Browsing by Subject "Functionalizations"
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Item 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, MehmetMictoroids, 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.Item Open Access Tuning electronic properties of monolayer hexagonal boron phosphide with group III-IV-V dopants(American Chemical Society, 2017-02) Onat, B.; Hallioglu, L.; Ipek, S.; Durgun, EnginAn extensive study on doping of two-dimensional (2D) hexagonal boron phosphide (h-BP) which is a direct band gap semiconductor was performed by using ab initio methods based on spin-polarized density functional theory. The interaction of group III-IV-V elements with h-BP is explored, considering both adsorption and substitution cases, and the resulting structural and electronic properties are examined. The variation of adsorption (substitution) energies and band gap values are systematically analyzed and trends are identified. Upon adsorption, the most of the elements bound on top of P atom forming dumbbell geometry which generates characteristic spin-polarized impurity states. The substitution of B or P by group III-IV-V elements can produce extra electrons/holes which lead to n-type and p-type doping for adequate cases. Additionally, doping can further generate impurity resonant states. Functionalization of h-BP with adatoms can tune the electronic structure and would be useful for nanoelectronic applications in low-dimensions.