Ozan Karaman

Synergistic Effect of Cold Plasma Treatment and RGD Peptide Coating on Cell Proliferation over Titanium Surfaces

The aim of this study was to investigate the synergistic effect of cold atmospheric plasma (CAP) treatment and RGD peptide coating for enhancing cellular attachment and proliferation over titanium (Ti) surfaces. The surface structure of CAP-treated and RGD peptide-coated Ti discs were characterized by contact angle goniometer and atomic force microscopy. The effect of such surface modification on human bone marrow derived mesenchymal stem cells (hMSCs) adhesion and proliferation was assessed by cell proliferation and DNA content assays. Besides, hMSCs’ adhesion and morphology on surface modified Ti discs were observed via fluorescent and scanning electron microscopy. RGD peptide coating following CAP treatment significantly enhanced cellular adhesion and proliferation among untreated, CAP-treated and RGD peptide-coated Ti discs. The treatment of Ti surfaces with CAP may contribute to improved RGD peptide coating, which enables increased cellular integrations with the Ti surfaces.

Modification of electrospun PVA/PAA scaffolds by cold atmospheric plasma: alignment, antibacterial activity, and biocompatibility

The ongoing search for better antibacterial wound care dressings has led to the design and fabrication of advanced functional nanomaterials. Taking advantage of electrospinning and cold atmospheric plasma (CAP), free-standing nanofibrous scaffolds are promising for use in novel biomedical applications. Random and aligned polyvinyl alcohol (PVA)/polyacrylic acid (PAA) nanofiber scaffolds are fabricated by electrospinning and treated with CAP. In this study, we investigate the effects of CAP treatment on alignment, hydrophilicity, antibacterial activity, and biocompatibility in determining the surface properties of the nanofibrous scaffolds. The results of vibrational polarization spectroscopy analysis indicate that CAP treatment changes the degree of alignment of the nanofibers. Furthermore, both random and aligned CAP-treated nanofibrous scaffolds show significant antibacterial activity against the E. coli strain. The results of an in vitro scratch assay reveal that CAP treatment of PVA/PAA nanofibers has no toxic effect.

Prevention of bacterial colonization on non-thermal atmospheric plasma treated surgical sutures for control and prevention of surgical site infections

Surgical site infections have a remarkable impact on morbidity, extended hospitalization and mortality. Sutures strongly contribute to development of surgical site infections as they are considered foreign material in the human body. Sutures serve as excellent surfaces for microbial adherence and subsequent colonization, biofilm formation and infection on the site of a surgery. Various antimicrobial sutures have been developed to prevent suture-mediated surgical site infection. However, depending on the site of surgery, antimicrobial sutures may remain ineffective, and antimicrobial agents on them might have drawbacks. Plasma, defined as the fourth state of matter, composed of ionized gas, reactive oxygen and nitrogen species, free radical and neutrals, draws attention for the control and prevention of hospital-acquired infections due to its excellent antimicrobial activities. In the present study, the efficacy of non-thermal atmospheric plasma treatment for prevention of surgical site infections was investigated. First, contaminated poly (glycolic-co-lactic acid), polyglycolic acid, polydioxanone and poly (glycolic acid-co-caprolactone) sutures were treated with non-thermal atmospheric plasma to eradicate contaminating bacteria like Staphylococcus aureus and Escherichia coli. Moreover, sutures were pre-treated with non-thermal atmospheric plasma and then exposed to S. aureus and E. coli. Our results revealed that non-thermal atmospheric plasma treatment effectively eradicates contaminating bacteria on sutures, and non-thermal atmospheric plasma pre-treatment effectively prevents bacterial colonization on sutures without altering their mechanical properties. Chemical characterization of sutures was performed with FT-IR and XPS and results showed that non-thermal atmospheric plasma treatment substantially increased the hydrophilicity of sutures which might be the primary mechanism for the prevention of bacterial colonization. In conclusion, plasma-treated sutures could be considered as novel alternative materials for the control and prevention of surgical site infections.

Integrin binding peptide promotes in vitro wound closure in the L929 mouse fibroblasts

Objective. Molecular basis of wound healing process needs to further examined to determine the effective individual biological cues. The objective of this study was to investigate the wound closure, proliferation, and viability of L929 fibroblast when cultured with different concentration of soluble RGD peptid. Methods. RGD peptide was synthesized manually on solid phase. The percentage of healed wound area for control, 0.5 mM, 1 mM, and 2 mM at each time points were analyzed by ImageJ. Cell proliferation and viability were assessed with MTT and live/ dead analysis, respectively. Results. The results of wound closure area showed that increased RGD peptide concentration in the culture improved cellular migration which enables significantly accelerated wound closure. However, RGD peptide did not dramatically augmented cell proliferation. In addition, cell viability results indicated that dead cell numbers did not critically influence by increasing the RGD peptide concentration in the culture. Conclusions. The present study showed that soluble integrin binding peptide accelerated the migration and wound closure rate of L929 fibroblasts. Delivery of soluble integrin binding peptides into the wound area may be considered as an alternative wound treatment technique in the near future after proofing the concept study with animal and clinical studies.

Determination of minimum serum concentration to develop scaffold free micro-tissue

Objective. Formation of three-dimensional (3D) micro-tissues without scaffolds are widely used not only to define in vivo tissue formation mechanisms but also the development of different tissue-specific drugs. However, depending on high serum and growth factor concentrations, it would be hard to identify major effective biological cues on micro-tissue formation. The aim of the study is to determine the effect of different serum concentrations on Human Umbilicial Vein Endothelial Cells (HUVECs) micro-tissue formation. Methods. Micro-tissue of HUVEC line was formed by using 3D petri dish technique with medium containing 0%, 1%, 5% and 10% fetal bovine serum (FBS). On the 7 th day after micro-tissue formation, live/dead cells analysis was conducted. Micrograph taken on days 1, 3, 5 and 7 th of micro-tissue formation were determined by image analysis with ImageJ. Results. Sizes of micro-tissue formed with 0% FBS on day 1 and 3 determined as 277 ± 12 µm and 279 ± 20 µm, respectively; however, especially on day 7 micro-tissue size significantly decreased to 229 ± 6 µm. When live/dead analysis results were examined, high cell viability was observed in 5% and 10% FBS concentration. Although micro-tissue like structures were observed in 0% and 1% FBS concentrations dead cell ratio considerably increased compared to 5% and 10% FBS concentration. Conclusions. It has been determined that 0% and 1% serum are appropriate for determining the efficacy of biomimetic peptides and different extracellular matrix proteins on micro-tissue formation parameters of HUVEC. High cell viability in micro-tissues was observed with 5% and 10% serum concentrations.

Effects of Pulsed Electromagnetic Fields on the of 3T3 fibroblast cells

Pulsed Electromagnetic Fields (PEMFs), are usually low-frequency fields with very specific wave shapes and amplitude, have been shown to accelerate wound healing and are used in adjuvant therapy. Also Pulsed Radio Frequency Energy (PRFE) is another term for this therapy that delivers electromagnetic signals to a target tissue without the intended generation of deep heat. Although the exact mechanism of action on wound healing is still unclear, it is known both treatment have effect on cell proliferation and migration. The present study examined the effect of PEMF (75 Hz frequency, square waveform, and 1-mT magnetic field) and PRFE (27.12 MHz, amplitude modulation (AM), and 13-dBm amplitude signal) treatments on an in vitro wound healing model using by 3T3 mouse fibroblast cells.

Development of innovative custom design bioprinter

In this study, the custom design of this bioprinter was designed by using the 3D printing technology and it was tested to print biotechnological samples, which made up of hydrogel (PEGDA) single layer with different shapes and sizes. The custom designed printer is fully controlled by computer programming, that allows printing in accurate way and make our target closed to be fulfilled to print, in future, more complicated biological tissues and organs. The bioprinter was built using an effective and modern technologies as we simultaneously were improving the mechanical design and testing it right away. At such a rate, we will soon be able to make our first attempts to print more complex structures which will give us a better view on how effective our bioprinter is. The custom designed bioprinter will be facile, affordable and accessible by all people with different backgrounds and experiences.

The efficacy of using RGD peptide sequence on in vitro wound healing

In scientific area, many different studies are carried out to ensure the development of more effective and rapid wound healing method. Applied and developed several methods aims rapid wound healing with minimal discomfort to the patient which is also allow the movement of epithelial cells and to allow the regeneration of cells during to wound healing process with provided the ideal environment. It is known that RGD peptide sequences can support cell regeneration and increase cell adhesion by activating integrins therewithal synthesis of the peptide sequence simple and low cost, researchs in this field has gained momentum in recent years. The present study examined the effect of culture medium contain peptide sequence with concentration of 0.1 mg/ml and 0.5 mg/ml, on an in vitro wound healing model using by L929 fibroblast cells.

The evaluation of wettability and cell-surface interactions on modified titanium discs with Atmospheric Cold Plasma application and RGD peptide conjugation: In vitro study

Besides the material type, surface characteristics of titanium based dental implants also affect the treatment success and time. Atmospheric Cold Plasma (ACP) treatment and RGD peptide conjugation methods are applied to titanium implants for shortening the osseointegration time by increasing the surface hydrophilicty and cell adhesion rate. However the comparative effect of these two implant surface modification techniques has yet to be investgated. In the scope of this study, efficacy of the ACP treatment and RGD peptide conjugation methods has been evaluated by determining adhesion and proliferation of rat bone marrow mesencymal stem cells (MSC) on the surface of modified implants. It was shown that comparing the usage of two individual surface modifications, RGD peptid conjugation after ASP treatment of the implant surface had significantly higher MSC adhesion and proliferation.

Fabrication and characterization of osteon mimetic microtubular scaffolds for bone tissue engineering application

In the scope of bone tissue engineering, there has still been great amount of demand on designing biomimetic scaffolds that induces differentiation of osteoprogenitor cells by cell-matrix interaction at the nanoscale as well as mimicking micro assembly of compact bone while providing high mechanical strength. In this study, in order to use in the treatment of large bone defects, osteon mimetic 3D microtubular scaffolds were developed by using mineralized nanofiber sheets and characterized. The main goal for designing microtubular scaffolds is to mimic the nano and micro structures of bone tissue.