Protein valves formed through click-reaction grafting of poly(N-isopropylacrylamide) onto electrospun poly(2,6-dimethyl-1,4-phenylene oxide) fibrous membranes

Performance Enhancement of Electrochemiluminescence with the Immunosensor Controlled Using Magnetized Masks for the Determination of Epithelial Cancer Biomarker EpCAM

The performance of an electrochemiluminescence (ECL) immunosensor was improved with a particle gradient. SiO₂-coated magnetic beads were adopted as nanocarriers for gradient manipulation and immobilized with the primary antibody. Cadmium telluride quantum dots were coated with a layer of protein G for conjugation and orientation of the secondary antibody as signal labels. ECL immunosensor gradients on the electrode were formed by magnetolithography (ML) with magnetized nickel masks of column and stripe arrays. The immunosensor generally aggregated as an island on the substrate, leading to a decrease of efficiency in the characteristic signals. Stripe arrays of magnetized nickel were designed to generate cylindrical magnetic flux on the substrate to improve the particle manipulation with the gradient. Various gradients of the sandwich-structured immunosensor substantially affected the electrochemical performance. Compared to the gradient-free immunosensor, the gradient of the immunosensor generated by ML using a 3 μm stripe array mask enhanced the ECL intensity ∼2.2 times. The results of quantification of epithelial cell adhesion molecules (EpCAM) with the gradient immunosensor showed a broad linear range (15-420 pg mL^-1), a low limit of detection (5.5 pg mL^-1), and high reliability for EpCAM-spiked serum samples, indicating that the immunosensor gradient substantially enhances the performance of the ECL assay.

Remote Performance Modulation of Ultrafiltration Membranes by Magnetically and Thermally Responsive Polymer Chains

Ultrafiltration membranes, that respond to an external magnetic field and local temperature have been developed. Surface-initiated activator-generated electron transfer (AGET) atom transfer radical polymerization (ATRP) has been used to graft poly(N-isopropylacrylamide) (PNIPAm) from the surface of 300 kDa regenerated cellulose membranes. The polymerization initiator was selectively attached to the entire membrane surface, only the outer membrane surface or only the inner pore surface. A superparamagnetic nanoparticle was attached to the end of the polymer chain. The DI water flux as well as the flux and rejection of bovine serum albumin were investigated in the absence and presence of a 20 and 1000 Hz oscillating magnetic field. In an oscillating magnetic field, the tethered superparamagnetic nanoparticles can cause movement of the PNIPAm chains or induce heating. A 20 Hz magnetic field maximizes movement of the chains. A 1000 Hz magnetic field leads to greater induced heating. PNIPAm displays a lower critical solution temperature at 32 °C. Heating leads to collapse of the PNIPAm chains above their Lower Critical Solution Temperature (LCST). This work highlights the versatility of selectively grafting polymer chains containing a superparamagnetic nanoparticle from specific membrane locations. Depending on the frequency of the oscillating external magnetic field, membrane properties may be tuned.

Hierarchically Structured All-biomass Air Filters with High Filtration Efficiency and Low Air Pressure Drop Based on Pickering Emulsion

Although a high-efficiency air filter can be achieved from electrospun nanofabrics, it has been challenging to reduce the pressure drop, increase the filtration capacity, and improve the production rate of the electrospinning process. Here, we report a hierarchically structured all-biomass air filter with high filtration efficiency and low air pressure drop based on applying Pickering emulsions to generate protein-functionalized nanostructures. Specifically, the air filter consists of cellulose nanofibers (CNF)/zein nanoparticles as active fillers prepared from Pickering emulsions and porous structures of microfibers as the frame from wood pulp (WP). The zein-protein-coated nanoparticles, CNF/zein, contribute in multiple ways to improve removal efficiency of the filters. First, the exposed functional groups of zein-protein help to trap air pollutants including toxic gaseous molecules via interaction mechanisms. Second, the nanoparticles with a high surface area promote the capture capability for small particulate pollutants. Meanwhile, the long-micron WP fibers forming a frame with large pores significantly reduce the pressure drop. Via adjusting the component ratios of in the Pickering emulsion, we report an optimized air filter with the high efficiency for capturing both types of pollutants: particulate matter (PM) and chemical gasses such as HCHO and CO, and the extremely low normalized pressure drop, that is, approximately 1/170 of the zein-based nano air filter by electrospinning. This study initiates a cost-effective strategy for forming a hierarchical nano- and microstructure, enabling high efficiency of capturing particulate pollutants of a wide size range and more species. More significantly, this is the first study in which Pickering emulsion is applied as a critical approach with integration of bio- and nano-technology to make high-performance, green air filters.

Antigen detection with thermosensitive hydrophilicity of poly(N-isopropylacrylamide)-grafted poly(vinyl chloride) fibrous mats

The static water contact angle of stimuli-responsive fibrous mats is used as a convenient index for rapid antigen detection.