Theoretical limitations of quantification for noncompetitive sandwich immunoassays.

Immunoassays exploit the highly selective interaction between antibodies and antigens to provide a vital method for biomolecule detection at low concentrations. Developers and practitioners of immunoassays have long known that non-specific binding often restricts immunoassay limits of quantification (LOQs). Aside from non-specific binding, most efforts by analytical chemists to reduce the LOQ for these techniques have focused on improving the signal amplification methods and minimizing the limitations of the detection system.

Quantitative assessment of flow and electric fields for electrophoretic focusing at a converging channel entrance with interfacial electrode.

The electric field and flow field gradients near an electrified converging channel are amenable to separating and focusing specific classes of electrokinetic material, but the detailed local electric field and flow dynamics in this region have not been thoroughly investigated. Finite elemental analysis was used to develop a model of a buffer reservoir connected to a smaller channel to simulate the electrophoretic and flow velocities (which correspond directly to the respective electric and flow fields) at a converging entrance. A detailed PTV (Particle Tracking Velocimetry) study using charged fluorescent microspheres was performed to assess the model validity both in the absence and presence of an applied electric field.

Spatio-temporal image analysis of particle streaks in micro-channels for low-cost electro-hydrodynamic flow characterization.

Flow characterization is a primary analytical method for performance evaluation of microfluidic devices. With the increasing prevalence of microfluidic devices in recent years, there is a growing need for simple methods of automated flow estimation. In this work, a novel flow diagnostic technique based on image analysis of particle streaks is introduced, to characterize local flow velocities.

Dielectrophoretic mobility determination in DC insulator-based dielectrophoresis.

Insulator-based dielectrophoresis (iDEP) is a powerful tool for separating and characterizing particles, yet it is limited by a lack of quantitative characterizations. Here, this limitation is addressed by employing a method capable of quantifying the DEP mobility of particles. Using streak-based velocimetry the particle properties are deduced from their motion in a microfluidic channel with a constant electric field gradient.

Improved detectability and signal strength for rotating phase fluorescence immunoassays through image processing.

Fluorescence immunoassays based on rotating solid phase have shown promise of lowered detection limits, among other advantages. However, intrinsic background distortion effects have limited their utility. Here, novel image processing strategies are used to minimize these effects and improve the estimate of concentration and lower the detection limit.

Demonstration of sandwich and competitive modulated supraparticle fluoroimmunoassay applied to cardiac protein biomarker myoglobin.

Modulated supraparticle structures are used to improve sandwich and competitive fluoroimmunoassays. The improved methods are demonstrated on myoglobin, a key diagnostic protein for detection of heart damage. The resulting method uses microliter volumes with bovine serum samples doped with varying concentrations of equine myoglobin.