TiO2 Nanolayer-Enhanced Fluorescence for Simultaneous Multiplex

Research Article www.acsami.org

Cite This: ACS Appl. Mater. Interfaces 2018, 10, 14447−14453

TiO2 Nanolayer-Enhanced Fluorescence for Simultaneous Multiplex Mycotoxin Detection by Aptamer Microarrays on a Porous Silicon Surface Rui Liu,†,§ Wei Li,‡,§ Tingting Cai,†,§ Yang Deng,† Zhi Ding,† Yan Liu,† Xuerui Zhu,† Xin Wang,† Jie Liu,† Baowen Liang,† Tiesong Zheng,† and Jianlin Li*,† †

Department of Food Science and Engineering, Nanjing Normal University, Nanjing 210024, China Department of Electronic and Electrical Engineering, The University of Sheffield, Sheffield S3 7HQ, U.K.

Downloaded via UNIV OF NEW ENGLAND on July 10, 2018 at 17:39:33 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.

‡

S Supporting Information *

ABSTRACT: A new aptamer microarray method on the TiO 2−porous silicon (PSi) surface was developed to simultaneously screen multiplex mycotoxins. The TiO 2 nanolayer on the surface of PSi can enhance the fluorescence intensity 14 times than that of the thermally oxidized PSi. The aptamer fluorescence signal recovery principle was performed on the TiO2−PSi surface by hybridization duplex strand DNA from the mycotoxin aptamer and antiaptamer, respectively, labeled with fluorescence dye and quencher. The aptamer microarray can simultaneously screen for multiplex mycotoxins with a dynamic linear detection range of 0.1−10 ng/mL for ochratoxin A (OTA), 0.01−10 ng/mL for aflatoxins B1 (AFB1), and 0.001−10 ng/mL for fumonisin B1 (FB1) and limits of detection of 15.4, 1.48, and 0.21 pg/mL for OTA, AFB1, and FB1, respectively. The newly developed method shows good specificity and recovery rates. This method can provide a simple, sensitive, and cost-efficient platform for simultaneous screening of multiplex mycotoxins and can be easily expanded to the other aptamer-based protocol. KEYWORDS: multiplex mycotoxins, aptamer, porous silicon, titanium dioxide, fluorescence microarrays, simultaneous detection

■

INTRODUCTION Mycotoxins are low-molecular-weight secondary metabolites produced by filamentous fungi species, mainly Aspergillus spp., Penicillium spp., and Fusarium spp., growing on agricultural crops in fields and during storage.1,2 Cereal samples, such as wheat, corn, rice, peanuts, sorghum, and barley, are often contaminated by mycotoxins. Hundreds of mycotoxins with different chemical structures have been identified. They can evoke a broad range of toxic properties including carcinogenicity, neurotoxicity, reproductive, and developmental toxicity to human beings and animals.3 To protect the health of consumers, very strict limits of mycotoxins in cereals and feeds have been set in many countries and regions. For example, maximum levels of 4 μg/kg for the sum of aflatoxins B1 (AFB1), B2, G1, and G2; 2 μg/kg for AFB1; and 5 μg/kg for ochratoxin A (OTA) in cereals and all products derived from cereals and 400−4000 μg/kg for fumonisin B1 (FB1) are allowed by European Commission.4 The co-occurrence of mycotoxins has been always found in the same sample because one sample can be infected by different fungi species and one fungus can simultaneously produce several kinds of mycotoxins. This co-occurrence of multiplex mycotoxins shows the additional or synergistic toxic effects.5 In addition, some mycotoxins are stable to heat. Thus, © 2018 American Chemical Society

they are hard to remove once they enter into the food chains. Therefore, the priority measure to prevent mycotoxins from contaminating food chains is to develop simple, cost-efficient, and sensitive detection techniques for multiplex mycotoxins. Compared with each mycotoxin detection in one run, the simultaneous detection method for multiplex mycotoxins has obvious advantages in cost and speed of detection. For the multiplex mycotoxin detection, high-performance liquid chromatography−mass spectrometry (HPLC−MS/ MS),5,6 gas chromatography−MS,7 lateral flow methods,1,8,9 solid-phase microarray,10,11 suspension arrays,12,13 and labelfree optical techniques14,15 have been developed for simultaneous detection of multiplex mycotoxins. Although chromatography methods show high sensitivity, accuracy, and good reproducibility for multiplex mycotoxins, they are quite expensive and require the complicated pretreatment of samples and skilled personnels. Most of the solid-phase microarray techniques, suspension arrays, and label-free optical techniques for multiplex mycotoxin detection are based on the principle of immunoassay and require specific antibodies and artificial Received: January 25, 2018 Accepted: April 6, 2018 Published: April 6, 2018 14447

DOI: 10.1021/acsami.8b01431 ACS Appl. Mater. Interfaces 2018, 10, 14447−14453

Research Article

ACS Applied Materials & Interfaces

Cereal samples including rice, corn, and wheat samples were purchased from supermarket in local. Preparation of PSi, Thermally Oxidized PSi, and TiO2−PSi. PSi, thermally oxidized PSi, and TiO2−PSi were prepared according to ref 37. Briefly, P++-type silicon wafers (boron-doped, 0.0008−0.0012 Ω cm resistivity) were etched by a Teflon etch cell and a platinum counter electrode. The wafer (1.3 cm × 1.3 cm) was immersed in a solution 3:1 (v/v) H2SO4/H2O2 for 30 min and then washed with double distilled water three times and dried with a stream of nitrogen. The wafer was etched with 3:1 (v/v) mixture of aqueous 48% HF and absolute ethanol. The wafer was first cleaned by etching a sacrificial layer of PSi at a current density of 100 mA/cm2 for 20 s in dark. The sacrificial layer was removed with an aqueous solution of 1 M NaOH for 1 min. The wafer was washed with ethanol and dried with a stream of nitrogen. The wafer was etched at a certain current density for 20 s and washed with absolute ethanol and then dried with a stream of nitrogen. The PSi sample was thermally oxidized in a tube furnace at 500 °C for 1 h. TiO2 sol−gel was prepared with a solution of 5:30:1 titanium butoxide/ethanol/triethanolamine (v/v). TiO2 sol−gel (100 μL) was deposited on the surface of the thermally oxidized PSi (PSiO2) by spin-coating at 10g for 20 s. The sample was calcined in a tube furnace at 500 °C for 1 h. The deposition process was repeated three times on each sample. Characterization of the TiO2−PSi Surface. The spectra of white light reflected from the wafer film were obtained with a Y type fiber and spectrograph in 0.1 M, pH 7.4 phosphate buffer solution (PBS) according to the previous description.36,37 The scanning electron microscopy images of the samples were taken with a FEI XL30 microscope equipped with a field emission gun and through-the-lens detector at an accelerating voltage of 5 kV. The photographs of the samples were taken with a common digital camera. The characterizations of the TiO2−PSi surface are shown in Figure S1. Modification of the TiO2−PSi Surface. TiO2−PSi is immersed in 5% GPTMS toluene solution at room temperature for 12 h and then washed with toluene, absolute ethanol, and double stilled water. Immobilization of Oligonucleotides on the TiO2−PSi Surface and Detection of Fluorescence Intensity. The certain concentrations of aptamers and antiaptamers of OTA, AFB1, and FB1 in the binding buffer solution (0.01 mol/L, pH 8.0 Tris-HCl, 120 mmol/L NaCl, 20 mmol/L CaCl2, 5 mmol/L KCl, 20 mmol/L MgCl2) were heated in a water bath at 88 °C for 5 min. The equal volume of aptamers and antiaptamers was mixed and incubated at 25 °C for 2 h. The mixture (0.2 μL) was dropped on the surface of the TiO2−PSi surface modified with GPTMS. The sample was put in a hybridization chamber at 37 °C for 12 h. Then, the sample was washed with PBS, PBST, and Tris-HCl solution three times. Finally, the sample was dried with nitrogen. The fluorescence intensity (I1) of the sample was obtained by LuxScan 10k (Captial Bio Crop., China) at an excitation wavelength of 550 nm and an emission wavelength of 570 nm. To investigate the stability of fluorescent signals on the TiO2−PSi surface, the fluorescent intensities of samples were recorded each 20 min for successive 100 min. The stability of fluorescent signals was calculated according to the percentage between the fluorescence value of different times and the initial fluorescence value. The threedimensional (3D) image of the fluorescence sample was taken by confocal laser scanning microscopy (Nikon, Ti-E-A1R) at an excitation wavelength of 550 nm. Multiplex Detection for OTA, AFB1, and FB1. Hundred microliters of a series of concentrations of OTA, AFB1, and FB1 standard substances or real sample extraction was added dropwise on the surface of TiO2−PSi immobilized with the hybridized aptamers of OTA, AFB1, and FB1. The samples were incubated at 37 °C for 12 h, then respectively washed with PBS, PBST, and Tris-HCl solution three times, and dried with nitrogen. The fluorescence intensity (I2) of the wafer was obtained by LuxScan 10k at an excitation wavelength of 550 nm and an emission wavelength of 570 nm. The calibration curves for the three mycotoxins were established through fluorescent values of ΔI = I2 − I1 as vertical axis and the different concentrations of mycotoxins as horizontal axis.

antigens which have a complex preparation process. In addition, the one-dimensional (1D) glass plane substrate is often used as a probe molecule carrier for the common solid-phase microarray techniques, which limits the detection sensitivity because of its low accommodation capability of probe molecules.16,17 Porous silicon (PSi) is a powerful platform for biosensor because of its cost efficiency, versatile fabrication, easy modification, large surface area, and good biological compatibility.18,19 PSi has been used for assaying small molecules,16,17,20,21 heavy metals,22 proteins,23−28 DNAs,18,29 virus,30 and cells.31−34 However, the fresh surface of PSi is unstable, which has greatly prevented it from being applied in practice.35 Although chemical modifications of Si−O and Si−C bond methods have been used to stabilize the surfaces of PSi, the surfaces are still subject to various degrees of corrosion and dissolution under physiological or higher pH conditions.36 Recently, we have prepared the stable surfaces of PSi by spinning sol−gel TiO2 on the surfaces of PSi.37 The TiO2−PSi surface has been demonstrated to be stable in the pH 2−12 buffer solutions.37 In this work, we reported a stable, sensitive aptamer microarray for simultaneous multiplex mycotoxin assay using the TiO2−PSi surface. We found that the nano-TiO2 layer on the surface of PSi can enhance the fluorescence intensity 14 times than that of thermally oxidized PSi. Aptamers, a type of single-stranded oligonucleotides, can bind to target molecules with high affinity and selectivity.38 Aptamers are considered promising recognition probes alternative to antibodies because of their distinct advantages over antibodies in easier synthesis, modification and immobilization, better stability, and higher reproducibility.39 Aptamers for mycotoxins (such as AFB1, OTA, and FB1) have been selected by the systematic evolution of ligands by exponential enrichment process and used to detect mycotoxins.40 However, the reports on simultaneous multiplex mycotoxins still are few. This work will provide a new platform for simultaneous multiplex mycotoxin assays. In addition, the developed method is easily expanded to other aptamer assay system.

■

EXPERIMENTAL SECTION

Experimental Materials. AFB1, OTA, ochratoxin B (OTB), and FB1 standard substance were purchased from Pribolab (Singapore). (3Aminopropyl)triethoxysilane, (3-glycidyloxypropyl) trimethoxysilane (GPTMS), and tris(hydroxymethyl)aminomethane (Tris) were purchased from Sigma-Aldrich (Shanghai, China). Absolute ethanol, sodium hydroxide, sulfuric acid, and hydrogen peroxide were obtained from Nanjing Chemistry Reagents Co., Ltd. (Nanjing, China). Silicon wafers (0.0008−0.0012 Ω cm resistivity, polished on the (100) face, Bdoped) were obtained from Siltronix Co. (Archamps, France). Hydrofluoric acid (48%) was purchased from Tokyo Chemical Industry Co., Ltd. (Tokyo, Japan). AFB1, FB1, and OTA ELISA kits were purchased from Hongdu Biotech Co., Ltd (Shandong, China). Aptamers and antiaptamers for AFB1, FB1, and OTA were as follows: AFB1-aptamer, 5′-NH2−(CH2)6-AGT TGG GCA CGT GTT GTC TCT CTG TGT CTC GTG CCC TTC GCT AGG CCC ACA-Cy33′, AFB1 antiaptamer, 5′-BHQ2-TGT GGG CCT AGC GA-3′; FB1aptamer, 5′-NH2−(CH2)6-TCT AAC GTG AAT GAT AGA TTA ACT TAT TCG ACC ATA CAC GTC TGC ATT ACC TTA TTC GAC CAT ATT CCA TTA CGC TAA TTA ACT TAT TCG ACC ATA-Cy3-3′, FB1 antiaptamer, 5′-BHQ2-TAT GGT CGA ATA AGT TAA-3′; and OTA-aptamer, 5′-NH2−(CH2)6-GAT CGG GTG TGG GTG GCG TAA AGG GAG CAT CGG ACA-Cy3-3′, OTA antiaptamer, 5′-BHQ2-TGT CCG ATG C-3′. These aptamers and antiaptamers were synthesized and modified by Sangon Biotech Co., Ltd. (Shanghai, China). 14448


Research Article


Figure 1. Fluorescence characteristics of PSiO2 and TiO2−PSi surfaces. The images of fluorescence scanning of the aptamer labeled with Cy3 immobilized on the surface of TiO2−PSi (a) and the surface of thermally oxidized PSi (b); the fluorescence intensities and background fluorescence intensities for the aptamer labeled with Cy3 immobilized on the surfaces of TiO2−PSi and thermally oxidized PSi (c); the fluorescence stability of the aptamer labeled with Cy3 immobilized on the surface of TiO2−PSi as time (d); and the 3D image of the fluorescence sample (e). Specificity for the Multiplex Mycotoxin Assay. The specificity for the multiplex mycotoxin assay was measured among OTA, AFB1, FB1, and OTB. OTA, OTB, AFB1, and FB1 standard substances (100 μL, 1 ng/mL) were added dropwise on the surfaces of the wafers immobilized with the hybridized aptamers of OTA, AFB1, and FB1. The incubations between mycotoxins and aptamers were the same as the above detection process. The fluorescence intensities of the samples were taken according to the above method. Application of the Developed Method in the Real Samples. The cereal samples including rice, wheat, and corn were pretreated according to our previous method.12 In brief, these samples were ground by a high-speed disintegrator. The samples whose particle size was less than 1 mm were used as the spiked samples. The cereal sample (5 g) was put in a 100 mL conical flask with a cover. Different concentrations of mycotoxin standard substances in 100% methanol were added into the sample and then completely mixed with the samples. These spiked samples were put in a fume hood overnight to evaporate the solvent. NaCl (1 g) and 25 mL of 80% methanol−water (v/v) were added to the sample and completely mixed. The sample was homogenized by a homogenizer (FJ-200 Shanghai Specimen Model Factory, Shanghai, China) at 820g for 1 min. The sample was shaken at 5g at 25 °C for 30 min and filtrated with a Whatman filter paper. The filtrate was passed through a 0.45 μm filter member. The filtrate was collected for mycotoxin detection. The control samples were extracted under the same conditions. The samples were measured according to the above method. The traditional ELISA for the samples was performed according to ELISA kit instructions. Data Analysis. These data were analyzed with Origin 9.3 software. The average value and standard deviation for each sample were calculated from no less than four samples.

Safety Precaution. The researchers should avoid direct contact with mycotoxins and laboratory contamination. The sample pretreatment, mycotoxin extraction, and detection should be carried out in a fume hood. Experimenters should equip with laboratory coat, safety glasses, gloves, and mouth-muffle.

■

RESULTS AND DISCUSSION Enhanced Fluorescence Characteristics of the TiO2− PSi Surface. An aptamer (0.2 μL, 16 μmol/L; for OTA) Scheme 1. Principle of Simultaneous Multiplex Mycotoxin Assay on the TiO2−PSi Surface

labeled with Cy3 was immobilized on the surfaces of PSiO2 and TiO2−PSi modified with GPTMS. The fluorescence intensities of samples and control samples were detected by the fluorescence scanner. Figure 1a,b shows that the fluorescence 14449


Research Article


Figure 2. Calibration curves for multiplex mycotoxin assay. The relationship between the fluorescence intensities and the concentrations of mycotoxins [(a−c) for OTA, AFB1, and FB1, respectively]; the detection linear ranges for mycotoxins [(d−f) for OTA, AFB1, and FB1, respectively].

emission intensity of the dye has been increased because the polar TiO2 surface enhances the delocalization of the π electrons and lowers the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels of the dye.41 Figure 1d shows the stability of the fluorescence signal on the TiO2−PSi surface. From 0 to 100 min, the fluorescence value decreased by 11.6%. The fluorescence decrease may be attributed to the self-quench of the fluorescence dye and many times excitation during detection. Figure 1e shows that the 3D confocal laser scanning image of the fluorescence aptamer molecules immobilized on the surface of TiO2−PSi. The result indicates that the aptamer is bound to both on the inner pore wall and the outer surface of TiO2−PSi. Compared with the general microarray plane carrier, the porous structure carrier can accommodate more probe molecules both on its internal and outer surface, which is beneficial to the detection sensitivity. Principle of Simultaneous Multiplex Mycotoxin Assay on the TiO2−PSi Surface. The principle of simultaneous multiplex mycotoxin assay on the TiO2 surface is shown in Scheme 1. PSi was prepared by the electrochemistry etching method. After PSi has been thermally oxidized in a tube furnace in air at 500 °C for 1 h, PSiO2 has been stabilized with the TiO2 sol−gel method.37 Aptamers of OTA, AFB1, and FB1 and their antiaptamers (partial complementary strands) have been hybridized in the test tube. The different positions of the TiO2−PSi surface are used to encode the different mycotoxin

Figure 3. Specificity for multiplex mycotoxin assay.

intensity of the sample on the TiO2−PSi surface is remarkably higher than that on the thermally oxidized PSi surface. Figure 1c displays that the fluorescence intensity of the sample on the TiO2−PSi surface is almost 14 times than that on the thermally oxidized PSi surface in the same conditions. There is a low fluorescence background signal on the surfaces of both wafer samples. The result can be attributed to the following reasons: one is that the surface of TiO2−PSi is more stable than that of PSiO2;37 another is that the surface of TiO2−PSi has more active sites for DNA immobilization than that of PSiO2. The 14450


Research Article


which can be highly efficient for biomolecule immobilization;44 the surface of PSi is easy to chemically modify; PSi has a good compatibility with optics, microelectronics, and micro-electromechanical systems.18,37,45,46 TiO2−PSi has a more stable surface than PSiO2 and can further improve the signal/noise and detection sensitivity. Condition Optimization for Multiplex Mycotoxin Assay. The influence factors of fluorescence signals including the concentration of aptamer and antiaptamer, hybridization time, temperature, incubation time between mycotoxins, and hybridization duplex strands have been optimized. The results are shown in Figure S2. The optimal conditions are as follows: 15, 16, and 12 μmol/L concentrations of the aptamer for OTA, AFB1, and FB1, respectively; 75, 48, and 48 μmol/L concentrations of antiaptamer for OTA, AFB1, and FB1, respectively; hybridization time for 120 min in vitro, hybridization temperature of 25 °C; and incubation time for 120 min at room temperature. Calibration Curve for Multiplex Mycotoxin Assay. Under the optimal conditions, different concentrations of OTA, AFB1, and FB1 standard substrates were detected by the developed method. The relationship between fluorescence intensities and different concentrations of mycotoxins is shown in Figure 2. With the increase of the concentration of the three kinds of mycotoxins, the fluorescence intensities increase and reach to a plateau (Figure 2a−c). The increase of fluorescence intensities is in agreement with the principle of the designed method. The detection linear ranges are shown in Figure 2d−f. For OTA, AFB1, and FB1, the detection linear ranges vary from 0.1 to 10, 0.01 to 10, and 0.001 to 10 ng/mL, respectively. The limits of detection (LODs) are estimated to be 15.4, 1.48, and 0.21 pg/mL for OTA, AFB1, and FB1, respectively, according to the three times of signal/noise. The LODs are low than the previous reports on the surface of agarose-modified glass slides,11 diamino-poly(ethyleneglycol)-functionalized glass slides,4 96-well microtiter plate,47 and epoxy slides.42 The characteristic comparison of them for the multiplex mycotoxin detection is summarized in Table S1. The high sensitivity result can be attributed to the factors: (1) aptamer-based principle; (2) porous structure for probe immobilization; and (3) TiO2 nanolayer enhanced signal/noise. Specificity for Multiplex Mycotoxin Assay. The specificity for multiplex mycotoxin assay was evaluated among OTA, OTB, AFB1, and FB1. OTA, OTB, AFB1, and FB1 (100 μL, 1 ng/mL) were added dropwise on the samples which immobilized with the three kinds of the hybridized duplex strands of aptamers. The fluorescence intensities of the samples were obtained, and the result is shown in Figure 3. Among the multiplex mycotoxin samples, the fluorescence intensities of the samples can increase dramatically only when the mycotoxin molecules met their corresponding aptamers. The increased fluorescence intensities for positive samples are 5−12 times than those of negative samples. Between the structural analogue of OTA and OTB, the developed method can also recognize its target molecule. The results show that the developed method has a good specificity for OTA, AFB1, and FB1. The specificity mainly depends on the specificity of aptamers of mycotoxins. Evaluation in the Real Sample Detection. To evaluate the developed method for multiplex mycotoxin assay, 0.1, 1, and 10 ng/g multiplex mycotoxins were spiked in the wheat, corn, and rice samples and they have been detected with the new method. The recovery rates of the samples are shown in Figure 4a and Table S2. Among the recovery rates of samples,

Figure 4. Recovery rates of multiplex mycotoxins in the spiked wheat, corn, and rice samples at 0.1, 1, and 10 ng/g concentrations of mycotoxins (n = 3). (a) Recovery rates of the developed method and (b) recovery rates of the traditional ELISA.

aptamer probes. These hybridization duplex strands have been immobilized on the surfaces of TiO2−PSi through chemical bond linkage between GPTMS and amino groups of oligonucleotides. The hybridization duplex strands on the surface of TiO2−PSi show the fluorescence quenching because Cy3 at the 3′ end of aptamers and the quencher (BHQ2) at the 5′ end of their antiaptamers are very close. When OTA, AFB1, and FB1 appear on the surface of the wafer, the fluorescence signals are activated because the mycotoxins displace their antiaptamers and bind their aptamers. The different positions of aptamer probes will report which kind of mycotoxins and the fluorescence signal intensity will give the quantity of the different mycotoxins in the sample. For multiplex mycotoxin assay based on microarray methods, most of them have been established by the immunoassay principle on the 1D plane substrate.4,10,11,42,43 Generally, they require artificial antigens or mimotopes, antibodies, and secondary antibody labeled with dye. The preparation for these reagents is a complex process, especially for monoclonal antibodies for mycotoxins. In addition, the detection procedure is time-consuming and complicated. Aptamer techniques can overcome the disadvantages of immunoassay methods. Compared with the common microarrays on the 1D plane substrate, PSi surfaces show many advantages in the factors: they have large internal surface area (hundreds of m2/cm3) 14451



■

six of them are lower than 80%, one sample (0.1 ng/g corn) at 55.33%, and most of them are more than 80%. The recovery rates can be accepted for screening multiplex mycotoxins. We also detected the recovery rates of the same samples with the traditional ELISA method. They are shown in Figure 4b and Table S2. From Figure 4a, b and Table S2, the recovery rates for different cereal samples both the developed method and the traditional ELISA are mostly consistent. These results indicate that the developed method has a great potential in simultaneously screening the multiplex mycotoxins by the aptamer technique, although large applications in real samples still require to be further evaluated by the standard method (such as HPLC−MS/MS). Compared with the classic solid-phase immunomicroarrays, the new established method for multiplex mycotoxin screening is simple, sensitive, and costefficient.

CONCLUSIONS In this work, we designed a new aptamer microarray for multiplex mycotoxin screening on the TiO2−PSi surface. The TiO2 nanolayer on the PSi surface can enhance the fluorescence signal intensity and signal/noise. Three kinds of mycotoxins including OTA, AFB1, and FB1 have been used as a model for simultaneous screening of multiplex mycotoxins on the TiO2−PSi surface. The detection conditions have been optimized. The new developed method showed high sensitivity, wide detection linear ranges, and good recovery rates. The aptamer microarray on the stable TiO2−PSi surface can provide a simple, sensitive, and cost-efficient platform for simultaneous screening multiplex mycotoxins. The new method can be easily expanded to the other aptamer-based multiplex screening protocol. ASSOCIATED CONTENT

* Supporting Information S

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acsami.8b01431. Optical and structural characteristics of the TiO2−PSi surface; condition optimization for multiplex mycotoxin detection; specificity of multiplex assay for OTA, AFB1, and FB1; and images of fluorescence scanning for screening three kinds of mycotoxins (PDF)

■

REFERENCES

(1) Foubert, A.; Beloglazova, N. V.; Gordienko, A.; Tessier, M. D.; Drijvers, E.; Hens, Z.; De Saeger, S. Development of a Rainbow Lateral Flow Immunoassay for the Simultaneous Detection of Four Mycotoxins. J. Agric. Food Chem. 2017, 65, 7121−7130. (2) Beloglazova, N. V.; Graniczkowska, K.; Ediage, E. N.; Averkieva, O.; De Saeger, S. Sensitive Flow-through Immunoassay for Rapid Multiplex Determination of Cereal-borne Mycotoxins in Feed and Feed Ingredients. J. Agric. Food Chem. 2017, 65, 7131−7137. (3) Foubert, A.; Beloglazova, N. V.; De Saeger, S. Comparative Study of Colloidal Gold and Quantum Dots as Labels for Multiplex Screening Tests for Multi-mycotoxin Detection. Anal. Chim. Acta 2017, 955, 48−57. (4) Oswald, S.; Karsunke, X. Y. Z.; Dietrich, R.; Märtlbauer, E.; Niessner, R.; Knopp, D. Automated Regenerable Microarray-based Immunoassay for Rapid Parallel Quantification of Mycotoxins in Cereals. Anal. Bioanal. Chem. 2013, 405, 6405−6415. (5) Van Pamel, E.; Verbeken, A.; Vlaemynck, G.; De Boever, J.; Daeseleire, E. Ultrahigh-Performance Liquid Chromatographic-tandem Mass Spectrometric Multimycotoxin Method for Quantitating 26 Mycotoxins in Maize Silage. J. Agric. Food Chem. 2011, 59, 9747−9755. (6) Zhang, Z.; Hu, X.; Zhang, Q.; Li, P. Determination for Multiple Mycotoxins in Agricultural Products Using HPLC-MS/MS via a Multiple Antibody Immunoaffinity Column. J. Chromatogr. B 2016, 1021, 145−152. (7) Olsson, J.; Börjesson, T.; Lundstedt, T.; Schnürer, J. Detection and Quantification of Ochratoxin A and Deoxynivalenol in Barley Grains by GC-MS and Electronic Nose. Int. J. Food Microbiol. 2002, 72, 203−214. (8) Song, S.; Liu, N.; Zhao, Z.; Ediage, E. N.; Wu, S.; Sun, C.; De Saeger, S.; Wu, A. Multiplex Lateral Flow Immunoassay for Mycotoxin Determination. Anal. Chem. 2014, 86, 4995−5001. (9) Kong, D.; Liu, L.; Song, S.; Suryoprabowo, S.; Li, A.; Kuang, H.; Wang, L.; Xu, C. A Gold Nanoparticle-based Semi-quantitative and Quantitative Ultrasensitive Paper Sensor for the Detection of Twenty Mycotoxins. Nanoscale 2016, 8, 5245−5253. (10) Hu, W.; Li, X.; He, G.; Zhang, Z.; Zheng, X.; Li, P.; Li, C. M. Sensitive Competitive Immunoassay of Multiple Mycotoxins with Non-fouling Antigen Microarray. Biosens. Bioelectron. 2013, 50, 338− 344. (11) Wang, Y.; Liu, N.; Ning, B.; Liu, M.; Lv, Z.; Sun, Z.; Peng, Y.; Chen, C.; Li, J.; Gao, Z. Simultaneous and Rapid Detection of Six Different Mycotoxins Using an Immunochip. Biosens. Bioelectron. 2012, 34, 44−50. (12) Deng, G.; Xu, K.; Sun, Y.; Chen, Y.; Zheng, T.; Li, J. High Sensitive Immunoassay for Multiplex Mycotoxin Detection with Photonic Crystal Microsphere Suspension Array. Anal. Chem. 2013, 85, 2833−2840. (13) Wang, Y.; Ning, B.; Peng, Y.; Bai, J.; Liu, M.; Fan, X.; Sun, Z.; Lv, Z.; Zhou, C.; Gao, Z. Application of Suspension Array for Simultaneous Detection of Four Different Mycotoxins in Corn and Peanut. Biosens. Bioelectron. 2013, 41, 391−396. (14) Joshi, S.; Segarra-Fas, A.; Peters, J.; Zuilhof, H.; van Beek, T. A.; Nielen, M. W. F. Multiplex Surface Plasmon Resonance Biosensing and Its Transferability Towards Imaging Nanoplasmonics for Detection of Mycotoxins in Barley. Analyst 2016, 141, 1307−1318. (15) Joshi, S.; Annida, R. M.; Zuilhof, H.; van Beek, T. A.; Nielen, M. W. F. Analysis of Mycotoxins in Beer Using a Portable Nanostructured Imaging Surface Plasmon Resonance Biosensor. J. Agric. Food Chem. 2016, 64, 8263−8271. (16) Bonanno, L. M.; Kwong, T. C.; DeLouise, L. A. Label-Free Porous Silicon Immunosensor for Broad Detection of Opiates in a Blind Clinical Study and Results Comparison to Commercial Analytical Chemistry Techniques. Anal. Chem. 2010, 82, 9711−9718. (17) Bonanno, L. M.; DeLouise, L. A. Tunable Detection Sensitivity of Opiates in Urine via a Label-Free Porous Silicon Competitive Inhibition Immunosensor. Anal. Chem. 2010, 82, 714−722.

■

■

Research Article

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected], [email protected]. Phone: +86 25 83598286. Fax: +86 25 83598901. ORCID

Jianlin Li: 0000-0002-5267-3931 Author Contributions §

R.L., W.L., and T.C. contributed to this work equally and should be regarded as co-first authors. Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS The work was supported by National Natural Science Foundation of China no. 31471642. 14452


Research Article

ACS Applied Materials & Interfaces (18) Lin, V. S.-Y.; Motesharei, K.; Dancil, K.-P. S.; Sailor, M. J.; Ghadiri, M. R. A Porous Silicon-Based Optical Interferometric Biosensor. Science 1997, 278, 840−843. (19) Wang, J.; Lee, G. Y.; Kennard, R.; Barillaro, G.; Bisiewicz, R. H.; Lemus, N. A. C.; Cao, X. C.; Anglin, E. J.; Park, J. S.; Potocny, A.; Bernhard, D.; Li, J.; Sailor, M. J. Engineering the Properties of Polymer Photonic Crystals with Mesoporous Silicon Templates. Chem. Mater. 2017, 29, 1263−1272. (20) Krepker, M. A.; Segal, E. Dual-functionalized Porous Si/ hydrogel Hybrid for Label-free Biosensing of Organophosphorus Compounds. Anal. Chem. 2013, 85, 7353−7360. (21) Sohn, H.; Létant, S.; Sailor, M. J.; Trogler, W. C. Detection of Fluorophosphonate Chemical Warfare Agents by Catalytic Hydrolysis with a Porous Silicon Interferometer. J. Am. Chem. Soc. 2000, 122, 5399−5400. (22) Syshchyk, O.; Skryshevsky, V. A.; Soldatkin, O. O.; Soldatkin, A. P. Enzyme Biosensor Systems Based on Porous Silicon Photoluminescence for Detection of Glucose, Urea and Heavy Metals. Biosens. Bioelectron. 2015, 66, 89−94. (23) Gupta, B.; Mai, K.; Lowe, S. B.; Wakefield, D.; Di Girolamo, N.; Gaus, K.; Reece, P. J.; Gooding, J. J. Ultrasensitive and Specific Measurement of Protease Activity Using Functionalized Photonic Crystals. Anal. Chem. 2015, 87, 9946−9953. (24) Krismastuti, F. S. H.; Pace, S.; Voelcker, N. H. Porous Silicon Resonant Microcavity Biosensor for Matrix Metalloproteinase Detection. Adv. Funct. Mater. 2014, 24, 3639−3650. (25) Ouyang, H.; DeLouise, L. A.; Miller, B. L.; Fauchet, P. M. LabelFree Quantitative Detection of Protein Using Macroporous Silicon Photonic Bandgap Biosensors. Anal. Chem. 2007, 79, 1502−1506. (26) Schwartz, M. P.; Alvarez, S. D.; Sailor, M. J. Porous SiO2 Interferometric Biosensor for Quantitative Determination of Protein Interactions: Binding of Protein A to Immunoglobulins Derived from Different Species. Anal. Chem. 2007, 79, 327−334. (27) Orosco, M. M.; Pacholski, C.; Miskelly, G. M.; Sailor, M. J. Protein-Coated Porous-Silicon Photonic Crystals for Amplified Optical Detection of Protease Activity. Adv. Mater. 2006, 18, 1393− 1396. (28) Orosco, M. M.; Pacholski, C.; Sailor, M. J. Real-time Monitoring of Enzyme Activity in a Mesoporous Silicon Double Layer. Nat. Nanotechnol. 2009, 4, 255−258. (29) Zhang, H.; Jia, Z.; Lv, X.; Zhou, J.; Chen, L.; Liu, R.; Ma, J. Porous Silicon Optical Microcavity Biosensor on Silicon-on-insulator Wafer for Sensitive DNA Detection. Biosens. Bioelectron. 2013, 44, 89− 94. (30) Reta, N.; Michelmore, A.; Saint, C.; Prieto-Simón, B.; Voelcker, N. H. Porous Silicon Membrane-modified Electrodes for Label-free Voltammetric Detection of MS2 Bacteriophage. Biosens. Bioelectron. 2016, 80, 47−53. (31) Massad-Ivanir, N.; Mirsky, Y.; Nahor, A.; Edrei, E.; BonannoYoung, L. M.; Ben Dov, N.; Sa’ar, A.; Segal, E. Trap and Track: Designing Self-reporting Porous Si Photonic Crystals for Rapid Bacteria Detection. Analyst 2014, 139, 3885−3894. (32) Tenenbaum, E.; Segal, E. Optical Biosensors for Bacteria Detection by a Peptidomimetic Antimicrobial Compound. Analyst 2015, 140, 7726−7733. (33) Massad-Ivanir, N.; Shtenberg, G.; Raz, N.; Gazenbeek, C.; Budding, D.; Bos, M. P.; Segal, E. Porous Silicon-Based Biosensors: Towards Real-Time Optical Detection of Target Bacteria in the Food Industry. Sci. Rep. 2016, 6, 38099. (34) Massad-Ivanir, N.; Shtenberg, G.; Tzur, A.; Krepker, M. A.; Segal, E. Engineering Nanostructured Porous SiO2 Surfaces for Bacteria Detection via “Direct Cell Capture”. Anal. Chem. 2011, 83, 3282−3289. (35) Buriak, J. M. Organometallic Chemistry on Silicon and Germanium Surfaces. Chem. Rev. 2002, 102, 1271−1308. (36) Mun, K.-S.; Alvarez, S. D.; Choi, W.-Y.; Sailor, M. J. A Stable, Label-free Optical Interferometric Biosensor Based on TiO2 Nanotube Arrays. ACS Nano 2010, 4, 2070−2076.

(37) Li, J.; Sailor, M. J. Synthesis and Characterization of a Stable, Label-free Optical Biosensor from TiO2-coated Porous Silicon. Biosens. Bioelectron. 2014, 55, 372−378. (38) Tuerk, C.; Gold, L. Systematic Evolution of Ligands by Exponential Enrichment: RNA Ligands to Bacteriophage T4 DNA Polymerase. Science 1990, 249, 505−510. (39) Du, F.; Alam, M. N.; Pawliszyn, J. Aptamer-functionalized Solid Phase Microextraction−Liquid Chromatography/tandem Mass Spectrometry for Selective Enrichment and Determination of Thrombin. Anal. Chim. Acta 2014, 845, 45−52. (40) Bazin, I.; Tria, S. A.; Hayat, A.; Marty, J.-L. New Biorecognition Molecules in Biosensors for the Detection of Toxins. Biosens. Bioelectron. 2017, 87, 285−298. (41) Karunakaran, C.; Jayabharathi, J.; Jayamoorthy, K. Fluorescence Enhancing and Quenching of TiO2 by Benzimidazole. Sens. Actuators, B 2013, 188, 207−211. (42) Peltomaa, R.; Benito-Peña, E.; Barderas, R.; Sauer, U.; Andrade, M. G.; Moreno-Bondi, M. C. Microarray-Based Immunoassay with Synthetic Mimotopes for the Detection of Fumonisin B1. Anal. Chem. 2017, 89, 6216−6223. (43) Zhang, Z.; Li, P.; Hu, X.; Zhang, Q.; Ding, X.; Zhang, W. Microarray Technology for Major Chemical Contaminants Analysis in Food: Current Status and Prospects. Sensors 2012, 12, 9234−9252. (44) Ressine, A.; Ekström, S.; Marko-Varga, G.; Laurell, T. Macro-/ Nanoporous Silicon as a Support for High-Performance Protein Microarrays. Anal. Chem. 2003, 75, 6968−6974. (45) Wei, J.; Buriak, J. M.; Siuzdak, G. Desorption-ionization Mass Spectrometry on Porous Silicon. Nature 1999, 399, 243−246. (46) Chen, L.; Chen, Z.-T.; Wang, J.; Xiao, S.-J.; Lu, Z.-H.; Gu, Z.-Z.; Kang, L.; Chen, J.; Wu, P.-H.; Tang, Y.-C.; Liu, J.-N. Gel-pad Microarrays Templated by Patterned Porous Silicon for Dual-mode Detection of Proteins. Lab Chip 2009, 9, 756−760. (47) McNamee, S. E.; Bravin, F.; Rosar, G.; Elliott, C. T.; Campbell, K. Development of a Nanoarray Capable of the Rapid and Simultaneous Detection of Zearalenone, T2-toxin and Fumonisin. Talanta 2017, 164, 368−376.

14453


TiO2 Nanolayer-Enhanced Fluorescence for Simultaneous Multiplex

Recommend Documents