Localized Surface Plasmon Resonance for Bioprocess Development, Monitoring, and Validation
BioProcess International, Vol. 9, No. 8, September 2011, pp. 70–75
Academic laboratories have embraced localized surface plasmon resonance (LSPR) as the “new wave” of label-free technology (1). This technique is based on the ability of colloidal metal nanoparticles or nanostructured metallic films to absorb light in a narrow wavelength range. Metal nanostructures “sense” changes occurring at their surfaces by shifting the frequency of the light they absorb or reflect. As a consequence, a basic LSPR system requires only optical fibers, a source of white light, and a detector (1,2). The simplicity of LSPR instrumentation contrasts with its exquisite sensitivity. Binding events and functional activity of nucleases (3) and proteases (4) can be monitored and quantified in real time based on observation of a single 20-nm nanoparticle — probably one of the world’s smallest biosensing supports (5).
Nanostructured metallic films, rather than isolated metal nanoparticles, enable commercial endeavors by their robust and reproducible nature. With recent advances in nanofabrication and characterization, stable metal films can be manufactured at a large and cost-effective scale on a wide range of surfaces (2). Such films retain their nanostructures and the physical properties of nanoparticles. As a result, LSPR technology is quickly moving from proof-of-principle experiments to commercialization.
Key features of the technology include its marginal bulk effect and compatibility with various matrices, including cell media and sera. In addition, LSPR can accommodate label-free and labeled implementations, with the latter pushing its detection limits into the femto- to picomolar range (2). Various approaches using the same core technology allow detection of biologics in concentrations spanning from trace contaminants to levels of therapeutic antibodies in fermentation broths and cell culture supernatants. Furthermore, LSPR assays can be performed either at line or in line. As a result, this is a platform particularly well suited for all stages of bioprocessing, from development to monitoring and validation…
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