Bio-Design and Manufacturing最新文献

Three-dimensional (3D) printing and bioprinting have come into view for a plannable and standardizable generation of implantable tissue-engineered constructs that can substitute native tissues and organs. These tissue-engineered structures are intended to integrate with the patient’s body. Vascular tissue engineering (TE) is relevant in TE because it supports the sustained oxygenization and nutrition of all tissue-engineered constructs. Bioinks have a specific role, representing the necessary medium for printability and vascular cell growth. This review aims to understand the requirements for the design of vascular bioinks. First, an in-depth analysis of vascular cell interaction with their native environment must be gained. A physiological bioink suitable for a tissue-engineered vascular graft (TEVG) must not only ensure good printability but also induce cells to behave like in a native vascular vessel, including self-regenerative and growth functions. This review describes the general structure of vascular walls with wall-specific cell and extracellular matrix (ECM) components and biomechanical properties and functions. Furthermore, the physiological role of vascular ECM components for their interaction with vascular cells and the mode of interaction is introduced. Diverse currently available or imaginable bioinks are described from physiological matrix proteins to nonphysiologically occurring but natural chemical compounds useful for vascular bioprinting. The physiological performance of these bioinks is evaluated with regard to biomechanical properties postprinting, with a view to current animal studies of 3D printed vascular structures. Finally, the main challenges for further bioink development, suitable bioink components to create a self-assembly bioink concept, and future bioprinting strategies are outlined. These concepts are discussed in terms of their suitability to be part of a TEVG with a high potential for later clinical use.

Autograft or metal implants are routinely used in skeletal repair. However, they fail to provide long-term clinical resolution, necessitating a functional biomimetic tissue engineering alternative. The use of native human bone tissue for synthesizing a biomimetic material ink for three-dimensional (3D) bioprinting of skeletal tissue is an attractive strategy for tissue regeneration. Thus, human bone extracellular matrix (bone-ECM) offers an exciting potential for the development of an appropriate microenvironment for human bone marrow stromal cells (HBMSCs) to proliferate and differentiate along the osteogenic lineage. In this study, we engineered a novel material ink (LAB) by blending human bone-ECM (B) with nanoclay (L, Laponite^®) and alginate (A) polymers using extrusion-based deposition. The inclusion of the nanofiller and polymeric material increased the rheology, printability, and drug retention properties and, critically, the preservation of HBMSCs viability upon printing. The composite of human bone-ECM-based 3D constructs containing vascular endothelial growth factor (VEGF) enhanced vascularization after implantation in an ex vivo chick chorioallantoic membrane (CAM) model. The inclusion of bone morphogenetic protein-2 (BMP-2) with the HBMSCs further enhanced vascularization and mineralization after only seven days. This study demonstrates the synergistic combination of nanoclay with biomimetic materials (alginate and bone-ECM) to support the formation of osteogenic tissue both in vitro and ex vivo and offers a promising novel 3D bioprinting approach to personalized skeletal tissue repair.

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Bone screws are devices used to fix implants or bones to bones. However, conventional screws are mechanically fixed with thread and often face long-term failure due to poor osseointegration. To improve osseointegration, screws are evolving from solid and smooth to porous and rough. Additive manufacturing (AM) offers a high degree of manufacturing freedom, enabling the preparation of predesigned screws that are porous and rough. This paper provides an overview of the problems currently faced by bone screws: long-term loosening and screw breakage. Next, advances in osseointegrated screws are summarized hierarchically (sub-micro, micro, and macro). At the sub-microscale level, we describe surface-modification techniques for enhancing osseointegration. At the micro level, we summarize the micro-design parameters that affect the mechanical and biological properties of porous osseointegrated screws, including porosity, pore size, and pore shape. In addition, we highlight three promising pore shapes: triply periodic minimal surface, auxetic structure with negative Poisson ratio, and the Voronoi structure. At the macro level, we outline the strategies of graded design, gradient design, and topology optimization design to improve the mechanical strength of porous osseointegrated screws. Simultaneously, this paper outlines advances in AM technology for enhancing the mechanical properties of porous osseointegrated screws. AM osseointegrated screws with hierarchical design are expected to provide excellent long-term fixation and the required mechanical strength.

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Bacterial infection is a major problem following bone implant surgery. Moreover, poly-l-lactic acid/carbon nanotube/hydroxyapatite (PLLA/CNT/HAP) bone scaffolds possess enhanced mechanical properties and show good bioactivity regarding bone defect regeneration. In this study, we synthesized silver (Ag)-doped CNT/HAP (CNT/Ag-HAP) nanohybrids via the partial replacing of calcium ions (Ca²⁺) in the HAP lattice with silver ions (Ag⁺) using an ion doping technique under hydrothermal conditions. Specifically, the doping process was induced using the special lattice structure of HAP and the abundant surface oxygenic functional groups of CNT, and involved the partial replacement of Ca²⁺ in the HAP lattice by doped Ag⁺ as well as the in situ synthesis of Ag-HAP nanoparticles on CNT in a hydrothermal environment. The resulting CNT/Ag-HAP nanohybrids were then introduced into a PLLA matrix via laser-based powder bed fusion (PBF-LB) to fabricate PLLA/CNT/Ag-HAP scaffolds that showed sustained antibacterial activity. We then found that Ag⁺, which possesses broad-spectrum antibacterial activity, endowed PLLA/CNT/Ag-HAP scaffolds with this activity, with an antibacterial effectiveness of 92.65%. This antibacterial effect is due to the powerful effect of Ag⁺ against bacterial structure and genetic material, as well as the physical destruction of bacterial structures due to the sharp edge structure of CNT. In addition, the scaffold possessed enhanced mechanical properties, showing tensile and compressive strengths of 8.49 MPa and 19.72 MPa, respectively. Finally, the scaffold also exhibited good bioactivity and cytocompatibility, including the ability to form apatite layers and to promote the adhesion and proliferation of human osteoblast-like cells (MG63 cells).

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Electrocardiogram (ECG) monitoring is used to diagnose cardiovascular diseases, for which wearable electronics have attracted much attention due to their lightweight, comfort, and long-term use. This study developed a wearable multilead ECG sensing system with on-skin stretchable and conductive silver (Ag)-coated fiber/silicone (AgCF-S) dry adhesives. Tangential and normal adhesion to pigskin (0.43 and 0.20 N/cm², respectively) was optimized by the active control of fiber density and mixing ratio, resulting in close contact in the electrode–skin interface. The breathable AgCF-S dry electrode was nonallergenic after continuous fit for 24 h and can be reused/cleaned (>100 times) without loss of adhesion. The AgCF encapsulated inside silicone elastomers was overlapped to construct a dynamic network under repeated stretching (10% strain) and bending (90°) deformations, enabling small intrinsic impedance (0.3 Ω, 0.1 Hz) and contact impedance variation (0.7 kΩ) in high-frequency vibration (70 Hz). All hard/soft modules of the multilead ECG system were integrated into lightweight clothing and equipped with wireless transmission for signal visualization. By synchronous acquisition of I–III, aVR, aVL, aVF, and V4 lead data, the multilead ECG sensing system was suitable for various scenarios, such as exercise, rest, and sleep, with extremely high signal-to-noise ratios.

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A combination of hydrogels and microfluidics allows the construction of biomimetic three-dimensional (3D) tissue models in vitro, which are also known as organ-on-a-chip models. The hydrogel patterning with a well-controlled spatial distribution is typically achieved by embedding sophisticated microstructures to act as a boundary. However, these physical barriers inevitably expose cells/tissues to a less physiologically relevant microenvironment than in vivo conditions. Herein, we present a novel dissolvable temporary barrier (DTB) strategy that allows robust and flexible hydrogel patterning with great freedom of design and desirable flow stimuli for cellular hydrogels. The key aspect of this approach is the patterning of a water-soluble rigid barrier as a guiding path for the hydrogel using stencil printing technology, followed by a barrier-free medium perfusion after the dissolution of the DTB. Single and multiple tissue compartments with different geometries can be established using either straight or curved DTB structures. The effectiveness of this strategy is further validated by generating a 3D vascular network through vasculogenesis and angiogenesis using a vascularized microtumor model. As a new proof-of-concept in vasculature-on-a-chip, DTB enables seamless contact between the hydrogel and the culture medium in closed microdevices, which is an improved protocol for the fabrication of multiorgan chips. Therefore, we expect it to serve as a promising paradigm for organ-on-a-chip devices for the development of tumor vascularization and drug evaluation in the future preclinical studies.

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The subthalamic nucleus (STN) is considered the best target for deep brain stimulation treatments of Parkinson’s disease (PD). It is difficult to localize the STN due to its small size and deep location. Multichannel microelectrode arrays (MEAs) can rapidly and precisely locate the STN, which is important for precise stimulation. In this paper, 16-channel MEAs modified with multiwalled carbon nanotube/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (MWCNT/PEDOT:PSS) nanocomposites were designed and fabricated, and the accurate and rapid identification of the STN in PD rats was performed using detection sites distributed at different brain depths. These results showed that nuclei in 6-hydroxydopamine hydrobromide (6-OHDA)-lesioned brains discharged more intensely than those in unlesioned brains. In addition, the MEA simultaneously acquired neural signals from both the STN and the upper or lower boundary nuclei of the STN. Moreover, higher values of spike firing rate, spike amplitude, local field potential (LFP) power, and beta oscillations were detected in the STN of the 6-OHDA-lesioned brain, and may therefore be biomarkers of STN localization. Compared with the STNs of unlesioned brains, the power spectral density of spikes and LFPs synchronously decreased in the delta band and increased in the beta band of 6-OHDA-lesioned brains. This may be a cause of sleep and motor disorders associated with PD. Overall, this work describes a new cellular-level localization and detection method and provides a tool for future studies of deep brain nuclei.

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Abstract

Traditional tumor models do not tend to accurately simulate tumor growth in vitro or enable personalized treatment and are particularly unable to discover more beneficial targeted drugs. To address this, this study describes the use of three-dimensional (3D) bioprinting technology to construct a 3D model with human hepatocarcinoma SMMC-7721 cells (3DP-7721) by combining gelatin methacrylate (GelMA) and poly(ethylene oxide) (PEO) as two immiscible aqueous phases to form a bioink and innovatively applying fluorescent carbon quantum dots for long-term tracking of cells. The GelMA (10%, mass fraction) and PEO (1.6%, mass fraction) hydrogel with 3:1 volume ratio offered distinct pore-forming characteristics, satisfactory mechanical properties, and biocompatibility for the creation of the 3DP-7721 model. Immunofluorescence analysis and quantitative real-time fluorescence polymerase chain reaction (PCR) were used to evaluate the biological properties of the model. Compared with the two-dimensional culture cell model (2D-7721) and the 3D mixed culture cell model (3DM-7721), 3DP-7721 significantly improved the proliferation of cells and expression of tumor-related proteins and genes. Moreover, we evaluated the differences between the three culture models and the effectiveness of antitumor drugs in the three models and discovered that the efficacy of antitumor drugs varied because of significant differences in resistance proteins and genes between the three models. In addition, the comparison of tumor formation in the three models found that the cells cultured by the 3DP-7721 model had strong tumorigenicity in nude mice. Immunohistochemical evaluation of the levels of biochemical indicators related to the formation of solid tumors showed that the 3DP-7721 model group exhibited pathological characteristics of malignant tumors, the generated solid tumors were similar to actual tumors, and the deterioration was higher. This research therefore acts as a foundation for the application of 3DP-7721 models in drug development research.

Modern medicine is increasingly interested in advanced sensors to detect and analyze biochemical indicators. Ion sensors based on potentiometric methods are a promising platform for monitoring physiological ions in biological subjects. Current semi-implantable devices are mainly based on single-parameter detection. Miniaturized semi-implantable electrodes for multiparameter sensing have more restrictions on the electrode size due to biocompatibility considerations, but reducing the electrode surface area could potentially limit electrode sensitivity. This study developed a semi-implantable device system comprising a multiplexed microfilament electrode cluster (MMEC) and a printed circuit board for real-time monitoring of intra-tissue K⁺, Ca²⁺, and Na⁺ concentrations. The electrode surface area was less important for the potentiometric sensing mechanism, suggesting the feasibility of using a tiny fiber-like electrode for potentiometric sensing. The MMEC device exhibited a broad linear response (K⁺: 2–32 mmol/L; Ca²⁺: 0.5–4 mmol/L; Na⁺: 10–160 mmol/L), high sensitivity (about 20–45 mV/decade), temporal stability (>2 weeks), and good selectivity (>80%) for the above ions. In vitro detection and in vivo subcutaneous and brain experiment results showed that the MMEC system exhibits good multi-ion monitoring performance in several complex environments. This work provides a platform for the continuous real-time monitoring of ion fluctuations in different situations and has implications for developing smart sensors to monitor human health.

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Additive manufacturing (AM) has revolutionized the design and manufacturing of patient-specific, three-dimensional (3D), complex porous structures known as scaffolds for tissue engineering applications. The use of advanced image acquisition techniques, image processing, and computer-aided design methods has enabled the precise design and additive manufacturing of anatomically correct and patient-specific implants and scaffolds. However, these sophisticated techniques can be time-consuming, labor-intensive, and expensive. Moreover, the necessary imaging and manufacturing equipment may not be readily available when urgent treatment is needed for trauma patients. In this study, a novel design and AM methods are proposed for the development of modular and customizable scaffold blocks that can be adapted to fit the bone defect area of a patient. These modular scaffold blocks can be combined to quickly form any patient-specific scaffold directly from two-dimensional (2D) medical images when the surgeon lacks access to a 3D printer or cannot wait for lengthy 3D imaging, modeling, and 3D printing during surgery. The proposed method begins with developing a bone surface-modeling algorithm that reconstructs a model of the patient’s bone from 2D medical image measurements without the need for expensive 3D medical imaging or segmentation. This algorithm can generate both patient-specific and average bone models. Additionally, a biomimetic continuous path planning method is developed for the additive manufacturing of scaffolds, allowing porous scaffold blocks with the desired biomechanical properties to be manufactured directly from 2D data or images. The algorithms are implemented, and the designed scaffold blocks are 3D printed using an extrusion-based AM process. Guidelines and instructions are also provided to assist surgeons in assembling scaffold blocks for the self-repair of patient-specific large bone defects.

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