ABSTRACT
An optical aptasensor was developed for ultrasensitive detection of ochratoxin A (OTA) based on hybridization chain reaction (HCR) amplification strategy and fluorescent perylene probe (PAPDI)/DNA composites. Dendritic DNA concatamers were synthesized by HCR strategy and modified on magnetic nanoparticles through aptamer as medium. A large amount of PAPDI probe aggregated under the induction of DNA concatamers and caused fluorescence quenching. In the presence of OTA, the PAPDI/DNA composites were released from magnetic nanoparticles due to the strong affinity between aptamer and OTA. In ethanol, PAPDI monomers disaggregated and produced strong fluorescence. The present method displays excellent sensitivity and selectivity towards OTA.
Subject(s)
Aptamers, Nucleotide/chemistry , Biosensing Techniques/methods , Fluorescent Dyes/chemistry , Mycotoxins/analysis , Ochratoxins/analysis , Perylene/chemistry , Food Analysis/methods , Limit of Detection , Nucleic Acid Hybridization/methods , Spectrometry, Fluorescence/methods , Zea mays/microbiologyABSTRACT
Novel fluorescent nitrogen-doped carbon dots (N,C-dots) were synthesized and assembled on aptamer modified gold nanoparticles (Aptamer/AuNPs) for the super sensitive detection of aflatoxin B1 (AFB1). Positively charged N,C-dots were synthesized by the hydrothermal treatment of pancreatin. The prepared N,C-dots were assembled on aptamer/AuNPs by electrostatic interactions. The fluorescence of the N,C-dots was efficiently quenched. When AFB1 was added to the assay solution, specific interactions between AFB1 and the aptamer caused release of the N,C-dots. The fluorescence of the N,C-dots recovered and the intensity increase could be used to calculate the amount of AFB1 added. The assay exhibits super-high sensitivity with a detection limit of 5 pg/mL (16 pM) and a wide range of linear response of 5 pg/mL to 2.00 ng/mL. A novel aptasensor is thus successfully constructed, it provides an efficient way for sensitive AFB1 sensing as well as a new technique for aptamer based novel sensor construction.
Subject(s)
Aflatoxin B1/isolation & purification , Aptamers, Nucleotide/chemistry , Biosensing Techniques/methods , Electrochemical Techniques/methods , Aflatoxin B1/chemistry , Arachis/chemistry , Carbon/chemistry , Fluorescence , Gold/chemistry , Limit of Detection , Metal Nanoparticles/chemistry , Nitrogen/chemistry , Zea mays/chemistryABSTRACT
In this work, an enhanced electrochemiluminescence (ECL) sensor based on gold nanoflower@graphitic carbon nitride polymer nanosheet-polyaniline hybrids (AuNF@g-C3N4-PANI) was prepared for the detection of dapamine (DA). First, the bulk g-C3N4 was prepared through polymerizing melamine under 600 °C. And then the g-C3N4 nanosheet was obtained by ultrasonication-assisted liquid exfoliation of bulk g-C3N4. Finally, polyaniline (PANI) and gold nanoflowers (AuNFs) were successively formed on the g-C3N4 nanosheet through an in situ synthesis method. The resulting AuNF@g-C3N4-PANI hybrids were modified onto the surface of glassy carbon electrode to achieve a sensor (AuNF@g-C3N4-PANI/GCE) for detecting dopamine. Under the optimal conditions, the ECL signal increased linearly with the concentration of dopamine. The linear range of 5.0 × 10(-9) to 1.6 × 10(-6) M was obtained, while the detection limit was 1.7 × 10(-9) M. The prepared sensor exhibited a low detection limit and high sensitivity for the determination of dopamine. The combination of g-C3N4 nanosheet, PANI and AuNF would provide a new opportunity for the ECL sensor.
Subject(s)
Aniline Compounds/chemistry , Dopamine Agents/analysis , Dopamine/analysis , Electrochemical Techniques/methods , Gold/chemistry , Graphite/chemistry , Nitriles/chemistry , Limit of Detection , Luminescent Measurements/methods , Nanostructures/chemistry , Nanostructures/ultrastructureABSTRACT
This paper described a novel strategy for the construction of an electrogenerated chemiluminescence (ECL) sensor based on gold nanoparticles@C60 (AuNPs@C60) hybrid for detecting phenolic compounds. First, C60 was functionalized with l-cysteine. Subsequently, with C60 as the core, gold nanoparticles (AuNPs) are synthesized and grown through an in situ reduction method in the presence of ascorbic acid (AA). The resulted flowerlike AuNPs@C60 nanoparticles were modified onto the glassy carbon electrode to achieve the sensor (AuNPs@C60/GCE). Here, l-cysteine not only can improve the biocompatibility and hydrophilicity of C60 but also can enhance the electrogenerated chemiluminescence (ECL) of peroxydisulfate system. Furthermore, both AuNPs and C60 are also beneficial to the ECL of the peroxydisulfate system. Due to the combination of l-cysteine, AuNPs and C60, the proposed ECL sensor exhibited an excellent analytical performance. Under an optimum condition, the ECL intensity increased linearly with phenolic compounds. The linear ranges of 6.2 × 10(-8)-1.2 × 10(-4)M, 5.0 × 10(-8)-1.1 × 10(-4)M and 5.0 × 10(-8)-1.1 × 10(-4)M were obtained for catechol (CC), hydroquinone (HQ) and p-cresol (PC), respectively, and the detection limits were 2.1 × 10(-8)M, 1.5 × 10(-8)M and 1.7 × 10(-8)M, respectively. The AuNPs@C60 hybrid might hold a new opportunity to develop an ECL sensor.
