Browsing by Subject "Biosensing platforms"

Now showing 1 - 2 of 2

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
Real-time and selective detection of single nucleotide DNA mutations using surface engineered microtoroids
(American Chemical Society, 2015) Toren, P.; Ozgur E.; Bayındır, Mehmet
Mictoroids, as optical biosensors, can provide beneficial biosensing platforms to understand DNA alterations. These alterations could have significant clinical importance, such as the case of Pseudomonas aeruginosa, which is a commonly found pathogen in Cystic Fibrosis (CF) patients-causing poor prognosis by undergoing mutations during disease steps, gaining virulence and drug resistance. To provide a preliminary diagnosis platform for early-stage bacterial mutations, biosensing with a selective microtoroid surface was suggested. For this purpose, microtoroids with high quality factors were fabricated. The microtoroid surfaces were coated with (3-aminopropyl) triethoxysilane (APTES)/trimethylmethoxysilane (TMMS) mixed silane solution followed by EDC/NHS chemistry for covalent conjugation of DNA probes. Ethanolamine capping was applied to avoid unspecific interactions. The confocal studies confirmed homogeneous functionalization of the microtoroid surface. The DNA hybridization was demonstrated to be affected from the probe length. The optical biosensors showed a significant response (∼22 pm) to the complementary strand of the mutated type P. aeruginosa DNA, while showing substantially low and late response (∼5 pm) to the point mismatch strand. The limit of detection (LOD) for the complementary strand was calculated as 2.32 nM. No significant response was obtained for the noncomplementary strand. The results showed the microtoroids possessed selective surfaces in terms of distinguishing DNA alterations.