Aggregation Of AuNPs Research Articles

Enzymatic reaction modulated gold nanoparticle aggregation-induced photothermal and smartphone readable colorimetry dual-mode biosensing platform for trypsin detection in clinical samples

There is an urgent demand to develop a portable and user-friendly biosensing platform for accurately and rapidly detecting biomarkers in clinical diagnosis. In this work, a photothermal and smartphone-based colorimetric dual-mode biosensing platform was proposed for trypsin assay based on the localized surface plasmon resonance (LSPR) effect of gold nanoparticles (Au NPs). Two competing processes were presented between the protection and the destabilization of dispersed Au NPs, respectively. Bovine serum albumin (BSA) can restrain the Au NPs aggregation due to the surface protection of Au NPs in the salt solution. In the presence of trypsin, the Au NPs are aggregated due to the enzymatic digestion of surface BSA ligand and electrostatic interaction, resulting strong photothermal effect and obvious RGB (Red/Green/Blue) value change (color from red to blue). The whole process can be performed within 1 h and the point-of-care testing (POCT) was realized by using a thermometer and smartphone as signal recorders. The limits of detection (LODs) were calculated to be 6 µg mL−1 by photothermal sensing and 1.2 µg mL−1 by RGB recognition. This biosensing platform was successfully used for trypsin assay in clinical acute pancreatitis samples and showed great consistency with clinical diagnostic results, validating the potential POCT application.

Target-induced gold nanoparticles colorimetric sensing coupled with aptamer for rapid and high-sensitivity detecting kanamycin

Herein we report a novel colorimetric sensing strategy for the detection of kanamycin (kana) based on target-induced gold nanoparticles (AuNPs) coupled with aptamers. Aptamer-functionalized AuNPs, as the colorimetric probe, showed a distinct red shift with addition of kana, which avoiding the tedious and unnecessary additive-induced process. To study the interaction between kana and AuNPs and the effects of the specific aptamer adsorption, a series of experiments including UV–vis absorbance and surface enhanced Raman spectroscopy (SERS) were performed. Based on the results, a new alternative view is proposed that kana can directly induce the aggregation of aptamer-wrapped AuNPs, attributed to the co-adsorption of kana and aptamer on the surface of AuNPs. The proposed colorimetric sensing exhibited high selectivity and sensitivity for kanamycin assay with a wide linear range from 10.0 nM to 4.0 μM, and the limit of detection (LOD) reached 4.0 nM. Moreover, the whole detection process could be completed within 5 min, and it also achieved excellent performance in real samples detection with recoveries in the range of 86.22–109.89%. The results indicate that target-induced AuNPs colorimetric sensing coupled with aptamers for the direct detection of kana is simple, rapid and high-sensitivity, has the promising potential applications in the fields of food safety and environmental monitoring.

Two-step aggregation of gold nanoparticles based on charge neutralization for detection of melamine by colorimetric and surface-enhanced Raman spectroscopy platform.

A colorimetric and surface-enhanced Raman scattering (SERS) signal amplification platform based on 2-step aggregation of gold nanoparticles (AuNP) was constructed for the sensitive detection of melamine. In this study, the positively charged SYBR Green I was used for the first step of aggregation of AuNP, via charge neutralization, to obtain small-sized AuNP aggregates. The positively charged SYBR Green I decreased the negative charges of the surface of AuNP, which was beneficial to the aggregation of AuNP. In addition, the melamine could aggregate AuNP by decreasing the negative charges of the surface of AuNP and self-assemble with each other on the surface of AuNP by hydrogen bonds. Therefore, the second efficient aggregation of small-sized AuNP aggregates could be achieved with melamine at low concentration, resulting in significant signal changes of color and SERS. The sensitivity of a colorimetric (0.60 mg/L) and SERS (0.089 mg/L) platform, based on 2-step aggregation of AuNP, was 15 and 2.2 times higher than that based on 1-step aggregation of AuNP for detecting melamine.

Understanding the Excitation Wavelength Dependence and Thermal Stability of the SARS-CoV-2 Receptor-Binding Domain Using Surface-Enhanced Raman Scattering and Machine Learning.

COVID-19 has cost millions of lives worldwide. The constant mutation of SARS-CoV-2 calls for thorough research to facilitate the development of variant surveillance. In this work, we studied the fundamental properties related to the optical identification of the receptor-binding domain (RBD) of SARS-CoV-2 spike protein, a key component of viral infection. The Raman modes of the SARS-CoV-2 RBD were captured by surface-enhanced Raman spectroscopy (SERS) using gold nanoparticles (AuNPs). The observed Raman enhancement strongly depends on the excitation wavelength as a result of the aggregation of AuNPs. The characteristic Raman spectra of RBDs from SARS-CoV-2 and MERS-CoV were analyzed by principal component analysis that reveals the role of secondary structures in the SERS process, which is corroborated with the thermal stability under laser heating. We can easily distinguish the Raman spectra of two RBDs using machine learning algorithms with accuracy, precision, recall, and F1 scores all over 95%. Our work provides an in-depth understanding of the SARS-CoV-2 RBD and paves the way toward rapid analysis and discrimination of complex proteins of infectious viruses and other biomolecules.

Reversible and Irreversible HAuCl4 Binding to DNA for Seeded Gold Nanoparticle Growth and Opposite DNA and Aptamers Colorimetric Sensing Outcomes

AbstractDNA‐directed seeded growth of gold nanoparticles has been used for the development of aptamer‐based biosensors with the assumption that target analytes can modulate the adsorption of aptamers to the gold seeds and thus affect the growth reaction. To understand the reaction, the effect of single‐ and double‐stranded DNA is first examined, and it is found that they have a similar promotion effect of anisotropic growth, suggesting that DNA cannot be detected using this method. By studying the interaction between HAuCl4 and DNA, both weak reversible binding and strong irreversible binding are identified, with the latter becoming dominating with a longer incubation time. Single‐ and double‐stranded DNA have similar weak binding to HAuCl4, and this weak binding is more important for the growth reaction. Then three aptamers are tested, where only cortisol appeared to modulate its aptamer adsorption and the growth reaction reflected aptamer binding. Hg2+ shows no advantage for its aptamer, and quinine induced aggregation of AuNPs cannot be detected by this reaction either. Therefore, each aptamer target needs to be individually studied to test if this method is applicable. It is also noted that DNA and aptamers have opposite outcomes for the target‐dependent growth reactions.

A colorimetric detection of polystyrene nanoplastics with gold nanoparticles in the aqueous phase

Nanoplastics has become a growing environmental concern because these tiny particles can easily penetrate biological tissues and have possible toxic effects. FT-IR and Raman spectroscopy methods are currently used to analyze microplastics (5 mm or less), but they encounter difficulty when the particles are below 1 μm. On the other hand, thermoanalysis of nanoplastics does not provide the size information. Therefore, herein, we proposed the colorimetric detection method with gold nanoparticles (AuNPs) to measure the concentration of polystyrene nanoplastics (PSNPs, size = 350 and 880 nm) through a color change that is obvious to the naked eye. A mixed dispersion of PSNPs and AuNPs was added with acetone, a good solvent for polystyrene. In this colorimetric detection, acetone acted as a key component to enhance or hinder the aggregation of AuNPs around PSNPs. Namely, acetone itself promoted AuNPs aggregation, but it was dissolved partially PS chains from PSNSs to act as inhibitor of aggregation of AuNPs. These two contradictory feature of acetone to AuNPs and PSNPs affect the aggregation and color of AuNPs (dispersed = red, aggregated = blue). Finally, the heat-map between PSNSs and acetone was prepared to use for estimation of concentration of PSNPs in the aqueous solution with naked eye. To the best of our knowledge, this is the first attempt to measure nanoplastics by colorimetry.

Self-Assembled Au Nanoparticle Monolayers on Silicon in Two- and Three-Dimensions for Surface-Enhanced Raman Scattering Sensing.

Gold nanoparticle/silicon composites are canonical substrates for sensing applications because of their geometry-dependent physicochemical properties and high sensing activity via surface-enhanced Raman spectroscopy (SERS). The self-assembly of gold nanoparticles (AuNPs) synthesized via wet-chemistry on functionalized flat silicon (Si) and vertically aligned Si nanowire (VA-SiNW) arrays is a simple and cost-effective approach to prepare such substrates. Herein, we report on the critical parameters that influence nanoparticle coverage, aggregation, and assembly sites in two- and three-dimensions to prepare substrates with homogeneous optical properties and SERS activity. We show that the degree of AuNP aggregation on flat Si depends on the silane used for the Si functionalization, while the AuNP coverage can be adjusted by the incubation time in the AuNP solution, both of which directly affect the substrate properties. In particular, we report the reproducible synthesis of nearly touching AuNP chain monolayers where the AuNPs are separated by nanoscale gaps, likely to be formed due to the capillary forces generated during the drying process. Such substrates, when used for SERS sensing, produce a uniform and large enhancement of the Raman signal due to the high density of hot spots that they provide. We also report the controlled self-assembly of AuNPs on VA-SiNW arrays, which can provide even higher Raman signal enhancement. The directed assembly of the AuNPs in specific regions of the SiNWs with a control over NP density and monolayer morphology (i.e., isolated vs nearly touching NPs) is demonstrated, together with its influence on the resulting SERS activity.

Plasmonic sensing of alkaline phosphatase and its inhibitors through Ag(I)-mediated assembly of gold nanoparticles

Alkaline phosphatase (ALP) is of extraordinary importance in living organisms and widely serves as a labeling enzyme in biochemical assays. Conventional methods based on the colorimetric readout of chemicals have issues in the photosensitivity and the difficulty in visibly distinguishing the color intensity. Herein, we developed a plasmonic assay for detecting ALP activity and its inhibitors based on gold nanoparticles (AuNPs) with good stability and naked-eye readout. Ag(I) specifically oxidizes TMB to produce positively charged oxTMB, which electrostatically aggregates negatively charged AuNPs. ALP as an enzyme specifically hydrolyzes a substrate to generate ascorbic acid, which reduces Ag(I) and modulates the aggregation of AuNPs. This plasmonic ALP assay has a linear detection range of 5–50 mU/mL with a limit of detection of 0.39 mU/mL. In combination with a smartphone, it enables monitoring ALP inhibitors including dimethoate and arsenic that are environmental contaminants. This plasmonic sensing strategy with good stability, visible readout, high specificity, low cost, and ease of operation provides a promising platform for enzyme detection and environmental monitoring.

A new colorimetric method for determination of formaldehyde in sea food based on anti-aggregation of gold nanoparticles

A new colorimetric method based on anti-aggregation of gold nanoparticles (AuNPs) in the presence of melamine for sensitive and selective determination of formaldehyde was developed. The citrate capped AuNPs was synthesized by Turkevich method. A certain concentration of melamine is responsible for color change of AuNPs from red to purple. The surface plasmon resonance peak was shifted from 520 to 640 nm. In the presence of formaldehyde, the reaction between melamine and formaldehyde to form methylol melamine was occurred, which resulted in the decreasing of aggregation of AuNPs. Based on the anti-aggregation mechanism, formaldehyde can be detected by observing the color change of AuNPs solution containing melamine, which was monitored by UV–visible spectrophotometer. Calibration curve plotted between absorbance ratio (A640/A520) and formaldehyde concentration was made with linearity of 0 – 2000 µg L−1. The limit of detection and the limit of quantitation were found at 26.0 µg L−1 and 88.0 µg L−1, respectively. The method also provided high accuracy (%recovery in range 97.3 – 104%) and high precision (%RSD < 5.6).

Self-assembly of gold nanoparticles by chitosan for improved epinephrine detection using a portable surface enhanced Raman scattering device

Surface enhanced Raman scattering (SERS) has become widely used for identification, quantification and providing structural information about molecular structure in low concentrations as it allows signal Raman enhancement using metallic nanoparticles (NPs). Controlling interaction between analyte and NPs is a major point for the optimization of signal exaltation in SERS analysis. The objective of this study is the improvement and the control of SERS analysis by aggregation/self-assembly optimization of AuNPs using quaternized chitosan. The interest of this approach is to allow stable and reliable measurements with a simple and low cost approach compatible with a massive use in the field. In this work, we used design of experiments by Box-Behnken design to fix optimized conditions to increase signal sensibility of epinephrine water solutions. We also tested SERS signal stability in isotonic sodium chloride 0.9% and glucose 5% matrices.Our results demonstrate that globally neutral AuNPs aggregates were stabilized at a nanometric size by the subsequent addition of polyelectrolyte chains and allows for significant Raman signal enhancement of epinephrine. We succeed to prepare the SERS active material and measure a stable signal of epinephrine at a concentration as down as 0.1 μg mL−1 in less than 5 min. The signal remained stable and exploitable for at least 2 h. Our results reveal a strong correlation between intensity and logarithm of the concentration (concentration before dilution from 0.1 to 10 μg mL−1) suggesting a possible quantification. Furthermore, the signal of epinephrine at 10 μg mL−1 were also exploitable and stable in complex media as isotonic sodium chloride 0.9% and glucose 5%. This represents a particularly interesting application that would allow direct analysis of drugs complex media and open the way to analysis in biological samples.

NanoSuit-Assisted Liquid-Cell Scanning Electron Microscopy Enables Dynamic Gold Nanoparticle Monitoring for the Aggregation and Transmembrane Processes in Living Cells.

Dynamic observation of the behaviors of nanomaterials in the cellular environment is of great significance in mechanistic investigations on nanomaterial-based diagnostics and therapeutics. Realizing label-free observations with nanometer resolution is necessary but still has major challenges. Herein, we propose a NanoSuit-assisted liquid-cell scanning electron microscopy (NanoSuit-LCSEM) method that enables imaging of the behaviors of nanoparticles in living cells. Taking A549 cells and gold nanoparticles (AuNPs) as a cell-nanoparticle interaction model, the NanoSuit-LCSEM method showed a significantly improved resolution to 10 nm, which is high enough to distinguish single and two adjacent 30 nm AuNPs in cells. The continuous observation time for living cells is extended to 30 min, and the trajectories and velocities for the transmembrane movement of AuNP aggregates are obtained. This study provides a new approach for dynamic observation of nanomaterials in intact living cells and will greatly benefit the interdisciplinary research of nanomaterials, nanomedicine, and nanotechnology.

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.

Dual-mode colorimetric determination of As(III) based on negatively-charged aptamer-mediated aggregation of positively-charged AuNPs

The aggregation and redispersion of positively-charged AuNPs ((+)AuNPs) modified with cysteamine (CS) could be regulated by the negatively charged As(III)-specific aptamer (As(III)-apt). In general, (+)AuNPs aggregated with increasing inducer concentration. However, in the present study, it was found that (+)AuNPs re-dispersed after a certain high concentration of As(III)-apt was reached. By optimizing the concentration of As(III)-apt that resulted in the aggregation and redispersion behavior of (+)AuNPs, a dual-mode colorimetric aptasensor for As(III) determination was established. It was not only able to quantify As(III) sensitively over a ranges of As(III) concentrations, but also to selectively differentiate As(III) and eliminate false results from other control ions by dual-mode.

Multistage nucleic acid amplification induced nano-aggregation for 3D hotspots-improved SERS detection of circulating miRNAs

Circulating miRNAs in the blood can regulate disease development and thus indicate disease states via their various expression levels. For these reasons, circulating miRNAs constitute useful biomarkers, and an approach to the accurate detection of circulating miRNAs is attractive in the diagnosis and treatment of diseases. However, methods for clinical detecting of circulating miRNA that take both sensitivity and practicality into account are still needed. Therefore, we aimed herein to solve some inherent problems in the actual detection using a robust surface-enhanced Raman scattering (SERS) platform with integrated nucleic acid amplification and nanoparticle aggregation to construct 3D hotspots for improving performance of analyzing circulating miRNAs. After target recognition and initial signal amplification by DNAzyme, we observed that release triggered an open hairpin DNA on gold nanoparticles (AuNPs), which then promote AuNP aggregation, causing the accumulation of a large number of hotspots in three-dimention. The SERS biosensor achieved a better performance than the sandwich-type separation detection, with a low detection limit (0.37 fM) and a broad linear range (1 fM–10 nM) in liquids. This SERS platform can be used as a powerful tool for the detection of circulating miRNAs, and it can be used to improve the sensitivity and accuracy of various clinical-disease diagnoses.Graphical

Novel measurement method of determining PS nanoplastic concentration via AuNPs aggregation with NaCl.

Microplastics, or nanoplastics fragmented to sizes in the nanoscale, can easily penetrate living organisms as well as human organs, increasing the risk of toxicity. However, it is challenging to obtain the size of nanoplastics using thermal analysis methods such as pyrolysis gas chromatography/mass spectrometry or thermal desorption-gas chromatography/mass spectrometry, which are used to analyze nanoplastics. In this study, the coupling effect due to the aggregation of gold nanoparticles (AuNPs) was used to measure the concentration of polystyrene nanoplastics (PSNPs). Experiments were conducted to measure the concentration of PSNPs using an ultraviolet—visible spectrophotometer using the phenomenon that the color of the colloid changes when AuNPs are aggregated. The differences in absorbance before and after aggregation after the addition of NaCl were measured. As a result of the experiment, when 20 mM NaCl was added to the solution in which AuNPs and PSNPs were dispersed, the difference in absorbance before and after aggregation and the concentration of PSNPs exhibited high linearity. In addition, 350 and 880 nm-sized PSNPs could be distinguished from each other because of their different linearities. The concentration of PSNPs was measured easily and conveniently without requiring a skilled operator, expensive analytical equipment; additionally, the process was not time or labor intensive, and it was shown that particle size can be measured by distinguishing particles of different sizes.Electronic Supplementary MaterialSupplementary material is available in the online version of this article at 10.1007/s11814-022-1153-9.

A method for the controllable fabrication of optical fiber-based localized surface plasmon resonance sensors

Optical fiber-based Localized Surface Plasmon Resonance (OF-LSPR) biosensors have emerged as an ultra-sensitive miniaturized tool for a great variety of applications. Their fabrication by the chemical immobilization of gold nanoparticles (AuNPs) on the optic fiber end face is a simple and versatile method. However, it can render poor reproducibility given the number of parameters that influence the binding of the AuNPs. In order to develop a method to obtain OF-LSPR sensors with high reproducibility, we studied the effect that factors such as temperature, AuNPs concentration, fiber core size and time of immersion had on the number and aggregation of AuNPs on the surface of the fibers and their resonance signal. Our method consisted in controlling the deposition of a determined AuNPs density on the tip of the fiber by measuring its LSPR signal (or plasmonic signal, Sp) in real-time. Sensors created thus were used to measure changes in the refractive index of their surroundings and the results showed that, as the number of AuNPs on the probes increased, the changes in the Sp maximum values were ever lower but the wavelength shifts were higher. These results highlighted the relevance of controlling the relationship between the sensor composition and its performance.

In Situ Preparation of Plasmonic Gold Nanoparticle-Supramolecular Hydrogel Nanocomposites with Tunable Optical Properties: Correlating Theory and Experiments

Supramolecular plasmonic polymer nanocomposites are versatile soft materials that hold great promise for many bioapplications as they combine the functional properties of inorganic nanoparticles with the dynamic nature of the polymer matrix. Herein, we exploited the supramolecular chemistry and reducing properties of plant-derived gallic acid (GA) to drive the in situ formation of gold nanoparticles (Au NPs) into poly(vinyl alcohol) (PVA)–GA hydrogels. The size and shape of Au NPs in the plasmonic nanocomposites were tuned from 25 to 221 nm and from anisotropic to spherical, respectively, varying the Au3+ concentration. From experimental and theoretical simulation of the extinction spectra, it was possible to assess the change of the average refractive index of the surrounding Au NPs in two Au3+ concentration regimes. The changes of the chemical environment were also tested by Raman and infrared spectroscopy characterization. Furthermore, the viscoelastic behavior of the supramolecular PVA–GA hydrogel was also investigated for the plasmonic nanocomposites. At the highest concentration investigated, the formation of Au NP aggregates (dimers and trimers) was observed and rationalized with electrodynamic simulations. Finally, the surface-enhanced Raman spectroscopy properties were also analyzed using Rhodamine 6G, revealing the extraordinary capacity of these materials for their application as sensing platforms.

Greener approach for gold nanoparticles synthesis from fruit peel extract of Manilkara zapota: a fluorometric assay for determination of thiourea

A greener approach was applied for gold nanoparticles (AuNPs) synthesis via simple, non-hazardous and environment-friendly route utilizing the fruit peel extract of Manilkara zapota (sapodilla). The phytochemical screening of peel extract revealed that this extract act as a reductant and stabilizer concurrently for surface-functionalized AuNPs synthesis. The UV-Vis spectroscopy, FTIR, XRD, SEM-EDX and HR-TEM were employed to confirm the fabricated AuNPs. Moreover, a proficient fluorescence approach for the determination of thiourea (TU) based on fluorescence resonance energy transfer between rhodamine B (RB) and synthesized AuNPs, promotes fluorescence quenching. On addition of TU, the fluorescence of RB was recovered due to competitive adsorption between thiourea and RB on the surface of AuNPs, Which induces further aggregation of AuNPs. In optimal state, the linear relationship between the fluorescence recovery efficiency and TU concentration with the linear range from 0.02 − 1.0 ppm and the calculated detection limit was 0.017 ppm. The proposed fluorometric method was effectively utilized for TU detection in the actual sample with a good recovery percentage.

The development of a colorimetric biosensing assay for the detection of Helicobacter pylori in feces

As Helicobacter pylori (H. pylori) is closely related to the occurrence of gastric diseases such as chronic gastritis, peptic ulcer, and gastric cancer, early detection of H. pylori is an urgent need. In this study, oligonucleotide probes conjugated with gold nanoparticles (AuNPs) were used in combination with H. pylori-specific aptamers for the rapid detection of H. pylori in stool samples, which converted the method of detection from proteins to nucleic acids. Therefore, qualitative detection of H. pylori can be achieved by observing color changes through the aggregation (red to purple) or deaggregation (purple to red) of AuNPs, and further quantitative detection can be achieved through UV spectrometry. The detection limit of the colorimetric biosensing method is 25 CFU/mL (S/N = 3), which is favorably comparable to other reported detection methods. Compared with the existing detection methods for H. pylori, this colorimetric biosensing method has no limitations to the test subjects. All these features render the colorimetric biosensing assay a promising method for the clinical field detection of H. pylori.

Peptide amphiphile inspired self-assembled, ordered gold nanocomposites for improved sensitivity of electrochemical immunosensor: Applications in determining the total aflatoxin amount in food stuffs

In peptide amphiphile, The positively charged amino acid arginine can inspire the ordered self-assembly of gold nanocomposites (AuNPs), transfer positive charge to AuNPs, and weaken the aggregation of AuNPs by electrostatic repulsion, whereas hydrophobic fatty acid chains regulate the self-assembly of AuNPs through hydrophobic interaction, which may be a novel strategy to overcome disordered arrangement and aggregation of AuNPs to obtain an ultra-sensitive electrochemical immunosensor for determining the total aflatoxin amount. In this study, a peptide amphiphile (C14R5), composed of five arginine residues as the hydrophilic chain and myristic acid as the hydrophobic chain, inspired AuNPs to form monodispersed hollow raspberry-like AuNPs (rasAuNPs). rasAuNPs could captured and immobilized large amounts of aflatoxin antigens via the Au–S bonds, resulting in binding to more anti-aflatoxin antibodies. In the absence of aflatoxins, the enriched antigens bound to abundant antibodies, resulting in a low blank signal current. By contrast, in the presence of aflatoxins, enough antibodies could bind to the targets and less antibodies could recognize the antigens, increasing the detection signal intensity. Under the optimal conditions, the developed sensor demonstrated a wide linear range (0.13–29.06 pg mL−1) and a low limit of detection for total aflatoxins (0.05 pg mL−1) using a mixed standard (AFB1: AFB2: AFG1: AFG2 with a weight ratio of 1:1:1:1) in peanut, peanut milk, and maize powder samples. Hence, this novel strategy improves the sensitivity of electrochemical sensors and can be easily applied to detect other small molecule compound for the purpose of food safety.