Loading cinnamon oil into pH-sensitive chitosan grafted mesoporous silica nanoparticles via supercritical carbon dioxide.

Stimulus-responsive mesoporous silica nanoparticles (MSNs) have displayed great potentiality for controlled-release and targeted drug delivery. In the current work, a supercritical fluid method was utilized to successfully prepare cinnamon oil loaded into chitosan grafted MSNs (CO@CS-MSNs). The influencing factors of drug loads, such as pressure, temperature, impregnation time and depressure time, were investigated. The structure of CO@CS-MSNs was demonstrated with Fourier-transform infrared (FT-IR) spectroscopy, transmission electron microscope (TEM), scanning electron microscopy (SEM), thermogravimetry (TG) as well as X-ray diffraction (XRD). The drug release assays in vitro at various pH conditions displayed that CO@CS-MSNs had an excellent pH-responsive release behavior, which confirmed that CO was loaded successfully into the CO@CS-MSNs. The findings indicated that the supercritical fluid approach is a non-destructive and efficient approach for stimulus-responsive MSNs, which is expected to further expand its application range.

Crystallization Thermodynamics of α-Lactose Monohydrate in Different Solvents.

It is common to find that some of the lactose in dairy powders and pharmaceutical tablets is present in the unstable amorphous state. Therefore, their crystallization thermodynamics in different solvents are particularly important. In this paper, the solubility of α-lactose monohydrate (α-LM) in 15 mono-solvents such as ethanol, isopropanol, methanol, 1-propanol, 1-butanol, 2-butanol, isobutanol, 1-pentanol, isoamylol, 1-hexanol, 1-heptanol, 1-octanol, propanoic acid, acetonitrile, and cyclohexanone was evaluated by using the gravimetric method in the temperature ranges from 274.05 K to 323.05 K at constant pressure (1 atm). In the given temperature range, the solubility of α-LM in these solvents increased with the rising of temperature, the highest solubility of α-LM was found in methanol (2.37 × 104), and the lowest was found in 1-hexanol (0.80 × 105). In addition, the increase of α-LM solubility in isopropanol was the largest. The sequence at 298.15 K was: methanol > 1-butanol > isopropanol > ethanol > 1-propanol > 1-heptanol > isobutanol > propionic acid > 1-pentanol > 1-octanol > acetonitrile > isoamylol > 2-butanol > cyclohexanone > 1-hexanol. Solvent effect analysis shows that the properties of α-LM are more important than those of solvents. The Apelblat equation, λh equation, Wilson model, and NRTL model were used to correlate the experimental values. The root-mean-square deviation (RMSD) and relative average deviation (RAD) of all models were less than 2.68 × 10−2 and 1.41 × 10−6, respectively, implying that the fitted values of four thermodynamic models all agreed well with the experimental values. Moreover, the thermodynamic properties of the dissolution process (i.e., dissolution Gibbs free energy (ΔdisG), molar enthalpy (ΔdisH), and molar entropy (ΔdisS)) for α-LM in selected solvents were determined. The results indicate that ΔdisH/(J/mol) (from 0.2551 to 6.0575) and ΔdisS/(J/mol/K) (from 0.0010 to 0.0207) of α-LM in these solvents are all positive, and the values of ΔdisH and ΔdisS. ΔdisG/(J/mol) (from −0.0184 to −0.6380) are all negative. The values were observed to decrease with rising temperatures, implying that α-LM dissolution is an endothermic, entropy-driven, and spontaneous process. The solid−liquid equilibrium data and dissolution thermodynamics of α-LM were obtained, which provide a basis for industrial production.

Enhanced Antioxidant Activity of Fresh Fruits through Salicylic Acid/ß-CD Hydroalcoholic Gels.

Oxidation is an important cause of fruit spoilage, and therefore improving the antioxidant capacity of fresh fruits is beneficial to their preservation. Herein, fresh-cut bananas were used as a type of fresh fruit and soaked in 75% hydroalcoholic gels containing salicylic acid (SA) or SA/ß-CD inclusion complex (SA/ß-CD). After treatment, they were placed in an atmosphere at 85% relative humidity at 20 °C for 12 days. A significant reduction in spoilage in bananas treated with the hydroalcoholic gels in the presence of SA/ß-CD was observed, compared with those treated with gels in the presence or absence of SA. The free-radical-scavenging performances of SA and its complex were investigated using the DPPH (1,1-diphenyl-2-picryl-hydrazil) method. Based on the results, the significant increase in antioxidant activity was attributed to the fact that the inclusion complex could break the intramolecular hydrogen bonding of SA, thus efficiently eliminating ROS in the fruits. The formation of the inclusion complex was confirmed by experiments and theoretical calculations. Our findings indicate that treatment with SA/ß-CD can provide an efficient method of maintaining postharvest quality and extending the shelf life of bananas.