Fabrication of a Patterned Scaffold Using Soft Lithography Technique to be Used in Cell Growth Applications.

In recent years, within tissue engineering, cell growth on patterned surfaces have gained significant attention. Growing cells in patterns is important to manufacture polymeric tissues that can be used within the medical field. For this reason, the main focus of this study was to prepare patterned scaffolds using Titanium (Ti) and polyvinyl chloride (PVC) covered on microscope lamellas and examine their liability for cell growth. A polydimethylsiloxane stamp was initially prepared which was then used to transfer a predefined pattern onto PVC- and Ti-covered surfaces. Cell growth experiments were performed on the prepared materials by seeding L929 mouse fibroblasts. The growth of cells seeded on the surface of the scaffolds were spectroscopically followed using Neutral Red uptake assay. The results showed cell proliferation on both patterned surfaces, however, it was higher on Ti-covered samples. In addition, three different alkanethiols were tested for cell adhesion on patterned surfaces. A higher number of cell proliferation was observed with undecanethiol, which has a shorter alkane group among them. The morphological properties of the samples before and after cell-seeding were analyzed via scanning electron microscope and optical microscopy. Significant amount of cell proliferation was observed on all of the prepared samples.

Preparation and characterization of polymers based on PDMS and PEG-DMA as potential scaffold for cell growth.

This work describes a soft lithographic method for the generation of patterned both biopolymer and silver with each covered on microscope glass. Because of their biocompatible nature and permeability to gases the biopolymers are convenient for cell culture studies. The microscope glass was covered by polyethylene glycol dimethyl acrylate (PEG-DMA), as biopolymer and patterned by the UV light passing through the printed photomask for the preparation of the PDMS stamps. PDMS stamps were originally fabricated in this work for pattern transfer. Ag and polymer covered on the microscope glass were patterned by using these PDMS stamps. The patterned Ag, PDMS mold and PEG-DMA biopolymer were used as scaffolds and cell growth experiments have been performed on these materials. The degree of cell viability was measured by seeding them with L929 mouse fibroblasts and the number of the cells was measured by neutral red uptake assay. An increase in the number of cells on the material surfaces was observed. The pattern and the cell growth properties were followed by optic microscope. The results obtained from the cell growth was subjected to student's t-test.

Alginate/polyoxyethylene and alginate/gelatin hydrogels: preparation, characterization, and application in tissue engineering.

Hydrogels are attractive biomaterials for three-dimensional cell culture and tissue engineering applications. The preparation of hydrogels using alginate and gelatin provides cross-linked hydrophilic polymers that can swell but do not dissolve in water. In this work, we first reinforced pure alginate by using polyoxyethylene as a supporting material. In an alginate/PEO sample that contains 20 % polyoxyethylene, we obtained a stable hydrogel for cell culture experiments. We also prepared a stable alginate/gelatin hydrogel by cross-linking a periodate-oxidized alginate with another functional component such as gelatin. The hydrogels were found to have a high fluid uptake. In this work, preparation, characterization, swelling, and surface properties of these scaffold materials were described. Lyophilized scaffolds obtained from hydrogels were used for cell viability experiments, and the results were presented in detail.

Chitosan/alginate crosslinked hydrogels: preparation, characterization and application for cell growth purposes.

Chitosan hydrogels may be formed by various mechanisms. In this study, we aimed to form hybrid polymer networks of chitosan with alginate using a crosslinker which enabled the covalent binding of the two macromolecules. The structural and thermal characterization of these hydrogels was performed by using Fourier transform infrared (FTIR) and differential scanning calorimeter (DSC). The morphological analysis of the crosslinked material was investigated by scanning electron microscopy (SEM) and a scanning probe microscope with atomic force microscope (AFM) attachment. The swelling properties of these gels were analyzed in water and in phosphate buffered saline (PBS) solution. The presence of alginate in a chitosan/alginate hydrogel was shown to support the hydrogel stability. Compared to chitosan/alginate (1/2) hydrogel prepared with 1wt% DCC, the swelling of chitosan/alginate (1/2) hydrogels prepared with 3wt% DCC was limited. To measure the degree of cell proliferation, the hydrogels were seeded with L929 mouse fibroblasts and cell numbers measured by neutral red uptake assay. The cell attachment was also followed by (SEM) photography. It was observed that chitosan/alginate (1/2) hydrogels with 1wt% (DCC) provides a better environment for cell attachment and proliferation. This study presents functional hydrogel formation by crosslinked chitosan and alginate, a novel biomaterial which also supports cell growth.

Adsorption of methylene blue from aqueous solution on pyrolyzed petrified sediment.

The adsorption kinetics of methylene blue on pyrolyzed petrified sediment (PPS) has been performed using a batch-adsorption technique. The effects of various experimental parameters, such as initial dye concentration, contact time, and temperature were investigated. The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data. The best correlation coefficient was obtained using the pseudo first-order kinetic model, which shows that the adsorption of methylene blue followed the pseudo-first-order rate expression and the rate constants were evaluated. The Langmuir and Freundlich adsorption isotherm models were applied to describe the equilibrium isotherms and the isotherm constants were determined. It was found that the data fitted well to Langmuir and Freundlich models. The activation energy of adsorption was also evaluated for the adsorption of methylene blue onto pyrolyzed sediment. It was found about 8.5 kJ mol(-1). Thermodynamics parameters DeltaG(o), DeltaH(o), DeltaS(o) were calculated, indicating that this process can be spontaneous and endothermic. The adsorption enthalpy and entropy were found as 14-18.5 kJ mol(-1) and 52.8-67 J mol(-1) K(-1), respectively. The results obtained from the adsorption process using PPS as adsorbent was subjected to student's t-test.