Search

Traditionally in superhydrophobic surfaces history, the focus has frequently settled on the use of complex processing methodologies using nonbiodegradable and costly materials. In light of recent events on lab-on-paper emergence, there are now some efforts for the production of superhydrophobic paper but still with little development and confined to the fabrication of flat devices. This work gives a new look at the range of possible applications of bioinspired superhydrophobic paper-based substrates, obtained using a straightforward surface modification with poly(hydroxybutyrate). As an end-of-proof of the possibility to create lab-on-chip portable devices, the patterning of superhydrophobic paper with different wettable shapes is shown with low-cost approaches. Furthermore, we suggest the use of superhydrophobic paper as an extremely low-cost material to design essential nonplanar lab apparatus, including reservoirs for liquid storage and manipulation, funnels, tips for pipettes, or accordion-shaped substrates for liquid transport or mixing. Such devices take the advantage of the self-cleaning and extremely water resistance properties of the surfaces as well as the actions that may be done with paper such as cut, glue, write, fold, warp, or burn. The obtained substrates showed lower propensity to adsorb proteins than the original paper, kept superhydrophobic character upon ethylene oxide sterilization and are disposable, suggesting that the developing devices could be especially adequate for use in contact with biological and hazardous materials.

The guanidine-based antimicrobial polymers were grafted onto the surface of beeswax latex particles stabilized with or without amphoteric surfactant, n-dodecyl-N,N-dimethylglycine. N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) was used as a coupling reagent to introduce the covalent bonding or ensure sufficient binding force. The resulting novel beeswax latexes were utilized as a dual-functional paper additive, which improved both water-vapor resistance and antimicrobial activities of the paper. Compared with control sample, the water vapor transmission rate of the paper was reduced significantly. The antimicrobial activity of paper against E. coli was also improved substantially even at a low dosage of the beeswax latex derivatives (20 mg/g fiber).

A flexible free-standing graphene/SnO₂ nanocomposites paper (GSP) was prepared by coupling a simple filtration method and a thermal reduction together for the first time. Compared with the pure SnO₂ nanoparticles, the GSP exhibited a better cycling stability, because the graphene with high mechanical strength and elasticity can work as a buffer to prevent the volume expansion and contraction of SnO₂ nanoparticles during the Li⁺ insertion/extraction process. Meanwhile, compared with single graphene paper, the GSP showed a higher capacity because of the hybridizing with higher capacity SnO₂ nanoparticles. The excellent electrochemical performance of the GSP as an anode material in Li-ion battery was obtained. The as-prepared GSP shows a great potential for flexible Li-ion batteries.

Paper is one of the oldest and most abundant materials known to man. Recently, there has been a considerable interest in creating paper devices by combining paper with other functional materials. In this letter, we demonstrate a simple fabrication technique to create water-resistant ferro-patterns on wax paper using CO(2) laser ablation. A resolution of about 100 μm is achieved which is mostly limited by the cellulose fiber size (~50 μm) in the wax paper and can be improved by using a smaller cellulose matrix. Laser ablation results in modification of surface morphology and chemistry, leading to a change in surface energy. We also present a 2D model for ferrofluid deposition relating the size of the pattern to the amount of ferroparticles deposited on the surface. Finally, a paper gripper is presented to demonstrate advantages of our technique, which allows microscale patterning and machining in a single step.

Cationic polymers with various structures have been widely investigated in the areas of medical diagnostics and molecular biology because of their unique binding properties and capability to interact with biological molecules in complex biological environments. In this work, we report the grafting of a linear cationic polymer from an atom transfer radical polymerization (ATRP) initiator bound to cellulose paper surface. We show successful binding of ATRP initiator onto cellulose paper and grafting of polymer chains from the immobilized initiator with ATRP. The cellulose paper grafted polymer was used in combination with PicoGreen (PG) to demonstrate detection of nucleic acids in the nanogram range in homogeneous solution and in a biological sample (serum). The results showed specific identification of hybridized DNA after addition of PG in both solutions.

Vapor detection of hydrogen peroxide still remains challenging for conventional sensing techniques, though such vapor detection implies important applications in various practical areas, including locating IEDs. We report herein a new colorimetric sensor system that can detect hydrogen peroxide vapor down to parts per billion level. The sensory materials are based on the cellulose microfibril network of paper towels, which provide a tunable interface for modification with Ti(IV) oxo complexes for binding and reacting with H(2)O(2). The Ti(IV)-peroxide bond thus formed turns the complex from colorless to bright yellow with an absorption maximum around 400 nm. Such complexation-induced color change is exclusively selective for hydrogen peroxide, with no color change observed in the presence of water, oxygen, common organic reagents or other chelating reagents. This paper-based sensor material is disposable and one-time use, representing a cheap, simple approach to detect peroxide vapors. The reported sensor system also proves the technical feasibility of developing enhanced colorimetric sensing using nanofibril materials that will provide plenty of room to enlarge the surface area (by shrinking the fiber size), so as to enhance the surface interaction with gas phase.

In this work, we report a low-cost technique via simple rapid-mixture polymerization of aniline using graphene oxide (GO) and graphene papers as substrates, respectively, to fabricate free-standing, flexible GO-polyaniline (PANI) and graphene-PANI hybrid papers. The morphology and microstructure of the obtained papers were characterized by FESEM, FTIR, Raman, and XRD. As results, nanostructural PANI can be deposited on the surfaces of GO and graphene papers, forming thin, lightweight, and flexible paperlike hybrid papers. The hybrid papers display a remarkable combination of excellent electrochemical performances and biocompatibility, making the paperlike materials attractive for new kinds of applications in biosciences.

Lignocellulosic biomass offers economic and environmental advantages over corn starch for biofuels production. However, its fractionation currently requires energy-intensive pretreatments, due to the lignin chemical resistance and complex cell wall structure. Recently, ionic liquids have been used to dissolve biomass at high temperatures. In this study, thin sections of poplar wood were swollen by ionic liquid (1-ethyl-3-methylimidazolium acetate) pretreatment at room temperature. The samples contract when rinsed with deionized water. The controlled expansion and contraction of the wood structure can be used to incorporate enzymes and catalysts deep into the wood structure for improved pretreatments and accelerated cellulose hydrolysis. As a proof of concept, silver and gold nanoparticles of diameters ranging from 20 to 100 nm were incorporated at depths up to 4 mum. Confocal surface-enhanced Raman images at different depths show that a significant number of nanoparticles were incorporated into the pretreated sample, and they remained on the samples after rinsing. Quantitative X-ray fluorescence microanalyses indicate that the majority of nanoparticle incorporation occurs after an ionic liquid pretreatment of less than 1 h. In addition to improved pretreatments, the incorporation of materials and chemicals into wood and paper products enables isotope tracing, development of new sensing, and imaging capabilities.

This paper describes the use of thread as a matrix for the fabrication of diagnostic assay systems. The kinds of thread used for this study are inexpensive, broadly available, and lightweight; some of them are already familiar materials in healthcare. Fluids wick along these threads by capillary action; no external power source is necessary for pumping. This paper demonstrates three designs for diagnostic assays that use different characteristics of the thread. The first two designs-the "woven array" and the "branching design"-take advantage of the ease with which thread can be woven on a loom to generate fluidic pathways that enable multiple assays to be performed in parallel. The third design-the "sewn array"-takes advantage of the ease with which thread can be sewn through a hydrophobic polymer sheet to incorporate assays into bandages, diapers and similar systems. These designs lead to microfluidic devices that may be useful in performing simple colorimetric assays that require qualitative results. We demonstrate the function of thread-based microfluidic devices in the context of five different colorimetric assays: detection of ketones, nitrite, protein, and glucose in artificial urine, and detection of alkaline phosphatase in artificial plasma.

An electrochromic-type electronic paper was prepared using nanocomposites that consisted of silica nanoparticles (silica 60 wt %) and polyamide pulp. Its light scattering, ion transport, and aqueous electrolyte retention characteristics were examined. As a result, the shape of the nanocomposites was completely self-standing, though it could be impregnated with about nine times as much water on a weight basis. Moreover, its light scattering property was extremely similar to paper. Because of the impregnation of a large amount of water, the ion transport property of the nanocomposites was the same as that of the electrolyte solution without the nanocomposites. The nanocomposites was impregnated using an aqueous solution in which bismuthyl perchlorate (redox species), copper perchlorate, perchloric acid, sodium perchlorate, hydroquinone (electron mediator) and 2-buthyne-1,4-diol (leveling agent) were dissolved. The electronic paper was then prepared by sandwiching the nanocomposites between an indium-tin-oxide transparent electrode and a copper sheet. This electronic paper utilizes the reversible codeposition reaction of black Bi-Cu from bismuthyl perchlorate and copper(II) ions. The characteristics of this electronic paper were examined, and excellent characteristics with a white reflectivity of 65%, black reflectivity of 6.4%, contrast ratio of 10:1, operating life of over 1 x 10(6) cycles and open-circuit memory of at least 1 month were obtained. In addition, its driving voltage was 1.2 V, and the write time was 500 ms.