![]() ![]() Apart from the amino and carboxylate units common to all amino acids, tryptophan has no chemically reactive side chain. The development of synthetic receptors for tryptophan based on the principle of molecular recognition is an attractive design strategy to enable its recognition and quantification in biological matrices. State-of-the-art HPLC methods used to determine Trp levels in biofluids require cumbersome treatments, e.g., deproteinization of blood serum 25, and therefore have little prospects for future routine use in point-of-care units, ambulances, or general medical practices. Consequently, Trp is an analyte of high interest as well as a therapeutic target, as its concentration levels in blood and urine correlate, e.g., with cardiovascular and neurodegenerative diseases as well as the risk of sepsis progression (see Supplementary Table 1 for selected examples) 20, 21, 23, 25. Moreover, many metabolites and neurotransmitters, essential for regulating inflammations, energy homeostasis, and behavior, are routed in the tryptophan metabolism 22, 23, 24. The amino acid tryptophan (Trp) is an important metabolite as it is an essential building block in protein biosynthesis, a precursor for serotonin and melatonin, and the initial molecule of the kynurenine pathway 20, 21. Furthermore, the absorptivity and autofluorescence of urine and blood (serum) pose additional challenges for optical-based sensing methods. In particular, the various bioactive small molecules present in biofluids, combined with high concentrations of interfering proteins and salts, cause a highly complex matrix environment that fundamentally differs from the typically used solvent mixtures, deionized water, or low salt buffers 1, 19. ![]() Detecting biologically or medically relevant metabolites in biofluids remains challenging as reported optical chemosensors based on host–guest chemistry show deficiencies regarding affinity, selectivity, signal transduction, and stability 1, 17, 18. These successes are the exception rather than the rule and benefit from the comparably high concentration (in the mM range) of these target analytes. Optical chemosensor-based devices for routine metal cation sensing (via ionophores) and glucose monitoring (via boronic acids) have already reached clinics and personal homes 1, 14, 15, 16. Simple-to-use, fast-responding, and inexpensive chemosensors operating through molecular recognition principles in combination with easy-to-use instrumental setups are thus highly sought-after alternatives 9, 10, 11, 12, 13. However, the detection and quantification of biomarkers is so far mostly limited to clinical laboratories that are equipped with technical instruments such as high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS) or nuclear magnetic resonance (NMR) capacities 6, 7, 8. Sensing small biomolecules, such as amino acids and their derivatives, is important in molecular diagnostics and personalized medicine 1, 2, 3, 4, 5. Our system overcomes the limitations of current supramolecular host-guest chemosensors and will foster future applications of supramolecular sensors for molecular diagnostics. Printed sensor chips with surface-immobilized rotaxane-microarrays are used for fluorescence microscopy imaging of tryptophan. Moreover, this chemosensor enables emission-based high-throughput screening in a microwell plate format and can be used for label-free enzymatic reaction monitoring and chirality sensing. Here we introduce a cucurbituril-based rotaxane chemosensor feasible for sensing the health-relevant biomarker tryptophan at physiologically relevant concentrations, even in protein- and lipid-containing human blood serum and urine. Instead of following the established strategy of developing alternative synthetic binders with improved affinities and selectivity, we report a molecular engineering approach that addresses this biofluid challenge. Sensing small biomolecules in biofluids remains challenging for many optical chemosensors based on supramolecular host-guest interactions due to adverse interplays with salts, proteins, and other biofluid components.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |