Phospholipid Bilayer Inspired Sandwich Structural Nanofibrous Membrane for Atmospheric Water Harvesting and Selective Release.

Atmospheric water harvesting (AWH) has been broadly exploited to meet the challenge of water shortage. Despite the significant achievements of AWH, the leakage of hydroscopic salt during the AWH process hinders its practical applications. Herein, inspired by the unique selective permeability of the phospholipid bilayer, a sandwich structural (hydrophobic-hydrophilic-hydrophobic) polyacrylonitrile nanofibrous membrane (San-PAN) was fabricated for AWH. The hydrophilic inner layer loaded with LiCl could capture water from the air. The hydrophobic microchannels in the outer layer could selectively allow the free transmission of gaseous water molecules but confine the hydroscopic salt solution in the hydrophilic layer, achieving continuous and recyclable water sorption/desorption. As demonstrated, the as-prepared AWH devices presented high-efficient adsorption kinetics from 1.66 to 4.08 g g-1 at 30% to 90% relative humidity. Thus, this work strengthens the understanding of the water transmission process along microchannels and provides insight into the practical applications of AWH.

Amphiphilic Cellulose Nanocrystals for Enhanced Pickering Emulsion Stabilization.

Sulfated cellulose nanocrystals (CNC) with high surface charge density are inadequate for stabilizing oil-water emulsions, which limits their applications as interfacial stabilizers. We performed end-group modification by introducing hydrophobic chains (polystyrene) to CNC. Results showed that the modified CNC are more effective in emulsifying toluene and hexadecane than pristine CNC. Various parameters were investigated, such as concentration of particles, electrolytes, and polarity of solvents on the characteristics of the emulsions. This study provides strategies for the modification of cellulose nanocrystals to yield amphiphilic nanoparticles that enhance the stability of emulsions. Such systems, bearing biocompatible and environmentally friendly characteristics, are attractive for use in a wide range of industries spanning food, biomedicine, pharmaceuticals, cosmetics, and petrochemicals.

Nanocellulose/scleroglucan-enhanced robust, heat-resistant composite hydrogels for oilfield water plugging.

In an oil exploitation process, hydrogel plugging agents can effectively reduce the water-oil intermixing, decrease water extraction volume, and enhance oil recovery rate. The practical applications of traditional polyacrylamide (PAM) hydrogel plugging agents in oilfield are limited by their non-biodegradability, poor mechanical performance, and inferior temperature-resistance. This work developed a mechanically stable and high-temperature-resistant composite hydrogel (STP) by incorporating biodegradable scleroglucan (Slg) and TEMPO-oxidized cellulose nanofibers (TOCN) in the PAM hydrogel. The addition of Slg conferred heat resistance to the PAM hydrogel, while TOCN reinforced the mechanical strength. Anti-aging analyses revealed that the STP endured for 108 h in a saline environment at 140 °C. In the water flooding characterization, the STP displayed a breakthrough pressure of 42.10 psi/ft. at a flow rate of 0.75 cm3/min. Under these extreme conditions, the plugging pressure reached 14.74 psi/ft., meeting the essential criteria for oilfield water plugging. This research demonstrates the potential of polysaccharides in the preparation of sustainable, tough, and heat-resistant water plugging materials.

Electrochemiluminescent lead biosensor based on GR-5 lead-dependent DNAzyme for Ru(phen)3(2+) intercalation and lead recognition.

An electrochemiluminescent (ECL) lead biosensor was developed based on GR-5 lead-dependent DNAzyme for lead recognition and intercalated ruthenium tris(1,10-phenanthroline) (Ru(phen)(3)(2+)) as the ECL probe. The thiol-modified substrate was first immobilized on the surface of the gold electrode via gold-sulfur self-assembly. Subsequently, the hybridization of DNAzyme and its substrate and the automatic intercalation of Ru(phen)(3)(2+) proceeded. Intercalated Ru(phen)(3)(2+) can transfer electrons through double-stranded DNA to the electrode and its electrochemiluminescence was excited with a potential step using tripropylamine as the coreactant. In the presence of lead, the substrate cleaves at the scissile ribo-adenine into two fragments. The dissociation of DNAzyme occurs, leading to the releasing of intercalated Ru(phen)(3)(2+) accompanied by a decrease in the intensity of electrochemiluminescence. A quantity of lead can be calculated from this decrease. The biosensor is highly sensitive and specific, along with an ultra-low limit of detection of 0.9 pM and a dynamic range from 2 to 1000 pM. It enables analysis of trace amounts of lead in serum samples. The combination of the intercalated-Ru(phen)(3)(2+) ECL probe and the cofactor-dependent DNAzyme may push the performance of cofactor-sensing tactics to the extreme.

3D coaxial printing of porous construct stacked with hollow filaments for heavy metal removal.

Biopolymers-based hydrogels/aerogels have been widely used for removing heavy metals from water. However, the adsorption efficiency is limited by the monolithic macroscopic structure due to low exposed adsorption sites and ion diffusion rate. In this study, we report a proof-of-concept micro-extrusion-based 3D coaxial printing technology to solve the aforementioned problems in heavy metal removal. The 3D printed grid-like architectures stacked with hollow filaments prepared by alginate and cellulose nanocrystal showed excellent heavy metals (including Cu, Zn, Cr, and Cd) removal performance over other common adsorbents. The Cu(II) adsorption was greatly influenced by the initial pH and ionic strength. It followed pseudo-second order kinetics and Langmuir isotherms models. The maximum adsorption capacity of the porous construct was found to be 97.22 mg∙g-1 at room temperature. Moreover, the equilibrium adsorption capacity and adsorption rate of Cu(II) in the hierarchical porous adsorbents (~68 mg∙g-1, 2.29×10-3 g∙mg-1∙min-1) were much higher than that in its corresponding solid chunk hydrogel (~48 mg∙g-1, 7.27×10-4 g∙mg-1∙min-1). It exemplifies that the 3D coaxial printing strategy for wastewater treatment enables shape-specific applications of functional hierarchical porous adsorbents.

Cellulose-based aerogel beads for efficient adsorption- reduction- sequestration of Cr(VI).

The reduction and sequestration of toxic Cr(VI) via a one-step process in an aqueous solution is critical to eliminate its environmental risk. In this study, amine functionalized cellulose-based aerogel beads (CGP) was developed for simultaneous and efficient adsorption- reduction- sequestration of Cr(VI). CGP showed a maximum Cr(VI) adsorption capacity of 386.40 mg/g at 25 °C due to its strong electrostatic attraction towards Cr(VI). The simultaneous Cr(VI) adsorption- reduction- sequestration performance of CGP over a wide Cr(VI) concentration range was examined. The mechanism was investigated in-depth via the analysis of adsorption kinetics, XPS spectra, and FTIR spectra. Moreover, the Cr immobilization stability of CGP after adsorption was evaluated in simulated neutral, acidic, and alkaline conditions. The effect of pH, temperature, ionic strength and the presence of interfering ions on CGP adsorption performance were investigated by batch adsorption experiments. Fixed-bed column adsorption study was performed to explore the application potential of CGP beads in a wastewater treatment process.

Carboxylated cellulose cryogel beads via a one-step ester crosslinking of maleic anhydride for copper ions removal.

In this study, we developed a one step protocol to prepare highly carboxylated and chemically crosslinked cellulose nanofibril (CNF) cryogel beads using maleic anhydride (MA). Fourier transform infrared spectroscopy (FTIR) and conductometric-potentiometric titration results confirmed the presence of carboxyl groups and ester linkages produced simultaneously during the ring open reaction of MA, yielding a carboxylic content of up to 2.78 mmol/g. The effect of CNF concentration on the morphology and wet mechanical strength of the crosslinked cryogel beads were also investigated, and results suggested that higher CNF concentration yielded a compact network that displayed a maximum compressive stress of 2800 Pa at 60 % strain. In addition, the heavy metal ions (i.e., Cu (II)) removal capacity, kinetics, mechanism as well as the recyclability of the resulted CNF-MA cryogel beads were examined.

Designing Highly Luminescent Cellulose Nanocrystals with Modulated Morphology for Multifunctional Bioimaging Materials.

Spherical cellulose nanocrystals (SCNs) and rod-shaped cellulose nanocrystals (RCNs) were extracted from different cellulose materials. The two shape forms of cellulose nanocrystals (CNs) were designed with a combination of isothiocyanate (FITC), and both the obtained FITC-SCNs and FITC-RCNs exhibited high fluorescence brightness. The surfaces of SCNs and RCNs were subjected to a secondary imino group by a Schiff reaction and then covalently bonded to the isothiocyanate group of FITC through a secondary imino group to obtain fluorescent cellulose nanocrystals (FITC-CNs). The absolute ζ-potential and dispersion stability of FITC-CNs (FITC-SCNs and FITC-RCNs) were improved, which also promoted the increase in the fluorescence quantum yield. FITC-RCNs had a fluorescence quantum yield of 30.7%, and FITC-SCNs had a morphological advantage (better dispersion, etc.), resulting in a higher fluorescence quantum yield of 35.9%. Cell cytotoxicity experiments demonstrated that the process of FITC-CNs entering mouse osteoblasts (MC3T3) did not destroy the cell membrane, showing good biocompatibility. On the other hand, FITC-CNs with good dispersibility can significantly enhance poly(vinyl alcohol) (PVA) and poly(lactic acid) (PLA); their mechanical properties were improved (the highest sample reached to 243%) and their fluorescent properties were imparted. This study provides a simple surface functionalization method to produce high-luminance fluorescent materials for bioimaging, multifunctional nanoenhancement/dispersion marking, and anticounterfeiting materials.

Tetrahedron-structured DNA and functional oligonucleotide for construction of an electrochemical DNA-based biosensor.

Tetrahedron-structured DNA (ts-DNA) in combination with a functionalized oligonucleotide was used to develop a "turn-on" biosensor for Hg(2+) ions. The ts-DNA provided an improved sensitivity and was used to block the active sites.

Functional nucleic acid-based electrochemiluminescent biosensor for interaction study and detection of Ag+ ions and cysteine.

An electrochemiluminescent biosensor was designed for the detection of Ag(+) ions and cysteine as well as their interaction study. To this end, a functional nucleic acid was designed for target recognition and probe intercalation.

A "turn-on" electrochemiluminescent biosensor for detecting Hg2+ at femtomole level based on the intercalation of Ru(phen)3(2+) into ds-DNA.

A well-designed oligonucleotide functionalized for Hg(2+) identification and Ru(phen)(3)(2+) intercalation is used to develop a "turn-on" electrochemiluminescent (ECL) biosensor for the determination of Hg(2+) in a drop (10 µL) of sample.