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.

With the rapid development of modern molecular biology, microRNA (miRNA) has been demonstrated to be closely associated with the occurrence and development of tumors and holds significant promise as a biomarker for the early detection, diagnosis, and treatment of cancer and other diseases. Therefore, detecting miRNA and analyzing it to determine its biological functions are of great significance for the screening and diagnosis of diseases. However, the intrinsic characteristics of miRNAs, including their low abundance, short sequence lengths, and high family-specific sequence homology, render traditional detection methods such as Northern blot hybridization, microarray use, and reverse transcription quantitative PCR (RT-qPCR) inadequate for meeting the stringent requirements of clinical detection in biological samples, a task requiring accuracy, rapidity, high detection power, specificity, and cost-effectiveness. In recent years, a substantial amount of effort has been put into developing innovative methodologies to address these challenges. In this review, we aim to provide a comprehensive overview of the recent advancements in these methodologies and their applications in clinical biological sample detection for disease diagnosis.

A duplex-specific nuclease (DSN) and catalytic hairpin assembly (CHA)-mediated dual amplification method has been developed. This strategy achieved a sensitive limit of detection and excellent selectivity for miR-146b detection.