Serdar Sezer

Thiochalcone substituted phthalocyanines for dye-sensitized solar cells: Relation of optical and electrochemical properties for cell performance

Abstract The new peripherally tetra-substituted metallophthalocyanines (MPcs, M=Zn, Co, Ni) bearing the chalcone, (E)-3-(4-hydroxyphenyl)-1-(thiophen-2-yl)prop-2-en-1-one, for dye-sensitized solar cells (DSSCs) were synthesized. FT-IR, 1H NMR, 13C NMR, and UV–Vis spectroscopy techniques were utilized for characterization of all the MPcs. Electrochemical, optical and photovoltaic properties of all the MPcs as sensitizers were examined. Electrochemical studies reveal that while the ZnPc (4) and NiPc (6) give only Pc ring-based redox reactions, the CoPc (5) shows redox reactions based on both the central metal and the ring due to the metal 3d orbitals lying between the Pc HOMO and LUMO. The DSSC based on 5 gave the lowest power conversion efficiency (0.51%), perhaps due to the presence of a redox active central metal ion in the core of the complex, which results in a decrease electron transfer in the device. However, cells based on the other complexes including redox inactive central metal ions, which cannot reduce electron transfer, showed reasonable power conversion efficiencies of 1.27% and 1.11% for 4 and 6, respectively. The slight difference between the efficiencies can be attributed to higher molar extinction coefficient and narrower band gap of 4 than 6, which ensure a higher photocurrent and broader light absorption in the visible region.

Combination of gelatin and tranexamic acid offers improved haemostasis and safe use on internal hemorrhage control

Effective hemorrhage control with materials developed by emerging technologies is important in preventing massive bleeding in hospitals, accident sites and battlefields. Various materials have been developed for the treatment of hemorrhage. Gelatin is one, which is commonly used in combination with thrombin. It is generally used in internal bleeding cases owing to its safety, and superior biocompatibility and biodegradability. On the other hand, thrombin the main component that provides rapid haemostasis has drawbacks such as serious disease transmission from donors and high cost. Chitosan is another haemostatic material component with low cost and superior efficiency. However, chitosan-based haemostatic materials are not recommended for internal use. In this paper, we examine the use of a combination of gelatin and tranexamic acid microparticles in internal bleeding control, on the basis of comparative studies both in in vitro and in in vivo conditions. This composite haemostatic material provided rapid haemostasis and biocompatibility, and provided a safe use in internal applications.

Zero valent zinc nanoparticles promote neuroglial cell proliferation: A biodegradable and conductive filler candidate for nerve regeneration

Regeneration of nerve, which has limited ability to undergo self-healing, is one of the most challenging areas in the field of tissue engineering. Regarding materials used in neuroregeneration, there is a recent trend toward electrically conductive materials. It has been emphasized that the capacity of conductive materials to regenerate such tissue having limited self-healing ability improves their clinical utility. However, there have been concerns about the safety of materials or fillers used for conductance due to their lack of degradability. Here, we attempt to use poly(Ɛ-caprolactone) (PCL) matrix consisting of varying proportions of zero valent zinc nanoparticles (Zn NPs) via electrospinning. These conductive, biodegradable, and bioactive materials efficiently promoted neuroglial cell proliferation depending on the amount of Zn NPs present in the PCL matrix. Chemical characterizations indicated that the incorporated Zn NPs do not interact with the PCL matrix chemically and that the Zn NPs improved the tensile properties of the PCL matrix. All composites exhibited linear conductivity under in vitro conditions. In vitro cell culture studies were performed to determine the cytotoxicity and proliferative efficiency of materials containing different proportions of Zn NPs. The results were obtained to explore new conductive fillers that can promote tissue regeneration.

Polyacrylamide-based semi-interpenetrating networks for entrapment of laccase and their use in azo dye decolorization.

In this study, laccase from Trametes versicolor was immobilized in poly(acrylamide‐crotonic acid)/sodium alginate [P(AAm‐CrA)/alginate], poly(acrylamide‐crotonic acid)/K‐carrageenan [(P(AAm‐CrA)/K‐car)], poly(acrylamide‐citraconic acid)/sodium alginate (P(AAm‐CA)/alginate), and poly(acrylamide‐citraconic acid)/K‐carrageenan (P(AAm‐CA)/K‐car) semi‐interpenetrating network by entrapment method. Optimum pH and temperatures values were determined between 5.0–6.0 and 40–50 °C for free laccase (FL) and immobilized laccases, respectively. After 42 days of storage at 4 °C, FL and immobilized laccases retained their original activities in the range of 55%–73%. Percent decolorization of Acid Orange 52 by free enyzme and enyzmes immobilized in hydrogels was found between 63% and 39%. Percent decolorization of Acid Orange 52 in the presence of mediator by free enyzme was found 73% and enyzmes immobilized in hydrogels were found as 73%.

Cellulose-Based Hydrogels as Biomaterials

Hydrogels are three-dimensional hydrophilic network structures that vary greatly in swelling/shrinkage properties against minor changes such as light density, solvent composition, ionic strength, pH, and temperature. Cellulose-based hydrogels are derived from natural sources which are biodegradable and S. Sezer (*) · Ü. A. Sezer Faculty of Medicine, Department of Pharmacology Medicine, Medical Device and Dermocosmetic Research and Application Laboratory, Süleyman Demirel University, Isparta, Turkey YETEM, Innovative Technologies Research and Application Center, Suleyman Demirel University, Isparta, Turkey e-mail: serdarsezer@sdu.edu.tr İ. Şahin · K. Öztürk · V. Şanko · Z. Koçer Institute of Chemical Technology, TUBITAK Marmara Research Center, Gebze, Kocaeli, Turkey # Springer International Publishing AG, part of Springer Nature 2018 Md. I. H. Mondal (ed.), Cellulose-Based Superabsorbent Hydrogels, Polymers and Polymeric Composites: A Reference Series, https://doi.org/10.1007/978-3-319-76573-0_40-1 1 low-immunologic. These hydrogels are produced in four different ways: those obtained directly from native cellulose (including bacterial cellulose), those derived from cellulose derivatives (methyl cellulose, carboxymethyl cellulose, hydroxy methyl cellulose, etc.), those obtained with other polymers as a composite, and finally those obtained from cellulose-inorganic hybrids. Cellulose hydrogels and its derivatives have many desirable properties such as high water retention capacity, high crystallinity, fine fiber network, easy formability, and high tensile strength. In addition, some cellulose derivatives exhibit intelligent behavior against physiological variables such as pH and ionic strength. Cellulosebased hydrogels have advantages such as better biocompatibility, less latent toxicity, and lower cost than the most synthetic polymer hydrogels. Because of these advantages, cellulose-based hydrogels are preferred to be used in industrial pharmaceutics and biomedical fields. This chapter will discuss applications of cellulose-based hydrogels in pharmaceutical industry and biomedical fields such as drug release systems, wound healing, and tissue engineering. In addition, future prospects on cellulose-based hydrogels will be addressed.

Carboxymethyl cellulose/oxidized regenerated cellulose hydrogels as adhesion barriers: comparative study with different molecular weights and substitution degrees

For hydrogel materials used in surgery to prevent post-operative adhesion formation, the ability to reduce adhesion formation effectively through ease of application is the most outstanding attribute for improving their clinical utility. In this study, hydrogel formulation with carboxymethyl cellulose (CMC) and water soluble sodium oxidized regenerated cellulose (ORC) powder was developed. The formulation was achieved with different molecular weights and degrees of substitution of the CMC to investigate the effects of these two variables on adhesion prevention. In vivo studies showed that hydrogel formulations with medium molecular weight and a higher degree of substitution gave the best anti-adhesion performance. Histological analyses indicated the materials did not damage the tissue at the surgery area. Promising results were obtained for the development of ORC containing hydrogel formulations for post-operative adhesion prevention applications.