Label-free fluorescence detection of melamine with a truncated aptamer.

The 2008 Chinese milk scandal caused by the adulteration of melamine encouraged the public to pay attention to melamine detection in milk products and other food stuffs. To allow simple and rapid detection of melamine, we previously isolated an 88 nt melamine aptamer (called Rd29C33) using the structure-switching SELEX. However, this 88 nt oligonucleotide is costly to synthesize, and may also complicate the rational design of biosensors for melamine detection. To overcome this obstacle, we truncated Rd29C33 at several sites, and a 34 nt Rd29C33-T7 melamine aptamer was finally found to show comparable binding affinity and better selectivity to melamine compared to the original 88 nt Rd29C33. Furthermore, a label-free bioassay method for melamine detection was designed by using Rd29C33-T7 and thiazole orange (TO). The addition of melamine to a mixture of Rd29C33-T7 and TO caused the release of TO from Rd29C33-T7, resulting in a decrease of the fluorescence intensity of the solution. A detection limit of 0.12 μM for melamine was achieved using this label-free method. Good recovery ranging from 82.6% to 97.2% for melamine detection in whole milk samples suggested the promise of this bioassay method for application in monitoring melamine in real food stuffs.

[1]  Shuiping Yang,et al.  Detection of melamine in milk products by surface desorption atmospheric pressure chemical ionization mass spectrometry. , 2009, Analytical chemistry.

[2]  J. McNamara,et al.  Rational truncation of an RNA aptamer to prostate-specific membrane antigen using computational structural modeling. , 2011, Nucleic acid therapeutics.

[3]  Amanda Deering,et al.  Melamine detection in infant formula powder using near- and mid-infrared spectroscopy. , 2009, Journal of agricultural and food chemistry.

[4]  L. Gold,et al.  Systematic evolution of ligands by exponential enrichment: RNA ligands to bacteriophage T4 DNA polymerase. , 1990, Science.

[5]  Tatsuro Endo,et al.  Label-free detection of peptide nucleic acid-DNA hybridization using localized surface plasmon resonance based optical biosensor. , 2005, Analytical chemistry.

[6]  Yan Zhang,et al.  Highly sensitive and rapid detection of melamine in milk products by planar waveguide fluorescence immunosensor (PWFI) , 2014 .

[7]  Lehui Lu,et al.  Hydrogen-bonding recognition-induced color change of gold nanoparticles for visual detection of melamine in raw milk and infant formula. , 2009, Journal of the American Chemical Society.

[8]  J. Szostak,et al.  In vitro selection of RNA molecules that bind specific ligands , 1990, Nature.

[9]  Chunyan Sun,et al.  Visual detection of melamine in raw milk by label-free silver nanoparticles , 2012 .

[10]  D. Boger,et al.  Thiazole orange as the fluorescent intercalator in a high resolution fid assay for determining DNA binding affinity and sequence selectivity of small molecules. , 2001, Bioorganic & medicinal chemistry.

[11]  S. Ehling,et al.  High-performance liquid chromatographic method for the simultaneous detection of the adulteration of cereal flours with melamine and related triazine by-products ammeline, ammelide, and cyanuric acid , 2007, Food additives and contaminants.

[12]  Xiaohong Zhou,et al.  Label-free detection of kanamycin based on a G-quadruplex DNA aptamer-based fluorescent intercalator displacement assay , 2015, Scientific Reports.

[13]  R. Stoltenburg,et al.  SELEX--a (r)evolutionary method to generate high-affinity nucleic acid ligands. , 2007, Biomolecular engineering.

[14]  N. Schirle,et al.  Screening helix-threading peptides for RNA binding using a thiazole orange displacement assay. , 2008, Bioorganic & medicinal chemistry.

[15]  P. Bolton,et al.  Fluorescent dyes specific for quadruplex DNA. , 1998, Nucleic acids research.

[16]  S. Parveen,et al.  Oligonucleotide-stabilized fluorescent silver nanoclusters for turn-on detection of melamine. , 2012, Biosensors & bioelectronics.

[17]  M. Kubista,et al.  The interactions between the fluorescent dye thiazole orange and DNA. , 1998, Biopolymers.

[18]  Tao Li,et al.  Parallel G-quadruplex-specific fluorescent probe for monitoring DNA structural changes and label-free detection of potassium ion. , 2010, Analytical chemistry.

[19]  N. Sugimoto,et al.  Characterization of structure and stability of long telomeric DNA G-quadruplexes. , 2006, Journal of the American Chemical Society.

[20]  T. Scheper,et al.  Identification of the target binding site of ethanolamine-binding aptamers and its exploitation for ethanolamine detection. , 2015, Analytical chemistry.

[21]  M. Teulade‐Fichou,et al.  Development of a fluorescent intercalator displacement assay (G4-FID) for establishing quadruplex-DNA affinity and selectivity of putative ligands. , 2006, Bioorganic & medicinal chemistry letters.

[22]  Razvan Nutiu,et al.  In vitro selection of structure-switching signaling aptamers. , 2005, Angewandte Chemie.

[23]  Zhuang Li,et al.  Label-free turn-on fluorescent detection of melamine based on the anti-quenching ability of Hg 2+ to gold nanoclusters. , 2014, Biosensors & bioelectronics.

[24]  Michael Zuker,et al.  Mfold web server for nucleic acid folding and hybridization prediction , 2003, Nucleic Acids Res..

[25]  Juewen Liu,et al.  Functional nucleic acid sensors. , 2009, Chemical reviews.

[26]  S. Jayasena.  Aptamers: an emerging class of molecules that rival antibodies in diagnostics. , 1999, Clinical chemistry.

[27]  M. Gu,et al.  An ultra-sensitive colorimetric detection of tetracyclines using the shortest aptamer with highly enhanced affinity. , 2014, Chemical communications.

[28]  Yi Lu,et al.  Using personal glucose meters and functional DNA sensors to quantify a variety of analytical targets. , 2011, Nature chemistry.

[29]  Yi Lu,et al.  Portable Detection of Melamine in Milk Using a Personal Glucose Meter Based on an in Vitro Selected Structure-Switching Aptamer. , 2015, Analytical chemistry.