Rapid saliva processing techniques for near real-time analysis of salivary steroids and protein.
BACKGROUND
Point-of-care (POC) measurements using saliva samples have immense potential to assess systemic health and wellbeing, but sample viscosity and contaminants can affect analyses. We sought a portable clean-up method for whole saliva appropriate for use with POC measurement techniques such as biosensors.


METHODS
Whole saliva from each of 13 male subjects was split into 5 fractions. Each fraction was treated with a different clean-up process: a freeze-thaw-centrifuge (FTC) step; centrifugation alone; or passage through a Mini-UniPrep polyethersulfone filter, cotton Salivette, or foam Oracol device. Following clean-up, each subject's treated saliva fractions were assayed for cortisol, testosterone, dehydroepiandrosterone (DHEA), and protein concentrations. The effects of clean-up methods on nonspecific binding (NSB) in a biosensor were also assessed.


RESULTS
Compared with FTC, no analytes were affected by centrifugation alone. Cotton Salivettes significantly altered all analytes, with increases in cortisol (+64%), testosterone (+126%), and DHEA (off-scale) levels, and decreased protein (-21%) and biosensor NSB (-75%). Oracol foam devices decreased DHEA levels by 28%. Mini-UniPrep filtration decreased testosterone (-45%) and DHEA (-66%) concentrations while increasing cortisol (+40%).


CONCLUSIONS
No method was optimal for all analytes, highlighting the need for validation of saliva treatment methods before their adoption in rapid POC analyses.
Atkinson
Kelly R
KR
Functional Foods and Health Programme,The Horticultural and Food Research Institute of New Zealand Ltd., Auckland, New Zealand. katkinson@hortresearch.co.nz
Lo
Kim R
KR
Payne
Steve R
SR
Mitchell
John S
JS
Ingram
John R
JR
D000328:Adult; D002498:Centrifugation; D003687:Dehydroepiandrosterone / Q000032:analysis; D005374:Filtration; D005615:Freezing; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems; D011863:Radioimmunoassay; D012463:Saliva / Q000737:chemistry*; D012471:Salivary Proteins and Peptides / Q000032:analysis; D013048:Specimen Handling / Q000379:methods*; D020349:Surface Plasmon Resonance; D013739:Testosterone / Q000032:analysis
D012471:Salivary Proteins and Peptides; D013739:Testosterone; D003687:Dehydroepiandrosterone; D006854:Hydrocortisone