Papers by Author: Yuan Yuan Liu

Abstract: Bio-electrospraying (BES) is becoming an attractive tool for the delivery of cells into scaffolds for tissue engineering applications. In this study, we aimed to electrospray human umbilical vein endothelial cells (HUVECs) and improve the efficiency of BES by designing a new customized multi-hole spinneret. We demonstrated that the multi-hole spinneret could produce continuous and stable jets during BES, and the efficiency was increased by 5–7 times. Morphological observations, trypan blue and sulforhodamine B assays revealed that the HUVECs electrosprayed using the multi-hole spinneret remained viable and proliferated at a rate similar to that of the controls. Thus, the new multi-hole nozzle can considerably improve output for BES without affecting cell morphology, viability, and proliferation.

Abstract: Currently, the developed electrospinning technique is capable of producing sub-micron diameter fibers, has better bionic of the extracellular matrix (ECM) on the size and morphology. Joining the nanofiber network into the porous macro scaffolds by the association of electrospinning with 3D printing technology can effectively support bionic microenvironment and improve the cell compatibility of scaffolds. We prepared the GE/CA-PCL scaffold by the composite approach, and characterized the morphology, cell compatibility and mechanical properties of scaffolds compared to the GE/CA scaffold prepared by single 3D printing technology. The composite molding process of 3D printing and electrospinning is a promising technique used for preparing scaffolds for tissue engineering and clinical medicine.

Abstract: The defective repairing and restructuring of some tissues and organs is becoming a livelihood issue which need settling urgently at present. Using polytechnics to design and prepare regenerated biological scaffolds is now facing a big bottleneck. In this paper, by the study and analyzing of CAD/CAM technology, 3D printing and electro-spinning technology, a new bionic CAD/CAM/3D printing integrated molding platform is expressed to meet the reunification of design and manufacture of regenerated bone scaffolds. Using the integrated molding platform, the Gelatin/chitosan – PVA scaffold were prepared with macro to micro structure. This molding method will help to develop the bio-manufacturing, biological 3D printing and their equipment, and has a realistic significance on pushing human health.

Abstract: The clinical applications of tissue engineering are still limited by the lack of a functional vascular supply in tissue-engineered constructs. In order to improve the pre-vascularization of tissue-engineered scaffold during in vitro culture, in this study, based on three-dimensional (3D) printing technology, using the crosslinking effect of coaxial fluids (sodium alginate and CaCl₂) to prepare vessel-like hollow gel fibers, then layer by layer overlapping into 3D scaffold. The biological 3D printing platform was successfully developed and a coaxial nozzle module was introduced to generate a CaCl₂-in-Alginate coaxial microfluidic. The inner core diameters of the prepared hollow gel fibers were 220~380 micrometers. In addition, the influence of materials concentration and dispensing rates on hollow fiber dimension were investigated, the cell-encapsulated in the printed hollow fibers was realized and the viability of endothelial cells (ECs) was studied with Laser scanning confocal microscopy (LSCM) and Live-Dead cell staining. The 3D scaffold built by hollow fibers could improve the phenomenon of diffusion constrain and enhance the survival rate of those ECs growing at a greater depth in the construct. This study provides a new theoretical basis for the vascularization of bone scaffold.

Abstract: LDM process is used for preparing three-dimensional scaffolds for tissue engineering rapid prototyping technologies. Because of its forming process is complex, which influenced by a variety of factors, so the processing environment is not stable, the forming of scaffold pore size can not be guaranteed, therefore the forming precision is poor. However, the scaffold pore size accuracy is mainly decided by the wire filament width. Neural network theory and development provides a powerful tool for the study of nonlinear systems. This article analyzed the influence factors for forming bone scaffold filament width of LDM process, based on improved BP neural network, using MATLAB software programming, then predicted the filament width. The results show that model prediction error was less than 8%, it has high forecasting precision, and it can be used to guide the LDM process parameter selection and forming precision of prediction.

Abstract: To solve vacuum casting process exist two-component polyurethane difficult to uniform mixing problems. A non-symmetric eccentric large blade agitator was proposed and the speed was period changed to strengthen the mixed effects. A fluid dynamics of variable speed agitator tank was proposed to numerical simulation flow behacior with Euler - Euler two-fluid model and the dynamic mesh (SM) method. Though numerical simulate to study flow field characteristics of variable speed agitator tank.. The experiment results show that the proposed method can not only achieve high viscosity polyurethane resin with uniform mixing, and shorten the processing time. Effectively solve the polyurethane resin materials difficult to uniform mixing problems.

Abstract: The scaffold is a key part of the artificial regeneration osseous tissues. The ideal scaffold will have the ability to mimic the fully functional tissue, which can afford the fibrous form and complex function of the native ECM. Although Low-temperature deposition manufacturing is a promising method for fabricate tissue scaffold because scaffold can maintain a good performance of biomaterials in low temperature, the scaffold pore size can not be controlled according to demands. Therefore, the key factors that affect the pore size of bone scaffolds are firstly analyzed. Then the mechanism for on-line control is given. Finally, an automatic control system is proposed and some experimental results are given, which have demonstrated the effects of processing parameters on the Shaping of scaffold material.

Abstract: From the perspective of forming bone scaffold, the technologic parameters of LDM which have important influence on the shape of the deposition material are studied. Through building experimental platform and using chitosan solution as experimental material, the influence of the temperature and the layer height on the lap of every fiber layer are firstly discussed in detail. Besides, the effects of nozzle diameter, the velocity of receiving device, the pressure of feeding device are also discussed. Then the above mentioned process parameters are all optimized, which make the forming mechanism of LDM to be clear. Finally, based on the optimal parameters, the scaffold with self-designed pore size and a high degree of pore interconnectivity, which meeting the requirements of the structure of tissue engineering are fabricated.

Abstract: Low-temperature deposition manufacturing (LDM) has been proven as an effective bone scaffold preparation process, but its further application has been seriously hindered by the existing material over-accumulation problem. In view of the over-accumulation problem of the traditional pneumatic extrusion material feeding way, designed and developed a feeding system based on pneumatic-extrusion and valve-control, which can achieve rapid pressure/relief, Combined with the inflation / deflation time calculation method of fixed volume container for analysis and calculation. A unified data management method of the material feeding device and a regulation scheme of the controller are given. Experimental results show that, by adjusting parameters, the feeding system based on pneumatic-extrusion and valve-control can achieve rapid gas pressure/relief, the flux has been well controlled, the over-accumulation on deposition path at the end has been eliminated, which lead to effective guarantee of scaffold forming quality.

Abstract: Aiming at the problem that current vacuum casting method lack of the filling ability in filling large & thin-wall castings. Therefore, a regulated pressure vacuum casting method is proposed, which using regulated pressure to improve the filling ability. The process and mechanism for regulated pressure vacuum casting method is presented and proved it through the home-made V450N-VD vacuum casting prototype. The results show that the regulated pressure vacuum casting method has higher filling capacity and can provide higher negative pressure during the whole filling process. So regulated pressure vacuum casting method has profound development potential.