Alginate encapsulated mesoporous silica nanospheres as a sustained drug delivery system for the poorly water-soluble drug indomethacin

We applied a combination of inorganic mesoporous silica material,frequently used as drug carriers,and a natural organic polymer alginate(ALG),to establish a sustained drug delivery system for the poorly water-soluble drug Indomethacin(IND).Mesoporous silica nanospheres(MSNs)were synthesized using an organic template method and then functionalized with aminopropyl groups through postsynthesis.After drug loading into the pores of aninopropyl functionalized MSNs(AP-MSNs),IND loaded AP-MSNs(IND-AP-MSNs)were encapsulated by ALG through the ionic interaction.The effects of surface chemical groups and ALG layer on IND release were systematically studied using scanning electron microscopy(SEM),transmission electron microscopy(TEM),nitrogen adsorption,zetapotential analysis and TGA analysis.The surface structure and surface charge changes of the ALG encapsulated AP-MSNs(ALG-AP-MSNs)were also investigated.The results showed that sustained release of IND from the designed drug delivery system was mainly due to the blockage effect from the coated ALG.We believe that this combination will help designing oral sustained drug delivery systems for poorly water-soluble drugs.

Constructing Z-schemeβ-Bi_(2)O_(3)/ZrO_(2)heterojunctions with 3D mesoporous SiO_(2)nanospheres for efficient antibiotic remediation via synergistic adsorption and photocatalysis

A series of Z-schemeβ-Bi_(2)O_(3)/ZrO_(2)hetero-junction composites containing three-dimensional(3D)mesoporous silica nanospheres(MSNs)were synthesized as efficient catalysts for antibiotic remediation.The obtained MSN/β-Bi_(2)O_(3)/ZrO_(2)ternary composites possess novel lamellar cross structure,which is well constructed byβ-Bi_(2)O_(3)nanosheets,3D MSNs,and ZrO_(2)nanoparticles.The optimal sample BZS-2(Bi∶Zr∶Si=1∶0.4∶0.33)shows an adsorptive-photocatalytic removal efficiency of 92.7%towards levofloxacin(LVF)and a total organic carbon(TOC)removal efficiency of 60.0%under simu-lated solar light irradiation for 100 min.BZS-2 can also remove 90.1%and 91.2%of tetracycline hydrochloride(TC)and oxytetracycline hydrochloride(OTC),respectively,and themaximum adsorptioncapacityof TCover BZS-2is almost 10 times that of-BiO.Theimprovement ofphotocatalytic activitycan bemainly attributed to the enhanced visible-light adsorption capacity and more efficientseparationof photogenerated electron-hole pairs.A possible Z-scheme photocatalytic mechanism of p BiO/ZrOheterojunctions based on valence band offset(AEvBo)andconduction band offset(EcBo)isproposed.This study provides an efficient way to construct novel mesoporous ternary photocatalyst with increased accessible surface area and active sites for treatment of antibiotics by synergistic adsorption and photocatalysis.

Effect of mesopores on solidification of sirolimus self-microemulsifying drug delivery system

To investigate the influence of mesopores towards the solidification of self-microemulsifying drug delivery system(SMEDDS), mesoporous silica nanospheres(MSNs) and Santa Barbara Amorphous-15(SBA-15) were compared. The MSNs had hydrodynamic size of 195.35 ± 5.82 nm, and pore diameter of 2.70 nm. The SBA-15 had hydrodynamic size of 2312.19 ± 106.93 nm, and pore diameter of 10.91 nm. The MSNs and SBA-15 showed similar loading efficiency of SMEDDS containing sirolimus(SRL). However,MSNs had higher drug dissolution and in vivo absorption, with relative bioavailability of 174.62%. Thus,the length of mesopores played a more important role in solidification of SMEDDS as compared with the pore diameter. This study suggests that the SMEDDS-MSNs can be a potential candidate for oral administration of hydrophobic drugs.