Fabrication and characterization of shape memory polyurethane porous scaffold for bone tissue engineering

Advantages and Prospective Implications of Smart Materials in Tissue Engineering: Piezoelectric, Shape Memory, and Hydrogels

Conventional biomaterial is frequently used in the biomedical sector for various therapies, imaging, treatment, and theranostic functions. However, their properties are fixed to meet certain applications. Smart materials respond in a controllable and reversible way, modifying some of their properties because of external stimuli. However, protein-based smart materials allow modular protein domains with different functionalities and responsive behaviours to be easily combined. Wherein, these "smart" behaviours can be tuned by amino acid identity and sequence. This review aims to give an insight into the design of smart materials, mainly protein-based piezoelectric materials, shape-memory materials, and hydrogels, as well as highlight the current progress and challenges of protein-based smart materials in tissue engineering. These materials have demonstrated outstanding regeneration of neural, skin, cartilage, bone, and cardiac tissues with great stimuli-responsive properties, biocompatibility, biodegradability, and biofunctionality.

Research Progress of Shape Memory Polymer and 4D Printing in Biomedical Application

As a kind of smart material, shape memory polymer (SMP) shows great application potential in the biomedical field. Compared with traditional metal-based medical devices, SMP-based devices have the following characteristics: 1) The adaptive ability allows the biomedical device to better match the surrounding tissue after being implanted into the body by minimally invasive implantation; 2) it has better biocompatibility and adjustable biodegradability; 3) mechanical properties can be regulated in a large range to better match with the surrounding tissue. 4D printing technology is a comprehensive technology based on smart materials and 3D printing, which has great application value in the biomedical field. 4D printing technology breaks through the technical bottleneck of personalized customization and provides a new opportunity for the further development of the biomedical field. This paper summarizes the application of SMP and 4D printing technology in the field of bone tissue scaffolds, tracheal scaffolds, and drug release, etc. Moreover, this paper analyzes the existing problems and prospects, hoping to provide a preliminary discussion and useful reference for the application of SMP in biomedical engineering.

Preparation and Characteristic of Polyurethane Powder Adhesives with Heating Resistance Modified by Nanosilica

Polyurethane powder adhesives (PPAs) have a great application prospect in various areas. However, the weakly adhesion property at high temperature greatly hindered its application. In this study, nanosilica as reinforcing agent and dispersing agent has been introduced during the preparation of PPAs. A series of the polyurethane powder adhesives modified by nanosilica were prepared and the influence of adding order of nanosilica on the heat resistance and adhesive strength properties of PPAs has been investigated. The results showed that the T-peel strength of most samples after second heat (heated at 70°C for 24 hours) decreased about 60-80% comparing with the original T-peel strength. However, PPSY only decreased 17.5%, which indicated the nanosilica added after the chain extension reaction, in the prepolymer synthesis could increase the heat resistance performance of polyurethane powder adhesives. It also means the nanosilica was doped between the PU chains keeping the original form as enhancement reagent adding the nanosilica after the chain extension reaction. The excellent heat resistance performance of PPSY could meet the requirements of the industrial gluing in the fields of footwear.

Development of Polyhydroxyalkanoate-Based Polyurethane with Water-Thermal Response Shape-Memory Behavior as New 3D Elastomers Scaffolds

In this study, we report the synthesis of a novel bio-based material from polyhydroxyalkanoate (PHA) with good shape-memory effect (SME) and rapid recovery. In this PHA-based polyurethane (PHP), telechelic-hydroxylated polyhydroxyalkanoate (PHA-diols) and polyethylene glycol (PEG) were used as soft segments, providing thermo-responsive domains and water-responsive regions, respectively. Thus, PHP possesses good thermal-responsive SME, such as high shape fixing (>99%) and shape recovery ratio (>90%). Upon immersing in water, the storage modulus of PHP decreased considerably owing to disruption of hydrogen bonds in the PHP matrix. Their water-responsive SME is also suitable for rapid shape recovery (less than 10 s). Furthermore, these outstanding properties can trigger shape-morphing, enabling self-folding and self-expansion of shapes into three-dimensional (3D) scaffolds for potential biomedical applications.

Comprehensive Treatment and Rehabilitation of Patients With Osteosarcoma of the Mandible

OBJECTIVE

The article studies state-of-the art physical therapeutic techniques as a high degree of relevance to minimize invalidation and improve quality of life for patients with dental osteosarcoma.

MATERIALS AND METHODS

A randomized controlled clinical trial was conducted in 21 patients with osteogenic sarcoma of mandible (C41.1). There were 10 patients in the experimental group and 11 patients in the control group.

RESULTS

A comprehensive treatment and rehabilitation program for patients with osteosarcoma of mandible was developed. The first part of the program comprised 3 basic phases: preop chemotherapy, surgery, and postop rehabilitation. The surgical treatment further included resection of an affected part of the mandible and primary repair of the defect with jaw fragments and an autoimplant joined together with the help of positioning devices. The postop rehabilitation included postop chemotherapy and mesodiencephalic modulation (MDM). The second part of the program comprised preop examination, modeling, using stereolytic 3-dimensional models of the mandible, corrective surgeries, including implantation into the autoimplant-a fragment of patient's fibula, and building of a removable titanium alloy-based denture. MDM sessions were administered after each invasive intervention.

CONCLUSIONS

Higher psychological and physical well-being was observed in the experimental group as compared with the control group (P < 0.01) in 2 weeks after the first surgery and 2 months after scheduled corrective surgeries, which finished in denture installation.

Biomimetic polyurethane/TiO2 nanocomposite scaffolds capable of promoting biomineralization and mesenchymal stem cell proliferation

Scaffolds with extracellular matrix-like fibrous morphology, suitable mechanical properties, biomineralization capability, and excellent cytocompatibility are desired for bone regeneration. In this work, fibrous and degradable poly(ester urethane)urea (PEUU) scaffolds reinforced with titanium dioxide nanoparticles (nTiO2) were fabricated to possess these properties. To increase the interfacial interaction between PEUU and nTiO2, poly(ester urethane) (PEU) was grafted onto the nTiO2. The scaffolds were fabricated by electrospinning and exhibited fiber diameter of <1μm. SEM and EDX mapping results demonstrated that the PEU modified nTiO2 was homogeneously distributed in the fibers. In contrast, severe agglomeration was found in the scaffolds with unmodified nTiO2. PEU modified nTiO2 significantly increased Young's modulus and tensile stress of the PEUU scaffolds while unmodified nTiO2 significantly decreased Young's modulus and tensile stress. The greatest reinforcement effect was observed for the scaffold with 1:1 ratio of PEUU and PEU modified nTiO2. When incubating in the simulated body fluid over an 8-week period, biomineralization was occurred on the fibers. The scaffolds with PEU modified nTiO2 showed the highest Ca and P deposition than pure PEUU scaffold and PEUU scaffold with unmodified nTiO2. To examine scaffold cytocompatibility, bone marrow-derived mesenchymal stem cells were cultured on the scaffold. The PEUU scaffold with PEU modified nTiO2 demonstrated significantly higher cell proliferation compared to pure PEUU scaffold and PEUU scaffold with unmodified nTiO2. The above results demonstrate that the developed fibrous nanocomposite scaffolds have potential for bone tissue regeneration.