title: Quantum dots as optical labels for ultrasensitive detection of polyphenols.
abstract: Considering the fact that polyphenols have versatile activity in-vivo, its detection and quantification is very much important for a healthy diet. Laccase enzyme can convert polyphenols to yield mono/polyquinones which can quench Quantum dots fluorescence. This phenomenon of charge transfer from quinones to QDs was exploited as optical labels to detect polyphenols. CdTe QD may undergo dipolar interaction with quinones as a result of broad spectral absorption due to multiple excitonic states resulting from quantum confinement effects. Thus, "turn-off" fluorescence method was applied for ultrasensitive detection of polyphenols by using laccase. We observed proportionate quenching of QDs fluorescence with respect to polyphenol concentration in the range of 100 µg to 1 ng/mL. Also, quenching of the photoluminescence was highly efficient and stable and could detect individual and total polyphenols with high sensitivity (LOD-1 ng/mL). Moreover, proposed method was highly efficient than any other reported methods in terms of sensitivity, specificity and selectivity. Therefore, a novel optical sensor was developed for the detection of polyphenols at a sensitive level based on the charge transfer mechanism.
authors.affiliation: Fermentation Technology and Bioengineering Department, CSIR-Central Food Technological Research Institute, Mysore 570020, India.
authors.forename: Uchangi Satyaprasad
authors.initials: US
authors.lastname: Akshath
authors.affiliation: Fermentation Technology and Bioengineering Department, CSIR-Central Food Technological Research Institute, Mysore 570020, India.
authors.forename: Likitha R
authors.initials: LR
authors.lastname: Shubha
authors.affiliation: Fermentation Technology and Bioengineering Department, CSIR-Central Food Technological Research Institute, Mysore 570020, India.
authors.forename: Praveena
authors.initials: P
authors.lastname: Bhatt
authors.affiliation: Fermentation Technology and Bioengineering Department, CSIR-Central Food Technological Research Institute, Mysore 570020, India. Electronic address: msthakur@cftri.res.in.
authors.forename: Munna Singh
authors.initials: MS
authors.lastname: Thakur
mesh_terms: D015374:Biosensing Techniques; D019187:Cadmium Compounds / Q000737:chemistry*; D004800:Enzymes, Immobilized / Q000378:metabolism; D042845:Laccase / Q000378:metabolism; D057230:Limit of Detection; D059808:Polyphenols / Q000032:analysis* / Q000378:metabolism; D045663:Quantum Dots / Q000737:chemistry*; D029045:Rhus / Q000201:enzymology; D013050:Spectrometry, Fluorescence; D013691:Tellurium / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D004800:Enzymes, Immobilized; D059808:Polyphenols; D042845:Laccase; D013691:Tellurium; C028337:cadmium telluride
keywords: Electron transfer; Laccase; Polyphenols; Quantum dots