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We have studied the behavior and mechanism of the degradation of PEG–PLGA nanoparticles ..

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PLGA nanoparticles preparation and characterization

In order to evaluate the acoustic behavior ofCF-filled PLGA nanoparticles , testicular ultrasound imaging was performed using theB-Scan imaging mode at a frequency of 22 MHz and an MI of 0.06. Twogroups of five male rats were anesthetized intraperitoneally with10% chloral hydrate prior to agent injection. The transducer wasplaced on the testicle for real-time monitoring and 200 μl PLGAnanoparticles dispersed in deionized water were intra-testicularlyinjected. Ultrasound imaging was recorded during the injection. indicated that thelocal intensity of the acoustic signal continued to increase duringPLGA nanoparticle-injection into the testicle and the ability ofhollow PLGA nanoparticles to enhance ultrasound imaging was demonstrated. The results revealed that theenhancement image of testicular tissue following injection ofhollow PLGA nanoparticles was able to be sustained for ≥5 min. demonstrated theimaging behavior of deionized water injected into the testicle ofrats in the control group. There was almost no echo differencedetected prior to and following injection of degassed and deionizedwater.

137–144 Table 2 Influence of PLGA content on nanoparticles mean diameter ..

BLI, bioluminescence imaging; CH, chitosan; CLIO, cross-linked iron oxide; CT, computed tomography; Gd-DTPA, gadolinium diethylene-trianmine pentaacetic acid; FITC, fluoresceine isothiocyanate; FLI, fluorescence imaging; HA, hyaluronic acid; LMWP, low molecular weight protamine; Micron-sized particles, MPs; MR, magnetic resonance; MRI, magnetic resonance imaging; MSC, mesenchymal stem cells; MSNs, mesoporous silica nanoparticles; Nanoparticles, NPs, NSC, neural stem cell; PAA, poly(acrylic acid); PDMAAm, poly(N,N-dimethylacrylamide); PEG, poly(ethylene glycol); PEG-PLA, poly(ethylene glycol)-poly(L-glutamic acid); PEI, poly(ethyleneimine); PEI-SA, stearic acid-grafted polyethyleneimine copolymers; PET, positron emission tomography; PLGA, poly(lactide-co-glycolide); PLL, poly-L-lysine); PLMA: poly(DL-lactic acid-co-α,β-malic acid) copolymer; PMMA, poly(methylmethacrylate); , longitudinal relaxivity; , transverse relaxivity; RES, reticuloendothelial system; RITC: rhodamine B isothiocyanate; SPECT, single photon emission computed tomography; SPIONs, superparamagnetic iron oxide nanoparticles;, longitudinal relaxation time; , transverse relaxation time; TAs, transfection agents.

Synthesis and characterization of PLGA …

Synthesis and characterization of PLGA nanoparticles.

PLGA microcapsules are the most common type of UCAavailable at present. The polymeric shell improves the stability ofthe capsules, compared to that of those stabilized by amonomolecular layer of surfactant (,).Furthermore, PLGA microcapsules contain gas, which increases theirscattering power and leads to a high echogenicity due to the highcompressibility and low density of the gases (,).However, the large scale of PLGA microcapsules limits theirapplications. Sun ()reported that the superparamagnetic PLGA-iron oxide microcapsulesfor dual-modality ultrasound/magnetic resonance imaging had anaverage diameter of 885.6 nm. The endothelial gap of a tumor wasfound to be ~400–600 nm, which makes it difficult for microcapsulesto penetrate the vasculature and detect tumors (). To overcome this limitation, studieshave focused on developing PLGA capsules on a nanoscale (,).Néstor () preparedair-filled PLGA nanocapsules with a mean diameter of 370±96 nm andevaluated their echogenic power and stability . Kohl () prepared andevaluated multifunctional PLGA nanoparticles for photoacousticimaging. PLGA nanobubbles, of mean diameter 268 nm, were developedby Xu () forcancer targeting and imaging. In these previous studies, theimaging effects of PLGA nanoparticles were examined and the results suggested that the PLGA shell may improvenanocapsule stability. However, there were almost no systematicstudies investigating the imaging capacity of PLGAnanoparticles under varying conditions. Furthermore, to the best ofour knowledge, few studies have been conducted to investigate theproperties of PLGA nanoparticles in ultrasoundimaging (,–).

The present study was therefore designed to:) Prepare perfluoropropane(CF)-filled nanoparticles with abiodegradable polymeric shell composed of PLGA and )investigate the feasibility of using PLGA nanoparticles to enhanceultrasound imaging and .

(PLGA) nanoparticles and investigate the feasibility of using PLGA ..

Sep 20, 2011 · Synthesis of PLGA-b ..

PLGA hollow nanoparticles were prepared based on amodified double-emulsion solvent evaporation method (). For the first emulsion, 125 mg PLGAand 12.5 mg camphor were dissolved in 5 ml methylene chloride. Thepolymer was fully dissolved prior to the addition of 1 ml PVA (3%,w/v). The mixture was subsequently emulsified in an ice bath usinga Ultrasonic processing 04717 (Cole-Parmer, Vernon Hills, IL, USA)at 130 W for 180 sec, in pulse mode with sonication turned off for2 sec and on for 4 sec to prevent heat stacking. For the secondemulsion, the emulsified solution was added to 20 ml PVA (3%, w/v)and sonicated for 180 sec at 4 sec on, 2 sec off. Following thedouble emulsion, the resulting water-in-oil-in-water emulsion wasadded to 100 ml isopropyl alcohol (5%, v/v) and continually stirredfor 1 h to evaporate any organic solvent. Following evaporation,samples were collected using centrifugation (17,800 × g for 10 min)and washed three times with 5 ml deionized water. The precipitationwas subsequently flash frozen and lyophilized for 48 h. As themixture underwent the freeze-drying process, camphor sublimed outof the particles, leaving a void in their place. This hollow corewas filled with CF gas (Renjieling OpticalInstrument Co, Ltd., Shanghai, China) when later exposed toCF pressure.

The surface morphology of the nanoparticles wasinvestigated using an S-4800 field emission scanning electronmicroscope (FE-SEM; Hitachi, Tokyo, Japan). The PLGA nanoparticlesamples were dispersed in deionized water, spread over a piece ofaluminum foil and dried at room temperature. The samples weresubsequently sputter coated with a layer of gold using a fine coation sputter (JFC-1100; JEOL, Ltd, Tokyo, Japan) prior to FE-SEMimaging.

Plga | Nanocomposite | Nanoparticle
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In the present study, methylene chloride was used asa solvent, with high-power emulsification and high-speedcentrifugation, to produce PLGA nanoparticles markedly smaller thanthe microbubbles prepared using the traditional double-emulsionmethod (,). The average diameter of thenanoparticles fabricated was 152.0±58.08 nm, markedly smaller thanthe endothelial gap. In theory, particles ). It was therefore possible for thePLGA nanoparticles prepared in the present study to image thetarget tissue outside the vascular structures, overcoming thedrawbacks of conventional ultrasound contrast agents that are onlyable to image within the blood pool.

Synthesis and characterization of PLGA-Curcumin nanoparticles

The preliminary studies performedconfirmed the imaging effects of various concentrations of PLGAnanoparticles at 22 and 13 MHz. The results indicated that theidentical concentration of PLGA nanoparticles imaged better at afrequency of 22 MHz than at 13 MHz, which indicated that the PLGAnanoparticles were more suitable for use in high frequencies ofinsonification. Furthermore, low concentrations (0.125 mg/ml) ofPLGA nanoparticles were able to image for at the 120th sec,suggesting higher stability compared with that of UCAs made oflipid or protein. Therefore, there was also sufficient time for thePLGA nanoparticles to penetrate the endothelial cell gap into thetumor tissue and detect tumors efficiently when circulating inblood ().

PLGA Nanoparticles Formed by Single- or Double …

The micro-scale method of using a porogen to createvoids for accommodating gas in the particles was adapted for use inthe present study to produce hollow nanocapsules. Camphor and othersubstances that are able to sublime or decompose rapidly withoutthe generation of toxic reactions have the ability to form hollowswithin particles. Kwon and Wheatley () produced gas-loaded PLA nanoparticlesfor use as UCAs by using camphor. Néstor () prepared air-filled PLGA nanocapsulesusing ammonium bicarbonate as sublimable porogens. The PLGAnanoparticles used in the present study were prepared using camphoras the sublimable porogen, which produced a large hollow in theparticles. The hollows were subsequently filled withCF gas, producing higher echo reflection().

PLGA Nanoparticles Formed by Single- or ..

This work aimed to evaluate the influence of a freeze-drying process using different cryoprotectants on the structure of insulin loaded into poly(lactic--glycolic acid) (PLGA) nanoparticles and to assess the stability of these nanoparticles upon 6 months of storage following ICH guidelines. Insulin-loaded PLGA nanoparticles with a size around 450 nm were dehydrated using a standard freeze-drying cycle, using trehalose, glucose, sucrose, fructose, and sorbitol at 10% (w/v) as cryoprotectants. All formulations, except those nonadded of cryoprotectant and added with trehalose, collapsed after freeze-drying. The addition of cryoprotectants increased the nanoparticles stability upon storage. FTIR results showed that insulin maintained its structure after encapsulation in about 88%, decreasing to 71% after freeze-drying. The addition of cryoprotectants prior to freeze-drying increased insulin structural stability an average of up to 79%. Formulations collapsed after freeze-drying showed better protein stabilization upon storage, in special sorbitol added formulation, preserving 76, 80, and 78% of insulin structure at 4 °C, 25 °C/60% RH, and 40 °C/75% RH, respectively. Principal component analysis also showed that the sorbitol-added formulation showed the most similar insulin structural modifications among the tested storage conditions. These findings suggested that regarding nanoparticles stability, cryoprotectants are versatile to be used in a standard freeze-drying, however they present different performances on the stabilization of the loaded protein. Thus, on the freeze-drying of the nanoparticles field, this work gives rise to the importance of the process of optimization, searching for a balance between a good obtainable cake with an optimal structural stabilization of the loaded protein.

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