Bionic structure and biocompatibilities of long chain branched poly(L-lactic acid) oriented microcellular foaming material.

In order to solve the problem of uneven microporous structure of Poly(L-lactic acid) (PLLA) bulk orientation by using biological safety multi-functional plant oil as chain extenders (CE), multi-armed flexible chains were introduced into PLLA through reactive processing to prepare long chain branched PLLA (LCB-PLLA). When the total content of the CE was 6.15 wt%, PLLA and the CE reacted most fully, while maintaining the tensile strength of PLLA and improving toughness. After introducing the LCB structure, the presence of multi-armed flexible chains increased the mobility of the molecular chains, resulting in a significantly lower degree of crystallinity. When the draw ratio up to 900 %, the crystallinity of LCB-PLLA-F-900 % was only 45.15 %, lower than that of PLLA-F-900 %. Thanks to the mobility of polymer chains can be enhanced, which reduces the degree of crystallinity while promoting the uniform growth of oriented microporous structures. Finally, an oriented micro-porous biomimetic LCB-PLLA material with an average cell diameter of 540 nm was prepared, and the results of in vitro cell culture showed that the oriented micro-porous LCB-PLLA biomimetic material was more conducive to cell proliferation.

Bionic structure and blood compatibility of highly oriented homo-epitaxially crystallized poly(l-lactic acid).

A highly oriented poly(l-lactic acid) (PLLA), with a blood vessel-like biomimetic structure, was fabricated using solid-phase hot drawing technology and homo-epitaxial crystallization to improve the mechanical properties and biocompatibility of PLLA. Long chain branched PLLA (LCB-PLLA) was prepared through a two-step ring-opening reaction, and a consequent draw as high as 1000 % was achieved during the hot drawing. The modulus and tensile strength were found to have increased through the formation of oriented shish-kebab like crystals along the drawing direction during processing. Furthermore, PLLA nano-lamellae were formed on the surface of the oriented plates via the introduction of homo-epitaxial crystallization. The high degree of orientation and epitaxial crystallization substantially enhanced the biocompatibility of the PLLA by prolonging clotting time, decreasing the rate of hemolysis, and increasing the cell growth and reproduction of the osteoblasts.

[Construction and application of virtual simulation teaching platform for in-hospital emergency nursing of craniofacial injury patients].

PURPOSE: To construct a virtual simulation teaching platform for in-hospital emergency nursing of craniofacial injury patients by virtual simulation technology, and to evaluate its application effect. METHODS: Through virtual reality, animation, human-computer interaction and other technologies, a 3D experiment scene based on high simulation virtual human was constructed to reproduce the virtual rescue scenes of craniofacial injury patients, such as emergency reception, first-aid cooperation, massive hemorrhage rescue cooperation, and tracheotomy cooperation in emergency rescue of sudden airway obstruction, and exercise modules and assessment modules were set. In the virtual simulation platform, the students used the holistic nursing theory and the PDCA cycle method to observe, evaluate and care for craniofacial injury patients. Preliminary evaluation of the platform was carried out in the training of 62 dental nurses. RESULTS: The virtual simulation platform could improve students' comprehensive first-aid ability for craniofacial injury patients. The item with the highest satisfaction rate for the virtual simulation platform was the consistency between the content of the virtual simulation platform and the theoretical course (the satisfaction rate was 91.9%), and the lowest satisfaction rate was the convenience of the virtual simulation platform operation and the page setting (the satisfaction rate was 80.6%). The evaluation module of the virtual simulation platform showed that the highest score of the comprehensive evaluation was 97, the lowest score was 56, and the average score was 80.2. CONCLUSIONS: The virtual simulation teaching platform for in-hospital first aid of craniofacial injury patients can create an immersive learning mode, provide an intuitive rescue experience to the students, and improve their comprehensive first-aid ability.

Preparation and properties of oriented microcellular Poly(l-lactic acid) foaming material.

Poly(l-lactic acid) (PLLA) displays simultaneous repair and regeneration properties. Therefore, it is vital for developing bone repair materials while improving their mechanical strength, and biocompatibility is essential for guaranteeing its application. In this manuscript, using solid hot drawing (SHD) technology to fabricate an oriented shish-kebab like structure, furthermore, the interface-oriented grain boundary controlled the nucleation site and cell morphology during low temperature supercritical carbon dioxide (SC-CO2) foaming process, resulted in an oriented microcellular structure which was similar to load-bearing bone. The tensile strength, elastic modulus, and elongation at break of the oriented microcellular PLLA were 98.4 MPa, 3.3 GPa, and 16.4%, respectively. Furthermore, the biomimetic structure improved osteoblast cells (MC3T3) attachment, proliferation, and propagation. These findings may pave the way for designing novel biomaterials for bone fixation or tissue engineering devices.

Oriented homo-epitaxial crystallization of polylactic acid displaying a biomimetic structure and improved blood compatibility.

Epitaxial crystallization and solid hot-drawing technology were employed to fabricate oriented homo-epitaxial crystallization of polylactic acid (PLA) with nano-topography to enhance its blood compatibility and mechanical characteristics as blood-contacting medical devices. The process involved solid hot stretching the PLA plates. A PLA nutrient solution was then used to immerse the oriented plates to dissolve some of the PLA solutes, ensuring plate integrity. Consequently, the drawing process exponentially enhanced the modulus and tensile strength of the PLA. Orientation and epitaxial crystallization could substantially enhance blood compatibility of PLA by prolonging clotting time and decreasing hemolysis rate, protein adsorption, and platelet activation. The oriented homo-epitaxial crystallization of PLA exhibited a nano-topography and fibrous structure similar to the intimal layer of a blood vessel, and this biomimetic structure was advantageous in decreasing the activation and/or adhesion of platelets.

Electrospun nanofibers for bone regeneration: from biomimetic composition, structure to function.

In recent years, a variety of novel materials and processing technologies have been developed to prepare tissue engineering scaffolds for bone defect repair. Among them, nanofibers fabricated via electrospinning technology have attracted much interest owing to the unique feature of highly mimicking the natural bone extracellular matrix. In particular, many achievements have been made in this field over the past several years. Therefore, this review aims to summarize the most recent advances and highlights of electrospun nanofibers in bone regeneration applications, by focusing on their material compositions (synthetic polymers, natural polymers, composite nanofibers, and hybrid nanofibers), structural regulation strategies (aligned structures, core-shell structures, gradient structures, and three-dimensional structures), function regulation achievements (biomineralization, osteogenesis, vascularization, immunomodulatory, and anti-infection), and combination with other emerging scaffold fabrication technologies (3D printing, electrospraying, and microfluidics). Finally, the future challenges of nanofibrous scaffolds in this field are also discussed briefly. It is anticipated that this review will provide useful insights into the future development of nanofibrous scaffolds in tissue engineering and bone regeneration applications.