Basaran, D. D. A., Gunduz, U., Tezcaner, A., and Keskin, D. (2021). Topical delivery of heparin from PLGA nanoparticles entrapped in nanofibers of sericin/gelatin scaffolds for wound healing. International Journal of Pharmaceutics, 597, 120207. DOI: 10.1016/j.ijpharm.2021.120207

Skin regeneration is one of the most important issues in tissue engineering. Research on more effective biomaterials that will enhance regeneration while enabling requirements of a healing skin site is an important challenge in skin tissue engineering. In this study, heparin was encapsulated in Poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) which were then incorporated into Sericin/Gelatin (Ser/Gel) nanofibers during the electrospinning process in order to develop a combined system that has controlled release approach, besides the ability to help the regeneration of skin tissue by the involvement of biopolymers; gelatin, and sericin. The loading capacity and heparin encapsulation efficiency in the nanoparticles were determined as 30.04 mg/g of polymer and 60%, respectively. Cumulative release of heparin from NPs for 1 week was faster than from NPs loaded gelatin scaffolds and from dual protein (Ser/Gel) scaffolds with ratios: 1/7 and 1/2 (approximately 85%, 65%, 55%, and 40%, respectively). Sericin addition slowed down the degradation properties of the scaffold. The scaffold having a Ser/Gel ratio (1/2) was found as the most promising candidate because of its proper fiber morphology, high water retention, and low degradation degree.

Motameni, A., Alshemary, A. Z., Dalgic, A. D., Keskin, D., and Evis, Z. (2021). Lanthanum doped dicalcium phosphate bone cements for potential use as filler for bone defects. Materials Today Communications, 26, 101774. DOI: 10.1016/j.mtcomm.2020.101774

The bone defects arising as a result of trauma should be filled to provide a framework to support and encourage the growth of new and living bone tissues. Among the many synthetic bone graft substitutes, self-hardening calcium phosphate (CP) cements have been widely used to repair hard tissue defects. In this study, pure dicalcium phosphate (DCP) and lanthanum (La) modified dicalcium phosphate (La-DCP) bone cements were prepared based on acid/base reaction between β- tricalcium phosphate (βTCP) (or La- βTCP) and monocalcium phosphate monohydrate (MCPM) in the presence of water. The prepared bone cements were characterized using XRD, FTIR and SEM techniques to verify both La doping and to explore the alterations in the structural and molecular properties upon doping. With minimum addition of La3+ ions (0.090 mol), the pure phase of brushite transformed into monetite and the plate-like crystals of brushite turned into spheroid particles. The setting times of DCP bone cement declined gradually upon boosting amount of La3+ ions in DCP lattice. As the La amount in DCP cements rose from 0 to 0.225 mol, the compressive strength also increased from 7.90 ± 0.8 to 9.64 ± 1.47 MPa. The dissolution rate of DCP cements improved with addition of La3+ ions. Adsorption/desorption of Fetal bovine serum (FBS) on/from the prepared DCP bone cements showed higher protein loading of La-DCP cements than pure DCP. In vitro experiments on proliferation, adhesion, and osteogenic differentiation of Sarcoma osteogenic (Saos-2) cells indicated that addition 0.225 mol of La3+ ions promoted these properties compared to pure DCP. Results suggested that La3+ (0.225 mol) incorporated DCP bone cement (2La-DCP) has a potential to be used as a bone filler material.

Pazarçeviren, A. E., Tezcaner, A., Keskin, D., Kolukısa, S. T., Sürdem, S., & Evis, Z. (2021). Boron-doped biphasic hydroxyapatite/β-tricalcium phosphate for bone tissue engineering. Biological Trace Element Research, 199(3), 968-980. DOI: 10.1007/s12011-020-02230-8

Boron-doped hydroxyapatite/tricalcium phosphates (BHTs) were synthesized to study boron uptake and correlate structural alterations of incremental boron addition (0 to 10 mol%). BHTs with a Ca/P ratio of 1.6 were prepared by a wet precipitation/microwave reflux method, sieved (< 70 μm) and characterized. XRD and FTIR analyses revealed that boron slightly distorted apatite crystal, increased crystallinity (95.78 ± 2.08% for 5BHT) and crystallite size (103.39 ± 23.47 nm for 5BHT) and still, boron addition did not show any further detrimental effects. Total surface area (4.05 ± 0.82 m2/g for 10BHT) and mesoporosity (23.90 ± 7.92 μL/g for 10BHT) were expanded as boron content was increased. Moreover, boron addition made grains become smaller (0.21 ± 0.06 μm for 5BHT) and ordered while hardness (10.51 ± 0.86 GPa for 10BHT) increased. Boron incorporation enhanced bioactivity with significantly highest calcium phosphate deposition and protein adsorption (135.29 ± 29.58 μg on 10BHT). In return, boron favored highest alkaline phosphatase activity (4.80 ± 0.40 MALP/ngDNA.min), intracellular calcium (23.61 ± 0.68 g/gDNA), phosphate (31.84 ± 4.68 g/gDNA), and protein (23.70 ± 3.46 g/gDNA) storage in 5BHT without cytotoxicity (128 ± 18% viability compared to pure HT). Compared to literature, it can be pointed out that we successfully employed an optimal procedure for production of BHTs and incorporated significantly higher boron content in HT (5.23 mol%). Additionally, results tended to conclude that 5BHT samples (5 mol% boron in HT) demonstrated a very high potential to be used in composite bone tissue constructs.

Erener, T., Ceritoğlu, K. U., Aktekin, C. N., Dalgic, A. D., Keskin, D., Geneci, F., et al. (2021). Investigation of The Effect of Ghrelin on Bone Fracture Healing in Rats. Clinical and Experimental Pharmacology and Physiology. DOI: 10.1111/1440-1681.13544

Ghrelin is known to have effects on proliferation and differentiation of osteoblasts and improvement of bone mineral density in rats. However, no experimental research on ghrelin's effects on fracture healing has been reported. In this context, the effect of ghrelin on the union of femoral shaft fractures was examined in this study by evaluating whether ghrelin will directly contribute to fracture healing. Forty male Wistar-Albino rats were divided into two groups as control and experimental (ghrelin treated) and standard closed shaft fractures were created in the left femurs of all rats. Daily ghrelin injections were applied to the experimental groups and equal numbers of rats were killed after 14 and 28 days following fracture formation. Tissue samples were examined with radiological, biomechanical, biochemical and histological analyses. Densitometry study showed that bone mineral density was improved after 28 days of ghrelin treatment compared to control. On histological examination, at the end of the 14 and 28 days of recovery, significant union was observed in the ghrelin-treated group. The ghrelin-treated group had higher breaking strength and stiffness at the end of 28 days of recovery. Biochemically, ALP levels were found to be higher in the ghrelin-treated group at the end of 28 days of recovery. Results showed that ghrelin directly contributes to fracture healing and it is promising to consider the effect of ghrelin on fracture healing in human studies with pharmacological applications.

Dalgic, A. D., Koman, E., Karatas, A., Tezcaner, A., and Keskin, D. (2021). Natural origin bilayer pullulan-PHBV scaffold for wound healing applications. Materials Science and Engineering: C, 112554. DOI: 10.1016/j.msec.2021.112554

Skin tissue loss that occurs by injury and diseases can turn into chronic wounds as a result of complications alongside infection. Chronic wounds fail to heal by themselves and need advanced treatments like engineered wound dressings and regenerative scaffolds. In this study, a novel, natural origin, bilayer electrospun scaffold was produced from pullulan (PUL) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) biopolymers. PHBV production by Cupriavidus necator bacterial strain was optimized and produced polymer was characterized. Characteristic peaks and bands of PHBV were observed by H-NMR and FTIR analyses. Valerate mol percent of produced PHBV copolymer was determined by H-NMR. Average molecular weight of the polymer was determined by SLS technique and crystallinity of PHBV was calculated from DSC curve. Bilayer scaffold was produced by electrospinning of hydrophilic PUL fibrous membrane onto wet-electrospun hydrophobic PHBV 3D fibrous mat. Bilayer scaffold was designed to involve regenerative and barrier fibrous layers. Nano fibrous PUL membrane with smaller pore size was efficient as a barrier against bacterial transmission while enabling optimum oxygen and water vapor transmission. Water retention and degradation properties were found to be optimum for a skin tissue scaffold. In vitro studies showed that PUL membrane sustained L929 cell proliferation while preventing cells from migrating inside the barrier phase while PHBV layer supported cell viability, proliferation, and migration, creating a regenerative 3D structure. Results showed that, novel natural origin PUL/PHBV bilayer scaffold is a promising candidate for wound healing applications.

Akbaba, S., Atila, D., Keskin, D., Tezcaner, T., and Tezcaner, A. (2021). Multilayer fibroin/chitosan oligosaccharide lactate and pullulan immunomodulatory patch for treatment of hernia and prevention of intraperitoneal adhesion. Carbohydrate Polymers, 265, 118066. DOI: 10.1016/j.carbpol.2021.118066

This study aims to develop a novel intraperitoneal two- or three-layered patch with immunomodulatory property for treatment of hernia, regeneration of abdominal wall and prevention of intraperitoneal adhesions. Polypropylene (PP) mesh, middle layer, was intended to provide mechanical support whereas pullulan (PUL) hydrogel coating layer was designed to prevent intraperitoneal adhesions. Fibroin/chitosan oligosaccharide lactate (F/COS) layer electrospun on one side of pullulan was chosen for immunomodulation and abdominal wall regeneration. Physical and mechanical properties and regenerative capacity of intraperitoneal patches were determined. Immunomodulatory property of electrospun layer and whole patch was studied by determining nitric oxide amount produced by RAW 264.7 macrophages. 25 % (w/v) PUL hydrogel and F/COS with 90:10 (w/w) ratio yielded optimal results. Here, we report that fabricated intraperitoneal patches successfully prevented cell adhesion on one side and increased cell viability and proliferation on other side, along with immunomodulation, in vitro.

Pazarceviren, A. E., Tezcaner, A., and Evis, Z. (2021). Multifunctional natural polymer-based metallic implant surface modifications. Biointerphases, 16(2), 020803. DOI: 10.1116/6.0000876

High energy traumas could cause critical damage to bone, which will require permanent implants to recover while functionally integrating with the host bone. Critical sized bone defects necessitate the use of bioactive metallic implants. Because of bioinertness, various methods involving surface modifications such as surface treatments, the development of novel alloys, bioceramic/bioglass coatings, and biofunctional molecule grafting have been utilized to effectively integrate metallic implants with a living bone. However, the applications of these methods demonstrated a need for an interphase layer improving bone-making to overcome two major risk factors: aseptic loosening and peri-implantitis. To accomplish a biologically functional bridge with the host to prevent loosening, regenerative cues, osteoimmunomodulatory modifications, and electrochemically resistant layers against corrosion appeared as imperative reinforcements. In addition, interphases carrying antibacterial cargo were proven to be successful against peri-implantitis. In the literature, metallic implant coatings employing natural polymers as the main matrix were presented as bioactive interphases, enabling rapid, robust, and functional osseointegration with the host bone. However, a comprehensive review of natural polymer coatings, bridging and grafting on metallic implants, and their activities has not been reported. In this review, state-of-the-art studies on multifunctional natural polymer-based implant coatings effectively utilized as a bone tissue engineering (BTE) modality are depicted. Protein-based, polysaccharide-based coatings and their combinations to achieve better osseointegration via the formation of an extracellular matrix-like (ECM-like) interphase with gap filling and corrosion resistance abilities are discussed in detail. The hypotheses and results of these studies are examined and criticized, and the potential future prospects of multifunctional coatings are also proposed as final remarks.

Alshemary, A. Z., Bilgin, S., Işık, G., Motameni, A., Tezcaner, A., and Evis, Z. (2021). Biomechanical Evaluation of an Injectable Alginate/Dicalcium Phosphate Cement Composites for Bone Tissue Engineering. Journal of the Mechanical Behavior of Biomedical Materials, 118, 104439. DOI: 10.1016/j.jmbbm.2021.104439

Biocompatible dicalcium phosphate (DCP) cements are widely used as bone repair materials. In this study, we aimed to investigate the impact of different amounts of sodium alginate (SA) on the microstructural, mechanical, and biological properties of DCP cements. Beta-tricalcium phosphate (β-TCP) was prepared using a microwave-assisted wet precipitation system. Lattice parameters of the obtained particles determined from X-ray diffraction (XRD), were in good match with a standard phase of β-TCP. Scanning electron microscopy (SEM) examination revealed that the particles were in globular shape. Furthermore, all functional groups of β-TCP were also detected using Fourier-transform infrared spectroscopy (FTIR) spectra. DCP cement (pure phase) was synthesized using monocalcium phosphate monohydrate (MCPM)/β-TCP powder mixture blended with 1.0 mL of water. SA/DCP cement composites were synthesized by dissolving different amounts of SA into water (1.0 mL) to obtain different final concentrations (0.5%, 1%, 2% and 3%). The prepared cements were characterized with XRD, SEM, FTIR and Thermogravimetric analysis (TGA). XRD results showed that pure DCP and SA/DCP cements were in a good match with Monetite phase. SEM results confirmed that addition of SA inhibited the growth of DCP particles. Setting time and injectability behaviour were significantly improved upon increasing the SA amount into DCP cements. In vitro biodegradation was evaluated using Simulated body fluid (SBF) over 21 days at 37 °C. The highest cumulative weight loss (%) in SBF was observed for 2.0% SA/DCP (about 26.52%) after 21 days of incubation. Amount of Ca2+ ions released in SBF increased with the addition of SA. DCP and SA/DCP cements showed the highest mechanical strength after 3 days of incubation in SBF and declined with prolonged immersion periods. In vitro cell culture experiments were conducted using Dental pulp stem cells (DPSCs). Viability and morphology of cells incubated in extract media of DCP and SA/DCP discs after 24 h incubation was studied with MTT assay and fluorescence microscopy imaging, respectively. All cements were cytocompatible and viability of cells incubated in extracts of cements was higher than observed in the control group. Based on the outcomes, SA/DCP bone cements have a promising future to be utilized as bone filler.

Yedekci, B., Tezcaner, A., Alshemary, A. Z., Yılmaz, B., Demir, T., and Evis, Z. (2021). Synthesis and sintering of B, Sr, Mg multi-doped hydroxyapatites: Structural, mechanical and biological characterization. Journal of the Mechanical Behavior of Biomedical Materials, 115, 104230. DOI: 10.1016/j.jmbbm.2020.104230

Hydroxyapatite (HA, Ca10(PO4)6(OH)2) is the main constituent mineral of bone and teeth in mammals. Due to its outstanding biocompatibility and osteoconductive capabilities, it is preferred for bone repair and replacement. Owing to high potential to have excellent biological properties, ternary ions-doped HAs have just begun to be investigated in the biomedical field and preparing multi-doped HAs is a fairly new approach. Boron (B, BO33-), strontium (Sr, Sr2+) and magnesium (Mg, Mg2+) provide a beneficial effect on bone growth, bone strength, biocompatibility and positively affect bone microstructure. The motivation of this study is taking advantages of the potential of the combine effects of these bivalent ions. In this study, 8 different compositions of BO33-, Sr2+, Mg2+ multi-doped HAs were synthesized by microwave irradiation method to investigate the structural, mechanical and biological features of bone substitutes. This is the first time we report the effect of boron, strontium and magnesium ions multi-doping on the structure of HA and its biological properties. Samples were sintered at 700, 900 and 1100 °C. The effect of varying ion contents and sintering temperature on structural and biological properties of the multi-doped samples was investigated. B, Sr and Mg ions were successfully doped into the HA structure according to X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) analyses. A biphasic structure was obtained with increasing amount of ion-doping. Increasing the sintering temperature affected the crystallinity and the density of the samples gradually. Vicker's microhardness and diametral strength of the samples increased at high sintering temperatures. B–Sr–Mg multi-doped HA promoted osteoblast-like Saos-2 cell proliferation, and as the sintering temperatures of the samples increased, the osteogenic differentiation level of the cultured cells also increased. Overall, results showed that the biological properties of HA were improved with the doping of Sr, Mg and B ions, and for bone implant applications samples sintered at 1100 °C were suggested to have potential as a biomaterial.


Last Updated:
03/01/2022 - 15:57