Diamond, because of its electrical and chemical properties, may be a suitable material for integrated sensing and signal processing. But methods to control chemical or biological modifications on diamond surfaces have not been established. Here, we show that nanocrystalline diamond thin-films covalently modified with DNA oligonucleotides provide an extremely stable, highly selective platform in subsequent surface hybridization processes. We used a photochemical modification scheme to chemically modify clean, H-terminated nanocrystalline diamond surfaces grown on silicon substrates, producing a homogeneous layer of amine groups that serve as sites for DNA attachment. After linking DNA to the amine groups, hybridization reactions with fluorescently tagged complementary and non-complementary oligonucleotides showed no detectable non-specific adsorption, with extremely good selectivity between matched and mismatched sequences. Comparison of DNA-modified ultra-nanocrystalline diamond films with other commonly used surfaces for biological modification, such as gold, silicon, glass and glassy carbon, showed that diamond is unique in its ability to achieve very high stability and sensitivity while also being compatible with microelectronics processing technologies. These results suggest that diamond thin-films may be a nearly ideal substrate for integration of microelectronics with biological modification and sensing.

Heterogeneous nucleation of water plays an important role in a wide range of natural and industrial processes. Though heterogeneous nucleation of water is ubiquitous and an everyday experience, spatial control of this important phenomenon is extremely difficult. Here we show for the first time that spatial control in the heterogeneous nucleation of water can be achieved by manipulating the local nucleation energy barrier and nucleation rate via the modification of the local intrinsic wettability of a surface. Such ability to control water nucleation could address the condensation-related limitations of superhydrophobic surfaces and has implications for efficiency enhancements in energy and desalination systems.

Both VMAT and HT plans can be delivered accurately based on their own QA standards. Overall, VMAT was able to provide approximately a 40% reduction in treatment time while maintaining comparable plan quality to that of HT.

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We have investigated the frequency-dependent interfacial electrical properties of nanocrystalline diamond films that were covalently linked to DNA oligonucleotides and how these properties are changed upon exposure to complementary and noncomplementary DNA oligonucleotides. Frequency-dependent electrical measurements at the open-circuit potential show significant changes in impedance at frequencies of >10(4) Hz when DNA-modified diamond films are exposed to complementary DNA, with only minimal changes when exposed to noncomplementary DNA molecules. Measurements as a function of potential show that at 10(5) Hz, the impedance is dominated by the space-charge region of the diamond film. DNA molecules hybridizing at the interface induce a field effect in the diamond space-charge layer, altering the impedance of the diamond film. By identifying a range of impedances where the impedance is dominated by the diamond space-charge layer, we show that it possible to directly observe DNA hybridization, in real time and without additional labels, via simple measurement of the interfacial impedance.

PURPOSE To develop a 4D-MRI technique to characterize the average respiratory tumor motion for abdominal radiotherapy planning. METHODS A continuous spoiled gradient echo sequence was implemented with 3D radial trajectory and 1D self-gating for respiratory motion detection. Data were retrospectively sorted into different respiratory phases based on their temporal locations within a respiratory cycle, and each phase was reconstructed via a self-calibrating CG-SENSE program. Motion phantom, healthy volunteer and patient studies were performed to validate the respiratory motion detected by the proposed method against that from a 2D real-time protocol. RESULTS The proposed method successfully visualized the respiratory motion in phantom and human subjects. 4D-MRI and real-time 2D-MRI yielded comparable superior-inferior (SI) motion amplitudes (intra-class correlation = 0.935) with up-to 1 pixel mean absolute differences in SI displacements over 10 phases and high cross-correlation between phase-resolved displacements (phantom: 0.985; human: 0.937–0.985). Comparable anterior-posterior and left-right displacements of the tumor or gold fiducial between 4D and real-time 2D-MRI were also observed in the two patients, and the hysteresis effect was shown in their 3D trajectories. CONCLUSION We demonstrated the feasibility of the proposed 4D-MRI technique to characterize abdominal respiratory motion, which may provide valuable information for radiotherapy planning.

We demonstrate the electrically addressable biomolecular functionalization of single-walled carbon nanotube electrodes and vertically aligned carbon nanofiber electrodes. The method uses an electrochemical reaction in which nitro groups on specific nanostructures are reduced to amino groups and then used to covalently link DNA to only these nanostructures. We demonstrate fabrication of a four-element array of distinct DNA oligonucleotides on carbon nanotube electrodes and the addressable functionalization of submicron bundles of <100 nm diameter vertically aligned carbon nanofibers. DNA hybridization shows that the DNA-modified nanoscale structures have excellent biological selectivity.

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