Digital image analysis for biothreat detection via rapid centrifugal microfluidic orthogonal flow immunocapture

We report clear proof-of-principle for centrifugally-driven, multiplexed, paper-based orthogonal flow sandwich-style immunocapture (cOFI) and colorimetric detection of Zaire Ebola virus-like particles. Capture antibodies are immobilized onto nanoporous nitrocellulose membranes that are then laminated into polymeric microfluidic discs to yield ready-to-use analytical devices. Fluid flow is controlled solely by rotational speed, obviating the need for complex pneumatic pumping systems, and providing more precise flow control than with the capillary-driven flow used in traditional lateral flow immunoassays (LFIs). Samples containing the antigen of interest and gold nanoparticle-labeled detection antibodies are pumped centrifugally through the embedded, prefunctionalized membrane where they are subsequently captured to generate a positive, colorimetric signal. When compared to the equivalent LFI counterparts, this cOFI approach generated immunochromatographic colorimetric responses that are objectively darker (saturation), more intense (grayscale), and less variable regarding total area of the color response. We also describe an image analysis approach that enables access to rich color data and area statistics without the need for a commercial 'strip reader' or custom-written image analysis algorithms. Instead, our analytical method exploits inexpensive equipment (e.g., smart phone, flatbed scanner, etc.) and freely available software (Fiji distribution of ImageJ) to permit characterization of immunochromatographic responses that includes multiple color metrics, offering insights beyond typical grayscale analysis. The findings reported here stand as clear proof-of-principle for the feasibility of disc-based, centrifugally driven orthogonal flow through a membrane with immunocapture (cOFI) and colorimetric readout of a sandwich-type immunoassay in less than 15 minutes. Once fully developed, this cOFI platform could render a faster, more accurate diagnosis, while processing multiple samples simul-taneously.

Characterization of a Centrifugal Microfluidic Orthogonal Flow Platform

To bring to bear the power of centrifugal microfluidics on vertical flow immunoassays, control of flow orthogonally through nanoporous membranes is essential. The on-disc approach described here leverages the rapid print-cut-laminate (PCL) disc fabrication and prototyping method to create a permanent seal between disc materials and embedded nanoporous membranes. Rotational forces drive fluid flow, replacing capillary action, and complex pneumatic pumping systems. Adjacent microfluidic features form a flow path that directs fluid orthogonally (vertically) through these embedded membranes during assay execution. This method for membrane incorporation circumvents the need for solvents (e.g., acetone) to create the membrane-disc bond and sidesteps issues related to undesirable bypass flow. In other recently published work, we described an orthogonal flow (OF) platform that exploited embedded membranes for automation of enzyme-linked immunosorbent assays (ELISAs). Here, we more fully characterize flow patterns and cellulosic membrane behavior within the centrifugal orthogonal flow (cOF) format. Specifically, high-speed videography studies demonstrate that sample volume, membrane pore size, and ionic composition of the sample matrix significantly impact membrane behavior, and consequently fluid drainage profiles, especially when cellulosic membranes are used. Finally, prototype discs are used to demonstrate proof-of-principle for sandwich-type antigen capture and immunodetection within the cOF system.

Clinical and neurohormonal correlates of circulating granulocyte-macrophage colony-stimulating factor in severe heart failure secondary to ischemic or idiopathic dilated cardiomyopathy

In this report, we showed for the first time that granulocyte-macrophage colony-stimulating factor plasma levels are elevated in patients with severe heart failure, and these levels are correlated well with neurohormonal activation and hemodynamic deterioration characterizing this syndrome.

Serum profiles of granulocyte-macrophage colony-stimulating factor and C-C chemokines in hypertensive patients with or without significant hyperlipidemia

The present study investigates the differences in serum activity of granulocyte-macrophage colony-stimulating factor, macrophage chemoattractant protein-1, and macrophage inflammatory protein-1alpha between hypertensive patients with and without significant hyperlipidemia before receiving any medical treatment. The serum activity of the studied inflammatory factors is more elevated in hypertensive patients with significant hyperlipidemia and may be associated with atherosclerotic inflammatory process induced by the coexistence of 2 major cardiovascular risk factors.

Tumor necrosis factor-alpha serum activity during treatment of acute decompensation of cachectic and non-cachectic patients with advanced congestive heart failure

Tumor necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine that produces left ventricular dysfunction and a negative inotropic effect in cardiac tissue when overexpressed in human subjects. Previous studies have shown that levels of circulating TNF-alpha are elevated in patients with advanced congestive heart failure (CHF) and especially in those with cardiac cachexia. To clarify the potential role of TNF-alpha in the unstable state of decompensated advanced CHF, we investigated the TNF-alpha serum activity in 25 cachectic and 22 non-cachectic CHF patients (New York Heart Association, NYHA functional classes III or IV), who were treated with intravenous diuretics and positive inotropic agents for acute decompensation of the disease, during a 5-day hospitalization period, as well as in 15 age-matched healthy control subjects. Cachectic CHF patients needed higher dosages of inotropic agents than non-cachectic patients and the determination of TNF-alpha serum concentrations in this patient group showed high levels of TNF-alpha at hospital admission (18.3 +/- 3.2 pg/ml) and a transient increase in circulating TNF-alpha during the treatment period with the highest levels on the 2nd day of hospitalization (32.5 +/- 7.1 pg/ml). The TNF-alpha serum levels were low in non-cachectic CHF patients and healthy controls on the 1st day (4.0 +/- 0.9 and 3.7 +/- 0.6 pg/ml, respectively) and did not change substantially during the course of the study. The present results show that TNF-alpha serum activity is transiently increased during the treatment of decompensated cachectic CHF patients only and may be related to the clinical instability and the consequent therapeutic interventions in this category of CHF patients.