Point-of-care testing approaches : Research : Biotechnology : Science + Technology : National Physical Laboratory

Point-of-care testing approaches

Point-of-care testing (POCT) has a number of potential advantages but its introduction may also pose a new set of challenges:

Pros

Less reliance on subjective data (that provided by the patient)
Selection of treatments based on more objective data (i.e. stratified medicine)
Shorter decision times (no need to send samples away for analysis)
Frequent monitoring possible (important, e.g. for diabetes)

Cons

Potentially greater variation between test results (see standardisation)
The need to carry and store test reagents and dispose of samples hygienically
More complex data management
More devices, therefore more training

The best POCT technologies are simple, inexpensive, reliable, quantitative and meet a clear area of need (e.g. roadside detection of drugs of abuse). The Biotechnology Group has considerable experience assessing and developing different point-of-care testing approaches. One technology developed by the Group is an electrochemical immunoassay system that uses electro-active silver nanoparticles for analyte labelling, magnetic particles for analyte isolation and anodic stripping voltammetry for signal amplification (see graph). The patented approach is being commercialised by Argento Diagnostics Ltd, NPL's first spin out company.

Measurement of myoglobin (a marker for myocardial infarcation –
heart attack) with immunolabelled magnetic beads and silver
nanoparticles and anodic stripping voltametry. With a molecular
weight of 16700 Daltons, the dynamic range of the myoglobin
assay corresponds to 10 pM – 1 nM. Direct measurement of such
concentrations is difficult but the amplification factor available from
the silver nanoparticles (2 X 10^6 silver atoms per myoglobin
molecule) makes such determinations straightforward.