Magnetic Separation Technology Research Articles

Calcined MgFe layered double hydroxides for magnetic separation and enhanced adsorption performance of methyl orange: Mechanism based on the memory effect

This study successfully synthesized magnetic MgFe-layered double oxides (MgFe-LDO-500 °C) by calcining MgFe-layered double hydroxides (MgFe-LDHs) at 500 °C. Calcination temperature was identified as a critical factor for optimizing adsorption capacity and activating a memory effect, with 500 °C being particularly effective. The adsorption performance of MgFe-LDO-500 °C towards methyl orange (MO) in aqueous solutions was evaluated across varying pH levels (2–12), initial MO concentrations (50–1800 mg/L), contact times (0–1440 min), and temperatures (25–45 °C). The results indicated that MgFe-LDO-500 °C adsorption conforms to the pseudo-second-order kinetic and Langmuir models, achieving a theoretical maximum adsorption capacity of 5087.76 mg/g. Characterization through scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Zeta potential analysis revealed that the outstanding adsorption performance of MgFe-LDO-500 °C towards MO involves a combination of electrostatic attraction, memory effect, and surface complexation. Moreover, after four regeneration cycles, the material maintained a 73 % MO removal efficiency and could be efficiently separated using magnetic separation technology. In conclusion, MgFe-LDO-500 °C represents a promising adsorbent for wastewater treatment.

Fabrication of magnetic hydrophilic imprinted polymers via two-step immobilization approach for targeted detecting bisphenol A

Molecularly imprinted polymer with water-compatibility for effective separation and enrichment of targeted trace pollutants from complicated matrix has captured extensive attention in terms of their high selectivity and matrix compatibility. This study focuses on modified β-cyclodextrin is used as a hydrophilic functional monomer to develop magnetic molecularly imprinted polymers (MMIPs). MMIPs were prepared using Fe3O4 nanoparticles as carriers and bisphenol A (BPA) as templates using a two-step fixation strategy and surface imprinting technology. The structural characteristic and binding properties of the prepared MMIPs were thoroughly studied. The MMIPs exhibited high crystallinity, high adsorption capacity, fast rebinding rate, remarkable selectivity and distinguish reusability. In addition, through magnetic solid-phase extraction separation technology and high-performance liquid chromatography ultraviolet quantitative detection technology, MMIPs are used for selective enrichment and detection of BPA in complex media such as environmental water and milk. This work provides a new route to construct the hydrophilic molecularly imprinted materials and a new sight on developing more effective sample pretreatment strategies for monitoring targeted pollution in complicated aqueous media.

Development of aptamer surface-enhanced Raman spectroscopy sensor based on Fe3O4@Pt and Au@Ag nanoparticles for the determination of acetamiprid.

As a common chlorinated nicotinic pesticide with high insecticidal activity, acetamiprid has been widely used for pest control. However, the irrational use of acetamiprid will pollute the environment and thus affect human health. Therefore, it is crucial to develop a simple, highly sensitive, and rapid method for acetamiprid residue detection. In this study, the capture probe (Fe3O4@Pt-Aptamer) was connected with the signal probe (Au@DTNB@Ag CS-cDNA) to form an assembly with multiple SERS-enhanced effects. Combined with magnetic separation technology, a SERS sensor with high sensitivity and stability was constructed to detect acetamiprid residue. Based on the optimal conditions, the SERS intensity measured at 1333cm-1 is in relation to the concentration of acetamiprid in the range 2.25 × 10-9-2.25 × 10-5M, and the calculated limit of detection (LOD) was 2.87 × 10-10M. There was no cross-reactivity with thiacloprid, clothianidin, nitenpyram, imidacloprid, and chlorpyrifos, indicating that this method has good sensitivity and specificity. Finally, the method was applied to the detection of acetamiprid in cucumber samples, and the average recoveries were 94.19-103.58%, with RSD < 2.32%. The sensor can be used to analysereal samples with fast detection speed, high sensitivity, and high selectivity.

Application of Magnetic Separation Technology in Resource Utilization and Environmental Treatment

Magnetic separation technology is a physical separation method that uses the differences in magnetism between matter to separate them from each other by different motion behaviors in a non-uniform magnetic field. It is highly efficient, green, and environmentally friendly, with little change in the physical and chemical properties of raw materials. Magnetic separation technology is commonly used in the field of mineral processing engineering for magnetite, hematite, titanite, and other magnetic ferrous metal oxide minerals. This paper summarizes the application of magnetic separation technology for resource utilization and environmental treatment in different fields, such as non-metal decomposition, valuable metal recovery, use of magnetic carrier chemical separation, biomedical targeted magnetic separation, and use of magnetic species separation in water and wastewater treatment. We seek to review the application and potential of magnetic separation technology in various fields, emphasize their key role, and explore possible directions for their future development.

Point-of-care testing of methamphetamine and cocaine utilizing wearable sensors

The imperative for the point-of-care testing of methamphetamine and cocaine in drug abuse prevention necessitates innovative solutions. To address this need, we have introduced a multi-channel wearable sensor harnessing CRISPR/Cas12a system. A CRISPR/Cas12a based system, integrated with aptamers specific to methamphetamine and cocaine, has been engineered. These aptamers function as signal-mediated intermediaries, converting methamphetamine and cocaine into nucleic acid signals, subsequently generating single-stranded DNA to activate the Cas12 protein. Additionally, we have integrated a microfluidic system and magnetic separation technology into the CRISPR system, enabling rapid and precise detection of cocaine and methamphetamine. The proposed sensing platform demonstrated exceptional sensitivity, achieving a detection limit as low as 0.1 ng/mL. This sensor is expected to be used for on-site drug detection in the future.

A fluorescence-electrochemical dual-mode aptasensor based on novel DNA-dependent PBNFs@PtPd for highly selective and sensitive detection of procymidone through hybridization chain reaction

Herein, a study for the first application of a hybridization chain reaction, a 1,8-naphthalimides-DNA (NDs) intercalator, and DNA-dependent Prussian blue nanoflowers@PtPd materials (PBNFs@PtPd) in the development of a fluorescence-electrochemical (FL-EC) aptasensor. This construction establishes an efficient sensing platform for the detection of procymidone (PCM). In the context of the described experiment, dual-mode detection is achieved through the generation of FL signals by an aptamer labeled with a Cy5 moiety and the formation of DPV signals by the modification of a thionine-appended 1,8-naphthalimide (Thi-NDs). In the presence of PCM, specific recognition occurs, followed by the utilization of magnetic separation technology to release DNA1 (S1) and aptamer-Cy5 (Apt-Cy5), subsequently introducing them onto both fluorescence and EC platforms. The presence of S1 effectively activates hybridization chain reaction (HCR) for the electrode surface, thereby significantly increasing the binding sites for Thi-NDs and consequently greatly amplifying the response signal of differential pulse voltammetry (DPV). The developed FL-EC dual-mode sensing platform demonstrates high sensitivity in the detection of PCM, with the detection limits of 0.173 μg·ml−1 (within the detection range of 500 pg·ml−1 to 500 ng·ml−1) and 0.074 ng·ml−1 (within the detection range of 100 pg·ml−1 to 100 ng·ml−1), respectively. The designed dual-mode sensor exhibits notable characteristics, including high selectivity, reproducibility, synergy, and reliable monitoring/capability for PCM in real samples.

Abstract 6331: A novel automated platform for rapid manufacturing of CAR T cells

Abstract Autologous cell therapy using genetically modified T cells to express chimeric antigen receptor (CAR) has yielded durable responses in cancers patients. However, currently only a small portion of patients are privileged to receive the treatment. High cost and long manufacturing time contribute to the key limitations prohibiting cell therapy broad adoption. Researchers discovered that reducing ex vivo culture improves anti-tumor activity of CAR T cells1 and recently demonstrated the process of generating functional CAR T cells within 24 hours2. This rapid process provides great promise in cost reduction of CAR T therapy and opportunity to have cells manufactured in close-to-patient settings. CART cell manufacturing process involves: (1) collection of peripheral blood; (2) isolation of T cells; (3) performing transduction via viral vector; (4) washing CAR T cells to remove viral vector, and (5) harvesting CAR T cells in IV fluid. Conventional process uses magnetic separation and serial centrifugation technologies on multiple platforms with manual operations. Here we demonstrate the feasibility of rapid manufacturing CAR T cells on an automated platform with closed fluidics without centrifugation steps. The platform, MARS® Atlas, is built with innovative technologies in immune-magnetic cell isolation and acoustic cell washing and implemented as a modular system. In this feasibility test, T cells were isolated from peripheral blood from a healthy donoron MARS® magnetic module. eGFP expressing lentivirus were added to the enriched T cells. After short incubation, cells and virus were washed with fresh medium on the MARS® acoustic module and cells were incubated with virus overnight without activation. Infected cells were washed on the acoustic module to remove free virus. Product CAR T cells were harvested in saline solution and ready for QC analysis. Starting from 20mL of peripheral blood, magnetic T cell separation was done 2mL/min achieving 90% T cell purity, 90% recovery. In the first acoustic wash, medium exchange of the mixture of cells and virus took place at 0.9mL/min flow rate. As a result, 90% removal of contaminating molecule and 99.6% recovery of T cells were achieved. The second acoustic wash completed medium exchange of transfected cells at 0.9mL/min with 96.7% removal of virus and 90% CAR T cell recovery. As a result, 18 million GFP expressing T cells were produced. In this study we have demonstrated the feasibility of rapidly manufacturing CAR-T cells on an automated platform MARS® Atlas. This result indicates the MARS® Atlas being a potential CAR T manufacturing platform to be used in close-to-patient settings to enable low-cost cell therapy. 1 Saba Ghassemi, Reducing Ex Vivo Culture Improves the Antileukemic Activity of Chimeric Antigen Receptor (CAR) T Cells, Cancer Immunol Res; 6(9) September 2018 2 Saba Ghassemi, Rapid manufacturing of non-activated potent CAR T cells, Nature Biomedical Engineering | VOL 6 | February 2022 | 118-128 Citation Format: Silin Sa, Ethan Nguyen, Jie Pan, Liping Yu. A novel automated platform for rapid manufacturing of CAR T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6331.

Magnetic Molecularly Imprinted Polymers for Selective Extraction of Aflatoxins from Feeds.

Magnetic molecularly imprinted polymers (MMIPs) have fused molecular imprinting technology with magnetic separation technology, emerging as an innovative material capable of recognizing specific molecules and efficiently separating target substances. Their application to the extraction and purification of mycotoxins has great potential, due to the toxicity and economic impact of these contaminants. In this work, MMIP has been proposed as a sample treatment for the determination of main four aflatoxins (B1, B2, G1 and G2) in pig feed. The MMIP was formed through the integration of magnetic material (Fe3O4) with commercial molecularly imprinted polymers, avoiding the synthesis step and, therefore, simplifying the process. The analyses were carried out by high-performance liquid chromatography with fluorescence detection and the method was validated and limits of quantification (LOQs) between 0.09 and 0.47 ng/g were obtained, below the allowed or recommended levels by the European Union. Repeatability and intermediate precision showed relative standard deviations lower than 10% in all cases and trueness ranged from 92 to 111%. Finally, the proposed method was applied to 31 real pig feed samples, detecting aflatoxins with concentrations between 0.2 and 3.2 ng/g.

A study on the atomic number dependent magnetic properties of lanthanide and actinide oxides for magnetic separation technology

A systematic understanding of atomic number dependent magnetic properties of rare earth oxides is crucial for magnetic separation technology on hazardous industry wastes. In this work, the atomic number dependent magnetic properties of lanthanide and actinide ions were studied. Experimental results of some lanthanide oxides show that the magnetic properties of lanthanide ions are both atomic number dependent and temperature dependent. However, a typical double peak shape of the atomic number dependent magnetic moments is observed at both low and high temperatures. The experimental results of lanthanide oxides agree very well with the theoretical results from molecular magnetic model. Therefore, this molecular magnetic model was further used to predict the magnetic properties of more lanthanide ions and radioactive actinide ions which are not easily accessed experimentally. The theoretically predicted results on actinide ions also show a typical double peak shape of the atomic number dependent magnetic moments due to the similar electron configuration of lanthanide and actinide ions. This work verified the reliability of molecular magnetic model in predicting magnetic properties of lanthanide and actinide ions and provides systematical magnetic data for future magnetic separation technology on those hazardous industry wastes.

Quantitative real-time PCR and magnetic separation strategy for specific detection of group B streptococcus in perinatal Women's urine

IntroductionGroup B streptococcus(GBS)often causes adverse outcomes such as urinary system infection, intrauterine infection, premature birth, and stillbirth in perinatal women. Perinatal screening of GBS is conducive to guiding clinical scientific intervention and improving delivery outcomes.This study quantitative real-time PCR (RT-qPCR) combined with magnetic separation was used for GBS detection. Materials and methodsSample pre-treatment in this study involved the utilization of magnetic separation (MS) technology, aiming to expedite the detection process and enhance detection sensitivity, and the cfb gene of group B streptococcus was used as the target gene to establish quantitative real-time PCR (RT-qPCR) to detect group B streptococcus. ResultsIt was found that penicillin-functionalized magnetic beads had a good ability to enrich and capture group B Streptococcus.The findings revealed an exceptional detection sensitivity, with the ability to detect B streptococcus in urine samples at levels as low as 102 CFU/mL. ConclusionsThe utilization of MS technology in conjunction with the RT-qPCR (MS-RT-qPCR) assay, as demonstrated in this study, offers a viable approach for prenatal screening of group B streptococcus among perinatal women.

Microplastic removal from water using modified maifanite with rotating magnetic field affected

Magnetic separation of microplastics from water is a new generation technology that is cost effective and environmentally friendly, and can avoid secondary pollution. The influence of magnetic Maifanite on polystyrene removal from water was investigated under a magnetic field action time, solution pH, magnetic carrier dosage, and polystyrene concentration, using a developed rotating magnetic field generator. Additionally, the polystyrene removal mechanism by the rotating magnetic field was revealed based on characterization and process simulation. The results showed that Maifanite can increase the number of surface adsorption sites and improve the adsorption performance after high temperature and acid impregnated modification. Specifically, the surface morphology of the modified Maifanite exhibited skirted stripes and a multilayered pore structure. And the specific surface area increased from 3.26 to 20.83 m2/g. The removal process is based on chemical adsorption, supplemented by physical adsorption. The magnetic carrier is tightly wrapped around the polystyrene surface by π bonds between the metal and hydroxy groups, ensuring agglomeration strength. Additionally, the rotating magnetic field generator designed can provide a rotating dynamic magnetic field, and the magnetic particles in the mixed system present a multi-directional helical motion trajectory, thus the walking displacement increases and the capture time decreases. And the probability of collision with non-magnetic particles and the formation of magnetic agglomerates are greatly increased. Thus the adsorption and removal of microplastics are enhanced theoretically. The polystyrene removal efficiency from water using modified Maifanite by rotating magnetic field affected increased by 19.49 %, reaching 98.46 %, and stabilizing at 86.53 % over 25 operation cycles. This study holds promise for advancing magnetic separation technology for microplastics from water.

Preparation of high-purity SiO2 by S-HGMS coupled with mixed-acid leaching: A case study on hematite tailings from Ansteel, China

Hematite tailings (HTs) are rich in silica and are used as replacements for fine aggregates in the preparation of construction materials. However, there is scope for a more effective utilization of the valuable elements present in HTs. In this paper, a process for preparing high-purity SiO2 using HTs procured from Ansteel (China) is proposed. HTs were treated using the superconducting high-gradient magnetic separation (S-HGMS) technology, where the silica as part of the nonmagnetic fraction was obtained in the form of a high-silica concentrate, which was then subjected to mixed-acid leaching to dissolve impurities to achieve refined purification. The optimum process conditions for S-HGMS were determined, and the response surface methodology was applied to optimize the process parameters of the mixed-acid leaching process. The process indicators of the mixed-acid leaching step included the leaching time, leaching temperature, and molar ratio of the mixed acids. The optimum process conditions for S-HGMS were as follows: the magnetic strength-to-velocity ratio in the weak magnetic separation stage was set to 0.034 T·s/m whereas it was maintained at 0.076 T·s/m in the strong magnetic separation stage; the pulp concentration was 40 g/L, the pulp velocity was 500 mL/min, and the dispersant concentration was 1 mg/g. Under these conditions, the high-silica pulp was processed. The corresponding SiO2 grade increased from 71.788 % to 95.260 %, and its recovery and yield reached 56.330 % and 42.450 %, respectively. The SiO2 content in the sample increased from 95.260 % to 99.961 %. Further, the mechanisms of the S-HGMS and mixed-acid leaching were revealed. The proposed process is environmentally friendly and operationally inexpensive. It can reduce the amount of HTs by 42.450 %, and the obtained high-purity silica product has high economic value and good industrialization prospects.

Combined detection of SARS-CoV-2 neutralizing antibodies and specific IgG in plasma based on SERS magnetic sensor

In this study, a surface-enhanced Raman spectroscopy (SERS) magnetic sensor is established based on SERS principle and magnetic separation technology, and a highly sensitive, simple and fast method for quantitative detection of neutralizing antibodies (nABs) and specific IgG of SARS-CoV-2 in plasma is established combined with immunoassay. Two kinds of Raman nanospheres (RNPs) with different characteristic Raman shifts are used as signal sources and coupled to ACE2 and anti-IgG (FC) antibodies respectively, and magnetic beads are coupled to RBD. The competitive relationship between ACE2 and nABs, the binding relationship between specific IgG and anti-IgG (FC) antibodies are determined. The results show that the concentrations of nABs and specific IgG in the range of 10–2000 ng ml−1 are well correlated with SERS response intensity, and the recoveries are both between 90%–110%, with good precision. Bilirubin and common anticoagulants have no interference on the detection results. This method is accurate, reliable, sensitive and does not require complex pre-treatment, and is expected to be used for simultaneous detection of nABs and specific IgG in plasma of SARS-CoV-2. It has guiding significance for the development and evaluation of vaccines and the formulation of individualized vaccination schedule.

An Evaluation of Cesium Removal from Simulated Radioactive Contaminated Soil with a Magnetized Zeolite Derived from Anthracite

The magnetized zeolite with an optimized conversion rate of 53% can be readily synthesized from industrial anthracite using a water-based method. The highly porous structure of ferromagnetism zeolite demonstrates robust magnetic properties with a magnetite content of 12–15%, satisfying adsorbent separation and recycling through magnetic cylinder rotating and vibrating separation. A cesium adsorption and removal efficiency as high as 99.92% with a corresponding adsorbent recovery ratio of up to 96.36% can be achieved for the simulated cesium-contaminated soil with a water content of 20% and a cesium content of 1% with an adsorbent-to-contaminated soil ratio of 1:2. Adsorption and magnetic separation technology with magnetized zeolite synthesized from anthracite exhibited a high cesium removal rate and zeolite recovery ratio, demonstrating promising application potential in treating radioactive waste soils and robust and economically viable engineering feasibility.

A magnetic solid phase chemiluminescent immunoassay for quantification of Cystatin C in human serum

A chemiluminescent immunoassay for human serum Cystatin C (Cys C) was established using a direct-antibody sandwich model. The immunoassay kit uses magnetic separation technology, using magnetic particles as the reaction solid phase, alkaline phosphatase as the marker enzyme, and a new chemiluminescent substrate APLS as the substrate. It has the characteristics of high sensitivity and short reaction time. This product uses high-affinity antibodies, resulting in a high specificity. The established method showed good accuracy, uniformity, and stability. The limit of detection was 2.39 ng/mL. The intra-assay coefficient of variation (CV) was 3.36%–6.00%, the interassay CV was 4.12%–5.35%, and the recovery rate was 99.07%. The correlation coefficient (r) of Cys-C kit was 0.999388 ≥ 0.9900. The accuracy of the developed method was tested by automatic chemiluminescence instrument (P > 0.05). The lowest titer was 0.92500, and the highest was 1.10000. The developed method showed a good correlation with the product from Roche by comparing these two kits in 240 clinical samples from China. In total, 1392 clinical patient from China samples were measured using the reagent kit developed in this study.

Dual-mode detection of KRAS gene by target recycling amplification based on molybdenum disulfide quantum dots and the catalytic reduction of rhodamine B

In this work, a novel dual-mode ratiometric fluorometric and colorimetric system was proposed based on molybdenum disulfide quantum dots (MoS2 QDs) and rhodamine B (RhB) by combining the Exo III-assisted target recycling approach with the magnetic separation method. KRAS (Kirsten rat sarcoma viral oncogene homolog) gene as the target DNA could hybridize with the hairpin DNA to generate the output DNA through exonuclease III-assisted recycling amplification. The output DNA served as a bridge to link magnetic beads labeled with ssDNA1 (MBs-ssDNA1) to gold nanoparticles modified with ssDNA2 (AuNPs-ssDNA2). After magnetic separation, the remaining AuNPs could catalyze the reduction of RhB with the aid of sodium borohydride (NaBH4). When the KRAS gene concentration increased, the AuNPs in the solution decreased and thus less RhB was reduced. In this process, the fluorescence of RhB at 582 nm enhanced while the fluorescence of MoS2 QDs at 420 nm as a reference signal kept unchanged. Meanwhile, the absorbance of the MoS2 QDs/RhB sensing platform at 554 nm gradually increased. The dual-mode fluorometric and colorimetric sensing methods displayed excellent selectivity for KRAS gene determination with limits of detection (LOD) of 0.22 and 0.41 pM, respectively. By combining signal amplification and magnetic separation technology, this method effectively eliminated background interference and improved the sensitivity of the results. The two detection modes were successfully applied to detect the KRAS gene in real samples.

Core-Shell-Shell Upconversion Nanomaterials Applying for Simultaneous Immunofluorescent Detection of Fenpropathrin and Procymidone.

This study synthesized the NaGdF4@NaGdF4: Yb, Tm@NaGdF4: Yb, Nd upconversion nanoparticles (UCNPs), combined with another three-layer structure NaYF4@NaYF4: Yb, Er@NaYF4 UCNPs, with a core-shell-shell structure, effectively suppressing fluorescence quenching and significantly improving upconversion luminescence efficiency. Two types of modified UCNPs were coupled with antibodies against fenpropathrin and procymidone to form signal probes, and magnetic nanoparticles were coupled with antigens of fenpropathrin and procymidone to form capture probes. A rapid and sensitive fluorescence immunoassay for the simultaneous detection of fenpropathrin and procymidone was established based on the principle of specific binding of antigen and antibody and magnetic separation technology. Under the optimal competitive reaction conditions, different concentrations of fenpropathrin and procymidone standards were added to collect the capture probe-signal probe complex. The fluorescence values at 542 nm and 802 nm were measured using 980 nm excitation luminescence. The results showed that the detection limits of fenpropathrin and procymidone were 0.114 µg/kg and 0.082 µg/kg, respectively, with sensitivities of 8.15 µg/kg and 7.98 µg/kg, and they were applied to the detection of fenpropathrin and procymidone in tomatoes, cucumbers, and cabbage. The average recovery rates were 86.5~100.2% and 85.61~102.43%, respectively, with coefficients of variation less than 10%. The results showed good consistency with the detection results of high-performance liquid chromatography, proving that this method has good accuracy and is suitable for the rapid detection of fenpropathrin and procymidone in food.

Separation and preparation of level I standard lead concentrate from lead ore via S-HGMS technology: description of separation mechanism

ABSTRACT To eliminate the adverse effects of traditional lead ore flotation methods, such as high reagent cost, complex operation process, and a large amount of wastewater, a superconducting high gradient magnetic separation (S-HGMS) technology was proposed to prepare level I standard lead concentrate (IGC) from lead ore. Under optimal conditions including a magnetic flow ratio of 0.076 T·s/m, a pulp concentration of 1.5%, a slurry flow velocity of 500 mL/min, and a 90% mass fraction of minus 45 μm, the Pb grade of the IGC product increased from 45.36% to 68.79% with 55.43% of Pb recovery, while all Cu, Zn, As, Fe, MgO, and Al2O3 concentrations of IGC decreased. The obtained IGC product meets the standard of level I in YS/T319–2013. The characterization results showed that lead ore comprised galena, sphalerite, and chalcopyrite. After S-HGMS, galena was effectively concentrated in the IGC product, while sphalerite and chalcopyrite were separated into the tailings. The magnetic field intensity and mineral magnetization characteristics were vital factors affecting the Pb grade and recovery of the IGC product. The S-HGMS technology efficiently achieved the preparation of the IGC product from lead ore, without using flotation agents and generating wastewater, and provides a valuable guideline for separating Cu – Pb, Zn – Pb, and Cu – Zn – Pb minerals.

Fluorometric detection of alpha-fetoprotein based on the use of a novel organic compound with AIE activity and aptamer-modified magnetic microparticles

BackgroundLiver cancer is one of the most common cancers in the world, and it seriously threatens human life and health. Alpha-fetoprotein (AFP), as a carcinogenic glycoprotein, is an important serum marker for detecting liver cancer. Therefore, the accurate and sensitive determination of AFP is crucial for the early diagnosis and treatment of liver cancer. To this end, a label-free fluorescence aptasensor for detecting AFP based on the use of a novel organic Compound D with an aggregation-induced emission activity and aptamer-modified magnetic microparticles was constructed. ResultsCompound D could combine with the complementary short chain of the aptamer (CSC-Apt) of AFP to form the D/CSC-Apt complex and realize the fluorescence enhancement of Compound D. Then, magnetic particles modified by the Apt of AFP (Apt-Fe3O4) were prepared. When AFP (or nontarget substance) and D/CSC-Apt were successively added to the Apt-Fe3O4 solution, Apt-Fe3O4 selectively bound to AFP or the D/CSC-Apt complex. Magnetic separation technology showed the changes in the fluorescence intensity of the supernatant. The research results revealed a good linear relationship between the changes in the fluorescence intensity of the supernatant and concentration of AFP within the concentration range of 10–10000 pg mL−1. The proposed aptasensor could achieve high-sensitivity and high-specificity detection of AFP, and its limit of detection was 3 pg mL−1 (S/N = 3). Significance and noveltyThe sensor combines the advantages of high selectivity of Apt, high sensitivity of fluorescence analysis, AIE effect and good water solubility of Compound D, and rapid separation using magnetic separation technology. And it can be directly used for the detection of AFP in actual serum samples with high accuracy, whereas most of the methods reported in the literature can only detect AFP in spiked serum samples.

Two birds with one stone: A universal design and application of signal-on labeled fluorescent/electrochemical dual-signal mode biosensor for the detection of tetracycline residues in tap water, milk and chicken

An ingenious and universal design of fluorescent/electrochemical dual-signal mode sensing platform was constructed for the sensitive, selective and accurate detection of tetracycline (TET). Apt-functionalized nano-magnetic beads (Fe3O4-Apt) as capture probe, Apt-complementary short-chain functionalized fluorescent MOF loaded with methylene blue (MB) (cDNA-MOF-MB) as dual-signal tag were prepared. The sensing platform (Fe3O4-Apt/cDNA-MOF-MB) was formed based on the base complementary pairing of Apt and cDNA. With the help of Apt for target recognition, together with magnetic separation technology, a dual-signal mode biosensor was constructed. The dual-signal mode biosensor exhibited a wide linear concentration range from 1.00 × 10−9 g/mL to 1.00 × 10−4 g/mL with a low limit of detection (LOD) of 1.69 × 10−10 g/mL (fluorescence mode assay) and 1.15 × 10−10 g/mL (electrochemical mode assay). The proposed biosensor had been successfully applied to the determination of TET content in real samples with satisfactory recoveries (94.99–101.30%).