Since the first application of the surface plasmon resonance (SPR) phenomenon for sensing almost two decades ago, this method has made great strides both in terms of instrumentation development and applications. SPR sensor technology has been commercialized and SPR biosensors have become a central tool for characterizing and quantifying biomolecular interactions. This paper attempts to review the major developments in SPR technology. Main application areas are outlined and examples of applications of SPR sensor technology are presented. Future prospects of SPR sensor technology are discussed.

Surface plasmon resonance sensors: review

Surface plasmon resonance (SPR) biosensors are optical sensors exploiting special electromagnetic waves—surface plasmon-polaritons—to probe interactions between an analyte in solution and a biomolecular recognition element immobilized on the SPR sensor surface. Major application areas include detection of biological analytes and analysis of biomolecular interactions where SPR biosensors provide benefits of label-free real-time analytical technology. This paper reviews fundamentals of SPR affinity biosensors and discusses recent advances in development and applications of SPR biosensors.

Present and future of surface plasmon resonance biosensors.

Plant cell cultures: Chemical factories of secondary metabolites

Molecular imprinting science and technology: a survey of the literature for the years up to and including 2003

We describe the results of a numerical investigation of the dynamics of breakup of streams of immiscible fluids in the confined geometry of a microfluidic T-junction. We identify three distinct regimes of formation of droplets: squeezing, dripping and jetting, providing a unifying picture of emulsification processes typical for microfluidic systems. The squeezing mechanism of breakup is particular to microfluidic systems, since the physical confinement of the fluids has pronounced effects on the interfacial dynamics. In this regime, the breakup process is driven chiefly by the buildup of pressure upstream of an emerging droplet and both the dynamics of breakup and the scaling of the sizes of droplets are influenced only very weakly by the value of the capillary number. The dripping regime, while apparently homologous to the unbounded case, is also significantly influenced by the constrained geometry; these effects modify the scaling law for the size of the droplets derived from the balance of interfacial and viscous stresses. Finally, the jetting regime sets in only at very high flow rates, or with low interfacial tension, i.e. higher values of the capillary number, similar to the unbounded case.

/pdf/transition-from-squeezing-to-dripping-in-a-microfluidic-t-12akqtfl9y.pdf

Transition from squeezing to dripping in a microfluidic T-shaped junction

We propose a novel ethylenediamine plasma-polymerized film matrix that is deposited on gold surfaces for use in surface plasmon resonance immunosensing. The films formed on the gold surfaces are extremely thin (∼100 nm), are homogeneous, demonstrate good adhesion, have a flat profile, and incorporate amino groups to introduce a chemical functionality. A sensor chip made with the film has many advantages when compared with conventionally used designs such as carboxylated dextran hydrogels. For example, a sensor chip made with the film shows a better sensor response than a conventional design partly because antibodies are densely and two-dimensionally immobilized onto the surface of the plasma-polymerized film.

A Plasma-Polymerized Film for Surface Plasmon Resonance Immunosensing

Integral to the development of embryonic stem cell therapeutic strategies for hepatic disorders is the iden- tification and establishment of a controllable hepatic differ- entiation strategy. In order to address this issue we have established an alginate microencapsulation approach which provides a means to modulate the differentiation process through changes in key encapsulation parameters. We report that a wide array of hepatocyte specific markers is expressed by cells differentiated during a 23-day period within an alginate bead microenvironment. These include urea and albumin secretion, glycogen storage, and cyto- chrome P450 transcription factor activity. In addition, we demonstrate that cellular aggregation is integral to the control of differentiation within the bead environment and this process is mediated by the E-cadherin protein. The temporal expression of surface E-cadherin and hepa- tocyte functional expression occur concomitantly and both cellularaggregation andalbumin synthesisare blockedinthe presence of anti E-cadherin immunoglobulin. Furthermore, by establishing a compartmental model of differentiation, which incorporates this aggregation phenomenon, we can optimize key encapsulation parameters. Biotechnol. Bioeng. 2007;98: 631-644.

Control of hepatic differentiation via cellular aggregation in an alginate microenvironment.

Immobilized plant cell reactors

Addition of an ethylene precursor, ethephon, was studied in plant-cell-suspension cultures of Coffea arabica and Thalictrum rugosum as an enhancer of secondary metabolite production. In both cases the compound was able to stimulate alkaloid production, even though the biochemical pathways are widely different. This suggests that ethephon, or more directly ethylene, may be valuable in increasing secondary metabolite levels in a variety of cell-suspension culture systems.

Henrik Pedersen

Papers

A Plasma-Polymerized Film for Surface Plasmon Resonance Immunosensing

Control of hepatic differentiation via cellular aggregation in an alginate microenvironment.

Immobilized plant cell reactors

Ethephon Enhancement of Secondary Metabolite Synthesis in Plant Cell Cultures

Increasing secondary metabolite production in plant-cell culture by redirecting transport