Latex Microspheres Research Articles

Binary colloidal clusters with quantum dots for nanoscopic device applications

Colloidal clusters have garnered significant interest for their ability to elucidate nanoscopic phenomena in atomic arrangements and to enable the fabrication of complex nanostructures for advanced photonic and electronic applications. This study introduces a novel approach using binary colloidal clusters composed of semiconducting quantum dots and conductive gold-coated latex microspheres, fabricated via evaporation-driven self-assembly within emulsion droplets. This configuration not only demonstrates the binary colloidal clusters' capability for self-organization but also highlights the distinct regions formed by the smaller quantum dots, crucial for the electrical functionality of these nanoscopic devices. We have observed diode-like rectification behavior in these binary colloidal clusters, demonstrating their potential as active nanoscopic devices. Our findings present groundbreaking methodologies for integrating semiconductive and conductive materials in a colloidal form, offering a scalable and versatile platform for the development of next-generation devices in photonics and nanoelectronics.

Establishment of highly sensitive lateral flow immunochromatographic strips for quinclorac detection utilizing signal amplification nanoparticles

Highly selective herbicide quinclorac (Qui) is a type of quinoline carboxylic acid hormone herbicide, which has the characteristics of long half-life and difficulty for degradation, causing high risk to the environmental safety. In this study, anti-Qui 8A3 monoclonal antibody (mAb) with good specificity and high affinity (3.89 × 109 L/mol) was prepared, and two kinds of lateral flow immunochromatographic strips (LFICS) including nano-flower nanoparticles (AuNF) - and latex microsphere (LM)- based LFICS were established based on the antibody and signal amplification. The linear range of the AuNF- and LM- based LFICS were 5.31–345.48 ng/mL and 2.52–257.92 ng/mL, respectively. The limit of detection (LOD) of the AuNF- and LM- based LFICS were determined to be 5.31 ng/mL and 2.52 ng/mL, respectively. In summary, the developed LFICS using AuNF and LM as signal amplification reporters exhibited excellent sensitivity and provided the rapid on-site screening of Qui and other analytes in food safety field.

Sensitive dual-channel lateral flow immunoassay tagged with high brightness latex microsphere for simultaneous detection of respiratory viral antigens

Respiratory infectious diseases pose a serious threat to human health worldwide. Timely diagnosis is crucial for effective clinical management and infection control. Herein, we developed a dual-channel lateral flow immunoassay (DC-LFIA) for simultaneous sensitive detection of influenza A virus (IAV) and respiratory syncytial virus (RSV) nucleoprotein (NP) antigens. The high brightness latex microspheres (HB-LMs) exhibiting typical absorption peak at 540 nm with uniform size and excellent optical stability, were prepared by a simple surfactant-free emulsion polymerization by mixing Sudan red, which overcame the complexity and color instability met for traditional synthesis methods. After affinity evaluation, two antibody pairs have good affinity for IAV NP and RSV NP were separately identified. Then, combining antibody pairs as probes and HB-LMs as based signal tag, a DC-LFIA was constructed, by which the visual limit of detection is 25 pg/mL, 100 pg/mL for IAV NP and RSV NP, respectively, 10-fold more sensitive than gold nanoparticles based LFIA. The calculated limit of detection (S/N=3) of IAV NP and RSV NP was improved 22.8- and19.5-fold, respectively, in comparison with gold nanoparticles based LFIA. Additionally, the developed sensor shows excellent specificity and reproducibility. Furthermore, the as-proposed method was validated through the analysis of clinical samples, in good agreement with commercial colloidal gold kits. Thus, the developed DC-LFIA has great potential for clinical application in the multiplex detection of respiratory viral antigens.

A Highly Sensitive Lateral-Flow Strip Using Latex Microspheres to Detect NGAL in Urine Samples.

The incidence of kidney disease is increasing worldwide. Rapid and cost-effective approaches for early detection help prevent this disease. Neutrophil gelatinase-associated lipocalin protein (NGAL) is a novel biomarker for acute kidney injury (AKI) and chronic kidney disease (CKD). We aimed to develop a lateral flow strip (LFS) based on a lateral flow immunoassay method (LFIA), using latex microspheres (LMs) as a color labeling to detect NGAL in urine. The performance and potential of the developed LMs-LFS at a point-of-care (POC) testing were evaluated. The results showed that LMs-LFS successfully detected urinary NGAL within 15 min with high specificity without cross-reactivity to or interference from other endogenous substances in urine. The visual limit of detection (vLOD) was 18.75 ng/mL, and the limit of detection (LOD) was 1.65 ng/mL under the optimum condition. The LMs-LFS developed in this study showed a high correlation with the enzyme-linked immunosorbent assay (ELISA) method (R 2 = 0.973, n = 60 urine specimens) for detecting NGAL in urine. The LMs-LFS remained stable for at least six months at room temperature. The LMs-LFS can be a rapid, sensitive, and specific tool for the diagnosis and follow-up of renal disorders at the POC.

Active microparticle propulsion pervasively powered by asymmetric AC field electrophoresis

HypothesisSymmetry breaking in an electric field-driven active particle system can be induced by applying a spatially uniform, but temporally non-uniform, alternating current (AC) signal. Regardless of the type of particles exposed to sawtooth AC signals, the unevenly induced polarization of the ionic charge layer leads to a major electrohydrodynamic effect of active propulsion, termed Asymmetric Field Electrophoresis (AFEP). ExperimentsSuspensions containing latex microspheres of three sizes, as well as Janus and metal-coated particles were subjected to sawtooth AC signals of varying voltages, frequencies, and time asymmetries. Particle tracking via microscopy was used to analyze their motility as a function of the key parameters. FindingsThe particles exhibit field-colinear active propulsion, and the temporal reversal of the AC signal results in a reversal of their direction of motion. The experimental velocity data as a function of field strength, frequency, and signal asymmetry are supported by models of asymmetric ionic concentration-polarization. The direction of particle migration exhibits a size-dependent crossover in the low frequency domain. This enables new approaches for simple and efficient on-chip sorting. Combining AFEP with other AC motility mechanisms, such as induced-charge electrophoresis, allows multiaxial control of particle motion and could enable development of novel AC field-driven active microsystems.

Extending the use of normal hemispherical transmittance ([formula omitted]) measurements by modeling 3D multiple scattering radiative transfer

Spectrophotometers or optical benches using integrating spheres to measure normal-hemispherical transmittance TNH are widespread laboratory equipments. Although it is known that they cannot be used for ”highly turbid” samples, because multiple scattering may lead transmitted radiation to miss the entrance of the integrating sphere, very little is generally known about their exact validity range. Here we present a method to characterize the validity range of any such spectrophotometer and observe that most of them fail to measure TNH for scattering optical thickness above 0.25 (i.e. for TNH<0.9 in the case of non absorbing media with g=0). We also show how it is possible to continue using spectrophotometers even outside their TNH measurement validity range, without any calibration, thanks to a proper simulation of radiative transfer and geometrical optics. We make available the corresponding radiative transfer simulation tools as open access codes, that have been developed for a straightforward implementation on a wide range of experimental setups. The method is validated on three different spectrophotometers or optical benches using standardized latex microspheres, then its practical implementation is illustrated in the case of semi-conductor particles and photosynthetic microalgae. Errors in analysis arising from the misuse of such optical devices are discussed throughout the article.

Isolation of camel single domain antibodies against Yersinia pestis V270 antigen based on a semi-synthetic single domain antibody library and development of a VHH-based lateral flow assay.

Antibodies have been proven effective as diagnostic agents for detecting zoonotic diseases. The variable domain of camel heavy chain antibody (VHH), as an antibody derivative, may be used as an alternative for traditional antibodies in existing immunodiagnostic reagents for detecting rapidly spreading infectious diseases. To expedite the isolation of specific antibodies for diagnostic purposes, we constructed a semi-synthetic camel single domain antibody library based on the phage display technique platform (PDT) and verified the validity of this study. The semi-synthetic single domain antibody sequences consist of two parts: one is the FR1-FR3 region amplified by RT-PCR from healthy camel peripheral blood lymphocytes (PBLs), and the other part is the CDR3-FR4 region synthesised as an oligonucleotide containing CDR3 randomised region. The two parts were fused by overlapping PCR, resulting in the rearranged variabledomain of heavy-chain antibodies (VHHs). Y. pestis low-calcium response V protein (LcrV) is an optional biomarker to detect the Y. pestis infection. The semi-synthetic library herein was screened using recombinant (LcrV) as a target antigen. After four cycles of panning the library, four VHH binders targeting 1-270 aa residues of LcrV were isolated. The four VHH genes with unique sequences were recloned into an expression vector and expressed as VHH-hFc chimeric antibodies. The purified antibodies were identified and used to develop a lateral flow immunoassay (LFA) test strip using latex microspheres (LM) for the rapid and visual detection of Y. pestis infection. These data demonstrate the great potential of the semi-synthetic library for use in isolation of antigen-specific nanobodies and the isolated specific VHHs can be used in antigen-capture immunoassays.

Innovative application of Nile Red (NR)-based dye for direct detection of micro and nanoplastics (MNPs) in diverse aquatic environments

This paper presents the results of a research aimed at establishing a novel method for the detection of primary and secondary micro- and nanoplastics (MNPs), by using the fluorescence properties of the dye Nile Red-n-heptane (NR-H). The method has been applied to the detection of laboratory degraded polymers (Polystyrene, PS and Polyethylene Terephthalate, PET) as well as traceable latex microspheres in aqueous environments, showing a remarkable detection capacity and avoiding the prior extraction or processing of MNPs in natural samples, with significant time savings compared to conventional methods. The study has been carried out on various types of water, including samples from wastewater treatment plants, boreholes, seawater and synthesized seawater. The effectiveness of the staining process was evaluated by scanning electron microscopy (SEM), dynamic light scattering (DLS) and optical microscopy. As a result, a novel standardizable protocol for the rapid detection of MNPs has been established, with the potential to improve environmental protection through fast in-situ detection and identification of plastic contaminants. The limitations of the protocol in the quantification of MNPs have also been identified and further studies are proposed to overcome these limitations.

Imaging micrometer-sized aerosol particles with digital holography.

Small particles that are trapped, deposited, or otherwise fixed can be imaged by digital holography with a resolution approaching that of optical microscopy. When such particles are in motion as an aerosol, a comparable resolution is challenging to achieve. Using a simplified bi-telecentric lens system, we demonstrate that 1µm free-flowing aerosol particles can be imaged at the single-particle level using digital in-line holography. The imaging is demonstrated with an aerosol of 1µm polystyrene latex microspheres and a ragweed pollen aerosol.

Carbonation study of new calcium aluminate cement-based CO2 injection well sealants

In injection-well carbon storage projects, the degradation of Portland cement under harsh CO2 conditions is a primary concern. This study introduces novel CO2-resistant calcium aluminate cement (CAC) systems with addition of rubber latex and hollow glass microspheres which are added to the system to enhance the set cement resistance to CO2 corrosion and in the same time to optimize it for the application in a wide variety of well conditions. After exposure to near supercritical CO2 conditions (100 °C, 7 MPa) these systems exhibited enhanced compressive strength and reduced porosity compared with conventional Portland cement (PC) system, especially the one without latex. By subjecting degradation depth-resolved samples to thermogravimetry (TG) and X-ray diffraction (XRD) techniques, coupled with scanning electron microscopy (SEM), the study scrutinized alterations in microstructural properties. This methodological approach unveiled a profound grasp of carbonation mechanisms. Confirmed through TG and XRD analyses, the considerable reduction in carbonation establishes CAC as a compelling choice for CO2-resistant sealing within injection-well CO2 storage endeavors.

Development and characterization of a high-performance single-particle aerosol mass spectrometer (HP-SPAMS)

Abstract. This study describes a high-performance single-particle mass spectrometry (HP-SPAMS) design in detail. The comprehensive improvements in the injection system, optical sizing system, mass spectrometry, and data acquisition system have improved particle detection efficiency and chemical analysis. The combination of an aerodynamic particle concentrator (APC) system and a wide range of aerodynamic lenses (ADLs) enables the concentration of particles in the 100–5000 nm range. Using an APC increases the instrument inlet flow by a factor of 3–5. The ion delayed-exaction technology of bipolar time-of-flight mass spectrometry improves the mass resolution by 2–3 times, allowing the differentiation of isobaric ions of different substances. Moreover, the four-channel data acquisition technology greatly enhances the dynamic range of mass spectrometry. The improved HP-SPAMS enhances the overall capability of the instrument in terms of particle detection number and scattering efficiency. Moreover, it improves accuracy and sensitivity for component identification of individual particles. The experimental performance of HP-SPAMS shows that the scattering efficiency of polystyrene latex microspheres is almost 70 %–100 % in the range of 300–3000 nm. Compared to the previous SPAMS, HP-SPAMS has a larger inlet flow rate and scattering efficiency and a higher laser frequency, which makes HP-SPAMS increase the effective number of particles detected and improve the temporal resolution of detection. For the analysis of individual particles, HP-SPAMS achieves an average mass spectral resolution of 2500 at m/z 208, which helps distinguish between most organic fragment ions and metal ions and facilitates the analysis of complex aerosol particles. For the analysis of individual particles, the increased resolution of the HP-SPAMS contributes to the differentiation of most organic fragment ions and metal ions and facilitates the evaluation of complex aerosol particles, in the case of atmospheric lead-containing particles. The improved detection efficiency and chemical analysis capability of HP-SPAMS will be of great importance for low-concentration aerosol detection and complex aerosol component analysis.

Study on the subjective brightness of photonic crystal structural colored wood products

ABSTRACT Photonic crystal structural color is a novel method in the field of colored coating on the surface of wood products. However, the subjective brightness of photonic crystal structural colored wood products under different color temperature light sources has not been studied. In this study, poly(styrene-methyl methacrylate-acrylic acid) latex microspheres with different diameters were used to construct photonic crystal coatings on wood surface. The subjective brightness psychological quantity under different color temperature light sources was obtained. Combined with the optical properties of the coatings, the correlation between the physical optical properties of the photonic crystal coating, the color temperature of the light source and the subjective brightness of the coating was obtained. The photonic crystal coating in the near red visible light wavelength range had higher subjective brightness under low color temperature light source, and coating in the near purple visible light wavelength range had higher subjective brightness under high color temperature light source. The subjective brightness of the photonic crystal coating was very closely related to the light source color temperature and closely related to the reflectivity of the coating. This study expands the research on the optical properties of photonic crystal structure colored wood products.

Comparative analysis of three immunochromatographic test strips for rapid detection of cadmium ion in Asparagus

SummaryCurrently, there is increasing concern regarding the presence of cadmium ion (Cd2+) residues in Asparagus, necessitating the development of a rapid, sensitive and effective detection method. Immunochromatographic detection techniques offer a swift and efficient primary screening approach, significantly reducing labour and material resources compared to traditional detection methods. In this study, we aimed to construct and optimise an immunochromatographic test strip method for precise determination of Cd2+ content in Asparagus. To achieve this, monoclonal cadmium antibody (4A9) was prepared and conjugated with colloidal gold nanoparticles (AuNPs), latex microspheres (LM) and polydopamine (PDA) to create immunoprobes for test strip construction. We optimised key factors, such as probe parameters, strip assembly conditions and sample pretreatment methods. The sensitivity and detection capabilities of the three test strips were evaluated using actual Asparagus samples. The results demonstrated that all three immunochromatographic test strips exhibited high sensitivity, efficiency and rapidity in detecting Cd2+ levels in Asparagus. Notably, the LM‐based and PDA‐based test strips showed outstanding performance, with a visual limit of detection (vLOD) of 0.1 ng mL−1 and an elimination value of 2.0 ng mL−1. These findings underscore the promising potential of these test strips for practical cadmium detection in Asparagus samples.

Ultrarobust self-healing elastomers with hydrogen bonding connected MXene network for actuator applications

Self-healing ability is highly desired for flexible actuators that operate in dynamic and real-world environments, as these machines are vulnerable to mechanical damage. However, self-healing properties and mechanical strength are often difficult to combine at the same time. We report a synergistic enhancement strategy based on the ordered micro-nano structure and interfacial hydrogen bonding aggregation to achieve self-healing elastomer toughening. The hydrogen bonding interaction drives the MXene nanosheet to self-assemble into an interconnected network around the PU latex microsphere. Thanks to the synergy of dynamic physical networks and high-density interfacial hydrogen bonding, the composites with controllable room temperature self-healing efficiency (76.5–95.9%) and tensile strength (17.7–42.6 MPa). Furthermore, the MXene network structure of the composite endows the actuator with an efficient photothermal conversion efficiency, fast responsiveness, and even functional recovery. It is an effective strategy to achieve high-strength self-healing materials through hydrogen bonding connected MXene network and interfacial hydrogen bonding aggregation, which is expected to be applied to other flexible devices, such as flexible sensors and electromagnetic shielding.

Triplex-colored nucleic acid lateral flow strip and multiplex polymerase chain reaction coupled method for quantitative identification of beef, pork and chicken

Meat adulteration is one of the worldwide challenges for food quality control. Now, we developed a multiplex PCR and nucleic acid lateral flow strip (mPCR-NALFS) integrated method that employs triplex-color latex microspheres (LMs) as visual labels for simultaneous identification of beef, pork and chicken DNA. First, three primer pairs for beef, pork and chicken DNA are tailed with specific oligonucleotide sequences (anti-recognition/anti-detection/anti-control probes) as swing tags. Then, double-stranded amplicons obtained after mPCR amplification were flanked by tags. Finally, these amplicons can accurately hybridize with the pre-immobilized recognition probes on the conjugate pad, detection probes on the test lines and control probes on the control line, respectively. The LMs and recognition probe modified LMs were characterized by scanning electron microscopy, ultraviolet-visible spectroscopy and Fourier Transform Infrared spectroscopy. This strip can quantitatively detect beef, pork and chicken DNA within 10 min without compromising on accuracy compared to the electrophoresis. Specificity analysis revealed no cross-reactivity with meat derived from beef, pork, chicken, duck, mutton, rabbit, goose, ostrich, camel and horse meat. As low as 0.1 % (wt%) of beef, pork and chicken in the simulated adulterated meats were co-detected. This assay was successfully employed for adulteration identification in 28 commercial beef and lamb products.

Configurable vortex laser beams for optical manipulations of microparticle ensembles

The formation of phase holograms by the modulation superposition method for producing a set of vortex laser beams is presented. Produced vortex laser beams are considered to be used in the scheme of optical tweezers for optical trapping and manipulation of ensembles of latex microspheres. Applying the method of modulation superposition is regarded to synthesize phase holograms by adding harmonic functions with specific parameters. The possibility of independent control of the position of produced vortex beams and their orbital angular momentum is experimentally demonstrated, being in a good agreement with theoretical analysis. The use of structured light in combination with optothermal traps is likely to expand the traditional methods of microobject optical manipulation. The results obtained open up new possibilities for optical manipulation in biomedical applications.

An efficient and convenient Fiber -2- based latex agglutination test for the detection of antibodies against fowl adenovirus serotype 4 in clinical samples

To detect the antibody against fowl adenovirus serotype 4 (FAdV-4) in clinical practice, the latex agglutination test (LAT) was developed by using the Fiber-2 protein of FAdV-4 as an antigen bound to sensitized latex microspheres. The concentration, time, and temperature of sensitization latex microspheres by the Fiber-2 protein were studied and optimized; the specificity, sensitivity, and repeatability of LAT were tested; and the method developed in the study was applied. The results showed that the optimum sensitization concentration of Fiber-2 protein was 0.8 mg/mL, the time was 120 min, and the temperature was 37 ℃. Except for antiserum against FAdV-4 and FAdV-10, LAT developed in the study could not agglutinate antisera against FAdV-1, FAdV-2, FAdV-3, FAdV-4, FAdV-5, FAdV-6, FAdV-8a, FAdV-8b, FAdV-11, Newcastle disease virus, infectious bronchitis virus, egg drop syndrome virus and Clostridium perfringens. Compared with the commercial FAdV-4 ELISA Kit, the titers in 21 clinical samples were low when tested by the developed LAT method, but there was no significant difference. The coefficients of variation among different batches and the same batch of latex-sensitized particles were between 0 % and 13.3 % and 0–8.7 %, respectively. The critical value of immune protective antibody against FAdV-4 was 25, and the titers in 40.9 % of clinical samples were higher than the immune critical point. The results showed that the Fiber-2-based LAT developed in the study has the characteristics of high specificity, sensitivity and repeatability, has the advantages of free equipment, long shelf life, and fast and easy operation, and is an effective and convenient method for serological diagnosis of FAdV-4 infection and evaluating the efficacy of vaccines.

Sensitive and rapid detection of tetrodotoxin based on gold nanoflower-and latex microsphere-labeled monoclonal antibodies.

Tetrodotoxin (TTX) could result in serious diseases due to its extremely high neurotoxicity. Thus, it is of great importance to measure TTX for food safety. In this study, an anti-TTX monoclonal antibody with good specificity and high affinity was used to develop the immunochromatographic test strips (ICTS). Gold nanoflower (AuNF) with multiple branches and latex microsphere (LM) with large particle size as signal reporters were employed for improving the sensitivity of test strips. Both AuNF and LM probes are stable, and the developed ICTS were specific to TTX, demonstrating no cross-reactivity with other marine toxins. The linear range of AuNF- and LM-based strips for TTX was 9.49-330.98ng/mL and 5.40-443.19ng/mL, respectively. The limit of detection (LOD) of AuNF- and LM-based strips was determined to be 9.49ng/mL and 5.40ng/mL, respectively. In summary, the developed ICTS based on AuNF and LM signal probes displayed enhancement of sensitivity and provided rapid and specific detection of TTX.

Preparation, Identification and Preliminary Application of the Fenvalerate Monoclonal Antibody in Six Kinds of Dark Tea

Fenvalerate has the advantages of a broad insecticidal spectrum, high efficiency, low toxicity and low cost, and it is widely used in agriculture, especially in tea, resulting in the accumulation of fenvalerate residues in tea and the environment, posing a serious threat to human health. Therefore, the timely monitoring of fenvalerate residue dynamics is vital for ensuring the health of humans and the ecological environment, and it is necessary for establishing a fast, reliable, accurate and on-site method for detecting fenvalerate residues. Based on the methods of immunology, biochemistry and molecular biology, mammalian spleen cells, myeloma cells and mice were used as experimental materials to establish a rapid detection method of an enzyme-linked immunosorbent assay to detect the residues of fenvalerate in dark tea. Three cell lines-1B6, 2A11 and 5G2-that can stably secrete fenvalerate antibodies were obtained by McAb technology, and their sensitivities (IC50) were 36.6 ng/mL, 24.3 ng/mL and 21.7 ng/mL, respectively. The cross-reaction rates of the pyrethroid structural analogs were all below 0.6%. Six dark teas were used to detect the practical application of fenvalerate monoclonal antibodies. The sensitivity IC50 of the anti-fenvalerate McAb in PBS with 30% methanol is 29.12 ng/mL. Furthermore, a latex microsphere immunochromatographic test strip with an LOD of 10.0 ng/mL and an LDR of 18.9-357 ng/mL was preliminarily developed. A specific and sensitive monoclonal antibody for fenvalerate was successfully prepared and applied to detect fenvalerate in dark teas (Pu'er tea, Liupao tea, Fu Brick tea, Qingzhuan tea, Enshi dark tea and selenium-enriched Enshi dark tea). A latex microsphere immunochromatographic test strip was developed for the preparation of rapid detection test strips of fenvalerate.

Photoacoustic Flow Cytometry Using Functionalized Microspheres for Selective Detection of Bacteria.

Photoacoustic flow cytometry is a method to detect rare analytes in fluids. We developed photoacoustic flow cytometry to detect pathological cells in body fluids, such as circulating tumor cells or bacteria in blood. In order to induce specific optical absorption in bacteria, we use modified bacteriophage that precisely target bacterial species or subspecies for rapid identification. In order to reduce detection variability and to halt the lytic lifescycle that results in lysis of the bacteria, we attached dyed latex microspheres to the tail fibers of bacteriophage that retained the bacterial recognition binding sites. We tested these microsphere complexes using Salmonella enterica (Salmonella) and Escherichia coli (E. coli) bacteria and found robust and specific detection of targeted bacteria. In our work we used LT2, a strain of Salmonella, against K12, a strain of E. coli. Using Det7, a bacteriophage that binds to LT2 and not to K12, we detected an average of 109.3±9.0 of LT2 versus 2.0±1.7 of K12 using red microspheres and 86.7±13.2 of LT2 versus 0.3±0.6 of K12 using blue microspheres. These results confirmed our ability to selectively detect bacterial species using photoacoustic flow cytometry.