Reagent-free DOPA-dioxygenase colorimetric biosensor for selective detection of L-DOPA

Colorimetric and Fluorometric Paper-Based Assay for Cu2+ Detection Based on Green Synthesis of 2-Aminoterephthalic Acid-Derived Pigments

“…DOPA-extradiol-4,5-dioxygenase is a key enzyme involved in the 4,5 cleavage of aromatic rings on l -DOPA for the synthesis of betalamic acid (Figure S1A). , Natural betalain pigments possess a structural feature containing betalamic acid, which undergoes a Schiff condensation reaction with free amino groups or indoline-containing structures to form betaxanthins or betacyanins, respectively. − Note that a variety of structural motifs in the cyclo-DOPA moiety could affect the fluorescence characteristics of betanin. − In this paper, we have systematically investigated the effects of the electron-donating groups and electron-withdrawing groups in aromatic amines and their effects on betaxanthin fluorescence.…”

MycoRed: Betalain pigments enable in vivo real-time visualisation of arbuscular mycorrhizal colonisation

“…Betalains are naturally occurring tyrosine-derived water-soluble pigments, comprising yellow to orange betaxanthins and red to purple betacyanins. Betalains have a number of bioindustrial applications, as natural food colourants and antioxidants [21] and as biosensors [22][23][24][25][26]. Betalains were first discovered in plants, where they are unique to the flowering plant order Caryophyllales [27], but have also been reported in the proteobacterium Gluconacetobacter diazotrophicus [28] and the fungi Amanita [29] and Hygrocybe [30].…”

“…Elucidation of these core enzymatic steps has enabled the engineering of the betalain biosynthetic pathway in a wide range of heterologous hosts, including microbes such as Saccharomyces cerevisiae [38]; plant model organisms like Arabidopsis thaliana, Nicotiana tabacum, and Petunia hybrida [31,39,40]; and a diversity of crops such as Oryza sativa (rice), Solanum lycopersicum (tomato), Solanum tuberosum (potato), and Solanum melongena (aubergine) [40,41]. Betalains have been used as biosensors in a number of heterologous contexts to report increased production of metabolites, such as tyrosine, dopamine, and ʟ-DOPA in Escherichia coli and Nicotiana benthamiana [23,24,26], to measure metabolic flux between competing pathways in the synthesis of benzylisoquinoline alkaloids (BIAs) in S. cerevisiae [22] and for the detection of copper by heavy metal-resistant bacteria in bioremediation processes [25]. In plants, specific promoters have been successfully used to target betalain production in specific tissues such as fruits and seed endosperm [40][41][42].…”

Gold-Specific Biosensor for Monitoring Wastewater Using Genetically Engineered Cupriavidus metallidurans CH34

“…Microbial biosensors use a natural regulatory circuit within a microorganism to trigger the production of a measurable signal upon sensing the target analyte . A wide range of output signals have been employed in biosensors, including (1) fluorescence proteins, such as red fluorescent protein (mRFP1), green fluorescent protein (GFP), and cyan fluorescent protein (CFP), etc., , (2) bioluminescence, such as the luciferase and luciferase subunit (nanoluciferase, Nluc), − and (3) pigments, such as lycopene, β-carotene, violacein, and betaxanthin . To reduce the cost of purchasing and operating instruments, these output signals are commonly used to achieve reliable reading at a low cost.…”