Covalently Bonded Ni Sites in Black Phosphorene with Electron Redistribution for Efficient Metal-Lightweighted Water Electrolysis

The metal-lightweighted electrocatalysts for water splitting are highly desired for sustainable and economic hydrogen energy deployments, but challengeable. In this work, a low-content Ni-functionalized approach triggers the high capability of black phosphorene (BP) with hydrogen and oxygen evolution reaction (HER/OER) bifunctionality. Through a facile in situ electro-exfoliation route, the ionized Ni sites are covalently functionalized in BP nanosheets with electron redistribution and controllable metal contents. It is found that the as-fabricated Ni-BP electrocatalysts can drive the water splitting with much enhanced HER and OER activities. In 1.0 M KOH electrolyte, the optimized 1.5 wt% Ni-functionalized BP nanosheets have readily achieved low overpotentials of 136 mV for HER and 230 mV for OER at 10 mA cm-2. Moreover, the covalently bonding between Ni and P has also strengthened the catalytic stability of the Ni-functionalized BP electrocatalyst, stably delivering the overall water splitting for 50 h at 20 mA cm-2. Theoretical calculations have revealed that Ni-P covalent binding can regulate the electronic structure and optimize the reaction energy barrier to improve the catalytic activity effectively. This work confirms that Ni-functionalized BP is a suitable candidate for electrocatalytic overall water splitting, and provides effective strategies for constructing metal-lightweighted economic electrocatalysts.

Crown ether-functionalized cellulose acetate membranes with potential applications in osseointegration

Due to its inherent properties and wide availability, cellulose acetate is an extremely competitive candidate for the production of polymeric membranes. However, for best results in particular applications, membrane modification is required in order to minimize unwanted interactions and introduce novel characteristics to the pristine polymer. In this study, the surface of commercial cellulose acetate membranes was functionalized with 4'-aminobenzo-15-crown-5 ether, using a covalent bonding approach. The main goal was the improvement of the membranes biomineralization ability, thus making them prospective materials for bone regeneration applications. The proposed reaction mechanism was confirmed by XPS and NMR analysis while the presence of the functionalization agents in the membranes structure was showed by ATR FT-IR and Raman spectra. The effects of the functionalization process on the morphology, thermal and mechanical properties of the membranes were studied by SEM, TGA and tensile tests. The obtained results revealed that the cellulose acetate membranes were successfully functionalized with crown ether and provided a good understanding of the interactions that took place between the polymer and the functionalization agents. Moreover, promising results were obtained during the Taguchi biomineralization studies. SEM images, EDX mapping and XRD spectra indicating that the CA-AB15C5 membranes have a superior Ca²⁺ ions retention ability, this causing an accentuated calcium phosphate deposition on the modified polymeric fibers, compared to the neat CA membrane.

Attomolar detection of hepatitis C virus core protein powered by molecular antenna-like effect in a graphene field-effect aptasensor

Biosensors based on graphene field-effect transistors have become a promising tool for detecting a broad range of analytes. However, their performance is substantially affected by the functionalization protocol. In this work, we use a controlled in-vacuum physical method for the covalent functionalization of graphene to construct ultrasensitive aptamer-based biosensors (aptasensors) able to detect hepatitis C virus core protein. These devices are highly specific and robust, achieving attomolar detection of the viral protein in human blood plasma. Such an improved sensitivity is rationalized by theoretical calculations showing that induced polarization at the graphene interface, caused by the proximity of covalently bound molecular probe, modulates the charge balance at the graphene/aptamer interface. This charge balance causes a net shift of the Dirac cone providing enhanced sensitivity for the attomolar detection of the target proteins. Such an unexpected effect paves the way for using this kind of graphene-based functionalized platforms for ultrasensitive and real-time diagnostics of different diseases.

Hydroxypicolinic acid tethered on magnetite core-silica shell (HPCA@SiO2@Fe3O4) as an effective and reusable adsorbent for practical Co(II) recovery

The soaring demand and future supply risk for cobalt (Co) necessitate more efficient adsorbents for its recycling from electronic wastes, as a cheaper and less hazardous option for its production. Herein, a magnetic adsorbent covalently tethered with 5-hydroxypicolinic acid (HPCA) as Co(II) ligand was developed. The magnetic component (Fe₃O₄) was protected with silica (SiO₂), then silanized with chloroalkyl linker and subsequently functionalized with HPCA via S_N2 nucleophilic substitution (HPCA@SiO₂@Fe₃O₄). Results from FTIR, TGA, EA, and XPS confirm the successful adsorbent preparation with high HPCA loading of 2.62 mmol g^-1. TEM-EDS reveal its imperfect spherical morphology with ligands well-distributed on its surface. HPCA@SiO₂@Fe₃O₄ is hydrophilic, water-dispersible and magnetically retrievable, which is highly convenient for its recovery. The Co(II) capture on HPCA@SiO₂@Fe₃O₄ involves monodentate coordination with carboxylate (COO^-) and lone pair acceptance from pyridine (aromatic -N = ) moiety of HPCA, with minor interaction from acidic silanols (Si-O^-). The binding occurs at 2 HPCA: 1 Co(II) ratio, that follows the Sips isotherm model with competitive Q_max = 92.35 mg g^-1 and pseudo-second order kinetics (k₂ = 0.0042 g mg^-1 min^-1). In a simulated LIB liquid waste, HPCA@SiO₂@Fe₃O₄ preferentially captures Co(II) over Li(I) with α_Li(I)^Co(II)=166 and Mn(II) with α_Mn(II)^Co(II)=55, which highlights the importance of HPCA for Co(II) recovery. Silica protection of Fe₃O₄ rendered the adsorbent chemically stable in acidic thiourea solution for its regeneration by preventing the deterioration of the magnetic component. Covalent functionalization averted ligand loss, which allowed HPCA@SiO₂@Fe₃O₄ to deliver consistent and reversible adsorption/desorption performance. Overall results demonstrate the potential of HPCA@SiO₂@Fe₃O₄ as a competitive and practical adsorbent for Co(II) recovery in liquid waste sources.

Covalent functionalization of decellularized tissues accelerates endothelialization

In the field of tissue regeneration, the lack of a stable endothelial lining may affect the hemocompatibility of both synthetic and biological replacements. These drawbacks might be prevented by specific biomaterial functionalization to induce selective endothelial cell (EC) adhesion. Decellularized bovine pericardia and porcine aortas were selectively functionalized with a REDV tetrapeptide at 10⁻⁵ M and 10⁻⁶ M working concentrations. The scaffold-bound peptide was quantified and REDV potential EC adhesion enhancement was evaluated in vitro by static seeding of human umbilical vein ECs. The viable cells and MTS production were statistically higher in functionalized tissues than in control. Scaffold histoarchitecture, geometrical features, and mechanical properties were unaffected by peptide anchoring. The selective immobilization of REDV was effective in accelerating ECs adhesion while promoting proliferation in functionalized decellularized tissues intended for blood-contacting applications.

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Covalent functionalization of the decellularized tissues with REDV peptide accelerates endothelialization.

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New covalent grafting method not inducing collagen cross-linking.

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Measurements through two photon miscroscopy allow the quantification of biological matrix bound peptide.

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The decellularized tissues can be changed by chemical procedures to promote specific cellular behaviour with ECM preservation.

Chemistry, properties, and applications of fluorographene

Fluorographene, formally a two-dimensional stoichiometric graphene derivative, attracted remarkable attention of the scientific community due to its extraordinary physical and chemical properties. We overview the strategies for the preparation of fluorinated graphene derivatives, based on top-down and bottom-up approaches. The physical and chemical properties of fluorographene, which is considered as one of the thinnest insulators with a wide electronic band gap, are presented. Special attention is paid to the rapidly developing chemistry of fluorographene, which was advanced in the last few years. The unusually high reactivity of fluorographene, which can be chemically considered perfluorinated hydrocarbon, enables facile and scalable access to a wide portfolio of graphene derivatives, such as graphene acid, cyanographene and allyl-graphene. Finally, we summarize the so far reported applications of fluorographene and fluorinated graphenes, spanning from sensing and bioimaging to separation, electronics and energy technologies.

Carbohydrate conjugation through microwave-assisted functionalization of single-walled carbon nanotubes using perfluorophenyl azides

Carbohydrate-functionalized single-walled carbon nanotubes (SWNTs) were synthesized using microwave-assisted reaction of perfluorophenyl azide with the nanotubes. The results showed that microwave radiation provides a rapid and effective means to covalently attach carbohydrates to SWNTs, producing carbohydrate-SWNT conjugates for biorecognition. The carbohydrate-functionalized SWNTs were furthermore shown to interact specifically with cognate carbohydrate-specific proteins (lectins), resulting in predicted recognition patterns. The carbohydrate-presenting SWNTs constitute a new platform for sensitive protein- or cell recognition, which pave the way for glycoconjugated carbon nanomaterials in biorecognition applications.