Formation of cagelike sulfonated polystyrene microspheres via swelling-osmosis process and loading of CdS nanoparticles

Synthesis of eco-friendly multifunctional dextran microbeads for multiplexed assays

There has been an increasing demand for simultaneous detection of multiple analytes in one sample. Microbead-based platforms have been developed for multiplexed assays. However, most of the microbeads are made of non-biodegradable synthetic polymers, leading to environmental and human health concerns. In this study, we developed an environmentally friendly dextran microbeads as a new type of multi-analyte assay platform. Biodegradable dextran was utilized as the primary material. Highly uniform magnetic dextran microspheres were successfully synthesized using the Shirasu porous glass (SPG) membrane emulsification technique. To enhance the amount of surface functional groups for ligand conjugation, we coated the dextran microbeads with a layer of dendrimers via a simple electrostatic adsorption process. Subsequently, a unique and efficient click chemistry coupling technique was developed for the fluorescence encoding of the microspheres, enabling multiplexed detection. The dextran microbeads were tested for 3-plex cytokine analysis, and exhibited excellent biocompatibility, stable coding signals, low background noise and high sensitivity.

CdSe/ZnS quantum dot-encoded maleic anhydride-grafted PLA microspheres prepared through membrane emulsification for multiplexed immunoassays of tumor markers

Early diagnosis of tumor markers is of great importance for the successful treatment of cancer. As a high-throughput and high-sensitivity detection technology, liquid suspension biochips based on quantum dot (QD) encoded microspheres have been widely used in the immunodetection of tumor markers. In this work, maleic anhydride grafted PLA (PLA-MA) microspheres based on quantum dot encoding were used as carriers for liquid phase suspension biochips for the immunoassay of tumor markers. PLA-MA fluorescent beads are prepared by embedding CdSe/ZnS quantum dots in PLA-MA using Shirasu porous glass (SPG) membrane emulsification technology, which has high fluorescence intensity, good stability, and good dispersion. Fluorescent immunoassays on dipsticks found that PLA-MA microspheres have high biological activity and good stability, which is conducive to immunoassays. Based on this, using the characteristics of CdSe/ZnS quantum dots and flow cytometry, monochromatic and two-color coding methods were developed, and 9 distinguishable coding beads were prepared. The results showed that PLA-MA fluorescent microspheres exhibited good biocompatibility, stable coding signals, low background noise, and low detection limits when performing quaternary immunoassays on tumor markers CA125, CA199, CA724, and CEA by CdSe/ZnS QD-encoded PLA-MA microsphere binding flow cytometry.

Phototropic Aggregation and Light-Guided Long-Distance Collective Transport of Colloidal Particles

Phoretic swarming and collective transport of colloidal particles in response to environmental stimuli have attracted tremendous interest in a variety of fields. In this work, we investigate the light-actuated motion, aggregation, and light-guided long-distance mass transport of silica microspheres in simple spiropyran solutions under the illumination of UV spot sources. The phototactic motion is confirmed by the dependence of swarming on the illumination intensity and spiropyran concentrations, ON-OFF switching tests, pattern-masked UV sources, etc. The aggregates formed via swarming of silica spheres can chase after a moving UV source, however, relying on a critical speed of the UV source. Only when the UV source speed is below the critical value, the aggregates follow the UV spot at a constant relative speed to the light spot. Analysis on the shape of silica microsphere currents indicates that continuous illumination of the UV spot source and resultant chemical gradients are important for the formation of steady microsphere currents. Light-guided aggregation and long-distance mass transport are interesting for targeted delivery and remote-controlled enrichment of environmental hazards.

Polymethacrylate Sphere-Based Assay for Ultrasensitive miRNA Detection

Although microRNAs (miRNAs) have emerged as increasingly important target analytes, their biorecognition remains challenging due to their small size, high sequence homology, and low abundance in clinical samples. Nanospheres and microspheres have also gained increasing attention in biosensor applications due to their high specific surface area and the wide variety of compositions available. In this study, chemically designed and synthesized microspheres with active functional groups were used to promote effective miRNA immobilization resulting in better biorecognition. Upon conjugation with fluorescence-labeled complimentary probes, acylate-based spheres have indirectly detected MiR159, offering significantly enhanced analytical sensitivity, specificity, and accuracy while yielding a considerably low limit of detection (LOD) of 40 picomolar. Furthermore, MiR159 presence, which is known to be inversely correlated to breast cancer incidence and progression, was successfully detected in a competitive assay, which is promising for upgrading the current assay to clinical use.

Pristine Graphene Microspheres by the Spreading and Trapping of Graphene at an Interface

The interfacial spreading and exfoliation of graphene was used to create low-density, hollow microspheres defined by a thin shell of graphene. The spheres were templated by a thermodynamically driven self-assembly process in which graphite spontaneously exfoliated and spread at the high-energy interfaces of a water-in-oil emulsion. Graphene thus acted as a 2D surfactant to stabilize the dispersed water droplets utilized as polymerization templates. Using a mixture of organic solvent and monomer as the emulsion oil phase, polystyrene-coated hollow graphene microspheres were created. These spheres were characterized by optical and electron microscopy, thermo-gravimetric analysis, nanoindentation, and particle sizing. The mechanism leading to the microsphere surface morphology and shape is discussed, with the oil phase composition shown to play a critical role.

Construction of polyporous polymer microspheres with a tailored mesoporous wall

Polymer microspheres with a novel hierarchically porous structure (inner macropores and a mesoporous wall) were fabricated by taking advantage of γ-ray-radiation-initiated dispersion polymerization.

One-step synthesis of silicon carbide foams supported hierarchical porous sludge-derived activated carbon as efficient odor gas adsorbent

Hierarchical porous sludge-derived activated carbon coated on macroporous silicon carbide (SiC) foams substrate has been facilely fabricated via a simple one-step strategy by utilizing sludge as carbon source, and jointly using zinc chloride and hexadecanol as pore forming agents. The sludge-derived carbon has been confirmed to be hierarchical macro-meso-microporous structure based on detailed characterization by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectra and nitrogen adsorption-desorption measurement. The adsorption tests showed that the hierarchical porous sludge-derived activated carbon fabricated by one-step pore-forming (zinc chloride and hexadecanol microemulsion mixture) possesses excellent adsorption capacity (259.9mgg^-1, breakthrough time reach 90min and saturation end-time up to 140min) of methyl mercaptan (CH₃SH). The excellent adsorption performance can be attributed to the macroporous SiC foam skeleton and the mesopores channel formed by nonionic surfactant hexadecanol micelles, as well as the micropores activated by ZnCl₂ as odor capture sites. The proposed pore-forming strategy paves an avenue for the sludge disposal and even the development of bio-derived materials.

One-Step Synthesis of Hollow Dimpled Polystyrene Microparticles by Dispersion Polymerization

The design and preparation of hollow nonspherical microparticles are of great significance for their potential applications, but the development of a facile synthetic method using only one production step remains a great challenge. In the current work, a new template-free method based on dispersion polymerization was successfully developed to produce anisotropic hollow polystyrene (PS) microparticles in a single step. In the synthesis, ammonium persulfate (APS) played a critical role in the formation and growth of highly uniform and stable hollow PS microparticles. By varying the concentration of APS and that of the stabilizer used, polyvinylpyrrolidone, we were able to control the average size of the PS particles and their degree of concavity. Based on our results and observations, a plausible mechanism for formation of these unusually shaped PS microparticles was proposed.

One-pot synthesis of porous Au-nanoparticles@polymer/reduced graphene oxide composite microspheres by γ-ray radiation and their application as a recyclable high-performance catalyst

Au-nanoparticles-embedded porous polymer/reduced graphene oxide composite microspheres, with ultra-high catalytic efficiency and recyclability, were fabricated through γ-ray in one pot.

Microsphere integrated microfluidic disk: synergy of two techniques for rapid and ultrasensitive dengue detection

The application of microfluidic devices in diagnostic systems is well-established in contemporary research. Large specific surface area of microspheres, on the other hand, has secured an important position for their use in bioanalytical assays. Herein, we report a combination of microspheres and microfluidic disk in a unique hybrid platform for highly sensitive and selective detection of dengue virus. Surface engineered polymethacrylate microspheres with carefully designed functional groups facilitate biorecognition in a multitude manner. In order to maximize the utility of the microspheres' specific surface area in biomolecular interaction, the microfluidic disk was equipped with a micromixing system. The mixing mechanism (microballoon mixing) enhances the number of molecular encounters between spheres and target analyte by accessing the entire sample volume more effectively, which subsequently results in signal amplification. Significant reduction of incubation time along with considerable lower detection limits were the prime motivations for the integration of microspheres inside the microfluidic disk. Lengthy incubations of routine analytical assays were reduced from 2 hours to 5 minutes while developed system successfully detected a few units of dengue virus. Obtained results make this hybrid microsphere-microfluidic approach to dengue detection a promising avenue for early detection of this fatal illness.

pH-Responsive cagelike porous polymer microspheres prepared via consecutive RAFT polymerization induced by γ-ray radiation

Poly(acrylic acid)-grafted cagelike polymeric microspheres with distinct pH-responsive release properties were fabricated through a two-step consecutive radiation induced RAFT polymerization.