Magnetic Enrichment Research Articles

Investigation of physicochemical characterization and magnetic enrichment of iron ore from Sidi Maarouf deposit

The establishment of a new metallurgical complex in Bellara, located in El-Milia in the Jijel region, is geographically advantageous due to its proximity to the Sidi Maarouf deposit (Algeria). This proximity has been a fundamental motivation for the completion of the current study. The object of research is the quality of iron products from Sidi Maarouf. The research is aimed at developing a treatment process aimed at improving the quality of iron products from Sidi Maarouf, while reducing the impurities of quartz and clay present in this ore. This approach will be based on an approved technological treatment scheme, implemented through an experimental approach to ensure reliable results that meet the requirements of the steel industry. The problem issue revolves around the difficulties encountered in the production of steels due to the natural characteristics of the raw material. In the absence of a physico-chemical characterization of the Sidi Maarouf iron ore deposit, samples taken undergo a series of thorough analyses, including microscopic examinations, X-ray diffraction (XRD), as well as additional chemical analyses using X-ray fluorescence (XRF). The identified minerals are predominantly composed of hematite in terms of iron. As for the gangue, it is mainly composed of calcite and quartz. Through to the pre-treatment process involving washing, we have successfully removed lightweight particles, resulting in a concentrate containing dense particles. This approach was crucial in achieving satisfactory results during the high-intensity dry magnetic separation. As a result of the research it is shown that the enrichment of the Sidi Maarouf iron ore through high-intensity dry magnetic separation, a final concentrate was obtained with a Fe2O3 content exceeding 67 %, along with a significant reduction in silica impurities to 0.92 % and alumina to 0.77 %. It was concluded that this concentrate, derived from the -1+0.5 mm fraction and obtained under a current intensity of 12 A, meets the requirements of the steel industry. Following the work carried out, it is found that the methods of valorization of iron ore through mineralogical processes consistently require a high level of efficiency and performance in terms of equipment and characterization of the products obtained. In the future, iron ore processing will be conducted using innovative methods, integrating advanced technologies to enhance its characteristics while adopting environmentally friendly practices.

Verification of a method using magnetic bead enrichment and nucleic acid extraction to improve the molecular detection of bacterial contamination in blood components.

Bacterial contamination of blood products poses a significant risk in transfusion medicine. Platelets are particularly vulnerable to bacterial growth because they must be stored at room temperature with constant agitation for >5 days. The limitations of bacterial detection using conventional methods, such as blood cultures and lateral flow assays, include the long detection times, low sensitivity, and the requirement for substantial volumes of blood components. To address these limitations, we assessed the performance of a bacterial enrichment technique using antibiotic-conjugated magnetic nanobeads (AcMNBs) and real-time PCR for the detection of bacterial contamination in plasma. AcMNBs successfully captured >80% of four bacterial strains, including Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Klebsiella pneumoniae, in both plasma and phosphate-buffered saline. After 24-h incubation with bacterial enrichment, S. aureus and B. cereus were each detected at 101 CFU/mL in all trials (5/5), E. coli at 101 CFU/mL in 1/5 trials, and K. pneumoniae at 10² CFU/mL in 4/5 trials. Additionally, without incubation, the improvement was also achieved in samples with bacterial enrichment, S. aureus at 10² CFU/mL and B. cereus at 101 CFU/mL in 1/5 trials each, E. coli at 10³ CFU/mL in 3/5 trials, and K. pneumoniae at 10¹ CFU/mL in 2/5 trials. Overall, the findings from this study strongly support the superiority of bacterial enrichment in detecting low-level bacterial contamination in plasma when employing AcMNBs and PCR.IMPORTANCEThe study presents a breakthrough approach to detect bacterial contamination in plasma, a critical concern in transfusion medicine. Traditional methods, such as blood cultures and lateral flow assays, are hampered by slow detection times, low sensitivity, and the need for large blood sample volumes. Our research introduces a novel technique using antibiotic-conjugated magnetic nanobeads combined with real-time PCR, enhancing the detection of bacteria in blood products, especially platelets. This method has shown exceptional efficiency in identifying even low levels of four different species of bacteria in plasma. The ability to detect bacterial contamination rapidly and accurately is vital for ensuring the safety of blood transfusions and can significantly reduce the risk of infections transmitted through blood products. This advancement is a pivotal step in improving patient outcomes and elevating the standards of care in transfusion medicine.

Recombinant mannan-binding lectin magnetic beads increase pathogen detection in immunocompromised patients

The microbiological diagnosis of infection for hematological malignancy patients receiving chemotherapy or allogeneic hematopoietic stem cell transplantation (allo-HSCT) patients relies primarily on standard microbial culture, especially blood culture, which has many shortcomings, such as having low positive rates, being time-consuming and having a limited pathogenic spectrum. In this prospective observational self-controlled test accuracy study, blood, cerebrospinal fluid (CSF), and bronchoalveolar lavage fluid (BALF) samples were collected from chemotherapy or allo-HSCT patients with clinical symptoms of infections who were hospitalized at Peking University First Hospital. Possible pathogens were detected by the method based on recombinant mannan-binding lectin (MBL) magnetic bead enrichment (M1 method) and simultaneously by a standard method. The analytical sensitivity of M1 method was close to that of standard culture method. Besides, the turn-around time of M1-method was significantly shorter than that of standard culture method. Moreover, the M1 method also added diagnostic value through the detection of some clinically relevant microbes missed by the standard method. M1 method could significantly increase the detection efficiency of pathogens (including bacteria and fungi) in immunocompromised patients.Key points• The detection results of M1-method had a high coincidence rate with that of standard method• M1 method detected many pathogens which had not been found by standard clinic method

Real-time and visual detection of viable Salmonella in milk from remote pasture via IMS-LAMP-NALFS

Salmonella is a prevalent foodborne pathogen commonly found in dairy products. Controlling the presence of Salmonella during dairy product production is of utmost concern due to the potential for contamination at any stage of the production chain, particularly at the source. Moreover, the unique location of pastures and limited testing resources further highlight the necessity of establishing a rapid and precise detection method to ensure milk quality control and enhance overall farm safety. To address these issues, in this study, we constructed a method as well as a portable toolbox for rapid on-site detection of Salmonella. The method involves immunomagnetic separation (IMS) using streptavidin-coupled magnetic nanoparticles and biotinylated antibodies. The reaction conditions for magnetic capture and enrichment of Salmonella were optimized to efficiently remove matrix interference from milk and enhance detection sensitivity. Additionally, an improved propidium monoazide (PMAxx) treatment was employed to eliminate false positive results caused by dead bacteria. This treatment was combined with loop-mediated isothermal amplification (LAMP) and nucleic acid lateral flow strip (NALFS) (LAMP-NALFS) for on-site detection of viable bacteria in milk. The resulting IMS-LAMP-NALFA assay achieved rapid and sensitive detection of viable Salmonella, with a detection sensitivity of 1 × 102 CFU/mL in milk samples, completed within 90 min under optimal conditions. Based on this achievement, a portable toolbox was designed for easy transportation and on-site testing in pastures. It is equally applicable for rapid detection of viable Salmonella contamination in food products in resource-limited areas such as pastures, where the observed detection rate of Salmonella in unpasteurized raw milk was 7.93 % (28 out of 353 samples tested). Consequently, the IMS-LAMP-NALFA method and the associated portable toolbox represent highly effective means of enhancing the detection of viable Salmonella in dairy products.

Efficient magnetic enrichment cascade single-step RPA-CRISPR/Cas12a assay for rapid and ultrasensitive detection of Staphylococcus aureus in food samples

Staphylococcus aureus (S. aureus) is a prevalent foodborne pathogen that could cause severe food poisoning. Thus, rapid, efficient, and ultrasensitive detection of S. aureus in food samples is urgently needed. Here, we report an efficient magnetic enrichment cascade single-step recombinase polymerase amplification (RPA)-CRISPR/Cas12a assay for the ultrasensitive detection of S. aureus. Magnetic beads (MBs) functionalized with S. aureus-specific antibodies were initially used for S. aureus enrichment from the complex matrix, with 98% capture efficiency in 5 min and 100-fold sensitivity improvement compared with unenriched S. aureus. Next, a single-step RPA-CRISPR/Cas12a-based diagnostic system with optimized extraction-free bacteria lysis was constructed. This assay could detect as low as 1 copy/μL (five copies/reaction) of extracted DNA template and 10 CFU/mL of S. aureus within 40 min. Furthermore, the assay could effectively detect S. aureus in real food samples such as lake water, orange juice, pork, and lettuce, with concordant results to qPCR assays. The proposed cascade signal-amplification assay eliminates the need for lengthy bacterial culture and complex sample preparation steps. Hence, the proposed assay shows great application potential for rapid, efficient, and ultrasensitive detection of pathogens in real food samples.

2D Film-Like Magnetic SERS Tag with Enhanced Capture and Detection Abilities for Immunochromatographic Diagnosis of Multiple Bacteria.

Here, a multiplex surface-enhanced Raman scattering (SERS)-immunochromatography (ICA) platform is presented using a graphene oxide (GO)-based film-like magnetic tag (GFe-DAu-D/M) that effectively captures and detects multiple bacteria in complex specimens. The 2D GFe-DAu-D/M tag with universal bacterial capture ability is fabricated through the layer-by-layer assembly of one layer of small Fe3O4 nanoparticles (NPs) and two layers of 30nm AuNPs with a 0.5nm built-in nanogap on monolayer GO nanosheets followed by co-modification with 4-mercaptophenylboronic acid (MPBA) and 5,5'-dithiobis-(2-nitrobenzoic acid).The GFe-DAu-D/M enabled the rapid enrichment of multiple bacteria by MPBA and quantitative analysis of target bacteria on test lines by specific antibodies, thus achieving multiple signal amplification of magnetic enrichment effect and multilayer dense hotspots and eliminating matrix interference in real-world applications. The developed technology can directly and simultaneously diagnose three major pathogens (Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella typhimurium) with detection limits down to the level of 10cellsmL-1. The good performance of the proposed method in the detection of real urinary tract infection specimens is also demonstrated, suggesting the great potential of the GFe-DAu-D/M-ICA platform for the highly sensitive monitoring of bacterial infections or contamination.

A simultaneous strategy with multiple-signal amplification and self-calibration for ultrasensitive assay of miRNA-21 based on 3D MNPs-IL-rGO-AuNPs

MicroRNA-21 (miRNA-21) is a significant biomarker for the development and progression of diverse cancers but is present in relatively low concentrations. Detecting such low-abundance molecules accurately can be challenging, especially in early-stage cancers where the concentration may be even lower. Herein, a self-calibration biosensing platform based on 3D novel MNPs-IL-rGO-AuNPs nanocomposites was successfully established for the ultrasensitive detection of miRNA-21. Duplex-specific nuclease (DSN) was introduced to recognize perfectly matched duplexes and trigger target recycling, enhancing the specificity and sensitivity of the biosensor. DSN-assisted target recycling, in conjunction with magnetic separation enrichment and high-performance MNPs-IL-rGO-AuNPs, collectively formed a multiple-signal amplification strategy. The obtained biosensor could output dual signals in both electrochemical and fluorescent modes, enabling self-correcting detection to enhance the accuracy. The obtained dual-mode biosensor prepared exhibited a wide detection range from 5 fM to 100 nM with a remarkably low LOD of 1.601 fM. It accomplished the sensitive evaluation of miRNA-21 in total RNA extracted from various human cancer cell lines and normal cell lines. Additionally, the greatly satisfactory outcomes in the analysis of human serum samples suggested that the proposed biosensor was a powerful screening candidate in early clinical diagnosis of cancer.

Peptide-Loaded HLA Class I Tetramer-Associated Magnetic Bead-Based Enrichment of HBV-Specific CD8+ T Cells.

HBV-specific CD8+ T cells are only present at the low frequency during chronic infection. Thus, they are often undetectable by conventional ex vivo staining methods using peptide-loaded HLA class I tetramers. Detection sensitivity can be increased by magnetic bead-based enrichment strategies following staining with peptide-loaded HLA class I tetramers. Additionally, some downstream applications like e.g., single cell RNA sequencing of virus-specific CD8+ T cells may also require a pre-enrichment step to increase the frequency of the cells of interest. For this, peptide-loaded HLA class I tetramers-associated magnetic bead-based enrichment is also a suitable method.

CyTOF Intracellular Cytokine Assays for Antigen-Specific T Cells.

T cells specific for a single antigen tend to be rare, even after expansion of memory cells. They are commonly detected by in vitro stimulation with peptides or protein, followed by staining for intracellular cytokines. In this protocol, CyTOF® mass cytometry is used to collect single-cell data on a large number of cytokines/chemokines, as well as cell-surface proteins that characterize T cells and other immune cells. A method for magnetic bead enrichment of antigen-stimulated T cells, based on their expression of CD154 and CD69, is also included. Coupling magnetic enrichment with highly multiparameter mass cytometry, this method enables the ability to dissect the frequency, phenotype, and function of antigen-specific T cells in greater detail than previously possible. Rare cell subsets can be examined, while minimizing run times on the CyTOF.

A LAMP-CRISPR/Cas12b rapid detection platform for canine parvovirus detection.

Canine parvovirus (CPV) is one of the main pathogens causing toxic diarrhea in Chinese dogs, is the cause of large-scale epidemic of dogs, and poses a great threat to the dog industry in China. Rapid, sensitive, and specific CPV testing facilitates the timely diagnosis and treatment of sick dogs. The aim of this study was to build a LAMP-CRISPR/Cas12b platform for CPV detection. The loop mediated isothermal amplification (LAMP) technique was combined with CRISPR-Cas12b analysis to establish a "two-step" and "one-tube" CRISPR/Cas12b rapid CPV method, respectively. The detection system was constructed with specific LAMP primers and single guide RNA (sgRNA) for the highly conserved short fragment of the CPV gene, which could be detected within 1 h without cross-reaction with the other viruses causing canine diarrhea. The detection limits of both "two-step" and "one-tube" CRISPR/Cas12b reactions were 10-1 copies per μL, which was 100 times more sensitive than qPCR and LAMP. In order to achieve point-of-care testing (POCT) of CPV, a one-tube LAMP-CRISPR/Cas12b nucleic acid extraction and detection platform based on magnetic nanoparticle enrichment technology was established to achieve "sample in-result out". The results of this method for simulated samples were compared with those of quantitative real-time PCR; the results showed 100% consistency, and the time was shorter, which could be used to detect the diseased dogs earlier and provide a basis for clinical diagnosis. The LAMP-CRISPR/Cas12b method established in this study provides a sensitive and specific method for rapid detection of CPV, and provides technical support for rapid diagnosis of CPV.

A new strategy for RRS-based determination of phosphate with a bifunctional Fe3O4 magnetic nanoparticle surface molecularly imprinted polydopamine probe.

In this paper, a magnetic nanoparticle surface molecularly imprinted polydopamine RRS probe Fe3O4@MIP was prepared using phosphomolybdic acid (PMo) as the template, Fe3O4 magnetic nanoparticles as the substrate and dopamine hydrochloride (PD) as the monomer and crosslinking agent for the determination of PO43-. Under acidic conditions, phosphomolybdic acid is formed by the reaction of PO43- with ammonium molybdate (MSA), which can be imprinted with the Fe3O4@MIP probe surface and reduced to phosphomolybdic blue (PMoB) by ascorbic acid (Aa). Strong resonance Rayleigh scattering energy transfer (RRS-ET) occurs between the probe and PMoB, resulting in a decrease in the RRS signal value. A new, simple and selective RRS method for the determination of PO43- in water samples was developed. The linear range of this method is 1-22.5 μmol L-1, and the detection limit (DL) is 0.49 μmol L-1. Furthermore, the magnetic enrichment ability of Fe3O4@MIP is discussed. Experimental data show that even 0.2 μmol L-1 of phosphate can be detected within a 20% error range.

Colourimetric and SERS dual-mode aptasensor using Au@Ag and magnetic nanoparticles for the detection of Campylobacter jejuni

A dual-mode aptasensor has been developed for the effective detection of Campylobacter jejuni (C. jejuni), a major cause of gastrointestinal disease worldwide. The aptasensor utilizes nanoparticles, specifically a core-shell structure consisting of gold and silver (Au@Ag NPs), along with magnetic nanoparticles (MNPs). When Campylobacter jejuni is introduced, “Au@Ag NPs-Aptamer-Campylobacter jejuni-Aptamer-MNPs” sandwich complexes are formed due to the high affinity of the aptamer for the bacterial surface membrane proteins. The dual-mode aptasensor can magnetically enrich the sample in just 15 min, and the presence of Campylobacter jejuni is determined by observing a color change. Additionally, the concentration of Campylobacter jejuni can be quantified using surface-enhanced Raman spectroscopy (SERS) and standard curves. This results in a wider linear range (1.8 × 101–108 CFU/mL) under optimal conditions, a lower limit of detection (6 CFU/mL), and a higher selectivity for the detection of bacteria compared to previously reported sensors. Compared with traditional microbial culture counting methods, the dual-mode aptasensor does not require Raman reporters. The physical action of magnetic enrichment, along with the application of Au@Ag NPs, improves the accuracy of the dual-mode aptasensor, offering the advantages of convenience and high sensitivity. Moreover, by utilizing different types of aptamers, this aptasensor can be modified to detect a wider range of harmful pathogens in various environments.

MNAzyme catalyzed signal amplification-mediated lateral flow biosensor for portable and sensitive detection of mycotoxin in food samples.

Here, an enzyme-free lateral flow aptasensor was designed by target-induced strand-displacement effect and followed by the activation of multi-component nucleic acid enzyme (MNAzyme)-mediated cleavage to enable rapid and portable ochratoxin A (OTA) detection. The substrate was prepared as an oligonucleotide strand modified with magnetic beads (MB) and human chorionic gonadotropin (hCG). The interaction of OTA with the aptamer induces the release of blocking DNA, which hybridized with three separated subunits of DNA, forming a sequence-specific MNAzyme catalytic core. This core subsequently initiated an enzyme-free MNAzyme cleavage reaction in the presence of the Mg2+ cofactor, cleaving a special substrate and releasing both the incomplete MNAzyme catalytic core and hCG-DNA probe. The incomplete MNAzyme catalytic core was then recognized by substrates once again, triggering a cascade recycling cleavage and resulting in the generation of a larger number of hCG-DNA probes. After magnetic enrichment, the free hCG-DNA probes flow through the pregnancy test strip (PTS) to the T line, generating a colorimetric readout that unequivocally confirms the presence of the target OTA. This work leverages the efficient enzyme-free cleavage amplification of MNAzyme and the PTS-based portable detection device, presenting a biosensing strategy with significant potential for sensitive and portable OTA detection. This method exhibited remarkable sensitivity and selectivity for OTA detection, boasting a detection limit of 5nM. The present study successfully demonstrated the practical application of this method on real samples, offering a viable alternative for rapid and portable detection of mycotoxins.

Fe3O4-WO3−X@AuNPs for magnetic separation, enrichment and surface-enhanced Raman scattering analysis all-in-one of albendazole and streptomycin in meat samples

Rapid and selective quantification of trace residuals in complex samples is a great challenge for fast analysis. Herein, we developed magnetic Fe3O4-WO3−X @AuNPs hybrid sensor for efficient surface-enhanced Raman scattering(SERS) quantifications of albendazole(ABZ) and streptomycin(SPT) in meat samples. Fe3O4-WO3−X @AuNPs was prepared by hydrothermal method with CTAB assistance and in-situ distributing method. Fe3O4-WO3−X @AuNPs showed good sensing performance: SERS activity with enhancement factor of 6.3 × 107 for crystal violet, separation/enrichment capacity within 15 min for targets, selectivity to ABZ and SPT, stability with RSDs less than 4.5%(n = 25) for one intra-batch and 5.6%(n = 15) for different batches. Fe3O4-WO3−X @AuNPs integrated magnetic enrichment, fast clean-up separation, and synergistic enhancement of plasmons and charge transfer, which endowed it with good sensitivity, anti-interference, and accuracy for real sample analysis. SERS methods of ABZ and SPT were established，and limits of detection were 12.5 μg/L(ABZ) and 11.6 μg/L(SPT). ABZ was found in fish sample with recoveries of 90.1%− 105.0%, and SPT was found in chicken sample with recoveries of 86.2%− 101.8%. Entire analysis process completed within 27 min(ABZ) and 32 min(SPT), showing great potential for rapid quantification of different veterinary drugs residuals during food safety analysis.

Human CD4+CD25+ T cells expressing a chimeric antigen receptor against aberrant superoxide dismutase 1 trigger antigen-specific immunomodulation

Background aimsAmyotrophic lateral sclerosis (ALS) is a fatal disease associated with motor neuron degeneration, accumulation of aggregated misfolded proteins and neuroinflammation in motor regions of the central nervous system (CNS). Clinical trials using regulatory T cells (Tregs) are ongoing because of Tregs’ immunomodulatory function, ability to traffic to the CNS, high numbers correlating with slower disease in ALS and disease-modifying activity in ALS mouse models. In the current study, a chimeric antigen receptor (CAR) was developed and characterized in human Tregs to enhance their immunomodulatory activity when in contact with an ALS protein aggregate. MethodsA CAR (DG05-28-3z) consisting of a human superoxide dismutase 1 (hSOD1)-binding single-chain variable fragment, CD28 hinge, transmembrane and co-stimulatory domain and CD3ζ signaling domain was created and expressed in human Tregs. Human Tregs were isolated by either magnetic enrichment for CD4+CD25hi cells (Enr-Tregs) or cell sorting for CD4+CD25hiCD127lo cells (FP-Tregs), transduced and expanded for 17 days. ResultsThe CAR bound preferentially to the ALS mutant G93A-hSOD1 protein relative to the wild-type hSOD1 protein. The CAR Tregs produced IL-10 when cultured with aggregated G93A-hSOD1 proteins or spinal cord explants from G93A-hSOD1 transgenic mice. Co-culturing DG05-28-3z CAR Tregs with human monocytes/macrophages inhibited production of tumor necrosis factor alpha and reactive oxygen species. Expanded FP-Tregs resulted in more robust Tregs compared with Enr-Tregs. FP-Tregs produced similar IL-10 and less interferon gamma, had lower Treg-specific demethylated region methylation and expressed higher FoxP3 and CD39. ConclusionsTaken together, this study demonstrates that gene-modified Tregs can be developed to target an aggregated ALS-relevant protein to elicit CAR-mediated Treg effector functions and provides an approach for generating Treg therapies for ALS with the goal of enhanced disease site-specific immunomodulation.

Smartphone-based pH responsive 3-channel colorimetric biosensor for non-enzymatic multi-antibiotic residues.

Antibiotic residues in animal-derived food pose a risk to food safety and human health. Here, a smartphone-based pH-responsive 3-channel colorimetric biosensor is constructed for rapid detection of non-enzymatic multi-antibiotic residues in milk. In this system, a magnetic separation and enrichment approach is designed to specifically capture different antibiotic residues in complex environment. Indicators loaded on polydopamine-silver nanoparticles with excellently pH responsive visualization properties are utilized to ensure the high sensitivity of detection system. Moreover, smartphones are introduced to fulfill the demand for portable and on-site inspection of practical applications. It achieves simultaneous detection of oxytetracycline, kanamycin and streptomycin in the linear range of 1-105 pg/mL with detection limits of 0.085, 0.168, and 0.307pg/mL, respectively. The practicality of the reported multi-antibiotic residues detection system is successfully demonstrated and evaluated challenging milk samples. Therefore, this system demonstrates the wide applications in multi-antibiotic residue analysis and food safety guarantee.

Recyclable magnetic nanoparticles combined with TiO2 enrichment and “Off” to “On” SERS assay for sensitive detection of alkaline phosphatase

As an important enzyme in human tissues, abnormally alkaline phosphatase (ALP) is strongly associated with many diseases, particularly breast and prostate cancer. In this study, we proposed a rapid and sensitive surface-enhanced Raman scattering (SERS)-based biosensor for ALP detection. The biosensor utilized Fe3O4@Au@TiO2 nanoparticles (FAT NPs) as magnetic separation and enrichment materials to enrich grafted mediator Ag-4-mercaptophenylboronic acid (4-MPBA)-ascorbic acid 2-phosphate (AAP) NPs to form FAT-(AAP-4-MPBA-Ag) NPs, and 5,5′-dithiobis-(2-nitrobenzoic acid) (DTNB) was used as the internal standard tag molecule to prepare Au@DTNB@Ag as the signal source. The phosphate group in AAP was cleaved by ALP to form ascorbic acid (AA), which acts as a receptor for the boric acid to adsorb the 4-MPBA-Au@DTNB@Ag NPs. When the switch was “Off” to “On”, the Au@DTNB@Ag NPs were used to significantly improve the sensitivity of the proposed SERS platform, enabling detection as low as 1.17U/L of target ALP with a good linear range (R 2 = 0.991) of 2–10 U/L. Furthermore, the platform successfully detected ALP from 2 % human serum. The recoveries were 99.5–106 %. In addition, FAT-(AAP-4-MPBA-Ag) NPs could be transformed into FAT NPs to achieve recyclability by ultrasonication in acidic environments. Overall, this sensitive and fast SERS platform has promising potential for accurate and efficient identification of ALP from human serum.

Bio-inspired Janus microcarriers with sequential actives release for bone regeneration

Growth factor therapy is an effective treatment strategy for bone repair. Research in this field aims to develop functional biomaterials for delivering multiple growth factors in a temporally controllable way and thus improving the therapeutic effect. Herein, inspired by natural bone healing mechanisms that involves early-stage angiogenesis and later-stage osteogenesis, we develop a novel type of Janus microcarriers with sequential actives release ability from microfluidic electrospray for bone regeneration. The Janus microcarriers contain two distinct hemispheres consisting of hyaluronic acid methacryloyl (HAMA) and gelatin methacryloyl (GelMA) hydrogel, respectively. Vascular endothelial growth factor (VEGF) and bone morphogenetic protein 2 (BMP2) are compartmentalized in different hemispheres of the microcarriers and released sequentially, in a way mimicking the natural bone repair process. In addition, magnetic Fe3O4@SiO2 nanoparticles are doped in the microcarriers to facilitate magnetic enrichment and localization of the microcarriers in the bone defect site. Moreover, the GelMA hemisphere facilitates cell migration to the defect site, and the HAMA hemisphere reduces the risk of tissue adhesion. In vivo experiments demonstrate that the Janus microcarriers can effectively promote bone regeneration by coordinating angiogenesis and osteogenesis. We believe this work provides a new approach for the development of novel smart drug vehicles and treatment of bone defects.

A magnetic control enrichment technique combined with terahertz metamaterial biosensor for detecting SARS-CoV-2 spike protein

The highly contagious SARS-CoV-2 virus, responsible for the COVID-19 pandemic continues to pose significant challenges to public health. Developing new methods for early detection and diagnosis is crucial in combatting the disease, mitigating its impact and be prepared for future challenges in pandemic diseases. In this study, we propose a terahertz (THz) biosensing technology that capitalizes on the properties of THz metamaterial in conjunction with magnetic nanoparticles. This approach can accurately identify the SARS-CoV-2 spike protein by pinpointing its location on the THz resonance sources grooved surface. The magnetic nanoparticles are employed to selectively bind with target molecules, and migrate towards the THz metamaterial unit cell when exposed to an applied magnetic field. The presence of target molecules in to the metamaterial variation in the frequency, amplitude, and phase of the resonance response, thus enabling swift, accurate and sensitive detection. To assess the effectiveness of the proposed technique, we have conducted a comparative analysis between real samples on platforms controlled by magnetic manipulation and those without the control. It was confirmed that the proposed THz sensing method demonstrated a linear detection range spanning from 0.005 ng mL−1 to 1000 ng mL−1 with a detection limit of 0.002 ng mL−1. Furthermore, it exhibited a frequency shift of 24 GHz and a stability index of 95%. The THz biosensing technique may pave a new avenue in identifying and preempting the spread of potential pandemic diseases.

Magnetic ZnFe2O4 composite advances SERS assay for Patent blue V

BackgroundPatent blue V (PbV) an Azo colorant because of its high toxicity to children has been severely limited in food industry. However, frequently the abuse of PbV in some artificial foods is still exposed by media. Current methods for the detection of PbV have to perform tedious pre-processing and the detection sensitivity and speed are required to be further improved. ResultsIn this work, we immobilize gold nanoparticles (Au NPs) on the surface of ZnFe2O4 with aid of Inositol hexaphosphate (IP6) to prepare a novel magnetic surface-enhanced Raman scattering (SERS) substrate (designated as ZnFe2O4–IP6–Au NPs) for rapid detection of PbV in beverages. Synergistic effect of magnetic enrichment, magnetic inducing improvement effect (MIIE) and efficient charge transfer (CT) enables ZnFe2O4–IP6–Au NPs-based SERS assay to achieve limit of detection of PbV down to 1.31 × 10−8 mol/L and a concentration linear relationship ranging from 8.6 × 10−4 to 8.6 × 10−8 mol/L. The detection recoveries for PbV in beverages locate in the range from 98.1 to 102.5 %, meaning the feasibility of method. In addition, the presence of IP6 protection greatly improves the storage stability of ZnFe2O4–IP6–Au NPs. SignificanceZnFe2O4–IP6–Au NPs substrates with excellent SERS performance could on-site, rapidly and sensitively detect PbV. As a perspective, magnetic-composite-based SERS assay has great scenario in food safety by using portable Raman spectrometer.