Scaffold Material Research Articles

Considerations of growth factor and material use in bone tissue engineering using biodegradable scaffolds in vitro and in vivo

Bone tissue engineering aims to harness materials to develop functional bone tissue to heal ‘critical-sized’ bone defects. This study examined a robust, coated poly(caprolactone) trimethacrylate (PCL-TMA) 3D-printable scaffold designed to augment bone formation. Following optimisation of the coatings, three bioactive coatings were examined, i) elastin-like polypeptide (ELP), ii) poly(ethyl acrylate) (PEA), fibronectin (FN) and bone morphogenetic protein-2 (BMP-2) applied sequentially (PEA/FN/BMP-2) and iii) both ELP and PEA/FN/BMP-2 coatings applied concurrently. The scaffold material was robust and showed biodegradability. The coatings demonstrated a significant (p < 0.05) osteogenic response in vitro in alkaline phosphatase gene upregulation and alkaline phosphatase production. The PCL-TMA scaffold and coatings supported angiogenesis and displayed excellent biocompatibility following evaluation on the chorioallantoic membrane assay. No significant (p < 0.05) heterotopic bone formed on the scaffolds within a murine subcutaneous implantation model, compared to the positive control of BMP-2 loaded collagen sponge following examination by micro-computed tomography or histology. The current studies demonstrate a range of innovative coated scaffold constructs with in vitro efficacy and clearly illustrate the importance of an appropriate in vivo environment to validate in vitro functionality prior to scale up and preclinical application.

Hydroxyapatite/Silk Fibroin Composite Scaffold with a Porous Structure and Mechanical Strength Similar to Cancellous Bone by Electric Field-Induced Gel Technology.

Repair and regeneration of bone tissue defects is a multidimensional process that has been highly challenging to date. The artificial bone scaffold materials, which play a core role, still face the conflict that a biofriendly porous structure will reduce the mechanical performance and accelerate degradation. Herein, a multistage porous structured hydroxyapatite (HA)/silk fibroin (SF) composite scaffold (e-HA/SF) was successfully constructed by cleverly utilizing electric field-induced gel technology. The results indicated that the prepared e-HA/SF scaffolds possess biomimetic hierarchical porous structures with a suitable porosity similar to that of cancellous bone. The HA nanocrystals were uniformly encapsulated in the three-dimensional space of the composite scaffold, thus endowing the e-HA/SF composite scaffolds with an enhanced mechanical performance. Notably, the maximum compression stress and Young's modulus of e-HA/SF-2 scaffolds can reach 24.66 ± 0.88 and 28.91 ± 3.19 MPa, respectively, which are equivalent to those of cancellous bone. Such mechanical performance enhancement was previously unattainable through conventional freeze-drying strategies. Moreover, the introduction of bioactive nano-HA can trigger the optimal cell response in both static and dynamic cell culture experiments in vitro. The e-HA/SF composite scaffold developed in this study can better balance the conflict between the porous structure and mechanical and degradation properties of porous scaffolds.

On the Complex Flow Dynamics of Shear Thickening Fluids Entry Flows

Due to their nature, using shear thickening fluids (STFs) in engineering applications has sparked an interest in developing energy-dissipating systems, such as damping devices or shock absorbers. The Rheinforce technology allows the design of customized energy dissipative composites by embedding microfluidic channels filled with STFs in a scaffold material. One of the reasons for using microfluidic channels is that their shape can be numerically optimized to control pressure drop (also known as rectifiers); thus, by controlling the pressure drop, it is possible to control the energy dissipated by the viscous effect. Upon impact, the fluid is forced to flow through the microchannel, experiencing the typical entry flow until it reaches the fully developed flow. It is well-known for Newtonian fluid that the entrance flow is responsible for a non-negligible percentage of the total pressure drop in the fluid; therefore, an analysis of the fluid flow at the entry region for STFs is of paramount importance for an accurate design of the Rheinforce composites. This analysis has been numerically performed before for shear-thickening fluids modeled by a power-law model; however, as this constitutive model represents a continuously growing viscosity between end-viscosity plateau values, it is not representative of the characteristic viscosity curve of shear-thickening fluids, which typically exhibit a three-region shape (thinning-thickening-thinning). For the first time, the influence of these three regions on the entry flow on an axisymmetric pipe is analyzed. Two-dimensional numerical simulations have been performed for four STFs consisting of four dispersions of fumed silica nanoparticles in polypropylene glycol varying concentrations (7.5–20 wt%).

ALB–PRF facilitates chondrogenesis by promoting chondrocytes migration, proliferation and differentiation

Cartilage injury is common in orthopedics and cartilage tissue engineering provides a therapeutic direction for cartilage regeneration. Albumin (ALB)–platelet-rich fibrin (PRF) is speculated to be an ideal natural scaffold material for cartilage tissue engineering theoretically as a product derived from human venous blood. Through in vitro and in vivo experiments, it was demonstrated that ALB–PRF displayed porous structure and slowly released growth factors (TGF-β1, PDGF-AA, PDGF-AB, PDGF-BB, EGF, IGF-1 and VEGF), ALB–PRF conditioned media promoted proliferation, migration, adhesion, phenotype maintenance and extracellular matrix secretion of rabbit chondrocytes. Moreover, ALB–PRF facilitated chondrogenesis in vivo, the regenerative cartilage formed by ALB–PRF/chondrocytes was histologically similar to that of natural knee joint cartilage, the regenerative cartilage expressed cartilage differentiation marker (SOX9, ACAN and COL II), and proliferation marker PCNA and secreted abundant glycosaminoglycans (GAGs) in extracellular matrix. In conclusion, ALB–PRF promoted the migration, proliferation and phenotype maintenance of chondrocytes in vitro. Its loose, porous structure and rich growth factors contained enhanced cell adhesion and growing into the materials. ALB–PRF facilitated chondrogenesis of chondrocytes in vivo.

A strategy for introducing biopotency-enhanced chirality coating on bio-magnesium

Biomedical magnesium alloys (Mg) are often considered potential metallic materials for bone repair scaffolds due to their excellent biomechanical properties, biocompatibility, and biodegradability. However, their rapid degradation behavior is insufficient to support the rapid growth and repair of living tissues. The new surface modification methods to slow down the degradation rate of Mg scaffolds and promote the rapid growth of living tissues is urgent. Here, we developed a chiral-enhanced composite functional coating on the surface of biomedical magnesium. Specifically, a chiral supramolecular hydrogel with graphene oxide (GO) was used to simulate the chiral environment of biological systems, enhancing the adsorption of osteogenic growth factors. Additionally, the silane layers cleverly crosslink traditional silane chains with supramolecular chiral fibers through a hydrogen bond network, which allows the bonding strength (critical loads) of the composite coating to be maintained between 245–275 mN and retains structural integrity when soaked in SBF for 7 days. It was found that both MC3T3-E1 cells growth and BMP-2 adhesion were significantly enhanced by GO-added left-handed chiral coatings, which exhibit superior bone growth-promoting effects. In summary, incorporating chiral features into functional coatings represents a transformative approach in the design and application of bone defect repair materials.

Characterization of marine hydroxyapatite and its interest in bone filling in rabbits femoral defect model: In vivo, in vitro, and in silico study

PurposeHydroxyapatite (HA) is a promising scaffold material for bone defect treatment. This study aimed to evaluate the physicochemical and biological properties of a novel marine-derived HA extracted from blue fish scales and assess its potential as a bone substitute for clinical use. Methods80 female New Zealand white rabbits were assigned to 4 groups (n = 20): HA powder (EC group), 3D-printed HA cylinder (I3DFFF group), negative control group (NC group; bone defect without biomaterial), and positive control group (PC group; bone defect treated with commercially synthesized HA). The biomaterials were characterized in vitro using X-ray diffraction, nitrogen adsorption, scanning electron microscopy, emission spectrophotometry, and MTT assays. In vivo evaluation involved the same techniques, supplemented with histological and radiological analyses at 1, 3, 6, and 9 months post-implantation. Molecular docking studies were also performed to investigate HA's effect on RANKL-induced osteoclastogenesis and the NF-κB signaling pathway. ResultsIn vitro characterization showed that marine-derived HA is a mesoporous material with a crystalline structure similar to natural bone. In vivo, the material demonstrated biocompatibility, osteoinductivity, and osteoconductivity, providing a supportive environment for bone regeneration. Molecular docking indicated that HA could inhibit osteoclastogenesis by suppressing the NF-κB signaling pathway. ConclusionOur findings suggest that the two co-products, EC-17 and I3DFFF, possess the necessary physicochemical and biological characteristics to be developed as effective bone substitutes.

Plant-based scaffolds and osteogenesis: a systematic review

Objective: To enhance the understanding and usefulness of decellularised plant tissues as scaffolds for bone tissue engineering, and to review the recent advances in plant-based scaffolds for bone regeneration. Method: The systematic review was conducted from February to June 2022, and comprised literature search on PubMed and Science Direct databases for articles published in the English language between 2013 and June, 2022. The search was conducted using key words ‘plant-based scaffolds and osteogenesis’ and ‘decellularised plant and scaffolds and bone tissue engineering’ and ‘plant root-based scaffold and bone formation’. Full-text articles and short communication covering both in vitro and in vivo studies focussing on plant-based scaffolds for osteogenesis were included. Additional references that satisfied the inclusion criteria were found on Google Scholar and included in the review. Quality evaluation of the studies included was done independently by two researchers, and the risk of bias was calculated and categorised as low, medium and high risk. Results: Of the 564 articles, 10(1.77 %) were included; 6(60%) purely in vitro studies, and 4(40%) studies having both in vitro and in vivo components. Decellularized plant tissue alone was used as three-dimensional scaffold materials in 5(50%) studies, but in 4(40%) studies, plant-based composite scaffolds were used. The risk of bias was medium in 7(70%) studies. Conclusions: Plant-based scaffolds promote osteogenesis, but more in vivo research on plant-based studies is needed to label it as suitable scaffolds for bone tissue engineering. Key Words: Plant-based scaffolds, Osteogenesis, Decellularised Plant, bone tissue engineering, Plant root-based scaffold, Bone formation.

Exploiting the Potential of Decellularized Extracellular Matrix (ECM) in Tissue Engineering: A Review Study.

While significant progress has been made in creating polymeric structures for tissue engineering, the therapeutic application of these scaffolds remains challenging owing to the intricate nature of replicating the conditions of native organs and tissues. The use of human-derived biomaterials for therapeutic purposes closely imitates the properties of natural tissue, thereby assisting in tissue regeneration. Decellularized extracellular matrix (dECM) scaffolds derived from natural tissues have become popular because of their unique biomimetic properties. These dECM scaffolds can enhance the body's ability to heal itself or be used to generate new tissues for restoration, expanding beyond traditional tissue transfers and transplants. Enhanced knowledge of how ECM scaffold materials affect the microenvironment at the injury site is expected to improve clinical outcomes. In this review, recent advancements in dECM scaffolds are explored and relevant perspectives are offered, highlighting the development and application of these scaffolds in tissue engineering for various organs, such as the skin, nerve, bone, heart, liver, lung, and kidney.

Advancements in Polymer Biomaterials as Scaffolds for Corneal Endothelium Tissue Engineering

Corneal endothelial dysfunction is a leading cause of vision loss globally, frequently requiring corneal transplantation. However, the limited availability of donor tissues, particularly in developing countries, has spurred on the exploration of tissue engineering strategies, with a focus on polymer biomaterials as scaffolds for corneal endotlhelium regeneration. This review provides a comprehensive overview of the advancements in polymer biomaterials, focusing on their role in supporting the growth, differentiation, and functional maintenance of human corneal endothelial cells (CECs). Key properties of scaffold materials, including optical clarity, biocompatibility, biodegradability, mechanical stability, permeability, and surface wettability, are discussed in detail. The review also explores the latest innovations in micro- and nano-topological morphologies, fabrication techniques such as electrospinning and 3D/4D bioprinting, and the integration of drug delivery systems into scaffolds. Despite significant progress, challenges remain in translating these technologies to clinical applications. Future directions for research are highlighted, including the need for improved biomaterial combinations, a deeper understanding of CEC biology, and the development of scalable manufacturing processes. This review aims to serve as a resource for researchers and clinician–scientists seeking to advance the field of corneal endothelium tissue engineering.

Sorghum Prolamin Scaffolds-Based Hybrid Cultured Meat with Enriched Sensory Properties.

Cultured meat (CM) has been hailed as a sustainable future meat production technology that requires scaffolds to support cell growth. Plant proteins are the most promising raw materials for edible scaffolds but remain underutilized. In this study, kafirin, an abundant, readily available, and nonallergenic prolamin extracted from red sorghum, was explored to fabricate 3D porous sponge-like scaffolds via a simple template-leaching method. The scaffolds featured fully interconnected pores with a high porosity of approximately 84% and mechanical properties of 1.0-1.9 kPa. Porcine skeletal muscle cells (PSCs) and adipose-derived stem cells (ADSCs) could adhere, proliferate, and differentiate on protein scaffolds. Thereafter, a hybrid CM was produced by culturing porcine ADSCs on kafirin scaffolds for 12 days, integrating plant protein-based and cell-based alternatives. The anthocyanins found in red sorghum contributed to the hybrid CM with meat-like color and antioxidative benefits. Moreover, the hybrid CM prototype demonstrated promising potential in providing higher protein content (22.9%) and unique mouthfeel and appearance characteristics, highlighting the viability of sorghum prolamin in promoting CM production.

Combining human liver ECM with topographically featured electrospun scaffolds for engineering hepatic microenvironment

Liver disease cases are rapidly expanding worldwide, and transplantation remains the only effective cure for end-stage disease. There is an increasing demand for developing potential drug treatments, and regenerative therapies using in-vitro culture platforms. Human decellularized extracellular matrix (dECM) is an appealing alternative to conventional animal tissues as it contains human-specific proteins and can serve as scaffolding materials. Herein we exploit this with human donor tissue from discarded liver which was not suitable for transplant using a synergistic approach to combining biological and topographical cues in electrospun materials as an in-vitro culture platform. To realise this, we developed a methodology for incorporating human liver dECM into electrospun polycaprolactone (PCL) fibres with surface nanotopographies (230–580 nm). The hybrid scaffolds were fabricated using varying concentrations of dECM; their morphology, mechanical properties, hydrophilicity and stability were analysed. The scaffolds were validated using HepG2 and primary mouse hepatocytes, with subsequent results indicating that the modified scaffolds-maintained cell growth and influenced cell attachment, proliferation and hepatic-related gene expression. This work demonstrates a novel approach to harvesting the potential from decellularized human tissues in the form of innovative in-vitro culture platforms for liver.

Photocatalytic scaffolds enhance anticancer performances of bacterial consortium AUN

Microbial metabolism and function are regulated by ambient microenvironment, yet no functional microporous materials are known to regulate anticancer activity of complex bacterial systems. Here we show that a simple scaffold-mediated bacterial culture is useful for enhancing the anticancer therapeutic abilities of a microbial consortium designated as AUN and composed of intratumoural bacteria Proteus mirabilis (A-gyo) and purple photosynthetic bacteria Rhodopseudomonas palustris (UN-gyo). Our discovery of the mechanism by which porous scaffolds influence the bacterial activities of AUN will facilitate further designs of artificial scaffold material for effective treatment against drug-resistant, triple-negative breast cancer models. A polydimethylsiloxane composite artificial scaffold encapsulating light-activatable TiO2 particularly enhanced the therapeutic outcomes of AUN in syngeneic and orthotopic models. These strong anticancer efficacies were synergistically expressed in tumours because of the potent oncolytic ability of AUN with the help of various immune cells. AUN administration to canines showed well tolerability in an exploratory study.

ANALISIS METODE PELAKSANAAN COR BERTAHAP PRECAST PADA PENYELESAIAN PROYEK OVERPASS PT. TALENTA BUMI MARABAHAN STUDI KASUS PADA PROYEK OVERPASS – MARABAHAN

The precast method work is adjusted because the slab elevation is ± 7 meters high, so it takes a lot of scaffolding (material) and time. Determination of precast concrete is done by analyzing preliminary design calculations, precast loading calculations, evaluating the load to be lifted, in the form of precast self-load, for precast concrete lifting time, precast concrete reinforcement, scaffolding calculations against precast self-load. Based on the results of the study for the age of 1 day concrete for the lifting permit of K-35 tons crane more than the precast load, then the load can be carried by the crane. But in the cylinder validation test, the value is obtained on the first day, so the work can be done earlier. As for the top cast with insitu cast method using the coefficient on day 3 with a value of 0.4, the comparative value of Mu = 30.893 tons.m and Mr = 31.877 tons.m according to the cylinder validation test graph with fc' 12 MPa, the work was obtained on day 2 and because the concreting was carried out in the fastest time of 1 day, the casting could be done on day 3 where the quality of concrete compressive strength has met according to PBI'71 regulations.

Tragacanth gum hydrogels with cellulose nanocrystals: A study on optimizing properties and printability

This study investigates a novel all-polysaccharide hydrogel composed of tragacanth gum (TG) and cellulose nanocrystals (CNCs), eliminating the need for toxic crosslinkers. Designed for potential tissue engineering applications, these hydrogels were fabricated using 3D printing and freeze-drying techniques to create scaffolds with interconnected macropores, facilitating nutrient transport. SEM images revealed that the hydrogels contained macropores with a diameter of 100–115 μm. Notably, increasing the CNC content within the TG matrix (30–50 %) resulted in a decrease in porosity from 83 % to 76 %, attributed to enhanced polymer-nanocrystal interactions that produced denser networks. Despite the reduced porosity, the hydrogels demonstrated high swelling ratios (890–1090 %) due to the high water binding capacity of the hydrogel. Mechanical testing showed that higher CNC concentrations significantly improved compressive strength (27.7–49.5 kPa) and toughness (362–707 kJ/m3), highlighting the enhanced mechanical properties of the hydrogels. Thermal analysis confirmed stability up to 400 °C and verified ionic crosslinking with CaCl₂. Additionally, hemolysis tests indicated minimal hemolytic activity, affirming the biocompatibility of the TG/CNC hydrogels. These findings highlight the potential of these hydrogels as advanced materials for 3D-printed scaffolds and injectable hydrogels, offering customizable porosity, superior mechanical strength, thermal stability, and biocompatibility.

Sequential release of vancomycin and BMP-2 from chitosan/nano-hydroxyapatite thermosensitive hydrogel for the treatment of chronic osteomyelitis

In this study, we developed scaffolds materials with microspheres to form a double sustained release system.Chitosan/nano-hydroxyapatite (CS-HA) was used as a drug carrier to construct a sustained-release system for Bone morphogenetic protein-2(BMP-2) and Vancomycin (VAN). Furthermore, VAN and BMP-2 loaded microspheres (Ms) were prepared by the emulsion ultrasonic method.The resultant composites were characterized by Scanning electron microscope (SEM), compressive strength, porosity, and biodegradation. The characterization results showed uniform porous and rough surface, enhanced thermal stability, and highest compressive strength ((1.912 ± 0.012) Kpa, the surface of the two microspheres was slightly folded and showed a regular spherical shape.The loading rate of BMP-2 was (59.611 × 10-4 ± 0.023 × 10-4)% and the encapsulation rate was (6.022 ± 0.005)%. The release rate of vancomycin and BMP-2 was 57.194% and 12.968% respectively. Osteogenic differentiation of Bone marrow mesenchymal stem cells (BMSCs) was confirmed by alkaline phosphatase quantification. The deposition of late osteogenic markers (calcium phosphates) detected by Alizarin red, which indicated extracellular matrix mineralization. The results showed that BMP-2/VAN in CS-HA hydrogel successfully achieved the sequential release of the double drugs, which could benefit bone regeneration.

Zinc and chitosan-enhanced β-tricalcium phosphate from calcined fetal bovine bone for mandible reconstruction.

Mandibular defects pose significant challenges in reconstructive surgery, and scaffold materials are increasingly recognized for their potential to address these challenges. Among various scaffold materials, Beta-tricalcium phosphate (β-TCP) is noted for its exceptional osteogenic properties. However, improvements in its biodegradation rate and mechanical strength are essential for optimal performance. In this study, we developed a novel β-TCP-based scaffold, CFBB, by calcining fetal bovine cancellous bone. To enhance its properties, we modified CFBB with Chitosan (CS) and Zinc (Zn), creating three additional scaffold materials: CFBB/CS, CFBB/Zn2+, and CFBB/Zn2+/CS. We conducted comprehensive assessments of their physicochemical and morphological properties, degradation rates, biocompatibility, osteogenic ability, new bone formation, and neovascularization both in vitro and in vivo. Our findings revealed that all four materials were biocompatible and safe for use. The modifications with CS and Zn2+ significantly improved the mechanical strength, osteogenic, and angiogenic properties of CFBB, while concurrently decelerating its resorption rate. Among the tested materials, CFBB/Zn2+/CS demonstrated superior performance in promoting bone regeneration and vascularization, making it a particularly promising candidate for mandibular reconstruction. The CFBB/Zn2+/CS scaffold material, with its enhanced mechanical, osteogenic, and angiogenic properties, and a controlled resorption rate, emerges as a highly effective alternative for the repair of oral mandible defects. This study underscores the potential of combining multiple bioactive agents in scaffold materials to improve their functionality for specific clinical applications in bone tissue engineering.

Effect of magnesium and calcium ions on the strength and biofunctionality of GelMA/SAMA composite hydrogels.

Natural polymers and synthetic polymers have been extensively studied as scaffold materials, with the former offering advantages such as biocompatibility, biodegradability, and structural similarity to the natural extracellular matrix (ECM). However, the use of natural polymers in extrusion-based 3D printing has been limited by their poor mechanical properties and challenging rheological properties. In this study, gelatin and sodium alginate were utilized as scaffold materials, with the addition of Ca2+ and Mg2+ components to enhance their physical and chemical properties, and influence early cell behavior. Subsequently, these materials were fabricated into scaffolds using 3D printing. Our results demonstrated that the addition of Ca2+ and Mg2+ could improve the compactness of the 3D network structure, mechanical strength, swelling properties and degradation properties of methacrylated gelatin/methacrylated sodium alginate (GelMA/SAMA) composite hydrogel. In vitro cell tests revealed that the GelMA/SAMA composite hydrogel exhibited negligible cytotoxicity and promoted early cell viability, particularly with the higher concentration of Mg2+ in the material. Notably, the extrusion 3D printing process successfully produced GelMA/SAMA scaffolds. These results collectively indicate that GelMA/SAMA composite scaffolds hold promise as potential biomaterials for tissue engineering applications.

Biochemical, toxicological, and microbiological assessment of calcined poultry manure for potential use as bone scaffold material

The biosafety of thermally calcined poultry manure as a hydroxyapatite source for potential use as bone-making material was investigated in this study. In vitro assays were used to determine the sensitivity of the antioxidant properties to the thermal calcination temperature used to process the poultry manure (750, 800, and 850 °C). The effect of the extract of both calcined poultry manure (local) and analytical grade hydroxyapatite (foreign) at various concentrations of 100%–25 % inclusion at (100 mg/kg) body weight intubation for 21 days on kidney, liver, and serum of animal model used was assessed. The results show that the thermally calcined poultry manure-derived hydroxyapatite generally possessed good antioxidant properties with the poultry manure treated at 750 °C having the most promising antioxidant properties compared to those treated at 800 and 850 °C, and hence a more likely improved anti-toxicity potential. The various blends of the analytical high-grade hydroxyapatite and thermally calcined poultry manure hydroxyapatite samples are safe compared to the normal control rats with regards hepatic function and renal function parameters with the equal blend of analytical high grade and thermally calcined poultry manure-derived hydroxyapatite (1:1) possessing the lowest activity concentrations. In addition, the enzymatic (glutathione peroxidase) and non-enzymatic (reduced glutathione) antioxidant concentrations of the experimental animals administered the varied compositions of the analytical high grade and thermally calcined poultry manure-derived hydroxyapatite, were lower when compared to normal control rats. The microbiological evaluation suggests that the calcined poultry manure inclusion at various concentrations could not pose a negative effect on various pathology in the liver, kidney, and blood.

Near-Infrared Carbon Dots With Antibacterial and Osteogenic Activities for Sonodynamic Therapy of Infected Bone Defects.

Repairing infected bone defects is hindered by the presence of stubborn bacterial infections and inadequate osteogenic activity. The incorporation of harmful antibiotics not only fosters the emergence of multidrug-resistant bacteria, but also diminishes the osteogenic properties of scaffold materials. In addition, it is essential to continuously monitor the degradation kinetics of scaffold materials at bone defect sites, yet the majority of bone repair materials lack imaging capability. To address these issues, this study reports for the first time the development of a single nanomaterial with triple functionality: efficient sonodynamic antibacterial activity, accelerated bone defect repair capability, and NIR imaging ability for visualized therapy of infected bone defects. Through rationally regulating the surface functional groups, the obtained multifunctional NIR carbon dots (NIR-CD) exhibit p-n junction-enhanced sonodynamic activity, narrow bandgap-facilitated NIR imaging capability, and negative charge-augmented osteogenic activity. The validation of NIR-CDs antibacterial and osteogenic activities in vivo is conducted by constructing 3D injectable hydrogels encapsulated by NIR-CDs (NIR-CD/GelMA). The implantation of multifunctional NIR-CD/GelMA hydrogel scaffolds in a model of MRSA-infected craniotomy defects results in almost complete restoration of the infected bone defects after 60 days. These findings will provide traceable, renewable, repairable and antibacterial candidate biomaterials for bone tissue engineering.

Three-dimensional breast cancer tumor models based on natural hydrogels: a review.

Breast cancer is the most common cancer in women and one of the deadliest cancers worldwide. According to the distribution of tumor tissue, breast cancer can be divided into invasive and non-invasive forms. The cancer cells in invasive breast cancer pass through the breast and through the immune system or systemic circulation to different parts of the body, forming metastatic breast cancer. Drug resistance and distant metastasis are the main causes of death from breast cancer. Research on breast cancer has attracted extensive attention from researchers. In vitro construction of tumor models by tissue engineering methods is a common tool for studying cancer mechanisms and anticancer drug screening. The tumor microenvironment consists of cancer cells and various types of stromal cells, including fibroblasts, endothelial cells, mesenchymal cells, and immune cells embedded in the extracellular matrix. The extracellular matrix contains fibrin proteins (such as types I, II, III, IV, VI, and X collagen and elastin) and glycoproteins (such as proteoglycan, laminin, and fibronectin), which are involved in cell signaling and binding of growth factors. The current traditional two-dimensional (2D) tumor models are limited by the growth environment and often cannot accurately reproduce the heterogeneity and complexity of tumor tissues in vivo. Therefore, in recent years, research on three-dimensional (3D) tumor models has gradually increased, especially 3D bioprinting models with high precision and repeatability. Compared with a 2D model, the 3D environment can better simulate the complex extracellular matrix components and structures in the tumor microenvironment. Three-dimensional models are often used as a bridge between 2D cellular level experiments and animal experiments. Acellular matrix, gelatin, sodium alginate, and other natural materials are widely used in the construction of tumor models because of their excellent biocompatibility and non-immune rejection. Here, we review various natural scaffold materials and construction methods involved in 3D tissue-engineered tumor models, as a reference for research in the field of breast cancer.