Silica-coating of fluorescent polystyrene microspheres by a seeded polymerization technique and their photo-bleaching property

Many chemical and biomedical systems require delivery and controlled release of small molecules, which cannot be achieved by conventional polyelectrolyte-based layer-by-layer capsules. This work proposes an innovative hybrid microcapsule by incorporating in situ formed silica nanoparticles within or on the shell. The influence of various experimental conditions on the stability, mechanical strength and morphology of capsules w as investigated, and characterised by SEM, TEM, XRD, EDX and FTIR. The multifunctional capabilities of formed capsules were examined by encapsulating a small molecule Rhodamine B (Rh-B), which could be further released by an ultrasonic trigger. The results show that in situ formed SiO2 nanoparticles through hydrolysis greatly reduced the permeability of the shell yet with increased mechanical strength and ultrasound response. SiO 2 nanoparticles were shown to be distributed on the surface or inside polyelectrolyte shell, acting as supports for free -standing capsules in both liquid and dry environment. Rapid Rh-B molecules release and the fragmentation of the capsule shells were observed under 50W ultrasound irradiation for a few seconds. Such innovative capsules with capability of small molecule encapsulation and high ultrasound sensitivity could be promising for many applications where pulse release of small molecules is required.

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“…15,49 However, as shown in Figure 5, the shell thickness increased drastically from a few nanometers to a few hundred nanometers (i.e. ~ 300 nm).…”

Section: Morphology and Structure Analysismentioning

confidence: 99%

Composite silica nanoparticle/polyelectrolyte microcapsules with reduced permeability and enhanced ultrasound sensitivity

2015

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“…8 Coating with amorphous silica: Calcia-doped ceria were coated with silica by two different methods, i.e., the sol-gel reaction of TEOS and acid hydrolysis of Na 2 SiO 3 . Silica coating by a sol-gel reaction of TEOS was conducted according to the previous papers [8][9][10] as follows. After dispersing calcia-doped ceria powder in TEOS/ethanol mixed solution, predetermined amount of water and 29 wt% ammonia aqueous solution were stepwise added.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and UV-shielding properties of silica-coated calcia-doped ceria nanoparticles via soft solution processes

et al. 2006

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White nanoparticles of calcia-doped ceria were prepared from the precipitate by reacting CeCl 3 -CaCl 2 mixed solution with NaOH solution at pH 12 and the oxidation with hydrogen peroxide solution at 40 • C, followed by the calcination at 700 • C for 1 h. The sample before calcination contained significant amount of OH − in the lattice and was yellow, but the powders calcined above 700 • C were white, indicating that cation defect formed by replacing O 2− with OH − played as the color center. It is confirmed that calcia-doped ceria showed much lower photocatalytic activity as well as lower generation of singlet oxygen under UV light irradiation than those with titania and zinc oxide. Calcia-doped ceria particles were coated with amorphous silica by means of sol-gel reaction technique using hydrolysis of tetraethylorthosilicate (TEOS) or acid hydrolysis of sodium silicate. The silica coating by sol-gel reaction with TEOS was much more efficient for the reduction of catalytic activity of ceria for the oxidation of organic materials without loss of UV-shielding ability than that by acid hydrolysis of sodium silicate.

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“…For ammonia-catalyzed synthesis of silica particles, the hydrolysis reaction occurs; [50]. Also, this mechanism holds for the formation of the silica layer on polymer microspheres as core [51]. The PEI molecules which are present on the surface PS microspheres only promote the interaction between PS microspheres and TEOS.…”

Section: Direct Formation Of Silica Shell On Ps Microspheresmentioning

confidence: 98%

“…When individual colloidal silica particles are present inside or on the surface of the polymer microspheres, the silica particles cannot provide a robust silica network structure. In order to fabricate physically robust silica shell layer, the sol-gel reaction, namely Stöber method, of silica source such as TEOS on the surface of the polymer microspheres is carried out [28,46,47]. Once such silica shell layer is fabricated on the polymer core, hollow silica spheres can be further prepared by removing the core polymer templates by high temperature calcination or selective dissolution using solvents.…”

Section: Direct Formation Of Silica Shell On Ps Microspheresmentioning

confidence: 99%

Polyelectrolyte-assisted synthesis of polystyrene microspheres by dispersion polymerization and the subsequent formation of silica shell

Hong

Lee

Rhym

et al. 2010

Journal of Colloid and Interface Science

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Silica-coating of fluorescent polystyrene microspheres by a seeded polymerization technique and their photo-bleaching property

Cited by 45 publications

References 28 publications

Composite silica nanoparticle/polyelectrolyte microcapsules with reduced permeability and enhanced ultrasound sensitivity

Composite silica nanoparticle/polyelectrolyte microcapsules with reduced permeability and enhanced ultrasound sensitivity

Synthesis and UV-shielding properties of silica-coated calcia-doped ceria nanoparticles via soft solution processes

Polyelectrolyte-assisted synthesis of polystyrene microspheres by dispersion polymerization and the subsequent formation of silica shell

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