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CYP2C19*3 enzyme plays a pivotal role in drug metabolism and is tightly regulated by the CYP2C19*3 gene. Therefore, quantification of CYP2C19*3 gene holds paramount importance for achieving personalized medication guidance in precision medicine. In this project, the magnetic electrochemical biosensors were constructed for the ultra-sensitive detection of CYP2C19*3 gene. Employing magnetic α-Fe2O3/Fe3O4@Au as the matrixes for signal amplification, CYP2C19*3 complementary chains (c-ssDNA) were bound to their surfaces through gold-sulfur bonds with subsequent specific sites blockade by bovine serum albumin (BSA) to form the α-Fe2O3/Fe3O4@Au/c-ssDNA/BSA biosensors. This design enabled efficient biosensors separation, target gene capture, and self-assembly on the electrode surface, enhancing the response signal. The biosensors exhibited excellent capture capabilities with a wide linear range (1 pM-1 µM), a low detection limit of 0.2710 pM, a quantitation limit of 0.9033 pM, reproducibility with an RSD value of 1.26 %, and stable storage for at least one week. The RSD value of CYP2C19*3 in serum samples consistently remained below 4.5 %, with a recovery rate ranging 95.52 % from 102.71 %. Moreover, the target gene could be accurately identified and captured in a mixed system of multiple nucleotide mutants of the CYP2C19*3 gene, suggesting a promising applicability and popularization.

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Organic-inorganic nanocomposites have the potential to be used in photovoltaic materials due to their eco-friendliness, suitable band gaps, and high stability. In this work, we integrated gold and Fe3O4 magnetic nanoparticles with poly-m-amino benzene sulfonic (m-ABS) to synthesize Fe3O4@Au@poly-(m-aminobenzenesulfonic acid) (Fe3O4@Au@m-ABS) magneto-plasmonic nanoparticles (MPNPs) to enhance the performance of the organic photovoltaic (OPV). These MPNPs exhibit broad UV-Vis absorption and a low band gap of 2.878 eV, enhancing their suitability for photovoltaic applications. The MPNPs were introduced into the ZnO electron transporting layer (ETL) and active layer to investigate the influence of MPNPs on the power conversion efficiency (PCE) of the OPVs. When 0.1 vol% MPNPs were incorporated in the ETL, the OPVs achieved a PCE of 14.24% and a fill factor (FF) of 69.10%. On the other hand, when 0.1 vol% MPNPs were incorporated in the active layer, the OPVs showed a PCE of 14.11% and an FF of 68.83%. However, the OPVs without MPNPs only possessed a PCE of 13.15% and an FF of 63.69%. The incorporation of MPNPs increased the PCE by 8.3% in the OPV device. These findings suggest that Fe3O4@Au@m-ABS MPNPs are promising nanocomposite materials for enhancing the performance of OPVs.

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In radiotherapy, metallic nanoparticles are of high interest in the fight against cancer for their radiosensitizing effects. This study aimed to evaluate the ability of core-shell Fe3O4@Au nanoparticles to potentiate the irradiation effects on redox-, pro-inflammatory markers, and cell death of A549 human pulmonary cancer cells. The hybrid Fe3O4@Au nanoparticles were synthesized using green chemistry principles by the sonochemistry method. Their characterization by transmission electron microscopy demonstrated an average size of 8 nm and a homogeneous distribution of gold. The decreased hydrodynamic size of these hybrid nanoparticles compared to magnetite (Fe3O4) nanoparticles showed that gold coating significantly reduced the aggregation of Fe3O4 particles. The internalization and accumulation of the Fe3O4@Au nanoparticles within the cells were demonstrated by Prussian Blue staining. The reactive oxygen species (ROS) levels measured by the fluorescent probe DCFH-DA were up-regulated, as well as mRNA expression of SOD, catalase, GPx antioxidant enzymes, redox-dependent transcription factor Nrf2, and ROS-producing enzymes (Nox2 and Nox4), quantified by RT-qPCR. Furthermore, irradiation coupled with Fe3O4@Au nanoparticles increased the expression of canonical pro-inflammatory cytokines and chemokines (TNF-α, IL-1ß, IL-6, CXCL8, and CCL5) assessed by RT-qPCR and ELISA. Hybrid nanoparticles did not potentiate the increased DNA damage detected by immunofluorescence following the irradiation. Nevertheless, Fe3O4@Au caused cellular damage, leading to apoptosis through activation of caspase 3/7, secondary necrosis quantified by LDH release, and cell growth arrest evaluated by clonogenic-like assay. This study demonstrated the potential of Fe3O4@Au nanoparticles to potentiate the radiosensitivity of cancerous cells.

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Staphylococcus aureus (S. aureus) poses a serious threat to global public health, necessitating the establishment of rapid and simple tools for its accurate identification. Herein, we developed a terahertz (THz) metamaterial biosensor based on aptamer-functionalized Fe3O4@Au nanocomposites for quantitative S. aureus assays in different clinical samples. Fe3O4@Au@Cys@Apt has the dual advantages of magnetism and a high refractive index in the THz range and was used to rapidly separate and enrich target bacteria in a complex environmental solution. Furthermore, conjugation to the nanocomposites significantly increased the resonance frequency shift of the THz metamaterial after target loading. Our results showed that the shifts in the metamaterial resonance frequency were linearly related to S. aureus concentrations ranging from 1.0 × 103 to 1.0 × 107 CFU/mL, with a detection limit of 4.78 × 102 CFU/mL. The biosensor was further applied to S. aureus detection in spiked human urine and blood with satisfactory recoveries (82.4-109.6%). Our approach also demonstrated strong concordance with traditional plate counting (R2 = 0.99306) while significantly lowering the analysis time from 24 h to <1 h. In conclusion, the proposed biosensor can not only perform culture-free and extraction-free detection of target bacteria but can also be easily extended to the determination of other pathogenic bacteria, rendering it suitable for various bacteria-related disease diagnoses.

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A "turn-on" aptasensor for label-free and cell-free EpCAM detection was constructed by employing magnetic α-Fe2O3/Fe3O4@Au nanocomposites as a matrix for signal amplification and double-stranded complex (SH-DNA/Apt probes) immobilization through Au-S binding. α-Fe2O3/Fe3O4@Au could be efficiently assembled into uniform and stable self-assembly films via magnetic-induced self-assembly technique on a magnetic glassy carbon electrode (MGCE). The effectiveness of the platform for EpCAM detection was confirmed through differential pulse voltammetry (DPV). Under optimized conditions, the platform exhibited excellent specificity for EpCAM, and a strong linear correlation was observed between the current and the logarithm of EpCAM protein concentration in the range 1 pg/mL-1000 pg/mL (R2 = 0.9964), with a limit of detection (LOD) of 0.27 pg/mL. Furthermore, the developed platform demonstrated good stability during a 14-day storage test, with fluctuations remaining below 93.33% of the initial current value. Promising results were obtained when detecting EpCAM in spiked serum samples, suggesting its potential as a point-of-care (POC) testing.

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A low-cost and reliable analytical method based on the combination of a newly designed Fe3O4@Au as peroxidase mimetics, supported on smartphone analysis software package was proposed for the determination of glucose content in food samples. The nanocomposite was prepared by self-assembling technique, and the characterization was carried out using transmission electron microscopy (TEM), Fourier transforms infrared, and X-ray diffractometer. Record the color change of the solution with a smartphone camera and optimize the operation parameters and reaction conditions. A smartphone with a free self-developed app was accustomed live the RGB (red-greenblue) values of color intensity within the Fe3O4@Au system and were processed with Image J software before computationally convert them glucose concentrations. At the optimization experiment, reaction temperature of 60 °C, reaction time of 50 min and the amount of addition of Fe3O4@Au 0.0125 g was the optimal combination of detecting glucose smartphone color detection system. Hereon, the accuracy of the proposed method was evaluated by comparison between smartphone colorimetry and UV-vis spectrophotometer, a linear calibration in the range of 0.25 âˆ¼ 15 mmol/L glucose was obtained with minimum detection limit of 1.83 and 2.25 µmol/L, respectively. The proposed method was applied effectively to the detection of glucose in actual samples. The results were in accordance with the conventional UV-vis spectrophotometer method.

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Fe3O4/Au/porous Au nanohybrids being bi-functional nanoparticles with magnetic properties and high porosity, were synthesized and used for drug delivery. To achieve this purpose, after Fe3O4 nanoparticles synthesis, a gold layer coats them to increase their stability. Then, to improve the loading capacity of Fe3O4/Au nanoparticles, a shell of porous gold was synthesized on the Fe3O4/Au surface by creating an Ag-Au nanohybrid layer on Fe3O4/Au and dissolving the metallic silver atoms in HNO3 (0.01 M). The DLS results show that the synthesized nanohybrid has an average size of 68.0 ± 7.7 nm and a zeta potential of - 28.1 ± 0.2 mV. Finally, doxorubicin (DOX), as a pharmaceutical agent, was loaded onto the Fe3O4/Au/porous Au nanohybrids. The prepared nano-drug enhanced the therapeutic efficacy of DOX on MCF-7 cancer cells compared to the free DOX. These results confirmed a 1.5 times improvement in the antitumor activity of DOX-loaded Fe3O4/Au/porous Au nanohybrids.

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The rapid diagnosis and detection of respiratory bacteria at the early stage can effectively control the epidemic spread and bacterial infection. Here, we designed a rapid, ultrasensitive, and quantitative lateral flow immunoassay (LFA) strip for simultaneous detection of respiratory bacteria S. aureus and S. pneumoniae. In this assay, the surface enhanced Raman scattering (SERS) tags were designed through combining magnetite Raman enhancement nanoparticle Fe3O4@Au/DTNB and recognition element 4-mercaptophenylboronic acid (4-MPBA). Further, 4-MPBA could capture multiple bacteria in a complex environmental solution. Based on the strategies, Fe3O4@Au/DTNB-mediated magnetic enrichment and 4-MPBA-mediated universal capture capabilities improved the detection sensitivity, the limits of detection for S. aureus and S. pneumoniae were as low as 8 and 13 CFU mL-1, respectively, which were more sensitive than those of colloidal gold method. The Fe3O4@Au/DTNB/Au/4-MPBA-LFA also exhibited good reproducibility, excellent specificity, and high recovery rates in sputum samples, indicating its potential application in the detection of respiratory bacteria samples.

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Rapid, simple, sensitive and reliable approaches for biogenic amines quantification in various food samples are essential to food safety. Lateral flow immunoassay (LFIA) has been wildly utilized in point-of-care testing (POCT) owing to its advantage of flexibility and feasibility. Here, we reported a Fe3O4@Au nanoparticles (NPs) (Fe3O4@AuNPs) based multimodal readout LFIA for rapid putrescine (Put) and histamine (His) quantification with a LOD down to 10 and 10 ng/mL in naked eye mode, 2.31 and 4.39 ng/mL in photothermal mode, 0.17 and 0.31 ng/mL in magnetic mode, respectively. Such multi-mode assay has been successfully used to detect Biogenic amines (BAs) in raw aquatic foods, including fish, prawns, beef, and pork, with overall recoveries ranging from 93.68 to 109.34%. Meanwhile, it is easily expanded to detect other typical BAs with high sensitivity by simply replacing antibodies. In view of the multi-signal reading, two quantitative formats, and high sensitivity, it may greatly widen the application of lateral flow detection in food safety.

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Accurate and sensitive analysis of biomarkers is a promising way to provide comprehensive physio-pathological information that is significant for early diagnosis of certain diseases. miRNA is a type of noncoding small RNAs which are involved in the regulation of a number of cellular processes. It has been regarded as an important tumor biomarker. Herein, we have constructed a three-dimensional DNA layer on electrode interface and achieved ladder hybridization chain reaction strategy for the enrichment of electrochemical signals. In addition, duplex-specific nuclease catalyzed amplification is previously performed on magnetic nanocomposites, which further improves the sensitivity for the detection of target miRNA initiator. This approach shows great molecular recognition efficiency as well as cascade signal amplification. The analytical performances are superior. In addition, the identification of cancer cell types according to target biomarker information is achieved and the testing results in clinical serum samples further demonstrate its great potential utility for diagnosis.

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Respiratory viruses usually induced similar clinical symptoms at early infection. Herein, we presented a multichannel surface-enhanced Raman scattering-based lateral flow immunoassay (SERS-based LFA) using high-performance magnetic SERS tags for the simultaneous ultrasensitive detection of respiratory viruses, namely influenza A virus (H1N1), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and respiratory syncytial virus (RSV) in biological samples. As-prepared magnetic SERS tags can directly enrich and capture target viruses without pretreatment of samples, avoiding the interference of impurities in the samples as well as improving the sensitivity. With the capture-detection method, the detection limits of the proposed assay reached 85 copies mL-1, 8 pg mL-1, and 8 pg mL-1 for H1N1, SARS-CoV-2 and RSV, respectively. Moreover, the detection properties of the proposed method for target viruses in throat swab samples were verified, suggesting its remarkable potential for the early and rapid differential diagnosis of respiratory viruses.

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The paper presents the results of a study of iron oxide nanoparticles obtained by chemical coprecipitation, coated (Fe3O4@Au) and not coated (Fe3O4) with gold, which were subjected to thermal annealing. To characterize the nanoparticles under study, scanning and transmission electron microscopy, X-ray diffraction, and Mössbauer spectroscopy on 57Fe nuclei were used, the combination of which made it possible to establish a sequence of phase transformations, changes in morphological and structural characteristics, as well as parameters of hyperfine interactions. During the studies, it was found that thermal annealing of nanoparticles leads to phase transformation processes in the following sequence: nonstoichiometric magnetite (Fe3-γO4) → maghemite (γ-Fe2O3) → hematite (α-Fe2O3), followed by structural ordering and coarsening of nanoparticles. It is shown that nanoparticles of nonstoichiometric magnetite with and without gold coating are in the superparamagnetic state with a slow relaxation rate. The magnetic anisotropy energy of nonstoichiometric magnetite is determined as a function of the annealing temperature. An estimate was made of the average size of the region of magnetic ordering of Fe atoms in nonstoichiometric magnetite, which is in good agreement with the data on the average sizes of nanoparticles determined by scanning electron microscopy.

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The extensive utilization of nanoparticles in cancer therapies has inspired a new field of study called cancer nanomedicine. In contrast to traditional anticancer medications, nanomedicines offer a targeted strategy that eliminates side effects and has high efficacy. With its vast surface area, variable pore size, high pore volume, abundant surface chemistry and specific binding affinity, mesoporous silica nanoparticles (MPSNPs) are a potential candidate for cancer diagnosis and treatment. However, there are several bottlenecks associated with nanoparticles, including specific toxicity or affinity towards particular body fluid, which can cater by architecting core-shell nanosystems. The core-shell chemistries, synergistic effects, and interfacial heterojunctions in core-shell nanosystems enhance their stability, catalytic and physicochemical attributes, which possess high performance in cancer therapeutics. This review article summarizes research and development dedicated to engineering mesoporous core-shell nanosystems, especially silica nanoparticles and Fe3O4@Au nanoparticles, owing to their unique physicochemical characteristics. Moreover, it highlights state-of-the-art magnetic and optical attributes of Fe3O4@Au and MPSNP-based cancer therapy strategies. It details the designing of Fe3O4@Au and MPSN to bind with drugs, receptors, ligands, and destroy tumour cells and targeted drug delivery. This review serves as a fundamental comprehensive structure to guide future research towards prospects of core-shell nanosystems based on Fe3O4@Au and MPSNP for cancer theranostics.

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Hyaluronidase expression is known to be upregulated in various pathological conditions. A method based on a combination of ratiometric surface-enhanced Raman scattering (SERS) and magnetic separation is described for the determination of hyaluronidase (HAase) activity. Gold nanospheres (AuNPs) functionalized by 4-mercaptophenylboronic acid (4-MPBA) form stable cyclic esters with diol on hyaluronic acid (HA) by the boronic acid group, while Fe3O4@DTNB@Au modified with mercaptoethylamine (MEA) was used as a capture substrate to bind to the carboxyl group on the surface of HA, forming the "Au@4-MPBA@HA/Fe3O4@DTNB@Au@MEA" "core-satellite" structure. When HAase is present, HA is enzymatically disrupted, resulting in the destruction of the "core-satellite" structure, the SERS signal of 4-MPBA is subsequently weakened. The gold shell in the substrate protects the 5,5'-Dithio bis-(2-nitrobenzoic acid) (DTNB) from the external environment, which makes it become an ideal internal standard (IS) molecule for subsequent calibration. Under optimal conditions, the I1075/I1324 varied in the range of 10-3 - 10 U‧mL-1 HAase activity, with a limit of detection (LOD) of 0.32 mU‧mL-1，below the level of HAase in normal human body fluids. This method has been successfully applied to the determination of HAase activity in urine and is expected to provide a new method in disease detection, especially in the non-invasive detection of bladder cancer.

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A label-free electrochemical aptasensor based on magnetic α-Fe2O3/Fe3O4 heterogeneous hollow nanorods was developed for the detection of cancer antigen 125 (CA125). Magnetic α-Fe2O3/Fe3O4 heterogeneous hollow nanorods were successfully prepared by the hydrolysis-calcination method, functionalized with polyethyleneimine (PEI), and modified with HAuCl4 to form magnetic α-Fe2O3/Fe3O4-Au nanocomposites with a layer of 5 nm gold nanoparticles (Au NPs) on the surface. The magnetic α-Fe2O3/Fe3O4-Au nanocomposites were used to fix the DNA-aptamer probe to amplify the current signal. The intensity of the current signal was proportional to the concentration of CA125, indicating that the sensor was a turn-on sensor. The linear range of the electrochemical aptasensor was 5-125 U/mL (R2 = 0.9975), and the limit of detection (LOD) was 2.99 U/mL. The electrochemical aptasensor exhibited favorable specificity, reproducibility, and stability. The analytical performance of the aptasensor in real serum samples was also investigated.

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In this study, we developed a fluorescent aptasensor based on Fe3O4/Au/g-C3N4 and a FAM-labeled aptamer (FAM-SMZ1S) against sulfamethazine (SMZ) for the specific and sensitive detection of SMZ in food matrix. The FAM-SMZ1S was adsorbed by the Fe3O4/Au/g-C3N4 via π-π stacking and electrostatic adsorption, serving as a basis for the ultrasensitive detection of SMZ. Molecular dynamics was used to explain the reasons why SMZ1S and SMZ were combined. This aptasensor presented sensitive recognition performance, with a limit of detection of 0.16 ng/mL and a linear range of 1-100 ng/mL. The recovery rate ranged from 91.6% to 106.8%, and the coefficient of variation (CV) ranged from 2.8% to 13.4%. In addition, we tested the aptasensor for the monitoring of SMZ in various matrix samples, and the results were well-correlated (R2 ≥ 0.9153) with those obtained for HPLC detection. According to these results, the aptasensor was sensitive and accurate, representing a potentially useful tool for the detection of SMZ in food matrix.

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We report a method for fast Fourier transform (FFT)-weighted optical coherence tomography (OCT) in the second biological tissue transparency window by actively modulating the plasmonic scattering of Fe3O4@Au hybrid nanorods using magnetic fields. Instead of tracking the nanoparticles' lateral displacement in conventional magnetomotive OCT imaging, we monitor the nanorod rotation and optical signal changes under an alternating magnetic field in real time. The coherent rotation of the nanorods with the field produces periodic OCT signals, and the FFT is then used to convert the periodic OCT signals in the time domain to a single peak in the frequency domain. This allows automatic screening of nanorod signals from the random biological noises and reconstruction of FFT-weighted images using a computer program based on a time-sequence image set. Compared with conventional magnetomotive OCT, the FFT-weighted imaging technique creates enhanced OCT images with dB-scale contrast over an order of magnitude higher than the original images.

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The complex physiological environment and inherent self-healing function of tumors make it difficult to eliminate malignant tumors by single therapy. In order to enhance the efficacy of antitumor therapy, it is significant and challenging to realize multi-mode combination therapy by utilizing/improving the adverse factors of the tumor microenvironment (TME). In this study, a novel Fe3O4@Au/PPy nanoplatform loaded with a chemotherapy drug (DOX) and responsive to TME, near-infrared (NIR) laser and magnetic field was designed for the combination enhancement of eliminating the tumor. The Fe2+ released at the low pH in TME can react with endogenous H2O2 to induce toxic hydroxyl radicals (·OH) for chemodynamic therapy (CDT). At the same time, the generated Fe3+ could deplete overexpressed glutathione (GSH) at the tumor site to prevent reactive oxygen species (ROS) from being restored while producing Fe2+ for CDT. The designed Fe3O4@Au/PPy nanoplatform had high photothermal (PT) conversion efficiency and photodynamic therapy (PDT) performance under NIR light excitation, which can promote CDT efficiency and produce more toxic ROS. To maximize the cancer-killing efficiency, the nanoplatform can be successfully loaded with the chemotherapeutic drug DOX, which can be efficiently released under NIR excitation and induction of slight acidity at the tumor site. In addition, the nanoplatform also possessed high saturation magnetization (20 emu/g), indicating a potential magnetic targeting function. In vivo and in vitro results identified that the Fe3O4@Au/PPy-DOX nanoplatform had good biocompatibility and magnetic-targeted synergetic CDT/PDT/PTT/chemotherapy antitumor effects, which were much better than those of the corresponding mono/bi/tri-therapies. This work provides a new approach for designing intelligent TME-mediated nanoplatforms for synergistically enhancing tumor therapy.

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Photoacoustic (PA) imaging uses photon-phonon conversion for high-resolution tomography of biological tissues and functions. Exogenous contrast agents are often added to improve the image quality, but the interference from endogenous molecules diminishes the imaging sensitivity and specificity. We report a background-free PA imaging technique based on the active modulation of PA signals via magnetic alignment of Fe3O4@Au hybrid nanorods. Switching the field direction creates enhanced and deactivated PA imaging modalities, enabling a simple pixel subtraction to effectively minimize background noises. Under an alternating magnetic field, the nanorods exhibit PA signals of coherently periodic changes that can be converted into a sharp peak in a frequency domain via the fast Fourier transform. Automatic pixel-wise screening of nanorod signals performed using a computational algorithm across a time-sequence set of PA images regenerates a background-free PA image with significantly improved contrast, specificity, and fidelity.

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The combination of multiple therapeutic and diagnostic functions is fast becoming a key feature in the area of clinical oncology. The advent of nanotechnology promises multifunctional nanoplatforms with the potential to deliver multiple therapeutics while providing diagnostic information simultaneously. In this study, novel iron oxide-gold core-shell hybrid nanocomposites (Fe3O4@Au HNCs) coated with alginate hydrogel carrying doxorubicin (DOX) were constructed for targeted photo-chemotherapy and magnetic resonance imaging (MRI). The magnetic core enables the HNCs to be detected through MRI and targeted towards the tumor using an external magnetic field, a method known as magnetic drug targeting (MDT). The Au shell could respond to light in the near-infrared (NIR) region, generating a localized heating for photothermal therapy (PTT) of the tumor. The cytotoxicity assay showed that the treatment of CT26 colon cancer cells with the DOX-loaded HNCs followed by laser irradiation induced a significantly higher cell death as opposed to PTT and chemotherapy alone. The in vivo MRI study proved MDT to be an effective strategy for targeting the HNCs to the tumor, thereby enhancing their intratumoral concentration. The antitumor study revealed that the HNCs can successfully combine chemotherapy and PTT, resulting in superior therapeutic outcome. Moreover, the use of MDT following the injection of HNCs caused a more extensive tumor shrinkage as compared to non-targeted group. Therefore, the as-prepared HNCs could be a promising nanoplatform for image-guided targeted combination therapy of cancer.

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