Complex Food Matrix Research Articles

Detection of neonicotinoids in agricultural products using magnetic molecularly imprinted polymers-surface enhanced Raman spectroscopy

In this paper, magnetic molecularly imprinted polymers-surface-enhanced Raman spectroscopy (MMIPs-SERS) for rapidly analyzing acetamiprid and thiacloprid in agricultural products has been firstly developed. The magnetic imprinted polymers were obtained by polymerizing the imprinted layers on the surface of magnetic nanoparticles. The polymers were detailed characterized by using series of analytical techniques, and their adsorption and recognition performance were validated by adsorption tests. The results showed that the magnetic molecularly imprinted polymers possessed typically core-shell structure and exhibited class-specific recognition, fast adsorption saturation (only 1 min), and good magnetic separation performance towards targets. The adsorption and desorption conditions for MMIPs-SERS detection system were carefully investigated. Under optimum conditions, the good linear detection range of 1∼20 μg/g with LODs of 23.7–68.8 ng/g for acetamiprid and thiacloprid in peach and pear samples was obtained. Through the reusable and spiked experiments, the developed MMIPs-SERS method based on Au NPs as enhanced substrate was validated to be highly sensitive, accurate, efficient and applicable in analyzing neonicotinoids from pear and peach samples. This study provided a rapid and simple detection method for neonicotinoids with effective separation and detection properties based on the synergistic effect of imprinted polymers and SERS. More importantly, this developed method have good application potential in rapid analyzing field for neonicotinoids due to the amazing rapid adsorption time for extracting targets from complex food matrix (only 1 min).

Voltammetric determination of doxycycline in feedstock using modified carbon screen-printed electrode.

In this work, we describe the development of an electrochemical sensing platform that employs electrochemically reduced graphene oxide (ErGO) and gold (Au) deposited on a screen-printed carbon electrode (SPCE) to synthesize Au/ErGO/SPCE for the determination of the antibiotic drug doxycycline (DC). A modified Hummer's approach was adopted to initially prepare graphene oxide, which was then characterized by using powder XRD, FTIR, and UV spectroscopy before being utilized for modification on SPCE. Cyclic voltammetry was performed to form ErGO on SPCE to give ErGO/SPCE followed by electrodeposition of gold to get a final modified electrode Au/ErGO/SPCE. The effect of experimental conditions, like scan rate and pH on the electrochemical behavior of DC for Au/ErGO/SPCE, was evaluated. Square wave voltammetry (SWV) and cyclic voltammetry (CV) measurements were used to assess the electro-oxidation of DC on Au/ErGO/SPCE, and the electrochemical reaction conditions were also optimized. Furthermore, Au/ErGO/SPCE-based electrochemical sensors showed good recovery and high accuracy for DC determination in the complex food matrix and blood serum. The limit of detection (LOD), the limit of quantification (LOQ), and the linear calibration range of DC on Au/ErGO/SPCE under optimum experimental conditions were 0.124µm, 0.415µm, and 1-100µm respectively, with high sensitivity of 0.194 μA μM-1cm-2. Finally, the proposed electrochemical sensing platform was effectively used to determine low DC concentrations in real samples such as chicken flesh and blood serum, indicating its wide range of applications in quality control.

Aptamers for mycotoxin recognition in food: Recent advances and future considerations

The contamination of mycotoxin in food has posed a serious threat to human health and safety. Accurate detection of mycotoxins provides a strong guarantee for food safety. Aptamers with excellent recognition capacity to mycotoxins have gained growing attention because of their high binding affinity, high specificity and low cost. They are commonly generated by an in vitro selection procedure called SELEX. However, the existing performance of mycotoxin aptamers are not good enough in complex food matrix, and the success rate of SELEX still need to be improved. The employment of efficient SELEX strategies for the generation of better mycotoxin aptamers is significantly important. This article has reviewed different SELEX approaches conducted for mycotoxin aptamer generation. Furthermore, the properties of various mycotoxin aptamers have been discussed. Finally, challenges and future considerations for mycotoxin aptamer selection are summarized, and their strengths and limitations in food safety application are highlighted.

On-Demand Portable Paper-Based Electrospray Ionization Mass Spectrometry for High-Sensitivity Analysis of Complex Samples.

Paper spray ionization has been demonstrated to be the most promising substrate-based source, but this technique suffers from the low desorption efficiency of target compounds and poor portability. In the current study, we describe a portable paper-based electrospray ionization (PPESI) in which a piece of triangle paper and adsorbent are packed sequentially into a modified disposable micropipette tip. This source not only captures the feature of paper spray and adsorbent for highly efficient suppression of sample matrixes for target compound analysis but also takes advantage of a micropipette tip to prevent spray solvent from rapid evaporation. The performance of developed PPESI depends on the type and amount of packed adsorbent, paper substrate, and spray solvent and applied voltage. Moreover, by contrast to other related sources, the analytical sensitivity and the spray duration of PPESI in tandem with MS have been improved by factors of 2.8-32.3 and 2.0-13.3, respectively. Based on its high accuracy (>96%) and precision (less than 3% relative standard deviation), the PPESI coupled to a mass spectrometer has been used to determine diverse therapeutic drugs and pesticides in complex biological (e.g., whole blood, serum, and urine) and food (e.g., milk and orange juice) matrixes, and the limits of detection and quantification were 2-4 pg mL-1 and 7-13 pg mL-1, respectively. Taking the portability, high sensitivity, and repeatability, the technique may be a promising alternative for complex sample analysis.

Unlocking the bioactivity of meat proteins: Comparison of meat and meat hydrolysate via simulated gastrointestinal digestion

Understanding the functional attributes of meat proteins is crucial for determining their nutritional benefits. Depending on the form in which meat proteins are available, the digestive process can release peptides which are valuable for nutrition and may also possess bioactive properties, affecting physiology. Liquid chromatography – mass spectrometry (LC-MS) was used to quantitatively compare the molecular peptide features (representing non-redundant peptides), during the different stages of a simulated gastrointestinal digestion process of a minimally processed powdered meat and its enzymatically produced hydrolysate. Results from a principal component analysis (PCA) indicated that the hydrolysate did not undergo extensive additional digestion whereas the powdered meat was digested both at the gastric and in the intestinal phases. Bioactive peptide sequence prediction identified the meat hydrolysate but not the meat powder as the only source of exact and partial bioactive matches in the angiotensin-I converting enzyme and dipeptidyl peptidase IV inhibition categories. Also, a higher source of cryptides (encrypted bioactive peptides), indicated that meat hydrolysates are potentially a better substrate for the release of these enzyme inhibitory peptides. These observations thus suggest that pre-digestion of a complex food matrix such as meat, may enhance its bioavailability following oral consumption early in the digestion process. SignificanceThis work highlights enzymatic hydrolysis of meat proteins prior to ingestion allows for potentially higher bioavailability of bioactive peptides that inhibit angiotensin-I converting enzyme and dipeptidyl peptidase IV, thus possibly aiding high blood pressure and type 2 diabetes management.

Internal reflectance cell fluorescence measurement combined with multi-way analysis to detect fluorescence signatures of undiluted honeys and a fusion of fluorescence and NIR to enhance predictability

Honey is a complex food matrix that contains diverse polyphenolic compounds. Some phenolics exhibit fluorescence signatures which can be used to evaluate honey quality, and authenticity and to determine botanical origin. Mānuka honey contains two unique fluorescence markers: Leptosperin (MM1) and LepteridineTM (MM2) that are derived from Leptospermum scoparium nectar. Fluorescence measurement of supersaturated solutions such as undiluted honeys can be challenged by complex inner filter effects. The current study shows the ability of internal reflectance cell fluorescence measurement and multi-way analysis to detect fluorophores in undiluted honeys. This study scanned honeys from different geographic districts generating excitation emission matrices (250–400/300–600 nm), and by near infrared (NIR) hyperspectral camera (547–1701 nm). PARAFAC and tri-PLS could track two fluorescence markers: MM1 (R2 = 0.82 & RMSEP = 138.65) and MM2 (R2 = 0.82 & RMSEP = 2.75) from undiluted honey fluorescence data with > 80 % accuracy. Classification of mono-floral, multi-floral and non-mānuka honeys achieved 90 % overall accuracy. Fusion of fluorescence data at ƛex 270 & 330 nm and NIR hyperspectral data combined with multi-block PLS analysis enhances predictability of fluorescence markers further. The study revealed the potential of internal reflectance cell fluorescence measurement combined with chemometrics and data fusion for rapid evaluation of honey quality and botanical origin.

Chemiluminescence and fluorescence biosensors for food application: A review

Nowadays, the analysis of food is of high concern in terms of quality and safety. Analysis of food samples becomes tedious when complex food matrixes cause interference during analysis. Optical biosensors based on chemiluminescence (CL) and fluorescence (FL) detection have been dedicated to different food analysis over the last few decades. These CL and FL-based biosensors offer several merits over routinely used conventional methods in terms of sensitivity and selectivity. They also facilitate the ease of analysing different samples with minimal sample preparation. This article compiles data from CL and FL-based biosensing in various food samples with varied sample matrices. The main focus of this article is to provide brief introduction to the topic, systematize current literature on CL and FL-based biosensors for food analysis and discuss critical challenges as well as future prospects in this field.

Molecularly imprinted ratiometric fluorescence detection of tetracycline based on its fluorescence enhancement effect caused by tungsten trioxide quantum dots

This paper reports a novel probe developed based on the tungsten trioxide quantum dots (WO3-x QDs) and molecularly imprinted polymers for the detection of trace tetracycline (TC) in the complex food matrix. Tungsten ion (W6+) in WO3-x QDs has a fluorescence enhancement effect on TC, and TC has a fluorescence quenching effect on WO3-x QDs. The blue emission of the WO3-x QDs (λem = 470 nm) as a reference and the yellow emission of the TC (λem = 550 nm) as a response were utilized for the ratiometric fluorescence detection. In order to improve its selectivity, the molecular imprinting technology was combined to construct molecularly imprinted ratiometric fluorescent probes (MIRFPs). Therefore, the MIRFPs can not only selectively detect TC, but also realize the visual detection from blue to yellow. Under the optimal conditions, the linear ranges of 0.01 ∼ 10.0 μmol/L and 20.0 ∼ 80.0 μmol/L were obtained with the limits of detection of 3.23 nmol/L and 6.37 μmol/L, respectively. Furthermore, the MIRFPs had been successfully applied to the detection of TC in milk and eggs. The satisfactory recoveries were in the range of 92.7 ∼ 102.9 % with relative standard deviations (RSD, n = 3) below 1.59 %. This work offers a good strategy for the detection of food hazards.

Rapid and label-free Listeria monocytogenes detection based on stimuli-responsive alginate-platinum thiomer nanobrushes.

In this work, we demonstrate the development of a rapid and label-free electrochemical biosensor to detect Listeria monocytogenes using a novel stimulus-response thiomer nanobrush material. Nanobrushes were developed via one-step simultaneous co-deposition of nanoplatinum (Pt) and alginate thiomers (ALG-thiomer). ALG-thiomer/Pt nanobrush platform significantly increased the average electroactive surface area of electrodes by 7 folds and maintained the actuation properties (pH-stimulated osmotic swelling) of the alginate. Dielectric behavior during brush actuation was characterized with positively, neutral, and negatively charged redox probes above and below the isoelectric point of alginate, indicating ALG-thiomer surface charge plays an important role in signal acquisition. The ALG-thiomer platform was biofunctionalized with an aptamer selective for the internalin A protein on Listeria for biosensing applications. Aptamer loading was optimized and various cell capture strategies were investigated (brush extended versus collapsed). Maximum cell capture occurs when the ALG-thiomer/aptamer is in the extended conformation (pH > 3.5), followed by impedance measurement in the collapsed conformation (pH < 3.5). Low concentrations of bacteria (5CFUmL-1) were sensed from a complex food matrix (chicken broth) and selectivity testing against other Gram-positive bacteria (Staphylococcus aureus) indicate the aptamer affinity is maintained, even at these pH values. The new hybrid soft material is among the most efficient and fastest (17min) for L. monocytogenes biosensing to date, and does not require sample pretreatment, constituting a promising new material platform for sensing small molecules or cells.

Synthesis of dummy-template molecularly imprinted polymers as solid-phase extraction adsorbents for N-nitrosamines in meat products

In this study, the dummy template molecularly imprinted polymers were firstly prepared by precipitation polymerization method using benzhydrol, 5-nonanol and N-formylpyrrolidine as template molecules and methacrylic acid as functional monomer. The obtained polymers were characterized and showed spherical particles with loose and porous surface. The dynamic and static adsorption experiments indicated that the polymers exhibited large adsorption capacity, high adsorption efficiency and specific recognition ability towards N-nitrosamines. The parameters of solid phase extraction process were carefully optimized. Under the optimized conditions, the solid phase extraction process based on dummy molecularly imprinted polymers coupled with high performance liquid chromatography-tandem mass spectrometry for analyzing N-nitrosamine in various processed meat products was established. This proposed method showed good linearity (R2 ≥ 0.9985), and the limits of detection and the limits of quantification were in the range of 0.03–0.65 ng/g and 0.1–1.95 ng/g, respectively. With three spiked concentrations (5, 10, and 20 ng/g), satisfactory recoveries (61.0–105.2 %) were also obtained with relative standard deviations between 1.20 and 9.76 %. Those results demonstrated that the method for N-nitrosamine possessed the advantages of high selectivity, good reproducibility and high sensitivity, providing great convenient method for enriching and detecting N-nitrosamine in complex food matrix.

CRISPR/Cas12a-based magnetic relaxation switching biosensor for nucleic acid amplification-free and ultrasensitive detection of methicillin-resistant Staphylococcus aureus

Herein, we develop a CRISPR/Cas12a-based magnetic relaxation switching (C-MRS) biosensor for ultrasensitive and nucleic acid amplification-free detection of methicillin-resistant Staphylococcus aureus (MRSA) in food. In this biosensor, mecA gene in MRSA was recognized by CRISPR-RNA, which will activate the trans-cleavage activity of Cas12a and release the fastened alkaline phosphatase (ALP) on the particle. The freed ALP can then use to hydrolyze substrate to produce ascorbic acid that trigger the click reaction between magnetic probe. The transverse relaxation time of the unbound magnetic probe can be measured for signal readout. By incorporating collateral activity of CRISPR/Cas12a, on-particle rolling circle amplification, and ALP-triggered click chemistry into background-free MRS, as low as 16 CFU/mL MRSA can be detected without any nucleic acid pre-amplification, which avoids carryover contamination, but without compromising sensitivity. Moreover, this C-MRS biosensor could distinguish 0.01% target DNA from the single-base mutant. Recovery in eggs, milk and pork ranged from 75% to 112%, 82%–104%, and 81%–91%, respectively, revealing its satisfactory accuracy and applicability in the complex food matrix. The developed C-MRS biosensor fleshes out the CRISPR toolbox for food safety and provides a new approach for the sensitive and accurate detection of foodborne drug-resistant bacteria.

Flavor Profiling Using Comprehensive Mass Spectrometry Analysis of Metabolites in Tomato Soups.

Trained sensory panels are regularly used to rate food products but do not allow for data-driven approaches to steer food product development. This study evaluated the potential of a molecular-based strategy by analyzing 27 tomato soups that were enhanced with yeast-derived flavor products using a sensory panel as well as LC-MS and GC-MS profiling. These data sets were used to build prediction models for 26 different sensory attributes using partial least squares analysis. We found driving separation factors between the tomato soups and metabolites predicting different flavors. Many metabolites were putatively identified as dipeptides and sulfur-containing modified amino acids, which are scientifically described as related to umami or having "garlic-like" and "onion-like" attributes. Proposed identities of high-impact sensory markers (methionyl-proline and asparagine-leucine) were verified using MS/MS. The overall results highlighted the strength of combining sensory data and metabolomics platforms to find new information related to flavor perception in a complex food matrix.

Biocathodes reducing oxygen in BPE-ECL system for rapid screening of E. coli O157:H7

After discovery of electron transfer from bacteria, most bacteria known to be electrochemically active are utilized as a self-regenerable catalyst at the anode of microbial fuel cells (MFCs). However, the reverse phenomenon, cathodic catalysts is not so widely researched. This present study demonstrated that E. coli O157:H7 was electrochemically active, and it was able to catalyze oxygen reduction at the cathode of bipolar electrode (BPE). Applying a constant potential to the BPE, E. coli O157:H7 can catalyze electrochemical reduction of O2, decrease the overpotential of O2 reduction at the cathode, which in turn generates an electrochemiluminescence (ECL) reporting intensity change at the anode. Significantly, a majority of food matrix does not exhibit catalytic activity for electrochemical reduction of O2. Meanwhile, due to the physically separation of two poles of closed BPE, complex food matrix at the cathode does not interfere with the ECL reaction at the anode. Therefore, the effect of food matrix is negligible when measuring E. coli O157:H7 levels in food. A low detection limit of 10 CFU mL−1 E. coli O157:H7 could be identified within 1 h. Thus, biocathodes reducing oxygen in BPE-ECL system has shown excellent characteristics in the field of rapid detection of electroactive bacteria in food.

Biomimetic functional material-based sensors for food safety analysis: A review

Food may be contaminated by various hazardous substances in all stages of the food supply chain, which may pose a wide variety of human health risks. The ability to construct sensors capable of highly selective analysis in complex food matrix could offer strong support for guaranteeing food safety. The design, preparation, and introduction of biomimetic functional materials as antifouling materials or recognition receptors provide new ideas for further improvement of the anti-interference and specificity of sensory system. Herein, biomimetic functional materials commonly used in sensor preparation, including biomimetic antifouling materials [poly(ethylene glycol), zwitterionic polymers, and synthetic antifouling peptides] and biomimetic recognition receptors (molecularly imprinted polymers, aptamers, and mimetic recognition peptides) are reviewed. The mechanisms, advantages, limitations of these biomimetic functional materials and the applications of biomimetic functional material-based sensors in food safety analysis are summarized. Finally, the challenges and prospects of sensors based on biomimetic functional materials are analyzed.

Development of a new concentration method for Hepatitis A virus detection (ISO 15216–2:2019) in Manila clams (Ruditapes philippinarum)

Hepatitis A virus (HAV) is an important agent of foodborne human viral illness and continues to be a public health concern. Currently, the RT-qPCR method (ISO 15216–2:2019) is the gold standard for HAV detection in food. However, because of the complex food matrix and low virus titers in food, there is a need for effective methods for virus enrichment. In this study, we developed a sensitive method for HAV detection in Manila clams and added polyethylene glycol (PEG) precipitation procedures on the ISO 15216–2:2019 standard method (SM). The results showed that the recovery rates were significantly higher with more process control virus (MS2) added in the improved method (IM) than in SM, from 0.24% to 1.34% and 3.22%–13.91% respectively. The detection sensitivity of the new method (101.5 CCID50/mL) in IM was lower than that of the standard method (102.5 CCID50/mL) in SM, with recovery rates of 6.38% and 2.45%, respectively. The positive detection rate of HAV (4.48%) in IM was significantly higher than that in the standard method (0.75%). The new method is a rapid and suitable method for concentrating and detecting HAV from Manila clams. This approach has important applications in HAV monitoring and detection to ensure the safety of Manila clams for human consumption.

Covalent organic framework@Ti3C2Tx composite as solid phase microextraction coating for the determination of polycyclic aromatic hydrocarbons in honey samples

In this study, covalent organic framework@MXene (COF@Ti3C2Tx) composites were synthesized and employed as solid phase microextraction coatings for isolation of polycyclic aromatic hydrocarbons (PAHs) from honey samples. The developed composites possessed unique structural characteristics and multiple interactions (π-π and hydrophobic interaction, etc.), which provided them with excellent extraction capacity towards the targeted PAHs. Under optimized conditions, the resultant COF@Ti3C2Tx-coating fiber-based HS-SPME/GC-FID method exhibited a wide linear range (2.0–2000 ng g−1), good linearities (r > 0.9964), and low limits of detection (0.20–0.60 ng g−1). The recoveries of PAHs in the honey samples were in the range of 73.2–112%, with RSDs less than 9.4%. In addition, the findings showed that the composite-based fiber offers a long lifetime, high enhancement factors (483–598), and excellent fiber-to-fiber reproducibility (RSDs <10.5%, n = 3). This work not only details the development of a multi-functional composite, but it also presents an effective strategy for the determination of trace PAHs in complex food matrix.

Characterisation of catechins and their oxidised derivatives in Ceylon tea using multi-dimensional liquid chromatography and high-resolution mass spectrometry

Tea is a complex food matrix comprising of many structurally diverse compounds, of which catechins and their oxidised derivatives are of particular interest due to their nutritional functionality. However, these catechins and derivatives exist in various isomeric forms with few or no pure standards available, rendering their analysis challenging. A method combining multi-dimensional liquid chromatography (MDLC) and high-resolution mass spectrometry (HRMS) was developed for the characterisation of these compounds using Ceylon tea as a model. Based on a Plackett–Burman (PB) design, flow rate and initial methanol percentage were identified as the most significant factors (p < 0.05) affecting chromatogram coverage and resolution (Rs) for comprehensive two-dimensional LC (LCxLC) and heart-cutting two-dimensional LC (LC-LC) respectively. Central composite design (CCD) was then applied using these parameters for method optimisation and to identify second-order relationships between screened parameters. The optimised LCxLC (flow rate: 2.18 mL/min and initial methanol percentage: 28.0%) and LC-LC (flow rate: 0.86 mL/min and initial methanol percentage for different cuts: A- 10.0%; B- 15.8%; and C- 18.7%) methods were applied to the analysis of Ceylon tea samples from seven regions of Sri Lanka and demonstrated an improved separation of co-eluting isomeric compounds. Finally, with the mass spectral information from HRMS, a total of 31 compounds (eight monomers, 17 dimers, five trimers and one tetramer) were detected and putatively identified in Ceylon tea.

Optimization of a sample preparation workflow based on UHPLC-MS/MS method for multi-allergen detection in chocolate: An outcome of the ThRAll project

Developing reliable methodologies for detecting and quantifying allergens in processed food commodities is crucial to support food business operators in allergen risk assessment and properly implementing precautionary allergen labels whenever required to safeguard the health of allergic consumers. Multiple Mass Spectrometry (MS) methods have been developed so far and applied for single and multi-allergen detection in foods, generating a heterogeneous literature on this topic, with little attention paid to the extraction and the digestion steps, crucial in delivering accurate allergen measurements.This investigation carried out within an international consortium specifically built up to convey a prototype MS based reference method, reports on the first part of the method development, namely the optimization of the sample preparation protocol for six allergens detection (cow's milk, hen's egg, soy, peanut, hazelnut, and almond) in chocolate. The latter was chosen as model complex food matrix, having a high lipid and polyphenol content.Different steps of the sample preparation protocol have been taken into consideration: (i) sampling, (ii) composition of the extraction buffer, (iii) protein purification, (iv) protein enzymatic digestion, (v) peptide purification and pre-concentration, and some experiments were carried out by two independent laboratories and two different MS platforms to provide a first assessment of the robustness of the method under development. Fifty target peptides were monitored in multiple reaction monitoring mode and validated in different laboratories to trace the six allergenic ingredients in the incurred chocolate and the best performing protocol for sample preparation was identified. This work paves the way of the forthcoming full analytical validation of a prototype reference method for MS-based allergen quantification.

Monitoring and Characterization of Milk Fouling on Stainless Steel Using a High-Pressure High-Temperature Quartz Crystal Microbalance with Dissipation.

Fouling at interfaces deteriorates the efficiency and hygiene of processes within numerous industrial sectors, including the oil and gas, biomedical device, and food industries. In the food industry, the fouling of a complex food matrix to a heated stainless steel surface reduces production efficiency by increasing heating resistance, pumping requirements, and the frequency of cleaning operations. In this work, quartz crystal microbalance with dissipation (QCM-D) was used to study the interface formed by the fouling of milk on a stainless steel surface at different flow rates and protein concentrations at high temperatures (135 °C). Subsequently, the QCM-D response was recorded during the cleaning of the foulant. Two phases of fouling were identified. During phase-1, the fouling rate was dependent on the flow rate, while the fouling rate during phase-2 was dependent on the flow rate and protein concentration. During cleaning, foulants deposited at the higher flow rate swelled more than those deposited at the lower flow rate. The composition of the fouling deposits consisted of both protein and mineral species. Two crystalline phases of calcium phosphate, β-tricalcium phosphate and hydroxyapatite, were identified at both flow rates. Stratification in topography was observed across the surface of the QCM-D sensor with a brittle and cracked structure for deposits formed at 0.2 mL/min and a smooth and close-packed structure for deposits formed at 0.1 mL/min. These stratifications in the composition and topography were correlated to differences in the reaction time and flow dynamics at different flow rates. This high-temperature application of QCM-D to complex food systems illuminates the initial interaction between proteins and minerals and a stainless steel surface, which might otherwise be undetectable in low-temperature applications of QCM-D or at larger bench and industrial scales. The methods and results presented here have implications for optimizing processing scenarios that limit fouling formation while also enhancing removal during cleaning.

Split aptamer remodeling-initiated target-self-service 3D-DNA walker for ultrasensitive detection of 17β-estradiol

DNA walker machines, as one of the dynamic DNA nanodevices, have attracted extensive interest in the field of analysis due to their inherent superiority. Herein, we reported a split aptamer remodeling-initiated target-self-service 3D-DNA walker for ultrasensitive, specific, and high-signal-background ratio determination of 17β-estradiol (E2) in food samples. Two split probes (STWS-a and STWS-b) were rationally designed that can undergo structural reassembled to serve as walking strands (STWS) under the induction of the target. Meanwhile, an intact E6-DNAzyme region was formed and activated at the tail of STWS. The activated E6-DNAzyme then continuously drives the 3D-DNA walker for signal amplification and specific detection of E2. Under optimal conditions, the proposed DNA walker-based biosensor exhibited excellent linearity in the range of 1 pM to 50 nM with a low limit of detection (LOD) of 0.28 pM, and good precision (2.7%) for 11 replicate determinations of 1 nM of E2. Furthermore, the developed DNA walker-based biosensor achieved excellent sensitive analysis of E2 in the complex food matrix with recoveries of 95.6–106.5%. This newly proposed split aptamer-based strategy has the advantages of ultrasensitive, high signal-to-background ratio, and high stability. Noteworthy, the successful operation of the DNA walker initiated by the split aptamer expands the principles of DNA walker design and provides a universal signal amplification platform for trace analysis.