Browsing by Subject "Hydrogel"

Now showing 1 - 9 of 9

Open Access
Bioactive peptide nanofibers for acceleration of burn wound healing
(2017-05) Yergöz, Fatih
Burn injuries are one of the most typical types of trauma worldwide, and the unique physiology of burn injuries requires the use of specialized therapeutic materials for treatment and makes the development of such materials especially challenging. Here, we report the use of synthetic, functional and biodegradable peptide nanofiber gels for improved healing of burn wounds to alleviate the progressive loss of tissue function at the post-burn wound site. These bioactive nanofiber gels form scaffolds which recapitulate the morphology and function of the natural extracellular matrix through peptide epitopes, which can trigger angiogenesis through significant affinity to basic growth factors. In this study, the angiogenesis-promoting properties of the bioactive scaffolds were utilized for the treatment of thermal burn model. Following the excision of necrotic tissue, bioactive gels and control solutions were applied topically onto the wound area. The wound healing process was evaluated at 7, 14 and 21 days following injury through histological observations, immunostaining and marker RNA / protein analysis. Bioactive peptide nanofiber treated burn wounds formed well-organized and collagen-rich granulation tissue layers, developed a greater density of newly formed blood vessels, and exhibited increased re-epithelialization and skin appendage formation with minimal crust formation. Overall, the heparin-mimetic peptide nanofiber gels increased the rate of repair of burn injuries and can be used as effective means of facilitating wound healing.
Open Access
Bioactive porous peg-peptide composite hydrogels with tunable mechanical properties
(2014) Göktaş, Melis
Mimicking the instructive cues of native extracellular matrix (ECM) is fundamental to understand and control the processes regulating cell function and cell fate. Extensive research on the structure and biological complexity of ECM has shown that three types of critical information from the ECM have influence on cellular behaviour: (1) biophysical properties (elasticity, stiffness), (2) biochemical properties (bioactive peptide epitopes of ECM molecules), and (3) nanoarchitecture (nanofibrillar structure, porosity) of ECM. Recent efforts have therefore focused on the construction of ECM mimetic materials to modulate tissue specific cell functions. Advances in biomaterial platforms include artificial ECM mimics of peptide conjugated synthetic polymer hydrogels presenting bioactive ligands produced with covalent chemistry. These materials have already found application in tissue engineering, however, these biomaterial platforms represent oversimplified mimics of cellular microenvironment and lack the complexity and multifunctional aspects of native ECM. In this work, we developed a novel polyethylene glycol (PEG)-peptide nanofiber composite hydrogel system with independently tunable biochemical, mechanical and physical cues that does not require any chemical modification of polymer backbone to create synthetic ECM analogues. This approach allows noninteracting modification of multifactorial niche properties (i.e. bioactive ligands, stiffness, porosity), since no covalent conjugation method was used to modify PEG monomers for the incorporation of bioactivity and porosity. Combining the self-assembled peptide nanofibers with crosslinked polymer network simply by facile mixing followed by photo-polymerization resulted in the formation of porous hydrogel systems. Resulting porous network can be functionalized with desired bioactive signalling epitopes by simply altering the amino acid sequence of peptide amphiphile molecules. In addition, the mechanical properties of the composite system can be precisely controlled by changing the PEG concentration. Ultimately, multifunctional PEG-peptide composite scaffolds reported in this work, can fill a critical gap in the available biomaterials as versatile synthetic mimics of ECM with independently tunable properties. Such a system could provide a useful tool allowing the investigation of how complex niche cues interplay to influence cellular behaviour and tissue formation both in 2D and 3D platforms.
Open Access
Heparin mimetic peptide nanofiber gel promotes regeneration of full thickness burn injury
(Elsevier Ltd, 2017) Yergoz, F.; Hastar, N.; Cimenci, C. E.; Ozkan, A. D.; Güler, Mustafa O.; Tekinay, A. B.; Tekinay, T.; Güler, Mustafa O.
Burn injuries are one of the most common types of trauma worldwide, and their unique physiology requires the development of specialized therapeutic materials for their treatment. Here, we report the use of synthetic, functional and biodegradable peptide nanofiber gels for the improved healing of burn wounds to alleviate the progressive loss of tissue function at the post-burn wound site. These bioactive nanofiber gels form scaffolds that recapitulate the structure and function of the native extracellular matrix through signaling peptide epitopes, which can trigger angiogenesis through their affinity to basic growth factors. In this study, the angiogenesis-promoting properties of the bioactive scaffolds were utilized for the treatment of a thermal burn model. Following the excision of necrotic tissue, bioactive gels and control solutions were applied topically onto the wound area. The wound healing process was evaluated at 7, 14 and 21 days following injury through histological observations, immunostaining and marker RNA/protein analysis. Bioactive peptide nanofiber-treated burn wounds formed well-organized and collagen-rich granulation tissue layers, produced a greater density of newly formed blood vessels, and exhibited increased re-epithelialization and skin appendage development with minimal crust formation, while non-bioactive peptide nanofibers and the commercial wound dressing 3M™ Tegaderm™ did not exhibit significant efficiency over sucrose controls. Overall, the heparin-mimetic peptide nanofiber gels increased the rate of repair of burn injuries and can be used as an effective means of facilitating wound healing.
Open Access
In situ synthesis of biomolecule encapsulated gold-cross-linked poly(ethylene glycol) nanocomposite as biosensing platform: A model study
(Elsevier BV, 2010) Odaci, D.; Kahveci, M.U.; Sahkulubey, E.L.; Ozdemir, C.; Uyar, Tamer; Timur, S.; Yagci Y.
In situ synthesis of poly(ethylene glycol) (PEG) hydrogels containing gold nanoparticles(AuNPs) and glucose oxidase (GOx) enzyme by photo-induced electron transfer process was reported here and applied in electrochemical glucose biosensing as the model system. Newly designed bionanocomposite matrix by simple one-step fabrication offered a good contact between the active site of the enzyme and AuNPs inside the network that caused the promotion in the electron transfer properties that was evidenced by cyclic voltammetryas well as higher amperometric biosensing responses in comparing with response signals obtained from the matrix without AuNPs. As well as some parameters important in the optimization studies such as optimum pH, enzyme loading and AuNP amount, the analytical characteristics of the biosensor (AuNP/GOx) were examined by the monitoring of chronoamperometric response due to the oxygen consumption through the enzymatic reaction at − 0.7 V under optimized conditions at sodium acetate buffer (50 mM, pH 4.0) and the linear graph was obtained in the range of 0.1–1.0 mM glucose. The detection limit (LOD) of the biosensor was calculated as 0.06 mM by using the signal to noise ratio of 3. Moreover, the presence of AuNPs was visualized by TEM. Finally, the biosensor was applied for glucose analysis for some beverages and obtained data were compared with HPLC as the reference method to test the possible matrix effect due to the nature of the samples.
Open Access
Laminin mimetic peptide nanofibers regenerate acute muscle defect
(Acta Materialia Inc, 2017) Cimenci, C. E.; Uzunalli, G.; Uysal, O.; Yergoz, F.; Umay, E. K.; Güler, Mustafa O.; Tekinay, A. B.
Skeletal muscle cells are terminally differentiated and require the activation of muscle progenitor (satellite) cells for their regeneration. There is a clinical need for faster and more efficient treatment methods for acute muscle injuries, and the stimulation of satellite cell proliferation is promising in this context. In this study, we designed and synthesized a laminin-mimetic bioactive peptide (LM/E-PA) system that is capable of accelerating satellite cell activation by emulating the structure and function of laminin, a major protein of the basal membrane of the skeletal muscle. The LM/E-PA nanofibers enhance myogenic differentiation in vitro and the clinical relevance of the laminin-mimetic bioactive scaffold system was demonstrated further by assessing its effect on the regeneration of acute muscle injury in a rat model. Laminin mimetic peptide nanofibers significantly promoted satellite cell activation in skeletal muscle and accelerated myofibrillar regeneration following acute muscle injury. In addition, the LM/E-PA scaffold treatment significantly reduced the time required for the structural and functional repair of skeletal muscle. This study represents one of the first examples of molecular- and tissue-level regeneration of skeletal muscle facilitated by bioactive peptide nanofibers following acute muscle injury. Significance Statement Sports, heavy lifting and other strength-intensive tasks are ubiquitous in modern life and likely to cause acute skeletal muscle injury. Speeding up regeneration of skeletal muscle injuries would not only shorten the duration of recovery for the patient, but also support the general health and functionality of the repaired muscle tissue. In this work, we designed and synthesized a laminin-mimetic nanosystem to enhance muscle regeneration. We tested its activity in a rat tibialis anterior muscle by injecting the bioactive nanosystem. The evaluation of the regeneration and differentiation capacity of skeletal muscle suggested that the laminin-mimetic nanosystem enhances skeletal muscle regeneration and provides a suitable platform that is highly promising for the regeneration of acute muscle injuries. This work demonstrates for the first time that laminin-mimetic self-assembled peptide nanosystems facilitate myogenic differentiation in vivo without the need for additional treatment.
Open Access
Mechanically controlled liesegang pattern formation in stretchable polyacrylamide gels for elastic deformation tracking
(2019-07) Morsali, Mohammad
Pattern formation in nature has been intellectually appealing for many scientists since antiquity. Simultaneous diffusion and reaction of chemicals in gel media may lead to precipitation and complex pattern formation through self-assembly. Periodic precipitations patterns, also known as Liesegang patterns (LP), are one of the stimulating examples of such self-assembling reaction-diffusion systems. So far, it was shown that LP’s periodic band structure and their unique geometry can be controlled by controlling the reaction parameters (e.g. concentration of the reactants) and affecting the reaction medium (e.g. external electrical field). However, so far, the research on LPs have been concentrated mostly around how these patterns are forming, to retrieve information to build a universal mathematical model for them. Although there are studies showing the effect of external fields on the development of these patterns, to the best of our knowledge, so far, there is no example of these systems, used to retrieve information about the changes in the environment as they form. Here, we first show the formation of Liesegang rings by a diffusion-precipitation reaction in a stretchable hydrogel. Then, we present how to use these patterns to ‘read’ the duration, the extent, and the direction of gel deformation. Also, we describe deviations from LP behavior for the patterns (spacing that can be mathematically defined by a geometrical series) formed after the unloading. We believe this first display of such an ‘environmental sensing’ to be a starting point for more investigations on many aesthetically appealing and mathematically challenging self-assembled systems, which have been studied for decades.
Open Access
One-dimensional peptide nanostructure templated growth of iron phosphate nanostructures for lithium-ion battery cathodes
(American Chemical Society, 2016-06) Susapto, H. H.; Kudu, O. U.; Garifullin, R.; Yllmaz, E.; Güler, Mustafa O.
Template-directed synthesis of nanomaterials can provide benefits such as small crystalline size, high surface area, large surface-to-volume ratio, and structural stability. These properties are important for shorter distance in ion/electron movement and better electrode surface/electrolyte contact for energy storage applications. Here nanostructured FePO4 cathode materials were synthesized by using peptide nanostructures as a template inspired by biomineralization process. The amorphous, high surface area FePO4 nanostructures were utilized as a cathode for lithium-ion batteries. Discharge capacity of 155 mAh/g was achieved at C/20 current rate. The superior properties of biotemplated and nanostructured amorphous FePO4 are shown compared to template-free crystalline FePO4.
Open Access
Peptide nanostructure templated growth of iron phosphate nanostrustures for energy storage applications
(2015-12) Susapto, Hepi Hari
The use of primary cells has been replaced with rechargeable batteries due to environmental concerns. Li-ion batteries are examples of the rechargeable batteries that have replaced other types of rechargeable batteries from market due to high capacity, high electrochemical potential, superior energy density, durability, as well as the flexibility in design. Compared to other cathode materials used in Li-ion batteries, the iron oxide (FePO4) is less toxic, environmentally friendly, and less expensive. Inorganic materials can be fabricated by template-directed mineralization to enable control over size and morphology. One-Dimensional (1-D) nanostructures can be used for template directed mineralization method. The nanostructures are particularly interesting as electrode materials due to their high surface area, large surface-to-volume ratio, and favorable structural stability. They provide fast ion/electron transfer by sufficient contact between the active materials and electrolyte. In this thesis, 1-D nanostructures of FePO4 materials with high surface area were synthesized to enhance the efficiency of Li-ion batteries. The synthesis of iron phosphate nanostructures was performed by using peptide amphiphile nanostructures. Iron (III) chloride (FeCl3) was used to trigger the self-assembly of the peptide amphiphile molecules forming nanostructures, which can nucleate FePO4 formation. The electrochemical performance of these nanostructures for Li-ion battery was analyzed. In conclusion, the template directed electrode materials revealed fast ion/electron transfer and sufficient contact between materials and electrolyte. They also exhibited enhanced flexibility leading to higher capacity than the electrode material synthesized without the template.
Open Access
Three-Dimensional Laminin Mimetic Peptide Nanofiber Gels for In Vitro Neural Differentiation
(Wiley-VCH Verlag, 2017) Gunay, Gokhan; Sever, Melike; Tekinay, Ayse B.; Güler, Mustafa O.
The extracellular matrix (ECM) provides biochemical signals and structural support for cells, and its functional imitation is a fundamental aspect of biomaterial design for regenerative medicine applications. The stimulation of neural differentiation by a laminin protein-derived epitope in two-dimensional (2D) and three-dimensional (3D) environments is investigated. The 3D gel system is found to be superior to its 2D counterpart for the induction of neural differentiation, even in the absence of a crucial biological inducer in nerve growth factor (NGF). In addition, cells cultured in 3D gels exhibits a spherical morphology that is consistent with their form under in vivo conditions. Overall, the present study underlines the impact of bioactivity, dimension, and NGF addition, as well as the cooperative effects thereof, on the neural differentiation of PC-12 cells. These results underline the significance of 3D culture systems in the development of scaffolds that closely replicate in vivo environments for the formation of cellular organoid models in vitro. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim