Engineering a multi-biofunctional composite using poly(ethylenimine) decorated graphene oxide for bone tissue regeneration

Nanotechnology in tissue engineering: expanding possibilities with nanoparticles

Tissue engineering is a multidisciplinary field that merges engineering, material science, and medical biology in order to develop biological alternatives for repairing, replacing, maintaining, or boosting the functionality of tissues and organs. The ultimate goal of tissue engineering is to create biological alternatives for repairing, replacing, maintaining, or enhancing the functionality of tissues and organs. However, the current landscape of tissue engineering techniques presents several challenges, including a lack of suitable biomaterials, inadequate cell proliferation, limited methodologies for replicating desired physiological structures, and the unstable and insufficient production of growth factors, which are essential for facilitating cell communication and the appropriate cellular responses. Despite these challenges, there has been significant progress made in tissue engineering techniques in recent years. Nanoparticles hold a major role within the realm of nanotechnology due to their unique qualities that change with size. These particles, which provide potential solutions to the issues that are met in tissue engineering, have helped propel nanotechnology to its current state of prominence. Despite substantial breakthroughs in the utilization of nanoparticles over the past two decades, the full range of their potential in addressing the difficulties within tissue engineering remains largely untapped. This is due to the fact that these advancements have occurred in relatively isolated pockets. In the realm of tissue engineering, the purpose of this research is to conduct an in-depth investigation of the several ways in which various types of nanoparticles might be put to use. In addition to this, it sheds light on the challenges that need to be conquered in order to unlock the maximum potential of nanotechnology in this area.

Bilayer regenerated cellulose/quaternized chitosan-hyaluronic acid/collagen electrospun scaffold for potential wound healing applications

In this study, a bilayer electrospun scaffold has been prepared using regenerated cellulose (RC)/quaternized chitosan (CS) as the primary layer and collagen/hyaluronic acid (HA) as the second layer. An approximate 48 mol% substituted (estimated from 1H NMR) quaternized CS was used in this study. Both layers were crosslinked with EDC/NHS, reflecting an increase in UTS (2.29 MPa for the bilayer scaffold compared to 1.82 MPa for the RC scaffold). Initial cell viability, cell adhesion and proliferation, FDA staining for live cells, and hydroxyproline release rate from cells were evaluated with L929 mouse fibroblast cells. Also, detailed in vitro studies were performed using HADF cells, which include MTT Assay, Live/Dead imaging, DAPI staining, gene expression of PDGF, VEGF-A, and COL1 in RT-PCR, and cell cycle analysis. The collagen/HA-based bilayer scaffold depicted a 9.76-fold increase of VEGF-A compared to a 2.1-fold increase for the RC scaffold, indicating angiogenesis and vascularization potential. In vitro scratch assay was performed to observe the migration of cells in simulated wounds. Antimicrobial, antioxidant, and protease inhibitory activity were further performed, and overall, the primary results highlighted the potential usage of bilayer scaffold in wound healing applications.

Research advances of nanomaterials for the acceleration of fracture healing

The bone fracture cases have been increasing yearly, accompanied by the increased number of patients experiencing non-union or delayed union after their bone fracture. Although clinical materials facilitate fracture healing (e.g., metallic and composite materials), they cannot fulfill the requirements due to the slow degradation rate, limited osteogenic activity, inadequate osseointegration ability, and suboptimal mechanical properties. Since early 2000, nanomaterials successfully mimic the nanoscale features of bones and offer unique properties, receiving extensive attention. This paper reviews the achievements of nanomaterials in treating bone fracture (e.g., the intrinsic properties of nanomaterials, nanomaterials for bone defect filling, and nanoscale drug delivery systems in treating fracture delayed union). Furthermore, we discuss the perspectives on the challenges and future directions of developing nanomaterials to accelerate fracture healing.

Investigation of Multiple Shape Memory Behaviors, Thermal and Physical Properties of Benzoxazine Blended with Diamino Polysiloxane

In this research, benzoxazine (BA-a) and diamino polysiloxane (PSX750) blends were prepared at 0-50 wt% of BA-a. The interactions between two polymeric components were investigated via a Fourier Transform Infrared Spectrometer (FT-IR). The thermal properties of the blends were also determined with Dynamic Mechanical Analyzer (DMA) and Thermogravimetric Analyzer (TGA). The mechanical properties and shape memory behaviors of the blends were also investigated. The FTIR spectra exhibited the shift of the peak from 1672 to the range of 1634-1637 cm-1, which could be identified as hydrogen bonds between two polymeric domains at the contents from 30 to 50 wt%. The DMA thermograms revealed two glass transition temperatures, which could indicate a partially miscible system. The char yield values were increased, while the decomposition temperatures were decreased with an increasing benzoxazine content. Interestingly, the blends at the contents of 10 and 20 wt% presented dual-shape memory behaviors, whereas triple- or multiple-shape memory behaviors were observed with benzoxazine contents of 30 to 50 wt%. For the high-temperature recovery state, a shape memory ratio of 97.5% with a recovery time of 65 s and a shape fixity ratio of 66.7% was recorded at the content of 50 wt%. For the low-temperature recovery state, a shape recovery ratio of 98.9% was observed at the same content. Moreover, the values of the recovery ratio for four shape-recovery cycles revealed multiple shape memory behaviors with high recovery ratios in the range of 95-98%.

Investigation of physical, mechanical and biological properties of polyhydroxybutyrate-chitosan/graphene oxide nanocomposite scaffolds for bone tissue engineering applications

Mechanical properties appropriate to native tissues, as an essential component in bone tissue engineering scaffolds, plays a significant role in tissue formation. In the current study, Poly-3 hydroxybutyrate-chitosan (PC) scaffolds reinforced with graphene oxide (GO) were made by the electrospinning method. The addition of GO led to a decrease in fibers diameter, an increase in thermal capacity and an improvement in the surface hydrophilicity of nanocomposite scaffolds. A significant increase in the mechanical properties of PC/GO (PCG) nanocomposite scaffolds was achieved due to the inherent strength of GO as well as its uniform dispersion throughout the polymeric matrix owing to hydrogen bonding and polar interactions. Also, lower biological degradation of the scaffolds (~30% in 100 days) due to the presence of GO provides essential mechanical support for bone regeneration. In addition, the bioactivity results showed that GO reinforcement significantly increases the biomineralization on the surface of the scaffolds. Evaluating cell adhesion and proliferation, as well as ALP activity of MG-63 cells on PC and PCG scaffolds indicated the positive effect of GO on scaffolds' biocompatibility. Overall, the improvement of physicochemical, mechanical, and biological properties of GO-reinforced scaffolds shows the potential of PCG nanocomposite scaffolds for bone tissue engineering.

Fabrication of graphene oxide/copper synergistic antibacterial coating for medical titanium substrate

Titanium (Ti) was an excellent medical metal material, but the lack of good antibacterial activity confined its further practical application. To solve this dilemma, a coating containing graphene oxide (GO) and copper (Cu) was prepared on the surface of Ti sheet (Ti/APS/GO/Cu). First, physical sterilization could be carried out through the sharp-edged sheet structure of GO. Second, the oxygen-containing functional group on the surface of GO and the released Cu²⁺ would generate reactive oxygen species for chemical sterilization. The synergistic effect of GO and Cu substantially enhanced the in vitro and in vivo antibacterial property of Ti sheet, thereby reducing bacterial-related inflammation. Quantitatively, the antibacterial rate of Ti/APS/GO/Cu against E. coli or S. aureus reached over 99%. Besides, Ti/APS/GO/Cu showed excellent biocompatibility and no toxicity to cell. Such work developed multiple sterilization avenues to design non-antibiotic, safe and efficient antibacterial implant material for the biomedical domain.

3D Graphene Oxide-Polyethylenimine Scaffolds for Cardiac Tissue Engineering

The development of novel three-dimensional (3D) nanomaterials combining high biocompatibility, precise mechanical characteristics, electrical conductivity, and controlled pore size to enable cell and nutrient permeation is highly sought after for cardiac tissue engineering applications including repair of damaged heart tissues following myocardial infarction and heart failure. Such unique characteristics can collectively be found in hybrid, highly porous tridimensional scaffolds based on chemically functionalized graphene oxide (GO). By exploiting the rich reactivity of the GO's basal epoxydic and edge carboxylate moieties when interacting, respectively, with NH2 and NH3+ groups of linear polyethylenimines (PEIs), 3D architectures with variable thickness and porosity can be manufactured, making use of the layer-by-layer technique through the subsequent dipping in GO and PEI aqueous solutions, thereby attaining enhanced compositional and structural control. The elasticity modulus of the hybrid material is found to depend on scaffold's thickness, with the lowest value of 13 GPa obtained in samples containing the highest number of alternating layers. Thanks to the amino-rich composition of the hybrid and the established biocompatibility of GO, the scaffolds do not exhibit cytotoxicity; they promote cardiac muscle HL-1 cell adhesion and growth without interfering with the cell morphology and increasing cardiac markers such as Connexin-43 and Nkx 2.5. Our novel strategy for scaffold preparation thus overcomes the drawbacks associated with the limited processability of pristine graphene and low GO conductivity, and it enables the production of biocompatible 3D GO scaffolds covalently functionalized with amino-based spacers, which is advantageous for cardiac tissue engineering applications. In particular, they displayed a significant increase in the number of gap junctions compared to HL-1 cultured on CTRL substrates, which render them key components for repairing damaged heart tissues as well as being used for 3D in vitro cardiac modeling investigations.

Graphene oxide disruption of homeostasis and regeneration processes in freshwater planarian Dugesia japonica via intracellular redox deviation and apoptosis

The aquatic system is a major sink for engineered nanomaterials released into the environment. Here, we assessed the toxicity of graphene oxide (GO) using the freshwater planarian Dugesia japonica, an invertebrate model that has been widely used for studying the effects of toxins on tissue regeneration and neuronal development. GO not only impaired the growth of normal (homeostatic) worms, but also inhibited the regeneration processes of regenerating (amputated) worms, with LC₁₀ values of 9.86 mg/L and 9.32 mg/L for the 48-h acute toxicity test, respectively. High concentration (200 mg/L) of GO killed all the worms after 3 (regenerating) or 4 (homeostasis) days of exposure. Whole-mount in situ hybridization (WISH) and immunofluorescence analyses suggest GO impaired stem cell proliferation and differentiation, and subsequently caused cell apoptosis and oxidative DNA damage during planarian regeneration. Mechanistic analysis suggests that GO disturbed the antioxidative system (enzymatic and non-enzymatic) and energy metabolism in the planarian at both molecular and genetic levels, thus causing reactive oxygen species (ROS) over accumulation and oxidative damage, including oxidative DNA damage, loss of mitochondrial membrane integrity, lack of energy supply for cell differentiation and proliferation leading to retardance of neuron regeneration. The intrinsic oxidative potential of GO contributes to the GO-induced toxicity in planarians. These data suggest that GO in aquatic systems can cause oxidative stress and neurotoxicity in planarians. Overall, regenerated tissues are more sensitive to GO toxicity than homeostatic ones, suggesting that careful handling and appropriate decisions are needed in the application of GO to achieve healing and tissue regeneration.

Synthetic electrospun nanofibers as a supportive matrix in osteogenic differentiation of induced pluripotent stem cells

Continuous remodeling is not able to repair large bone defects. Bone tissue engineering is aimed to repair these defects by creating bone grafts. To do this, several technologies and biomaterials have been employed to fabricate an in vivo-like supportive matrix. Electrospinning is a versatile technique to fabricate porous matrices with interconnected pores and high surface area, replicating in vivo microenvironment. Electrospun scaffolds have been used in a large number of studies to provide a matrix for bone regeneration and osteogenic differentiation of stem cells such as induced pluripotent stem cells (iPSCs). Electrospinning uses both natural and synthetic polymers, either alone or in combination, to fabricate scaffolds. Among them, synthetic polymers have had a great promise in bone regeneration and repair. They allow the fabrication of biocompatible and biodegradable scaffolds with high mechanical properties, suitable for bone engineering. Furthermore, several attempts have done to increase the osteogenic properties of these scaffolds. This paper reviewed the potential of synthetic electrospun scaffolds in osteogenic differentiation of iPSCs. In addition, the approaches to improve the osteogenic differentiation of these scaffolds are addressed.

Bovine serum albumin-functionalized graphene-decorated strontium as a potent complex nanoparticle for bone tissue engineering

Graphene and its family have a great potential in tissue engineering because of their super mechanical properties, electrical conductivity and antibacterial properties. Considering other properties of graphene such as high surface area and ready-to-use functionalization according to the high oxygen-containing groups in graphene oxide family, some needs could be addressed in bone tissue engineering. Herein, we synthesized and decorated strontium nanoparticles (SrNPs) during the reduction process of graphene oxide using green and novel method. Without using hydrazine or chemical linkers, strontium NPs were synthesized and decorated on the surface of rGO simultaneously using BSA. The results of the UV–Vis, FTIR and Raman spectroscopy demonstrated that BSA could successfully reduce graphene oxide and decorated SrNPs on the surface of rGO. FESEM and TEM exhibited that in situ synthesized SrNPs had 25–30 nm diameter. Interestingly, cell viability for MC3T3-E1 cells treated with SrNPs-rGO, were significantly higher than BSA-rGO and GO in constant concentration. Furthermore, we investigated the alkaline phosphatase activity (ALP) of these nanosheets that the results demonstrated Sr-BSA-rGO enhanced ALP activity more than GO and BSA-rGO. Remarkably, the relative expression of RUNX 2 and Col1 genes of MC3T3-E1 cells was boosted when treated with Sr-BSA-rGO nanosheets. This study revealed that using proteins and other biomolecules as green and facile agent for decoration of smart nanoparticles on the surface of nanosheets, would be promising and assist researcher to replace the harsh and toxic hydrazine like materials with bio-friendly method. These results demonstrated that Sr-BSA-rGO had the excellent capability for regenerating bone tissue and could be used as an osteogenesis booster in implants.

Comparison of Hydroxyapatite/Poly(lactide-co-glycolide) and Hydroxyapatite/Polyethyleneimine Composite Scaffolds in Bone Regeneration of Swine Mandibular Critical Size Defects: In Vivo Study

Reconstruction of jaw bone defects present a significant problem because of specific aesthetic and functional requirements. Although widely used, the transplantation of standard autograft and allograft materials is still associated with significant constraints. Composite scaffolds, combining advantages of biodegradable polymers with bioceramics, have potential to overcome limitations of standard grafts. Polyethyleneimine could be an interesting novel biocompatible polymer for scaffold construction due to its biocompatibility and chemical structure. To date, there have been no in vivo studies assessing biological properties of hydroxyapatite bioceramics scaffold modified with polyethyleneimine. The aim of this study was to evaluate in vivo effects of composite scaffolds of hydroxyapatite ceramics and poly(lactide-co-glycolide) and novel polyethyleneimine on bone repair in swine’s mandibular defects, and to compare them to conventional bone allograft (BioOss). Scaffolds were prepared using the method of polymer foam template in three steps. Pigs, 3 months old, were used and defects were made in the canine, premolar, and molar area of their mandibles. Four months following the surgical procedure, the bone was analyzed using radiological, histological, and gene expression techniques. Hydroxyapatite ceramics/polyethyleneimine composite scaffold demonstrated improved biological behavior compared to conventional allograft in treatment of swine’s mandibular defects, in terms of bone density and bone tissue histological characteristics.

Emerging zero-dimensional to four-dimensional biomaterials for bone regeneration

Bone is one of the most sophisticated and dynamic tissues in the human body, and is characterized by its remarkable potential for regeneration. In most cases, bone has the capacity to be restored to its original form with homeostatic functionality after injury without any remaining scarring. Throughout the fascinating processes of bone regeneration, a plethora of cell lineages and signaling molecules, together with the extracellular matrix, are precisely regulated at multiple length and time scales. However, conditions, such as delayed unions (or nonunion) and critical-sized bone defects, represent thorny challenges for orthopedic surgeons. During recent decades, a variety of novel biomaterials have been designed to mimic the organic and inorganic structure of the bone microenvironment, which have tremendously promoted and accelerated bone healing throughout different stages of bone regeneration. Advances in tissue engineering endowed bone scaffolds with phenomenal osteoconductivity, osteoinductivity, vascularization and neurotization effects as well as alluring properties, such as antibacterial effects. According to the dimensional structure and functional mechanism, these biomaterials are categorized as zero-dimensional, one-dimensional, two-dimensional, three-dimensional, and four-dimensional biomaterials. In this review, we comprehensively summarized the astounding advances in emerging biomaterials for bone regeneration by categorizing them as zero-dimensional to four-dimensional biomaterials, which were further elucidated by typical examples. Hopefully, this review will provide some inspiration for the future design of biomaterials for bone tissue engineering.

Surface Decoration of Redox-Modulating Nanoceria on 3D-Printed Tissue Scaffolds Promotes Stem Cell Osteogenesis and Attenuates Bacterial Colonization

Oxidative stress at the bone defect site delays the bone regeneration process. Increased level of reactive oxygen species (ROS) is the primary cause of oxidative stress at the damaged site. Bone tissue scaffolds that scavenge ROS offer a potential and yet unexplored route for faster bone healing. Cerium oxide (ceria) is known for its redox-modulating behavior. Three-dimensional (3D)-printed porous scaffolds fabricated from degradable polymers provide a physical microenvironment but lack the bioactivity for tissue regeneration. In this work, porous poly(lactic acid) (PLA) scaffolds were prepared by 3D printing and modified with poly(ethylene imine) and citric acid to decorate with ceria nanoparticles. Scanning electron micrographs revealed a macroporous architecture decorated with ceria particles. The compressive modulus of 27 MPa makes them suitable for trabecular bone. The scaffolds supported human mesenchymal stem cell growth, confirming cytocompatibility. The ability to scavenge ROS confirmed that surface functionalization with ceria could reduce oxidative stress levels in the cells. Stem cell osteogenesis was enhanced after ceria decoration of the PLA scaffolds. Transcriptional profiling studied by sequencing revealed changes in the expression of genes associated with inflammation and cell-material interactions. The ceria-functionalized scaffolds show enhanced antibacterial activity against both Gram-negative and Gram-positive bacterial strains. These results demonstrate that surface decoration with nanoceria offers a viable route for enhancing the bioactivity of 3D-printed PLA scaffolds for bone tissue regeneration with ROS scavenging and antibacterial capability.

GO-based antibacterial composites: Application and design strategies

Graphene oxide (GO), for its unique structure with high biocompatibility and designability, is widely used in the antibacterial field. Various strategies have been designed to fabricate GO-based composites with antibacterial properties. This review summarized these strategies, divided them into three types and interpreted their antibacterial mechanisms: (i) "GO*/non-GO" type in which GO acts as the single antibacterial core, (ii) "GO*/non-GO*" type in which GO and non-GO components function synergistically as dual antibacterial cores, (iii) "GO/non-GO*" type in which non-GO acts as the single antibacterial core, while GO component plays a supportive, not a dominant role in antibiosis. Besides, the fields suiting their applications and factors influencing their antibacterial properties were analyzed. Finally, the limitations and prospects in the current researches were discussed. In summary, GO-based composites have revolutionized antibacterial strategies. This review may serve as a reference to inspire further research on GO-based antibacterial composites.

Graphene and its Derivatives for Bone Tissue Engineering: In Vitro and In Vivo Evaluation of Graphene-Based Scaffolds, Membranes and Coatings

Bone regeneration or replacement has been proved to be one of the most effective methods available for the treatment of bone defects caused by different musculoskeletal disorders. However, the great contradiction between the large demand for clinical therapies and the insufficiency and deficiency of natural bone grafts has led to an urgent need for the development of synthetic bone graft substitutes. Bone tissue engineering has shown great potential in the construction of desired bone grafts, despite the many challenges that remain to be faced before safe and reliable clinical applications can be achieved. Graphene, with outstanding physical, chemical and biological properties, is considered a highly promising material for ideal bone regeneration and has attracted broad attention. In this review, we provide an introduction to the properties of graphene and its derivatives. In addition, based on the analysis of bone regeneration processes, interesting findings of graphene-based materials in bone regenerative medicine are analyzed, with special emphasis on their applications as scaffolds, membranes, and coatings in bone tissue engineering. Finally, the advantages, challenges, and future prospects of their application in bone regenerative medicine are discussed.

Bioinspired Graphene Oxide Membranes with pH-Responsive Nanochannels for High-Performance Nanofiltration

Tunable gating graphene oxide (GO) membranes with high water permeance and precise molecular separation remain highly desired in smart nanofiltration devices. Herein, bioinspired by the filtration function of the renal glomerulus, we report a smart and high-performance graphene oxide membrane constructed via introducing positively charged polyethylenimine-grafted GO (GO-PEI) to negatively charged GO nanosheets. It was found that the additional GO-PEI component changed the surface charge, improved the hydrophilicity, and enlarged the nanochannels. The glomerulus-inspired graphene oxide membrane (G-GOM) shows a water permeance up to 88.57 L m^-2 h^-1 bar^-1, corresponding to a 4 times enhancement compared with that of a conventional GO membrane due to the enlarged confined nanochannels. Meanwhile, owing to the electrostatic interaction, it can selectively remove positively charged methylene blue at pH 12 and negatively charged methyl orange at pH 2, with a removal rate of over 96%. The high and cyclic water permeance and highly selective organic removal performance can be attributed to the synergic effect of controlled nanochannel size and tunable electrostatic interaction in responding to the environmental pH. This strategy provides insight into designing pH-responsive gating membranes with tunable selectivity, representing a great advancement in smart nanofiltration with a wide range of applications.

Improved Mechanical, Anti-UV Irradiation, and Imparted Luminescence Properties of Cyanate Ester Resin/Unzipped Multiwalled Carbon Nanotubes/Europium Nanocomposites

Cyanate ester resin (CER) is an excellent thermal stable polymer. However, its mechanical properties are not appropriate for its application, with brittle weakness, and it has poor functional properties, such as luminescence. This work innovatively combines the luminescence property and the improved mechanical properties with the inherent thermal property of cyanate ester. A novel nanocomposite, CER/uMWCNTs/Eu, with multi-functional properties, has been prepared. The results show that with the addition of 0.1 wt.% of uMWCNTs to the resin, the flexural strength and tensile strength increased 59.3% and 49.3%, respectively. As the curing process of the CER progresses, the injected luminescence signal becomes luminescence behind the visible (FBV). The luminescence intensity of CER/uMWCNTs/Eu was much stronger than that of CER/MWCNTs/Eu, and the luminescence lifetime of CER/MWCNTs/Eu and CER/uMWCNTs/Eu was 8.61 μs and 186.39 μs, respectively. FBV exhibited great potential in the embedment of photon quantum information. Therefore, it can be predicted that CER/uMWCNTs/Eu composites will not only have a wide range of applications in sensing, detection, and other aspects, but will also exhibit great potential in the embedding of photon quantum information.

Applications of nanomaterials in tissue engineering

Recent advancement in nanotechnology has brought prominent benefits in tissue engineering, which has been used to repair or reconstruct damaged tissues or organs and design smart drug delivery systems. With numerous applications of nanomaterials in tissue engineering, it is vital to choose appropriate nanomaterials for different tissue engineering applications because of the tissue heterogeneity. Indeed, the use of nanomaterials in tissue engineering is directly determined by the choice. In this review, we mainly introduced the use of nanomaterials in tissue engineering. First, the basic characteristics, preparation and characterization methods of the types of nanomaterials are introduced briefly, followed by a detailed description of the application and research progress of nanomaterials in tissue engineering and drug delivery. Finally, the existing challenges and prospects for future applications of nanomaterials in tissue engineering are discussed.

Scientific description about the types, synthesis, functionalization, characterization application, challenges and prospects of nanomaterials in tissue engineering.

Molecular Control of Interfacial Fibronectin Structure on Graphene Oxide Steers Cell Fate

The use of graphene-based materials (GBMs) for tissue-engineering applications has been growing exponentially because of the seemingly endless multifunctional and tunable physicochemical properties of graphene that can be exploited to influence cellular behavior. Despite many demonstrations wherein cell physiology has been modulated on different GBMs, a clear mechanism connecting the different physicochemical properties of GBMs to cell fate has remained elusive. In this work, we demonstrate how different GBMs can be used to bias cell fate in a multiscale study-starting from serum protein (fibronectin) adsorption and its molecular scale morphology, structure, and bioactivity and ending with stem cell response. Using heat to chemically reduce graphene oxide without changing physical properties, we show that graphene chemistry controls surface-adsorbed molecular conformation and morphology, epitope presentation, and stem cell attachment. Moreover, this subtle change in the protein structure was found to drive increased bone differentiation of stem cells, suggesting that the physicochemical properties of graphene biases cell fate by directly influencing the adsorbed protein structure and subsequent biochemical activity.

Graphene Oxide Coatings as Tools to Prevent Microbial Biofilm Formation on Medical Device

The clinical challenge on surface engineering of medical devices to prevent microorganisms adhesion and biofilm formation, has become an essential aspect for medical implants. Antibacterial properties of Graphene Oxide (GO) have been demonstrated across a broad spectrum of bacteria, and the different mechanisms of action with which this nanomaterial interacts with the microbial surface have been elucidated in detail. Innovative protective coatings based on graphene film and hydrogel could represent an innovative solution for the prevention of nosocomial pathogens colonization on implantable device. This brief review mainly focuses on the applications of graphene in nanomedicine with a particular deepening on the antibacterial properties of GO and GO-based nanomaterials. In order to evaluate the possible future applications of GO as an anti-biofilm coating material for medical devices, studies on the ability of graphene coated surface to prevent microbial adhesion are also discussed. A concise review on in vitro toxicity and in vivo safety is also presented.

Advances in Biodegradable 3D Printed Scaffolds with Carbon-Based Nanomaterials for Bone Regeneration

Bone possesses an inherent capacity to fix itself. However, when a defect larger than a critical size appears, external solutions must be applied. Traditionally, an autograft has been the most used solution in these situations. However, it presents some issues such as donor-site morbidity. In this context, porous biodegradable scaffolds have emerged as an interesting solution. They act as external support for cell growth and degrade when the defect is repaired. For an adequate performance, these scaffolds must meet specific requirements: biocompatibility, interconnected porosity, mechanical properties and biodegradability. To obtain the required porosity, many methods have conventionally been used (e.g., electrospinning, freeze-drying and salt-leaching). However, from the development of additive manufacturing methods a promising solution for this application has been proposed since such methods allow the complete customisation and control of scaffold geometry and porosity. Furthermore, carbon-based nanomaterials present the potential to impart osteoconductivity and antimicrobial properties and reinforce the matrix from a mechanical perspective. These properties make them ideal for use as nanomaterials to improve the properties and performance of scaffolds for bone tissue engineering. This work explores the potential research opportunities and challenges of 3D printed biodegradable composite-based scaffolds containing carbon-based nanomaterials for bone tissue engineering applications.

Mimicking the electrophysiological microenvironment of bone tissue using electroactive materials to promote its regeneration

The process of bone tissue repair and regeneration is complex and requires a variety of physiological signals, including biochemical, electrical and mechanical signals, which collaborate to ensure functional recovery. The inherent piezoelectric properties of bone tissues can convert mechanical stimulation into electrical effects, which play significant roles in bone maturation, remodeling and reconstruction. Electroactive materials, including conductive materials, piezoelectric materials and electret materials, can simulate the physiological and electrical microenvironment of bone tissue, thereby promoting bone regeneration and reconstruction. In this paper, the structures and performances of different types of electroactive materials and their applications in the field of bone repair and regeneration are reviewed, particularly by providing the results from in vivo evaluations using various animal models. Their advantages and disadvantages as bone repair materials are discussed, and the methods for tuning their performances are also described, with the aim of providing an up-to-date account of the proposed topics.

Anti-tumor effects of Artemisia nilagirica extract on MDA-MB-231 breast cancer cells: deciphering the biochemical and biomechanical properties via TGF-β upregulation

Purpose

Artemisia nilagirica (AN), which is known to have antimicrobial, antioxidant, antiulcer, and anti-asthmatic properties, has been recently shown to have anti-cancer activity. However, the mechanism responsible for the anti-cancer property and its effect on cellular properties and functions are not known.

Material and methods

We have characterized the biochemical and biomechanical properties of MDA-MB-231 cells treated with the methanolic extract from AN.

Results

We show that AN-treatment decreases cell-eccentricity, increases expression of actin and microtubules, and do not affect cell-area. Increased expression of cytoskeletal proteins is known to change the mechanical properties of the cells, which was confirmed using micropipette aspiration and Atomic Force Microscopy. We identified the upregulation of the tumorigenic pathway (TGF-β) leading to activation of Rho-A as the molecular mechanism responsible for actin upregulation. Since the initial stages of TGF-β upregulation are known to suppress tumor growth by activating apoptosis, we hypothesized that the mechanism of cell death due to AN-treatment is through TGF-β activation. We have validated this hypothesis by partially recuing cell death through inhibition of TGF-β using Alk-5.

Conclusion

In summary, our study reveals the mechanism of action of Artemisia nilagirica using a synergy between biochemical and biomechanical techniques.

Injectable thermosensitive hybrid hydrogel containing graphene oxide and chitosan as dental pulp stem cells scaffold for bone tissue engineering

Here, we fabricated thermosensitive injectable hydrogel containing poly (N-isopropylacrylamide) (PNIPAAm)-based copolymer/graphene oxide (GO) composite with different feed ratio to chitosan (CS) as a natural polymer through physical and chemical crosslinking for the proliferation and differentiation of the human dental pulp stem cells (hDPSCs) to the osteoblasts. The PNIPAAm copolymer/GO composite was synthesized by free-radical copolymerization of (N-isopropylacrylamide) (NIPAAm), itaconic acid (IA) and maleic anhydride-modified poly(ethylene glycol) (PEG) in the presence of GO and used for the preparation of the hydrogels. The formulated hydrogels were evaluated for the porous architecture, rheological behavior, compressive strength, swelling property, in vitro degradation, hemocompatibility, biocompatibility, and differentiation. The hydrogel could enhance the deposition of minerals and the activity of alkaline phosphatase (ALP), in large part attributable to the oxygen and amine-containing functional groups of GO and CS. The engineered hydrogel could also upregulate the expression of the Runt-related transcription factor 2 and osteocalcin in the hDPSCs cultivated in both the normal and osteogenic media. It seems to promote the absorption of osteogenic inducer too. Based on our findings, the engineered hydrogel demonstrated the osteogenic potential, upon which it is proposed as a constructing scaffold in bone tissue engineering for the transplantation of hDPSCs.

Application of BMP-2/FGF-2 gene-activated scaffolds for dental pulp capping

OBJECTIVES

To evaluate the effect of non-viral gene therapy on human dental pulp stem cells (DPSCs) in an in vitro and an ex vivo model.

MATERIALS AND METHODS

Nanoplexes comprising polyethyleneimine (PEI) and plasmid DNA (pDNA) encoding for fibroblast growth factor-2 (pFGF-2) and bone morphogenic protein-2 (pBMP-2) were cultured with DPSCs to evaluate cytotoxicity, protein expression, and mineralization activity. Collagen scaffolds loaded with these nanoplexes or mineral trioxide aggregate (MTA) were utilized in an ex vivo tooth culture model to assess pulp response, over a period of 14 days. All nanoplex formulations were characterized for size and zeta potential by measuring dynamic light scattering and electrophoretic mobility, respectively.

RESULTS

DPSCs treated with the nanoplexes showed increased cell proliferation and enhanced expression of BMP-2 and FGF-2 proteins. Collagen scaffolds containing PEI-pBMP-2 and/or pFGF-2 nanoplexes significantly increased cell proliferation, BMP-2 and FGF-2 expression, and mineralization when compared to MTA. Ex vivo histology showed a well-preserved pulp and healthy tissue in both the MTA and scaffold groups. Connective tissue in contact with the scaffold was dense and homogeneous, with some cells present in contact and within the scaffold.

CONCLUSION

Transfection of DPSCs with pBMP-2/pFGF-2 nanoplexes resulted in increased expression of BMP-2 and FGF-2, enhanced proliferation, and mineralization properties compared to MTA. These findings were supported by the ex vivo observations.

CLINICAL RELEVANCE

This biological approach in pulp capping brings new insights into the effective management of engineered pulp tissues, mainly those generated by the transplantation of DPSCs in empty root canals.

Bone Tissue Engineering via Carbon-Based Nanomaterials

Bone tissue engineering (BTE) has received significant attention due to its enormous potential in treating critical-sized bone defects and related diseases. Traditional materials such as metals, ceramics, and polymers have been widely applied as BTE scaffolds; however, their clinical applications have been rather limited due to various considerations. Recently, carbon-based nanomaterials attract significant interests for their applications as BTE scaffolds due to their superior properties, including excellent mechanical strength, large surface area, tunable surface functionalities, high biocompatibility as well as abundant and inexpensive nature. In this article, recent studies and advancements on the use of carbon-based nanomaterials with different dimensions such as graphene and its derivatives, carbon nanotubes, and carbon dots, for BTE are reviewed. Current challenges of carbon-based nanomaterials for BTE and future trends in BTE scaffolds development are also highlighted and discussed.

Linking graphene-based material physicochemical properties with molecular adsorption, structure and cell fate

Graphene, an allotrope of carbon, consists of a single layer of carbon atoms with uniquely tuneable properties. As such, graphene-based materials (GBMs) have gained interest for tissue engineering applications. GBMs are often discussed in the context of how different physicochemical properties affect cell physiology, without explicitly considering the impact of adsorbed proteins. Establishing a relationship between graphene properties, adsorbed proteins, and cell response is necessary as these proteins provide the surface upon which cells attach and grow. This review highlights the molecular adsorption of proteins on different GBMs, protein structural changes, and the connection to cellular function.

Silica-Coated Magnetic Iron Oxide Nanoparticles Grafted onto Graphene Oxide for Protein Isolation

In this study, silica-coated magnetic iron oxide nanoparticles (MNPs@SiO2) were covalently conjugated onto graphene oxide (GO/MNP@SiO2) for protein isolation. First, MNPs were precisely coated with a silica layer on the surface by using the reverse microemulsion method, followed by incubation with 3-glycidyloxypropyltrimethoxysilane (GPTS) to produce the GPTS-functionalized MNPs@SiO2 (GPTS-coated MNPs@SiO2) that display epoxy groups on the surface. The silica shell on the MNPs was optimized at 300 µL of Igepal®CO-520, 5 mg of MNP, 100 µL of TEOS, 100 µL of NH4OH and 3% of 3-glycidyloxypropyltrimethoxysilane (GPTS). Simultaneously, polyethyleneimine (PEI) was covalently conjugated to GO to enhance the stability of GO in aqueous solutions and create the reaction sites with epoxy groups on the surface of GPTS-coated MNP@SiO2. The ratio of PEI grafted GO and GPTS-coated MNP@SiO2 (GO/MNP ratio) was investigated to produce GO/MNPs@SiO2 with highly saturated magnetization without aggregation. As a result, the GO/MNP ratio of 5 was the best condition to produce the GO/MNP@SiO2 with 9.53 emu/g of saturation superparamagnetization at a magnetic field of 2.0 (T). Finally, the GO/MNPs@SiO2 were used to separate bovine serum albumin (BSA) to investigate its protein isolation ability. The quantity of BSA adsorbed onto 1 mg of GO/MNP@SiO2 increased sharply over time to reach 628 ± 9.3 µg/mg after 15 min, which was 3.5-fold-higher than that of GPTS-coated MNP@SiO2. This result suggests that the GO/MNP@SiO2 nanostructure can be used for protein isolation.

Enhancing the antivirus activity of chimeric canine interferon with ricin subunit B by using nanoparticle formulations

Despite interferon alpha having a broad spectrum of antiviral activity and strong antiproliferative activity, its applications are severely limited due to the intrinsic properties of proteins, such as poor stability and short serum half-life. In our study, canine interferon alpha (CaIFNα) gene was fused with the ricin toxin B chain (RTB) to form rCaIFNα/RTB, which encodes a 463-amino acid protein containing a 15-amino acid encoded (G₄S)₃ flexible linker. After expression in prokaryote, purification and renaturation, the cytotoxicity and antiviral activity of rCaIFNα/RTB were investigated in Madin–Darby canine kidney (MDCK) cells. rCaIFNα/RTB exerted a superior anti-vesicular stomatitis virus (VSV) activity on MDCK cells. Furthermore, we have developed a nanoparticle formulation of rCaIFNα/RTB by using polyethylenimine (PEI) through electrostatic interaction. rCaIFNα/RTB@PEI₁₀₀₀₀ is more stable than rCaIFNα/RTB at various pH and temperature levels, and it possesses enhanced antiviral activity. Our findings facilitate further research on the role of type I IFN in antiviral defense responses in Canis lupus familiaris.

Despite interferon alpha having a broad spectrum of antiviral activity and strong antiproliferative activity, its applications are severely limited due to the intrinsic properties of proteins, such as poor stability and short serum half-life.

A nanopillar array on black titanium prepared by reactive ion etching augments cardiomyogenic commitment of stem cells

A major impediment in the clinical translation of stem cell therapy has been the inability to efficiently and reproducibly direct differentiation of a large population of stem cells. Thus, we aimed to engineer a substrate for culturing stem cells to efficiently induce cardiomyogenic lineage commitment. In this work, we present a nanopillar array on the surface of titanium that was prepared by mask-less reactive ion etching. Scanning electron and atomic force microscopy revealed that the surface was covered by vertically aligned nanopillars each of ≈1 μm with a diameter of ≈80 nm. The nanopillars supported the attachment and proliferation of human mesenchymal stem cells (hMSCs). Cardiomyogenic lineage commitment of the stem cells was more enhanced on the nanopillars than on the smooth surface. When co-cultured with neonatal rat cardiomyocytes, the cyclic pattern of calcium transport observed distinctly in cells differentiated on the arrays compared to the cells cultured on the smooth surface was the functional validation of differentiation. The use of small molecule inhibitors revealed that integrins namely, α₂β₁ and α_vβ₃, are essential for cardiomyogenesis on the nanostructured surface, which is further mediated by FAK, Erk and Akt cell signaling pathways. This study demonstrates that the nanopillar array efficiently promotes the cardiomyogenic lineage commitment of stem cells via integrin-mediated signaling and can potentially serve as a platform for the ex vivo differentiation of stem cells toward cell therapy in cardiac tissue repair and regeneration.

Functionalization of Carbon Nanomaterials for Biomedical Applications

Over the past decade, carbon nanostructures (CNSs) have been widely used in a variety of biomedical applications. Examples are the use of CNSs for drug and protein delivery or in tools to locally dispense nucleic acids to fight tumor affections. CNSs were successfully utilized in diagnostics and in noninvasive and highly sensitive imaging devices thanks to their optical properties in the near infrared region. However, biomedical applications require a complete biocompatibility to avoid adverse reactions of the immune system and CNSs potentials for biodegradability. Water is one of the main constituents of the living matter. Unfortunately, one of the disadvantages of CNSs is their poor solubility. Surface functionalization of CNSs is commonly utilized as an efficient solution to both tune the surface wettability of CNSs and impart biocompatible properties. Grafting functional groups onto the CNSs surface consists in bonding the desired chemical species on the carbon nanoparticles via wet or dry processes leading to the formation of a stable interaction. This latter may be of different nature as the van Der Waals, the electrostatic or the covalent, the π-π interaction, the hydrogen bond etc. depending on the process and on the functional molecule at play. Grafting is utilized for multiple purposes including bonding mimetic agents such as polyethylene glycol, drug/protein adsorption, attaching nanostructures to increase the CNSs opacity to selected wavelengths or provide magnetic properties. This makes the CNSs a very versatile tool for a broad selection of applications as medicinal biochips, new high-performance platforms for magnetic resonance (MR), photothermal therapy, molecular imaging, tissue engineering, and neuroscience. The scope of this work is to highlight up-to-date using of the functionalized carbon materials such as graphene, carbon fibers, carbon nanotubes, fullerene and nanodiamonds in biomedical applications.

Carbon based nanomaterials for tissue engineering of bone: Building new bone on small black scaffolds: A review

Tissue engineering is a rapidly-growing approach to replace and repair damaged and defective tissues in the human body. Every year, a large number of people require bone replacements for skeletal defects caused by accident or disease that cannot heal on their own. In the last decades, tissue engineering of bone has attracted much attention from biomedical scientists in academic and commercial laboratories. A vast range of biocompatible advanced materials has been used to form scaffolds upon which new bone can form. Carbon nanomaterial-based scaffolds are a key example, with the advantages of being biologically compatible, mechanically stable, and commercially available. They show remarkable ability to affect bone tissue regeneration, efficient cell proliferation and osteogenic differentiation. Basically, scaffolds are templates for growth, proliferation, regeneration, adhesion, and differentiation processes of bone stem cells that play a truly critical role in bone tissue engineering. The appropriate scaffold should supply a microenvironment for bone cells that is most similar to natural bone in the human body. A variety of carbon nanomaterials, such as graphene oxide (GO), carbon nanotubes (CNTs), fullerenes, carbon dots (CDs), nanodiamonds and their derivatives that are able to act as scaffolds for bone tissue engineering, are covered in this review. Broadly, the ability of the family of carbon nanomaterial-based scaffolds and their critical role in bone tissue engineering research are discussed. The significant stimulating effects on cell growth, low cytotoxicity, efficient nutrient delivery in the scaffold microenvironment, suitable functionalized chemical structures to facilitate cell-cell communication, and improvement in cell spreading are the main advantages of carbon nanomaterial-based scaffolds for bone tissue engineering.

Developing a Strontium-Releasing Graphene Oxide-/Collagen-Based Organic-Inorganic Nanobiocomposite for Large Bone Defect Regeneration via MAPK Signaling Pathway

Significant efforts have been dedicated to fabricating favorable biomaterial-based bone substitutes for the repair of large bone defects. However, the development of bone biomaterials with suitable physiochemical and osteoinductive properties remains a challenge. Here, novel strontium-graphene oxide (Sr-GO) nanocomposites that allow long-term release of Sr ions are fabricated, which are used to reinforce collagen (Col) scaffolds through covalent cross-linking. The prepared Sr-GO-Col scaffold demonstrates significantly high water retention rates and excellent mechanical properties compared with unmodified Col scaffolds. The Sr-GO-modified Col scaffolds display a strong effect on adipose-derived stem cells by facilitating cell adhesion and osteogenic differentiation and by promoting the secretion of angiogenic factors to stimulate the in vitro tube formation of endothelial cells. Additionally, the secretion of angiogenic VEGF and osteogenic BMP-2 proteins is increased, which may be attributed to the synergistic effects of GO and Sr on the activation of the MAPK signaling pathway. The Sr-GO-Col constructs were then transplanted into rat critical-size calvarial bone defects, which showed the best bone regeneration and angiogenesis outcome at 12 weeks. Moreover, histological staining results show that the Sr-GO-Col group achieved complete defect bridging with the newly formed bone tissue and the residual Sr-GO nanoparticles are phagocytosed and degraded by multinucleated giant cells. These findings reveal that the incorporation of inorganic Sr-GO nanocomposites into biocompatible Col scaffolds is a viable strategy for fabricating favorable substitutes that enhance the regeneration of large bone defects.

Stimuli-Responsive Graphene Nanohybrids for Biomedical Applications

Stimuli-responsive materials, also known as smart materials, can change their structure and, consequently, original behavior in response to external or internal stimuli. This is due to the change in the interactions between the various functional groups. Graphene, which is a single layer of carbon atoms with a hexagonal morphology and has excellent physiochemical properties with a high surface area, is frequently used in materials science for various applications. Numerous surface functionalizations are possible for the graphene structure with different functional groups, which can be used to alter the properties of native materials. Graphene-based hybrids exhibit significant improvements in their native properties. Since functionalized graphene contains several reactive groups, the behavior of such hybrid materials can be easily tuned by changing the external conditions, which is very useful in biomedical applications. Enhanced cell proliferation and differentiation of stem cells was reported on the surfaces of graphene-based hybrids with negligible cytotoxicity. In addition, pH or light-induced drug delivery with a controlled release rate was observed for such nanohybrids. Besides, notable improvements in antimicrobial activity were observed for nanohybrids, which demonstrated their potential for biomedical applications. This review describes the physiochemical properties of graphene and graphene-based hybrid materials for stimuli-responsive drug delivery, tissue engineering, and antimicrobial applications.

Bacteria Death and Osteoblast Metabolic Activity Correlated to Hydrothermally Synthesised TiO₂ Surface Properties

Orthopaedic surgery comes with an inherent risk of bacterial infection, prolonged antibiotic therapy and revision surgery. Recent research has focused on nanostructured surfaces to improve the bactericidal and osseointegrational properties of implants. However, an understanding of the mechanical properties of bactericidal materials is lacking. In this work, the surface properties of hydrothermal TiO₂ nanostructured surfaces are investigated for their effect on bactericidal efficiency and cellular metabolic activity of human osteoblast cells. TiO₂ nanostructures, approximately 307 nm in height and 14 GPa stiffness, were the most effective structures against both gram-positive (Staphylococcus aureus) and gram-negative (Pseudomonas aeruginosa) bacteria. Statistical analysis significantly correlated structure height to the death of both bacteria strains. In addition, the surface contact angle and Young’s modulus were correlated to osteoblast metabolic activity. Hydrophilic surfaces with a contact angle between 35 and 50° produced the highest cellular metabolic activity rates after 24 h of incubation. The mechanical tests showed that nanostructures retain their mechanical stability and integrity over a long time-period, reaffirming the surfaces’ applicability for implants. This work provides a thorough examination of the surface, mechanical and wettability properties of multifunctional hydrothermally synthesised nanostructured materials, capable of killing bacteria whilst improving osteoblast metabolic rates, leading to improved osseointegration and antibacterial properties of orthopaedic implants.

Egg shell-derived calcium phosphate/carbon dot nanofibrous scaffolds for bone tissue engineering: Fabrication and characterization

Recent exciting findings of the particular properties of Carbon dot (CDs) have shed light on potential biomedical applications of CDs-containing composites. While CDs so far have been widely used as biosensors and bioimaging agents, in the present study for the first time, we evaluate the osteoconductivity of CDs in poly (ε-caprolactone) (PCL)/polyvinyl alcohol (PVA) [PCL/PVA] nanofibrous scaffolds. Moreover, further studies were performed to evaluate egg shell-derived calcium phosphate (TCP3) and its cellular responses, biocompatibility and in vitro osteogenesis. Scaffolds were fabricated by simultaneous electrospinning of PCL with three different types of calcium phosphate, PVA and CDs. Fabricated scaffolds were characterized by Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), contact angle measurement and degradation assessment. SEM, the methyl thiazolyl tetrazolium (MTT) assay, and alkaline phosphatase (ALP) activity test were performed to evaluate cell morphology, proliferation and osteogenic differentiation, respectively. The results demonstrated that while the addition of just 1 wt% CDs and TCP3 individually into PCL/PVA nanocomposite enhanced ALP activity and cell proliferation rate (p < 0.05), the synergetic effect of CDs/TCP3 led to highest osteogenic differentiation and proliferation rate compared to other scaffolds (p < 0.05). Hence, CDs and PCL/PVA-TCP3 could serve as a potential candidate for bone tissue regeneration.

In vitro osteogenic differentiation potential of the human induced pluripotent stem cells augments when grown on Graphene oxide-modified nanofibers

Due to the several limitations that surgeons are faced during bone tissue implantation there are daily increases in introducing new cell-co-polymer composites for use in bone tissue engineering approaches. In this study tried to develop a suitable nanostructured bio-composite for enhancing osteogenic differentiation of the human induced pluripotent stem cells (iPSCs). Polyvinylidene fluoride-Graphene oxide (PVDF-GO) nanofibers was fabricated by electrospinning and then characterized using scanning electron microscope, tensile and viability assays. After that osteogenic differentiation of the iPSCs was investigated in three groups, including PVDF, PVDF-GO and tissue culture plate as a control group. Alkaline phosphatase activity and calcium content of the iPSCs cultured on PVDF-GO were significantly higher than those cultured on other groups. In addition, Runx2, osteocalcin and osteonectin genes were up regulated in iPSCs cultured on PVDF-GO significantly higher than those cells cultured on PVDF and control. Finally, osteocalcin and osteopontin proteins expression evaluated and the results confirmed higher osteoinductivity of the PVDF-GO nanofibers in comparison with the PVDF nanofibers. According to the results, it was demonstrated that PVDF-GO nanofibers have a great osteoinductive potential and taking together iPSCs-PVDF-GO nanofibrous construct can be an appropriate bio-implant to use for bone tissue engineering applications.

Polyethylenimine: A new differentiation factor to endothelial/cardiac tissue

Among different tissues, endothelial/cardiac types require specific factors to promote myocardial regeneration after occurred injuries. Herein, cardiac stem cells (CSCs) as the major cell population that involved in cardiovascular repair were selected to study the role of polyethyleneimine (PEI) agent on endothelial differentiation. After preparation of electrospun network of PEI with polyacrylonitrile, the related characterizations were carried out including scanning electron microscope (SEM), field-emission SEM, water contact angle, Fourier transform infrared spectroscopy and mechanical properties. Also, the release kinetic of the corresponding agent was studied up to 7 days. The cell differentiation studies were done in the following with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, Real-time polymerase chain reaction and immunostaining method. The whole obtained results approved the higher differentiation of CSCs into endothelial/cardiac cells. Finally, it is recommended that the PEI delivering increases the healing potency of CSCs and accordingly the regeneration speed of damaged cardiovascular tissue would be improved.

Gradient platform for combinatorial screening of thermoset polymers for biomedical applications

The goal of this work was to design a device for rapid screening of crosslinked thermoset polymers. This gradient curing platform is capable of yielding a library of polyesters with systematically varying mechanical and physicochemical properties and the resultant cellular response. A library of poly(xylitolsebacate) polyesters was prepared in this device by differential curing to yield a gradient polymer. The resultant polymer exhibits a gradient in the storage modulus (1 to 5 MPa), wettability (70° < water contact angle < 110°), degree of crosslinking, degradation rate (3-25% in 7 days), drug release and biological response (ability to support stem cell proliferation and differentiation) from one end of the polymer to the other. Primary human mesenchymal stem cells were cultured to assess the cellular response in vitro. Maximal stem cell proliferation and osteogenesis was observed on the highly crosslinked polyester segments that provide high stiffness, are hydrophobic and are slow degrading as compared to the lower cured counterparts. Under in vivo conditions, this material showed differential response across the gradient without displaying significant concerns for inflammation or infection. This gradient curing device is capable of ascertaining suitable curing conditions to obtain appropriate polymers for application specific requirements. This gradient platform was further used to identify optimal processing parameters to prepare three-dimensional tissue scaffolds such as electrospun fiber mats and porous foams. Thus, this versatile combinatorial platform is well suited for rapid screening of thermoset polymers for biomedical applications.

Poly(ester amide) derived from municipal polyethylene terephthalate waste guided stem cells for osteogenesis

A novel poly(ester amide) was synthesized by using recycled poly(ethylene terephthalate) waste and soybean oil and other renewable resources for bone tissue engineering applications.