Surface-enhanced Raman Scattering Intensity Research Articles

An Easy and Low-cost Fabrication of AgNPs with High Performance in SERS

We study a cost effective and easy way to fabricate stable, uniform and large area surface-enhanced Raman scattering (SERS) substrates. The AgNPs with varying diameters have been fabricated through a thermally treating method on SiO2/Si substrate which present a high sensitivity, good uniformity and good stability. By using rhodamine 6G (R6G) molecule as analyte, the maximized detection limit is as low as 10−8 M. The deviation of SERS intensity by using proposed AgNPs SERS substrate is less than 15% which indicates its good uniformity. This work provides an efficiently way of fabricating industry SERS substrates which are good candidate in practical application in medicine, food safety and biotechnology.

Flexible PDMS-Based SERS Substrates Replicated from Beetle Wings for Water Pollutant Detection

The flexible surface-enhanced Raman scattering (SERS) sensor, which has the bionic 3D nanoarray structure of a beetle-wing substrate (BWS), was successfully prepared by replicated technology and thermal evaporation. The bionic structure was replicated with polydimethylsiloxane (PDMS) and then silver (Ag) nanoisland thin films were deposited by thermal evaporation. The deposition times and thicknesses (25-40 nm) of the Ag thin films were manipulated to find the optimal SERS detection capability. The Ag nanoisland arrays on the surface of the bionic replicated PDMS were observed by scanning electron microscope (SEM), X-ray diffraction (XRD), and contact angle, which can generate strong and reproducible three-dimensional hotspots (3D hotspots) to enhance Raman signals. The water pollutant, rhodamine 6G (R6G), was used as a model molecule for SERS detection. The results show that 35 nm Ag deposited on a PDMS-BWS SERS substrate displays the strongest SERS intensity, which is 10 times higher than that of the pristine BWS with 35 nm Ag coating, due to the excellent 3D bionic structure. Our results demonstrate that bionic 3D SERS sensors have the potential to be applied in wearable devices and sensors to detect biomolecules and environmental pollutants, such as industrial wastewater, in the future.

Evaluation of Surface-Enhanced Raman Scattering Substrate Consisting of Gold Nanoparticles Grown on Nanoarrays of Boehmite Fabricated using Magnetron Sputtering Process

A surface-enhanced Raman scattering (SERS) active structure allows the highly sensitive imaging of label-free molecular trace. A gold nanostructure with boehmite as a skeleton was fabricated by the inclined magnetron sputtering method. The characteristics of the prepared SERS imaging plate consisting of gold nanostructure on boehmite were evaluated as the follows. The distance dependence of the SERS intensity of 4,4′-bipyridine from the edge of the substrate indicated that the larger the SERS intensity becomes as the closer the distance approaches the substrate edged where the gold nanolayer was thicker. The trend of SERS dependence on distance was more pronounced at higher concentration of molecule and less pronounced at lower concentration. Using the SERS imaging plate will enable the further demonstration of ultrasenstive detection of chemical and biological molecules as environmental contaminants within a broad range of common fluidics for potential applications related to analytical chemistry and environmental monitoring.

In vivo surface-enhanced Raman scattering nanosensor for the real-time monitoring of multiple stress signalling molecules in plants.

When under stress, plants release molecules to activate their defense system. Detecting these stress-related molecules offers the possibility to address stress conditions and prevent the development of diseases. However, detecting endogenous signalling molecules in living plants remains challenging due to low concentrations of these analytes and interference with other compounds; additionally, many methods currently used are invasive and labour-intensive. Here we show a non-destructive surface-enhanced Raman scattering (SERS)-based nanoprobe for the real-time detection of multiple stress-related endogenous molecules in living plants. The nanoprobe, which is placed in the intercellular space, is optically active in the near-infrared region (785 nm) to avoid interferences from plant autofluorescence. It consists of a Si nanosphere surrounded by a corrugated Ag shell modified by a water-soluble cationic polymer poly(diallyldimethylammonium chloride), which can interact with multiple plant signalling molecules. We measure a SERS enhancement factor of 2.9 × 107 and a signal-to-noise ratio of up to 64 with an acquisition time of ~100 ms. To show quantitative multiplex detection, we adopted a binding model to interpret the SERS intensities of two different analytes bound to the SERS hot spot of the nanoprobe. Under either abiotic or biotic stress, our optical nanosensors can successfully monitor salicylic acid, extracellular adenosine triphosphate, cruciferous phytoalexin and glutathione in Nasturtium officinale, Triticum aestivum L. and Hordeum vulgare L.-all stress-related molecules indicating the possible onset of a plant disease. We believe that plasmonic nanosensor platforms can enable the early diagnosis of stress, contributing to a timely disease management of plants.

Exploring Intensity Distributions and Sampling in SERS-Based Immunoassays.

Surface-enhanced Raman scattering (SERS) is a sensitive, widely used spectroscopic technique. However, SERS is perceived as poorly reproducible and insufficiently robust for standard applications in analytical chemistry. Here, we demonstrated that reliable SERS immunoassay quantification at low concentrations (pM range) can be achieved by careful experimental design and appropriate data analysis statistics. A SERS-based immunoassay for IgG in human serum (3.1-50.0 ng mL-1 or 20.6-333 pM) was developed as a proof of concept. Calibration curves were created using the population median of the band area, centered at 592 cm-1, of a SERS reporter (Nile Blue A). Histograms of 7200 SERS spectra show lognormal distributions. SEM images of the sensor platform confirm a correlation between the number of SERS probes (ERLs) at the surface and the SERS intensity response. The IgG immunosensor reported here presented a limit of detection of 1.11 ng mL-1 or 7.39 pM and a limit of quantification of 9.04 ng mL-1 or 60.30 pM, within a 95% confidence level. The % error of the predicted versus the actual response of a quality control (QC) sample was 0.13%. The percent error of the QC sample decreases exponentially with the number of measurements. Randomly selected spatially separated measurements provided lower QC % error than a larger number of measurements that were closely spaced. We propose that it is necessary to describe the measured populations using an appropriate sample size for good statistics and consider the interrogation of sufficiently large and well-separated areas of the sensor surface to achieve a reliable sampling.

Three-Dimensional Surface-Enhanced Raman Scattering Platform with Hotspots Built by a Nano-mower for Rapid Detection of MRSA.

Methicillin-resistant Staphylococcus aureus (MRSA) has become one of the greatest threats to human health due to its strong drug resistance, wide distribution range, and high infection rate. Rapid identification of MRSA strains is very important for accurate diagnosis and early treatment of MRSA infections. Here, we introduced an Exo III-assisted nanomotor mower to build 3D hotspots for rapid detection of MRSA by surface-enhanced Raman scattering (SERS). As the bacteria bound to the aptamer, two trigger chains were released from the double-stranded structure, and the nano-mowers were activated by opening a hairpin probe on gold nanoparticles (AuNPs). With the continued cleavage of Exo III and cyclic release of the trigger chain, multiple hairpin DNAs on the AuNPs were cleaved to increase the motor power. The resulting nano-mower continued slicing protective DNA from larger AuNPs, exposing the AuNPs. Without the protection of DNA, Mg2+ in the buffer induced spontaneous aggregation of the AuNPs, and a large number of hotspots were formed for SERS measurements. Under optimal conditions, MRSA can be detected within 40 min, and the concentration of MRSA showed a good linear relationship with the SERS intensity at 1342 cm-1, with a limit of detection as low as 1 CFU/mL and a wide linear range (100 to 107 CFU/mL). This strategy creates a rapid bacterial detection method that performs well on actual samples utilizing portable Raman spectroscopy instruments, with potential applications in food detection, water detection, clinical treatment, and diagnosis.

Equilibria of semi-volatile isothiazolinones between air and glass surfaces measured by gas chromatography and Raman spectroscopy

Trace amounts of semi-volatile organic compounds (SVOCs) of the two isothiazolinones of 2-methylisothiazol-3(2H)-one (MIT) and 2-octyl-4-isothiazolin-3-one (OIT) were detected both in the air and on glass surfaces. Equilibria of SVOCs between air and glass were examined by solid phase microextraction-gas chromatography/mass spectrometry (SPME-GC/MS). Surface to air distribution ratios of Ksa for MIT and OIT were determined to be 5.10 m and 281.74 m, respectively, suggesting more abundant MIT in the gas phase by a factor of ∼55. In addition, a facile method of silver nanocube (AgNC)-assisted surface-enhanced Raman scattering (SERS) has been developed for the rapid and sensitive detection of MIT and OIT on glass surfaces. According to MIT and OIT concentration-correlated SERS intensities of Raman peaks at ∼1585 cm−1 and ∼1125 cm−1, respectively. Their calibration curves have been obtained in the concentration ranges between 10−3 to 10−10 M and 10−3 to 10−11 M with their linearity of 0.9986 and 0.9989 for MIT and OIT, respectively. The limits of detection (LODs) of the two isothiazolinones were estimated at 10−10 M, and 10−11 M for MIT and OIT, respectively. Our results indicate that AgNC-assisted SERS spectra are a rapid and high-ultrasensitive method for the quantification of MIT and OIT in practical applications. The development of analytical methods and determination of the Ksa value obtained in this study can be applied to the prediction of the exposure to MIT and OIT from various chemical products and dynamic behaviors to assess human health risks in indoor environments.

Surface-enhanced Raman scattering integrated with microfluidic device fabricated using atomic force microscopy tip-based nanomachining approach

Nanostructure-based surface-enhanced Raman scattering (SERS) substrates have drawn increasing interest because of their wide variety of applications. In particular, SERS integrated with microfluidic devices have shown merit in detecting liquid solvents. In this study, a SERS–microfluidic device is prepared using the atomic force microscopy (AFM) tip-based nanoscratching technique. The influence of the normal load on the period and amplitude of the machined nanogroove are investigated. Nanodot arrays are also fabricated using a twice-scratching strategy. The effects of the feed value and scratching angle on the morphologies of the nanodot arrays are studied, and the Raman spectra of rhodamine 6G (R6G) are detected based on the fabricated nanostructures. The influences of the Au film thickness and period of the nanostructure on the SERS intensity are studied and agree well with the simulated results obtained using the COMSOL software. Furthermore, the Raman spectra of R6G obtained by the SERS substrate and SERS–microfluidic device are compared. The Raman spectra of a mixture of R6G and malachite green (MG) are also measured using the SERS-microfluidic device. In principle, the method reported here could be implemented to prepare SERS microfluidic devices used in biological or chemical molecular detection.

Metal–Organic-Frameworks-Isolated Au Nanobipyramids as Synergetic Surface-Enhanced-Raman-Scattering Substrates

Recently, mushrooming efforts in surface-enhanced Raman scattering (SERS) have been devoted to applying semiconductor-like metal–organic frameworks (MOFs) as a charge-transfer center rather than only a porous filter or stabilizing layer in a metal@MOF core–shell substrate. However, the influence of an enhanced electric field on the charge-transfer process of MOFs has not been quantitatively explored, leading to an elusive understanding of the synergetic effect of metal@MOF core–shell substrates. Here we reveal a synergetic effect through SERS measurements of gold nanobipyramid (Au NBP) @zeolitic-imidazolate-framework (ZIF) core–shell nanostructures with varied thickness and composition of the shell. The synergetic effect was confirmed by the stronger enhancement factors of some NBP@ZIFs than that of pure NBP-785 with methyl orange (MO) and rhodamine 6G as the probe. Moreover, a reorientation phenomenon of MO discovered in the ZIF shell probably also accounted for the higher intensity, given that the probe orientation could impact the SERS intensity. Besides elucidating the charge transfer and synergy effect of the metal@MOF core–shell SERS substrates, this work could also provide new ideas to enrich the family of the shell-isolated nanoparticle-enhanced Raman spectroscopy substrates by employing porous materials as the shell.

Combining thin-film microextraction and surface enhanced Raman spectroscopy to sensitively detect thiram based on 3D silver nanonetworks

By coupling thin-film microextraction (TFME) with surface enhanced Raman scattering (SERS), a facile method was developed for the determination of thiram in the complex matrix (orange juice or grape peel). The substrate of TFME was made by self-assembling silver sol on the silicon wafer to form a three-dimensional (3D) silver nanonetwork structure, without adding any template, which was used for TFME and SERS detection, respectively. The substrate exhibits high reproducibility with a relative standard deviation of about 7.32 % in spot and spot SERS intensity. The SERS signal intensity at a shift of 1384 cm−1 and the thiram concentration showed good linearity in the range of 0.01–5 µg/L and the linear correlation coefficient was 0.9912. The detection limit for thiram was found to be 0.01 µg/L. The TFME-SERS method was applied for the determination of thiram in fruit juice and the results were obtained very well. Therefore, this method is expected to play a role in the detection of trace pollutants.

TiO2 Thickness-dependent charge transfer effect in p-aminothiophenol molecules chemisorbed on TiO2/Ni substrates

Semiconductors have been modulated in thickness to optimize their surface-enhanced Raman scattering (SERS) activity in noble metal/semiconductor SERS substrates. However, the charge transfer (CT) resonance mechanism caused by the change of the semiconductor thickness has not been fully clarified yet, due to the influence of the strong surface plasmon resonance (SPR) effect from the noble metals. Here, systems of p-aminothiophenol (PATP) molecules chemisorbed on TiO2/Ni nanopillar array films with precisely controlled TiO2 thicknesses (PATP/TiO2/Ni) were developed to systematically evaluate the TiO2 thickness-dependent CT mechanism on the premise of minimizing the SPR influence. Ultraviolet–visible, photoluminescence and X-ray photoelectron spectroscopy results demonstrated that four parts that ascribed to the SERS enhancement, photo-induced CT from Ni to TiO2, resonance excitation of TiO2, CT from TiO2 surface states to PATP molecules, and the molecular resonance of PATP molecules, are highly TiO2-thickness dependent. Hence the whole system exhibits a strong TiO2-thickness-dependent CT effect (at the two interfaces of Ni-TiO2 and TiO2-PATP) and SERS activity with a maximum SERS intensity at a TiO2 thickness of 40 nm. This work shall be valuable for future developing an optimal metal/semiconductor SERS substrates and obtaining an in-depth understanding of the semiconductor-thickness-dependent charge transfer mechanism for SERS applications.

Uniform and Controllable Preparation of Ag–Au Composite Cascade Hollow Nanoarrays and Applications in SERS Trace Molecules Detection

In recent years, surface-enhanced Raman scattering (SERS) technique based on localized electromagnetic field enhancement on noble metal surfaces has received extensive attention in the field of trace molecule sensing and detection. However, in the process of practical application, the current SERS detection performance is still unable to achieve high detection sensitivity and high repeatability at the same time. In this paper, an efficient and controllable preparation method of Ag–Au composite cascade hollow nanoarray SERS substrates were provided based on nanoimprinting, conformal transfer and electrodeposition techniques. Crystal Violet (CV) was used as the probe molecule, and a low relative standard deviation of 6.65% of SERS intensity was obtained, and the detection concentration could be as low as 10[Formula: see text][Formula: see text]M, which can meet the needs of practical applications. The structure has multi-scale cascade characteristics, and significantly broadens the electromagnetic field enhancement characteristics of traditional single-scale configuration nanostructures on the premise of ensuring the uniformity of SERS detection. Such substrates can provide more abundant molecular adsorption sites, which is conducive to improving SERS detection sensitivity and stability. This method is universal, simple and with controllable and repeatable preparation process, which has good application potential in the construction of large-area uniform cascaded nanoarray structure SERS substrates.

Crystal-amorphous Ni(OH)2 nanocages as SERS substrate with conspicuous defects-induced charge-transfer resonance for ultrasensitive detection of MicroRNA 155

Herein, an innovative Ni(OH)2 nanocages (Ni(OH)2 NCs) with crystal-amorphous structure were fabricated as surface-enhanced Raman scattering (SERS) substrate, which realized excellent SERS enhancement by the significant defects-induced charge transfer resonance and was applied to the construction of SERS biosensor for ultrasensitive microRNA 155 (miRNA 155) detection. The surface oxygen vacancy (Ovs) and defective phases endowed Ni(OH)2 NCs the increased charge carrier density and preponderant energy-level matching with signal molecules methylene blue (MB), thereby inducing the remarkable charge transfer resonance via the augment of electron transition probability for improving the SERS effect of Ni(OH)2 NCs. Impressively, the SERS performance of Ni(OH)2 NCs was stronger than that of amorphous Ni(OH)2 nanocages (a-Ni(OH)2 NCs), ascribing to the abundant Ovs and high degree of charge transfer (ρCT) in Ni(OH)2 NCs. Furthermore, the limited target miRNA 155 was transformed into the plentiful MB molecules by employing the target-related cleavage amplification reaction and hybridization chain reaction (HCR), thus achieving an enhanced SERS intensity for detecting target miRNA 155 based on Ni(OH)2 NCs substrate and obtaining a low detection limit of 30 aM. This strategy developed candidate materials for the practical applications of SERS technology and provided a promising method to disease diagnosis.

Controllable hot electron transfer in the Ag/MoO3 layer by layer system: Thickness-dependent MoO3 layer

The Ag and MoO3 layer-by-layer sputtering method was employed to fabricate Ag/MoO3 coated on a polystyrene (PS) array (Ag/MoO3@PS), which exhibited excellent surface-enhanced Raman scattering (SERS) activity. The thickness of the MoO3 layer was controlled by changing the sputtering power. The SERS intensity of 4-aminothiophenol (PATP) on Ag/MoO3@PS with a 2 nm thickness of the MoO3 layer was comparable to that on pure Ag coated on the PS array (Ag@PS). This is possible because hot electrons were injected from Ag into the MoO3 layer to enhance the photocatalyst reaction; thus, the SERS spectra of coupled PATP were obtained. The transport of hot electrons rapidly decayed and was blocked with increasing thickness of the MoO3 layer from 2 nm to 9 nm. Thus, the SERS intensity decreased, and interestingly, the b2 mode of PATP decreased and nearly disappeared. This study provides new insight into the control of hot electron reduction for catalytic reduction process monitoring.

Rapid Detection of Clenbuterol Residues in Pork Using Enhanced Raman Spectroscopy.

Clenbuterol (CB) is a synthetic β-receptor agonist which can be used to improve carcass leanness in swine, but its residues in pork also pose health risks. In this report, surface-enhanced Raman scattering (SERS) technology was used to achieve rapid detection and identification of clenbuterol hydrochloride (CB) residues. First, the effects of several different organic solvents on the extraction efficiency were compared, and it was found that clenbuterol in pork had a better enhancement effect using ethyl acetate as an extraction agent. Then, SERS signals of clenbuterol in different solvents were compared, and it was found that clenbuterol had a better enhancement effect in an aqueous solution. Therefore, water was chosen as the solvent for clenbuterol detection. Next, enhancement effect was compared using different concentration of sodium chloride solution as the aggregating compound. Finally, pork samples with different clenbuterol content (1, 3, 5, 7, 9, and 10 µg/g) were prepared for quantitative analysis. The SERS spectra of samples were collected with 0.5 mol/L of NaCl solution as aggregating compound and gold colloid as an enhanced substrate. Multiple scattering correction (MSC) and automatic Whittaker filter (AWF) were used for preprocessing, and the fluorescence background contained in the original Raman spectra was removed. A unary linear regression model was established between SERS intensity at 1472 cm-1 and clenbuterol content in pork samples. The model had a better linear relationship with a correlation coefficient R2 of 0.99 and a root mean square error of 0.263 µg/g. This method can be used for rapid screening of pork containing clenbuterol in the market.

Electrochemically assisted wide area Raman with standard curved surface quantification method

Reproducibility is still a great challenge for surface-enhanced Raman scattering (SERS), because the uncontrollable fabrication of SERS substrates or the uneven distribution of samples on the substrate result in the signal fluctuation with or between the substrates. Herein, a novel SERS quantitative method with good reproducibility was proposed. It is based on the basic principle that the SERS signal intensity is not only related to electromagnetic enhancement and the concentration of sample, but also related to the specific surface area of the substrate. The surface area information of the substrate is obtained through electrochemical technology, and then introduced into the standard curve with the linear relationship of concentration of sample and SERS intensity as a new variable to obtain a 3D standard curved surface, which effectively corrects the signal difference between the substrates, and combines the wide area Raman method to reduce the difference within the substrate, thereby improving the reproducibility of SERS quantitative detection. Using malachite green (MG) as the probe molecule and using cyclic voltammetry to calculate the substrate area fitted plane model (CV-standard curved surface), the root mean square error (RMSE) of the predicted result is 0.26 and the relative error (RE) is 0.25. It shows that the detection error significantly reduces comparing with the traditional standard curve method. Also, the proposed method can be used in other SERS quantitative detection and has potential application prospects.

Novel mesoporous silica surface loaded gold nanocomposites SERS aptasensor for sensitive detection of zearalenone

Mycotoxin contamination is a severe threat to global food security, thus fast and effective detection of mycotoxins is of great significance. Herein, mesoporous silica surface loaded gold nanocomposites (MSN-Rh6G-AuNPs) were prepared as surface-enhanced Raman scattering (SERS) substrate, and the SERS aptasensor (MSN-Rh6G-AuNPs@apt) was further obtained by aptamer functionalization which can realize the quantitative and sensitive detection of zearalenone (ZEN). The small nanogaps between AuNPs made MSN-Rh6G-AuNPs present strong SERS performance under excitation light irradiation, while the aptamer performed the functions of ZEN recognition and Raman signal masking. The acquired results revealed that the SERS intensity at 1508 cm−1 had a good linear relationship with ZEN concentration of 3–200 ng/mL and the limit of detection (LOD) was calculated to be 0.0064 ng/mL. In addition, the designed SERS aptasensor was successfully applied to the detection of ZEN in corn, indicating great potential in practical implications.

Controllable fabrication of silver-deposited polyurethane acrylate nanopillar array film as a flexible surface-enhanced Raman scattering (SERS) substrate with high sensitivity and reproducibility.

Acontrollable method for fabricating flexible surface-enhanced Raman scattering (SERS) substrates is demonstratedby depositing silver onto a flexible nanopillar array film. The flexible nanopillar array film was cost-effectively prepared by replicating an anodic aluminum oxide (AAO) template with UV-curable polyurethane acrylate (PUA) over a large area. Then, the deposition of silver was done by an Ar-assisted thermal evaporation. In the deposition process, the partial pressure of Ar was optimized because it has a significant influence on the SERS intensity through the microstructural changes of silver deposited on PUA nanopillars. In addition, the increase in the nanopillar diameter and height enhanced the SERS intensity obtained at 785-nm excitation because of the increased number of hot spots. However, the agglomeration of Ag-deposited nanopillars, which is caused by high aspect ratios, negatively affected the SERS performance in terms of intensity and standard deviation. The optimized Ag-deposited nanopillar array film with nanopillar diameters and heights of 80nm and 200nm exhibited excellent SERS sensitivity and signal reproducibility with stable mechanical flexibility. For application in food and biomedical analysis, it was used for detecting saccharin and peptide and showed a good linear relationship between the SERS intensity and concentration. These findings demonstrate the suitability of our method for the controllable fabrication and optimization of flexible SERS substrates with high sensitivity and reproducibility.

SERS detection of anthraquinone dyes: Using solvothermal silver colloid as the substrate

Anthraquinone dyes have been widely used to color textile fibers since antiquity. Identification of the dyes can help us understand the dyeing processes and when and where the textiles were produced. Herein, we present a strategy based on surface-enhanced Raman scattering (SERS) with a novel silver colloid substrate for the detection of anthraquinone dyes. Quasi-spherical silver particles with different sizes were prepared by the solvothermal method and then characterized by transmission electron microscopy (TEM). The silver colloid substrates exhibited high-density hot spots with good reproducibility (RSDs of 3 ∼ 16 %) and high sensitivity. Among them, Ag-C2 (the molar ratio of AgNO3 to PVP is 0.367, reacted for 2 h) was used to detect anthraquinone dyes in reference silk fibers as well as ancient textile samples due to the highest sensitivity and the low RSD (5.37 %) in this study. More importantly, Ag-C2 can be utilized to distinguish three madder species (Rubia tinctorum, Rubia cordifolia, and Rubia argyi) depending on the SERS intensity of alizarin and purpurin.

High-efficiency enzyme-free catalyzed hairpin assembly-mediated homogeneous SERS and naked-eyes dual-mode assay for ultrasensitive and portable detection of mycotoxin

We developed an aptamer recognition-trigged enzyme-free catalyzed hairpin assembly (CHA) assisted signal amplification homogeneous naked-eyes and surface-enhanced Raman scattering (SERS) dual-mode sensor for highly sensitive and portable detection of Aflatoxin B1 (AFB1) in food samples. The recognition of AFB1 by aptamer induced the generation of HP1-AFB1 complexes, which hybridized with Ag+-labeled hairpin DNA (HP2) and released Ag+, subsequently initiating the enzyme-free CHA reaction by a designed helper DNA (HP3) to form double-stranded DNA (HP2-HP3) and accompanied by the release of HP1-AFB1 complexes. The released HP1-AFB1 complexes were recognized by HP2 and HP3 again to trigger cascade recycling amplification and resulted in the generation of a larger number of free Ag+ and dsDNA. Then, methylene blue as Raman tag to intercalate into dsDNA and generating strong SERS signal with the assistance of Fe3O4@Au. Meanwhile, the free Ag+ induced the AuNPs aggregation and resulted in naked-eye distinguishable color transitions from red to black blue. Benefitting from the efficiently enzyme-free CHA assisted signal amplification and portably dual-mode detection system, this work successfully proposed a novel homogeneous biosensing strategy for highly sensitive and portable detection of AFB1. The SERS intensity and visualization signals were linearly correlated with the concentration of AFB1 ranging from 0.0156 to 31.2 ng mL−1 and 0.61–39 ng mL−1, and the limit of detections were 1.6 pg mL−1 and 152 pg mL−1, respectively. This strategy was successfully applied to real samples and provided an alternative approach for the highly sensitive detection of mycotoxins.