Selective Ultrasonic Cavitation on Patterned Hydrophobic Surfaces

Belova, Valentina; Gorin, Dmitry A.; Shchukin, Dmitry G.; Möhwald, Helmuth

doi:10.1002/anie.201002069

Cited by 90 publications

(67 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The size distribution diagram is centered at 120 nm and its width is 60 nm (ca 5% of small ca 8 nm particles are visible in the area of smaller scales; assumingly, there are TiO 2 particles released from titanium sonotron). Additionally to the gas concentration in solvent, the bubble nucleation rate dN/dt depends on gas concentration, temperature, surface tension, pressure, hydrophobicity of the substrate surface [31-32]. This equation has two terms describing air dissolved in water and additional bubbling gas:

dN ∕ dt = {C_{1}}^{*} \exp (- Δ bold Δ E_{1} ∕ boldkT) + {C_{2}}^{*} \exp (- bold Δ E_{2} ∕ boldkT)

where C is gas concentration, ΔE = 4πσ 3 P -2 g(θ)/3 is the energy barrier for the bubble nucleation, T is the surrounding temperature, σ is the liquid/air surface tension.…”

Section: Resultsmentioning

confidence: 99%

“…An increase in pressure will decrease the energy barrier, also resulting in the increase of bubble nucleation, and is thus helpful for the nanoparticle formation. It was found that low wettability of materials (which is the case for more hydrophobic low soluble materials) forms the shape of bubble resulting jet directing to the particle surface which may increase explosion energy [32]. …”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Converting Poorly Soluble Materials into Stable Aqueous Nanocolloids

et al. 2010

View full text Add to dashboard Cite

Many chemical agents have low solubility which makes their dispersion, admixing and delivery difficult. Ball milling is often used to disperse such materials; however, dry powders are not always convenient for further applications [1]. For liquid hydrophobic materials, such as oil, there is a well established procedure of emulsification which allows for the stable dispersion of microdrops in water [2][3]. In this paper, we discuss a method for converting solid materials into stable aqueous nanocolloids with a particle size of ca 200 nm through simultaneous powerful ultrasonication and layer-by-layer (LbL) polyelectrolyte coating. It is a development of LbL microencapsulation introduced by G. Sukhorukov, E. Donath, F. Caruso, H. Möhwald, Most of these works are exploiting the formation of nano/engineered polyelectrolyte shells on pre-formed microtemplates with much larger diameters of 1 to 5 μm [11][12][13][14][15][16][17][18].There is a number of publications on micronizing drug or dye particles and building LbL shells on them, typically containing 4 to 10 polyelectrolyte bilayers and allowing a slow particle dissolution time from minutes up to 3-4 hours through adjustable capsule wall thickness (wall thickness of 20-50 nm) [9][10]19]. LbL shell coated dye particles were used as paint additives [11]. Soluble drugs, such as furosemide, nifedipine, naproxen , biotin, vitamin K3 and insulin were mechanically crushed into a dry powder and used for LbL shell assembly at a pH where they have low solubility in order to preserve the drug microcores from dissolution during the preparation [12][13][14][15]. Typical particle sizes of such a formulation were 2-10 micrometers [14]. In another approach, LbL microcapsules were assembled on sacrificed micro-cores (2-5 μm CaCO 3 , MnCO 3 , or silica). Then these cores were dissolved and the empty shells were loaded with proteins or drugs through pH controlled capsule wall opening [13][14][15]. Induced drug release is also possible with light responsive capsule opening [16]. Contrary to the first case of solid drug cores, these microshells contained a relatively low amount of loaded materials (1-5 vol %). Laser confocal microscopy allowed for the detailed studying of the structure of such microcapsules, proving the location of the loaded drugs and demonstrating their penetration into cells [17]. However, this successful development did not allow for the capsules to be sized on the nanometer scale.We are describing a method to prepare stable aqueous nanocolloids of low soluble materials (solubility less than 0.005 mg/mL) having particle diameters in the range of 150-250 nm. This approach is based on the powerful sonication of powders of low soluble materials in the presence of a polyelectrolyte which is adsorbing charging particles and preventing smaller and smaller pieces from re-aggregation. At the first preparation step, one has a colloidal dispersion of materials coated with a layer of polycations which provides a surface ξ-potential of ca +35 mV. Deposition of the second anio...

show abstract

dN ∕ dt = {C_{1}}^{*} \exp (- Δ bold Δ E_{1} ∕ boldkT) + {C_{2}}^{*} \exp (- bold Δ E_{2} ∕ boldkT)

where C is gas concentration, ΔE = 4πσ 3 P -2 g(θ)/3 is the energy barrier for the bubble nucleation, T is the surrounding temperature, σ is the liquid/air surface tension.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Converting Poorly Soluble Materials into Stable Aqueous Nanocolloids

et al. 2010

View full text Add to dashboard Cite

show abstract

“…One can choose additives which will increase in number of bubbles and decompose without damaging the original drug product. Another approach to increase sonication power is working under elevated pressure which may be reached with compressed gas atmosphere 22 . The free reactive groups of biocompatible polyelectrolytes (amine or acidic) at the outermost layer may help to bind PEG for longer particle circulation in blood or receptors for targeted drug delivery.…”

Section: Discussionmentioning

confidence: 99%

Top-down and bottom-up approaches in production of aqueous nanocolloids of low solubility drug paclitaxel

Pattekari

Zheng

Zhang

et al. 2011

Phys. Chem. Chem. Phys.

124

View full text Add to dashboard Cite

Nano-encapsulation of poorly soluble anticancer drug was developed with sonication assisted layer-by-layer polyelectrolyte coating (SLbL). We changed the strategy of LbL-encapsulation from making microcapsules with many layers in the walls for encasing highly soluble materials to using very thin polycation / polyanion coating on low soluble nanoparticles to provide their good colloidal stability. SLbL encapsulation of paclitaxel resulted in stable 100-200 nm diameter colloids with high electrical surface ξ-potential (of -45 mV) and drug content in the nanoparticles of 90 wt %. In the top-down approach, nanocolloids were prepared by rupturing powder of paclitaxel using ultrasonication and simultaneous sequential adsorption of oppositely charged biocompatible polyelectrolytes. In the bottom-up approach paclitaxel was dissolved in organic solvent (ethanol or acetone), and drug nucleation was initiated by gradual worsening the solution with the addition of aqueous polyelectrolyte assisted by ultrasonication. Paclitaxel release rates from such nanocapsules were controlled by assembling multilayer shells with variable thicknesses and are in the range of 10-20 hours.

show abstract

“…[ 75 ] Chemical patterning for changing the surface energy is most suitable to study further bubble growth. These bubbles would be expected to grow towards diameters of 100 μ m, and the contact area may be limited well below this size, thus allowing the three-phase boundary to be studied, which provides an additional control of surface treatment (or way of preparation) by ultrasound.…”

Section: Ultrasonic Modifi Cation Of Metalsmentioning

confidence: 99%

Ultrasonic Cavitation at Solid Surfaces

et al. 2011

Self Cite

View full text Add to dashboard Cite

In spite of the great potential of applying high-intensity ultrasound, which enables high-temperature and high-pressure chemistry with a reactor near room temperature and ambient pressure, sonochemistry at solid surfaces is at a weak stage of understanding with regards to the development of new materials and composite nanostructures. The science towards a quantitative understanding is only now emerging. On the other hand, in many applications an ultrasonic bath is used without thinking of the mechanism. Often surfaces are exposed to ultrasound for cleaning. Since ultrasonic treatment is not an exotic process and applicable even on large scale in industrial manufacturing, controlling the process may lead to new applications making use of the specially designed surface. This review is intended to summarize recent progress in this field and to point out most promising directions of ultrasound application for the development of new materials with functional surfaces.

show abstract

Selective Ultrasonic Cavitation on Patterned Hydrophobic Surfaces

Cited by 90 publications

References 36 publications

Converting Poorly Soluble Materials into Stable Aqueous Nanocolloids

Converting Poorly Soluble Materials into Stable Aqueous Nanocolloids

Top-down and bottom-up approaches in production of aqueous nanocolloids of low solubility drug paclitaxel

Ultrasonic Cavitation at Solid Surfaces

Contact Info

Product

Resources

About