Organic/inorganic composite membranes based on poly(L-lactic-co-glycolic acid) and mesoporous silica for effective bone tissue engineering

Novel shish-kebab structured nanofibrous decorating chitosan unidirectional scaffolds to mimic extracellular matrix for tissue engineering

Electrospun nanofibrous scaffolds are renowned for their ability to mimic the microstructure of the extracellular matrix (ECM). However, they often fail to replicate the geometry of target tissues, and the biocompatibility of these scaffolds those made from synthetic polymers is always limited due to the lack of cell binding sites. To address these issues, we proposed an innovative approach that combined unidirectional freeze-drying and electrospinning. During this process, electrospun polycaprolactone (PCL) nanofibers were chopped into nanofibrils, which range in size up to several hundred micrometers, and were incorporated into the chitosan scaffolds via unidirectional freeze-drying. In these scaffolds, the chitosan phase was responsible for maintaining the structural integrity at the macroscale, while the embedded nanofibers enhanced the surface topography at the microscale. The resulting scaffolds exhibited a high porosity of 90% and an impressive water uptake capacity of 2500%. Furthermore, 3T3 fibroblast cells showed strong interactions with the scaffolds, characterized by high rates of cell proliferation and viability. The cells also displayed significant orientation along the direction of the pores, suggesting that the scaffolds effectively guided cellular growth.

The synergetic effect of hierarchical pores and micro-nano bioactive glass on promoting osteogenesis and angiogenesis in vitro

Hierarchical pores are important structural components of the bone tissue and are closely related to angiogenesis, nutrient transport, and metabolism involved in the repair of a bone defect. Here, we fabricated a composite scaffold having a hierarchical structure, based on micro-nano bioactive glass (MNBG) incorporated into poly (lactic-co-glycolic acid) (PLGA), and with camphene as a pore-forming agent for bone repair. The results showed that camphene formed abundant micropores in the walls of large pores, resulting in hierarchical pore structures ranging from a few microns to a hundred microns. Moreover, there was 2-3 folds increased in compressive modulus and the scaffolds showed a stable degradation rate and a higher degree of apatite crystallization than ordinary porous scaffolds. The results of in vitro studies showed that, when compared to ordinary porous scaffolds, PLGA-MNBG scaffolds with multi-holes could better promote the proliferation of bone marrow mesenchymal stem cells (BMSCs) and the expression of angiogenic marker (CD31) of human umbilical vein endothelial cells (HUVECs).

Membranes for the life sciences and their future roles in medicine

Since the global outbreak of COVID-19, membrane technology for clinical treatments, including extracorporeal membrane oxygenation (ECMO) and protective masks and clothing, has attracted intense research attention for its irreplaceable abilities. Membrane research and applications are now playing an increasingly important role in various fields of life science. In addition to intrinsic properties such as size sieving, dissolution and diffusion, membranes are often endowed with additional functions as cell scaffolds, catalysts or sensors to satisfy the specific requirements of different clinical applications. In this review, we will introduce and discuss state-of-the-art membranes and their respective functions in four typical areas of life science: artificial organs, tissue engineering, in vitro blood diagnosis and medical support. Emphasis will be given to the description of certain specific functions required of membranes in each field to provide guidance for the selection and fabrication of the membrane material. The advantages and disadvantages of these membranes have been compared to indicate further development directions for different clinical applications. Finally, we propose challenges and outlooks for future development.

3D bioprinted poly(lactic acid)/mesoporous bioactive glass based biomimetic scaffold with rapid apatite crystallization and in-vitro Cytocompatability for bone tissue engineering

In the recent years, bone tissue engineering is regarded as the promising solution for treatment of bone defects which arises due to trauma, infection and surgical intervention. In view of this, several polymer or ceramic based constructs are envisaged for bone tissue engineering potential. However, scaffolds based on pure polymeric materials suffer from slow bioactivity characteristics. On the other hand, scaffolds based on ceramic materials do not offer sufficient strength for load bearing applications. In order to overcome these drawbacks, the current work aims to develop mixed matrix scaffolds based on poly (L-lactic acid)/mesoporous bioactive glass composite with the formulation of 30:70 weight ratio, which mimics the natural bone composition. In the current work, PLA/MBG (30:70) composite based bioink suitable for 3D bioprinting is indigenously developed and its rheological characteristics are evaluated. The 3D architecture for PLA/MBG composite scaffold is designed using Solidworks CAD 2015 and the scaffolds are fabricated using pneumatic based 3D bioprinting technology, which has not been documented earlier for this formulation in view of bone tissue engineering to the best of our knowledge. Followed by this, optimization of printing parameters in order to develop 3D PLA/MBG composite constructs with hierarchical pore architecture suitable for bone tissue engineering is performed. The SEM analysis confirmed that the pore size of the 3D printed PLA/MBG composite scaffolds falls in the range of 500-700 μm, which corresponds to the macroporous nature of the scaffolds useful for bone cell growth. The mechanical analysis confirmed the superior compressive modulus and yield strength for PLA/MBG composite scaffold in comparison to neat PLA. The in-vitro bioactivity assessment showed rapid apatite crystallization by attaining Ca/P ratio of 1.66 equivalent to natural bone mineral within 3rd day of SBF treatment for PLA/MBG composite scaffold, thus indicating the excellent bioactivity behaviour. The 3D bioprinted PLA/MBG composite scaffold showed promising response in terms of cell attachment and proliferation, mineralization as well as gene expression characteristics while assessed through of in-vitro biological assessment using MG-63 osteosarcoma cells. In this regard, the 3D bioprinted PLA/MBG scaffold could be applied as potential implant for bone tissue engineering application.

Nanoarchitectured prototypes of mesoporous silica nanoparticles for innovative biomedical applications

Despite exceptional morphological and physicochemical attributes, mesoporous silica nanoparticles (MSNs) are often employed as carriers or vectors. Moreover, these conventional MSNs often suffer from various limitations in biomedicine, such as reduced drug encapsulation efficacy, deprived compatibility, and poor degradability, resulting in poor therapeutic outcomes. To address these limitations, several modifications have been corroborated to fabricating hierarchically-engineered MSNs in terms of tuning the pore sizes, modifying the surfaces, and engineering of siliceous networks. Interestingly, the further advancements of engineered MSNs lead to the generation of highly complex and nature-mimicking structures, such as Janus-type, multi-podal, and flower-like architectures, as well as streamlined tadpole-like nanomotors. In this review, we present explicit discussions relevant to these advanced hierarchical architectures in different fields of biomedicine, including drug delivery, bioimaging, tissue engineering, and miscellaneous applications, such as photoluminescence, artificial enzymes, peptide enrichment, DNA detection, and biosensing, among others. Initially, we give a brief overview of diverse, innovative stimuli-responsive (pH, light, ultrasound, and thermos)- and targeted drug delivery strategies, along with discussions on recent advancements in cancer immune therapy and applicability of advanced MSNs in other ailments related to cardiac, vascular, and nervous systems, as well as diabetes. Then, we provide initiatives taken so far in clinical translation of various silica-based materials and their scope towards clinical translation. Finally, we summarize the review with interesting perspectives on lessons learned in exploring the biomedical applications of advanced MSNs and further requirements to be explored.

Recent advances in PLGA-based biomaterials for bone tissue regeneration

Bone regeneration is an interdisciplinary complex lesson, including but not limited to materials science, biomechanics, immunology, and biology. Having witnessed impressive progress in the past decades in the development of bone substitutes; however, it must be said that the most suitable biomaterial for bone regeneration remains an area of intense debate. Since its discovery, poly (lactic-co-glycolic acid) (PLGA) has been widely used in bone tissue engineering due to its good biocompatibility and adjustable biodegradability. This review systematically covers the past and the most recent advances in developing PLGA-based bone regeneration materials. Taking the different application forms of PLGA-based materials as the starting point, we describe each form's specific application and its corresponding advantages and disadvantages with many examples. We focus on the progress of electrospun nanofibrous scaffolds, three-dimensional (3D) printed scaffolds, microspheres/nanoparticles, hydrogels, multiphasic scaffolds, and stents prepared by other traditional and emerging methods. Finally, we briefly discuss the current limitations and future directions of PLGA-based bone repair materials. STATEMENT OF SIGNIFICANCE: As a key synthetic biopolymer in bone tissue engineering application, the progress of PLGA-based bone substitute is impressive. In this review, we summarized the past and the most recent advances in the development of PLGA-based bone regeneration materials. According to the typical application forms and corresponding crafts of PLGA-based substitutes, we described the development of electrospinning nanofibrous scaffolds, 3D printed scaffolds, microspheres/nanoparticles, hydrogels, multiphasic scaffolds and scaffolds fabricated by other manufacturing process. Finally, we briefly discussed the current limitations and proposed the newly strategy for the design and fabrication of PLGA-based bone materials or devices.

3D-printed gelatin methacrylate (GelMA)/silanated silica scaffold assisted by two-stage cooling system for hard tissue regeneration

Among many biomaterials, gelatin methacrylate (GelMA), a photocurable protein, has been widely used in 3D bioprinting process owing to its excellent cellular responses, biocompatibility and biodegradability. However, GelMA still shows a low processability due to the severe temperature dependence of viscosity. To overcome this obstacle, we propose a two-stage temperature control system to effectively control the viscosity of GelMA. To optimize the process conditions, we evaluated the temperature of the cooling system (jacket and stage). Using the established system, three GelMA scaffolds were fabricated in which different concentrations (0, 3 and 10 wt%) of silanated silica particles were embedded. To evaluate the performances of the prepared scaffolds suitable for hard tissue regeneration, we analyzed the physical (viscoelasticity, surface roughness, compressive modulus and wettability) and biological (human mesenchymal stem cells growth, western blotting and osteogenic differentiation) properties. Consequently, the composite scaffold with greater silica contents (10 wt%) showed enhanced physical and biological performances including mechanical strength, cell initial attachment, cell proliferation and osteogenic differentiation compared with those of the controls. Our results indicate that the GelMA/silanated silica composite scaffold can be potentially used for hard tissue regeneration.

Comprehensive Survey on Nanobiomaterials for Bone Tissue Engineering Applications

One of the most important ideas ever produced by the application of materials science to the medical field is the notion of biomaterials. The nanostructured biomaterials play a crucial role in the development of new treatment strategies including not only the replacement of tissues and organs, but also repair and regeneration. They are designed to interact with damaged or injured tissues to induce regeneration, or as a forest for the production of laboratory tissues, so they must be micro-environmentally sensitive. The existing materials have many limitations, including impaired cell attachment, proliferation, and toxicity. Nanotechnology may open new avenues to bone tissue engineering by forming new assemblies similar in size and shape to the existing hierarchical bone structure. Organic and inorganic nanobiomaterials are increasingly used for bone tissue engineering applications because they may allow to overcome some of the current restrictions entailed by bone regeneration methods. This review covers the applications of different organic and inorganic nanobiomaterials in the field of hard tissue engineering.

Preparation and characterization of a novel polylactic acid/hydroxyapatite composite scaffold with biomimetic micro-nanofibrous porous structure

Combining synthetic polymer scaffolds with inorganic bioactive factors is widely used to promote the bioactivity and bone conductivity of bone tissue. However, except for the chemical composition of scaffold, the biomimetic structure also plays an important role in its application. In this study, we report the fabrication of polylactic acid/hydroxyapatite (PLA/HA) composite nanofibrous scaffolds via phase separation method to mimic the native extracellular matrix (ECM). The SEM analysis showed that the addition of HA dramatically impacted the morphology of the PLA matrix, which changed from 3D nanofibrous network structure to a disorderly micro-nanofibrous porous structure. At the same time, HA particles could be evenly dispersed at the end of the fiber. The FTIR and XRD demonstrated that there was not any chemical interaction between PLA and HA. Thermal analyses showed that HA could decrease the crystallization of PLA, but improve the thermal decomposition temperature of the composite scaffold. Moreover, water contact angle analysis of the PLA/HA composite scaffold demonstrated that the hydrophilicity increased with the addition of HA. Furthermore, apatite-formation ability tests confirmed that HA could not only more and faster induced the deposition of weak hydroxyapatite but also induced specific morphology of HA.

Silver-decorated mesostructured cellular silica foams as excellent antibacterial hemostatic agents for rapid and effective treatment of hemorrhage

Uncontrolled bleeding, such as deep, narrow or irregular wound hemorrhage, has been a major cause of death in peacetime and wartime. Besides, traditional hemostatic agents are lack of antibacterial properties, which could not provide effective protection on open wound. In this paper, a novel antibacterial hemostatic agent composed of mesostructured cellular silica foams (MCF) decorated with silver ions (MCF-Ag) was synthesized by hydrothermal method. Hemorrhage wound infected with Escherichia coli was applied to evaluate its antibacterial and hemostatic performance both in vitro and in vivo. Both MCF and MCF-Ag showed excellent hemostasis in vitro and in vivo. The MCF-Ag demonstrated significant antibacterial effect. By contrast, no obvious antibacterial effect was observed from the MCF. The above results demonstrate that the MCF-Ag is an excellent antibacterial hemostatic agent with splendid water absorption and antibacterial capacity.

Bone Morphogenic Protein 2-Loaded Porous Silicon Carriers for Osteoinductive Implants

Bone morphogenetic proteins (BMPs) are probably the most important growth factors in bone formation and healing. However, the utilization of BMPs in clinical applications is mainly limited due to the protein poor solubility at physiological pH, rapid clearance and relatively short biological half-life. Herein, we develop degradable porous silicon (PSi)-based carriers for sustained delivery of BMP-2. Two different loading approaches are examined, physical adsorption and covalent conjugation, and their effect on the protein loading and release rate is thoroughly studied. The entrapment of the protein within the PSi nanostructures preserved its bioactivity for inducing osteogenic differentiation of rabbit bone marrow mesenchymal stems cells (BM-MSCs). BM-MSCs cultured with the BMP-2 loaded PSi carriers exhibit a relatively high alkaline phosphatase (ALP) activity. We also demonstrate that exposure of MSCs to empty PSi (no protein) carriers generates some extent of differentiation due to the ability of the carrier's degradation products to induce osteoblast differentiation. Finally, we demonstrate the integration of these promising BMP-2 carriers within a 3D-printed patient-specific implant, constructed of poly(caprolactone) (PCL), as a potential bone graft for critical size bone defects.

Cardiac tissue engineering: state-of-the-art methods and outlook

The purpose of this review is to assess the state-of-the-art fabrication methods, advances in genome editing, and the use of machine learning to shape the prospective growth in cardiac tissue engineering. Those interdisciplinary emerging innovations would move forward basic research in this field and their clinical applications. The long-entrenched challenges in this field could be addressed by novel 3-dimensional (3D) scaffold substrates for cardiomyocyte (CM) growth and maturation. Stem cell-based therapy through genome editing techniques can repair gene mutation, control better maturation of CMs or even reveal its molecular clock. Finally, machine learning and precision control for improvements of the construct fabrication process and optimization in tissue-specific clonal selections with an outlook of cardiac tissue engineering are also presented.

Electrospinning and Electrospun Nanofibers: Methods, Materials, and Applications

Electrospinning is a versatile and viable technique for generating ultrathin fibers. Remarkable progress has been made with regard to the development of electrospinning methods and engineering of electrospun nanofibers to suit or enable various applications. We aim to provide a comprehensive overview of electrospinning, including the principle, methods, materials, and applications. We begin with a brief introduction to the early history of electrospinning, followed by discussion of its principle and typical apparatus. We then discuss its renaissance over the past two decades as a powerful technology for the production of nanofibers with diversified compositions, structures, and properties. Afterward, we discuss the applications of electrospun nanofibers, including their use as "smart" mats, filtration membranes, catalytic supports, energy harvesting/conversion/storage components, and photonic and electronic devices, as well as biomedical scaffolds. We highlight the most relevant and recent advances related to the applications of electrospun nanofibers by focusing on the most representative examples. We also offer perspectives on the challenges, opportunities, and new directions for future development. At the end, we discuss approaches to the scale-up production of electrospun nanofibers and briefly discuss various types of commercial products based on electrospun nanofibers that have found widespread use in our everyday life.

Micro-Nano Bioactive Glass Particles Incorporated Porous Scaffold for Promoting Osteogenesis and Angiogenesis in vitro

Constructing the interconnected porous biomaterials scaffolds with osteogenesis and angiogenesis capacity is extremely important for efficient bone tissue engineering. Herein, we fabricated a bioactive micro-nano composite scaffolds with excellent in vitro osteogenesis and angiogenesis capacity, based on poly (lactic-co-glycolic acid) (PLGA) incorporated with micro-nano bioactive glass (MNBG). The results showed that the addition of MNBG enlarged the pore size, increased the compressive modulus (4 times improvement), enhanced the physiological stability and apatite-forming ability of porous PLGA scaffolds. The in vitro studies indicated that the PLGA-MNBG porous scaffold could enhance the mouse bone mesenchymal stem cells (mBMSCs) attachment, proliferation, and promote the expression of osteogenesis marker (ALP). Additionally, PLGA-MNBG could also support the attachment and proliferation of human umbilical vein endothelial cells (HUVECs), and significantly enhanced the expression of angiogenesis marker (CD31) of HUVECs. The as-prepared bioactive PLGA-MNBG nanocomposites scaffolds with good osteogenesis and angiogenesis probably have a promising application for bone tissue regeneration.

Multifunctional Superparamagnetic Stiff Nanoreservoirs for Blood Brain Barrier Applications

Neurological diseases (Alzheimer's disease, Parkinson's disease, and stroke) are becoming a major concern for health systems in developed countries due to the increment of ageing in the population, and many resources are devoted to the development of new therapies and contrast agents for selective imaging. However, the strong isolation of the brain by the brain blood barrier (BBB) prevents not only the crossing of pathogens, but also a large set of beneficial drugs. Therefore, an alternative strategy is arising based on the anchoring to vascular endothelial cells of nanoplatforms working as delivery reservoirs. In this work, novel injectable mesoporous nanorods, wrapped by a fluorescent magnetic nanoparticles envelope, are proposed as biocompatible reservoirs with an extremely high loading capacity, surface versatility, and optimal morphology for enhanced grafting to vessels during their diffusive flow. Wet chemistry techniques allow for the development of mesoporous silica nanostructures with tailored properties, such as a fluorescent response suitable for optical studies, superparamagnetic behavior for magnetic resonance imaging MRI contrast, and large range ordered porosity for controlled delivery. In this work, fluorescent magnetic mesoporous nanorods were physicochemical characterized and tested in preliminary biological in vitro and in vivo experiments, showing a transversal relaxivitiy of 324.68 mM-1 s-1, intense fluorescence, large specific surface area (300 m² g-1), and biocompatibility for endothelial cells' uptake up to 100 µg (in a 80% confluent 1.9 cm² culture well), with no liver and kidney disability. These magnetic fluorescent nanostructures allow for multimodal MRI/optical imaging, the allocation of therapeutic moieties, and targeting of tissues with specific damage.

Bone remodeling-inspired dual delivery electrospun nanofibers for promoting bone regeneration

Developing a highly bioactive bone tissue engineering scaffold that can modulate the bone remodeling process for promoting bone regeneration is a great challenge. In order to tackle this issue, inspired by the balance between bone resorption and formation in the bone remodeling process, here we developed a mesoporous silicate nanoparticle (MSN)-based electrospun polycaprolactone (PCL)/gelatin nanofibrous scaffold to achieve dual delivery of alendronate (ALN) and silicate for a synergetic effect in modulating bone remodeling, where ALN inhibited the bone-resorbing process via preventing guanosine triphosphate-related protein expression, and silicate promoted the bone-forming process via improving vascularization and bone calcification. The scaffold was successfully prepared by encapsulation of ALN into MSNs (ALN@MSNs) and co-electrospinning of an acetic acid-mediated PCL/gelatin homogeneous solution with well-dispersed ALN@MSNs. The results of ALN and Si element release profiles indicated that the ALN@MSN-loaded nanofibers achieved dual release of ALN and silicate (produced due to the hydrolysis of MSNs) simultaneously. The bone repair data from a rat critical-sized cranial defect model revealed that the developed strategy accelerated the healing time from 12 weeks to 4 weeks, almost three times faster, while the other nanofiber groups only had limited bone regeneration at 4 weeks. In addition, we used interactive double-factor analysis of variance for the data of bone volume and maturity to evaluate the synergetic effect of ALN and silicate in promoting bone regeneration, and the result clearly proved our original design and hypothesis. In summary, the presented bone remodeling-inspired electrospun nanofibers with dual delivery of ALN and silicate may be highly promising for bone repair in the clinic.

Loading BMP-2 on nanostructured hydroxyapatite microspheres for rapid bone regeneration

INTRODUCTION

Tissue engineering is a promising strategy for bone regeneration in repairing massive bone defects. The surface morphology of implanted materials plays a key role in bone healing; these materials incorporate osteoinductive factors to improve the efficiency of bone regeneration.

MATERIALS AND METHODS

In the current study, nanostructured hydroxyapatite (nHAp) micro-spheres were prepared via a hydrothermal transformation method using calcium silicate (CS) microspheres as precursors; the CS microspheres were obtained by a spray-drying method. The nHAp microspheres constructed by the nano-whiskers significantly improved the ability of the microspheres to adsorb the bioactive protein (BMP-2) and reduce its initial burst release. To evaluate the in vivo bone regeneration of microspheres, both conventional hydroxyapatite (HAp) and nHAp microspheres were either loaded with recombinant human bone morphogenetic protein-2 (rhBMP-2) or not loaded with the protein; these microspheres were implanted in rat femoral bone defects for 4 and 8 weeks.

RESULTS AND DISCUSSION

The results of our three-dimensional (3D) micro-computed tomography (CT) and histomorphometric observations showed that the combination of the nano-structured surface and rhBMP-2 obviously improved osteogenesis compared to conventional HAp microspheres loaded with rhBMP-2. Our results suggest that the nHAp microspheres with a nanostructured surface adsorb rhBMP-2 for rapid bone formation; they therefore show the potential to act as carriers in bone tissue regeneration.

Incorporation of Calcium Containing Mesoporous (MCM-41-Type) Particles in Electrospun PCL Fibers by Using Benign Solvents

The electrospinning technique is a versatile method for the production of fibrous scaffolds able to resemble the morphology of the native extra cellular matrix. In the present paper, electrospinning is used to fabricate novel SiO₂ particles (type MCM-41) containing poly(epsilon-caprolactone) (PCL) fibers. The main aims of the present work are both the optimization of the particle synthesis and the fabrication of composite fibers, obtained using benign solvents, suitable as drug delivery systems and scaffolds for soft tissue engineering applications. The optimized synthesis and characterization of calcium-containing MCM-41 particles are reported. Homogeneous bead-free composite electrospun mats were obtained by using acetic acid and formic acid as solvents; neat PCL electrospun mats were used as control. Initially, an optimization of the electrospinning environmental parameters, like relative humidity, was performed. The obtained composite nanofibers were characterized from the morphological, chemical and mechanical points of view, the acellular bioactivity of the composite nanofibers was also investigated. Positive results were obtained in terms of mesoporous particle incorporation in the fibers and no significant differences in terms of average fiber diameter were detected between the neat and composite electrospun fibers. Even if the Ca-containing MCM-41 particles are bioactive, this property is not preserved in the composite fibers. In fact, during the bioactivity assessment, the particles were released confirming the potential application of the composite fibers as a drug delivery system. Preliminary in vitro tests with bone marrow stromal cells were performed to investigate cell adhesion on the fabricated composite mats, the positive obtained results confirmed the suitability of the composite fibers as scaffolds for soft tissue engineering.

Polylactic Acid Nanofiber Scaffold Decorated with Chitosan Islandlike Topography for Bone Tissue Engineering

In this work, a bicomponent scaffold with a core-shell and islandlike structure that combines the respective advantages of polylactic acid (PLA) and chitosan (CS) was prepared via electrospinning accompanied by automatic phase separation and crystallization. The objective of this research was to design nanosized topography with highly bioactive CS onto PLA electrospun fiber surface to improve the cell biocompatibility of the PLA fibrous membrane. The morphology, inner structure, surface composition, crystallinity, and thermodynamic analyses of nanofibers with various PLA/CS ratios were carried out, and the turning mechanism of a core-shell or islandlike topography structure was also speculated. The mineralization of hydroxyapatite and culture results of preosteoblast (MC3T3-E1) cells on the modified scaffolds indicate that the outer CS component and rough nanoscale topography on the surface of the nanofibers balanced the hydrophilicity and hydrophobicity of the fibers, enhanced their mineralization ability, and made them more beneficial for the attachment and growth of cells. Moreover, CS and "islandlike" protrusions on the fiber surface increased the alkaline phosphatase activity of the MC3T3-E1 cells seeded on the fibrous membrane and provided a more appropriate interface for cell adhesion and proliferation. These results illustrate that this kind of PLA/CS membrane has the potential in tissue engineering. More importantly, our study provides a new approach to designing PLA scaffolds, with combined topographic and bioactive modification effects at the interface between cells and materials, for biomedicine.

Nanoporosity improved water absorption, in vitro degradability, mineralization, osteoblast responses and drug release of poly(butylene succinate)-based composite scaffolds containing nanoporous magnesium silicate compared with magnesium silicate

Bioactive composite macroporous scaffold containing nanoporosity was prepared by incorporation of nanoporous magnesium silicate (NMS) into poly(butylene succinate) (PBSu) using solvent casting-particulate leaching method. The results showed that the water absorption and in vitro degradability of NMS/PBSu composite (NMPC) scaffold significantly improved compared with magnesium silicate (MS)/PBSu composite (MPC) scaffold. In addition, the NMPC scaffold showed improved apatite mineralization ability, indicating better bioactivity, as the NMPC containing nanoporosity could induce more apatite and homogeneous apatite layer on the surfaces than MPC scaffold. The attachment and proliferation of MC3T3-E1 cells on NMPC scaffold increased significantly compared with MPC scaffold, and the alkaline phosphatase (ALP) activity of the cells on NMPC scaffold was expressed at considerably higher levels compared with MPC scaffold. Moreover, NMPC scaffold with nanoporosity not only had large drug loading (vancomycin) but also exhibited drug sustained release. The results suggested that the incorporation of NMS into PBSu could produce bioactive composite scaffold with nanoporosity, which could enhance water absorption, degradability, apatite mineralization and drug sustained release and promote cell responses.

Enhanced proliferation and osteogenic differentiation of MC3T3-E1 pre-osteoblasts on graphene oxide-impregnated PLGA–gelatin nanocomposite fibrous membranes

Currently, combining biodegradable polymeric scaffolds with living cells for bone repair has received significant attention.

Poly (lactic acid)-based biomaterials for orthopaedic regenerative engineering

Regenerative engineering converges tissue engineering, advanced materials science, stem cell science, and developmental biology to regenerate complex tissues such as whole limbs. Regenerative engineering scaffolds provide mechanical support and nanoscale control over architecture, topography, and biochemical cues to influence cellular outcome. In this regard, poly (lactic acid) (PLA)-based biomaterials may be considered as a gold standard for many orthopaedic regenerative engineering applications because of their versatility in fabrication, biodegradability, and compatibility with biomolecules and cells. Here we discuss recent developments in PLA-based biomaterials with respect to processability and current applications in the clinical and research settings for bone, ligament, meniscus, and cartilage regeneration.

Nano-Bio Engineered Carbon Dot-Peptide Functionalized Water Dispersible Hyperbranched Polyurethane for Bone Tissue Regeneration

The present study delves into a combined bio-nano-macromolecular approach for bone tissue engineering. This approach relies on the properties of an ideal scaffold material imbued with all the chemical premises required for fostering cellular growth and differentiation. A tannic acid based water dispersible hyperbranched polyurethane is fabricated with bio-nanohybrids of carbon dot and four different peptides (viz. SVVYGLR, PRGDSGYRGDS, IPP, and CGGKVGKACCVPTKLSPISVLYK) to impart target specific in vivo bone healing ability. This polymeric bio-nanocomposite is blended with 10 wt% of gelatin and examined as a non-invasive delivery vehicle. In vitro assessment of the developed polymeric system reveals good osteoblast adhesion, proliferation, and differentiation. Aided by this panel of peptides, the polymeric bio-nanocomposite exhibits in vivo ectopic bone formation ability. The study on in vivo mineralization and vascularization reveals the occurrence of calcification and blood vessel formation. Thus, the study demonstrates carbon dot/peptide functionalized hyperbranched polyurethane gel for bone tissue engineering application.

Biodegradable mesoporous bioactive glass nanospheres for drug delivery and bone tissue regeneration

Bioactive inorganic materials are attractive for hard tissue regeneration, and they are used as delivery vehicles for pharmaceutical molecules, scaffolds and components for bio-composites. We demonstrated mesoporous bioactive glass (BG) nanospheres that exhibited the capacity to deliver pharmaceutical molecules. Mesoporous BG nanospheres with variable Ca to Si ratios were synthesized using sol-gel chemistry. By controlling the hydrolysis and condensation conditions, the diameter of the mesoporous BG nanospheres was changed from 300 nm to 1500 nm. The porous structure and surface area of the BG nanospheres were shown to be dependent on their composition. The surface area of the BG nanospheres decreased from 400 ± 2 m(2) g(-1) to 56 ± 0.1 m(2) g(-1) when the Ca/Si ratio increased from 5 to 50 at.%. When the mesoporous BG nanospheres were loaded with ibuprofen (IBU), they exhibited a sustained release profile in simulated body fluid (SBF). In the meantime, the IBU-loaded BG nanospheres degraded in SBF, and induced apatite layer formation on the surface as a result of their good bioactivity. When the BG nanospheres were used as a composite filler to poly (ε-caprolactone) (PCL), they were shown to be effective at improving the in vitro bioactivity of PCL microspheres.

Photo-immobilization of bone morphogenic protein 2 on PLGA/HA nanocomposites to enhance the osteogenesis of adipose-derived stem cells

Poly(lactide-co-glycolide) and nano-hydroxyapatite composites are surface-modified with BMP-2 via photo-reactive gelatin to make the composites exhibit excellent bioactivities for the adhesion, proliferation and osteogenic differentiation of ADSCs.

Degradability, bioactivity, and osteogenesis of biocomposite scaffolds of lithium-containing mesoporous bioglass and mPEG-PLGA-b-PLL copolymer

Biocomposite scaffolds of lithium (Li)-containing mesoporous bioglass and monomethoxy poly(ethylene glycol)-poly(D,L-lactide-co-glycolide)-poly(L-lysine) (mPEG-PLGA-b-PLL) copolymer were fabricated in this study. The results showed that the water absorption and degradability of Li-containing mesoporous bioglass/mPEG-PLGA-b-PLL composite (l-MBPC) scaffolds were obviously higher than Li-containing bioglass/mPEG-PLGA-b-PLL composite (l-BPC) scaffolds. Moreover, the apatite-formation ability of l-MBPC scaffolds was markedly enhanced as compared with l-BPC scaffolds, indicating that l-MBPC scaffolds containing mesoporous bioglass exhibited good bioactivity. The cell experimental results showed that cell attachment, proliferation, and alkaline phosphatase activity of MC3T3-E1 cells on l-MBPC scaffolds were remarkably improved as compared to l-BPC scaffolds. In animal experiments, the histological elevation results revealed that l-MBPC scaffolds significantly promoted new bone formation, indicating good osteogenesis. l-MBPC scaffolds with improved properties would be an excellent candidate for bone tissue repair.

Mesoporous bioactive glass surface modified poly(lactic-co-glycolic acid) electrospun fibrous scaffold for bone regeneration

A mesoporous bioactive glass (MBG) surface modified with poly(lactic-co-glycolic acid) (PLGA) electrospun fibrous scaffold for bone regeneration was prepared by dip-coating a PLGA electrospun fibrous scaffold into MBG precursor solution. Different surface structures and properties were acquired by different coating times. Surface morphology, chemical composition, microstructure, pore size distribution, and hydrophilicity of the PLGA-MBG scaffold were characterized. Results of scanning electron microscopy indicated that MBG surface coating made the scaffold rougher with the increase of MBG content. Scaffolds after MBG modification possessed mesoporous architecture on the surface. The measurements of the water contact angles suggested that the incorporation of MBG into the PLGA scaffold improved the surface hydrophilicity. An energy dispersive spectrometer evidenced that calcium-deficient carbonated hydroxyapatite formed on the PLGA-MBG scaffolds after a 7-day immersion in simulated body fluid. In vitro studies showed that the incorporation of MBG favored cell proliferation and osteogenic differentiation of human mesenchymal stem cells on the PLGA scaffolds. Moreover, the MBG surface-modified PLGA (PLGA-MBG) scaffolds were shown to be capable of providing the improved adsorption/release behaviors of bone morphogenetic protein-2 (BMP-2). It is very significant that PLGA-MBG scaffolds could be effective for BMP-2 delivery and bone regeneration.

Silica-based mesoporous nanobiomaterials as promoter of bone regeneration process

Silica-based mesostructured nanomaterials have emerged as a full family of biomaterials with tremendous potential to address the requirements for the bone regeneration process. This review focuses on more recent advances in bone regeneration process based on silica-based mesoporous biomaterials during 2012 to January 2015. In this review, we describe application of silica-based mesoporous mesostructured nanomaterials (possessing pore sizes in the range 2-50 nm) for the bone regeneration process. We summarize the preparation methods, the effect of mesopore templates and composition on the mesopore-structure characteristics, and different forms of these materials, including particles, fibers, spheres, scaffolds, and composites. The effect of structural and textural properties of mesoporous materials on the development of new biomaterials for treatment of different bone pathologies such as infection, osteoporosis, cancer, and so forth is discussed. In addition, silica-based mesoporous bioactive glass, as a potential drug/growth factor carrier, is reviewed, which includes the composition-structure-drug delivery relationship and the functional effect on the antibacteria and tissue-stimulation properties. Also, application of different mesoporous materials on construction of 3D macroporous scaffolds for bone tissue engineering was disused. Finally, this review discusses the possibility of covalently grafting different osteoinductive agents to the silica-based mesoporous scaffold surface that act as attracting signals for bone cells to promote the bone regeneration process.

In vitro and in vivo drug release behavior and osteogenic potential of a composite scaffold based on poly(ε-caprolactone)-block-poly(lactic-co-glycolic acid) and β-tricalcium phosphate

To cure serious bone tuberculosis, a novel long-term drug delivery system was designed and prepared to satisfy the needs of both bone regeneration and antituberculous drug therapy.