collagen.

Hybrid hydrogel networks were prepared from recombinant human-like collagen (rh-collagen) and poly(trimethylene carbonate-co-ε-caprolactone) (P (TMC-co-ε-CL)) to overcome the mechanical and bioactivity limitations associated with the respective individual networks. Both polymers were functionalised with methacrylic anhydride to yield photo-crosslinkable materials. Porous hybrid networks of different compositions were prepared by photo-crosslinking frozen mixtures of solutions of the functionalized polymers in acidified DMSO.

In Vitro and In Vivo Degradation of Photo-Crosslinked Poly(Trimethylene Carbonate-co-ε-Caprolactone) Networks.

Three-armed poly(trimethylene carbonate) (PTMC) and poly(trimethylene carbonate-co-Ɛ-caprolactone) (P(TMC-co-ε-CL)) macromers with molecular weights of approximately 30 kg mol are synthesized by ring-opening polymerization and subsequent functionalization with methacrylic anhydride. Networks are then prepared by photo-crosslinking. To investigate the in vitro and in vivo degradation properties of these photo-crosslinked networks and assess the effect of ε-caprolactone content on the degradation properties, PTMC networks, and copolymer networks with two different TMC:ε-CL ratios are prepared.

Patient-Specific Bioimplants and Reconstruction Plates for Mandibular Defects: Production Workflow and In Vivo Large Animal Model Study.

A major challenge with extensive craniomaxillofacial bone reconstruction is the limited donor-site availability to reconstruct defects predictably and accurately according to the anatomical shape of the patient. Here, patient-specific composite bioimplants, consisting of cross-linked poly(trimethylene carbonate) (PTMC) networks and β-tricalcium phosphate (β-TCP), are tested in vivo in twelve Göttingen minipigs in a large mandibular continuity defect model. The 25 mm defects are supported by patient-specific titanium reconstruction plates and receive either osteoconductive composite bioimplants (PTMC+TCP), neat polymer network bioimplants (PTMC), autologous bone segments (positive control), or are left empty (negative control).

Injectable thiol-ene hydrogel of galactoglucomannan and cellulose nanocrystals in delivery of therapeutic inorganic ions with embedded bioactive glass nanoparticles.

We propose an injectable nanocomposite hydrogel that is photo-curable via light-induced thiol-ene addition between methacrylate modified O-acetyl-galactoglucomannan (GGMMA) and thiolated cellulose nanocrystal (CNC-SH). Compared to free-radical chain polymerization, the orthogonal step-growth of thiol-ene addition allows a less heterogeneous hydrogel network and more rapid crosslinking kinetics. CNC-SH reinforced the GGMMA hydrogel as both a nanofiller and a crosslinker to GGMMA resulting in an interpenetrating network via thiol-ene addition.

Polymeric drug delivery systems by additive manufacturing.

Additive manufacturing (AM) is gaining interests in drug delivery applications, offering innovative opportunities for the design and development of systems with complex geometry and programmed controlled release profile. In addition, polymer-based drug delivery systems can improve drug safety, efficacy, patient compliance, and are the key materials in AM. Therefore, combining AM and polymers can be beneficial to overcome the existing limitations in the development of controlled release drug delivery systems.

Improved Bone Regeneration in Rabbit Bone Defects Using 3D Printed Composite Scaffolds Functionalized with Osteoinductive Factors.

Large critical size bone defects are complicated to treat, and in many cases, autografts become a challenge due to size and availability. In such situations, a synthetic bone implant that can be patient-specifically designed and fabricated with control over parameters such as porosity, rigidity, and osteogenic cues can act as a potential synthetic bone substitute. In this study, we produced photocuring composite resins with poly(trimethylene carbonate) containing high ratios of bioactive ceramics and printed porous 3D composite scaffolds to be used as bone grafts.

Native Structure of the Plant Cell Wall Utilized for Top-Down Assembly of Aligned Cellulose Nanocrystals into Micrometer-Sized Nanoporous Particles.

Despite their sustainable appeal, biomass components are currently undervalued in nanotechnology because means to control the assembly of bio-based nanoparticles are lagging behind the synthetic counterparts. Here, micrometer-sized particles consisting of aligned cellulose nanocrystals (CNCs) are prepared by crosslinking cellulose in cotton linter fibers that are prehydrolyzed with gaseous HCl, resulting in chemical cleavage necessary for CNC formation but retaining the morphology of the native fibers. That way, the intrinsic alignment of cellulose microfibrils within the fiber cell wall can be retained and utilized for top-down CNC alignment.

Additive Manufacturing of Bioactive Poly(trimethylene carbonate)/β-Tricalcium Phosphate Composites for Bone Regeneration.

Implants of bioresorbable materials combined with osteoconductive calcium phosphate ceramics show promising results to replace and repair damaged bone tissue. Here we present additive manufacturing of patient-specific porous scaffolds of poly(trimethylene carbonate) (PTMC) including high amounts of β-tricalcium phosphate (β-TCP). Tensile testing of composite networks showed that addition of β-tricalcium phosphate reinforces the composites significantly.

Photo-crosslinked synthetic biodegradable polymer networks for biomedical applications.

Photo-crosslinked synthetic biodegradable polymer networks are highly interesting materials for utilization in biomedical applications such as drug delivery, cell encapsulation and tissue engineering scaffolds. Varying the architecture, chemistry, degree of functionalization and molecular weight of the macromer precursor molecules results in networks with a wide range of physical- and mechanical properties, crosslinking densities, degradation characteristics and thus in potential applications. Photo-crosslinked networks can easily be prepared and have the possibility to entrap a wide range of (biologically active) substances and cells.

Preparation of Designed Poly(trimethylene carbonate) Meniscus Implants by Stereolithography: Challenges in Stereolithography.

Three-armed poly(trimethylene carbonate) macromers with a relatively high molecular weight of 28.9 kg mol are prepared by ring opening polymerization and subsequent functionalization with methacrylate end groups. A resin suitable for processing by stereolithography is developed using propylene carbonate as a diluent, a photoinitiator, and a dye to control the curing characteristics.

Degradation behavior of, and tissue response to photo-crosslinked poly(trimethylene carbonate) networks.

Photo-crosslinked networks prepared from three-armed methacrylate functionalized PTMC oligomers (PTMC-tMA macromers) are attractive materials for developing an anatomically correct meniscus scaffold. In this study, we evaluated cell specific biocompatibility, in vitro and in vivo degradation behavior of, and tissue response to, such PTMC networks. By evaluating PTMC networks prepared from PTMC-tMA macromers of different molecular weights, we were able to assess the effect of macromer molecular weight on the degradation rate of the PTMC network obtained after photo-crosslinking.

Mold-Based Application of Laser-Induced Periodic Surface Structures (LIPSS) on Biomaterials for Nanoscale Patterning.

Laser-induced periodic surface structures (LIPSS) are highly regular, but at the same time contain a certain level of disorder. The application of LIPSS is a promising method to functionalize biomaterials. However, the absorption of laser energy of most polymer biomaterials is insufficient for the direct application of LIPSS.

Biomaterials in search of a meniscus substitute.

The menisci fulfill key biomechanical functions in the tibiofemoral (knee) joint. Unfortunately meniscal injuries are quite common and most often treated by (partial) meniscectomy. However, some patients experience enduring symptoms, and, more importantly, it leads to an increased risk for symptomatic osteoarthritis.