Smart microsampling in protein analysis
Dried Blood Spots (DBS) as sampling technique has been around for decades to allow analysis of diagnostic biomarkers and small molecular sized drugs in whole blood dried on filter paper. It has proven its use in neonatal screening for inborn metabolic diseases. Due to its convenient sampling and further handling (in dried condition the sample cards can be transported by regular mail without the need of refrigeration) it allows sampling at home as well as in remote areas.
For the last five years, we have been exploring use of DBS and other matrix spots (serum, plasma, urine) in MS-based protein analysis, using both water-soluble sampling material, conventional DBS filter paper and volumetric absorptive microsampling (VAMS). We have gathered general information about use of DBS and other microsampling techniques in protein analysis as well as demonstrated the potential of combining DBS with immunocapture enrichment to enable determination of low abundance protein markers from small volumes of dried sample.
DBS sampling for analysis of protein disease markers and biopharmaceuticals is however due to several practical limitations still challenging; upon arrival at the laboratory, several days are needed to extract and treat the proteins in such a way that they can be analyzed using LC-MS.
We therefore recently introduced the concept of “smart blood spot sampling”, where instant protein treatment is integrated in and combined with convenient blood spot sampling.
In other words, we try to integrate the necessary sample pretreatment steps (like protein trypsination or immunocapture) in the DBS card, allowing many of the necessary pretreatment steps to carried directly upon sampling (and subsequent postal transfer to the laboratory).