Biomarker-mediated disruption of coffee-ring formation as a low resource diagnostic indicator.

Trantum JR, Wright DW, Haselton FR
Langmuir. 2012 28 (4): 2187-93

PMID: 22148855 · DOI:10.1021/la203903a

The ring pattern resulting from the unique microfluidics in an evaporating coffee drop is a well-studied mass transport phenomenon generating interest in the research community mostly from a mechanistic perspective. In this report, we describe how biomarker-induced particle-particle assemblies, magnetic separation, and evaporation-driven ring formation can be combined for simple pathogen detection. In this assay design, the presence of biomarkers causes self-assembly of a magnetic nanoparticle and a fluorescently labeled micrometer-sized particle. A small spherical magnet under the center of the drop prevents these assemblies from migrating to the drop's edge while a nonreactive control particle flows to the edge forming a ring pattern. Thus the presence or absence of biomarker results in distinctly different distributions of particles in the dried drop. Proof-of-principle studies using poly-L-histidine, a peptide mimic of the malaria biomarker pfHRPII, show that the predicted particle distributions occur with a limit of detection of approximately 200-300 nM.

© 2011 American Chemical Society

MeSH Terms (13)

Antigens, Protozoan Biomarkers Biomimetic Materials Clinical Chemistry Tests Fluorescent Dyes Histidine Limit of Detection Magnets Malaria Microfluidic Analytical Techniques Nanoparticles Protozoan Proteins Volatilization

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