Antisolvent Research Articles

Precise Control of Crystal Growth for Highly Efficient CsPbI2Br Perovskite Solar Cells

Summary All-inorganic perovskite solar cells (pero-SCs) are attracting considerable attention due to their promising thermal stability, but their inferior power-conversion efficiency (PCE) and moisture instability are hindering their application. Here, we used a gradient thermal annealing (GTA) method to control the growth of α-CsPbI2Br crystals and then utilized a green anti-solvent (ATS) isopropanol to further optimize the morphology of α-CsPbI2Br film. Through this GTA-ATS synergetic effect, the growth of α-CsPbI2Br crystals could be precisely controlled, leading to a high-quality perovskite film with one-micron average grain size, low root-mean-square of 25.9 nm, and reduced defect density. Pero-SCs based on this CsPbI2Br film achieved a champion scan PCE of 16.07% (stabilized efficiency of 15.75%), which is the highest efficiency reported in all-inorganic pero-SCs. Moreover, the CsPbI2Br pero-SC demonstrates excellent robustness against moisture and oxygen, and maintains 90% of initial PCE after aging 120 hr under 100 mW/cm2 UV irradiation.

Adamantanes Enhance the Photovoltaic Performance and Operational Stability of Perovskite Solar Cells by Effective Mitigation of Interfacial Defect States

AbstractPassivation of electronic defects is an effective strategy to boost the performance and operational stability of perovskite solar cells (PSCs). Identifying molecular materials that achieve this purpose is a key target of current research efforts. Here, adamantane (AD) and 1‐adamantylamine (ADA) are introduced as molecular modulators to abate electronic defects present within the bulk and at the perovskite–hole conductor interface. To this effect, the modulator is added either into the antisolvent (AS) to precipitate it together with the perovskite (AS method) or they are spin coated (SC) onto its surface (SC method). Time‐resolved photoluminescence measurements show substantially longer lifetimes for perovskite films treated with AD and ADA compared to the reference sample. In line with this observation, it is found that the presence of AD and ADA molecules at the interface between the perovskite film and the hole conductor increases all photovoltaic metrics, in particular the open circuit photovoltage (V oc) as well as the operational stability of the PSC.

Simultaneous micronization and purification of bioactive fraction by supercritical antisolvent technology.

Simultaneous micronization and purification of DLBS3233 bioactive fraction, a combination of two Indonesian herbals Lagerstroemia speciosa and Cinnamomum burmannii has been successfully performed via supercritical anti-solvent (SAS) technology. The objective of the present study was to investigate the effectiveness of SAS technology to micronize and reduce coumarin content of DLBS3233. The effects of four SAS process parameters, i.e. pressure, temperature, concentration and solution flow rate on particle formation were investigated. In SAS process, DLBS3233 was dissolved in dimethylformamide (DMF) as the liquid solvent. The solution was then pumped through a nozzle into a chamber simultaneously with supercritical carbon dioxide (SC-CO2) which acts as the anti-solvent, resulting in DLBS3233 precipitation. Physicochemical properties of unprocessed DLBS3233 and SAS-processed DLBS3233 particles were analyzed using scanning electron microscopy (SEM) and high pressure liquid chromatography (HPLC). Total polyphenol content (TPC) was also analyzed. Particles with mean particle size ranging from 0.107±0.028 μm to 0.298±0.138 μm were obtained by varying the process parameters. SAS-processed DLBS3233 particles showed no coumarin content in all experiments studied in this work. Results of TPC analysis revealed no significant change in SAS-processed DLBS3233 particles compared to unprocessed DLBS3233. Nano-sized DLBS3233 particles with no coumarin content have been successfully produced using SAS process. This study demonstrates the ability of SAS for processing herbal medicine in single step process.

Quercetin nanoparticles attenuates scopolamine induced spatial memory deficits and pathological damages in rats

Quercetin is a well-known flavonoid, has low bioavailability. Quercetin nanoparticles (NQC) enhance its bioavailability. NQC were not explored for their potential therapeutic activities in Alzheimer’s disease (AD). Hence, the present study was performed to evaluate the protective effect of NQC in comparison to free quercetin against scopolamine induced spatial memory impairments.NQC prepared by anti solvent precipitation method. Quercetin, NQC (30mg/kg p.o.) and rivastigmine (2mg/kg i.p.) as a reference drug were administered for 8 consecutive days. At the end of the treatment period memory impairments were induced by a single injection of scopolamine (20mg/kg; i.p.). Conditioned avoidance and rectangular-maze tests were conducted 30min thereafter then rats were sacrificed and brain homogenates were used for the estimation of glutathione (GSH), catalase and malondialdehyde (MDA) contents together with acetyl cholinesterase (AchE) activity. In addition, histopathologic studies were also performed.The size of NQC was observed below 300nm. NQC significantly reduced the transfer latency and conditioned avoidance response compared to scopolamine treated group (p<0.05). Pretreatment with NQC showed a significant (p<0.05) decrease in MDA, AchE levels and increase in brain catalase and GSH levels to be similar to that observed in the rivastigmine group.In all the behavioral, biochemical and histological experiments, the rats treated with NQC showed additional distinguished results compared to quercetin group indicating that a preventive strategy against the progression of AD. This approach of quercetin nanoparticles provides the potential therapeutic application in human neurodegenerative disease in future.

A novel method for food particle production using subcritical water extraction: Ganoderma mushroom as a case example

In recent years, supercritical fluid-based technologies have been used for the production of food particles as well as the extraction. These methods are used in particle generation as well as extraction due to properties of solvent such as having good dissolving and diffusing power, moderable conditions, capability to produce particles with a regular particle size distribution of the solvent and being environmentally friendly. Recently, three different techniques named rapid expansion of supercritical fluid (RESS), supercritical anti solvent application (SAS) and particle formation with gas-saturated solvent (PGSS) are used for particle generation. In this study, a novel system capable of doing subcritical water extraction and particle formation was briefly introduced. The system was based on first hydrothermal extraction of target compound, then transition of saturated extract solution into fine particles at underflow in hot air assistance. Ganoderma lucidum mushroom was used as working material to investigate process parameters. Also, extract composition and structure were identified.

Investigation of Formulation and Process Parameters for the Production of Esomeprazole Nanosuspension by Anti Solvent Precipitation Ultasonication Technique

Investigation of Formulation and Process Parameters for the Production of Esomeprazole Nanosuspension by Anti Solvent Precipitation Ultasonication Technique

A deterministic formulation and on-line monitoring technique for the measurement of salt concentration in non-isothermal antisolvent crystallization processes

A deterministic formulation and on-line monitoring technique for the measurement of salt concentration in non-isothermal antisolvent crystallization processes

Control of powders morphology in the supercritical antisolvent technique using solvent mixtures

Control of powders morphology in the supercritical antisolvent technique using solvent mixtures

Preparation, Characterization and Function Evaluation of Ultrafine Resveratrol Powder

By supercritical SAS,we made the resveratrol anti solvent recrystallization to prepare ultrafine resveratrol powder under supercritical condition. The conditions were under 50℃,20 MPa,resveratrol ethanol solution concentration of 9 mg · m L- 1,and sample solution flow rate of 1 m L · min- 1. We analyzed the particles by Dynamic Light Scattering( DLS) equipment and Scanning Electron Microscopy( SEM). The particle size of the particles was greatly reduced and the average particle size was 0. 68 ± 0. 03 μm. In addition,characterization of ultrafine Res and raw-resveratrol were tested by Fourier transform infrared spectroscopy( FTIR),X-ray diffraction( XRD),High performance liquid chromatography( HPLC) and Liquid chromatographymass spectrometry( LC-MS). SAS process didn't change the chemical structure of Res. The chemical structure of resveratrol was unaffected by the SAS process. The degree of crystallinity of the u-Res particles greatly reduced. We used the purity of the u-Res particles increased from 98. 5% to 99. 2% during the SAS process.Using drosophila anti-aging experiments to detect the oxidation resistance of resveratrol. The antioxidant capacity of resveratrol powder were higher than that in the second-stage and blank experiment under the concentration of resveratrol solution,2. 5,5 and 10 mg · m L- 1. The resveratrol had the oxidation resistance,and ultrafine resveratrol powder was better than raw-resveratrol powder.

Laccase immobilization on radiation synthesized epoxy functionalized polyethersulfone beads and their application for degradation of acid dye

The enzymatic degradation of textile dyes offers an alternative approach over the conventional waste water treatment processes. Covalent immobilization of the enzymes onto insoluble supports not only permits their reusability and easy separation of enzymes from the product but also, if properly performed, may improve their activities, stability and hence reduces the cost of process. In the present work, epoxy functionalized polyethersulfone (PES) was synthesized via radiation induced polymerization of poly(2,3-epoxypropyl methacrylate) [poly(EPMA)] in PES-NMP (N-methyl-2-pyrrolidone) solution using 60Co-gamma radiation source. Poly(EPMA)-functionalized-PES [poly(EPMA)-f-PES] beads were fabricated via phase inversion route using water as the anti solvent. Laccase was covalently immobilized on to the beads via one step-room temperature coupling reaction of amine group of enzyme with the epoxy group of poly(EPMA). Enzyme activity was assayed using 2,2′-azino-bis(3-ethylthiazoline-6-sulfonate) (ABTS) as the substrate. Effect of temperature and pH on the free and immobilized enzyme activity was studied. The immobilized laccase was successfully employed to degrade Acid Red 1 (AR1) dye in aqueous solution. Room temperature incubation of the laccase immobilized poly(EPMA)-f-PES beads with AR1 dye (∼10 ppm) resulted in ∼88% degradation of the dye over a period of 15 days.

Preparation and Properties of Submicrometer‐Sized LLM‐105 via Spray‐Crystallization Method

AbstractSubmicrometer‐sized 2,6‐diamino‐3,5‐dinitropyrazine‐1‐oxide (LLM‐105) crystals were prepared by spray‐crystallization method with dimethyl sulfoxide (DMSO) and ultra‐pure water with surfactant as the solvent and anti solvent, respectively. Submicrometer‐sized LLM‐105 particles were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), and particle size analysis. The thermal stability and sensitivity properties of submicrometer‐sized LLM‐105 were also investigated. The results revealed that the submicrometer‐sized LLM‐105 particles are spherelike in morphology with a narrow particle size distribution at the range of 100–600 nm. The submicrometer‐sized LLM‐105 has a lower exothermic peak at about 343.7 °C compared with the synthesized material. Sensitivity tests showed that submicrometer‐sized LLM‐105 is more insensitive under impact stimulus with a drop height (H50) of 102 cm. The submicrometer‐sized LLM‐105‐based PBX is more sensitive for short impulse shock wave that can be initiated at lower initiation current.

Surface Energy Evolution in Pharmaceutical Powder Micronization Using Compressed Gas Antisolvent (Re-)Precipitation

We illustrate the importance of environment-dependent surface energy changes in predicting the micronization of active pharmaceutical ingredients (APIs) in gas antisolvent precipitation (GASP) processes. This size-reduction scheme exploits compressed CO2(g) as antisolvent (AS) at near-ambient temperatures. Ordinary API-loaded solvents (often sprays) are contacted with dense CO2, and during CO2 uptake in an evolving expanding liquid API + solvent + CO2 solution droplet, particle nucleation (N) sets in, continuing along with growth (G) and, ultimately, coagulation. A rational method [due to Nielsen and Sohnel (J. Cryst. Growth 1971, 11, 233) and Mersmann (J. Cryst. Growth 1990, 102, 841)) is used to estimate the changing embryonic solid/ternary solution interfacial energy, γ. We demonstrate the dramatic yield and crystal size distribution (CSD) consequences of surface energy evolution (SEE) by carrying out N/G calculations for the surrogate organic API: phenanthrene dissolved in representative well-mixed micrometer-sized toluene droplets (sprayed into 298 K CO2 for p < 60 bar). To solve the population balance partial differential equation, we exploit the method of characteristics. Our results demonstrate that assuming constant surface energy, sometimes reasonable for API precipitation via the rapid expansion of supercritical-CO2 solvent (i.e.: relatively dilute rapid expansion of a supercritical solution conditions), fails for GASP-process modeling. When the crystal growth kinetics are sufficiently rapid, SEE also modifies performance via the Gibbs–Kelvin reduction of small particle growth rates. Rational yet tractable methods to incorporate both systematic effects in future design/optimization/parameter estimation calculations are suggested.

Application of Ultrasonic Atomization for Biopolymer Particles and Tube Fabrication

This research aimed to study the potential use of ultrasonic atomization technique for biopolymer particles and tube preparation. Poly(lactic acid) (PLA) was selected as a model polymer. The polymer solutions were, first prepared. For particles forming, the factors affecting the preparation such as the polymer concentrations, the distance between a nozzle and a target plates and the feed flowrate target plate were investigated. In case of tube fabrication, the feed flowrate and the time of atomizing were of interest. All samples were analyzed for particle sizes and SEM images. For particles preparation, it was found that when increasing concentrations of PLA, the particles size of PLA increased as a result of the increased viscosity of polymer solution, causing larger droplets of spray, hence large particles formed. Upon varying the distance between a nozzle and a target plate, it was found that the spray distance did not affect the particle sizes. For tube fabrication, the polymer solution was atomized over the rotating shaft. The results showed the rotating shaft speed had no effects on the tube structure. The tubes could be successfully formed. The tube had rough surface without holes. When increasing the atomizing, the tube had rougher surface. To create porous structure of the tube, anti solvent was added to the polymer solution prior to spraying. The as-sprayed tube illustrated rough surface with network structures having porous-like scaffold structure due to the different evaporation rate between solvent and anti-solvent

Investigation of Formulation and Process Parameters for the Production of Esomeprazole Nanosuspension by Anti Solvent Precipitation Ultasonication Technique

Investigation of Formulation and Process Parameters for the Production of Esomeprazole Nanosuspension by Anti Solvent Precipitation Ultasonication Technique

Naproxen–nicotinamide cocrystals produced by CO2 antisolvent

Cocrystals of naproxen (NPX) and nicotinamide (NCTA) were successfully prepared in acetone using CO2 as antisolvent in the so-called GAS technique (Gaseous Anti Solvent). Infra-red spectroscopy and powder X-ray analysis evidenced the same hydrogen-bond network and stoichiometry than cocrystals produced by cooling crystallization, i.e. 2 NPX for 1 NCTA, which coincided with literature results as well. The purity of powders in cocrystals was evaluated thanks to chromatography analysis and the homocrystals identification by powder X-rays diffraction. The effect of initial mixture composition (NPX:NCTA ratio) and of CO2 and acetone mixing conditions (CO2 introduction rate, stirring speed) was investigated. Results showed that the cocrystal purity was closed to 98±2% whatever the initial ratio in solution of 3:1, 2:1, 1:1 but levelled down to 67% when a 1:2 solution was processed. The mixing conditions did not influence the cocrystal stoichiometry or purity (experiments carried out from a 2:1 mixture) but impacted on precipitation yield and size distribution. In best conditions, 62% of the initial processed amount was collected in the vessel as a powder of sizes below 180μm made at 98% of NPX2:NCTA1 cocrystals.

Image-based multi-resolution-ANN approach for on-line particle size characterization

An image-based multi-resolution sensor for online prediction of crystal size distribution (CSD) is proposed. The mean and standard deviation (std) of lognormal probability density function as the CSD can be predicted through the on-line sensor. Texture analysis, through wavelet-texture algorithm, as characteristic parameters to follow the crystal growth is utilized. Following nonlinear mappings consisting of artificial neural networks (ANNs) is incorporated using as inputs the texture information in conjunction with the available on-line process conditions. The output data for training the ANN models are measured manually at different sampling times as well as in a range of operating conditions. Validations against experimental data are presented for the NaCl-water-ethanol anti-solvent crystallization system.

Preparation and Characterization of Micronized Vitexin by Antisolvent Recrystallization Method

To improve the dissolution rate of vitexin,the micronization of vitexin in an antisolvent recrystallization process using N-methylpyrrolidone(NMP) as solvent and water as antisolvent was studied in this paper.The effects of operating parameters including concentrations of vitexin solution,system temperatures,stirring rates and kinds of surfactants(PVP,Tween80,SDS) on the particle size of micronized vitexin were investigated.Particles of micronized vitexin with a mean particle size of 291.1 nm were obtained under the optimized process conditions(vitexin solution concentration 20 mg·mL-1,volume ratio of antisolvent to solvent 10∶ 1,stirring rate 1 500 r·min-1 and concentration of PVP 8 mg·mL-1).The processed vitexin particles and the unprocessed one were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),differential scanning calorimetry(DSC),Fourier-transform infrared spectroscopy(FT-IR).The results showed that antisolvent recrystallization process did not induce degradation of vitexin and the micronized vitexin had lower crystallinity.The chemical properties of the processed vitexin did not change when compared with the original drug,and there was a significant increase of the dissolution rate of the processed vitexin comparing with the unprocessed vitexin.

Pressurized Organic Solvent Extraction with On-line Particle Formation by Supercritical Anti Solvent Processes

In this work, anovel on-line process for pressurised hot organic solvent extraction of antio xidants from plantsas well as precip itation of the extract with or without a carrier material in one step was developed. This process has been called OEPO,Organic solvent Ext raction and On-line particle formation. With this process, different products with a very low residual organic solvent concentration (< 50 ppm) can be obtained by the use of supercritical CO2 as anti solvent for solvent elimination.OEPO process consists of hyphenated Pressurized Liquid Extraction (PLE)-Supercritical Anti So lvent (SAS) precipitation, PLE-SAS co-p recipitat ion and PLE-Supercritical Fluid Ext raction of Emulsions (SFEE). OEPO process was successfully developed using Brazilian g inseng roots (Pfa ffiaglomerata)as a model case using ethyl acetate as extracting solvent. Results were co mpared, in terms of antio xidant activity o r mo rphology, with the ones obtained by each process separately.In addition, an optimizat ion study for antio xidants recovery was performed using ethyl acetate as extracting solvent during PLE process. Optimu m PLE extracts were produced under moderate extraction temperature (373 K) and high static extraction t ime (15 min). Under this condition an ext raction yield o f 1% (d ry basis, d.b.) and an antioxidant activity of 53% are obtained, wh ich was appro ximately 14% higherthan that observed after PLE-SAS p recipitation and after SAS precipitation performed in two steps (step one - PLE ext raction; step two - SAS precipitation by the use of the ext ract solution produced by step one stored).Similar behavior (hyphenated process producing similar p roducts than the two step process done separately) was observed for PLE-SAS co-precip itation and PLE-SFEE indicating that the OEPO process developed in this work can be considered as a suitable and p ro mising process to obtain, in only one step, different products (precipitated extract, co-precipitated extract or encapsulated extract in suspension), direct ly fro m plant materials.

Application of Plackett–Burman screening design for preparing glibenclamide nanoparticles for dissolution enhancement

This study is to improve the dissolution characteristics of a poorly water-soluble drug glibenclamide (GLB), by preparing nanoparticles through liquid anti solvent precipitation. A Plackett–Burman screening design was employed to screen the significant formulation and process variables. A total of 12 experiments were generated by Minitab® 16 for screening 5 independent variables namely the amount of poloxamer 188 (PX) (X1), amount of PVP S 630 D (PD) (X2), solvent to antisolvent volume ratio (S/AS) (X3), amount of GLB (X4) and speed of mixing (X5). Mean particle size (Y1), saturation solubility (Y2) and % dissolution efficiency (%DE 5min ) (Y3) were selected as response variables. All the regression models yielded a good fit with high determination coefficient and F value. The Pareto chart depicted that all the independent variables except the amount of GLB had a significant effect (p < 0.001) on the response variables. The mathematical model for mean particle size (PS) generated from the regression analysis was given by PS = 830 − 8.14 PX + 12.8 PD − 11.1 S/AS + 1.42 GLB Conc. − 0.676 speed of mixing (R 2 = 93.5, F ratio = 17.28, p < 0.001). Prepared GLB nanoparticles exemplified a significant improvement (p < 0.05) in the release as compared to pure GLB with the optimum formulation releasing almost 80% drug within first 5 min. The X-ray diffraction studies concluded that the crystallinity of nanoparticles from the optimum batch was intact and the increased dissolution could be ascribed to conversion of unmilled GLB to nanoparticles. Plackett-Burman screening design was applied to prepare glibenclamide nanoparticles to improve its dissolution characteristics. Pareto chart revealed that all the predetermined independent variables except drug concentration had a significant effect on the dependent variables. The optimum batch of nanoparticles showed a mean particle size of 279 nm and released almost 80 % drug within first 5 min which is significantly ( p < 0.001 ) higher as compared to pure drug which showed 8.5 % dissolution. ► Glibenclamide nanoparticles have been prepared using liquid anti solvent precipitation. ► Formulation and process variables were screened by Plackett–Burman screening design. ► Optimum formulation had crystalline drug and released 80% drug within 5 min. ► Plackett–Burman screening design helped in understanding the mechanics of process. ► The improved dissolution of glibenclamide might improve patient compliance.

Hyperconjugation-Mediated Solvent Effects in Phosphoanhydride Bonds

Density functional theory and natural bond orbital analysis are used to explore the impact of solvent on hyperconjugation in methyl triphosphate, a model for "energy rich" phosphoanhydride bonds, such as found in ATP. As expected, dihedral rotation of a hydroxyl group vicinal to the phosphoanhydride bond reveals that the conformational dependence of the anomeric effect involves modulation of the orbital overlap between the donor and acceptor orbitals. However, a conformational independence was observed in the rotation of a solvent hydrogen bond. As one lone pair orbital rotates away from an optimal antiperiplanar orientation, the overall magnitude of the anomeric effect is compensated approximately by the other lone pair as it becomes more antiperiplanar. Furthermore, solvent modulation of the anomeric effect is not restricted to the antiperiplanar lone pair; hydrogen bonds involving gauche lone pairs also affect the anomeric interaction and the strength of the phosphoanhydride bond. Both gauche and anti solvent hydrogen bonds lengthen nonbridging O-P bonds, increasing the distance between donor and acceptor orbitals and decreasing orbital overlap, which leads to a reduction of the anomeric effect. Solvent effects are additive with greater reduction in the anomeric effect upon increasing water coordination. By controlling the coordination environment of substrates in an active site, kinases, phosphatases, and other enzymes important in metabolism and signaling may have the potential to modulate the stability of individual phosphoanhydride bonds through stereoelectronic effects.