Surface small biomolecule detection

Calculations have been performed to estimate the detection limit of the porous silicon waveguide biosensor based on the percent of optical power interacting with biomolecules in the waveguide (25). The sensor is capable of detecting pictogram quantities of small molecules in a 1 mm surface area. The detection limit depends on the number of probe molecules immobiUzed on the pore walls, the size of the biomolecules relative to the size of the pores, and the efficiency at which the probe molecules capture the target species. 

A RAM column functions through a size exclusion mechanism. Large biomolecules such as proteins are restricted from the adsorptive surfaces inside silica particles. Small analyte molecules are able to penetrate into the inner surfaces of the particles. As a result, protein molecules pass through the column rapidly and analytes of interest are retained on the adsorptive sites. Depending on the application, the analyte molecules are directed to MS for detection or transferred onto an analytical column for separation prior to MS detection. Detailed applications are discussed in a recent review.8... 

Inner slip, between the solid wall and an adsorbed film, will also influence the surface-liquid boundary conditions and have important effects on stress propagation from the liquid to the solid substrate. Linked to this concept, especially on a biomolecular level, is the concept of stochastic coupling. At the molecular level, small fluctuations about the ensemble average could affect the interfacial dynamics and lead to large shifts in the detectable boundary condition. One of our main interests in this area is to study the relaxation time of interfacial bonds using slip models. Stochastic boundary conditions could also prove to be all but necessary in modeling the behavior and interactions of biomolecules at surfaces, especially with the proliferation of microfluidic chemical devices and the importance of studying small scales. 

MEMS-Based Acoustic Wave Biosensors Introduction A MEMS-based acoustic wave biosensor is a chemical sensor which detects changes in resonant frequency of a mechanical resonator when biomolecules are adsorbed on the surface of a biologically active membrane. Since frequency change can be measured very precisely, very small mass changes can be measured. This leads to high sensitivity of the biosensors. Typical acoustic wave biosensors are bulk acoustic wave (BAW) and surface acoustic wave (SAW) sensors. 

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