Nanomaterials integrated with microfluidic paper-based analytical devices for enzyme-free glucose quantification.

In this study, nanomaterials capable of enzyme-free glucose quantification and colorimetric readout are integrated into a microfluidic paper-based analytical devices (µPADs). Gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) were utilized as a peroxidase-like nanozyme and a colorimetric probe to achieve glucose monitoring. In this developed device, glucose is oxidized by AuNPs to generate hydrogen peroxide (H2O2), which flows in the paper microchannels toward detection zones. H2O2 then etches the immobilized AgNPs to induce a color change. The intensity of color change is easily monitored using a smartphone application. Following method optimization, we obtained a linear range from 0.50 to 10.0 mmol L-1 (R2 = 0.9921) and a detection limit (LOD) of 340.0 µmol L-1. This falls in the clinically relevant range for glucose monitoring and diabetes diagnosis in humans. In addition, the total analysis time is just 20 min, which is significantly less than the same experiment performed in the solution phase. Also, our method is markedly selective; other substrates do not interfere. The recovery test in human control samples was in the range of 98.47-102.34% and the highest relative standard deviation (RSD) was 3.58%. The enzyme-free approach for glucose sensing is highly desirable for diabetes diagnosis as it replaces the more expensive enzyme with cheaper nanomaterials. Furthermore, since nanomaterials are more environmentally stable compared to enzymes, it has the potential for widespread deployment as point-of-care diagnostics (POC) in resource-limited settings.

Endocardial irregularities of the left atrial roof as seen on coronary CT angiography.

OBJECTIVE: To describe and characterize morphological characteristics of endocardial irregularities in the roof of the left atrium as seen on coronary CT angiography. METHODS: We retrospectively evaluated the left atrium in 50 consecutive coronary CT patients with multiplanar reformatting, volume rendering, and virtual endoscopy. RESULTS: Twenty-one of the 50 patients had an endocardial irregularity at the roof of the left atrium. The most common finding (n = 14) was a smooth diverticulum, arising near the venoatrial junction of the right superior pulmonary vein. CONCLUSION: Endocardial irregularities of the left atrium can be identified on coronary CT and may be more common than previously considered. The findings probably represent remnants of the cardinal venous system during embryological development. Further work should focus on the true prevalence and potential clinical significance.

Lower extremity peripheral vein bypass graft wall thickness changes demonstrated at 1 and 6 months after surgery with ultra-high spatial resolution black blood inner volume three-dimensional fast spin echo magnetic resonance imaging.

OBJECTIVE: To demonstrate lower extremity peripheral vein bypass graft wall thickness changes over time in a patient using very high spatial resolution cardiac gated, black blood inner volume three-dimensional (3D) fast spin echo (FSE) magnetic resonance imaging (MRI). CASE REPORT: A 52-year-old diabetic man with a history of hyperlipidemia underwent uncomplicated bypass grafting for an asymptomatic 5.2 cm popliteal artery aneurysm using reversed great saphenous vein. A segment of the bypass graft was studied at 1 and 6 months after surgery with cardiac gated inner volume 3D-FSE imaging with non-interpolated 0.195 mm(3) voxel volumes (0.3125 x 0.3125 x 2 mm). T1- and T2-weighted images were acquired in 10 min per contrast weighting. Graft imaging at one month after implantation illustrates expansion of the outer wall of the graft that partially resolves 5 months later. CONCLUSION: In this patient, expansion of the lower extremity peripheral bypass graft wall can be characterized in clinical scan times with a 3D-FSE MRI protocol using highly selective inner volume excitation followed by non-selective refocusing pulses. The resulting 3D images can potentially be used to study the biology of the vessel wall.