10 research outputs found
Digital, Ultrasensitive, End-Point Protein Measurements with Large Dynamic Range via Brownian Trapping with Drift
This communication shows that the concept of Brownian trapping with drift can be applied to improve quantitative molecular measurements. It has the potential to combine the robustness of end-point spatially resolved readouts, the ultrasensitivity of digital single-molecule measurements, and the large dynamic range of qPCR; furthermore, at low concentrations of analytes, it can provide a direct comparison of the signals arising from the analyte and from the background. It relies on the finding that molecules simultaneously diffusing, drifting (via slow flow), and binding to an array of nonsaturable surface traps have an exponentially decreasing probability of escaping the traps over time and therefore give rise to an exponentially decaying distribution of trapped molecules in space. This concept was tested with enzyme and protein measurements in a microfluidic device
Quantitative and Real-Time Detection of Secretion of Chemical Messengers from Individual Platelets â€
High-Throughput Density Measurement Using Magnetic Levitation
This work describes
the development of an integrated analytical
system that enables high-throughput density measurements of diamagnetic
particles (including cells) using magnetic levitation (MagLev), 96-well
plates, and a flatbed scanner. MagLev is a simple and useful technique
with which to carry out density-based analysis and separation of a
broad range of diamagnetic materials with different physical forms
(e.g., liquids, solids, gels, pastes, gums, etc.); one major limitation,
however, is the capacity to perform high-throughput density measurements.
This work addresses this limitation by (i) re-engineering the shape
of the magnetic fields so that the MagLev system is compatible with
96-well plates, and (ii) integrating a flatbed scanner (and simple
optical components) to carry out imaging of the samples that levitate
in the system. The resulting system is compatible with both biological
samples (human erythrocytes) and nonbiological samples (simple liquids
and solids, such as 3-chlorotoluene, cholesterol crystals, glass beads,
copper powder, and polymer beads). The high-throughput capacity of
this integrated MagLev system will enable new applications in chemistry
(e.g., analysis and separation of materials) and biochemistry (e.g.,
cellular responses under environmental stresses) in a simple and label-free
format on the basis of a universal property of all matter, i.e., density
Magnetic Levitation To Characterize the Kinetics of Free-Radical Polymerization
This
work describes the development of magnetic levitation (MagLev)
to characterize the kinetics of free-radical polymerization of water-insoluble,
low-molecular-weight monomers that show a large change in density
upon polymerization. Maglev measures density, and certain classes
of monomers show a large change in density when monomers covalently
join in polymer chains. MagLev characterized both the thermal polymerization
of methacrylate-based monomers and the photopolymerization of methyl
methacrylate and made it possible to determine the orders of reaction
and the Arrhenius activation energy of polymerization. MagLev also
made it possible to monitor polymerization in the presence of solids
(aramid fibers, and carbon fibers, and glass fibers). MagLev offers
a new analytical technique to materials and polymer scientists that
complements other methods (even those based on density, such as dilatometry),
and will be useful in investigating polymerizations, evaluating inhibition
of polymerizations, and studying polymerization in the presence of
included solid materials (e.g., for composite materials)