Development of pH-responsive Eudragit S100-functionalized silk fibroin nanoparticles as a prospective drug delivery system.

Silk fibroin nanoparticles (FNP) have been increasingly investigated in biomedical fields due to their biocompatibility and biodegradability properties. To widen the FNP versatility and applications, and to control the drug release from the FNP, this study developed the Eudragit S100-functionalized FNP (ES100-FNP) as a pH-responsive drug delivery system, by two distinct methods of co-condensation and adsorption, employing the zwitterionic furosemide as a model drug. The particles were characterized by sizes and zeta potentials (DLS method), morphology (electron microscopy), drug entrapment efficiency and release profiles (UV-Vis spectroscopy), and chemical structures (FT-IR, XRD, and DSC). The ES100-FNP possessed nano-sizes of ∼200-350 nm, zeta potentials of ∼ -20 mV, silk-II structures, enhanced thermo-stability, non-cytotoxic to the erythrocytes, and drug entrapment efficiencies of 30%-60%, dependent on the formulation processes. Interestingly, the co-condensation method yielded the smooth spherical particles, whereas the adsorption method resulted in durian-shaped ones due to furosemide re-crystallization. The ES100-FNP adsorbed furosemide via physical adsorption, followed Langmuir model and pseudo-second-order kinetics. In the simulated oral condition, the particles could protect the drug in the stomach (pH 1.2), and gradually released the drug in the intestine (pH 6.8). Remarkably, in different pH conditions of 6.8, 9.5, and 12, the ES100-FNP could control the furosemide release rates depending on the formulation methods. The ES100-FNP made by the co-condensation method was mainly controlled by the swelling and corrosion process of ES100, and followed the Korsmeyer-Peppas non-Fickian transport mechanism. Whereas, the ES100-FNP made by the adsorption method showed constant release rates, followed the zero-order kinetics, due to the gradual furosemide dissolution in the media. Conclusively, the ES100-FNP demonstrated high versatility as a pH-responsive drug delivery system for biomedical applications.

Boosting the ultraviolet shielding and thermal retardancy properties of unsaturated polyester resin by employing electrochemically exfoliated e-GO nanosheets.

In this work, a series of unsaturated polyester resin (UPRs)/electrochemically exfoliated graphene oxide (e-GO) polymer nanocomposites with different ratios of e-GO (0.05, 0.1, 0.15, and 0.2 wt%) were prepared via an in situ polymerization method. The surface morphology and structural and chemical properties of the original UPR and UPR/e-GO nanocomposites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and fourier transform infrared spectroscopy (FTIR). The positive influence of e-GO nanosheets on the mechanical properties, thermal stability, and anti-UV aging performance of UPR/e-GO nanocomposites was demonstrated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). The obtained results showed that the incorporation of e-GO nanosheets within the UPR matrix, despite the addition of e-GO at as low as 0.2 wt% comprehensively improves the advanced functional properties of UPR/e-GO nanocomposites as compared to the original UPR. In addition, artificial weathering testing of quartz-based artificial stone using UPR/e-GO 0.2 wt% showed excellent UV-resistant efficiency, supporting the use of e-GO nanosheets as an additive in manufacturing the industrial-scale UPRs-based artificial quartz stone samples for real outdoor applications.

Adsorptive Removal of Azo Dye New Coccine Using High-Performance Adsorbent-Based Polycation-Modified Nano-Alpha Alumina Particles.

The azo dyes new coccine (NCC) were successfully removed through the adsorption onto PVBTAC-modified α-Al2O3 particles. The optimal conditions of both the surface modification by PVBTAC adsorption and the NCC adsorption were thoroughly investigated. Formerly, polycations PVBTAC were adsorbed onto the nanosized α-Al2O3 particles at pH 8, NaCl 100 mM, with a contact time of 2 h, and initial concentration of 1000 ppm to modify the α-Al2O3 surface. Latterly, the NCC adsorptive removal was conducted at pH 8, NaCl 10 mM, α-Al2O3 adsorbent dosage of 3 mg mL-1, and a contact time of 45 min. Interestingly, the optimal pH of 8 potentially applies to treat real wastewater as the environmental pH range is often about 7-8. High removal efficiency and adsorption capacity of the NCC azo dyes were, respectively, found to be approximately 95% and 3.17 mg g-1 with an initial NCC concentration of 10 ppm. The NCC adsorption on the modified α-Al2O3 particles was well fitted with a Freundlich model isotherm. A pseudo-second kinetic was more suitable for the NCC adsorption on the PVBTAC-modified α-Al2O3 surface than a pseudo-first kinetic. The NCC adsorptive removal kinetic was also affirmed by the FT-IR spectra, based especially on the changes of functional group stretch vibrations of -SO3 - group in the NCC molecules and -N+(CH3)3 group in the PVBTAC molecules. The high reusability of the α-Al2O3 particles was proved to be higher than 50% after four generation times.