title: Raman Characterization of Nanoparticle Transport in Microfluidic Paper-Based Analytical Devices (μPADs).
abstract: There is great interest in the use of microfluidic paper-based analytical devices (μPADs) for low-cost diagnostics. In this contribution, we illustrate the utility of Raman spectral imaging for both μPAD characterization and for quantification of the transport of applied reagents and analytes within these devices. We evaluated the transport of nanoscale particles within μPADs using a suite of differentially functionalized gold (AuNP) and silver (AgNP) nanoparticles with diameters of 8-64 nm. Nanoparticle transport within the cellulose matrix was characterized by collection of both Raman and surface-enhanced Raman spectroscopy (SERS) spectral maps that enabled differentiation of cellulose fibers and characterization of analyte deposition patterns. The transport of citrate (cit), BSA, PEG, PVP, and DNA functionalized AuNP and AgNP in wax-printed μPADs was primarily affected by nanoparticle surface chemistry rather than particle size or core composition. Sample pH (3-10) influenced the transport of 15 nm BSA-cit-AuNP, but not 15 nm cit-AuNP, because of the effects of solution pH on the charge and conformation of BSA. Derjaguin, Landau, Verwey, and Overbeek theory (DLVO) and extended DLVO (xDLVO) theory are used to explain the collected experimental results.
authors: Department of Civil and Environmental Engineering and Institute of Critical Technology and Applied Science (ICTAS), Virginia Tech, 418 Durham Hall, Blacksburg, Virginia 24060-0246, United States.
authors: Rebecca Halvorson
authors: RH
authors: Lahr
authors: Department of Civil and Environmental Engineering and Institute of Critical Technology and Applied Science (ICTAS), Virginia Tech, 418 Durham Hall, Blacksburg, Virginia 24060-0246, United States.
authors: Grant C
authors: GC
authors: Wallace
authors: Department of Civil and Environmental Engineering and Institute of Critical Technology and Applied Science (ICTAS), Virginia Tech, 418 Durham Hall, Blacksburg, Virginia 24060-0246, United States.
authors: Peter J
authors: PJ
authors: Vikesland
mesh_terms: D002623:Chemistry Techniques, Analytical / Q000295:instrumentation*; D004058:Diffusion; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006046:Gold / Q000032:analysis / Q000737:chemistry*; D056656:Lab-On-A-Chip Devices; D053768:Metal Nanoparticles / Q000032:analysis / Q000737:chemistry* / Q000648:ultrastructure; D046228:Microarray Analysis / Q000295:instrumentation; D010209:Paper; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D006046:Gold
keywords: DLVO; Hamaker constants; cellulose; nanoparticle transport; surface-enhanced Raman spectroscopy (SERS); wax-printed microfluidic paper based analytical devices (μPADs)