One-Step Purification of IgE Epitope-Specific Antibody Using Immunomagnetic Beads and Highly Sensitive Detection of Bovine β-Lactoglobulin for the Prediction of Milk Allergenicity in Foods

Bovine β-lactoglobulin (BLG) is a common allergen found in milk, and the immunoglobulin E (IgE) epitope plays a crucial role in cow milk allergy. Therefore, targeting the IgE epitope could be useful in accurately detecting BLG and assessing its allergenicity. However, producing an IgE epitope-specific antibody (IgE-EsAb) through traditional methods requires complex and time-consuming procedures. Here, IgE-EsAb was purified from rabbit anti-BLG sera by immunomagnetic beads in one step. Then, a sandwich ELISA (sELISA) based on the IgE-EsAb was developed to detect BLG and predict the potential milk allergenicity in foods. The obtained IgE-EsAb could specifically recognize the target IgE epitope of BLG and exhibited high affinity and specificity. The developed IgE-EsAb-based sELISA demonstrated an ultra-wide linear range of 3.9-1.28 × 105 ng/mL, with a limit of detection of 0.49 ng/mL for BLG. Additionally, the proposed immunoassay showed high specificity and recoveries (91.24-109.61%). The ability of the IgE-EsAb-based sELISA to evaluate the potential milk allergenicity in foods was validated using sera from cow milk allergy patients. These results suggest that immunomagnetic beads are an effective tool for rapidly obtaining the IgE-EsAb, and our proposed sELISA could be a reliable and user-friendly method for monitoring trace amounts of BLG and predicting the potential milk allergenicity of food samples.

Automatic Pretreatment of Dispersive Liquid Liquid Microextraction Based on Immunomagnetic Beads Coupled with UPLC-FLD for the Determination of Zearalenone in Corn Oils

Sample pretreatment is a vital step in the detection of mycotoxins, and traditional pretreatment methods are time-consuming, labor-intensive and generate much organic waste liquid. In this work, an automatic, high-throughput and environmentally friendly pretreatment method is proposed. Immunomagnetic beads technology and dispersive liquid-liquid microextraction technology are combined, and the zearalenone in corn oils is directly purified and concentrated under the solubilization effects of surfactant. The proposed pretreatment method allows for the batch pretreatment of samples without pre-extraction using organic reagents, and almost no organic waste liquid is produced. Coupled with UPLC-FLD, an effective and accurate quantitative detection method for zearalenone is established. The recovery of spiked zearalenone in corn oils at different concentrations ranges from 85.7 to 89.0%, and the relative standard deviation is below 2.9%. The proposed pretreatment method overcomes the shortcomings of traditional pretreatment methods and has broad application prospects.

Rapid Detection of Staphylococcus aureus in Milk and Pork via Immunomagnetic Separation and Recombinase Polymerase Amplification

Separation processes using immunomagnetic beads (IMBs) are advantageous for the rapid detection of Staphylococcus aureus (S. aureus). Herein, a novel method, based on immunomagnetic separation using IMBs and recombinase polymerase amplification (RPA), was employed to detect S. aureus strains in milk and pork. IMBs were formed by the carbon diimide method using rabbit anti-S. aureus polyclonal antibodies and superparamagnetic carboxyl-Fe3O4 MBs. The average capture efficiency for 2.5 to 2.5 × 105 (CFU)/mL gradient dilution of S. aureus with 6 mg of IMBs within 60 min were a range of 62.74 to 92.75%. The detection sensitivity of the IMBs-RPA method in artificially contaminated samples was 2.5 × 101 CFU/mL. The entire detection process was completed within 2.5 h, including bacteria capture, DNA extraction, amplification, and electrophoresis. Among 20 actual samples, one case of raw milk sample and two cases of pork samples were tested positive using the established IMBs-RPA method, which were verified by the standard S. aureus inspection procedure. Therefore, the novel method shows potential for food safety supervision owing to its short detection time, higher sensitivity, and high specificity. IMPORTANCE Our study established IMBs-RPA method, which simplified the steps of bacteria separation, shortened the detection time, and realized the convenient detection of S. aureus in milk and pork samples. IMBs-RPA method was also suitable for the detection of other pathogens, providing a new method for food safety monitoring and a favorable basis for rapid and early diagnosis of diseases.

Isolation of Fusobacterium nucleatum from human feces using immunomagnetic separation coupled with fastidious anaerobe agar

AIM

Fusobacterium nucleatum (F. nucleatum) is associated with the initiation, development, and metastasis of colorectal cancer. However, it is difficult to isolate F. nucleatum from clinical specimens. In this study, we aimed to develop an effective and rapid method for isolating F. nucleatum from human feces using polyclonal antibody (PAB)-coated immunomagnetic beads (IMBs) with selective media.

METHODS AND RESULTS

IMBs conjugated with PAB were prepared and used to isolate F. nucleatum from human feces, and the bacteria were cultured with selective culture media (fastidious anaerobe agar + nalidixic acid + vancomycin). Under optimized experimental conditions, IMBs could selectively recover F. nucleatum from fecal microbiota samples spiked with Peptostreptococcus or Bacteroides fragilis. In artificial fecal samples, the detection sensitivity of IMBs for F. nucleatum was 103 CFU mL-1. In addition, IMBs combined with selective media could rapidly isolate F. nucleatum from human feces.

CONCLUSIONS

This study successfully established an effective method for the rapid isolation of F. nucleatum from human feces by IMBs. The whole procedure requires 2-3 days, and has a sensitivity of 103 CFU mL-1 feces.

Simple Staining of Cells on a Chip

Simple staining of cells is a widely used method in basic medical diagnostics, education, and research laboratories. The stains are low-cost, but the extensive consumption results in excessive toxic waste generation. Thus, to decrease the amount of toxic waste resulting from the cell staining procedure is a need. In this study, we developed a magnetically driven and compartmentalized passive microfluidic chip to perform simple staining of human eukaryotic cells, K562 cells, and lymphocyte cells derived from patients. We demonstrated simple staining on cells with trypan blue, methylene blue, crystal violet, and safranin for high, medium, and low cell densities. The stained cells were imaged using a bright field optical microscope and a cell phone to count cells on the focal plane. The staining improved the color signal of the cell by 25-135-pixel intensity changes for the microscopic images. The validity of the protocol was determined using Jurkat and MDA-MB-231 cell lines as negative controls. In order to demonstrate the practicality of the system, lymphocyte cells derived from human blood samples were stained with trypan blue. The color intensity changes in the first and last compartments were analyzed to evaluate the performance of the chip. The developed method is ultra-low cost, significantly reduces the waste generated, and can be integrated with mobile imaging devices in terms of portability. By combining microfabrication technology with cell staining, this study reported a novel contribution to the field of microfluidic biosensors. In the future, we expect to demonstrate the detection of pathogens using this method.

pH-Regulated Strategy and Mechanism of Antibody Orientation on Magnetic Beads for Improving Capture Performance of Staphylococcus Species

Immunomagnetic beads (IMBs) have been widely used to capture and isolate target pathogens from complex food samples. The orientation of the antibody immobilized on the surface of magnetic beads (MBs) is closely related to the effective recognition with an antigen. We put forward an available strategy to orient the antibody on the surface of MBs by changing the charged amino group ratio of the reactive amino groups at optimal pH value. Quantum dots labeling antigen assay, antigen-binding fragment (Fab) accessibility assay and lysine mimicking were used for the first time to skillfully illustrate the antibody orientation mechanism. This revealed that the positively charged ε-NH₂ group of lysine on the Fc relative to the uncharged amino terminus on Fab was preferentially adsorbed on the surface of MBs with a negatively charged group at pH 8.0, resulting in antigen binding sites of antibody fully exposed. This study contributes to the understanding of the antibody orientation on the surface of MBs and the potential application of IMBs in the separation and detection of pathogenic bacteria in food samples.

Monovalent Antigen-Induced Aggregation (MAA) Biosensors Using Immunomagnetic Beads in Both Sample Separation and Signal Generation for Label-Free Detection of Enrofloxacin

Exploring new functions of nanomaterials can help facilitate the development of biosensors for the detection of antibiotics. Herein, a new detection modality based on monovalent antigen-induced aggregation (MAA) of immunomagnetic beads (IMBs) was proposed for rapid and label-free detection of enrofloxacin (ENR), which endowed IMBs with the abilities of both sample separation and signal generation. In the presence of ENR, the initially well-dispersed IMBs were aggregated and the degree of aggregation was in a concentration-dependent manner. After exploring the mechanism underlying IMB aggregation and investigating the key parameters affecting it, a label-free biosensing platform was developed for rapid and sensitive detection of ENR. Based on the significant differences in the magnetic separation speed and size between the aggregated and well-dispersed IMBs, two methods were proposed for quantitatively determining ENR, i.e., measuring the turbidity of the IMB supernatant after magnetic separation for a given time and visualizing and calculating the grayscale value of the aggregated IMBs trapped on the surface of a nitrocellulose membrane. A three-dimensional (3D)-printed syringe was designed and fabricated for automatic filtration of IMBs. This immunosensor allowed for sensitive detection of ENR in less than 15 min without any labels. It exhibited a satisfactory limit of detection of 0.79 ng mL^-1 and showed the feasibility for ENR detection of spiked chicken meat with recovery rates ranging from 74.8 to 98.3%. The MAA immunosensor can act as a promising tool to detect trace levels of ENR and has the potential to be applied to complex food samples.

Inertial-Assisted Immunomagnetic Bioplatform towards Efficient Enrichment of Circulating Tumor Cells

Serving as an effective biomarker in liquid biopsy, circulating tumor cells (CTCs) can provide an accessible source for cancer biology study. For the in-depth evaluation of CTCs in cancer analysis, their efficient enrichment is essential, owing to their low abundance in peripheral blood. In this paper, self-assembled immunomagnetic beads were developed to isolate CTCs from the ordered bundles of cells under the assistance of the spiral inertial effect. Parametric numerical simulations were performed to explore the velocity distribution in the cross section. Based on this chip, rare CTCs could be recovered under the throughput of 500 μL/min, making this device a valuable supplement in cancer analysis, diagnostics, and therapeutics.

Preparation of immunomagnetic beads coupled with a rhodamine hydrazine immunosensor for the detection of Mycobacterium avium subspecies paratuberculosis in bovine feces, milk, and colostrum

The aim of this study was to develop and evaluate a method for detecting Mycobacterium avium ssp. paratuberculosis (MAP) bacteria in bovine fecal, milk, and colostrum samples using immunomagnetic beads (IMB) and a rhodamine hydrazone immunosensor. Immunomagnetic beads were prepared by using purified antibodies from hyperimmunized sera that were coupled to Fe nanoparticles with diethylene triamine pentaacetic acid (DTPA) or ethyl (dimethyl aminopropyl) carbodiimide (EDC)-N-hydroxy succinimide (NHS) as linkers. Rhodamine hydrazone particles were synthesized and coupled to IgY anti-MAP antibodies using DTPA or EDC-NHS linkers. Separation efficiency of the IMB was tested on bovine fecal, milk, and colostrum samples experimentally contaminated with MAP. The studied methods were evaluated on their ability to detect MAP and separate bacteria in complex mediums. The ELISA results indicated 95% efficacy in antibody coupling to IMB, with the DTPA-IMB method being more efficient than the EDC-NHS-IMB method. By using the DTPA-IMB method, MAP bacteria were successfully recovered from fecal, milk, and colostrum samples. The DTPA-IMB method used in combination with the rhodamine hydrazone immunosensor had a limit of detection equal to 30 and 30,000 MAP cells/mL using chromogenic and fluorescent properties, respectively. Combining the DTPA-IMB separation method with the rhodamine hydrazone immunosensor provides a fast, sensitive, and cost-beneficial method for detecting MAP in bovine feces, milk, and colostrum.

Combination of Immunomagnetic Separation with Aptamer-Mediated Double Rolling Circle Amplification for Highly Sensitive Circulating Tumor Cell Detection

Breast cancer is the most frequently diagnosed cancer among women, and the circulating tumor cell (CTC)-meditated distant metastasis is the leading cause of death. Thus, the detection of CTCs is of great importance for the early diagnosis of breast cancer and the prevention of metastasis. In this study, using human breast carcinoma BT474 cells as the model CTCs, a powerful assay platform is demonstrated by fluorescence spectrometry for the highly sensitive CTC detection by combining the dual-recognizing elements receptor-binding antibody and aptamer-mediated separation with double rolling circle amplification reactions (d-RCA, including RCA1 and RCA2). The aptamer-inserted RCA1 product (RCA1-p) exhibits the considerably improved affinity towards target cells originating from the multivalent binding effect. The immunomagnetic separation removes nontarget cells coexisting in complex biological milieu, while the centrifugal separation of cells/DNAs mixture eliminates the excess probes, thereby circumventing the unwanted interferences. The fluorescence spectrometric results show that a 34-fold enhanced fluorescence signal is achieved upon BT474 cells, and the target cells can be quantitatively detected down to 9 cells/200 μL with the linear range of five orders of magnitude, indicating a significantly enhanced detection performance. Even if BT474 cells are spiked in the fresh whole blood, no obvious fluctuation in the fluorescence signal is detected, demonstrating that the newly developed d-RCA assay system is suitable for screening CTCs in complex environments and is expected to be a promising tool for estimating distant metastasis and predicting the recurrence of tumors.

Quality Assessment and Comparison of Plasma-Derived Extracellular Vesicles Separated by Three Commercial Kits for Prostate Cancer Diagnosis

Introduction

Current standard biomarkers in clinic are not specific enough for prostate cancer (PCa) diagnosis. Extracellular vesicles (EVs) are nano-scale vesicles released by most mammalian cells. EVs are promising biomarker source for PCa liquid biopsy due to its minimal invasive approach, rich information and improved accuracy compared to the clinical standard prostate-specific antigen (PSA). However, current EV separation methods cannot separate pure EVs and the quality characteristics from these methods remain largely unknown. In this study, we evaluated the quality characteristics of human plasma-derived EVs by comparing three clinical suitable separation kits.

Methods

We combined EV separation by commercial kits with magnetic beads capture and flow cytometry analysis, and compared three kits including ExoQuick Ultra based on precipitation and qEV35 and qEV70 based on size exclusion chromatography (SEC).

Results

Our results indicated that two SEC kits provided higher EV purity and lower protein contamination compared to ExoQuick Ultra precipitation and that qEV35 demonstrated a higher EV yield but lower EV purity compared to qEV70. Particle number correlated very well particularly with CD9/81/63 positive EVs for all three kits, which confirms that particle number can be used as the estimate for EV amount. At last, we found that several EV metrics including total EVs and PSA-specific EVs could not differentiate PCa patients from health controls.

Conclusion

We provided a systematic workflow for the comparison of three separation kits as well as a general analysis process in clinical laboratories for EV-based cancer diagnosis. Better EV-associated cancer biomarkers need to be explored in the future study with a larger cohort.

Rapid determination of aflatoxin B1 by an automated immunomagnetic bead purification sample pretreatment method combined with high-performance liquid chromatography

We aimed to establish an automated versatile sample preconcentration method based on the modified immunomagnetic beads, which was utilized to enrich for aflatoxin B1 from the matrices. The critical main parameters affecting the extraction efficiency, such as usage amount of immunomagnetic beads, reaction time, elution time, and blending way were investigated. Under the optimized conditions, the content of aflatoxin B1 was analyzed by high-performance liquid chromatography, the mobile phase consists of water-acetonitrile-methanol (42:18:10, v/v/v), and fluorescence detection was performed with excitation and emission wavelengths at 360 and 440 nm, respectively. Moreover, the performance of preconcentration method was compared with the conventional method based on the immunoaffinity column. The accuracy of two clean-up methods was within the error range. In addition, the stability and recyclability of the immunomagnetic beads was studied by recycling them five times. The results for the respective analysis in various samples demonstrated that the developed extraction platform provides a promising approach that is simple, rapid, sensitive, and easy to use.

Determination of 3-Methyl-quinoxaline-2-carboxylic Acid and Quinoxaline-2-carboxylic Acid in Pork Based on a Background Fluorescence Quenching Immunochromatographic Assay

A novel rapid method based on a background fluorescence quenching immunochromatographic assay (bFQICA) was established to achieve simultaneously the quantitative detection of 3-methyl-quinoxaline-2-carboxylic acid (MQCA) and quinoxaline-2-carboxylic acid (QCA), which were efficiently extracted and enriched 4 times using immunomagnetic beads from pork. The analysis of field pork samples by bFQICA was in accordance with that of LC-MS/MS; especially, the proposed bFQICA exhibited great advantages in convenience and efficiency, which only takes 30 min for the detection of MQCA and QCA.

Detection of Salmonella Enterica in Egg Yolk by PCR on a Microfluidic Disc Device Using Immunomagnetic Beads

Salmonella enterica is a pathogenic bacterium that causes foodborne illness. One of the vehicle foods of S. enterica are chicken eggs. Efficient collection of the bacterium is necessary to detect it specifically. We developed a method to detect S. enterica by PCR on a microfluidic disc device using a fluorescent probe. Salmonella enterica cells were isolated in the microchambers on the device, followed by thermal lysis and PCR targeting with the invA gene, a gene specific to S. enterica, were observed by measurement of the fluorescent signal that resulted from gene amplification. However, the developed method was unable to discriminate viable cells from dead cells. Consequently, in this study, magnetic beads modified with anti-Salmonella antibody were utilized to detect viable Salmonella cells from egg yolk prior to PCR on the device. While using the antibody-modified beads, egg yolk components, which inhibit PCR, were removed. The collected cells were subsequently detected by PCR of the invA gene on a microfluidic disc device. This method enabled the detection of viable cells without the inhibition of PCR by any egg component. S. enterica was detected at 5.0×10⁴ cells mL⁻¹ or at a higher concentration of egg yolk within 6 h including the sampling time.

[Separation and forensic identification of sperm from cell mixtures using anti-hLCN6 monoclonal antibody coupled magnetic beads]

Human lipocalin 6 (hLCN6) is an epididymis-specific secretory protein. It binds to sperm and plays important role in sperm maturation. To explore the feasibility for isolating spermatozoa from mixed cells using anti-hLCN6 monoclonal antibody-conjugated immunomagnetic beads (anti-hLCN6 IMBs) and establish a new method for the separation of sperms from mixed stains, 2 sets of 30 cases of cell mixture suspensions and stains containing different proportions of sperm and epithelial cells were prepared. Biotin-labeled anti-hLCN6 monoclonal antibody (mAb) was incubated with the cell mixtures, and the spermatozoa were then isolated with avidin-coated IMBs. Sperm DNA was extracted and analyzed by PCR-STR typing. Differential lysis was also conducted to compare the effect of the two different isolation methods. The dissociation constant (Kd) of anti-hLCN6 mAb was 3.47×10⁻⁹ mol/L measured by ELISA. Western blotting and immunofluorescence assays showed that hLCN6 was detectable on sperm cells and mainly located on the post-acrosomal region of the sperm head, but not in epithelial cells. Anti-hLCN6 IMBs could capture and separate the sperm cells successfully. Microscopic observation showed that the IMBs could bind to the head of sperm specifically. The success rate of STR typing (more than 13 STR loci, RFU>200) was 90% when the number of sperm cells was 10³/mL and 100% when the sperm cells number was equal to or more than 10⁴/mL. When the number of sperm cells was 10³/mL, 10⁴/mL and 10⁵/mL in mixed stain samples, the success rate of STR typing were 40%, 90% and 100%, respectively. Taken together, the anti-hLCN6 immunomagnetic beads (IMB) method described here could be effective for the isolation of sperm from mixed cells, and the success rate was higher than that of the traditional differential lysis strategy. IMB sorting is a simple and efficient method for the separation of sperms from sperm and epithelial cell mixture, and can be utilized as a supplementary method for forensic mixture samples analysis in sexual assault cases.

Immunomagnetic enrichment to evaluate the role of home environment specimens in transmission of enterovirus 71

Enterovirus 71 (EV71) immunomagnetic enrichment technique and routine detection methods were combined to detect swab environmental specimens to elucidate the role of environmental specimens in the spread of EV71. Immunomagnetic beads with specific enrichment of EV71 virus were prepared, then the beads were used to absorb the EV71 virus from environmental samples. Obtained immunomagnetic bead-virus complexes were detected by RT-PCR, RT-qPCR and cell culture. Isolated virus were subjected to VP1 full-length amplification and homology analysis was performed. A total of 4 µg of EV71 monoclonal antibody was mixed with 50 µl magnetic beads, and the highest coating efficiency was reached after incubating at room temperature for 2 h. Satisfactory enrichment effect was achieved by adding 50 µl immunomagnetic beads to 1.5 ml sample and shaking at room temperature for 2 h. The method of EV71 enrichment has high sensitivity and specificity. A total of 346 specimens after enrichment by immunomagnetic beads, the positive rates of RT-qPCR, RT-PCR and cell culture were 20.52, 5.78, and 9.25%, respectively, which were also significantly higher than those before enrichment (15.90, 3.47 and 4.05%; P<0.05). After enrichment with immunomagnetic beads, isolation rate of EV71 virus from case specimens and home environment specimens increased from 27.45 to 43.14% and from 0 to 5.29%, respectively. In home environment-positive specimens, positive rate of toys and stationery was high (52.00 and 24.00%, respectively). In kindergarten environmental samples, the positive rate of RT-qPCR was 6.12%, and EV71 virus was not isolated. Sequence analysis showed that the nucleotide homology of case isolates and home environment isolates was 98.0–100%.

Direct Detection of Escherichia coli, Staphylococcus aureus, and Salmonella spp. in Animal-derived Foods Using a Magnetic Bead-based Immunoassay

In this study, an immuno-magnetic bead (IMB)-based assay was developed to simultaneously detect Escherichia coli, Staphylococcus aureus, and Salmonella spp. and was tested in four animal-derived foods: beef, ham, egg, and ricotta cheese. The IMB-based assay exhibited good specificity by binding to five E. coli serotypes [capture efficiency (CE) average (avg.) 90.4%], five S. aureus strains (CE avg. 91.4%), and five Salmonella serotypes (CE avg. 95.4%) but not binding to non-target bacteria (CE<10%). Furthermore, the assay detected all three pathogens with a detection limit of 10 CFU/g without the need for enrichment or additional platforms. Since the results demonstrated that the IMB-based assay can effectively separate and enrich target bacteria from a variety of animal-derived food matrixes, the assay exhibits good specificity for potential use in providing rapid, immunological, presumptive identification of pathogenic bacteria.

[Polyclonal antibody and immunomagnetic beads preparation technology for type A trichothecenes]

OBJECTIVE

Preparing immunomagnetic beads for enrichment and purification of mask type A trichothecenes.

METHODS

Through immunizing New Zealand white rabbits with family A toxin artificial antigen 3-Ac-NEOS-HS-BSA, the polyclonal antibodies of type A trichothecenes( type A family) were isolated, as well as its antibody titre were determinated and purified. The coupling condition of high titer antibody and immunomagnetic beads were optimized and applied.

RESULTS

After 5 times of immunization with type A trichothecene family toxin, the rabbit serum inhibited the highest antibody titer( 1 : 64 000). The optimal coupling condition of antibody and immunomagnetic beads were: temperature = 24 ℃, rotation capture in pH 7. 4, 0. 02 mol/L PBS buffer solution with 10% methanol in 24 h.

CONCLUSION

The establishment of preparation method of type A single family toxin polyclonal antibody and immunomagnetic beads can make a standard for enrichment and purification of type A matrix complex single family toxins.

Detection of circulating tumour cells in patients with epithelial ovarian cancer by a microfluidic system

Ovarian cancer is a gynaecological cancer with a high mortality rate. In recent years, circulating tumour cells (CTCs) have attracted attention from scientists because of their significant association with metastasis. However, due to the low CTC enrichment rate of the conventional CellSearch system and limited clinical sample sizes, only a small number of studies have focused on CTCs and epithelial ovarian cancer (EOC). Here, we apply a microfluidic system with immunomagnetic beads preconjugated with an anti-EpCAM antibody to enrich CTCs from whole blood and then analyse the enriched cells by immunofluorescence staining and automatic fluorescence microscope scanning. The average recovery rate of SK-OV-3 EOC cells was 70.2%±13.3%. When using blood samples from EOC patients and healthy volunteers, CTC counts of more than 8 cells were detected in 20 of 23 EOC patients (87.0%) but in none of the 16 healthy volunteers (0%). Total CTC counts were found to be significantly (P<0.05) elevated in the EOC group (median =55.0 [29.5, 123.0] CTCs/7.5 mL) compared with the healthy control group (median =0.5 [0,3.5] CTCs/7.5 mL). In conclusion, this is the first study to use the IsoFlux system on ovarian cancer samples. This system can efficiently capture EOC CTCs from a majority of patients and may provide a potential tool for further biological studies and for the development of in vitro EOC diagnostic products.

Isolation, cultivation and identification of brain glioma stem cells by magnetic bead sorting

This study describes a detailed process for obtaining brain glioma stem cells from freshly dissected human brain glioma samples using an immunomagnetic bead technique combined with serum-free media pressure screening. Furthermore, the proliferation, differentiation and self-renewal biological features of brain glioma stem cells were identified. Results showed that a small number of CD133 positive tumor cells isolated from brain glioma samples survived as a cell suspension in serum-free media and proliferated. Subcultured CD133 positive cells maintained a potent self-renewal and proliferative ability, and expressed the stem cell-specific markers CD133 and nestin. After incubation with fetal bovine serum, the number of glial fibrillary acidic protein and microtubule associated protein 2 positive cells increased significantly, indicating that the cultured brain glioma stem cells can differentiate into astrocytes and neurons. Western blot analysis showed that tumor suppressor phosphatase and tensin homolog was highly expressed in tumor spheres compared with the differentiated tumor cells. These experimental findings indicate that the immunomagnetic beads technique is a useful method to obtain brain glioma stem cells from human brain tumors.

Clinical test on circulating tumor cells in peripheral blood of lung cancer patients, based on novel immunomagnetic beads

This paper aims to establish a novel and highly sensitive method to detect circulating tumor cells (CTCs) in the peripheral blood of patients with lung cancer. This therefore enables the discovery of invisible micrometastasis in the early stage of lung cancer, leading to better prognostic assessments of lung cancer and detection of the post-operative tumor recurrence and metastasis, treatment options, and evaluation of curative effects. In this research study, various lung cancer cells were mixed with adult blood samples to simulate blood samples of tumor patients. With novel test methods, CTCs in peripheral blood of lung cancer patients were calculated, after the reaction between the cells obtained from the mix and EpCAM (epithelial cell adhesion molecule) antibodies which were marked by immunomagnetic beads. The results showed that 18 out of 42 (42.9%) lung cancer patients had a positive CTCs, which increased with tumor enlargement or metastasis. CTCs were not detected in a total of 20 blood samples from healthy volunteers. This indicated that the technology of novel immunomagnetic bead-enrichment could effectively separate and identify CTCs in peripheral blood of lung cancer patients, which is of great clinical value for prognostic assessments and treatment guidance of lung cancer.

TNF as biomarker for rapid quantification of active Staphylococcus enterotoxin A in food

Staphylococcus aureus is a major bacterial pathogen which causes clinical infections and food poisoning. This bacterium produces a group of twenty-one enterotoxins (SEs). These enterotoxins have two separate but related biological activities. They cause gastroenteritis and function as superantigens that activate large numbers of T cells. The current method for detection of enterotoxins activity is an in vivo monkey or kitten bioassay; however, this method is not practical to test on a large number of samples. Several immunological assays have been developed however, but these assays cannot distinguish between active toxin which causes food poisoning and inactive toxin, which can bind antibody, but shows no toxicity. The current study demonstrates that short term ex vivo exposure of primary naïve CD4(+) T-cells or splenocytes to SEA induces differential expression and secretion of tumor necrosis factor (TNF) protein. We used immunomagnetic beads coated with anti-SEA antibody to specifically isolate SEA from food. After the eluted toxin was added to the cells SEA biological activity was measured by quantifying TNF protein expression or secretion.

Identification and characterization of biomarkers of organophosphorus exposures in humans

Over 1 billion pounds of organophosphorus (OP) chemicals are manufactured worldwide each year, including 70 million pounds of pesticides sprayed in the US. Current methods to monitor environmental and occupational exposures to OPs such as chlorpyrifos (CPS) have limitations, including low specificity and sensitivity, and short time windows for detection. Biomarkers for the OP tricresyl phosphate (TCP), which can contaminate bleed air from jet engines and cause an occupational exposure of commercial airline pilots, crewmembers and passengers, have not been identified. The aim of our work has been to identify, purify, and characterize new biomarkers of OP exposure. Butyrylcholinesterase (BChE) inhibition has been a standard for monitoring OP exposure. By identifying and characterizing molecular biomarkers with longer half-lives, we should be able to clinically detect TCP and OP insecticide exposure after longer durations of time than are currently possible. Acylpeptide hydrolase (APH) is a red blood cell (RBC) cytosolic serine proteinase that removes N-acetylated amino acids from peptides and cleaves oxidized proteins. Due to its properties, it is an excellent candidate for a biomarker of exposure. We have been able to purify APH and detect inhibition by both CPS and metabolites of TCP. The 120-day lifetime of the RBC offers a much longer window for detecting exposure. The OP-modified serine conjugate in the active site tryptic peptide has been characterized by mass spectrometry. This research uses functional proteomics and enzyme activities to identify and characterize useful biomarkers of neurotoxic environmental and occupational OP exposures.

Capture of Escherichia coli O157:H7 Using Immunomagnetic Beads of Different Size and Antibody Conjugating Chemistry

Immunomagnetic beads (IMB) were synthesized using anti-Escherichia coli O157 antibodies and magnetic beads of two different sizes (1 μm and 2.6 to 2.8 μm) that contained a streptavidin coating, activated carboxyl groups or tosylated surfaces. The synthesized IMB, together with a commercially available IMB, were used to capture different strains of E. coli O157:H7 and E. coli O157:NM. The E. coli capture was measured by the time resolved fluorescence (TRF) intensity using a sandwich assay which we have previously demonstrated of having a sensitivity of 1 CFU/g after 4.5 hour enrichment [1]. The analyses of measured TRF intensity and determined antibody surface concentration indicated that larger beads provided higher response signals than smaller beads and were more effective in capturing the target of interest in pure culture and ground beef. In addition, while each type of IMB showed different favorable capture of E. coli O157:H7, streptavidin-coated IMB elicited the highest response, on average. Streptavidin-coated IMB also provided an economic benefit, costing less than $0.50 per assay. The results could be used to guide the proper choice of IMB for applications in developing detection processes for E. coli O157:H7.

Detection of telomerase activity in peritoneal lavage fluid from patients with gastric cancer using immunomagnetic beads

Cytologic examination of peritoneal lavage fluid is a useful predictor of peritoneal recurrence in gastric cancer. However, this technique is not overly sensitive and requires special abilities in the cytologist. In this study, telomerase activity was used to detect free cancer cells in peritoneal lavage fluid from patients with gastric cancer. In the first part, 12 lavage-fluid samples obtained from 12 patients with gastric cancer were analysed using the conventional telomeric repeat amplification protocol (TRAP) assay. Three of five patients with early gastric cancer had positive telomerase activity. These false-positive results may have been due to lymphocyte contamination. Furthermore, polymerase chain reaction inhibitors were also detected in the lavage-fluid samples. Therefore, we developed a novel method for elimination of haematopoietic cell and Taq polymerase inhibitors to increase the accuracy of the TRAP assay using immunomagnetic beads, which bind to most normal and neoplastic human epithelial cells. Telomerase activity was found in 10 of 20 (50%) lavage-fluid samples from patients with serosal or subserosal invasion. Cytologic examination was positive in nine of 20 (45%) samples. Both the telomerase activity and cytology were negative in all 14 patients without serosal or subserosal invasion. These results suggest that the TRAP assay combined with immunomagnetic beads might be useful for detection of free cancer cells in the peritoneal space in gastric cancer without the aid of an experienced cytologist.

Application of immunomagnetic beads in combination with RT-PCR for the detection of circulating prostate cancer cells

Recently published protocols using Reverse Transcriptase Polymerase Chain reaction (RT-PCR) for prostate specific antigen (PSA) provide a sensitive means for detecting circulating prostate cancer cells. Attempts to use these assays for staging of prostate cancer have produced conflicting results. As a first step towards rectifying these discrepancies, a modified immunobead-RT-PCR assay capable of detecting as few as 10 prostate cancer cells in 8cc of blood was developed. This 10 fold increase in sensitivity was achieved in part by introducing two target cell enrichment steps. As a model system to assess sensitivity of the modified assay, template RNA was extracted from PSA positive human carcinoma cells suspended in human blood and isolated with immunomagnetic beads following incubation with an epithelium specific antibody. After 45 cycles of PCR, product from as few as 10 target cells could be readily detected when displayed on a 2% agarose gel stained with SYBR Green fluorescent dye. The identity of amplified DNA fragments was confirmed by Southern blot hybridization. When applied to blood samples from patients with proven metastatic disease, the immuno-bead RT-PCR assay was successful in detecting circulating PSA positive epithelial cells, suggesting this assay may be useful for assessment of disease progression or recurrence.