FTIR spectra of pseudo-binary sodium borate glasses containing TeO2

Multifunctional Bagasse Foam with Improved Thermal Insulation and Flame Retardancy by a Borax-Induced Self-Assembly and Ambient Pressure Drying Technique

Cellulose foams are considered an effective alternative to plastic foam, because of their advantages of low density, high porosity, low thermal conductivity, and renewable nature. However, they still suffer from complex processing, poor mechanical properties, and flammability. As an agricultural waste, bagasse is rich in cellulose, which has attracted much attention. Inspired by the fact that borate ions can effectively enhance the strength of plant tissue by their cross-linking with polysaccharides, the present work designs and fabricates a series of multifunctional bagasse foams with robust strength and improved thermal insulation and flame retardancy via a unique borax-induced self-assembly and atmospheric pressure drying route using bagasse as a raw material, borate as a cross-linking agent, and chitosan as an additive. As a result, the optimized foam exhibits a high porosity (93.5%), a high hydrophobic water contact angle (150.4°), a low thermal conductivity (63.4 mW/(m·K) at 25 °C), and an outstanding flame retardancy. The present study provides a novel and inspiring idea for large-scale production of cellulose foams through an environmentally friendly and cost-effective approach.

Facile Fabrication of Cellulose Nanofibrils/Chitosan Beads as the Potential pH-Sensitive Drug Carriers

It is highly desirable to develop a safe, highly efficient, and biodegradable drug carrier with an enhanced drug transport efficiency. Cellulose nanofibrils (CNF) and chitosan (CS) composite hydrogels are promising candidate carriers with biological compatibility and non-cytotoxicity. Herein, the CNF/CS composite beads were prepared by dissolving cellulose and CS in LiBr molten salt hydrate and regenerating in ethanol. This preparation method is facile and efficient, and the obtained porous CNF/CS beads with the weight ratio of 8:2 exhibited a large specific surface area, uniform micro-nano-sized pores, strong mechanical property, and water absorption-resistance. Moreover, these beads as drug (tetracycline hydrochloride, TH) carriers showed a higher encapsulation efficiency (47.4%) at the TH concentration of 5 mg/mL in 24 h, and a higher drug loading rate (12.0%) than pure CNF and other CNF/CS beads prepared with different ratios. In addition, the TH releasing behavior of CNF/CS (8:2) beads fitted well into the zero-order, first-order, and Higuchi models under an acid condition, indicating that the drug release of these pH-sensitive beads was mainly affected by drug concentration under an acid condition. Therefore, these CNF/CS beads have great potential to be used as drug carriers for medical applications.

A pulp foam with highly improved physical strength, fire-resistance and antibiosis by incorporation of chitosan and CPAM

Bio-inspired borate cross-linked pulp foam (PF) with high porosity and low density can be widely used in many fields. However, PF is flammable, and lack of mechanical strength and antibacterial activity. To solve these issues, an ultra-strong PF was prepared by incorporation of chitosan and cationic polyacrylamide (CPAM). Results showed that the obtained PF exhibited highly improved mechanical properties (the compressive strength (485 kPa at a strain of 50%) was over 6 times higher compared with the borate cross-linked PF without chitosan and CPAM, and it was even higher than most of the reported cellulose-based porous materials). Also, the prepared PF has good performance on fire-retardance (hard to light), thermal insulation, antibiosis and sound absorption, due to the synergistic actions of borate, chitosan and CPAM. Additionally, spent liquor in preparing PF could be fully recycled, and thus this sustainable approach has potential for large-scale production of high-performance PF.

Construction of tellurium-doped mesoporous bioactive glass nanoparticles for bone cancer therapy by promoting ROS-mediated apoptosis and antibacterial activity

The commonly used treatment methods for bone cancer include chemotherapy, surgery and radiotherapy, but there are disadvantages such as nonspecific distribution, high toxicity of chemotherapy drugs, implantable infections and low monitoring. Nanoparticles are the new development direction of nanomedicine in cancer treatment. Structural characteristics of nanoparticles make it an excellent model for targeting and penetrating cancer-induced abnormal cell growth. In this study, a kind of novel and interesting tellurium ion doped mesoporous bioactive glasses (Te-MBG) nanoparticles were successfully synthesized by a simple sol-gel method, which had uniform spherical morphology (≈ 500 nm), high surface area (> 300 m²/g) and mesopore volume (> 0.30 cm³/g). Results found that Te doping does not affect the mineralization and degradation of the MBG nanoparticles. Meanwhile, compared to the undoped MBG, Te doped MBG not merely had the ability to promote MG63 cell apoptosis to inhibit bone cancer growth by ROS-mediated, but also had significant antibacterial activity. This all depends on the concentration of Te doping. It can be seen that Te-MBG nanoparticles can not only potentially fill bone defects caused by bone cancer removal, but also induce cancer cell apoptosis by tellurium release inducing reactive oxygen species (ROS) excessive production to inhibit bone cancer formation. This study provides a feasible strategy for the development of Te-MBG nanoparticles as well as their evaluation and basic research for bone cancer therapy.

Vibrational spectroscopy and density of K2O-B2O3-GeO2 glasses with variable B/Ge ratio

Glasses of the K₂O-B₂O₃-GeO₂ system were studied by means of Raman and IR spectroscopy. The density of the samples was measured and the dependence of the molar volume and atomic density on composition was calculated. Curve-fitting of Raman spectra was applied to obtain a definition of the main structural units formed in the system. The conditions for highly-coordinated boron and germanium atoms were obtained. It was shown that potassium cations remain connected to germanate structural units at a B/Ge ratio of up to 1, whereas the explicit redistribution of borate and germanate structural groupings becomes most noticeable only at a B/Ge ratio > 2.

Synergistic effects of boron-doped silicone resin and a layered double hydroxide modified with sodium dodecyl benzenesulfonate for enhancing the flame retardancy of polycarbonate

To improve the flame retardancy of polycarbonate (PC), a novel and environmentally friendly flame retardant was synthesized by combining boron-doped silicone resin (BSR) with a layered double hydroxide (LDH) modified with sodium dodecyl benzenesulfonate (SDBS) which was denoted as DBS-LDH/BSR. The structure of the hybrid was characterized by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS), which indicated that BSR was successfully combined with DBS-LDH. X-ray diffraction (XRD) studies showed that the reaction of BSR occurred only on the surface of DBS-LDH. In addition, scanning electron microscopy (SEM) was used to further verify the combination of DBS-LDH with BSR. PC exhibited the optimum flame retardancy following the incorporation of 10 wt% DBS-LDH/BSR (5 wt% DBS-LDH and 5 wt% BSR). Based on thermogravimetric analysis, the char residue of this PC composite in air at 750 °C increased to 3.60 wt%. Mechanical test showed that the DBS-LDH/BSR could affect the mechanical properties after incorporation into PC. According to the UL-94 vertical burning test, the flame retardant rating of the PC composite improved to V-0. Furthermore, the limiting oxygen index (LOI) value of the PC composite increased to 34%. According to the cone calorimeter test, the peak heat release rate (PHRR) dramatically decreased by 44%. The morphology of the PC composite after combustion was characterized by SEM, which revealed that the pores of the composite were smaller than those of pure PC. This result was attributed to the limited spread of oxygen and heat permeation. Thus, both DBS-LDH and BSR contributed to the synergistic effects of reducing the fire hazard of PC.

Boron-doped silicone resin (BSR) combined with a layered double hydroxide (LDH) modified with sodium dodecyl benzenesulfonate (SDBS) to improve the flame retardancy of polycarbonate (PC).

Mesoporous silica nanosphere supported platinum nanoparticles (Pt@MSN): one-pot synthesis and catalytic hydrogen generation

One-pot synthesis of mesoporous silica nanosphere (MSN) supported platinum nanoparticles (NPs) as catalysts for hydrogen generation from alkaline sodium borohydride is reported.

A low-temperature n-propanol gas sensor based on TeO2 nanowires as the sensing layer

TeO₂ nanowires with high surface-to-volume ratio and large mass production were synthesized by thermal evaporation method and showed a reversible response and quick response–recovery speed to n-propanol gas at low operating temperatures.