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Foodborne pathogens contamination is one of the main sources of food safety problems. Although the existing detection methods have been developed for a long time, the complexity of food samples is still the main factor affecting the detection time and sensitivity, and the rapid separation and enrichment of pathogens is still an objective to be studied. Magnetic separation strategy based on magnetic nanoparticles (MNPs) is considered to be an effective tool for rapid separation and enrichment of foodborne pathogens in food. Therefore, this study comprehensively reviews the development of MNPs in the separation of foodborne pathogens over the past decade. First, various biorecognition reagents for identification of foodborne pathogens and their modifications on the surface of MNPs are introduced. Then, the factors affecting the separation of foodborne pathogens, including the size of MNPs, modification methods, separation strategies and separation forms are discussed. Finally, the application of MNPs in integrated detection methods is reviewed. Moreover, current challenges and prospects of MNPs for the analysis of foodborne pathogens are discussed. Further research should focus on the design of multifunctional MNPs, the processing of large‐scale samples, the simultaneous analysis of multiple targets, and the development of all‐in‐one small analytical device with separation and detection. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus (S. aureus) is a common foodborne pathogen that causes fever, vomiting, and other intestinal symptoms, and seriously affects human health and social safety. As a result, a reliable and sensitive detection technique for S. aureus must be developed. In this work, we proposed a sandwich assay on vancomycin functionalized magnetic beads (Van-MNPs) for S. aureus detection based on the specific binding between IgG and targets. The Van-MNPs were used as a tool for the separation of target bacteria. The biotin-modified IgG mediates binding between DNA nanoflowers (DNFs) and the target bacteria via interacting with streptavidin. The DNFs prepared by rolling circle amplification (RCA) were employed as a nano-container to enhance the capacity of biotins, and the streptavidin-horseradish peroxidase (SA-HRP) was loaded onto DNFs to catalyze the color change of TMB. Therefore, a colorimetric biosensor based on magnetic separation and rolling circle amplification was developed. The proposed methods for S. aureus detection showed a limit of detection (LOD) of 3.3 × 103 CFU/mL and excellent specificity. The biosensor has a certain reference value for the detection of S. aureus in juice. [ABSTRACT FROM AUTHOR]

A lectin magnetic separation (LMS) method for Staphylococcus aureus (S. aureus) was developed with the aim to improve the efficiency of magnetic nanoparticles and to expand the scope of bacterial recognition. Poly(ethylene glycol) (PEG)-mediated magnetic nanoparticles modified with streptavidin (MNP-PEG-SA) were synthesized and then applied to a two-step LMS based on the use of wheat germ agglutinin (WGA). Three specific methods for S. aureus detection (suitable for different requirements including detection time and sensitivity) were designed. The new LMS has improved anchoring efficiency (compared to two-step LMS methods) and requires a reduced number of magnetic particles. The Baird–Parker (B-P) method can detect S. aureus with a detection limit of 3 × 100 CFU·mL−1 within 15 h; the polymerase chain reaction (PCR) method can be finished within 4 h, with the lowest detection limit (LOD) of 3 × 102 CFU·mL−1. The LOD of HRP-pig IgG-based colorimetric method is 3 × 105 CFU·mL−1, and the method only lasts for 2 h. If combined with specific detection methods, it meets different needs for rapid detection of S. aureus. [ABSTRACT FROM AUTHOR]

Circulating tumour cells (CTCs) draw significant attention as a promising biomarker for cancer prognosis, status monitoring, and metastasis diagnosis. However, the concentration of CTCs in peripheral blood is usually extremely low, thereby requiring enrichment followed by isolation of CTCs prior to detection. An immunomagnetic separation is a promising tool for CTCs enrichment. In this study, a cost‐effective magnetic separation method, based on streptavidin–biotin complexation, was developed and the effects of magnetic beads' size in CTCs capture were compared. Magnetic nanobeads which were 25 nm in diameter lead to highest capture efficiency (82.2%) compared with 150 nm magnetic beads and 1 µm microbeads. Based on the streptavidin–biotin system, 25 nm magnetic nanobeads could capture model CTCs over 80% efficiency even at concentrations as low as ∼25 cells/mL that may represent the actual level of CTCs in peripheral blood of cancer patients. Furthermore, the isolated cells remained robust and healthy showing insignificant changes in morphology and behaviour when cultured for 24 h immediately after capture and isolation. The magnetic nanobeads based on streptavidin–biotin complexation showed promise for the easy and efficient capture and isolation of healthy CTCs for further diagnosis and analysis. [ABSTRACT FROM AUTHOR]

Ultrasensitive and rapid detection of low concentration of Escherichia coli O157: H7 (E. coli O157:H7) in food is essential for food safety and public health. In this study, A novel fluorescence signal amplification biosensor based on magnetic separation platform and red fluorescent carbon dots (R-CDs)-encapsulated breakable organosilica nanocapsules (BONs) for ultrasensitive detection of E. coli O157:H7 was established. Wulff-type boronic acid functionalized magnetic nanoparticles (MNPs@B–N/APBA) with broad-spectrum bacterial recognition ability were synthesized for the first time to recognize and capture E. coli O157: H7 in food samples. R-CDs@BONs labeled with anti- E. coli O157:H7 monoclonal antibody (mAb@R-CDs@BONs-NH 2) were used as the second recognition element to ensure the specificity for E. coli O157:H7 and form MNPs@B–N/APBA∼ E. coli O157:H7∼mAb@R-CDs@BONs-NH 2 sandwich complexes, followed by releasing R-CDs to generate amplified fluorescence response signals for quantitative detection of E. coli O157:H7. The proposed method had a limit of detection with 25 CFU/mL in pure culture and contaminated lettuce samples, which the whole detection process took about 120 min. This fluorescence signal amplification biosensor has the potential to detect other pathogens in food by altering specific antibodies. In this study, we establish a novel fluorescence signal amplification biosensor for ultrasensitive detection of E. coli O157:H7 in food. [Display omitted] • MNPs@B–N/APBA may broad-spectrum recognize and separate pathogen in food. • Spore-like CDs@BONs can effectively release CDs to amplify fluorescent signals. • The proposed biosensor can rapidly detect E. coli O157:H7 within 2 h in food. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rapid and direct detection of methicillin-resistant Staphylococcus aureus (MRSA) from sterile body fluids. • Magnetic separation enriched bacteria and identified specific protein peaks by MALDI-TOF MS. • The enrichment efficiency in cerebrospinal fluid and blood was greater than 80.95 % and 83.6 %. • The whole detection process could be completed within 1.5 h. • It breaks through the problems of long time and high technical requirements of traditional bacterial culture. As a result of the extensive use of antibiotics, methicillin-resistant Staphylococcus aureus (MRSA) has emerged, leading to serious clinical and epidemiological problems. This study established a rapid and accurate method for detection of MRSA in clinical samples. The MRSA detection procedure involved a magnetic separation technique and Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), and the characteristic peaks of proteins were compared to achieve the detection of MRSA. We treated PBS, blood and cerebrospinal fluid with MRSA, and identified it after short-term culture. The time and detection limit for identifying MRSA were determined. At the same time, we used the method to detect different proportions of mixed bacteria. The results revealed that the enrichment efficiency of Amp-MBs for MRSA in PBS, blood and cerebrospinal fluid was greater than 95 %, 80.95 % and 83.6 %, respectively. The whole detection process could be completed within 1.5 h. The negative and positive percent agreement of MRSA detection were 83 % and 95 %, respectively. In mixed bacterial samples, bacteria can be detected when the proportion of MRSA is greater than 50 %. Overall, this study provides an effective method for bacterial preconcentration and detection, which has high potential for rapid and sensitive diagnosis of MRSA infection [ABSTRACT FROM AUTHOR]

In this study, a new vancomycin (Van)-modified poly- l -lysine (PLL) magnetic bead (MB) technique was developed for isolation of gram-positive bacteria. The method combines magnetic separation with a multiplex PCR (mPCR) assay and gel electrophoresis for easy and rapid detection of Bacillus cereus. Vancomycin was used as a molecular ligand between the MB and the d -alanyl- d -alanine moieties on the cell wall surface of B. cereus. The PLL served as a flexible molecular tether between the MB and Van that reduced steric hindrance maintaining the biological activity of Van. The MB-PLL-Van capture nanoprobes exhibited excellent capture and isolation efficiency for B. cereus in spiked milk matrix samples without interference from the complex food matrix. The subsequent mPCR assay showed high specificity for the 4 target genes in B. cereus , the entFM , cesB , cer , and 16S rRNA genes, that were used to achieve efficient genotyping and detection. Under optimum conditions, the limit of detection reached 103 cfu/mL, with a dynamic range of detection at 103 to 107 cfu/mL in pure culture. Application of the MB-PLL-Van mediated mPCR assay for B. cereus in milk matrix samples achieved results similar to those of the pure culture. In addition, with a 6-h pre-enrichment of B. cereus that was spiked in milk matrix samples, the limit of detection reached 101 cfu/mL. The MB-PLL-Van mediated mPCR assay developed in this study could be used as a universal technology platform for the efficient enrichment and genotyping of gram-positive bacteria. [ABSTRACT FROM AUTHOR]

Pathogenic bacteria contamination poses a major threat to human health. The detection of low-abundance bacteria in complex samples has always been a knotty problem, and high-sensitivity bacterial detection remains challenging. In this work, a novel magnetic platform with high enrichment efficiency for L. monocytogenes was developed. The magnetic platform was designed by branched polyglutamic acid-mediated indirect coupling of cefepime on magnetic nanoparticles (Cefe-PGA-MNPs), and the specific enrichment of low-abundance L. monocytogenes in real samples was achieved by an external magnet, with a capture efficiency over 90%. A controllable and highly active platinum-palladium nanozyme was synthesized and further introduced in the magnetic nanoplatform for the construction of enzymatic colorimetric biosensor. The total detection time for L. monocytogenes was within 100 min. The colorimetric signals generated by labelled nanozyme were corresponding to different concentrations of L. monocytogenes , with a limit of detection (LOD) of 3.1 × 101 CFU/mL, and high reliability and accuracy (with a recovery rate ranging from 96.5% to 116.4%) in the test of real samples. The concept of the developed method is applicable to various fields of biosensing that rely on magnetic separation platforms. [Display omitted] • Broom-like magnetic platform captured > 90% of L. monocytogenes in real samples. • Size-controlled PdPt nanozyme demonstrated superior catalytic activity than HRP. • A signal acquisition and analysis system based on smartphone was established. • The LOD of L. monocytogenes was 3.1 × 101 CFU/mL. [ABSTRACT FROM AUTHOR]

Superparamagnetic nanoparticles (SMNPs) have been widely used in immunochromatographic assay (ICA) platform and achieved outstanding effects for overcoming the disadvantages of low sensitivity and poor matrix tolerance of ICA. The review presents the improvement of sensitivity and matrix tolerance of ICA due to immunomagnetic separation (IMS). Moreover, some novel magnetic separation technology, developed as new alternatives to IMS, based on non-antibody reagents are displayed to illustrate the novel concepts in various applications. SMNPs also act as a novel label for the signal output of ICA (SMNPs-ICA). This part focuses on examples of SMNPs-ICA based on optical and magnetic signal read modes to illustrate the advantage of SMNPs-ICA. At the same time, novel concepts in various sensors for magnetic reading and used as potential applications for screening tools are introduced. We also highlight the superiority of SMNPs aggregation-based, enzyme or nanozyme-based, and external magnetic field-based strategies for SMNPs-ICA. • The application and development of SMNPs-based IMS were reviewed. • Non-antibody reagents-based novel MS technology were introduced. • Optical and magnetic signal output modes of SMNPs-based ICA were reviewed. • Strategies to increase the sensitivity of SMNPs-ICA were introduced. • Potential challenges and trend were discussed for IMS and SMNPs-based ICA. [ABSTRACT FROM AUTHOR]

Highlights • Wheat germ agglutinin lectin (WGA) was applied as a recognition agent for S. aureus enrichment. • The use of LMS method resulted in a high enrichment efficiency even at low concentrations (100–102 CFU/mL) of S. aureus. • A quantitative and specific detection strategy based on dsDNA stabilized AuNPs was developed for S. aureus detection. • The detection limit of this method was 3.5 × 100 CFU/mL. Abstract A novel 2-step lectin-magnetic separation (LMS) method combined with gold nanoparticle (AuNPs) -based colorimetric system for specifically and quantitatively detecting S. aureus in blood samples was established. In this study, wheat germ agglutinin lectin from Triticum vulgaris (wheat) (WGA) was applied for the first time as a recognition agent in a 2-step magnetic separation method using magnetic nanoparticles (MNPs) for effective and low-cost bacteria enrichment. A quantitative detection strategy based on the long dsDNA amplicons stabilized with AuNPs against salt-induced aggregation was investigated. The 2-step LMS method resulted in a high enrichment efficiency even at low concentrations (100–102 CFU/mL) of S. aureus in pure culture and blood samples. The AuNPs-based colorimetric system was applied for quantitative detection of S. aureus with a limit of detection (LOD) at 3.5 × 100 CFU/mL. The complete process starting with the blood samples treatment, 2-step LMS, and AuNPs-based colorimetric detection took only 7 h. The low cost and sensitive 2-step LMS combined with AuNPs-based colorimetric detection holds considerable potential for early sepsis diagnosis. [ABSTRACT FROM AUTHOR]

Pathogenic bacteria are associated with high morbidity rates and present significant diagnostic challenges in terms of rapid detection. This study introduces a magnetic separation-based electrochemical biosensor for the detection of Methicillin-resistant Staphylococcus aureus (MRSA). Vancomycin (Van) was used to modify on the surface of polyethyleneimine (PEI) mediated MBs (MBs-PEI-Van) for separation and enrichment of MRSA. The MBs-PEI-Van shown a satisfactory stability and applicability with capture effective (CE) > 85% in both PBS and cerebrospinal fluid (CSF) samples. MXene@Au with controllable size of AuNPs was synthesized by a self-reduction method and employed to modify the glassy carbon electrode (GCE). Immunoglobulin G (IgG) was loaded onto the modified electrode to immobilize MRSA, and ferroceneboronic acid (Fc-BA) was used as a probe for quantitative determination. The differential pulse voltammetry (DPV) current was plotted against the concentration of MRSA from 3.8 × 101 to 3.8 × 107 CFU/mL with a limit of detection (LOD) of 3.8 × 101 CFU/mL. In addition, MRSA was successfully detected in spiked CSF samples with satisfactory recoveries (94.35–107.81 %) and validation results (RSD < 11 %). Overall, this study presents a promising method for the detection of MRSA, with the potential to be further developed into a universal pathogen detection method. [Display omitted] • The proposed MBs-PEI-Van shown capture effective > 85 % to MRSA in CSF samples. • The MXene@Au with controllable size of AuNPs was synthesized to modify electrodes. • The MXene@Au improved electrochemical response of Fc-BA probe. • Sensitive and selective detection of MRSA was realized in CSF samples. [ABSTRACT FROM AUTHOR]

In this study, we developed a PAMAM dendrimer-mediated biotin amplified magnetic separation method that was coupled with flow cytometry (FCM) for viable L. monocytogenes detection. PAMAM dendrimer-mediated biotin amplified magnetic separation strategy isolated more than 89.15% ± 1.75%  L. monocytogenes both in PBS solutions and in spiked lettuce samples at bacterial concentration below 10 4 CFU/mL. Propidium monoazide (PMA) treatment prior to PCR amplification eliminated the false-positive results from dead bacteria and detected viable L. monocytogenes sensitively and specifically. In this assay, a pair of specific primers was synthesized for the hly gene of L. monocytogenes that was modified with biotin and FAM (FITC) respectively. After PCR amplification, biotin and FAM (FITC) labeled amplicons were immobilized on the streptavidin coated magnetic microbeads, and the mean fluorescence intensity (MFI) of the microbeads was measured with flow cytometer. Combined PAMAM dendrimer-mediated biotin amplified magnetic separation with FCM assay for viable L. monocytogenes detection, and gave a limit of detection (LOD) as low as 3.5 × 10 1 CFU/mL in PBS and 3.5 × 10 2 CFU/g in spiked lettuce samples. Moreover, the method developed exhibited excellent specificity. Therefore, PAMAM dendrimer-mediated biotin amplified magnetic separation method coupled with FCM assay is a highly promising approach for L. monocytogenes detection. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cefepime was firstly introduced to construct magnetic capture probe. • Cefe-PEG-MNPs could reduce 75% of dosage consumption and 33.33% of incubation time compared with immuno-magnetic separation. • Sandwich assay integrated cefepime magnetic separation and enzymatic colorimetry. • The LOD of L. monocytogenes was 102 CFU/mL in lettuce sample. A novel sandwich assay for the detection of L. monocytogenes was designed based on antibiotic magnetic separation and enzymatic colorimetry. PEG-mediated cefepime functionalized magnetic nanoparticles (Cefe-PEG-MNPs) was reported for the first time to anchor L. monocytogenes cells with excellent bacterial capture capacity. The capture efficiency of L. monocytogenes in lettuce sample with high concentration (3.1 × 106 CFU/mL) was more than 73.8%. Anti- L. monocytogenes monoclonal antibody was adopted as the second anchoring agent to ensure the specificity for L. monocytogenes , which was co-modified with HRP on the surface of gold nanoparticles (AuNPs-HRP/mAb) to form AuNPs-HRP/mAb@ L. monocytogenes @Cefe-PEG-MNPs sandwich complexes, and TMB was added to generate a colorimetric signal. The limit of detection in contaminated lettuce, watermelon juice, and fresh meat samples were both 3.1 × 102 CFU/mL, and the whole assay takes about 110 min. Based on the above facts, the proposed method has great potential for rapid separation and detection of pathogenic bacteria in food. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes (L. monocytogenes), a typical foodborne pathogen, poses a serious threat to public health safety. This stimulates to develop a point-of-care testing (POCT) method to achieve rapid, sensitive detection of L. monocytogenes. In this study, polyethylene glycol (PEG) mediated ampicillin functionalized magnetic beads (Amp-PEG-MBs) was prepared successfully and it achieved high efficiency (>90%) and rapid (5 min) capture for L. monocytogenes at room temperature. The innovative combination of antibody (Ab), glucose oxidase (GOD) and graphene oxide (GO) prepared Ab@GO@GOD for the specific recognition of L. monocytogenes. Finally, Amp-PEG-MBs and Ab@GO@GOD were successfully assembled into Amp-PEG-MBs@ L. monocytogenes -Ab@GO@GOD sandwich structure which could catalyze the glucose, and the final detection results were recorded by a blood glucose meter (BGM). Magnetic separation (MS) combined with enzyme-catalyzed sensor (MS-Ab@GO@GOD-BGM) was successfully established to achieve the detection of L. monocytogenes in artificially contaminated juice within 66 min with the limit of detection was 101 CFU/mL. This sensor has potential for other pathogens detection by modifying specific antibodies. [Display omitted] • Sensor based on Magnetic separation and enzyme-catalyzed was established. • Point-of-care testing of L. monocytogenes in food sample was achieved. • The sensor can detect L. monocytogenes as low as 101 CFU/mL in food sample. • The integrated sensor enables highly-specific detection of L. monocytogenes. [ABSTRACT FROM AUTHOR]

[Display omitted] • The strategy of Amp-MBs-qPCR was established successfully. • Amp-MBs could identify and enrich bacteria of Listeria spp. with high CE. • The strategy could detect L. monocytogenes with high specificity. • The LOD of L. monocytogenes is 102 CFU/mL in spike milk sample within 2.5 h. Listeria monocytogenes (L. monocytogenes) is a typical food-borne pathogen which poses a serious threat to global public health. Achieving rapid and sensitive detection of pathogens in food is critical to solve food safety problems. In this work, ampicillin functionalized magnetic beads (Amp-MBs) were synthesized and used as a capture probe for detection of L. monocytogenes in milk sample combined with quantitative real-time polymerase chain reaction (qPCR) with high sensitivity and specificity. Amp, as a broad spectrum antibiotic was selected to identify bacteria of the Listeria spp. powerfully, and the hly as a specific gene of L. monocytogenes was selected to establish qPCR for accurate detection. At optimal conditions, the capture efficiency of Amp-MBs for L. monocytogenes (101-106 CFU/mL) and other bacteria of Listeria spp. (105 CFU/mL) was higher than 90 %. The limit of detection of Amp-MBs-qPCR strategy for L. monocytogenes was 101 and 102 CFU/mL in PBS and artificially contaminated milk within 2.5 h, respectively. And this strategy could detect L. monocytogenes from high concentration Listeria spp. with ascendant specificity. These results demonstrated that the Amp-MBs-qPCR strategy was successfully established and applied to the specific detection of L. monocytogenes in milk samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • The APBA to replace expensive recognition molecules such as antibiotics. • The CE of APBA-PEG-MNs to 106 CFU/mL of S. aureus is higher than 92%. • This method can detect S. aureus within 80 min. • This strategy can realize the detection of S. aureus in different samples. Staphylococcus aureus (S. aureus) is one of the pathogens that seriously endanger human health and are widespread in nature. Food poisoning incidents caused by S. aureus frequently break out. Therefore, it is significant that a rapid and accurate method is established for S. aureus detection. In this study, a strategy using magnetic separation combine with fluorescence analysis was proposed for S. aureus detection. Boric acid can selectively enrich compounds with cis -diol groups through a reversible esterification reaction, and has been widely used in the identification of sugars and glycosylated molecules. As a boric acid derivative, 3-aminophenylboronic acid (APBA) has the advantages of stability, low cost, easy synthesis, etc. Therefore, using APBA as a recognition molecule to prepare magnetic nanomaterials can achieve the enrichment of S. aureus. In order to reduce steric hindrance and ensure the dominant orientation of APBA, thus improving the enrichment performance of target bacteria. The polyethylene glycol (PEG) was used as a mediator to prepare PEG-mediated APBA functionalized magnetic nanomaterials (APBA-PEG-MNs). In addition, this study used FITC-pig IgG to label S. aureus because the Fc fragment of IgG to bind protein A on the surface of S. aureus and realized the detection of S. aureus by detecting fluorescence. Under the optimal experimental conditions, the capture efficiency of APBA-PEG-MNs for S. aureus with the concentration of 2.7 × 106 CFU/mL in spinach, juice and pool water spiked samples was 92.6%, 91.6%, 91.6%. The limit of detection of the strategy in spiked samples was 2.7 × 102 CFU/mL within 80 min. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus (S. aureus) is a common pathogen that can cause severe foodborne diseases. Therefore, the detection of S. aureus in food has been the focus of attention. In this study, a strategy for the detection of S. aureus using magnetic separation technology combined with colorimetry was proposed. Phenylboronic acid, as a compound that had been widely used in the identification of sugars and sugar-based molecules, can selectively enrich compounds with cis -diol groups through a reversible esterification reaction. Hence, 3-aminophenylboronic acid (APBA) could be used as a recognition molecule to capture bacteria, because there were a large amount of peptidoglycan and lipopolysaccharide on the surface of Gram-positive bacteria and Gram-negative bacteria. At the same time, there are few studies on the use of APBA as magnetic separation recognition molecule to enrich pathogenic bacteria. Therefore, we prepared APBA-functionalized magnetic beads (APBA-MBs) for pre-enrichment of S. aureus and an APBA-MBs based untargeted magnetic separation was constructed to replace the traditional targeted magnetic separation. In order to realize the output signal and guarantee the specificity for detecting S. aureus , we used HRP-pig IgG because the Fc fragment of IgG could bind the protein A on the cell wall of S. aureus. Finally, the tetramethylbenzidine (TMB) color development solution was occurred the chromogenic reaction under the action of the HRP enzyme. Under the optimal experimental conditions, the limit of detection (LOD) of the APBA-MBs combined with color reaction was 3.0 × 102 CFU/mL in pure culture, fruit juice, pool water and spinach. • Using APBA to replace expensive recognition molecules such as antibiotics. • The CE of S. aureus can reach 90%–100% in the range of 106 to 101 CFU/mL. • The strategy has good performance in different matrixes. • The strategy can realize the detection of S. aureus within 2 h. [ABSTRACT FROM AUTHOR]

Bacillus cereus (B. cereus) and Staphylococcus aureus (S. aureus) are two typical foodborne pathogens. In this study, we proposed a new strategy that combined antibiotic with magnetic beads (MBs) and multiplex PCR (mPCR) to detect B. cereus and S. aureus in juice sample with high sensitivity and specificity. Teicoplanin (TEI) is a glycopeptide antibiotic which can identify Gram-positive bacteria. The polyethylene glycol (PEG) and bovine serum albumin (BSA) double-mediated teicoplanin functionalized magnetic beads (TEI-BPBs) were prepared for separation of target bacteria, and the triplex PCR was used for specific detection by nuc , cesB and flic gene. Under optimal conditions, the TEI-BPBs showed a good ability to simultaneously capture S. aureus (>83%) and B. cereus (>81%). The TEI-BPBs-mPCR assay efficiently detected target bacteria even in the presence of 105 CFU/mL non-target bacteria. The results showed that the limit of detection (LOD) of B. cereus and S. aureus in PBS and juice sample could reach 100 CFU/mL within 4 h. Compared with conventional methods, this method has lower LOD and shorter detection time. The results demonstrate that the constructed TEI-BPBs capture probe and triplex PCR could be successfully applied to the rapid separation and detection of B. cereus and S. aureus or other Gram-positive pathogens in food samples. • The strategy of TEI-BPBs-mPCR was established successfully. • TEI-BPBs could identify and enrich Gram-positive pathogens. • The method could simultaneously detect B. cereus and S. aureus with high specificity. • Had lower LOD and shorter detection time than conventional PCR without MST. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus is a common foodborne pathogen that can cause a suppurative infection after eating contaminated food. Detection of S. aureus plays an important role in the food industry. In this study, a strategy for the detection of S. aureus using magnetic separation (MS) technology combined with rolling circle amplification (MS-RCA) was proposed. The strategy used antibiotics to capture bacteria and employed RCA products as signal output probes. Vancomycin (Van), as a commonly used antibiotic, can recognize peptidoglycan on the cell wall of Gram-positive bacteria and can effectively identify target bacteria. Therefore, we prepared BSAylated-Van functionalized magnetic beads (Van-MBs) for the pre-enrichment of S. aureus. To ensure the selectivity of this method, we used biotin-pig IgG to bind S. aureus. In addition, to amplify the output signal of the MS-RCA strategy, we introduced streptavidin (SA) and successfully obtained the Van-MBs@ S. aureus @biotin-pig IgG@SA@biotin-RCA probe complex and used the biotin-avidin-system (BAS) by combining magnetic separation technology and RCA technology to realize the enrichment and specific detection of S. aureus. Furthermore, by optimizing the experimental conditions such as the magnetic separation time and the amount of Van-MBs, the detection performance of this method was improved. Under the optimal conditions, the detection limit of this method for S. aureus was 3.3 × 102 CFU/mL in fruit juice, and it was less affected by other bacteria. [Display omitted] • RCA probe can produce amounts of ssDNA, resulting fluorescence signals amplification. • The method could be applied to the detection of Gram-positive bacteria. • The method is sensitive, specific, and simple for S. aureus detection. [ABSTRACT FROM AUTHOR]

[Display omitted] • MS-mPCR was developed to accurately distinguish MRSA from S. aureus. • Sensitivity of developed MS-mPCR was two orders of magnitude higher than regular mPCR. • MS-mPCR has excellent performance for MRSA detection in blood and cerebrospinal fluid. Due to the massive use of antibiotics, clinical highly pathogenic bacteria methicillin-resistant Staphylococcus aureus (MRSA) have emerged. Given its non-uniform drug resistance, it brings numerous difficulties for clinical diagnostic tests. This study aimed to establish a fast and accurate method to detect MRSA in hospital samples. In order to shorten the detection time and eliminate the influence of matrix on the detection results, so as to improve the detection sensitivity. In this study, magnetic separation (MS) technology was used for pre-treatment of samples, and triplex PCR was established using mecA , nuc and flic genes to realize the detection of MRSA. The results showed that the lowest detection limit of MRSA in blood samples and cerebrospinal fluid could reach 102 CFU/mL and 103 CFU/mL. Therefore, the MS technology combined with triplex PCR assay established in this study is expected to provide a strong basis for the detection of MRSA in hospital samples. [ABSTRACT FROM AUTHOR]

Sepsis caused by bacteria has high morbidity and mortality, and it is neccerssay to establish a fast, convenient, and facility assays for detection of bacteria. In this study, we have developed established a simple, rapid, and ultrasensitive vancomycin (Van) and dendrimer nanoparticles-based method to isolate and detect bacteria in human blood using a multivalent binding strategy. The proposed Bio-den-Van multivalent capture nanoplatform combined with m-qPCR for simultaneous detection of two kinds of bacteria was demonstrated with rapid 2 min bacteria isolation with a linear range at 3.2 × 101–3.2 × 106 CFU·mL-1 for L. monocytogenes and 4.1 × 101–4.1 × 106 CFU·mL-1 for S. aureus , respectively. The limit of detection (LOD) for simultaneous detection of L. monocytogenes and S. aureus were 32 and 41 CFU·mL-1 in spiked human blood samples, respectively. Other bacteria had an insignificant interference with the test results. This Bio-den-Van multivalent capture nanoplatform combined with m-qPCR detection exhibited rapid, high sensitivity and specificity in simultaneous detection of various bacteria. To our knowledge, this is the first time that Bio-den-Van multivalent capture nanoplatform was used with Van as a recognition molecule for the simultaneous capture and subsequent detection of two bacteria from spiked human blood sample. This method holds great potential for future clinical applications. Image 1 • Van functionalized PAMAM to generate multivalent interactions between specific multiple-ligand-receptor and capture target bacteria from blood samples. • It is the first time that used Van as a recognition molecule for Gram-positive bacteria simultaneous detection. • The LOD of L. monocytogenes and S. aureus was 32 and 41 CFU mL−1 in spiked human blood. [ABSTRACT FROM AUTHOR]