Electrospun polyurethane/poly (ɛ-caprolactone) nanofibers promoted the attachment and growth of human endothelial cells in static and dynamic culture conditions.

In this study, the angiogenic capacity of human endothelial cells was studied after being plated on the surface of polyurethane-poly caprolactone (PU/PCL) scaffolds for 72 h. In this study, cells were designated into five different groups, including PU, PU/PCL (2:1), PU/PCL (1:1); PU/PCL (1:2); and PCL. Data revealed that the PU/PCL (2:1) composition had a higher modulus and breakpoint in comparison with the other groups (p < 0.05). Compared to the other groups, the PU/PCL scaffold with a molar ratio of 2:1 had lower the contact angle θ and higher tensile stress (p < 0.05). The mean size of the PU nanofibers was reduced after the addition of PCL (p < 0.05). Based on our data, the culture of endothelial cells on the surface of PU/PCL (2:1) did not cause nitrosative stress and cytotoxic effects under static conditions compared to cells plated on a conventional plastic surface (p > 0.05). Based on data from the static condition, we fabricated a tubular PU/PCL (2:1) construct for six-day dynamic cell culture inside loop air-lift bioreactors. Scanning electron microscopy showed the attachment of endothelial cells to the luminal surface of the PU/PCL scaffold. Cells were flattened and aligned under the culture medium flow. Immunofluorescence imaging showed the attachment of cells to the luminal surface indicated by blue nuclei on the luminal surface. These data demonstrated that the application of PU/PCL substrate could stimulate endothelial cells activity under static and dynamic conditions.

An improved method in fabrication of smart dual-responsive nanogels for controlled release of doxorubicin and curcumin in HT-29 colon cancer cells.

The combination therapy which has been proposed as the strategy for the cancer treatment could achieve a synergistic effect for cancer therapies and reduce the dosage of the applied drugs. On account of the the unique properties as the high absorbed water content, biocompatibility, and flexibility, the targeting nanogels have been considred as a suitable platform. Herein, a non-toxic pH/thermo-responsive hydrogel P(NIPAAm-co-DMAEMA) was synthesized and characterized through the free-radical polymerization and expanded upon an easy process for the preparation of the smart responsive nanogels; that is, the nanogels were used for the efficient and controlled delivery of the anti-cancer drug doxorubicin (DOX) and chemosensitizer curcumin (CUR) simultaneously like a promising strategy for the cancer treatment. The size of the nanogels, which were made, was about 70 nm which is relatively optimal for the enhanced permeability and retention (EPR) effects. The DOX and CUR co-loaded nanocarriers were prepared by the high encapsulation efficiency (EE). It is important to mention that the controlled drug release behavior of the nanocarriers was also investigated. An enhanced ability of DOX and CUR-loaded nanoformulation to induce the cell apoptosis in the HT-29 colon cancer cells which represented the greater antitumor efficacy than the single-drug formulations or free drugs was resulted through the In vitro cytotoxicity. Overall, according to the data, the simultaneous delivery of the dual drugs through the fabricated nanogels could synergistically potentiate the antitumor effects on the colon cancer (CC).

pH- and thermo-sensitive MTX-loaded magnetic nanocomposites: synthesis, characterization, and in vitro studies on A549 lung cancer cell and MR imaging.

In the current study, we proposed a facile method for fabrication of multifunctional pH- and thermo-sensitive magnetic nanocomposites (MNCs) as a theranostic agent for using in targeted drug delivery and magnetic resonance imaging (MRI). To this end, we decorated Fe3O4 magnetic nanoparticles (MNPs) with N,N-dimethylaminoethyl methacrylate (DMAEMA) and N-isopropylacrylamide (NIPAAm), best known for their pH- and thermo-sensitive properties, respectively. We also conjugated mesoporous silica nanoparticles (MSNs) to polymer matrix acting as drug container to enhance the drug encapsulation efficacy. Methotroxate (MTX) as a model drug was successfully loaded in MNCs (M-MNCs) via surface adsorption onto MSNs and electrostatic interaction between drug and carrier. The pH- and temperature-triggered release of MTX was concluded through the evaluation of in vitro release at both physiological and simulated tumor tissue conditions. Based on in vitro cytotoxicity assay results, M-MNCs significantly revealed higher antitumor activity compared to free MTX. In vitro MR susceptibility experiment showed that M-MNCs relatively possessed high transverse relaxivity (r2) of about 0.15 mM-1·ms-1 and a linear relationship between the transverse relaxation rate (R2) and the Fe concentration in the M-MNCs was also demonstrated. Therefore, the designed MNCs can potentially become smart drug carrier, while they also can be promising MRI negative contrast agent.

Co-delivery of hydrophilic and hydrophobic drugs by micelles: a new approach using drug conjugated PEG-PCLNanoparticles.

Co-delivery strategy has been proposed to minimize the amount of each drug and to achieve the synergistic effect for cancer therapies. A conjugate of the antitumor drug, doxorubicin, with diblock methoxy poly (ethylene glycol)-poly caprolactone (mPEG-PCL) copolymer was synthesized by the reaction of mPEG-PCL copolymer with doxorubicin in the presence of p-nitrophenylchloroformate. The conjugated copolymer was characterized in vitro by 1H-NMR, FTIR, DSC and GPC techniques. Then, the doxorubicin conjugated mPEG-PCL(DOX-mPEG-PCL) was self-assembled into micelles in the presence of curcumin in aqueous solution. The resulting micelles were characterized further by various techniques such as dynamic light scattering (DLS) and atomic force microscopy (AFM).The encapsulation efficiency of doxorubicin and curcumin were 82.31 ± 3.32 and 78.15 ± 3.14%, respectively. The results revealed that the micelles formed by the DOX-mPEG-PCL with and without curcumin have spherical structure with average size of 116 and 134 nm respectively. The release behavior of curcumin and doxorubicin loaded to micelles were investigated in a different media. The release rate of micelles consisted of the conjugated copolymer was pH dependent as it was higher at lower pH than in neutral condition. Another feature of the conjugated micelles was a sustained release profile. The cytotoxicity of micelles were evaluated by MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide, atetrazole) assay on lung cancer A549 cell lines. In vitro cytotoxicity assay showed that the mPEG-PCL copolymer did not affect the growth of A549 cells. The cytotoxic activity of the micelles against A549 cells was greater than free doxorubicin and free curcumin.

Fluorescent multi-responsive cross-linked P(N-isopropylacrylamide)-based nanocomposites for cisplatin delivery.

Magnetic, pH and temperature-sensitive, poly(N-isopropylacrylamide) (PNIPAM)-based nanocomposites with fluorescent properties were synthesized by free radical copolymerization-cross linking of NIPAM, N,N-dimethylaminoethyl methacrylate (DMAEMA) and 4-acrylamidofluorescein (AFA). The model anti-cancer drug, cisplatin (CDDP), was loaded into the resulted nanogel. For the production of CDDP-loaded nanocomposite, Fe3O4 magnetic nanoparticles (MNPs) and CDDP were loaded into the nanogel. Field-emission scanning electron microscopy (FE-SEM) indicated that the size of nanogel and CDDP-loaded nanocomposite were about 90 and 160 nm, respectively. The encapsulation efficiency of CCDP was found up to 65%. The loaded CCDP showed sustained thermal and pH-responsive drug release. A high level of drug release was observed under the conditions of low pH and high temperature. The lower critical solution temperature (LCST) of synthesized nanogel was about 40 °C. CDDP-loaded nanocomposite showed a volume phase transition from 282 to 128 nm at its LCST. Accordingly, in this study, the synthesized nanocomposite can be employed as a stimuli-responsive anti-cancer drug delivery system and the pH and temperature of solution have the potential to monitor the drug release.

Preparation of pH sensitive insulin-loaded nano hydrogels and evaluation of insulin releasing in different pH conditions.

In the recent years, temperature and pH-sensitive hydrogels were developed as suitable carriers for drug delivery. In this study, four different pH-sensitive nanohydrogels were designed for an oral insulin delivery modeling. NIPAAm-MAA-HEM copolymers were synthesized by radical chain reaction with 80:8:12 ratios respectively. Reactions were carried out in four conditions including 1,4-dioxan and water as two distinct solution under nitrogen gas-flow. The copolymers were characterized with FT-IR, SEM and TEM. Copolymers were loaded with regular insulin by modified double emulsion method with ratio of 1:10. Release study carried out in pH 1.2 and pH 6.8 at 37 °C. For pH 6.8 and pH 1.2, 2 mg of the insulin loaded nanohydrogels was float in a beaker containing 100 mL of PBS with pH 6.8 and 100 mL of HCl solution with pH 1.2, respectively. Sample collection was done in different times and HPLC was used for analysis of samples using water/acetonitrile (65/35) as the mobile phase. Nanohydrogels synthesis reaction yield was 95 %, HPLC results showed that loading in 1,4-dioxan without cross-linker nanohydrogels was more than others, also indicated that the insulin release of 1,4-dioxan without cross-linker nanohydrogels at acidic pH is less, but in pH 6.8 is the most. Results showed that by opting suitable polymerization method and selecting the best nanohydrogels, we could obtain a suitable insulin loaded nanohydrogels for oral administration.

Folate receptor-mediated delivery system based on chitosan coated polymeric nanoparticles for combination therapy of breast cancer.

Combination therapy using two or more drugs with different mechanisms of action is an effective strategy for treating cancer. This is because of the synergistic effect of complementary drugs that enhances their effectiveness. However, this approach has some limitations, such as non-specific distribution of the drugs in the tumor and the occurrence of dose-dependent toxicity to healthy tissues. To overcome these issues, we have developed a folate receptor-mediated co-delivery system that improves the access of chemotherapy drugs to the tumor site. We prepared a nanoplatform by encapsulating paclitaxel (PTX) and curcumin (CUR) in poly(caprolactone)-poly(ethylene glycol)-poly(caprolactone) (PCL-PEG-PCL) co-polymer using a double emulsion method and coating nanoparticles with pH-responsive chitosan-folic acid (CS-FA) conjugate. The nanocarrier's physicochemical properties were studied, confirming successful preparation with appropriate size and morphology. PTX and CUR could be released synchronously in a controlled and acid-facilitated manner. The dual drug-loaded nanocarrier exhibited excellent anti-tumor efficiency in MDA-MB-231 cells in vitro. The active targeting effect of FA concluded from the high inhibitory effect of dual drug-loaded nanocarrier on MDA-MB-231 cells, which have overexpressed folate receptors on their surface, compared to Human umbilical vein endothelial cells (HUVEC). Overall, the nanoengineered folate receptor-mediated co-delivery system provides great potential for safe and effective cancer therapy.

Effects of chitosan and TiO2 nanoparticles on the antibacterial property and ability to self-healing of cracks and retrieve mechanical characteristics of dental composites.

The aim of this study was to improve the self-healing properties of dental nanocomposite using nanoparticles of TiO2 and chitosan. We evaluated flexural and compressive strength, crack-healing, and self-healing lifespan after 3 months of water aging. The effect of the developed composite on cell viability and toxicity was assessed by an MTT assay on human alveolar basal epithelial cells (A549 cell line). The nanocomposite included 7.5 wt% polyurea-formaldehyde (PUF) and 0, 0.5, and 1 wt% n-TiO2 and chitosan. After the fracture, the samples were put in a mold for 1-90 days to enable healing. Then, the fracture toughness of the healed nanocomposites and the healing yield were measured. The flexural strength of the nanocomposite improved by adding 0.5 wt% n-TiO2, while the compressive strength increased after adding 0.5 wt% chitosan (p > 0.1). When these two materials were used simultaneously, the flexural strength was improved by around 2%; however, the compressive strength was unaffected. Compared to the other sample, the nanocomposite with 0.5 wt% n-TiO2 and chitosan had higher KIC-healing and self-healing efficiency. Self-healing efficacy had no significant effect of water aging over 90 days compared to one day (p > 0.1), demonstrating that the PUF nanocapsules were not damaged.

Thermosensitive and biodegradable PCL-based hydrogels: potential scaffolds for cartilage tissue engineering.

Due to a lack of sufficient blood supply and unique physicochemical properties, the treatment of injured cartilage is laborious and needs an efficient strategy. Unfortunately, most of the current therapeutic approaches are, but not completely, unable to restore the function of injured cartilage. Tissue engineering-based modalities are an alternative option to reconstruct the injured tissue. Considering the unique structure and consistency of cartilage tissue (osteochondral junction), it is mandatory to apply distinct biomaterials with unique properties slightly different from scaffolds used for soft tissues. PCL is extensively used for the fabrication of fine therapeutic scaffolds to accelerate the restorative process. Thermosensitive PCL hydrogels with distinct chemical compositions have paved the way for sophisticated cartilage regeneration. This review aimed to collect recent findings regarding the application of PCL in hydrogels blended with natural, synthetic materials in the context of cartilage healing.

Natural and synthetic nanovectors for cancer therapy.

Nanomaterials have been extensively studied in cancer therapy as vectors that may improve drug delivery. Such vectors not only bring numerous advantages such as stability, biocompatibility, and cellular uptake but have also been shown to overcome some cancer-related resistances. Nanocarrier can deliver the drug more precisely to the specific organ while improving its pharmacokinetics, thereby avoiding secondary adverse effects on the not target tissue. Between these nanovectors, diverse material types can be discerned, such as liposomes, dendrimers, carbon nanostructures, nanoparticles, nanowires, etc., each of which offers different opportunities for cancer therapy. In this review, a broad spectrum of nanovectors is analyzed for application in multimodal cancer therapy and diagnostics in terms of mode of action and pharmacokinetics. Advantages and inconveniences of promising nanovectors, including gold nanostructures, SPIONs, semiconducting quantum dots, various nanostructures, phospholipid-based liposomes, dendrimers, polymeric micelles, extracellular and exome vesicles are summarized. The article is concluded with a future outlook on this promising field.

Synthesis, characterization and in vitro studies of doxorubicin-loaded magnetic nanoparticles grafted to smart copolymers on A549 lung cancer cell line.

BACKGROUND: The aim of present study was to develop the novel methods for chemical and physical modification of superparamagnetic iron oxide nanoparticles (SPIONs) with polymers via covalent bonding entrapment. These modified SPIONs were used for encapsulation of anticancer drug doxorubicin. METHOD: At first approach silane-grafted magnetic nanoparticles was prepared and used as a template for polymerization of the N-isopropylacrylamide (NIPAAm) and methacrylic acid (MAA) via radical polymerization. This temperature/pH-sensitive copolymer was used for preparation of DOX-loaded magnetic nanocomposites. At second approach Vinyltriethoxysilane-grafted magnetic nanoparticles were used as a template to polymerize PNIPAAm-MAA in 1, 4 dioxan and methylene-bis-acrylamide (BIS) was used as a cross-linking agent. Chemical composition and magnetic properties of Dox-loaded magnetic hydrogel nanocomposites were analyzed by FT-IR, XRD, and VSM. RESULTS: The results demonstrate the feasibility of drug encapsulation of the magnetic nanoparticles with NIPAAm-MAA copolymer via covalent bonding. The key factors for the successful prepardtion of magnetic nanocomposites were the structure of copolymer (linear or cross-linked), concentration of copolymer and concentration of drug. The influence of pH and temperature on the release profile of doxorubicin was examined. The in vitro cytotoxicity test (MTT assay) of both magnetic DOx-loaded nanoparticles was examined. The in vitro tests showed that these systems are no toxicity and are biocompatible. CONCLUSION: IC50 of DOx-loaded Fe3O4 nanoparticles on A549 lung cancer cell line showed that systems could be useful in treatment of lung cancer.

Synthesis and Characterization of a Novel Dual-Responsive Nanogel for Anticancer Drug Delivery.

In this study, to reduce the side effects of anticancer drugs and also to increase the efficiency of current drug delivery systems, a pH and temperature-responsive polymeric nanogel was synthesized by copolymerization of N-vinylcaprolactam (VCL) and acrylic acid (AA) monomers (P(VCL-co-AA)) with a novel cross-linker, triethylene glycol dimethacrylate (TEGDMA), as a biocompatible and nontoxic component. The structural and physicochemical features of the P(VCL-co-AA) nanogel were characterized by FT-IR, DLS/Zeta potential, FE-SEM, and 1HNMR techniques. The results indicated that spherical polymeric nanogel was successfully synthesized with a 182 nm diameter. The results showed that the polymerization process continues with the opening of the carbon-carbon double bond of monomers, which was approved by C-C band removing located at 1600 cm-1. Doxorubicin (Dox) as a chemotherapeutic agent was loaded into the P(VCL-co-AA), whit a significant loading of Dox (83%), and the drug release profile was investigated in the physiological and cancerous site simulated conditions. P(VCL-co-AA) exhibited a pH and temperature-responsive behavior, with an enhanced release rate in the cancerous site condition. The biocompatibility and nontoxicity of P(VCL-co-AA) were approved by MTT assay on the normal human foreskin fibroblasts-2 (HFF-2) cell line. Also, Dox-loaded P(VCL-co-AA) had excellent toxic behavior on the Michigan Cancer Foundation-7 (MCF-7) cell line as model cancerous cells. Moreover, Dox-loaded P(VCL-co-AA) had higher toxicity in comparison with free Dox, which would be a vast advantage in reducing Dox side effects in the clinical cancer treatment applications.

Enhancing the function of PLGA-collagen scaffold by incorporating TGF-ß1-loaded PLGA-PEG-PLGA nanoparticles for cartilage tissue engineering using human dental pulp stem cells.

Since cartilage has a limited capacity for self-regeneration, treating cartilage degenerative disorders is a long-standing difficulty in orthopedic medicine. Researchers have scrutinized cartilage tissue regeneration to handle the deficiency of cartilage restoration capacity. This investigation proposed to compose an innovative nanocomposite biomaterial that enhances growth factor delivery to the injured cartilage site. Here, we describe the design and development of the biocompatible poly(lactide-co-glycolide) acid-collagen/poly(lactide-co-glycolide)-poly(ethylene glycol)-poly(lactide-co-glycolide) (PLGA-collagen/PLGA-PEG-PLGA) nanocomposite hydrogel containing transforming growth factor-ß1 (TGF-ß1). PLGA-PEG-PLGA nanoparticles were employed as a delivery system embedding TGF-ß1 as an articular cartilage repair therapeutic agent. This study evaluates various physicochemical aspects of fabricated scaffolds by 1HNMR, FT-IR, SEM, BET, and DLS methods. The physicochemical features of the developed scaffolds, including porosity, density, degradation, swelling ratio, mechanical properties, morphologies, BET, ELISA, and cytotoxicity were assessed. The cell viability was investigated with the MTT test. Chondrogenic differentiation was assessed via Alcian blue staining and RT-PCR. In real-time PCR testing, the expression of Sox-9, collagen type II, and aggrecan genes was monitored. According to the results, human dental pulp stem cells (hDPSCs) exhibited high adhesion, proliferation, and differentiation on PLGA-collagen/PLGA-PEG-PLGA-TGFß1 nanocomposite scaffolds compared to the control groups. SEM images displayed suitable cell adhesion and distribution of hDPSCs throughout the scaffolds. RT-PCR assay data displayed that TGF-ß1 loaded PLGA-PEG-PLGA nanoparticles puts forward chondroblast differentiation in hDPSCs through the expression of chondrogenic genes. The findings revealed that PLGA-collagen/PLGA-PEG-PLGA-TGF-ß1 nanocomposite hydrogel can be utilized as a supportive platform to support hDPSCs differentiation by implementing specific physio-chemical features.

Novel nanocomposite scaffold based on gelatin/PLGA-PEG-PLGA hydrogels embedded with TGF-ß1 for chondrogenic differentiation of human dental pulp stem cells in vitro.

In the current study, a novel nanocomposite hydrogel scaffold comprising of natural-based gelatin and synthetic-based (poly D, L (lactide-co-glycolide) -b- poly (ethylene glycol)-b- poly D, L (lactide-co-glycolide) (PLGA-PEG-PLGA) triblock copolymer was developed and loaded with transforming growth factor- ß1 (TGF-ß1). Synthesized scaffolds' chemical structure was examined by 1H NMR and ATR-FTIR. Scanning electron microscopy (SEM) confirmed particle size and morphology of the prepared nanoparticles as well as the scaffolds. The morphology analysis revealed a porous interconnected structure throughout the scaffold with a pore size dimension of about 202.05 µm. The swelling behavior, in vitro degradation, mechanical properties, density, and porosity were also evaluated. Phalloidin/DAPI staining was utilized for confirming the extended cytoskeleton of the chondrocytes. Alcian blue staining was conducted to determine cartilaginous matrix sulfated glycosaminoglycan (sGAG) synthesis. Eventually, over a period of 21 days, a real-time RT-PCR analysis was applied to measure the mRNA expression of chondrogenic marker genes, type-II collagen, SOX 9, and aggrecan, in hDPSCs cultured for up to 21 days to study the influence of gelatin/PLGA-PEG-PLGA-TGF-ß1 hydrogels on hDPSCs. The findings of the cell-encapsulating hydrogels analysis suggested that the adhesion, viability, and chondrogenic differentiation of hDPSCs improved by gelatin/PLGA-PEG-PLGA-TGF-ß1 nanocomposite hydrogels. These data supported the conclusion that gelatin/PLGA-PEG-PLGA-TGF-ß1 nanocomposite hydrogels render the features that allow thein vitrofunctionality of encapsulated hDPSCs and hence can contribute the basis for new effective strategies for the treatment of cartilage injuries.

Synthesis and characterization of growth factor free nanoengineered bioactive scaffolds for bone tissue engineering.

BACKGROUND: To address the obstacles that come with orthopedic surgery for biological graft tissues, including immune rejections, bacterial infections, and weak osseointegration, bioactive nanocomposites have been used as an alternative for bone grafting since they can mimic the biological and mechanical properties of the native bone. Among them, PCL-PEG-PCL (PCEC) copolymer has gained much attention for bone tissue engineering as a result of its biocompatibility and ability for osteogenesis. METHODS: Here, we designed a growth factor-free nanoengineered scaffold based on the incorporation of Fe3O4 and hydroxyapatite (HA) nanoparticles into the PCL-PEG-PCL/Gelatin (PCEC/Gel) nanocomposite. We characterized different formulations of nanocomposite scaffolds in terms of physicochemical properties. Also, the mechanical property and specific surface area of the prepared scaffolds, as well as their feasibility for human dental pulp stem cells (hDPSCs) adhesion were assessed. RESULTS: The results of in vitro cell culture study revealed that the PCEC/Gel Fe3O4&HA scaffold could promote osteogenesis in comparison with the bare scaffold, which confirmed the positive effect of the Fe3O4 and HA nanoparticles in the osteogenic differentiation of hDPSCs. CONCLUSION: The incorporation of Fe3O4 and HA with PCEC/gelatin could enhance osteogenic differentiation of hDPSCs for possible substitution of bone grafting tissue.

Biofunctional phosphorylated magnetic scaffold for bone tissue engineering.

The development of highly bioactive engineered scaffolds is required to promote bone regeneration and the success of bone tissue engineering treatment approaches. This study attempts to fabricate a biofunctional magnetic scaffold based on new phosphorylated polycaprolactone combined with gelatin (MNPs-PCL-P/gelatin). Phosphorylated polymer and magnetic nanoparticles (MNPs) were synthesized and characterized by NMR, FT-IR, TEM, and DLS instruments. The synthetic polymer, MNPs, and biopolymer were mixed then freeze-dried to prepare a porous scaffold. Physiochemical assessments showed that a scaffold with well-developed porous morphology, and stable structure was obtained. MNPs-PCL-P/gelatin scaffold had no toxicity on human dental pulp stem cells (hDPSCs). The use of phosphorous-containing polymer resulted in improvement of the scaffold's osteoconductivity to support proper cell attachment and promote cell proliferation. Phosphate group by mimicking function of bone phosphate groups stimulate bone mineralization that reflected by alizarin red S staining assay. The presence of MNPs resulted in higher ALP activity and increased expression level of RUNX2, BMP2 osteogenic biomarkers. Also, phosphorylation enhanced osteoinductivity of scaffold and upregulate RUNX2, BMP2, COL1A1, and OCN genes in phosphors-containing scaffold test groups. It seems that biocompatible MNPs-PCL-P/gelatin scaffold possesses the potential of applications in bone tissue engineering.

The fabrication of halloysite nanotube-based multicomponent hydrogel scaffolds for bone healing.

Bone tissue engineering, as an alternative for common available therapeutic approaches, has been developed to focus on reconstructing of the missing tissues and restoring their functionality. In this work, three-dimensional (3D) nanocomposite scaffolds of polycaprolactone-polyethylene glycol-polycaprolactone/gelatin (PCEC/Gel) were prepared by freeze-drying method. Biocompatible nanohydroxyapatite (nHA), iron oxide nanoparticle (Fe3O4) and halloysite nanotube (HNT) powders were added to the polymer matrix aiming to combine the osteogenic activity of nHA or Fe3O4 with high mechanical strength of HNT. The scanning electron microscope (SEM) methods was utilized to characterize the nanotube morphology of HNT as well as nanoparticles of Fe3O4 and nHA. Prepared scaffolds were characterized via Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), and SEM methods. In addition, the physical behavior of scaffolds was evaluated to explore the influence of HNT on the physicochemical properties of composites. Cell viability and attachment were investigated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assay and SEM on human dental pulp-derived mesenchymal stem cells (h-DPSCs) in-vitro. Cell proliferation was observed without any cytotoxicity effect on h-DPSCs for all examined scaffolds. Alizarin red (ARS) and alkaline phosphatase (ALP) staining were carried out to determine the osteoconductivity of scaffolds. The data demonstrated that all PCEC/Gel/HNT hydrogel scaffolds supported osteoblast differentiation of hDPSCs with moderate effects on cell proliferation. Moreover, PCEC/Gel/HNT/nHA with proper mechanical strength showed better biological activity compared to PCEC/Gel/HNT/Fe3O4 and PCEC/Gel/HNT scaffolds. Therefore, this study suggested that with proper fillers content, PCEC/Gel/HNT nanocomposite hydrogels alone or in a complex with nHA, Fe3O4 could be a suitable candidate for hard tissue regeneration.

Gentamycin-loaded halloysite-based hydrogel nanocomposites for bone tissue regeneration: fabrication, evaluation of the antibacterial activity and cell response.

Biocompatible hydrogels are promising approaches for bone repair and engineering. A novel therapeutic nanocomposite hydrogel was designed based on triblock copolymer poly e-caprolactone (PCL)-polyethylene glycol-PCL and natural gelatin (PCEC/GEL) and reinforced with halloysite nanotube (HNT). Gentamicin (GM) loaded HNT was immobilized in polymeric hydrogel matrix to fabricate scaffolds using the freeze-drying method. Scaffolds were characterized via Fourier transform infrared (FT-IR), x-ray powder diffraction, and scanning electron microscope (SEM) methods. The swelling ratio, density, porosity, degradation, and mechanical behavior were evaluated to investigate the effects of HNT on the physicochemical properties of the composite. Cell viability and cell attachment were investigated by microculture tetrazolium (MTT) assay and SEM. Cell proliferation was observed without any cytotoxicity effect on human dental pulp-derived mesenchymal stem cells (h-DPSCs). Alizarin red staining and real-time reverse transcription polymerase chain reaction (QRT-PCR) assay were carried out to monitor the osteoconductivity of scaffolds on h-DPSCs which were seeded drop wise onto the top of scaffolds. The quantification of the messenger RNA (mRNA) expression of osteogenic marker genes, bone morphogenetic protein 2, SPARK, bone gamma-carboxyglutamate protein and runt-related transcription factor 2 over a period of 21 d of cell seeding, demonstrated that cell-encapsulating PCEC/GEL/HNT-GM hydrogel scaffolds supported osteoblast differentiation of h-DPSCs into osteogenic cells through the up-regulation of related genes along with moderate effects on cell viability. Moreover, the antibiotics loading reduced bacterial growth while maintaining the osteogenic properties of the scaffold. Therefore, the bactericidal PCEC/GEL/HNT-GM hydrogel nanocomposite, with enhanced durability, maintenance the functionality of seeded cellsin vitrothat can be a remarkable dual-functional candidate for hard tissue reconstruction and customized bone implants fabrication via the direct incorporation of bactericidal drug to prevent infection.

Osteogenic potential of the growth factors and bioactive molecules in bone regeneration.

The growing need for treatment of the impaired bone tissue has resulted in the quest for the improvement of bone tissue regeneration strategies. Bone tissue engineering is trying to create bio-inspired systems with a coordinated combination of the cells, scaffolds, and bioactive factors to repair the damaged bone tissue. The scaffold provides a supportive matrix for cell growth, migration, and differentiation and also, acts as a delivery system for bioactive factors. Bioactive factors including a large group of cytokines, growth factors (GFs), peptides, and hormonal signals that regulate cellular behaviors. These factors stimulate osteogenic differentiation and proliferation of cells by activating the signaling cascades related to ossification and angiogenesis. GFs and bioactive peptides are significant parts of the bone tissue engineering systems. Besides, the use of the osteogenic potential of hormonal signals has been an attractive topic, particularly in osteoporosis-related bone defects. Due to the unstable nature of protein factors and non-specific effects of hormones, the engineering of scaffolds to the controlled delivery of these bioactive molecules has paramount importance. This review updates the growth factors, engineered peptides, and hormones that are used in bone tissue engineering systems. Also, discusses how these bioactive molecules may be linked to accelerating bone regeneration.

Osteogenic effects of the bioactive small molecules and minerals in the scaffold-based bone tissue engineering.

Reconstruction of the damaged bone is a striking challenge in the medical field. The bone grafts as a current treatment is associated with inherent limitations; hence, the bone tissue engineering as an alternative therapeutic approach has been considered in the recent decades. Bone tissue engineering aims at replacing the lost tissue and restoring its function by recapitulating the natural regeneration process. Concerted participation and combination of the biocompatible materials, osteoprogenitor/ stem cells and bioactive factors closely mimic the bone microenvironment. The bioactive factors regulate the cell behavior and they induce the stem cells to osteogenic differentiation by activating specific signaling cascades. Growth factors (GFs) are the most important bioactive molecules and mediators of the natural bone repair process. Although these soluble factors have approved applications in the bone regeneration, however, there are several limitations such as the instability, high dose requirements, and serious side effects which could restrict their clinical usage. Alternatively, a new generation of bioactive molecules with the osteogenic properties are used. The non-peptide organic or inorganic molecules are physiologically stable and non-immunogenic due to their small size. Many of them are obtained from the natural resources and some are synthesized through the chemical methods. As a result, these molecules have been introduced as the cost-effective osteogenic agents in the bone tissue regeneration. In this paper, three groups of these bioactive agents including the organic small molecules, minerals and metallic nanoparticles have been investigated, considering their function in accelerating the bone regeneration. We review the recent in vitro and in vivo studies that utilized the osteogenic molecules to promote the bone formation in the scaffold-based bone tissue engineering systems.