Search Results (138)

Aflatoxin B1 (AFB1), a highly carcinogenic mycotoxin, has been the focus of research for the development of efficient detection methods. In this study, a novel magnetic immuno-ratiometric fluorescent sensing system was constructed for the quantitative detection of AFB1. Green-emitting carbon quantum dots were conjugated with AFB1 monoclonal antibody to obtain GCDs@AFB1 mAb, and AFB1 oxime was immobilized on Fe₃O₄ magnetic microspheres to prepare AFB1-Ox@Fe₃O₄ NPs. After the immune-competitive adsorption of GCDs@AFB1 mAb by AFB1-Ox@Fe₃O₄ NPs and free AFB1, magnetic separation was performed. Red fluorescent silver nanoclusters were introduced as an internal reference to construct a GCDs-AgNCs ratiometric fluorescent system. The sensor exhibited a good linear response in the range of 0~240 pg/mL with a low limit of detection of 18 pg/mL and excellent selectivity. The spiked recoveries in real samples ranged from 92.14% to 110.02%, with a relative standard deviation of 0.57% to 4.58%. Combining the specific antigen–antibody recognition with magnetic separation technology, this method addresses the issues of poor stability and high environmental interference of traditional fluorescent sensors, and provides a new strategy for the sensitive and stable detection of AFB1. Full article

The treatment of full-thickness skin defects remains a major challenge in clinical medicine. Accelerating wound healing and promoting the restoration of tissue function are of paramount importance. Stem cell therapy has been applied in clinical practice to facilitate wound repair. However, the low survival rate of transplanted stem cells in an ischemic and hypoxic microenvironment severely limits the effectiveness of their clinical application. Microspheres, owing to their excellent biocompatibility and drug delivery capabilities, can serve as effective carriers for oxygen transport. It is worthwhile to evaluate the timing and process of oxygen release under hypoxic conditions. In this study, core–shell structured oxygen-releasing microspheres were prepared and incorporated with the photosensitizer hypericin (HYP) to enable dynamic tracking of the oxygen release process via fluorescent signals. The effects of the oxygen-releasing microspheres on cells under hypoxic conditions were analyzed, focusing primarily on the characterization of the microspheres, their biocompatibility, luminescent properties, and oxygen-releasing capacity. Furthermore, the efficacy of the oxygen-releasing microspheres in combination with bone marrow mesenchymal stem cells (BMSCs) in promoting wound healing was evaluated in vivo. The results indicate that the addition of the microspheres improved cell survival rates in hypoxic environments; meanwhile, their luminescent properties demonstrated the potential of fluorescence intensity as a visual indicator of oxygen release. Full article

In the fields of cell engineering, bio-fabrication, and targeted therapy, achieving high-precision manipulation of microparticles and cells remains a technical challenge. Although acoustic tweezers based on surface acoustic waves (SAWs) offer a promising solution, the structural complexity of conventional SAW devices has limited their practical applications. This work proposes a symmetric interdigitated transducer (IDT)-based acoustic tweezers device featuring a simple structure and high flexibility for modulating acoustic pressure field patterns and enabling particle manipulation. Theoretical investigations into the particle manipulation mechanism of the proposed device were conducted using the finite element method. A detachable polymethyl methacrylate (PMMA) assembly chamber was also designed. The effectiveness of the device was validated through dynamic and reconfigurable manipulation experiments using fluorescent polystyrene microspheres. Experimental results demonstrate that the proposed device can rapidly and precisely modulate SAW to achieve array-based manipulation of particle clusters, forming corresponding array patterns. Compared with conventional sorting methods, this device offers advantages including low cost, high precision, ease of operation, and good biocompatibility, making it suitable for large-scale manipulation of microparticles and biological cells. This technology has the potential to expand the application landscape of SAW and may emerge as a cutting-edge approach for directed cell assembly and culture. Full article

Rare-earth-doped microsphere cavities have attracted significant interest for applications in miniaturized photonic devices due to their unique optical properties. In this work, Yb³⁺/Er³⁺ co-doped microsphere cavities were fabricated via a melting method, which enables uniform interior doping at high and tunable rare-earth concentrations through a simpler and more cost-effective process compared with existing coating and fiber-etching approaches. Whispering gallery modes (WGMs) enhanced upconversion luminescence, which was observed using tapered fiber coupling, producing a vivid green fluorescence ring near the equatorial region of the microsphere. The luminescence characteristics of the microsphere cavity were investigated by measuring the fluorescence spectra under varying excitation powers. The results indicated that the fluorescence emission follows a two-photon absorption process, consistent with the upconversion emission mechanism of Er³⁺. A finite difference time domain (FDTD) model was employed to simulate the optical field distribution within the microsphere cavity. At a microsphere diameter of 90 μm and a coupling gap of 0 μm, both the 980 nm pump light and the emitted light were effectively confined near the equatorial region of the microsphere, forming WGM confinement patterns. These findings are expected to advance the application of rare-earth-doped microsphere cavities in fields such as biosensing, bioimaging, optical communications, and upconversion microlasers. Full article

Brucellosis, a zoonotic disease caused by Brucella, requires rapid, accurate, and sensitive diagnostic methods for effective prevention and control. This study presents the development of a fluorescence microsphere immunochromatographic assay (QDMs-ICA) for detecting anti-Brucella antibodies in bovine serum and milk. Lipopolysaccharide (LPS) from the Brucella abortus strain A19 was immobilized on the nitrocellulose membrane (NC membrane) as the test line (T-line), while rabbit anti-SPG polyclonal antibody was applied as the control line (C-line). Recombinant streptococcal protein G conjugated with quantum dot microspheres (QDMs-SPG) served as the detection conjugate. After optimizing the preparation parameters of QDMs-ICA, the method demonstrated sensitivities of approximately 0.98 IU/mL for bovine serum and 1.56 IU/mL for milk. No cross-reactions were observed with antibody-positive sera from Coxiella burnetii, Mycobacterium avium paratuberculosis, Mycobacterium tuberculosis, Chlamydia abortus, Bacillus anthracis, Escherichia coli O157:H7, Vibrio cholerae or Salmonella, indicating excellent specificity. In intra- and inter-batch repeatability tests, the coefficient of variation (CV) remained below 15%, confirming good reproducibility. The detection limit remained stable after storage at 37 °C for 7 days. Parallel testing of 150 bovine serum samples and 80 milk samples showed a high degree of concordance with the ID-VET commercial kit, with coincidence rates of 97.3% and 96.3%, respectively. These results demonstrate that QDMs-ICA offers high specificity, sensitivity, repeatability, and reliability, making it an effective tool for the rapid detection and epidemiological monitoring of brucellosis. Full article

The development of high-throughput, sensitive and portable strategies for detecting foodborne pathogens is urgently needed in food safety, especially during an outbreak. Herein, an ultrasensitive suspension array was constructed by designing photonic crystal microsphere (PCM)-assisted loop-mediated isothermal amplification (LAMP) for Staphylococcus aureus detection. The PCM-LAMP suspension array integrated the optical signal enhancement capability of the biomimetic microporous three-dimensional PCM surface with the thousand-fold signal amplification of LAMP. The biomimetic PCMs displayed a periodic dielectric nanostructure and enhanced the fluorescence intensity of the LAMP reaction, leading to high sensitivity. The PCM-LAMP suspension array allowed sensitive detection of the target DNA of S. aureus without long-term culture. Under optimal conditions, the limit of detection for S. aureus genomic DNA reached as low as 0.18 fM, and the assay exhibited excellent specificity against other bacteria. Furthermore, trace target DNA in food samples was accurately quantified, demonstrating its potential for practical applications. Therefore, the developed PCM-LAMP suspension array holds great promise for ultrasensitive and rapid detection of foodborne pathogens. Full article

Serial flow cytometry was recently introduced as a method that can estimate measurement uncertainty (i.e., imprecision, the coefficient of variation of repeated measurements of individual particles) independent from population characteristics. Replication of light sources and detectors at multiple sites along a flow cytometer’s microchannel requires more equipment and can complicate detector synchronization. Here, we introduce amplitude modulation to encode each region of a serial cytometer with a unique carrier frequency, which enables demultiplexing of the combined signal incident on a single photodetector by fast Fourier transform (FFT) peak magnitude. To facilitate validation of detection, matching, and uncertainty quantification of fluorescence signals, we designed a microfluidic amplitude modulation (AM) serial flow cytometer that has ground truth detectors on individual regions (serial cytometry) in parallel with the combined channel detection for AM demultiplexing. With this report, we present metrics for event detection and dynamic range, prevalence and processing of overlapping detections, region-decoding accuracy, process yield, and uncertainty quantification on a brightness ladder of calibration microspheres. Despite being operated with reduced light intensities, the AM cytometer was capable of high-fidelity performance in comparison to conventional serial cytometry. For events above the detection limit, over 97% were analyzed. Both conventional and AM serial cytometers achieved median imprecisions in the range of 0.53% to 2.1% after outlier removal, which was well below the inherent intensity distribution of any of the microsphere subpopulations. Overall, AM cytometry supports uncertainty quantification and temporal analyses of serial cytometry data with a reduced number of photodetectors, which offers simplification of chip design with multiple measurement regions and wide-field detectors. Full article

Hydrogel fluorescent microspheres function as versatile tracers with applications spanning across biomedicine, complex plasma systems, hydrodynamics, and drug delivery. However, the controlled release of fluorescent material in hydrogel microspheres is challenging to achieve. The fluorescent hydrogel microsphere (namely poly(ethylene glycol) diacrylate@rhodamine B-tannic acid, PEGDA@RhB-TA) was fabricated by incorporating tannic acid and RhB into PEGDA microspheres. The stable encapsulation and responsive release of RhB can be achieved by leveraging the non-covalent interactions between TA and RhB. RhB was stably encapsulated within PEGDA microspheres through noncovalent interactions (hydrophobic interactions, hydrogen bonding, π–π, and ion–π interactions) between RhB and TA. Both molecular dynamics simulations by GROMACS and experimental results confirmed the noncovalent binding mechanisms between RhB and TA. The microspheres retained RhB following 24 h immersion in a highly concentrated salt solution (1 M NaCl) and exhibited minimal RhB release (7.1%) under heating at 80 °C for 24 h. However, PEGDA@RhB-TA microspheres underwent rapid RhB release in a 50% v/v ethanol–water solution, liberating 73% of the encapsulated dye within 24 h. TA within the PEGDA@RhB-TA microsphere acts as a molecular lock by forming non-covalent interactions with RhB, significantly enhancing the stability of encapsulated RhB, and enabling the responsive release of RhB under specific conditions. Upon introduction into a microfluidic chip, PEGDA@RhB-TA microspheres enable the calculation of flow velocity through position tracking using high-speed camera imaging and fluorescence microscopy. These microspheres overcome the dual challenges of tracer stability and controlled release, making them suitable for fluid tracing and measuring flow rates. Full article

This paper provides a systematic review of the progress in encoded microsphere suspension array technology and its application in the multiplex detection of mycotoxins. Mycotoxins are diverse and frequently coexist in food matrices, leading to synergistic toxic effects. This poses significant challenges to existing risk assessment systems. Current multiplex detection methods still face technical bottlenecks such as target loss, matrix interference, and reliance on large-scale instruments. Suspension array technology based on encoded microspheres, combined with efficient signal amplification strategies, offers an ideal platform for achieving highly sensitive and high-throughput analysis of mycotoxins. This paper systematically reviews the core aspects of this technology, including encoding strategies such as physical, optical, and multi-dimensional approaches, along with new encoding materials like aggregation-induced emission materials and fluorescent proteins. It further covers matrix materials and preparation methods with an emphasis on green, biocompatible options and integrated fabrication techniques, as well as signal amplification mechanisms based on nucleic acid amplification, enzyme catalysis, and nanomaterials. The integration of magnetic separation techniques and the combination with portable, smartphone-based platforms for intelligent on-site detection are also highlighted. Finally, this review outlines future development trends such as the incorporation of artificial intelligence, 3D printing, and smart algorithms, aiming to provide theoretical references and technical support for research and applications in related fields. Full article

Aflatoxin B₁ (AFB₁), a highly toxic and carcinogenic mycotoxin, poses significant public health risks due to its widespread contamination of staple food crops such as peanuts and maize. Although conventional lateral flow immunoassays (LFIAs) are widely employed for rapid on-site screening, their limited sensitivity frequently compromises accurate quantification at trace levels. To improve the analytical performance of LFIAs, we developed a novel time-resolved fluorescence-based lateral flow immunoassay (TRFN-LFIA) by integrating reverse artificial antigen labeling with time-resolved fluorescence signal amplification. This method enhances detection sensitivity and enables rapid, ultra-sensitive, visible, and quantitative determination of AFB₁ in peanut and maize samples. Under optimized conditions, the TRFN-LFIA achieved a visible limit of detection (vLOD) of 0.30 ng/mL (2.22 µg/kg), a quantitative limit of detection (qLOD) of 0.04 ng/mL (0.30 μg/kg), and a half-maximal inhibitory concentration (IC₅₀) of 0.09 ng/mL. Recoveries from spiked peanut and maize samples ranged from 81.33% to 117.86%, with coefficients of variation (CVs) below 13.04%. Analysis of 21 real samples (13 maize and 8 peanut samples) yielded results highly consistent with those obtained by liquid chromatography–tandem mass spectrometry (LC-MS/MS). Moreover, the method demonstrates significant advantages in terms of detection speed, cost-effectiveness, and operational convenience. Therefore, the results established the TRFN-LFIA method as a reliable and practical tool for on-site rapid detection of AFB₁ in contaminated food matrices, providing both a rapid and accurate approach for trace-level quantification and a novel strategy for enhancing the sensitivity of lateral flow immunoassays. Full article

Microplastics (MPs) are synthetic environmental pollutants increasingly linked to adverse human health effects. To study their biological impact, researchers require access to environmentally relevant MPs that can be accurately tracked in biological systems. However, most ambient MPs are composed of non-conjugated polymers that lack intrinsic fluorescence, limiting their utility in live-cell or in vivo imaging. Addressing this challenge, we present two alternative labeling approaches that enable visualization, tracking, and quantification of MPs. First, we stained nylon and polypropylene MPs with Rhodamine 6G, a fluorescent dye known for its stability and compatibility with in vivo applications. These labeled MPs retained strong fluorescence in murine lung tissue for up to one week, as confirmed by fluorescent microscopy. Second, we conjugated aminated polystyrene microspheres with IRDye-800CW, a near-infrared fluorophore that enables high-resolution imaging with minimal tissue autofluorescence via an In Vivo Imaging System and confocal microscopy. In vivo experiments revealed organ-specific accumulation of IRDye-labeled MPs, with a 2.8-fold increase in the liver and a 5-fold increase in spleen compared to controls, detectable up to 72 h post-injection. These labeling strategies provide researchers with practical tools to visualize and study the biodistribution of MPs in biological systems, advancing efforts to understand their health implications. Full article

Capsaicinoids (CPCs) are regarded as a typical marker of waste oil, which has emerged as a serious food safety issue in developing countries, necessitating the development of rapid, sensitive, and specific detection methods. In this study, a novel hapten was synthesized to generate a high-affinity monoclonal antibody (mAb) targeting CPCs. Subsequently, aggregation-induced emission fluorescent microspheres (AIEFMs), known for their superior fluorescence intensity, were utilized as an enhanced probe to develop a lateral flow immunoassay (LFIA) based on mAb 8B4 for CPC detection. For comparison, a traditional gold nanoparticle (AuNP)-LFIA was also constructed using the corresponding mAb. The AIEFM-LFIA demonstrated a limit of detection (LOD) of 0.33 µg/kg for CPCs in edible oil samples, which is 4.21 times lower than the LOD of 1.39 µg/kg achieved by the AuNP-LFIA. And the assay effectively identified three additional CPCs, with LODs ranging from 0.26 to 0.99 µg/kg, while exhibiting minimal cross-reactivity with CPC analogs, indicating high specificity. The recovery rates of the AIEFM-LFIA in oil samples ranged from 75.0% to 106.0%, with coefficients of variation ≤ 8.3%, exhibiting excellent accuracy and precision. Furthermore, the results of the AIEFM-LFIA demonstrated a strong degree of correlation with liquid chromatography–tandem mass spectrometry, with a correlation coefficient (R²) of 0.978. Consequently, the developed AIEFM-LFIA shows significant promise as a rapid, sensitive, specific, and reliable method for detecting CPCs in oil samples. Full article

Microplastics (MPs) are widespread contaminants in seabeds, where they are bioavailable to benthic organisms including polychaetes. Among them, the bearded fireworm represents a potential target for MP, given its opportunistic predatory and scavenging habits, reaching high densities and displaying a wide expansion range in the Mediterranean Sea. In this pilot bench-scale study, we investigated MP ingestion and egestion in this species through a simplified two-level trophic chain, using mussels as prey. Mediterranean mussels were first exposed to fluorescently labelled polystyrene microspheres (micro-PS, nominal size of 10 µm) and offered to fireworms. Within three days, fireworm faecal pellets, intestines, and body fluids were collected and digested to quantify MP. In-depth microscopy analyses were carried out to evaluate potential chemical and physical alterations of MPs during gut passage. Minimal retention of MPs in fireworm tissues was observed, while faecal pellets contained substantial quantities of micro-PS. Despite most MPs exhibiting negligible chemical changes, they were covered by faecal matter and colonised by bacteria, with minor surface alterations. Our findings provide the first evidence of MP trophic transfer from a filter feeder to a carnivorous polychaete. The rapid excretion of MPs by bearded fireworms gives insights into polychaete-mediated MP fluxes and MP fate in benthic ecosystems. Full article

Circulating tumor cells (CTCs) are crucial biomarkers for lung cancer metastasis and recurrence, garnering significant clinical attention. Despite this, efficient and cost-effective detection methods remain scarce. Consequently, there is an urgent demand for the development of highly sensitive CTC detection technologies to enhance lung cancer diagnosis and treatment. This study utilized microspheres and A549 cells to model CTCs, assessing the impact of acoustic field forces on cell viability and proliferation and confirming capture efficiency. Subsequently, CTCs from the peripheral blood of patients with lung cancer were captured and identified using fluorescence in situ hybridization, and the results were compared to the immunomagnetic bead method to evaluate the differences between the techniques. Finally, epidermal growth factor receptor (EGFR) mutation analysis was conducted on CTC-positive samples. The findings showed that acoustic microfluidic technology effectively captures microspheres, A549 cells, and CTCs without compromising cell viability or proliferation. Moreover, EGFR mutation analysis successfully identified mutation types in four samples, establishing a basis for personalized targeted therapy. In conclusion, acoustic microfluidic technology preserves cell viability while efficiently capturing CTCs. When integrated with EGFR mutation analysis, it provides robust support for the precise diagnosis and treatment of lung cancer as well as personalized drug therapy. Full article

Structured illumination microscopy (SIM) with π/2 phase-shift modulation traditionally relies on frequency-domain computation, which greatly limits processing efficiency. In addition, the illumination regime inherent in structured illumination techniques often results in poor visual quality of reconstructed images. To address these dual challenges, this study introduces DM-SIM-LLIE (Differential Low-Light Image Enhancement SIM), a novel framework that integrates two synergistic innovations. First, the study pioneers a spatial-domain computational paradigm for π/2 phase-shift SIM reconstruction. Through system differentiation, mathematical derivation, and algorithm simplification, an optimized spatial-domain model is established. Second, an adaptive local overexposure correction strategy is developed, combined with a zero-shot learning deep learning algorithm, RUAS, to enhance the image quality of structured light reconstructed images. Experimental validation using specimens such as fluorescent microspheres and bovine pulmonary artery endothelial cells demonstrates the advantages of this approach: compared with traditional frequency-domain methods, the reconstruction speed is accelerated by five times while maintaining equivalent lateral resolution and excellent axial resolution. The image quality of the low-light enhancement algorithm after local overexposure correction is superior to existing methods. These advances significantly increase the application potential of SIM technology in time-sensitive biomedical imaging scenarios that require high spatiotemporal resolution. Full article