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The Advantages of a Portable SPR Instrument

The need for a simple, fast, yet sensitive diagnostic, screening, and molecular characterization tool is indispensable in clinical and research applications. There is a demand for a portable device which is user-friendly, low cost, rapid, and portable. It should also provide a highly sensitive and specific assay in real-time [1]. A portable surface plasmon resonance (SPR) instrument may be the answer.

Ever since Biacore commercialized its first SPR instrument in 1990, there have been other manufacturers who have entered the SPR instrumentation area. SPR instruments have mostly been sold to large pharmaceutical companies for drug discovery purposes [2] [3]. Many of these commercial instruments require trained personnel to operate and are not easily accessible, especially from the cost point of view. As a result, we have started to see in recent years more portable SPR instruments being introduced in the life science market.

In this blog, we will discuss the differences and advantages of a portable SPR instrument over large and high throughput commercial SPR systems.

 

Portable SPR vs. Large SPR System

Large commercial instruments are commonly used to obtain binding kinetics of drug candidates at a high throughput screening (HTS) capacity. Although not designed for HTS, a portable SPR instrument has the advantage of being flexible that can be reconfigured for multiple purposes such as bio- and chemical sensing, characterization of binding interactions, and assay development. Therefore, one can use such a portable SPR to perform any of these tasks in a rapid and easy manner. Another advantageous feature of a portable SPR is its modularity. For example, a portable SPR can be integrated with other add-on accessories to simultaneously perform spectroscopy, electrochemistry, and chromatography [3]. Table 1 gives an overview of the differences between a portable SPR and a large SPR system.

 

Table 1. Comparison of large and portable SPR instruments

  Large SPR System Small SPR System
Accessibility Accessible often only in centralized labs through advanced booking Any benchtop or even off-site, anytime
Consumable Cost High Low cost sensor chips ranging from a few to tens of dollars per chip
Maintenance Cost High, yearly contract Low to none
Type of Operator Trained personnel specifically for each SPR system Any researcher, clinician, postdoc, or student
Applications Binding kinetics of drug candidates Bio-/chemosensing, characterization of binding interactions, assay development
Modularity No Yes
 

Portable P4SPR™ from Affinité Instruments

Affinité Instruments has developed a portable P4SPR (Figure 1) to make SPR much more accessible to researchers in various types of biomolecular labs. In order to make the instrument robust, optical components are specially designed to be fixed, non-moving parts. [3]. In particular, P4SPR uses wavelength interrogation which significantly drives down manufacturing and maintenance cost [3]. P4SPR is very compact with the size of a lunchbox, ideal for use in small areas or in rural settings. It allows researchers to do on-site, real-time testing without relying on the availability to centralized lab facilities. Table 2 below summarizes the benefits to researchers from having P4SPR in their disposal.
Figure 1. Image of a quad inlet P4SPR™ instrument. Notice the easy-accessible injection ports and the four-channel microfluidic cell which can accommodate up to 4 samples.

Table 2. Features and benefits of the P4SPR

 Features Benefits
Compact, size of a lunchbox Portability
Thin-film sensor Highly sensitive to region ~200 nm from sensor surface. Well established area as opposed to localized SPR (LSPR)
Wavelength interrogation mode Low equipment and maintenance costs, robust, and user-friendly
Label-free sample preparation No need to buy purification kits and reagents. No effect on sample for kinetics and affinity.
Setup time to first analysis in less than 10 minutes Simple setup
Real-time output Fast results 
Triplicate multichannel microfluidic cell with separate reference channel Simultaneous acquisition of triplicate measurements Reference corrects for any fluctuation in temperature and bulk refractive index changes
Direct injection with micropipette Long contact time for slow kinetics, Low sample volume
Integration with other techniques such as spectroscopy, microscopy, and electrochemistry Flexibility in experimental setup and applications
Simplified software control with GUI
Real-time monitoring, data processing, and quantification
 

Portability and Flexibility is the Key

P4SPR™ has been used in pre-clinical research in areas such as the detection of a breast cancer biomarker, small peptides, DNA, antibodies, explosives, and early-stage drug development screening [3]. For instance, it helped elucidate a clear picture of the binding interactions between a transmembrane protein and small peptides by determining the equilibrium dissociation constants from the resultant affinity curves [4]. Another example of P4SPR’s portability advantage is the outdoor detection of explosives traces near a grenade range at a military base in both summer and winter time [5]. The need to prepare and transport the samples to a centralized facility was eliminated by allowing for continuous on-site, real-time monitoring over days and weeks. In this case, the time it took for site setup including sensor calibration, sample preparation, and data gathering and analysis can be as little as 1 hour in total, much less than the turnaround time of days with centralized testing [5]. The application wheel below illustrates the many areas that a portable SPR can be applied.
 

 

Thank you for reading and watch out for additional blogs discussing SPR related topics such as wavelength vs. angle interrogation, planar SPR vs. nanoparticle localized SPR, and multiple channel SPR.

Written by April Wong, Affinité Instruments
References
  1. Julien Breault-Turcot and Jean-François Masson, “Nanostructured substrates for portable and miniature SPR biosensors,Anal. Bioanal. Chem., vol. 403, p. 1477, 2012.

  2. Arnoud Marquart, “SPRpages,” 2006-2020. [Online]. [Accessed 7 September 2020].

  3. Affinité Instruments

  4. Carolina Gomez-Diaz, Benoîte Bargeton, Liliane Abuin, Natalia Bukar, Jaime H. Reina, Tudor Bartoi, Marion Graf, Huy Ong, Maximilian H. Ulbrich, Jean-François Masson, Richard Benton, “A CD36 ectodomain mediates insect pheromone detection via a putative tunnelling mechanism,Nature Communications, vol. 7, p. 11866, 2016.

  5. Thibault Brulé, Geneviève Granger, Natalia Bukar, Clarisse Deschênes-Rancourt, Thierry Havard, Andreea R. Schmitzer, Richard Martel, and Jean-François Masson, “A field-deployed surface plasmon resonance (SPR) sensor for RDX quantification in environmental waters,Analyst, vol. 142, p. 2161, 2017.