Potential use of a dried saliva spot (DSS) in therapeutic drug monitoring and disease diagnosis

Abstract

In recent years, scientific researchers have increasingly become interested in noninvasive sampling methods for therapeutic drug monitoring and disease diagnosis. As a result, dried saliva spot (DSS), which is a sampling technique for collecting dried saliva samples, has been widely used as an alternative matrix to serum for the detection of target molecules. Coupling the DSS method with a highly sensitive detection instrument improves the efficiency of the preparation and analysis of biological samples. Furthermore, dried blood spots, dried plasma spots, and dried matrix spots, which are similar to those of the DSS method, are discussed. Compared with alternative biological fluids used in dried spot methods, including serum, tears, urine, and plasma, saliva has the advantage of convenience in terms of sample collection from children or persons with disabilities. This review aims to provide integral strategies and guidelines for dried spot methods to analyze biological samples by illustrating several dried spot methods. Herein, we summarize recent advancements in DSS methods from June 2014 to March 2021 and discuss the advantages and disadvantages of the key aspects of this method, including sample preparation and method validation. Finally, we outline the challenges and prospects of such methods in practical applications.

Keywords: Disease diagnosis; Dried saliva spot; Human saliva; Therapeutic drug monitoring.

Graphical abstract

Fig. 1

Types of filter paper used in the dried saliva spot (DSS) method: (A) Whatman FTA™ DMPK-C card; (B) color-indicating card; (C) filter paper for the determination of lidocaine; (D) filter paper for the determination of uric acid; (E) Whatman™ 903 protein saver card; and (F) solid-material filter paper made of an alginate and chitosan foam. (Reprint from Refs. [[18], [23], [26], [33]] with permission.)

Fig. 2

Different types of equipment for cutting filter paper for dried saliva spot (DSS) testing: (A) manual hole punch and (B) semi-automated cutter from TOMTEC. (Reprint from Ref. [34] with permission.)

Fig. 3

Preparation and brief schematic of dried saliva spot (DSS) for determination content of uric acid (UA). LC-UV: liquid chromatography-ultraviolet; IS: internal standard. (Reprint from Ref. [26] with permission.)

Fig. 4

Processing steps of dried matrix spot (DMS) sample extraction. IS: internal standard. (Reprint from Refs. [[23], [35]] with permission.)

Fig. 5

Schematic diagrams of the dried herbal medicines spot (DHMS) method. HPLC: high performance liquid chromatography. (Reprint from Ref. [83] with permission.)