Review: Recent progress in fluorescent molecular systems for the detection of disease-related biomarkers in biofluids

The use of biofluids as a diagnostic tool for chronic health conditions has been gaining traction in recent years. These fluids, which can be obtained non-invasively (such as urine, saliva and sweat) or invasively (such as blood plasma, blood serum, synovial fluid and cerebrospinal fluid (CSF)), offer a convenient and rapid means of diagnosis. In this article, we will review the recent progress in developing probes for detecting biomarkers, such as biothiols, albumins, biogenic amines, amino acids, enzymes, bilirubin, creatinine, carbohydrates, neurotransmitters, nucleotides, carbamides and ions, in biofluids. We will also examine the photophysical properties of these probes and their potential applications in real or artificial biofluid samples. Additionally, we will summarize the properties of the probes, including their selectivity, sensitivity, photostability, and detection limits. The review also emphasizes the urgency for the development of organic molecular probes that can detect biomarkers in non-invasive biofluids such as urine, saliva, sweat, and breath. All the probes presented in this review have proven applications in real or artificial biofluid samples. The cost efficiency and reliability of the organic molecular probes have made them an excellent choice for developing paper-based strips and point-of-care (POC) portable devices for diagnosing and monitoring chronic disorders.