Photocatalytic Degradation Mechanism of the Pharmaceutical Agent Salbutamol Using the Mn-Doped TiO2 Nanoparticles Under Visible Light Irradiation.

In the present work, the photocatalytic degradation of salbutamol [2-(tert-butylamino)-1-(4-hydroxyl-3-hydroxymethylphenyl)ethanol] under visible irradiation using Mn-doped TiO2 is investigated. The Mn-doped TiO2 nanoparticles were synthesized by the sol-gel method with ratios of 0.1, 0.2, and 0.3%. Significant characteristics, including the rutile/anatase phases ratio, specific surface area, and band gap energy, were due to the amount of Mn doping; the narrowest band gap energy of 2.80 eV was observed in 0.2% Mn-doped TiO2 with specific surface areas of 89.36 m2/g and 10.87/89.13 of rutile/anatase phases. The investigation involved salbutamol photocatalytic degradation, a kinetic study, and the identification of intermediate compounds. The results indicated that 0.2% Mn-doped TiO2 obtained the best salbutamol removal of 95% under an irradiation time of 180 min. Salbutamol slowly degraded to the intermediate compounds in the first 60 min (k = 0.0088 1/min), and these intermediate compounds were dramatically mineralized to small hydrocarbon fragments and carbon dioxide in the later irradiation times (k = 0.0179 1/min). According to the high-performance liquid chromatography-mass spectrometry (HPLC-MS) results, possible degradation pathways of salbutamol were proposed: 2-(tert-butylamino)-1-(3,4-dihydroxyphenyl)ethanone, 2-(tert-butylamino)-ethanol, and 2-(tert-butylamino)-1-(4-hydroxyl-3-hydroxymethylphenyl)ethanone were initially formed and then transformed to 2-(methylamino)-1-(3,4-dihydroxyphenyl)ethanone, 2-(tert-butylamino)-acetic acid, hydroquinone, and 1-(4-hydroxylphenyl)ethanol, respectively. The mineralization of all intermediate compounds was verified by 90% chemical oxygen demand (COD) reduction, and the effluent contained a relatively low COD concentration of 7.8 mg/L.

Chitosan and trimethyl chitosan chloride (TMC) as adjuvants for inducing immune responses to ovalbumin in mice following nasal administration.

Chitosan of different molecular weights (Chi-P, MW=2.7x10(5) g/mol and Chi-A, MW=5.0x10(5) g/mol) and trimethyl chitosan chloride (TMC) of various degree of quaternization (DQ) including TMC-20, TMC-40 and TMC-60 were evaluated as adjuvants for inducing of immune responses to ovalbumin (OVA). OVA in solution and in alum were used as controls. Groups of BALB/c mice were immunized on days 0, 7 and 14. The IgG and IgA titers were examined on days 0, 13 and 21. It was found that for both days 13 and 21, Chi-A could elicit higher IgG responses to OVA than Chi-P. On day 13, OVA in TMC-40 induced IgG responses significantly higher than that in solution, Chi-P and TMC-60. Moreover, OVA in TMC-40 could induce IgG responses higher than OVA in alum. Although a significant difference was not observed at day 21, OVA in TMC-40 was shown to induce higher IgG responses than that in TMC-20, TMC-60 and solution. The IgA responses were the most pronounced on day 21. Again, Chi-A could elicite higher IgA responses than Chi-P and TMC-40 induced the highest IgA responses. In conclusion, these findings demonstrate that both MW of chitosan and DQ of TMC influence the level of immune induction. TMC-40 shows to be the most potent adjuvant for intranasal administration.

In vitro evaluation of intestinal absorption of desmopressin using drug-delivery systems based on superporous hydrogels.

The aim of this study was to investigate and modify the potential of drug-delivery systems based on superporous hydrogel (SPH) for improving the intestinal transport of the peptide drug desmopressin in vitro. The swelling properties and mechanical strength of SPHs were studied. The release profile of desmopressin was investigated by changing the composition of excipients in the formulations. Subsequently, the ability of the SPH-based drug-delivery systems to enhance the transport of desmopressin across porcine intestine was performed in vitro. The swelling properties and mechanical strength of SPHs were affected by the addition of the disintregrant AcDiSol. This disintregrant reduced the swelling ratio to 10% and the time to 80% swelling was retarded by 3-5 min in comparison to the negative control. AcDiSol increased the mechanical strength, according to the increasing of penetration pressure value, the pressure that the punch can penetrate the gel, of the SPHs. The transport of desmopressin across the intestinal mucosa in vitro was enhanced four- and six-fold by applying SPH, with AcDiSol, in the absence and presence of the additional absorption enhancer trimethyl chitosan chloride, respectively, in comparison to the negative control. It is concluded that drug-delivery systems based on SPHs are promising for enhancing the intestinal absorption of desmopressin.