Amino acid surface modified bioglass: A candidate biomaterial for bone tissue engineering1.

Bioglasses are solid materials consisted of sodium oxide, calcium oxide, silicon dioxide and phosphorus in various proportions and have used in bone tissue engineering. There have been ongoing efforts to improve the surface properties of bioglasses to increase biocompatibility and performance. The aim of the present study is to modify the bioglass surface with an amino acid mixture consisting of arginine, aspartic acid, phenylalanine, cysteine, histidine and lysine, to characterize the surface, and to evaluate the performance and biocompatibility in vitro and in vivo. The untreated bioglass, bioglass kept in simulated body fluid (SBF), and modified bioglass were used in further evaluation. After confirmation of the surface modification with FT-IR analyses and SEM analyses, MC3T3-E1 preosteoblasts adhesion on the surface was also revealed by SEM. The modified bioglass had significantly higher ALP activity in colorimetric measurement, rate of calcium accumulations in Alizarin red s staining, lower rate of cell death in Annexin-V/PI staining to determine apoptosis and necrosis. Having higher cell viability rate in MTT test and absence of genotoxicity in micronucleus test (OECD 487), the modified bioglass was further confirmed for biocompatibility in vitro. The results of the rat tibial defect model revealed that the all bioglass treatments had a significantly better bone healing score compared to the untreated negative control. However, the modified bioglass exhibited significantly better bone healing efforts especially during the first and the second months compared to the other bioglass treatment treatments. As a result, the amino acid surface modification of bioglasses improves the surface biocompatibility and osteogenic performance that makes the amino acid modified bioglass a better candidate for bone tissue engineering. RESEARCH HIGHLIGHTS: Bioglass surface modification with amino acids contributes to bioglass-tissue interaction with an improved cell attachment. Modified bioglass increases in vitro Alp activity and calcium accumulation, and also positively affects cell behavior by supporting cell adaptation. Bioglass exerts osteogenic potential in vivo especially during early bone healing.

The comparison of contribution of GO and rGO produced by green synthesis to the properties of CMC-based wound dressing material.

Herein, GO (graphene oxide) or rGO (reduced graphene oxide) which is produced by the green synthesis method using plant extract (Laurus nobilis) was incorporated into a polymeric structure consisting of carboxymethyl cellulose (CMC) and polyethylene glycol (PEG) to produce a wound dressing material with enhanced mechanical and electrical properties. The effect of GO and rGO on the wound dressing features of the produced materials was investigated and compared to each other. Conductivity tests demonstrated that rGO contributed more significantly to the electrical conductivity than GO. While rGO-CMC/PEG/CA reached 3.01 × 10-6 S.cm-1 as the conductivity value, that of GO-CMC/PEG/CA was determined as 0.85 × 10-6 S.cm-1. As for the mechanical tests, it was seen that rGO achieved the best results in terms of elastic modulus (588.62 N/mm2), tensile strength (94.95 MPa) and elongation at break (17.64 %) compared to GO reinforced and pure hydrogel. Curcumin and ascorbic acid were used for antibiotic-free wound treatment and their release kinetics were also modeled. The results showed that rGO reinforced hydrogel provided a more controlled release. All results assured that both the produced GO reinforced and especially rGO reinforced hydrogels could be utilized as modern wound dressing materials with suitable properties to achieve remarkable results for wound healing.

Production of Reduced Graphene Oxide by Using Three Different Microorganisms and Investigation of Their Cell Interactions.

Despite the huge and efficient functionalities of reduced graphene oxide (RGO) for bioengineering applications, the use of harsh chemicals and unfavorable techniques in their production remains a major challenge. Microbial production of reduced graphene oxide (RGO) using specific bacterial strains has gained interest as a sustainable and efficient method. The reduction of GO to RGO by selected bacterial strains was achieved through their enzymatic activities and resulted in the removal of oxygen functional groups from GO, leading to the formation of RGO with enhanced structural integrity. The use of microorganisms offers a sustainable approach, utilizing renewable carbon sources and mild reaction conditions. This study investigates the production of RGO using three different bacterial strains: Lactococcus lactis (L. Lactis), Lactobacillus plantarum (L. plantarum), and Escherichia coli (E. coli) and evaluates its toxicity for safe utilization. The aim is to assess the quality of the produced RGO and evaluate its toxicity for potential applications. Thus, this study focused on the microbial production of reduced graphene oxides well as the investigation of their cellular interactions. Graphite-derived graphene oxide was used as a starting material and microbially reduced GO products were characterized using the FTIR, Raman, XRD, TGA, and XPS methods to determine their physical and chemical properties. FTIR shows that the epoxy and some of the alkoxy and carboxyl functional groups were reduced by E. coli and L. lactis, whereas the alkoxy groups were mostly reduced by L. plantarum. The ID/IG ratio from Raman spectra was found as 2.41 for GO. A substantial decrease in the ratio as well as defects was observed as 1.26, 1.35, and 1.46 for ERGO, LLRGO, and LPRGO after microbial reduction. The XRD analysis also showed a significant reduction in the interlayer spacing of the GO from 0.89 to 0.34 nm for all the reduced graphene oxides. TGA results showed that reduction of GO with L. lactis provided more reduction than other bacteria and formed a structure closer to graphene. Similarly, analysis with XPS showed that L lactis provides the most effective reduction with a C/O ratio of 3.70. In the XPS results obtained with all bacteria, it was observed that the C/O ratio increased because of the microbial reduction. Toxicity evaluations were performed to assess the biocompatibility and safety of the produced RGO. Cell viability assays were conducted using DLD-1 and CHO cell lines to determine the potential cytotoxic effects of RGO produced by each bacterial strain. Additionally, apoptotic, and necrotic responses were examined to understand the cellular mechanisms affected by RGO exposure. The results indicated that all the RGOs have concentration-dependent cytotoxicity. A significant amount of cell viability of DLD-1 cells was observed for L. lactis reduced graphene oxide. However, the highest cell viability of CHO cells was observed for L. plantarum reduced graphene oxide. All reduced graphene oxides have low apoptotic and necrotic responses in both cell lines. These findings highlight the importance of considering the specific bacterial strain used in RGO production as it can influence the toxicity and cellular response of the resulting RGO. The toxicity and cellular response to the final RGO can be affected by the particular bacterial strain that is employed to produce it. This information will help to ensure that RGO is used safely in a variety of applications, including tissue engineering, drug delivery systems, and biosensors, where comprehension of its toxicity profile is essential.

Delivery of siRNA using hyaluronic acid-guided nanoparticles for downregulation of CXCR4.

In this study, effective transport of small interfering RNAs (siRNAs) via hyaluronic acid (HA) receptor was carried out with biodegradable HA and low-molecular weight polyethyleneimine (PEI)-based transport systems. Gold nanoparticles (AuNPs) capable of giving photothermal response, and their conjugates with PEI and HA, were also added to the structure. Thus, a combination of gene silencing, photothermal therapy and chemotherapy, has been accomplished. The synthesized transport systems ranged in size, between 25 and 690 nm. When the particles were applied at a concentration of 100 µg mL-1 (except AuPEI NPs) in vitro, cell viability was above 50%. Applying radiation after the conjugate/siRNA complex (especially those containing AuNP) treatment, increased the cytotoxic effect (decrease in cell viability of 37%, 54%, 13%, and 15% for AuNP, AuPEI NP, AuPEI-HA, and AuPEI-HA-DOX, respectively) on the MDA-MB-231 cell line. CXCR4 gene silencing via the synthesized complexes, especially AuPEI-HA-DOX/siRNA was more efficient in MDA-MB-231 cells (25-fold decrease in gene expression) than in CAPAN-1 cells. All these results demonstrated that the synthesized PEI-HA and AuPEI-HA-DOX conjugates can be used as siRNA carriers that are particularly effective, especially in the treatment of breast cancer.

In vitro comparison of nanofibrillar and macroporous-spongious composite tissue scaffolds for periodontal tissue engineering.

PURPOSE/AIM OF THE STUDY: The ultimate goal of periodontal treatment is to regenerate the lost periodontal tissues. The interest in nanomaterials in dentistry is growing rapidly and has focused on improvements in various biomedical applications, such as periodontal regeneration and periodontal tissue engineering. To enhance periodontal tissue regeneration, hydroxyapatite (HA) was used in conjunction with other scaffold materials, such as Poly lactic-co-glycolic-acid (PLGA) and collagen (C). The main target of this study was to compare the effects of nano and macrostructures of the tissue scaffolds on cell behavior in vitro for periodontal tissue engineering. MATERIALS AND METHODS: Nanofibrillar and macroporous-spongious composite tissue scaffolds were produced using PLGA/C/HA. Subgroups with BMP-2 signal molecule and without HA were also created. The scaffolds were characterized by FTIR, SEM/EDX techniques, and mechanical tests. The scaffolds were compared in the periodontal ligament (PDL) and MCT3-E1 cell cultures. The cell behaviors; adhesions by SEM, proliferation by WST-1, differentiation by ALP and mineralization with Alizarin Red Tests were determined. RESULTS: Cell adhesion and mineralization were higher in the nanofibrillar scaffolds compared to the macroporous-spongious scaffolds. Macroporous-spongious scaffolds seemed better for the proliferation of PDL cells and differentiation of MC3T3-E1-preosteoblastic cells, while nanofibrillar scaffolds were more convenient for the differentiation of PDL cells and proliferation of MC3T3-E1-preosteoblastic cells. CONCLUSIONS: In general, nanofibrillar scaffolds showed more favorable results in cell behaviors, compared to the macroporous-spongious scaffolds, and mostly, BMP-2 and HA promoted the activities of the cells.

Phosphorus-nitrogen compounds: part 53-synthesis, characterization, cytotoxic and antimicrobial activity, DNA interaction and molecular docking studies of new mono- and dispirocyclotriphosphazenes with pendant arm(s).

Mono-/dispirocyclotriphosphazenes with pendant arm(s) are robust, but they are less investigated inorganic ring systems. In this study, a series of mono (3 and 4)- and dispirocyclotriphosphazenes with 4-chloro-benzyl pendant arm(s) (13-16) was obtained from the Cl exchange reactions of hexachlorocyclotriphosphazene with sodium (N-benzyl)aminopropanoxides (1 and 2). When compound (3) reacted with excess pyrrolidine, morpholine, tetra-1,4-dioxa-8-azaspiro[4,5]decane (DASD) and piperidine, the fully substituted monospirocyclotriphosphazenes (7, 9, 10 and 12) occurred. But, the reactions of 4 with excess piperidine and morpholine produced the gem-piperidino (5)- and morpholino (6)-substituted monospirocyclotriphosphazenes, whereas the reactions of 4 with excess pyrrolidine and DASD gave the fully substituted monospirocyclotriphosphazenes (8) and (11). However, it should be indicated that these derivatives were obtained to be used for the investigation of their spectral, stereogenic and biological properties. The structures of 5, 7 and 14 were determined crystallographically. X-ray data of 5 and 14 displayed that both of compounds were chiral in solid state, and their absolute configurations were assigned as R and RR. Additionally, the antimicrobial activities of phosphazenes were investigated. Minimum inhibitory concentrations, minimal bacterial concentrations and minimum fungicidal concentrations of phosphazenes were determined. The interactions of phosphazenes with plasmid DNA were evaluated by agarose gel electrophoresis. The cytotoxic activities of compounds were studied against L929 fibroblast and DLD-1 colon cancer cells. In addition, density functional theory calculations of 5, 7 and 14 were reported, and their molecular docking studies with DNA, E. coli DNA gyrase and topoisomerase IV were presented.

The Pimpled Gold Nanosphere: A Superior Candidate for Plasmonic Photothermal Therapy.

BACKGROUND: The development of highly efficient nanoparticles to convert light to heat for anti-cancer applications is quite a challenging field of research. METHODS: In this study, we synthesized unique pimpled gold nanospheres (PGNSs) for plasmonic photothermal therapy (PPTT). The light-to-heat conversion capability of PGNSs and PPTT damage at the cellular level were investigated using a tissue phantom model. The ability of PGNSs to induce robust cellular damage was studied during cytotoxicity tests on colorectal adenocarcinoma (DLD-1) and fibroblast cell lines. Further, a numerical model of plasmonic (COMSOL Multiphysics) properties was used with the PPTT experimental assays. RESULTS: A low cytotoxic effect of thiolated polyethylene glycol (SH-PEG400-SH-) was observed which improved the biocompatibility of PGNSs to maintain 89.4% cell viability during cytometry assays (in terms of fibroblast cells for 24 hrs at a concentration of 300 µg/mL). The heat generated from the nanoparticle-mediated phantom models resulted in ΔT=30°C, ΔT=23.1°C and ΔT=21°C for the PGNSs, AuNRs, and AuNPs, respectively (at a 300 µg/mL concentration and for 325 sec). For the in vitro assays of PPTT on cancer cells, the PGNS group induced a 68.78% lethality (apoptosis) on DLD-1 cells. Fluorescence microscopy results showed the destruction of cell membranes and nuclei for the PPTT group. Experiments further revealed a penetration depth of sufficient PPTT damage in a physical tumor model after hematoxylin and eosin (H&E) staining through pathological studies (at depths of 2, 3 and 4 cm). Severe structural damages were observed in the tissue model through an 808-nm laser exposed to the PGNSs. CONCLUSION: Collectively, such results show much promise for the use of the present PGNSs and photothermal therapy for numerous anti-cancer applications.

Synthesis and biological evaluation of novel urea, thiourea and squaramide diastereomers possessing sugar backbone.

A series of novel chiral 14 urea, thiourea and squaramide stereoisomers possessing carbohydrate backbones as well as amide functional groups was synthesized and characterized by their, 1H NMR, 13C NMR, FT-IR, HRMS, optical rotation, and melting points. Their antiproliferative activities were investigated against HeLa and PC3 cell lines. The compounds 9, 11 and 12 showed better activities at 25 µM against PC3 cell line with respect to the standard 5-fluorouracil (5-FU). Especially, the compounds 9 and 11 showed higher activities than the standard 5-FU even at low concentration (5 µM) against HeLa cell line. IC50 results also confirm these activities. The compounds 9, 10 and 11 have the IC50 values of 1.10 µM, 1.51 µM and 1.02 µM, respectively while 5-FU has 2.51 µM. Moreover, their cytotoxicity tests have proven that their viabilities were in between 50% and 100%.

Synthesis and characterization of antibacterial drug loaded ß-tricalcium phosphate powders for bone engineering applications.

Powders of ß-tricalcium phosphate [ß-TCP, ß-Ca3(PO4)2] and composite powders of ß-TCP and polyvinyl alcohol (PVA) were synthesized by using wet precipitation methods. First, the conditions for the preparation of single phase ß-TCP have been delineated. In the co-precipitation procedure, calcium nitrate and diammonium hydrogen phosphate were used as calcium and phosphorous precursors, respectively. The pH of the system was varied in the range 7-11 by adding designed amounts of ammonia solution. The filtered cakes were desiccated at 80 °C and subsequently calcined at different temperatures in the range between 700-1100 °C. Later on, rifampicin form II was used to produce drug-loaded ß-TCP and PVA/ß-TCP powders. All the synthesized materials have been characterized from morphological (by scanning electron microscopy) and structural-chemical (by X-ray diffraction and Fourier transform infrared spectroscopy) point of view. The drug loading capacity of the selected pure ß-TCP powder has been assessed. The biological performance (cytocompatibility in fibroblast cell culture and antibacterial efficacy against Escherichia coli and Staphylococcus aureus) has been tested with promising results. Application perspectives of the designed drug-bioceramic-polymer blends are advanced and discussed.

In vivo imaging/detection of MRSA bacterial infections in mice using fluorescence labelled polymeric nanoparticles carrying vancomycin as the targeting agent.

This study aims to develop fluorescence labelled polymeric nanoparticle (NP) carrying vancomycin as the targeting agent for in vivo imaging of Methicillin-resistant Staphylococcus aureus bacterial infections in animal models. Maleimide functionalized 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[maleimide (polyethylene glycol)-2000] as the main was carrier matrix to prepare the NPs. A fluorescence probe, namely, poly[9,9'-bis (6″-N,N,N-trimethylammonium) hexyl) fluorene-co-alt-4,7-(2,1,3-benzothiadiazole) dibromide] was encapsulated within these NPs by ultrasonication successfully. UV-Vis spectro- photometry of the NPs showed the characteristic shifting on the peak of conjugated polymers indicating successful packaging of this compound with lipid bilayers in nanoscales. Zeta-sizer and TEM analysis showed that the prepared NPs have a diameter of 80-100 nm in a narrow size distribution. Thiolated vancomycin was synthesized and attached to the NPs as the targeting agent. FTIR and MALDI-TOF spectroscopy analysis confirmed the immobilization. The specific targeting properties of the vancomycin conjugated NPs to the target bacteria were first confirmed in in vitro bacterial cultures in which Escherichia coli was the non-target bacteria - using confocal microscopy and TEM. Imaging of bacterial infections in vivo was investigated in mice model using a non-invasive live animal fluorescence imaging technique. The results confirmed that bacterial infections can be detected using these novel polymeric NPs carrying fluorescence probes for imaging and vancomycin as the targeting agent - in vivo successfully.

Autologous stem cell-derived chondrocyte implantation with bio-targeted microspheres for the treatment of osteochondral defects.

BACKGROUND: Chondral injury is a common problem around the world. Currently, there are several treatment strategies for these types of injuries. The possible complications and problems associated with conventional techniques lead us to investigate a minimally invasive and biotechnological alternative treatment. Combining tissue-engineering and microencapsulation technologies provide new direction for the development of biotechnological solutions. The aim of this study is to develop a minimal invasive tissue-engineering approach, using bio-targeted microspheres including autologous cells, for the treatment of the cartilage lesions. METHOD: In this study, a total of 28 sheeps of Akkaraman breed were randomly assigned to one of the following groups: control (group 1), microfracture (group 2), scaffold (group 3), and microsphere (group 4). Microspheres and scaffold group animals underwent adipose tissue collection prior to the treatment surgery. Mesenchymal cells collected from adipose tissue were differentiated into chondrocytes and encapsulated with scaffolds and microspheres. Osteochondral damage was conducted in the right knee joint of the sheep to create an animal model and all animals treated according to study groups. RESULTS: Both macroscopic and radiologic examination showed that groups 3 and 4 have resulted better compared to the control and microfracture groups. Moreover, histologic assessments indicate hyaline-like cartilage formations in groups 3 and 4. CONCLUSION: In conclusion, we believe that the bio-targeted microspheres can be a more effective, easier, and safer approach for cartilage tissue engineering compared to previous alternatives.

Effects of B2O3 (boron trioxide) on colon cancer cells: our first-step experience and in vitro results.

Boron oxide (B2O3) is derived from dehydration of boric acid and is a colorless, semitransparent, crystalline compound that is moderately soluble in water. On the other hand, boron oxide is chemically hygroscopic. This gives the molecule the ability to soak up water and adhere to tissues. Boron oxide can be used locally after tumor debulking in inoperable tumors and especially when the tumor-free margin distance cannot be provided. For all these reasons we aimed to evaluate the in vitro test results of B2O3 in terms of cytotoxicity, genotoxicity, apoptosis, and necrotic effects on L929 fibroblast cells and DLD-1 colorectal adenocarcinoma cells. Our studies demonstrated that boron oxide compounds appear to be highly cytotoxic for both cell lines according to WST cell viability assay (44.22% and 18.36% on DLD-1 and L929, respectively). Although no genotoxic effects were observed, boron oxide compounds showed antiproliferative effects for both cell lines. The prepared boron oxide compounds may hold the potential to be applied locally to the remaining tissue after surgery and further research and evaluation will be needed to determine its effectiveness.

Transscleral Delivery of Bevacizumab-Loaded Chitosan Nanoparticles.

Purpose: The aim of this study was to synthesize bevacizumab-loaded nanoparticles and evaluate their effects on the treatment of posterior segment diseases via subtenon injections. Methods: Bevacizumab-loaded chitosan nanoparticles (BLCNs) were synthesized by the ionic gelation method, and their physicochemical characteristics and in vitro release profile were studied. The BLCNs were characterized using atomic force microscopy (AFM), FTIR spectroscopy, dynamic light scattering, and scanning electron microscopy. The BLCNs were delivered into rabbits' eyes via posterior subtenon injections. An immunohistochemical evaluation of the ocular tissues was performed, and the vitreous humor and serum bevacizumab levels were measured by ELISA. Results: Bevacizumab-loaded chitosan nanoparticles with a diameter of 80 to 380 nm were prepared and characterized. In vitro studies showed that after the first 5 days of the experiment, a significant increase in the drug release maintained the desired drug dosage for 3 weeks. Immunohistochemical in vivo studies revealed that there were BLCNs penetrating through the sclera. Furthermore, the intravitreal bevacizumab concentration reached a maximum concentration of 18 µg/ml, and it decreased to 6 µg/ml after only a week. Conclusion: The results revealed that subtenon injection of BLCNs is a promising alternative to intravitreal injections. In addition to the ELISA studies, immunohistochemical experiments confirmed that BLCNs enable transscleral bevacizumab penetration, and BLCN usage may provide the required bevacizumab levels for the treatment of posterior segment diseases.

Pectin-conjugated magnetic graphene oxide nanohybrid as a novel drug carrier for paclitaxel delivery.

Recent studies have shown that graphene oxide (GO) drug carrier functionalized with biocompatible natural polymers lead to higher loading efficacy and better stability with diminished cellular toxicity. Pectin (PEC) is one of the polysaccharide natural polymers, which has the potential to be used for drug delivery. In this work, we have successfully developed a novel PEC-conjugated magnetic GO nanocarrier for effective delivery of paclitaxel. The structure, surface morphology and thermal stability of the nanohybrid were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and zeta-sizer. Moreover, drug loading and release performance were studied by UV-vis absorption spectra. The cytotoxicity test was also performed by MTT test using L-929 fibroblast normal cell and MCF-7 cancer lines. The prepared nanocarrier showed an improved stability with enhanced drug loading capacity. Additionally, pH-responsive release analysis of the nanohybrid illustrated higher drug release at endosomal pH of cancer cell than that of normal physiological environment. Besides, cytotoxicity test demonstrated the synthesized nanohybrid is biocompatible, having very high relative cell viability. Bearing in mind these findings, the designed multifunctional nanohybrid drug carrier will be a good candidate for cancer drug delivery.

Modified gold-based siRNA nanotherapeutics for targeted therapy of triple-negative breast cancer.

AIM: In this study, we aimed to therapeutically target eukaryotic elongation factor 2 kinase (eEF-2K) in an in vivo triple-negative breast cancer (TNBC) tumor model. MATERIALS & METHODS: We synthesized a highly monodisperse nanoformulation using polyethylenimine-modified gold nanoparticles (AuNP-PEI) as siRNA delivery vehicle and evaluated gene downregulation. RESULTS: We found that AuNP-PEI/eEF-2K nanoformulation was highly effective for in vitro and in vivo gene downregulation and showed remarkable antitumor efficacy that was associated with eEF-2K knockdown, inhibition of Src and MAPK-ERK signaling pathways in a TNBC orthotopic tumor model. CONCLUSION: Our study suggests that eEF-2K plays an important role in TNBC tumorigenesis and its inhibition by AuNP-PEI/eEF-2K siRNA-based nanotherapeutics may be a potential therapeutic strategy for TNBC.

Multiwalled Carbon Nanotube-Chitosan Scaffold: Cytotoxic, Apoptoti c, and Necrotic Effects on Chondrocyte Cell Lines.

BACKGROUND: Carbon nanotubes (CNTs) have been considered highly successful and proficient in terms of their mechanical, thermal and electrical functionalization and biocompatibility. In regards to their significant extent in bone regeneration, it has been determined that CNTs hold the capability to endure clinical applications through bone tissue engineering and orthopedic procedures. In the present study, we report on a composite preparation, involving the use of CNT-chitosan as scaffold for bone repair and regeneration. Through the use of water-soluble tetrazolium salt (WST-1) and double staining methods, the cytotoxic, necrotic, and apoptotic effects of chitosan-multiwalled carbon nanotube nanocomposites on the chondrocyte ATTC cell line have been exhibited. METHODS: The chitosan-multiwalled carbon nanotube scaffolds were prepared. Chondrocytes differentiation tool (ATCC) cell line was prepared. WST-1 assay for cytotoxicity studies were performed by using chondrocytes cells in 12.5-200 µL concentration range. The samples of membranes (chitosan- multiwalled carbon nanotube scaffold) were measured at 2 mg/mL and further prepared amongst chitosan- multiwalled carbon nanotube scaffold's which were placed into separate wells. While in the process of incubation, in the four-hour time range, the plates were immediately read in an Elisa microplate Reader. To predict the number of apoptotic and necrotic cells in culture, the technique of double staining with Hoechst dye was performed with PI on the basis of scoring cell nuclei. The mechanical properties such as tensile strength and elongation at break values of the chitosan only and chitosan/CNT scaffolds were evaluated on Texture Analyzer. RESULTS: Based on the results of the WST-1 assay procedure, the amount of cell viability was not significantly affected by nanocomposite concentrations and the lowest mortality rate of cells was obtained at a concentration of 12.5 µg/mL, whereas the highest mortality rate was obtained at a rate of 200 µg/mL. In addition, the effects of chitosan-CNT nanocomposites were not found to cytotoxic on chondrocyte cells. The double staining method has been able to determine the apoptotic and necrotic effects of chitosan MWCNT nanocomposites. The apoptotic and necrotic effects of the combined compounds had varied within the concentrations. In a similar manner to the outcome of the control groups, apoptosis was obtained at a percentage of 2.67%. Under a fluorescent inverted microscope, the apoptotic cell nuclei were stained with a stronger blue fluorescence in comparison to non-apoptotic cells, which may have had an effect. We also compared the strain-stress curve measurements results. The results indicated that the mechanical properties of scaffold were not different. Elongation at break values increased by addition of CNT. CONCLUSION: CNTs as a biomaterial hold the potential to be used for applications in future regenerative medicine. By using the components of chondrocytes (ATTC) cell lines, the cytotoxicity evaluations were made for the chitosan-multiwalled carbon nanotube scaffold. The chitosan-MWCNT nanocomposites do not seem to induce drastic cytotoxicity to the chondrocyte cells.

Synthesis, characterization and modification of Gum Arabic microgels for hemocompatibility and antimicrobial studies.

Gum Arabic (GA) microgels were successfully prepared via reverse micellization method with high yield (78.5±5.0%) in 5-100µm size range using divinyl sulfone (DVS) as a crosslinker. The GA microgels were degraded hydrolytically 22.8±3.5% at pH 1 in 20days, whereas no degradation was observed at pH 7.4 and pH 9 at 37°C. By using diethylenetriamine (DETA), and taurine (TA) as chemical modifying agents, GA microgels were chemically modified as GA-DETA and GA-TA, and the zeta potential values of 5.2±4.1 and -24.8±1.3mV were measured, respectively in comparison to -27.3±4.2mV for GA. Moreover, blood compatibility of GA, GA-TA, and GA-DETA microgels was tested via in vitro protein adsorption, % hemolysis ratio, and blood clotting index. All the microgels were hemocompatible with% hemolysis ratio between 0.23 to 2.05, and the GA microgels were found to be highly compatible with a blood clotting index of 81±40. The biocompatibility of GA, GA-DETA and GA-Taurine microgels against L929 fibroblast cells also revealed 84.4, 89.1, and 67.0% cell viability, respectively, at 25.0µg/mL concentration, suggesting great potential in vivo biomedical applications up to this concentration. In addition, 5 and 10mg/mL minimum inhibition concentrations of protonated GA-DETA microgels (GA-DETA-HCl) were determined against E. coli and S. aureus, respectively.

Bi-layered constructs of poly(glycerol-sebacate)-ß-tricalcium phosphate for bone-soft tissue interface applications.

This study aims to establish a facile protocol for the preparation of a bi-layered poly(glycerol-sebacate) (PGS)/ß-tricalcium phosphate (ß-TCP) construct and to investigate its potential for bone-soft tissue engineering applications. The layered structure was prepared by distributing the ceramic particles within a prepolymer synthesized in a microwave reactor followed by a cross-linking of the final construct in vacuum (<10mbar). The vacuum stage led to the separation of cross-linked elastomer (top) and ceramic (bottom) phases. Results showed that addition of ß-TCP particles to the elastomer matrix after the polymerization led to an increase in compression strength (up to 14±2.3MPa). Tensile strength (σ), Young's modulus (E), and elongation at break (%) values were calculated as 0.29±0.03MPa and 0.21±0.03; 0.38±0.02 and 1.95±0.4; and 240±50% and 24±2% for PGS and PGS/ß-TCP bi-layered constructs, respectively. Morphology was characterized by using Scanning Electron Microscopy (SEM) and micro-computed tomography (µ-CT). Tomography data revealed an open porosity of 35% for the construct, mostly contributed from the ceramic phase since the elastomer side has no pore. Homogeneous ß-TCP distribution within the elastomeric structure was observed. Cell culture studies confirmed biocompatibility with poor elastomer-side and good bone-side cell attachment. In a further study to investigate the osteogenic properties, the construct were loaded with BMP-2 and/or TGF-ß1. The PGS/ß-TCP bi-layered constructs with improved mechanical and biological properties have the potential to be used in bone-soft tissue interface applications where soft tissue penetration is a problem.

The effect of calcium chloride concentration on alginate/Fmoc-diphenylalanine hydrogel networks.

Peptide based hydrogels gained a vast interest in the tissue engineering studies thanks to great superiorities such as biocompatibility, supramolecular organization without any need of additional crosslinker, injectability and tunable nature. Fmoc-diphenylalanine (FmocFF) is one of the earliest and widely used example of these small molecule gelators that have been utilized in biomedical studies. However, Fmoc-peptides are not feasible for long term use due to low stability and weak mechanical properties at neutral pH. In this study, Fmoc-FF dipeptides were mechanically enhanced by incorporation of alginate, a biocompatible and absorbable polysaccharide. The binary hydrogel is obtained via molecular self-assembly of FmocFF dipeptide in alginate solution followed by ionic crosslinking of alginate moieties with varying concentrations of calcium chloride. Hydrogel characterization was evaluated in terms of morphology, viscoelastic moduli and diffusional phenomena and the structures were tested as 3D scaffolds for bovine chondrocytes. In vitro evaluation of scaffolds lasted up to 14days and cell viability, sulphated glycosaminoglycan (sGAG) levels, collagen type II synthesis were determined. Our results showed that alginate incorporation into FmocFF hydrogels leads to better mechanical properties and higher stability with good biocompatibility.

Fabrication and characterization of PVA/ODA-MMT-poly(MA-alt-1-octadecene)-g-graphene oxide e-spun nanofiber electrolytes and their response to bone cancer cells.

This work presents a new approach to fabrication and characterization of novel polymer nanofiber electrolytes from intercalated PVA/ODA-MMT nanocomposite as a matrix polymer and encapsulated graphene oxide (GO) nanosheets with amphiphilic reactive copolymer as partner polymers using electrospinning method. The chemical and physical structures, surface morphology, thermal behaviors and electric conductivity of nanocomposites and nanofibers were investigated using analyses methods including FTIR, XRD, SEM, DSC-TGA and conductivity analysis. Significant improvements in nanofiber morphology and size distribution were observed when GO and reactive organoclay were incorporated as reinforcement fillers into various matrix/partner solution blends. The structural factors of matrix-partner polymer nanocomposite particles with higher zeta-potential play important roles in both chemical and physical interfacial interactions and phase separation processing and also lead to the formation of nanofibers with unique surface morphologies and good conductivities. The cytotoxic, necrotic and apoptotic effects of chosen nanofibers on osteocarcinoma cells were also investigated. These multifunctional, self-assembled, nanofibrous surfaces can serve as semi-conductive and bioactive platforms in various electrochemical and bio-engineering processes, as well as reactive matrices used for the immobilization of various biopolymer precursors.