The
use of saliva as a diagnostic biofluid has been increasing
in recent years, thanks to the identification and validation of new
biomarkers and improvements in test accuracy, sensitivity, and precision
that enable the development of new noninvasive and cost-effective
devices. However, the lack of standardized methods for sample collection,
treatment, and storage contribute to the overall variability and lack
of reproducibility across analytical evaluations. Furthermore, the
instability of salivary biomarkers after sample collection hinders
their translation into commercially available technologies for noninvasive
monitoring of saliva in home settings. The present review aims to
highlight the status of research on the challenges of collecting and
using diagnostic salivary samples, emphasizing the methodologies used
to preserve relevant proteins, hormones, genomic, and transcriptomic
biomarkers during sample handling and analysis.