Bio-/Nanoimmobilization Platform Based on Bioinspired Fibrin-Bone@Polydopamine-Shell Adhesive Composites for Biosensing.

Inspired by blood coagulation and mussel adhesion, we report novel adhesive fibrin-bone@polydopamine (PDA)-shell composite matrix as highly efficient immobilization platform for biomacromolecules and nanomaterials. Fibrin, as a bioglue, and PDA, as a chemical adhesive, are integrated in a one-pot simultaneous polymerization consisting of biopolymerization of fibrinogen and chemical polymerization of dopamine. Fibrin fibers act as adhesive bones to construct scaffold, while PDA coat on the scaffold to form adhesive shell, generating 3D porous composite matrix with unique bone@shell structure. Two types of enzymes (glucose oxidase and acetylcholinesterase) and Au nanoparticles were adopted as respective model biomolecules and nanomaterials to investigate the immobilization capability of the matrix. The bionanocomposites showed high efficiency in capturing nanoparticles and enzymes, as well as significant mass-transfer and biocatalysis efficiencies. Therefore, the bionanocomposites exhibited significant potential in biosensing of glucose and paraoxon with limits of detection down to 5.2 µM and 4 ppt, respectively. The biological-chemical-combined polymerization strategy and composite platform with high immobilization capacity and mass-transfer efficiency open up a novel way for the preparation of high-performance bionanocomposites for various applications, in particular, biosensing.

Fully integrated ready-to-use paper-based electrochemical biosensor to detect nerve agents.

Paper-based microfluidic devices are gaining large popularity because of their uncontested advantages of simplicity, cost-effectiveness, limited necessity of laboratory infrastructure and skilled personnel. Moreover, these devices require only small volumes of reagents and samples, provide rapid analysis, and are portable and disposable. Their combination with electrochemical detection offers additional benefits of high sensitivity, selectivity, simplicity of instrumentation, portability, and low cost of the total system. Herein, we present the first example of an integrated paper-based screen-printed electrochemical biosensor device able to quantify nerve agents. The principle of this approach is based on dual electrochemical measurements, in parallel, of butyrylcholinesterase (BChE) enzyme activity towards butyrylthiocholine with and without exposure to contaminated samples. The sensitivity of this device is largely improved using a carbon black/Prussian Blue nanocomposite as a working electrode modifier. The proposed device allows an entirely reagent-free analysis. A strip of a nitrocellulose membrane, that contains the substrate, is integrated with a paper-based test area that holds a screen-printed electrode and BChE. Paraoxon, chosen as nerve agent simulant, is linearly detected down to 3µg/L. The use of extremely affordable manufacturing techniques provides a rapid, sensitive, reproducible, and inexpensive tool for in situ assessment of nerve agent contamination. This represents a powerful approach for use by non-specialists, that can be easily broadened to other (bio)systems.

Self-propelled activated carbon Janus micromotors for efficient water purification.

Self-propelled activated carbon-based Janus particle micromotors that display efficient locomotion in environmental matrices and offer effective 'on-the-fly' removal of wide range of organic and inorganic pollutants are described. The new bubble-propelled activated carbon Janus micromotors rely on the asymmetric deposition of a catalytic Pt patch on the surface of activated carbon microspheres. The rough surface of the activated carbon microsphere substrate results in a microporous Pt structure to provide a highly catalytic layer, which leads to an effective bubble evolution and propulsion at remarkable speeds of over 500 µm/s. Such coupling of the high adsorption capacity of carbon nanoadsorbents with the rapid movement of these catalytic Janus micromotors, along with the corresponding fluid dynamics and mixing, results in a highly efficient moving adsorption platform and a greatly accelerated water purification. The adsorption kinetics and adsorption isotherms have been investigated. The remarkable decontamination efficiency of self-propelled activated carbon-based Janus micromotors is illustrated towards the rapid removal of heavy metals, nitroaromatic explosives, organophosphorous nerve agents and azo-dye compounds, indicating considerable promise for diverse environmental, defense, and public health applications.