Browsing by Subject "Photopolymerization"
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Item Open Access Fabrication of polymer micro needles for transdermal drug delivery system using DLP based projection stereo-lithography(Elsevier, 2016) Ali, Z.; Türeyen, E. Buğra; Karpat, Yiğit; Çakmakcı, MelihFabrication of micro needles, which reduce pain during insertion and lessen tissue injury, has recently attracted great interest. Different manufacturing systems have been utilized for the advancement of micro needles such as two-photon photo polymerization, bulk lithography, droplet-borne air blowing and injection molding [1]. This paper proposes a micro fabrication process for polymer micro needles, using DLP based projection-based stereo lithography that is capable of fabricating micro-needles using biocompatible polymers. The fabrication in the experimental setup is performed with continuous movement of the platform in the vertical direction hence good surface quality is obtained. The influence of polymerization time, light intensity of DLP projector and chemical composition of the resins on the production speed and the geometrical accuracy of the micro needles have been studied. The length and the tip diameter of the micro needle are shown to be controlled through these factors. The length and tip diameter of the fabricated micro needles were observed using SEM and optical microscope and measured to be around 520 μm and 40 μm, respectively. The results indicate that polymer micro needles with appropriate geometry can be fabricated using this technique. © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license.Item 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.Item Open Access Simultaneous photoinduced electron transfer and photoinduced CuAAC processes for antibacterial thermosets(Elsevier, 2017) Oz, E.; Uyar, T.; Esen, H.; Tasdelen, M. A.A combination of simultaneous photoinduced electron transfer and photoinduced CuAAC processes enables the in-situ preparation of antibacterial thermosets containing silver nanoparticles (AgNPs) in one-pot. Upon photolysis of photoinitator, the generated radicals not only reduce Cu(II) into Cu(I) activator to catalyst the CuAAC click reaction, but also simultaneously generate AgNPs from AgNO3 through electron transfer reaction. Due to their reduction potentials difference, the polymer matrix is formed before the formation of AgNPs, assisting to eliminate the agglomeration of them. The thermoset structures are confirmed by FT-IR and solubility tests, whereas the presence of AgNPs is proven by transmission electron microscopy with energy dispersive X-ray system analyzer. The samples containing 5 and 10% AgNPs exhibited strong inhibition zones, where all kinds of bacteria (gram-positive (Staphylococcus Aureus) and gram-negative (Escherichia Coli)) were killed in the surrounding of the film samples.