Silica-based nanocapsules: synthesis, structure control and biomedical applications

Hsu, Benedict You Wei; Ren, Changliang; Xu, Li; Wang, John

doi:10.1039/c4cs00199k

Cited by 210 publications

(167 citation statements)

References 87 publications

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“…[1][2][3][4][5][6] These fascinating nanostructures have vast potential applications as catalysts or catalyst supports, 5, 7-11 drug carriers, [12][13][14][15][16][17] imaging agents, 18 as well as adsorbents and separation materials. [19][20][21][22][23] HSNs are often synthesized using templates that endow the hollow spheres with appropriate (inner) size and are referred to as hard or soft.…”

Section: Introductionmentioning

confidence: 99%

Single-micelle-templated synthesis of hollow silica nanospheres with tunable pore structures

Kruk

2015

RSC Adv.

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Hollow silica nanospheres (HSNs) were synthesized by using swollen micelles of Pluronic F108 (EO132PO50EO132) block copolymer surfactant as soft templates at low silica-precursor/surfactant ratios. An unprecedented tunability of the pore size was achieved in this single-micelle-templating synthesis through the initial synthesis temperature control in F108/toluene system, for which the pore diameter gradually increased from 16 to 44 nm upon decreasing the synthesis temperature from 25 to 14 °C. An additional pore size adjustment coupled with the change in the size of entrances to the nanospheres can be achieved by selecting the hydrothermal treatment temperature, as shown for the synthesis at 25 °C. The inner diameter of the hollow nanospheres can also be modified by changing the silica alkoxide precursor used or its ratio to the surfactant. Moreover, the formation of hollow nanospheres, their inner void size and its temperature adjustability depend on the swelling agent used. In the cases of xylene and ethylbenzene swelling agents, the pore size adjustment was complicated by the morphology change from loose aggregates of hollow spheres to consolidated particles with multiple mesopores as the temperature was lowered. On the other hand, these swelling agents afforded nanospheres of particularly large diameter (22-26 nm) at 25 °C. Less potent swelling agents (1,3,5-triisopropylbenzene and cyclohexane) afforded largely disordered consolidated structures instead of single-micelle-templated nanospheres. The work demonstrated the potential of Pluronic F108 combined with an appropriate swelling agent to template silica nanospheres with hollow interiors of size and accessibility adjustable in a wide range through simple temperature control.

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Section: Introductionmentioning

confidence: 99%

Single-micelle-templated synthesis of hollow silica nanospheres with tunable pore structures

Kruk

2015

RSC Adv.

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“…[44][45][46][47] As is known, the shell structure of capsules directly affect their application properties, such as mass transfer rate, 48 adsorption capacity, 49,50 and mechanical stability, 30 and so on. [44][45][46][47] As is known, the shell structure of capsules directly affect their application properties, such as mass transfer rate, 48 adsorption capacity, 49,50 and mechanical stability, 30 and so on.…”

Section: Preparation and Characterization Of Z-tio 2 Microcapsulesmentioning

confidence: 99%

MOF-templated rough, ultrathin inorganic microcapsules for enzyme immobilization

et al. 2015

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Ultrathin titania microcapsules with rough surfaces were prepared by using a metal-organic framework (ZIF-8) as one kind of hard template to mediate the structures of the microcapsule shell. Specifically, CaCO 3 particles were first coated with tannic acid (TA) followed by the deposition of hydrophobic ZIF-8 and another TA layer, the obtained particles were then assembled with protamine/TiO 2 bilayers through biomimetic mineralization. Finally, the microcapsules (Z-TiO 2 ) were obtained after simultaneously removing CaCO 3 and ZIF-8 templates using ethylenediaminetetraacetic acid (EDTA). The coordination interaction between TA and ZIF-8 ensured the robust templating which endowed the microcapsules with a rough surface and an ultrathin microcapsules shell (100 nm) with 4.4 nm pore size. Moreover, the surface roughness of microcapsules can be regulated by changing the size of ZIF-8 crystals. The microcapsules were then utilized to immobilize penicillin G acylase (PGA). And PGA@Z-TiO 2 retained 69% activity of equivalent free PGA with a loading capacity of 160 mg g À1 . The PGA@Z-TiO 2 microcapsules exhibited superior reusability: after recycling 8 times, the conversion of the enzymatic reaction remained 36.0%, which was twice higher than that of PGA@TiO 2 (14.7%). Moreover, compared with free PGA and PGA@TiO 2 microcapsules, PGA@Z-TiO 2 microcapsules exhibited higher thermal and storage stability. After storing for 60 days, the relative activity of PGA@Z-TiO 2 remained 89.6%, which was higher than that of free PGA (34.5%) and PGA@TiO 2 (73.6%). ZIF-8 can be envisioned to be a novel class of hard template for preparing a broad variety of microcapsules with different hierarchical structures. † Electronic supplementary information (ESI) available: SEM and TEM images of ZIF-8 particles, nitrogen adsorption-desorption isotherms of ZIF-8 particles, and UV-vis spectra of the assembled multilayer film. See Fig. 12 Recycling stability of PGA@Z-TiO 2 and PGA@TiO 2 (a), temperature stability (b), pH stability (c), and storage stability (d) of free PGA, PGA@Z-TiO 2 and PGA@TiO 2 MCs.

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“…The advantage of mesoporous silica hollow capsules (MSHCs) over mesoporous silica particles as drug carriers is the simultaneous reduction in the required dose and dosing frequency because of their higher capacity for drug loading [4]. Both loading and release properties of MSHCs, as well as their targeted delivery and controlled release performance, have been extensively studied [20][21][22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

High-yield hydrothermal synthesis of mesoporous silica hollow capsules

Kato

2016

Microporous and Mesoporous Materials

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Silica-based nanocapsules: synthesis, structure control and biomedical applications

Cited by 210 publications

References 87 publications

Single-micelle-templated synthesis of hollow silica nanospheres with tunable pore structures

Single-micelle-templated synthesis of hollow silica nanospheres with tunable pore structures

MOF-templated rough, ultrathin inorganic microcapsules for enzyme immobilization

High-yield hydrothermal synthesis of mesoporous silica hollow capsules

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