Application of Fluorescent Nanocrystals (q-dots) for the Detection of Pathogenic Bacteria by Flow-Cytometry

Fluorescent semiconductor nanocrystals (q-dots) benefit from practical features such as high fluorescence intensity, broad excitation band and emission diameter dependency. These unique spectroscopic characterizations make q-dots excellent candidates for new fluorescent labels in multi-chromatic analysis, such as Flow-Cytometry (FCM). In this work we shall present new possibilities of multi-labeling and multiplex analysis of pathogenic bacteria, by Flow-Cytometry (FCM) analysis and new specific IgG—q-dots conjugates. We have prepared specific conjugates against B. anthracis spores (q-dots585-IgGαB. anthracis and q-dots655-IgGαB.anthracis). These conjugates enabled us to achieve double staining of B. anthracis spores which improve the FCM analysis specificity versus control Bacillus spores. Moreover, multiplexed analysis of B. anthracis spores and Y. pestis bacteria was achieved by using specific antibodies labeled with different q-dots to obtain: q-dots585-IgGαB. anthracis and q-dots655-IgGαY.pestis, each characterized by its own emission peak as a marker. Specific and sensitive multiplex analysis for both pathogens has been achieved, down to 10³ bacteria per ml in the sample.     

Fluorescence Assay Based on Aptamer-Quantum Dot Binding to <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> Spores

A novel assay was developed for the detection of Bacillus thuringiensis (BT) spores. The assay is based on the fluorescence observed after binding an aptamer-quantum dot conjugate to BT spores. The in vitro selection and amplification technique called SELEX (Systematic Evolution of Ligands by EXponential enrichment) was used in order to identify the DNA aptamer sequence specific for BT. The 60 base aptamer was then coupled to fluorescent zinc sulfide-capped, cadmium selenide quantum dots (QD). The assay is semi-quantitative, specific and can detect BT at concentrations of about 1,000 colony forming units/ml.     

A Novel Screening Method for Competitive FRET-Aptamers Applied to <Emphasis Type="Italic">E. coli</Emphasis> Assay Development

A novel high-throughput screening method is described in which a family of DNA aptamers selected against E. coli outer membrane proteins (OMPs) is subjected to PCR in the presence of fluorophore-dUTP conjugates using Deep Vent® exo- polymerase. The fluorophore-doped aptamers and their complementary strands are then heated to render them single-stranded and screened in filter well microtiter plates for fluorescence resonance energy transfer (FRET) assay potential. Using this system, a superior competitive FRET-aptamer designated EcO 4R was identified and the location of its putative binding pocket was determined by individually testing FRET potential in each of the secondary loop structures. By labeling the binding pocket with Alexa Fluor (AF) 647 and binding the aptamer to heavily Black Hole Quencher-3 (BHQ-3)-labeled E. coli bacteria, detection of as few as 30 live unlabeled E. coli per ml was achieved in a competitive displacement FRET assay format. The far red fluorescence emission enables detection in largely blue-green autofluorescent matrices. In addition, the competitive transfer of AF 647-EcO-4R aptamer to unlabeled E. coli cells after a 15 min equilibration period was verified by fluorescence microscopy. The present study also demonstrated that high aptamer affinity is not well correlated with competitive FRET potential.     

Moderate hydrostatic pressure–temperature combinations for inactivation of Bacillus subtilis spores

We report the effect of using moderate hydrostatic pressure, 40–140?MPa, at moderate temperature (38–58°C) to inactivate Bacillus subtilis spores in McIlvaine's citric phosphate buffer at pH 6. We have investigated several parameters: pressure applied, holding time, pressure cycling, and temperature. The kinetics of spore inactivation is reported. The results show that spore inactivation is exponentially proportional to the time the sample is exposed to pressure. Spore germination and inactivation occur at the hydrostatic pressures/temperature combinations we explored. Cycling the pressure while keeping the total time at high pressure constant does not significantly increase spore inactivation. We show that temperature increases spore inactivation at two different rates; a slow rate below 33°C, and at a more rapid rate at higher temperatures. Increasing pressure leads to an increase in spore inactivation below 95?MPa; however, further increases in pressure give a similar rate kill. The time dependence of the effect of pressure is consistent with the first-order model (R²?>?0.9). The thermal resistance values (Z_T) of B. subtilis spores are 30°C, 37°C, and 40°C at 60, 80, 100?MPa. The increase in Z_T value at higher pressures indicates lower temperature sensitivity. The pressure resistance values (Z_P) are 125, 125 and 143?MPa at 38°C, 48°C, and 58°C. These Z_P values are lower than those reported for B. subtilis spores in the literature, which indicates higher sensitivity at pressures less than about 140?MPa. We show that at temperatures <60°C, B. subtilis spores are inactivated at pressures below 100?MPa. This finding could have implications for the design of the sterilization equipment.     

Atomic force microscopy of Bacillus spore surface morphology

Bacillus spore surface morphology was imaged with atomic force microscopy (AFM) to determine if characteristic surface features could be used to distinguish between four closely related species; Bacillus anthracis Sterne strain, Bacillus thuringiensis var. kurstaki, Bacillus cereus strain 569, and Bacillus globigii var. niger. AFM surface height images showed an irregular topography across the curved upper surface of the spores. Phase images showed a superficial grain structure with different levels of phase contrast and significant differences in average surface morphologies among the four species. Although spores of the same species showed similarities, there was significant variability within each species. Overall, AFM revealed that spore surface morphology is rich with information, which can be used to distinguish a sample of about 20 spores from a similar number of spores of closely related species. Statistical analysis of spore morphology from a combination of amplitude and phase images for a small sample allows differentiation between, B. anthracis and its close relatives.     

A Significant Fluorescent Aptamer Sensor Based on Carbon Dots and Graphene Oxide for Highly Selective Detection of Progesterone

In this paper, a fluorescent aptamer sensor was constructed based on the carbon dots (CDs) and graphene oxide (GO). This sensor combines the excellent fluorescence performance of CDs with the high specificity of aptamer, which can detect progesterone (P₄) with high sensitivity and selectivity. In the absence of P₄, the CDs-aptamer system and GO form a fluorescence resonance energy transfer process (FRET), which quenches the fluorescence of the CDs. When P₄ is added, the aptamer specifically binds to it, resulting the fluorescence of the CDs is recovered. At optimal conditions, the fluorescence intensity recovered by the CDs has a linear relationship with the concentration of P₄ in the range of 0.1–120 nM and the detection limit is 3.3?×?10^–11 M. Besides, the sensor has satisfactory detection results of P₄ in milk, indicating that constructed method has enormous potential for application in food safety.

     

Signals of <Emphasis Type="Italic">Z</Emphasis>′ boson in the Bhabha process within the LEP2 data set

The LEP2 data set on the Bhabha process is analyzed with the aim to detect the signals of the heavy virtual Z′ gauge boson. The state interacting with the left-handed Standard Model doublets and called the chiral Z′ is investigated. This particle was introduced already as the low-energy state allowed by the renormalizability. The contribution of the chiral-Z′ state to the Bhabha process is described by two parameters: the coupling to electrons and the Z–Z′ mixing angle. The sign-definite one-parameter observable is proposed to measure the Z′ coupling to the electron current. The one-parameter fit of the data shows no signals of the particle. The alternative two-parameter fit of the differential cross sections is also performed. It also shows no chiral-Z′ signals. The comparisons with other fits are discussed. The text was submitted by the authors in English.     

Fluorescence-based methods for the detection of pressure-induced spore germination and inactivation

The application of high pressure (HP) provides an opportunity for the non-thermal preservation of high-quality foods, whereas highly resistant bacterial endospores play an important role. It is known that the germination of spores can be initiated by the application of HP. Moreover, the resistance properties of spores are highly dependent on their physiological states, which are passed through during the germination. To distinguish between different physiological states and to detect the amount of germinated spores after HP treatments, two fluorescence-based methods were applied. A flow cytometric method using a double staining with SYTO 16 as an indicator for germination and propidium iodide as an indicator for membrane damage was used to detect different physiological states of the spores. During the first step of germination, the spore-specific dipicolinic acid (DPA) is released [P. Setlow, Spore germination, Curr. Opin. Microbiol. 6 (2003), pp. 550–556]. DPA reacts with added terbium to form a distinctive fluorescent complex. After measuring the fluorescence intensity at 270 nm excitation wavelength in a fluorescence spectrophotometer, the amount of germinated spores can be determined. Spores of Bacillus subtilis were treated at pressures from 150 to 600 MPa and temperatures from 37 °C to 60 °C in 0.05 M ACES buffer solution (pH 7) for dwell times of up to 2 h. During the HP treatments, inactivation up to 2log ₁₀ cycles and thermal sensitive populations up to 4log ₁₀ cycles could be detected by plate counts. With an increasing number of thermal sensitive spores, an increased proportion of spores in germinated states was detected by flow cytometry. Also the released amount of DPA increased during the dwell times. Moreover, a clear pressure-temperature-time-dependency was shown by screening different conditions. The fluorescence-based measurement of the released DPA can provide the opportunity of an online monitoring of the germination of spores under HP inside the HP vessel. Implementation can be done using diamond anvil cells, units with inspection glasses or by inserting an optical fiber into the HP vessel. The analytical methods used can help to understand the complex mechanism of germination and inactivation of bacterial spores. Due to its universal, process-independent character, the application of these methods is feasible for established and emerging technologies.     

Using capillary forces to estimate the adhesion strength of Magnaporthe grisea spores on glass

The Magnaporthe grisea is a fungus whose spores strongly adhere to plant leaves, and to solid surfaces in general. In this note, we give an estimate of the adhesion force, F_det, of a spore on a glass surface, in water. F_det is defined as the force to be applied to a spore to pull it out from the surface. In our experiments, spores are detached from the glass in a few milliseconds by means of a capillary force. The latter is provided by a water/air or a water/oil interface, in contact with the spore body. We thus find F_det of the order of 10⁻⁶ N.     

Detection and characterization of single molecules in aqueous solution

Using a confocal microscope with a single-photon avalanche photodiode as detector, we studied photon bursts of single Rhodamine 6G (R6G) and Rhodamin B-zwitterion (RB) molecules in aqueous solution by excitation of the lowest excited singlet stateS ₁ with a frequency-doubled titanium: sapphire laser. Multichannel scaler traces, the fluorescence autocorrelation function and fluorescence decay times determined by time-correlated single-photon counting have been measured simultaneously. The time-resolved fluorescence signals were analyzed with a maximum likelihood estimator. Fluorescence lifetime patterns in steps of 100 ps were generated by convolution with the excitation pulse. The lifetime of theS ₁ state was derived from the Kullback-Leibler minimum discrimination information. We are able to demonstrate for the first time identification of two different single dye molecules via their characteristic fluorescence lifetimes of 1.79 ± 0.33 ns (RB) and 3.79 ± 0.38 ns (R6G) in aqueous solution.Dedicated to Prof. F. P. Schäfer on the occasion of his 65th birthday.On leave from Department of Physics, Mokwon University, Taejon, 301-729, Korea     

Single-oscillator model and determination of optical constants of spray pyrolyzed amorphous SnO<Subscript>2</Subscript> thin films

It has recently been shown that growth of a multilayer structure with one or more delta-layers at high temperature leads to spreading and asymmetrization of the dopant distribution [see, for example, E.F.J. Schubert, Vac. Sci. Technol. A. 8, 2980 (1990), A.M. Nazmul, S. Sugahara, M. Tanaka, J. Crystal Growth 251, 303 (2003); R.C. Newman, M.J. Ashwin, M.R. Fahy, L. Hart, S.N. Holmes, C. Roberts, X. Zhang, Phys. Rev. B 54, 8769 (1996); E.F. Schubert, J.M. Kuo, R.F. Kopf, H.S. Luftman, L.C. Hopkins, N.J. Sauer, J. Appl. Phys. 67, 1969 (1990); P.M. Zagwijn, J.F. van der Veen, E. Vlieg, A.H. Reader, D.J. Gravesteijn, J. Appl. Phys. 78, 4933 (1995); W.S. Hobson, S.J. Pearton, E.F. Schubert, G. Cabaniss, Appl. Phys. Lett. 55, 1546 (1989); Delta Doping of Semiconductors, edited by E.F. Schubert (Cambridge University Press, Cambridge, 1996); Yu.N. Drozdov, N.B. Baidus', B.N. Zvonkov, M.N. Drozdov, O.I. Khrykin, V.I. Shashkin, Semiconductors 37, 194 (2003); E. Skuras, A.R. Long, B. Vogele, M.C. Holland, C.R. Stanley, E.A. Johnson, M. van der Burgt, H. Yaguchi, J. Singleton, Phys. Rev. B 59, 10712 (1999); G. Li, C. Jagadish, Solid-State Electronics 41, 1207 (1997)]. In this work analytical and numerical analysis of dopant dynamics in a delta-doped area of a multilayer structure has been accomplished using Fick's second law. Some reasons for asymmetrization of a delta-dopant distribution are illustrated. The spreading of a delta-layer has been estimated using example materials of a multilayer structure, a delta-layer and an overlayer.     

Effect of supplementary manganese on the sporulation of Bacillus endospores analysed by Raman spectroscopy

It is a common practice in microbiology to induce and accelerate sporulation of spore‐forming bacteria by adding small amounts of divalent manganese to the cultivation medium. By micro‐Raman spectroscopy the effect of supplementary divalent manganese during the growth and sporulation of Bacillus spp. bacteria was studied. The spectral alterations in the Raman spectra of single endospores due to this cultivation parameter comprised slight alterations of the bands attributed to intracellular, abundantly present calcium dipicolinate (CaDPA). Those signals suffered a loss of intensity or partial band broadening because of the appearance of new weak signals next to them. Exclusively in Raman spectra of single B. sphaericuss endospores, the band at 1485 cm⁻¹ vanished. The theoretical spectra of CaDPA and manganese dipicolinate (MnDPA) were calculated and compared with the experimental spectra to prove the hypothesis that, while the overall intracellular DPA content decreased, an intracellular assembly of MnDPA in the endospores might also occur. Band shifts of the COO⁻ vibrations in the salt's spectra as well as in the endospore's spectra, and the decrease of the two CaDPA bands, confirmed this proposal. The appearance of the 1030 cm⁻¹ band in all Bacillus spectra as well as the disappearance of the 1485 cm⁻¹ band in the B. sphaericus spectra still needs to be clarified. With the help of two multivariate chemometric methods, these spectral alterations allowed discrimination between single endospores of different Bacillus strains cultivated on normal nutrient agar (NA) and those grown on NA with MnSO₄ · xH₂O addition. With these investigations, a possible strategy is shown to trace back the cultivation environment of matured single endospores. Utilizing the joint concept of micro‐Raman spectroscopy and chemometric analysis, the differentiation between natively grown endospores and those cultivated in a laboratory with the help of manganous salts as a common sporulation accelerator seems accomplishable. Copyright © 2009 John Wiley & Sons, Ltd.     

CpG oligodeoxyribonucleotides protect mice from <Emphasis Type="Italic">Burkholderia pseudomallei</Emphasis> but not <Emphasis Type="Italic">Francisella tularensis</Emphasis> Schu S4 aerosols

Studies have shown that CpG oligodeoxyribonucleotides (ODN) protect mice from various bacterial pathogens, including Burkholderia pseudomallei and Francisella tularensis live vaccine strain (LVS), when administered before parenteral challenge. Given the potential to develop CpG ODN as a pre-treatment for multiple bacterial biological warfare agents, we examined survival, histopathology, and cytokine data from CpG ODN-treated C57BL/6 mice to determine whether previously-reported protection extended to aerosolized B. pseudomallei 1026b and highly virulent F. tularensis Schu S4 infections. We found that, although CpG ODN protected mice from aerosolized B. pseudomallei challenges, the immunostimulant failed to benefit the animals exposed to F. tularensis Schu S4 aerosols. Our results, which contrast with earlier F. tularensis LVS studies, highlight potential differences in Francisella species pathogenesis and underscore the need to evaluate immunotherapies against human pathogenic species.     

Magnetic properties of ordered nanowires of the quasi-two-dimensional antiferromagnet SpFeMn(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>3</Subscript>

Ordered arrays of nanowires of the photochromic antiferromagnet SpFeMn(C₂O₄)₃ (where Sp is 1-{(1′,3′,3′-trimethyl-6-nitro-5′-chlorospiro[2H-1-benzopyran-2,2′-indolin]-8-yl)methyl}pyridinium) have been fabricated in anodized aluminum oxide pores with diameters of 20 and 200 nm. It has been revealed that the growth of the spin-glass phase with noncollinear ordering of spins in nanowires is suppressed in favor of the uniaxial antiferromagnetic phase. A decrease in the nanowire diameter leads to an increase in the anisotropy of the magnetic resonance spectra. This is associated with the magnetocrystalline anisotropy that considerably exceeds the anisotropy of the nanowire shape.     

High precision localization methods for HZE-particles

For experimental investigations in the field of microdosimetry of heavy ions a high precision localization method for biological objects relative to the path of the penetrating ion is mandatory. New methods are described for corn seeds of Arabidopsis thaliana and spores of Bacillus subtilis. In the latter case the actual penetration point of the particle in the spore layer is determined by an individual microetching technique with an accuracy of about 0.2 μm. This is done after removing the spores from the hit area by “break-through” etching. With the help of reference spores the impact parameter is determined for correlating the biological effects with the physical event. Besides the aspect of water during the track development is described.     

On the Coupling Between Surface Charge and Hydration in Biomembranes: Experiments with 3-Hydroxyflavone Probes

The newly synthesized 3-hydroxyflavone derivative [2-(4-N,N-diethylaminophenyl)-3-hydroxy-6-chromonyl](N,N-dimethyl-octyl) ammonium bromide (F2) together with already used 4-dimethylamino-3-HF (F) are found to be extremely sensitive to the effects of preferential hydration in model solvent system. This property is explored in the study of phospholipid vesicles of different composition made of neutral, cationic, and anionic lipids. We observe an extremely high level of response of both F and F2 fluorescence emission spectra to the surface charge of the vesicles: the N^* form is strongly favored with less positively charged and more negatively charged membrane surface. The strong red-edge effects, which are almost independent of the lipid composition demonstrate the immobility of the probe environment on the time scale of fluorescence emission and suggest the static nature of hydration effects.     

Synthesis and Luminescence Properties of Two Novel Lanthanide (III) Perchlorate Complexes with Bis(benzoylmethyl) Sulfoxide and Benzoic Acid

Two novel ternary rare earth complexes of Tb(III) and Dy(III) perchlorates with bis(benzoylmethyl) sulfoxide (L) and benzoic acid (L′) had been synthesized and characterized by elemental analysis, coordination titration analysis, molar conductivity, IR, TG-DSC, ¹HNMR and UV spectra. The results indicated that the composition of these complexes was REL₅L′(ClO₄)₂·nH₂O (RE= Tb(III), Dy(III); L=C₆H₅COCH₂SOCH₂COC₆H₅, L′=C₆H₅COO; n = 6,8). The fluorescence spectra illustrated that the ternary rare earth complexes presented stronger fluorescence intensities, longer lifetimes and higher fluorescence quantum efficiencies than the binary rare earth complexes REL₅·(ClO₄)₃·2H₂O. After the introduction of the second ligand benzoic acid group, the relative fluorescence emission intensities and fluorescence lifetimes of the ternary complexes REL₅L′(ClO₄)₂·nH₂O (RE= Tb(III), Dy(III)) enhanced more obviously than the binary complexes. This indicated that the presence of both organic ligands bis(benzoylmethyl) sulfoxide and the second ligand benzoic acid could sensitize fluorescence intensities of rare earth ions, and the introduction of benzoic acid group was resulted in the enhancement of the fluorescence properties of the ternary rare earth complexes. The phosphorescence spectra were also discussed.     

Rational Design of Novel Benzimidazole-Based Sensor Molecules that Display Positive and Negative Fluorescence Responses to Anions

Two novel and neutral benzimidazole derivatives-based anion receptors bearing a 1,10-phenanthroline fluorophore, N,N′-di-(2′-benzimidazolyl-methylene)-1, 10-phenanthroline-2,9-diamide (1) and N,N′-di-[2′-(benzimidazolyl-2′-) ethyl-]-1,10-phenanthroline-2,9-diamide (2), which exhibited turn-on and turn-off fluorescence responses to various anions, were rationally designed and synthesized and their fluorescent response toward anions was investigated in DMSO solution. In the process of anions binding, there were two different fluorescent responses in presence of anions: a quenching of the fluorescence emission for F^- and AcO^- and an enhancement of the fluorescence emission for Cl⁻, Br⁻ and I⁻. Two different luminescent mechanisms of the receptors 1 and 2 resulting from various anions were exploited to rationalize quenching and enhancement of the fluorescence emission: a photo-induced electronic transfer mechanism (PET) and the increase of the rigidity of the host molecules, respectively. In particular, chloride could be recognized selectively from the anions tested according to changes of fluorescence spectrum. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The Susceptibility of Non-UV Fluorescent Membrane Dyes to Dynamical Properties of Lipid Membranes

Fluorescence spectroscopy and microscopy are powerful techniques to detect dynamic properties in artificial and natural lipid membrane systems. Unfortunately, most fluorescent dyes that sense dynamically relevant membrane parameters are UV sensitive. Their major disadvantage is a high susceptibility to fluorescence bleaching. Additionally, the risk for hazardous damages in biological components generally increases with decreasing excitation wavelength. Therefore the use of non-UV–sensitive membrane dyes would provide significant advantage, particularly for applications in fluorescence microscopy, which usually implies high local excitation intensities. We applied steady-state fluorescence spectroscopy techniques to several UV and non-UV membrane dyes to detect and compare dynamically relevant excitation and emission characteristics. Small unilamellar liposomes (composed of egg yolk phosphatidylcholine) served as a model system for biological membranes. The dynamic properties of the membranes were varied by two independent parameters: the intrinsic cholesterol content (0–50 mol%) and temperature (10–50°C). We tested four non-UV–sensitive membrane dyes: 9-diethylamino-5H-benzophenoxazine-5-one (Nile Red), 4-(dicyanovinyl)julolidine (DCVJ), N-(3-triethylammoniumpropyl)-4-(4-(dibutylamino)styryl) pyridinium dibromide (FM 4-64), and 1,1-dioctadecyl-3,3,3,3-tetramethylindocarbocyanine perchlorate (DiIC₁₈). We also tested three derivatives of DiIC₁₈: DiIC₁₆ and DiIC₁₂ differ in acyl chain length and Fast-DiIC₁₈ provides double bonds between hydrocarbon atoms. The spectral results were compared to established fluorescence characteristics of four UV membrane dyes: the anisotropy of 1-6-phenyl-1,3,5,-hexatrien (DPH), two derivatives of DPH (TMA-DPH and COO^–-DHP), and the generalized polarization of 6-dodecanoyl-2-dimethyl-aminonaphthalene (Laurdan). Our results indicate that the tested non-UV dyes do not reveal dynamically relevant membrane parameters in a direct manner. However, spectral characteristics make DiIC₁₈, Nile Red, and DCVJ promising probes for the microscopic detection of lateral lipid organization, an indirect indicator of membrane dynamics. In particular, DiIC₁₈ showed very selective shifts in the emission spectra at defined temperatures and cholesterol contents that have not been reported elsewhere.     

适配体传感法快速测定啤酒中赭曲霉毒素A

应用自组装方式,构建了金纳米粒子/核酸适体/氨基碳量子点荧光传感赭曲霉毒素A高灵敏检测方法。在pH 3.0酒石酸-HCl缓冲溶液中,巯基修饰的赭曲霉毒素A核酸适体在金纳米粒子表面自组装,形成金纳米粒子/核酸适体复合物,再在pH 7.0的磷酸盐缓冲溶液中,氨基碳量子点在金纳米粒子/核酸适体复合物上自组装,形成金纳米粒子/核酸适体/氨基碳量子点复合物荧光传感检测体系。金纳米粒子的摩尔吸光系数大、能带宽使其具有强烈的荧光猝灭功能,氨基碳量子点形成金纳米粒子/核酸适体/氨基碳量子点后发生荧光猝灭, 此时体系的荧光为背景荧光,其强度记为F₀;由于金纳米粒子/核酸适体/氨基碳量子点复合物荧光传感检测体系中核酸适体对赭曲霉毒素A具有特异性识别与结合功能,向金纳米粒子/核酸适体/氨基碳量子点复合物荧光传感检测体系溶液中加入赭曲霉毒素A后,赭曲霉毒素A则与复合物中核酸适体立即发生特异性结合并释放出氨基碳量子点,体系荧光恢复,其荧光强度记为F。依据体系荧光强度的变化(F-F₀)与赭曲霉毒素A浓度之间的关系,建立赭曲霉毒素A核酸适体荧光传感检测方法。研究了金纳米粒子和核酸适体摩尔比、孵化时间、pH等因素对传感器性能的影响,确定了最优条件为金纳米粒子∶核酸适体t为1∶190、孵化时间为6 min、pH 7.0时;在最优条件下,赭曲霉毒素A浓度在0.005～1.00 ng·mL-1范围与体系荧光强度变化呈良好线性关系,线性回归方程为：F-F₀=6.499+211.6c(c为赭曲霉毒素A的浓度,单位：ng·mL-1),相关系数r为0.995 5,按3倍标准差与工作曲线的斜率的比值(3σ/k)计算,得检测限为3 pg·mL-1。在实际样品中的回收率在93.3%～108.9%,相对标准偏差小于5%,能满足啤酒样品中赭曲霉毒素A快速检测要求。对13个市售啤酒样品进行检测,其中6个样品检出赭曲霉毒素A,污染率为46.15%。受污染样品的赭曲霉毒素A含量在0.008～0.63 ng·mL-1范围。该荧光传感法检测赭曲霉毒素A具有灵敏性好、特异性高、常见真菌毒素无干扰、方法简单、快速,便于大众化推广应用的优点。