Analyst Blog

Tracking the activity of viruses has never been so easy thanks to the latest development from Chao Han and Changhuei Yang, researchers at the California Institute of Technology, USA.  The duo has developed ePetri, a high performance imaging platform capable of monitoring the formation of viral plaques, an event that occurs when a virus infects a host cell. Unlike conventional plaque assays, ePetri provides high resolution, time-lapse imaging for precise monitoring of the dynamics of viral plaque formation and growth. In addition to enabling better analysis of viral behaviour, the capabilities of ePetri may also facilitate future applications in antiviral drug discovery. Learn more by accessing the link below. 

ePetri Instrument for Viral Plaque Analysis

Viral plaque analysis on a wide field-of-view, time-lapse, on-chip imaging platform 

Chao Han and Changhuei Yang 

DOI: 10.1039/C3AN02323K, Paper

Recent surveys from Allergy UK have shown that the rates of allergy are increasing throughout the world, affecting up to 30-35 % of people at some point during their lives, in some cases with fatal consequences. In vitro testing of specific Immunoglobin E (IgE) reactivities is thought to be able to significantly improve diagnostic accuracy and management in primary care. IgE plays a significant role in allergic conditions. Current methods for the sensitive and accurate detection of specific IgE reactivities are expensive; require significant sample preparation and investment in equipment. There is a need to provide a cheap, rapid, sensitive and specific test for IgE reactivities.

In a recent HOT article, a group of Swedish and Dutch Scientists describe a paper based lateral flow microarray for rapid allergy diagnostics. One of the authors, Jesper Gantelius of the Science for Life Laboratory, highlights “There is a rapid worldwide increase in atopic disorders and asthma without a clear understanding of the underlying cause. We have developed a paper-based microarray assay that could be used to rapidly and cost-efficiently evaluate a large number of specific IgE sensitisation’s in a primary care setting. The device may come to aid doctors in the personalised management of individual patients, as well as allow public health bodies to gain a better insight into the rapid increase of allergy-related conditions.”

The group, led by Prof. Helene Andersson Svahn, describe exciting research that was able to detect the responses of 15 specific IgE responses from 35 clinical serum samples with an inter-assay variability of 12 % revealing good general agreement with a current multiplexed array-based methodology. Interestingly this process is fully scalable and all that is required for data feedback is a consumer-grade flatbed scanner or smartphone camera enabling point-of-care diagnostics.

A lateral flow paper microarray for rapid allergy point of care diagnostics

Thiruppathiraja Chinnasamy, Loes I. Segerink, Mats Nystrand, Jesper Gantelius and Helene Andersson Svahn

Liquid chromatography using nanofluidic chip and DIC-TLM

The field of separation science has been continually evolving to enable the separation of smaller volumes. This interdisciplinary field has required developments in capillary electrophoresis, microfluidics and new detection technologies such as plasmonic sensing and thermal lensing. 

Researchers from the Department of Applied Chemistry, University of Tokyo lead by Prof. Kitamori have shown the ability to perform femtolitre (1 x 10^-15) separation and detection of nonfluorescent samples in a nanofluidic device. Using an extended nanofluidic device the researchers were able to separate and detect nonfluorescent molecules for the first time. Previous detection methodologies relied mainly on laser-induced fluorescence. 

The researchers showed the ability of nanofluidic separation science combined with differential interference contrast thermal lens microscopy (DIC-TLM) to enable detection of 370 molecules in a 2.3 μm wide by 350 nm deep nanochannel with a separation efficiency of 150,000 plates/m. DIC-TLM is thermal lens microscopy with an increased detection limit by realising background-free photodetection using differential interference contrast. 

Amazingly the injection volume and number of molecules were estimate to be 21 fL (1 x 10^-15) and 250 zmol at the limit of detection. This limit of detection provides separation of a sample 8 orders of magnitude smaller that that possible with high-performance liquid chromatography. This injection volume is much smaller than a single cell and detection limit is similar to the number of typical protein molecules in a single cells. Providing a promising tool for single cell research. 

To read more about this research download the HOT article which is free to access until April 5^th 

Femtoliter-Scale Separation and Sensitive Detection of Nonfluorescent Samples in an Extended-Nano Fluidic Device
Hisashi Shimizu, Kazuma Mawatari and Takehiko Kitamori 
Analyst, 2014, Accepted Manuscript

The authors work features on the front cover of Issue 5

This blog has been written by Adam Davis, a Guest Web-Writer for Analyst and Analytical Methods.

Enteric coatings are used to protect acid labile active pharmaceutical ingredients upon entry into the stomach, allowing for controlled and sustained release of active ingredients to the small intestine later. Enteric coated formulations typically consist of a sugar core, a layer of active ingredient followed by the enteric coating. Using current analysis methods determining the thickness of these layers can take up to 24hrs.

In this article, which appears in Issue 5 of Analyst, researchers from University College Cork, Ireland and Kinetox, Netherlands, have demonstrated how Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS) can be used for rapid profiling of enteric coated spheres. The BARDS technique is a novel approach which utilises the acoustic signature of cores spheres and enteric coating as they dissolve, which arise as result of the changes in compressibility of the solvent as a compound dissolves in it. This alters the speed of sound through the solvent, which in turn changes the frequency in solution. The use of BARDS has important implications for manufacturing, quality assurance and stability testing for pharmaceuticals.

Rapid profiling of enteric coated drug delivery spheres via Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS)
D. Fitzpatrick, R. Evans-Hurson, Y. Fu, T. Burke, J. Krüse, B. Vos, S. G. McSweeney, P. Casaubieilh and J. J. Keating
Analyst, 2014, 139, 1000-1006
DOI: 10.1039/C3AN01809A

Early and accurate monitoring of pathogens such as Escherichia coli is critical for food and water safety, clinical diagnosis, and biosecurity. However there are a number of limitations to current detection methods such as cell culturing, and immunoassays. These drawbacks include non-specificity, insensitivity, as well as the requirement of long analysis time, intensive labor, and extensive sample purification. To address some of these limitations, Christopher Pöhlmann and his colleagues from the University of Bayreuth in Germany have developed a lateral flow device based on a sandwich assay design using gold nanoparticle-oligonucleotides to detect ribosomal RNA of E. coli. The new device is able to provide specific detection of E. coli within 25 minutes and requires no signal amplification step.

A Lateral Flow Assay for Detection of E. coli Ribosomal RNA

Find out more about this discovery by reading the full paper below, which is free to download until March 7th:

A lateral flow assay for identification of Escherichia coli by ribosomal RNA hybridization
Christopher Pöhlmann, Irina Dieser and Mathias Sprinzl
Analyst, 2014, 139, 1063-1071
DOI: 10.1039/C3AN02059B

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