Chemical functionalization of nano fibrillated cellulose by glycidyl silane coupling agents: A grafted silane network characterization study

Thiol-functionalized cellulose for mercury polluted water remediation: Synthesis and study of the adsorption properties

Mercury pollution poses a global health threat due to its high toxicity, especially in seafood where it accumulates through various pathways. Developing effective and affordable technologies for mercury removal from water is crucial. Adsorption stands out as a promising method, but creating low-cost materials with high selectivity and capacity for mercury adsorption is challenging. Here we show a sustainable method to synthesize low-cost sulfhydrylated cellulose with ethylene sulfide functionalities bonded glucose units. Thiol-functionalized cellulose exhibits exceptional adsorption capacity (1325 mg g-1) and selectivity for Hg(II) over other heavy metals (Co, Cu, Zn, Pb) and common cations (Ca++, Mg++) found in natural waters. It performs efficiently across a wide pH range and different aqueous matrices, including wastewater, and can be regenerated and reused multiple times without significant loss of performance. This approach offers a promising solution for addressing mercury contamination in water sources.

Graft onto approaches for nanocellulose-based advanced functional materials

The resurgence of cellulose as nano-dimensional 'nanocellulose' has unlocked a sustainable bioeconomy for the development of advanced functional biomaterials. Bestowed with multifunctional attributes, such as renewability and abundance of its source, biodegradability, biocompatibility, superior mechanical, optical, and rheological properties, tunable self-assembly and surface chemistry, nanocellulose presents exclusive opportunities for a wide range of novel applications. However, to alleviate its intrinsic hydrophilicity-related constraints surface functionalization is inevitably needed to foster various targeted applications. The abundant surface hydroxyl groups on nanocellulose offer opportunities for grafting small molecules or macromolecular entities using either a 'graft onto' or 'graft from' approach, resulting in materials with distinctive functionalities. Most of the reviews published to date extensively discussed 'graft from' modification approaches, however 'graft onto' approaches are not well discussed. Hence, this review aims to provide a comprehensive summary of 'graft onto' approaches. Furthermore, insight into some of the recently emerging applications of this grafted nanocellulose including advanced nanocomposite formulation, stimuli-responsive materials, bioimaging, sensing, biomedicine, packaging, and wastewater treatment has also been reviewed.

Hyaluronic acid-modified yeast β-glucan particles delivering doxorubicin for treatment of breast cancer

Breast cancer is one of the most threatening cancers that poses a great risk to women's health. The anti-tumor drug doxorubicin (DOX) is one of commonly used drugs in the treatment of breast cancer. However, the cytotoxicity of DOX has always been an urgent challenge to be solved. In this study, we report an alternative drug delivery system delivering DOX for reducing its physiological toxicity by using the yeast β-glucan particle (YGP) with a hollow and porous vesicle structure. Briefly, amino groups were grafted onto the surface of YGP with the silane coupling agent, then the oxidized hyaluronic acid (OHA) was attached by Schiff base reaction to get HA-modified YGP (YGP@N=C-HA), finally DOX was encapsulated into YGP@N=C-HA to get DOX-loaded YGP@N=C-HA (YGP@N=C-HA/DOX). In vitro release experiments exhibited the pH-responsive DOX release from YGP@N=C-HA/DOX. Cell experiments displayed that YGP@N=C-HA/DOX had good killing effect on both MCF-7 and 4T1 cells and could be internalized into these cells through CD44 receptors, showing targetability to cancer cells. Furthermore, YGP@N=C-HA/DOX could effectively inhibit tumor growth and reduce the physiological toxicity of DOX. Thus, the YGP-based vesicle provides an alternative strategy for lowering the physiological toxicity of DOX in the medical treatment of breast cancer.

Cellulose/inorganic nanoparticles-based nano-biocomposite for abatement of water and wastewater pollutants

Nanostructured materials offer a significant role in wastewater treatment with diminished capital and operational expense, low dose, and pollutant selectivity. Specifically, the nanocomposites of cellulose with inorganic nanoparticles (NPs) have drawn a prodigious interest because of the extraordinary cellulose properties, high specific surface area, and pollutant selectivity of NPs. Integrating inorganic NPs with cellulose biopolymers for wastewater treatment is a promising advantage for inorganic NPs, such as colloidal stability, agglomeration prevention, and easy isolation of magnetic material after use. This article presents a comprehensive overview of water treatment approaches following wastewater remediation by green and environmentally friendly cellulose/inorganic nanoparticles-based bio-nanocomposites. The functionalization of cellulose, functionalization mechanism, and engineered hybrid materials were thoroughly discussed. Moreover, we also highlighted the purification of wastewater through the composites of cellulose/inorganic nanoparticles via adsorption, photocatalytic and antibacterial approach.

Enhancing bioactivity and stability of polymer-based material-tissue interface through coupling multiscale interfacial interactions with atomic-thin TiO2 nanosheets

Stable and bioactive material-tissue interface (MTF) basically determines the clinical applications of biomaterials in wound healing, sustained drug release, and tissue engineering. Although many inorganic nanomaterials have been widely explored to enhance the stability and bioactivity of polymer-based biomaterials, most are still restricted by their stability and biocompatibility. Here we demonstrate the enhanced bioactivity and stability of polymer-matrix bio-composite through coupling multiscale material-tissue interfacial interactions with atomically thin TiO2 nanosheets. Resin modified with TiO2 nanosheets displays improved mechanical properties, hydrophilicity, and stability. Also, we confirm that this resin can effectively stimulate the adhesion, proliferation, and differentiation into osteogenic and odontogenic lineages of human dental pulp stem cells using in vitro cell-resin interface model. TiO2 nanosheets can also enhance the interaction between demineralized dentinal collagen and resin. Our results suggest an approach to effectively up-regulate the stability and bioactivity of MTFs by designing biocompatible materials at the sub-nanoscale.

Electronic Supplementary Material

Supplementary material (further details of fabrication and characterization of TiO2 NSs and TiO2-ARCs, the bioactivity evaluation of TiO2-ARCs on hDPSCs, and the measurement of interaction with demineralized dentin collagen) is available in the online version of this article at 10.1007/s12274-022-5153-1.

Facile dispersion strategy to prepare polylactic acid/reed straw nanofiber composites with enhanced mechanical and thermal properties

The challenge of dispersing nanocellulose in hydrophobic polymers such as polylactic acid (PLA) still obstacles the further application of cellulose nanocomposites. An environment-friendly and facile wet-shearing pretreatment strategy without using any organic solvent was developed in this work. Silane modified lignocellulose nanofiber (SLCNF) was pre-dispersed into PLA by wet-shearing pretreatment, followed by extrusion process and the SLCNF could be dispersed extremely well in PLA matrices. SLCNF formed a crosslinked network and had an improved compatibility, which improved the mechanical and thermal properties of PLA composites. The tensile strength, elongation at break and thermal deformation temperature of the composites were increased by 12.6 %, 32.4 % and 9.1 °C, respectively. Moreover, SLCNF promoted the crystallization of PLA as a heterogeneous nucleating agent and the crystallinity was increased by about 40 %. This study provides an effective way to disperse nanocellulose in polymer matrix with high efficiency to enhance polymer-based composites.

Surface Wettability of Cellulose Sponges on Effective Oil Uptake

Designing absorbents having specific wettability toward both oil and water is the key for selective and effective oil absorption and removal. For this purpose, establishing explicit correlations between surface tension of oils and surface wettability of absorbent is crucial. In this study, we modified common low-cost cellulose sponges with various organosilanes to achieve a range of hydrophobicity/oleophilicity and then assessed their oil uptake selectivity and capability. Oil uptake was followed as mass uptake versus time and analyzed based on the spreading coefficient (S) of a liquid over a solid surface. The results showed that sponges needed to be hydrophobic, not necessarily superhydrophobic, to selectively absorb oil from an oil/water mixture. To achieve a fast uptake and a high uptake capacity, an S ≥ 0 was necessary, that is, when the sponges were completely wet by the oil. Increasing the porosity of cellulose sponge led to a slight increase in oil uptake capacity, and a greater increase resulted when bacterial cellulose sponges that consisted of smaller and more uniform voids/pores were used. S ≥ 0 could be used as a criterion for evaluating effective and rapid oil uptake for porous absorbents, especially for those containing heterogeneous pore structures, such as common cellulose sponges.

Microfibrillated Cellulose Grafted with Metacrylic Acid as a Modifier in Poly(3-hydroxybutyrate)

This work proposes a new method for obtaining poly(3-hydroxybutyrate) (PHB)/microfibrillated cellulose (MC) composites with more balanced properties intended for the substitution of petroleum-based polymers in packaging and engineering applications. To achieve this, the MC surface was adjusted by a new chemical route to enhance its compatibility with the PHB matrix: (i) creating active sites on the surface of MC with γ-methacryloxypropyltrimethoxysilane (SIMA) or vinyltriethoxysilane (SIV), followed by (ii) the graft polymerization of methacrylic acid (MA). The high efficiency of the SIMA-MA treatment and the lower efficiency in the case of SIV-MA were proven by the changes observed in the Fourier transform infrared FTIR spectra of celluloses. All modified celluloses and the PHB composites containing them showed good thermal stability close to the processing temperature of PHB. SIMA-modified celluloses acted as nucleating agents in PHB, increasing its crystallinity and favoring the formation of smaller spherulites. A uniform dispersion of SIMA-modified celluloses in PHB as a result of the good compatibility between the two phases was observed by scanning electron microscopy and many agglomerations of fibers in the composite with unmodified MC. The dual role of SIMA-MA treatment, as both compatibilizer and plasticizer, was pointed out by mechanical and rheological measurements. This new method to modify MC and obtain PHB/MC composites with more balanced stiffness–toughness properties could be a solution to the high brittleness and poor processability of PHB-based materials.