Charge State Dynamics and Optically Detected Electron Spin Resonance Contrast of Shallow Nitrogen-Vacancy Centers in Diamond

Nitrogen-vacancy (NV) centers in diamond can be used for nanoscale sensing with atomic resolution and sensitivity; however, it has been observed that their properties degrade as they approach the diamond surface. Here we report that in addition to degraded spin coherence, NV centers within nanometers of the surface can also exhibit decreased fluorescence contrast for optically detected electron spin resonance (OD-ESR). We demonstrate that this decreased OD-ESR contrast arises from charge state dynamics of the NV center, and that it is strongly surface-dependent, indicating that surface engineering will be critical for nanoscale sensing applications based on color centers in diamond

Diamond Surface Functionalization via Visible Light-Driven C-H Activation for Nanoscale Quantum Sensing

Nitrogen-vacancy centers in diamond are a promising platform for nanoscale nuclear magnetic resonance sensing. Despite significant progress towards using NV centers to detect and localize nuclear spins down to the single spin level, NV-based spectroscopy of individual, intact, arbitrary target molecules remains elusive. NV molecular sensing requires that target molecules are immobilized within a few nanometers of NV centers with long spin coherence time. The inert nature of diamond typically requires harsh functionalization techniques such as thermal annealing or plasma processing, limiting the scope of functional groups that can be attached to the surface. Solution-phase chemical methods can be more readily generalized to install diverse functional groups, but they have not been widely explored for single-crystal diamond surfaces. Moreover, realizing shallow NV centers with long spin coherence times requires highly ordered single-crystal surfaces, and solution-phase functionalization has not yet been shown to be compatible with such demanding conditions. In this work, we report a versatile strategy to directly functionalize C-H bonds on single-crystal diamond surfaces under ambient conditions using visible light. This functionalization method is compatible with charge stable NV centers within 10 nm of the surface with spin coherence times comparable to the state of the art. As a proof of principle, we use shallow ensembles of NV centers to detect nuclear spins from functional groups attached to the surface. Our approach to surface functionalization based on visible light-driven C-H bond activation opens the door to deploying NV centers as a broad tool for chemical sensing and single-molecule spectroscopy

Serum ibuprofen levels of extremely preterm infants treated prophylactically with oral ibuprofen to prevent patent ductus arteriosus

<p>The aim of this study was to explore the effects of early oral ibuprofen administration on the incidence of hemodynamically significant patent ductus arteriosus (hsPDA) and define the association between serum ibuprofen levels and ductal closure.</p><p>Preterm infants with a gestational age of <28 weeks and/or birth weight of <1,000 g were randomized either to the intervention (ibuprofen prophylaxis) or control group. The intervention group received oral ibuprofen 10 mg/kg within 12-24 h after birth followed by 5 mg/kg at 24 and 48 h. Serum ibuprofen levels after the treatment were analyzed in the intervention group, and the incidence of hsPDA and complication rates were compared between two groups.</p><p>Nineteen infants who received one course (three doses) of prophylactic ibuprofen in the intervention group and 17 infants in the control group who underwent an echocardiographic examination on the fourth day of life were analyzed. hsPDA was observed in five (26 %) infants in the intervention group and ten (58 %) infants in the control group (p = 0.09). In the intervention group two infants experienced gastrointestinal bleeding two infants had spontaneous intestinal perforation, and two infants developed acute kidney failure. Mean serum ibuprofen level was 28.7 +/- 16.9 mg/L in the intervention group, and there was no correlation between ibuprofen level obtained on the fourth day and ductal closure.</p><p>Oral ibuprofen prophylaxis reduces the rates of hsPDA even it is not statistically significant. The ductal closure rate did not correlate with serum ibuprofen levels. Due to high prevalence of adverse events observed, our data do not support the use of oral ibuprofen for prophylaxis of hsPDA.</p>