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.

Hollow mesoporous Ia3d silica nanospheres with single- unit-cell-thick shell： Spontaneous formation and drug delivery application

Mesoporous silica nanoparticles （MSNs） are promising for drug delivery and other biomedical applications owing to their excellent chemical stability and biocompatibility. For these applications, a hollow morphology with thin shell and open mesopores is preferred for MSNs in order to maximize the loading capacity of drugs. Herein we report a novel and direct synthesis of such an ideal drug delivery system in a dilute and alkaline solution of benzylcetyl- dimethylammonium chloride and diethylene glycol hexadecyl ether. The mixed surfactants can guide the formation of MSNs with cubic Ia3d mesostructure, and at a concentration of sodium hydroxide between 9.8 and 13.5 mM, hollow MSNs with uniform sizes of 90-120 nm and a single-unit-cell-thick shell are formed. A mechanism for the formation of the hollow Ia3d MSNs, designated as MMT-2, is proposed based on in situ small-angle X-ray scattering measurements and other analyses. MMT-2 exhibits much higher loading capacity of ibuprofen and degrades faster in simulated body fluid and phosphate buffered saline than non-hollow MSNs. The degradation of MMT-2 can be significantly retarded by modification with polyethylene glycol. More interestingly, the degradation of MMT-2 involves fragmentation instead of void formation, a phenomenon beneficial for their elimination. The results demonstrate the uniqueness of the hollow Ia3d MSNs and the great potential of the material for drug delivery and biomedical applications.

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.