An efficient preparation of porous polymeric microspheres by solvent evaporation in foam phase

This paper reports an efficient method of preparing porous polymeric microspheres by solvent evaporation in foam phase,in which phase separation between polymer and porogen occurs in foam phase instead of that in water phase by using the traditional solvent eva poration method.The method provides outstanding features,including being time-saving,of high-yield and able for continuous production,in which formation of porous polymeric microspheres finished within 3 min with a high production yield up to approximate 95 wt% and the process was able to be developed into a continuous process for production of porous polymeric microspheres.It was also universal to non-crosslinked polymers since the method is a development on the traditional emulsion solvent evaporation method.The new method is efficient and can be used potentially on the industrial scale for continuous production of porous polymeric microsphere s.

Application of solvent evaporation technique for pure drug crystal spheres preparation

An innovative application ofthe solventevaporation technique was suggested.Solventevaporation tech nique is a technique for drug encapsulation and nanosphere preparation.The widely used technique is also facing the problem of low actual drug entrapment percent,which is not economic from the industrial view.The goal of this work is trying to use the advantage of this technique concerning the product sphericity and the ability to control particle size,to prepare a drug as pure crystals spheres.Ibuprofen is selected as a model drug.The spheres are formed by using Polyvinyl pyrrolidone(PVP)or Polyethylene glycol(PEG)as an anti-aggregating agent but not formed on using tween or span.Particle size and actual drug content depend on the concentrations the anti-aggregating agent used.Surfaces of the drug crystal spheres are porous with empty sphere internal structure on using PvP but spongy and rough on using PEG.The drug has its identity chemical form in the drug crystal spheres.IR scan of spheres prepared on using PEG showed a characteristic ether peak.DSC showed melting endothermic peak of PEG,but X-ray showed minor change in the drug crystal patterns.Drug release profiles from crystal spheres prepared with the same anti-aggregating agent are close to each other.The drug release profiles from drug crystal spheres prepared by using PEG are more controlled than that prepared by using PVP.The drug release mechanism is diffusion.It was concluded that,the same technique could be suggested for preparation ofother biomedical material in pure crystals spheres with controlled particle size.These properties may encourage to prepare very small particles with spherical shape for inhalation or injection as an innovative particle technology application for the widely used technique.

Low Temperature Solvent Evaporation-induced Crystallization Synthesis of Nanocrystalline TiO_2 Photocatalyst

A novel and efficient methodology for obtaining highly active photocatalyst of bi phase TiO 2 with small particle size and high specific surface area was developed by solvent evaporation induced crystallization (SEIC) method at low temperature. The prepared TiO 2 powder was characterized with X ray diffraction (XRD), transmission electron microscopy (TEM) and BET surface areas. The photocatalytic activity was evaluated by the photocatalytic oxidation of acetone in air. The results showed that the photocatalytic activity of the TiO 2 powder prepared by this method approached that of Degussa P25. This may be attributed to the fact that the prepared TiO 2 powder had larger specific surface areas (265 m 2·g -1 ) and smaller crystallite size (about 5 nm), but relatively low crystallinity, as compared with Degussa P25.

Omni-functional simultaneous interfacial treatment for enhancing stability and outgassing suppression of lithium-ion batteries

Ni-rich layered oxides in lithium-ion batteries have problems with gas generation and electrochemical performance reduction due to residual lithium's reaction on the surface with the electrolyte.To address this issue,in this study,the Acid solvent evaporation(AsE)method has been proposed as a potential method to remove residual lithium while promoting the formation of a new LiNO_(3)-derived coating layer on the cathode surface.The reduction of residual lithium using the ASE method and the construction of a LiNO_(3)-derived coating layer suppresses gas evolution caused by the side effects of the electrolyte,improves electrochemical performance,and improves thermal stability by facilitating the smooth movement of lithium ions.Furthermore,the structural stability and resistance change due to the LiNO_(3)-derived coating layer effects is guaranteed through cycling and DCIR of the pouch cell.As a result,compared to Pristine,the capacity retention of coin cells increased by 8%after 100 cycles,and pouch cells increased by 25%after 160 cycles.In addition,after cycling the pouch cell,CO_(2) gas has significantly reduced by about 30%compared to Pristine using gas chromatography.The ASE method effectively forms a robust LiNO_(3)-derived coating layer on the cathode active material,which helps minimize electrolyte reactivity,suppress ,CO_(2) emissions,enhance surface structure stability,improve thermal stability,and improveoverallbatteryperformance.

Preparation of 20 (S)-protopanaxadiol PLGA Nanoparticles

[Objectives]To prepare 20(S)-protopanaxadiol PLGA nanoparticles(20(S)-PPD-PLGA-NPs).[Methods]20(S)-PPD-PLGA-NPs were prepared by emulsion solvent evaporation method,and the optimal formulation was screened by Box-Behnken experiment with particle size and drug loading as the indicators through single factor experiment,and the drug release in vitro was carried out.[Results]The average diameter of the nanoparticles was(119.60±2.29)nm and the polydispersity index was(0.12±0.02),the size was uniform.The encapsulation efficiency and drug loading of protopanaxadiol were(87.99±1.29)%and(14.86±0.25)%,respectively.[Conclusions]The 20(S)-PPD-PLGA-NPs were successfully prepared by emulsion solvent evaporation method,and the 20(S)-PPD-PLGA-NPs had good stability,to lay a foundation for the study of 20(S)-PPD-PLGA-NPs in vitro and in vivo.

Role of Polyethylene Glycol and Silica for Dissolution Enhancement of Cefuroxime Axetil: In-Vitro Performance Evaluation and Characterization

Cefuroxime Axetil (CA) a widely used cephalosporin antibiotic displays low aqueous solubility and high membrane penetrability. This results in its solubility driven variable and/or low oral bioavailability and therapeutic efficacy as a major drawback. Thus, most of the goal of our study was to increase the solubility as well as dissolution rate of CA using the simple and cost-effective solid dispersion (SD) method. At first, the SD formulations of CA were prepared at various weight ratios of Carplex-67 and PEG-4000 by solvent evaporation technique. These new formulations were then subjected to an in-vitro drug release performance study and tested for physicochemical characterization to distinguish the thermal behavior, crystallinity, interactions phenomena, and surface morphology. Among the formulated Cefuroxime Axetil Solid Dispersion (CSD), CSD-8 which contained CA, Carplex-67, and PEG-4000 at the weight ratio 1:3:2, respectively showed the most significant (p in-vitro dissolution in water, Gastric Simulated Fluid (GSF), and Intestinal Simulated Fluid (ISF). This study also showed a significant (p < 0.001) increase in drug release compared to the marketed product. Therefore, it is supposed to be a promising alternative to conventional antimicrobial therapy.

Development,characterization and solubility enhancement of comparative dissolution study of second generation of solid dispersions and microspheres for poorly water soluble drug

The poor dissolution characteristics of water-insoluble drugs are a major challenge for pharmaceutical scientists.Reduction of the particle size/increase in the surface area of the drug is a widely used and relatively simple method for increasing dissolution rates.The objective of this study was to improve solubility,release and comparability of dissolution of a poorly soluble drug using two different types of formulations(solid dispersions and microspheres).Hydrochlorothiazide was used as a model drug.The solid dispersions and microspheres were prepared by solvent evaporation method using ethyl cellulose,hydroxypropyl methylcellulose in different drug-to-carrier ratios(1:1,1:2 w:w).The prepared formulations were evaluated for interaction study by Fourier transform infrared spectroscopy,differential scanning calorimetry,percentage of practical yield,drug loading,surface morphology by scanning electron microscopy,optical microscopy and in-vitro release studies.The results showed no interaction between the drug and polymer,amorphous state of solid dispersions and microspheres,percentage yield of 42.53%to 78.10%,drug content of 99.60%to 99.64%,good spherical appearance in formulation VI and significant increase in the dissolution rate.

Formulation,characterization and in vivo and in vitro evaluation of aloe-emodin-loaded solid dispersions for dissolution enhancement

OBJECTIVE:To prepare aloe-emodin solid dispersion(AE-SD)and determine the metabolic process of AE and AE-SD in vivo.METHODS:AE-SD was prepared via solvent evaporation or solvent melting using PEG-6000 and PVP-K30 as carriers.Thermogravimetric analysis,X-ray diffraction spectroscopy,differential scanning calorimetry,Fourier transform infrared spectroscopy and scanning electron microscopy were used to identify the physical state of AESD.Optimal prescriptions were screened via the dissolution degree determination method.Using Phoenix software,AE suspension and AE-SD were subjected to a pharmacokinetic comparison study analyzing the alteration of behavior in vivo after AE was prepared as a solid dispersion.Acute toxicity was assessed in mice,and the physiological toxicity was used as the determination criterion for toxicity.RESULTS:AE-SD showed that AE existed in the carrier in an amorphous state.Compared with polyethylene glycol,polyvinylpyrrolidone(PVP)inhibited AE crystallization,causing the drug to transform from a dense crystalline state to an amorphous form and increasing the degree of drug dispersion.Therefore,it was more suitable as a carrier material for AE-SD.The addition of poloxamer(POL)was more beneficial to the stability of solid dispersions and could reduce the amount of PVP.The dissolution test confirmed that the optimal ratio of AE to the composite vector AE-PVP-POL was 1:2:2,and its dissolution effect was also optimal.Based on the pharmacokinetic comparison,the drug absorption was faster and quickly reached the peak of blood drug concentration in AE-SD compared to AE,the Cmax of AE-SD was greater than that of AE,and t1/2 and mean residence time of AE-SD were less than AE.The results showed that the drug metabolism in AE-SD was better,and the residence time was shorter.The toxicology study showed that both AE and AE-SD had no toxicity.CONCLUSION:This paper established that the solubility of the drug could be increased after preparing a solid dispersion,as demonstrated by in vitro dissolution experiments.In vivo pharmacokinetics studies confirmed that AE-SD could improve the bioavailability of AE in vivo,providing a new concept for the research and development of AE preparations.

Pharmaceutical amorphous solid dispersion: A review of manufacturing strategies

Amorphous solid dispersions(ASDs)are popular for enhancing the solubility and bioavailability of poorly water-soluble drugs.Various approaches have been employed to produce ASDs and novel techniques are emerging.This review provides an updated overview of manufacturing techniques for preparing ASDs.As physical stability is a critical quality attribute for ASD,the impact of formulation,equipment,and process variables,together with the downstream processing on physical stability of ASDs have been discussed.Selection strategies are proposed to identify suitable manufacturing methods,which may aid in the development of ASDs with satisfactory physical stability.

Ultralow friction polymer composites incorporated with mono-dispersed oil microcapsules

Ultralow friction polymer composites were prepared by adding oil-loaded microcapsules into epoxy(EP)resin.Mono-dispersed polystyrene(PS)/poly alpha olefin(PAO)microcapsules with a diameter of~2μm and a shell thickness of~30 nm were prepared by solvent evaporation method in an oil-in-water emulsion.The lubrication behaviors of the EP resin composites with oil-loaded microcapsules have been investigated under different loads and sliding speeds.As compared with the pure EP resin,the friction coefficient of the composite could be reduced to 4%(from 0.71 to 0.028)and the wear rate could be decreased up to two orders of magnitude.It was demonstrated that the released PAO oil from the microcapsules during the friction process produced a boundary lubricating film,which could prevent the direct contact of two rubbing surfaces,and thus leading to an extremely low friction coefficient and wear rate.Moreover,the composites with microcapsules could achieve comparable lubrication properties to the case under the external lubrication condition,while the former case could effectively minimize the lubricant leakage and improve the lubrication efficiency.

Preparation and characterization of biomimetic adsorbent from poly-3-hydroxybutyrate

Biomimetic adsorbent named as PHBBMA was prepared from lipophilic poly-3-hydroxybutyrate （PHB） by a modified double emulsion solvent evaporation method. PHBBMA, characterized by using scanning electron microscope and nitrogen adsorption/desorption measurements, is porous spherical particles. The characterization with the thermal gravimetric analysis and differential scanning calorimetry, 1 H nuclear magnetic resonance and Fourier transform infrared spectroscopy showed that PHBBMA preparation was a physical process without chemical reaction. The adsorption of PHBBMA for o-nitrochlorobenzene （o-NCB） was fitted better by Langmuir model than by Freundlich model, while the pseudo second-order model fitting was better than the pseudo first-order model fitting. The maximal adsorption capacity of PHBBMA for o-NCB was 57.83 mg/g at 30°C, although its specific surface area （S BET ） was only 8.45 m 2 /g. PHBBMA is a safe and environmental friendly adsorbent with high adsorption capacity because its component is innocuous and biodegradable PHB produced reusing wastes and contaminants, no byproduct can produced, and its ester and hydrocarbyl groups have strong affinity with organochlorine compounds. The further work will focus on the modification and improvement of PHBBMA in order to increase its S BET and adsorption capacity.

Optimization of Jiawei Qing'e Oral Fast Disintegrating Tablets Based on Response Surface-Central Composite Design

Abstract: Objective To apply the response surface-central composite design to developing and optimizing the oral fastdisintegrating tablets (ODT) formulation for Jiawei Qing’e, a kind of prescription of Chinese herbal medicine.Methods The bitterness of Jiawei Qing’e was masked using Eudragit E-100 by solvent evaporation technique.Response surface approach was applied to investigating the interaction of formulation parameters in optimizing theformulation. The independent variables were Eudragit E-100/drug ratio (X1), amount of disintegrants (X2), and theamount of diluents (X3). The disintegration time (Y1), hardness (Y2), and weight variations of the tablets werecharacterized. Results The models predicted levels of X1= 4.63%, X2= 5.25%, and X3= 34.33%, for the optimalformulation having a hardness of 3.0 kg with the disintegration time of 30 s within experimental region. The observedresponse of Y1= 26.5 s and Y2= 3.14 kg reasonably agreed with the predicted response. Conclusion Responsesurface methodology shows the good predictability and reliability in optimizing the formulation. The optimized ODTof Jiawei Qing’e has acceptable taste, rapid disintegrating ability, and good mechanical strength.

Paclitaxel formulation with stable sustained-release behavior and its biological safety evaluation

Biological safety and stable sustained-release of the drug are two crucial issues involved in the formulation of paclitaxel.Focusing on these issues, by using the FDA approved polylactide as carrier material, soybean lecithin as surfactant and maltodextrin as thickener, paclitaxel loaded PLA microspheres were simply prepared by solvent evaporation, thus guaranteeing the biological safety. The introduction of maltodextrin as a thickener aided to a stable sustained-release of paclitaxel. Surface morphology, particle size, drug loading rate, encapsulation efficiency and in vitro drug release behavior were investigated.Biological safety evaluations such as acute toxicity, allergies, hemolysis, skin stimulation and genotoxicity test were also carried out. Results showed that the obtained microspheres were biocompatible and could release paclitaxel at a desirable constant rate.Therefore, the simply prepared paclitaxel formulation with good biological safety and desirable release behavior exhibited great potential of local injection of paclitaxel for the clinical use in the future.

Deep insight into the charge transfer interactions in 1,2,4,5-tetracyanobenzene-phenazine cocrystal

A new charge transfer cocrystal of 1,2,4,5-tetracyanobenzene(TCNB)-phenazine(PTC)was prepared by solvent evaporation method.The donor and acceptor molecules of cocrystal are stacked face to face with a mixed-stacking,implying a strong charge transfer(CT)interactions in the cocrystal system.The spectroscopic studies,single-crystal X-ray diffraction structure,density functional theory(DFT)and Hirschfield surfaces calculations are carried out to explore the relationship between structure and properties of cocrystal system,which show that the intermolecular interactions in PTC are stronger than those of single components,leading to the stability and photophysical behaviors of cocrystal different from their constitute units.This study will be helpful for the design and preparation of multifunctional cocrystal materials.

Red-blood-cell-shaped chitosan microparticles prepared by electrospraying

Red-blood-cell-shaped chitosan microparticles with acid-triggered dissolution and auto-fluorescence were successfully fabricated by a simple strategy combining electrospraying with a solvent diffusion process controlled by solvent evaporation. The sizes of the prepared chitosan microparticles were rela- tively uniform. Control of the solvent diffusion process was crucial for the formation of microparticles with concave morphology. A chitosan aqueous solution containing 20vo1% ethanol as the evaporable solvent and 30 vol% dimethyl sulfoxide as the diffusible solvent was optimal for preparation of chitosan microparticles with the desired red-blood-cell-like size and shape. These chitosan microparticles will be highly attractive for many biological and biomedical aoolications.

Formation of biomimetic hierarchical nanostructure in homopolymers and block copolymer ternary blend particles

In order to mimic hierarchical nanostructures in nature,particles of polymer blends consisting of poly(4-butyltriphenylamine)(PBTPA),poly(methyl methacrylate)(PMMA)and PBTPA-block-PMMA were fabricated by a solvent evaporation method.Effects of the molecular weight and the chemical composition of PBTPA-b-PMMA,molecular weights of homopolymers,and the composition of the blend on the morphology were investigated.The polymer blend particle consisting of PBTPA and PMMA homopolymers exhibited thermodynamically favored core-shell structure,in which more hydrophilic PMMA-shell surrounded PBTPA-core.The addition of 10 wt%of PBTPA-b-PMMA caused the morphological transition from core-shell toJanus or inversed core-shell,in which PBTPA-shell surrounded PMMA-core,depending on the molecular weight of PBTPA segment in PBTPA-b-PMMA.When the molecular weight of PMMA segment was higher than that of PMMA homopolymer,watermelon-like particles in which small PBTPA domain less than 80 nm dispersed in the PMMA domain surrounded by PBTPA shell were observed.As the ratio of PBTPA-b-PMMA increased,the interface of the macrophase separation became obscure.At 50 wt%of the PBTPA-b-PMMA,only microphase separation was observed.The measurement of interfacial tension by pendant drop method demonstrated that PBTPA-b-PMMA lower the interfacial tension between PBTPA and the aqueous phase to the value similar to that of PMMA with the aqueous phase.