Julian Gordon

Analytical Sensitivity Limits for Lateral Flow Immunoassays

A plethora of literature describes the use of lateral flow immunoassays (LFIA). Only a fraction of that contains information about possible analytical sensitivity or limit of detection. Accordingly, we have undertaken a comprehensive survey of the literature in PubMed and present here that fraction that has information on limits of detection or analytical sensitivity. Further detail of the search strategy is at http://www.finddiagnostics.org/news/resources/gordon\_michael\_latflow_immunoassays.pdf. In general, there is a need for rapid tests, such as LFIA, capable of being performed by unskilled operators yet providing rapid and reliable results in areas such as diagnosis of diseases in developing countries (1)(2), emergency room use (3), and biodefense(4). The utility of such tests is enhanced by the ability to determine analytes at very low concentrations. In LFIA, sample is added, the analyte and label are subjected to chromatography-like …

Discerning Trends in Multiplex Immunoassay Technology with Potential for Resource-Limited Settings

BACKGROUND In the search for more powerful tools for diagnoses of endemic diseases in resource-limited settings, we have been analyzing technologies with potential applicability. Increasingly, the process focuses on readily accessible bodily fluids combined with increasingly powerful multiplex capabilities to unambiguously diagnose a condition without resorting to reliance on a sophisticated reference laboratory. Although these technological advances may well have important implications for the sensitive and specific detection of disease, to date their clinical utility has not been demonstrated, especially in resource-limited settings. Furthermore, many emerging technological developments are in fields of physics or engineering, which are not readily available to or intelligible to clinicians or clinical laboratory scientists. CONTENT This review provides a look at technology trends that could have applicability to high-sensitivity multiplexed immunoassays in resource-limited settings. Various technologies are explained and assessed according to potential for reaching relevant limits of cost, sensitivity, and multiplex capability. Frequently, such work is reported in technical journals not normally read by clinical scientists, and the authors make enthusiastic claims for the potential of their technology while ignoring potential pitfalls. Thus it is important to draw attention to technical hurdles that authors may not be publicizing. SUMMARY Immunochromatographic assays, optical methods including those involving waveguides, electrochemical methods, magnetorestrictive methods, and field-effect transistor methods based on nanotubes, nanowires, and nanoribbons reveal possibilities as next-generation technologies.

Protein Microarrays: Before the Elephant Got in the Room

I read with great interest the recent editorial in Clinical Chemistry on protein microarrays (1). “The Elephant in the Room” in its title refers to a long-ignored issue, namely the problems involved in standardization and normalization of data from immunoassays on protein microarrays. I would like to take this opportunity to review approaches to those issues in the first publications on protein arrays, hence my title. Kattah et al. (1) referred to the wide use of normalization via total immunoglobulin for antigen arrays, and the inability to correct for differences in the spotting of individual features. This imperfection notwithstanding, a 1982 publication on protein arrays (2) already grappled with this issue and showed a calibration curve of immunoglobulin concentration against a densitometric scan intensity. This was further elaborated in a subsequent publication (3), in which empirical equations were used …