Solvent Isotherms and Structural Transitions in Nanoparticle Superlattice Assembly.

We introduce a Molecular Theory for Compressible Fluids (MOLT-CF) that enables us to compute free energies and other thermodynamic functions for nanoparticle superlattices with any solvent content, including the dry limit. Quantitative agreement is observed between MOLT-CF and united-atom molecular dynamics simulations performed to assess the reliability and precision of the theory. Among other predictions, MOLT-CF shows that the amount of solvent within the superlattice decreases approximately linearly with its vapor pressure and that in the late stages of drying, solvent-filled voids form at lattice interstitials. Applied to single-component superlattices, MOLT-CF predicts fcc-to-bcc Bain transitions for decreasing vapor pressure and for increasing ligand length, both in agreement with experimental results. We explore the stability of other single-component phases and show that the C14 Frank-Kasper phase, which has been reported in experiments, is not a global free-energy minimum. Implications for precise assembly and prediction of multicomponent nanoparticle systems are discussed.

Magnetic Polystyrene Nanoparticles Prepared by Emulsion Solvent-Evaporation for the Chemiluminescent Immunoassay.

In clinical diagnosis, magnetic polystyrene nanoparticles (MPS NPs) are commonly applied to, e.g., the chemiluminescent immunoassay (CLEIA). However, the conventional preparation method of MPS NPs requires a long duration of heating to form polymer particles, which is inefficient. In this study, we prepared MPS NPs by emulsion solvent-evaporation without heating. We evaluated the effect of the solvent in the water and organic phases on the magnetic particle content. MPS NPs prepared by 4% (v/v) MeOH aqueous solution and adding stearic acid (SA) (4MeSA-MPS NPs) exhibited the highest magnetic particle content. Furthermore, CLEIA analysis indicates that the C-reactive protein detection limit is 80 pg/mL. Thus, 4MeSA-MPS NPs are promising for clinical diagnoses.

Effect of stoichiometry upon the characteristics of quercetin-arginine cocrystals formulated through solution crystallization.

OBJECTIVE: The aim of this study is to demonstrate the effect of stoichiometry upon characteristics of quercetin-arginine (QCT-Arg) cocrystals. SIGNIFICANCE: Quercetin (QCT) is a most abundant flavonoid in vegetables and fruits and has been widely used as an antioxidant. However, its oral bioavailability remains low due to poor aqueous solubility. We illustrate that QCT-Arg cocrystals formulated through an optimized stoichiometry can be a useful approach for its solubilization. METHOD: Cocrystals were prepared using solvent evaporation method. Characterizations were performed through microscopic, spectroscopic, and thermal techniques. The stoichiometry was confirmed from the binary phase diagram which was prepared using thermograms derived from differential scanning calorimetric experiments. RESULT: Cocrystal formation was accompanied by the conversion of isotropic phase into anisotropic one. Thread-like cocrystals were formed, regardless of QCT-Arg stoichiometry and solvent's polarity. Spectral analyses suggested that cocrystal structure was held together by hydrogen bonding between QCT and Arg. We ruled out the existence of eutectic mixture based on the observation of two eutectic points in the binary phase diagram. CONCLUSION: Morphology of cocrystals remained unaffected by the solvent type, stoichiometry and the presence of surfactant. We noticed that the cocrystals could improve the aqueous solubility of QCT.

Formulation and evaluation of Fluconazole Nanosuspensions: In vitro characterization and transcorneal permeability studies.

The aim in this study was to develop and evaluate a nanofluconazole (FLZ) formulation with increased solubility and permeation rate using nanosuspensions. The FLZ nanosuspensions were stabilized using a variety of stabilizing agents and surfactants in various concentrations. The FLZ nanosuspension was characterized in vitro using particle size, zeta potential, X-ray powder diffraction (XRPD), and solubility. In addition, the ex vivo ocular permeation of FLZ through a goat cornea was analyzed. The results showed that the particle size of all nanosuspension formulations was in the nanometer range from 174.5 ± 1.9 to 720.2 ± 4.77 nm; that of the untreated drug was 18.34 µm. The zeta potential values were acceptable, which indicated suitable stability for formulations. The solubility of the nanosuspensions was up to 5.7-fold higher compared with that of the untreated drug. The results of the ex vivo ocular diffusion of the FLZ nanosuspensions showed the percentage of FLZ penetrating via the goat cornea increased after using Kollicoat to stabilize the nanosuspension formulation. Consequently, when using a nanosuspension formulation of Kollicoat, the antifungal activity of the drug strengthens.

Sorafenib and Piperine co-loaded PLGA nanoparticles: Development, characterization, and anti-cancer activity against hepatocellular carcinoma cell line.

Hepatocellular carcinoma (HCC) exhibits high mortality rates in the advanced stage (>90 %). Sorafenib (SORA) is a targeted therapy approved for the treatment of advanced HCC; however, the reported response rate to such a therapeutic is suboptimal (<3%). Piperine (PIP) is an alkaloid demonstrated to exert a direct tumoricidal activity in HCC and improve the pharmacokinetic profiles of anticancer drugs including SORA. In this study, we developed a strategy to improve efficacy outcomes in HCC using PIP as an add-on treatment to support the first-line therapy SORA using biodegradable Poly (D, L-Lactide-co-glycolide, PLGA) nanoparticles (NPs). SORA and PIP (both exhibit low aqueous solubility) were co-loaded into PLGA NPs (PNPs) and stabilized with various concentrations of polyvinyl alcohol (PVA). The SORA and PIP-loaded PNPs (SP-PNPs) were characterized using Fourier Transform Infrared (FTIR) Spectroscopy, X-ray Powder Diffraction (XRD), Dynamic Light Scattering (DLS), and Scanning Electron Microscopy (SEM), Release of these drugs from SP-PNPs was investigated in vitro at both physiological and acidic pH, and kinetic models were employed to assess the mechanism of drug release. The in vitro efficacy of SP-PNPs against HCC cells (HepG2) was also evaluated. FTIR and XRD analyses revealed that the drugs encapsulated in PNPs were in an amorphous state, with no observed chemical interactions among the drugs or excipients. Assessment of drug release in vitro at pH 5 and 7.4 showed that SORA and PIP loaded in PNPs with 0.5 % PVA were released in a sustained manner, unlike pure drugs, which exhibited relatively fast release. SP-PNPs with 0.5 % PVA were spherical, had an average size of 224 nm, and had a high encapsulation efficiency (SORA âˆ¼ 82 %, PIP âˆ¼ 79 %), as well as superior cytotoxicity compared to SORA monotherapy in vitro. These results suggest that combining PIP with SORA using PNPs may be an effective strategy for the treatment of HCC and may set the stage for a comprehensive in vivo study to evaluate the efficacy and safety of this novel formulation using a murine HCC model.

Preparation of copolymer 7-hydroxyethyl chrysin loaded PLGA nanoparticles and the in vitro release. / 7-ç¾Ÿä¹™åŸºç™½æ¨ç´ èšä¹³é ¸-ç¾ŸåŸºä¹™é ¸å ±èšç‰©çº³ç±³ç²’çš„åˆ¶å¤‡åŠä½“å¤–é‡Šæ”¾è¯„ä»·.

OBJECTIVES: To prepare 7-hydroxyethyl chrysin (7-HEC) loaded poly (lactic-co-glycolic acid) (PLGA) nanoparticles and to detect the in vitro release. METHODS: The 7-HEC/PLGA nanoparticles were prepared by emulsification solvent volatilization method. The particle size, polydispersity index (PDI), encapsulation rate, drug loading and zeta potential were measured. The prescription was optimized by single factor investigation combined with Box-Behnken response surface method. Mannitol was used as protectant to prepare lyophilized powder, and the optimal formulation was characterized and studied for the in vitro release. RESULTS: The optimal formulation of 7-HEC/PLGA nanoparticles was as follows: drug loading ratio of 2.12∶20, oil-water volume ratio of 1∶14.7, and 2.72% soybean phospholipid as emulsifier. With the optimal formulation, the average particle size of 7-HEC/PLGA nanoparticles was (240.28±0.96) nm, the PDI was 0.25±0.69, the encapsulation rate was (75.74±0.80)%, the drug loading capacity was (6.98±0.83)%, and the potentiostatic potential was (－18.17±0.17) mV. The cumulative in vitro release reached more than 50% within 48 h. CONCLUSIONS: The optimized formulation is stable and easy to operate. The prepared 7-HEC/PLGA nanoparticles have uniform particle size, high encapsulation rate and significantly higher dissolution rate than 7-HEC.

Room-Temperature Solvent Evaporation Induced Crystallization: A General Strategy for Growth of Halide Perovskite Single Crystals by Applying the Le Chatelier's Principle.

The growth of high-quality halide perovskite single crystals is imperative to study their intrinsic physical properties and to realize high-performance optoelectronic devices. Here, a room-temperature solvent evaporation-induced crystallization (RTSEIC) method is reported based on Le Chatelier's principle, which provides a general strategy to grow halide perovskite single crystals including 3D, 2D, 1D, and 0D, and either hybrid or all-inorganic halide perovskites. Taking 2D n-BA2 PbBr4 (n-BA = butylammonium) as an example, the room-temperature crystallization kinetics is demonstrated. The centimeter-sized n-BA2 PbBr4 single crystals exhibit an extremely small full width at half maximum (FWHM) of 0.024° in (0 0 2) plane rocking curve and a small trap density of 2.74 × 1010 cm-3 . The superior crystalline quality endows the n-BA2 PbBr4 single crystal ultraviolet photodetectors with recorded performance among reported n-BA2 PbBr4 ultraviolet photodetectors, demonstrating a detectivity reaching 1.8 × 1013 Jones, a fast response time of 55 µs and a high on-off ratio of 104 . The low-cost, simple, general, and efficient RTSEIC method is anticipated to promote the blossoming of halide perovskites single crystals.

Sublimation of Drugs from the Site of Application of Topical Products.

The objective of the project was to investigate the plausibility of active pharmaceutical ingredients (APIs) to undergo sublimation from topical application following evaporation of solvent. Topical formulations with different APIs were subjected to a sublimation screening test. The APIs in the selected topical products were found to undergo sublimation to a different extent. The salicylic acid topical product was found to undergo a significant loss due to sublimation. The extent of sublimation of salicylic acid was significantly greater at skin temperature compared to room temperature. When the APIs were subjected to the sublimation screening test in their neat form at 32 ± 1 °C, the natural log of the rate of sublimation decreased linearly with the standard enthalpy of sublimation of compound (R2 = 0.89). The formulation composition was found to have a significant impact on the extent of sublimation of the representative API, salicylic acid. The sublimation of APIs from the topical product was found to affect the mass balance studies in the case of the salicylic acid ointment. Furthermore, the results of the human studies agreed with the in vitro experimental results demonstrating the plausibility of loss of API due to sublimation from the site of application.

Methods for preparation of nanostructured lipid carriers.

Construction of nanocarriers of different structures and properties have shown great promise as delivery systems for a wide range of drugs to improve therapeutic effects and reduce side effects. Nanostructured lipid carriers (NLCs) have been introduced as a new generation of solid lipid nanoparticles (SLNs) to overcome several of the limitations associated with the SLNs. NLCs consist of a blend of solid and liquid lipids which result in a partially crystallized lipid system that enables higher drug loading efficiency compared to SLNs. Owing to their biocompatibility, low toxicity, ease of preparation and scaling-up, and high stability, NLCs have been exploited in numerous pharmaceutical applications. Different methods for fabrication of NLCs have been described in the literature. In this article, procedures involved in emulsification-solvent evaporation method, one of the commonly utilized methods for preparation of NLCs, are described in detail. Critical aspects that should be considered throughout preparation process are also highlighted to allow for consistent and reproducible construction of NLCs.

Electrochemical detection of arsenic (III) hazardous chemicals using cubic CsPbBr3 single crystals: Structural insights from DFT study.

Long-term exposure to the highly toxic heavy metal arsenic can harm ecological systems and pose serious health risks to humans. Arsenic pollutant in water and the food chain must be addressed, and active prompt detection of As(III) is essential. The development of an effective detection method for As(III) ions is urgently needed to slow the alarming growth of arsenic pollution in the environment and safeguard the well-being of future generations. This study presents the results of our exhaustive investigation into cubic CsPbBr3 single crystals, the glassy carbon (GC) electrode modification with CsPbBr3 single crystals prepared by direct solvent evaporation, as well as our observations of the material's remarkable electrocatalytic properties and exceptional anti-interference sensing of As(III) ions in neutral pH media. The developed CsPbBr3/GC is exceptionally useful for the ultra-sensitive and specific identification of arsenic in water, exhibiting a detection limit of 0.381 µmol/L, a rapid response across a defined range of 0.1-25 µmol/L, and an ultra-sensitivity of 0.296 µA/µmolL-1. CsPbBr3/GCE (prepared without a specific reagent) is superior to other modified electrodes used as sensors in electrocatalytic activity, detection limit, analytical sensitivity, and stability response.

Development of a porous layer-by-layer microsphere with branched aliphatic hydrocarbon porogens.

Porous polymer microspheres are employed in biotherapeutics, tissue engineering, and regenerative medicine. Porosity dictates cargo carriage and release that are aligned with the polymer physicochemical properties. These include material tuning, biodegradation, and cargo encapsulation. How uniformity of pore size affects therapeutic delivery remains an area of active investigation. Herein, we characterize six branched aliphatic hydrocarbon-based porogen(s) produced to create pores in single and multilayered microspheres. The porogens are composed of biocompatible polycaprolactone, poly(lactic-co-glycolic acid), and polylactic acid polymers within porous multilayered microspheres. These serve as controlled effective drug and vaccine delivery platforms.

Evaluation of six different one-step universal adhesive systems in terms of dentin bond strength, adhesive interface characterization, surface tension, contact angle, degree of conversion and solvent evaporation after immediate and delayed use.

OBJECTIVES: In this study, it was aimed to investigate the effects of different waiting periods on resin-dentin bond strength (BS), degree of conversion (DC), contact angle (CA), surface tension (ST), solvent evaporation (weight loss) and the characteristics of adhesive interfaces of the current six universal adhesive resins (ARs). MATERIALS AND METHODS: A total of 216 caries-free human lower third molar teeth were used. Composite resin restorations were performed by applying six universal ARs in etch-and-rinse and self-etch mode on standardized dentin surfaces after 0, 5, and 30 min waiting time. Then, a micro-shear BS test, SEM examination and characterization of the adhesive interface were performed. In addition, DC, CA, ST, solvent evaporation of all tested ARs were evaluated. RESULTS: The obtained data were statistically anaIyzed. The tested ARs did not show any statistical difference between 0 and 5 min evaluations in all parameters evaluated except for weight loss (p > 0.05). While the weight loss, ST and CA of all ARs increased in 30 min (p < 0.05), the BS, DC, thickness of the adhesive layer and the hybrid layer, resin tag length and number of resin tags varied according to the ARs used. When the ARs were used in etch-and-rinse mode, all the parameters evaluated also varied according to the AR used. Higher adhesive layer thickness and lower hybrid layer thickness were found in the self-etch mode (p < 0.05). CONCLUSIONS: All of the adhesives tested can be safely used up to 30 min. This could also prevent economical loss caused by waste adhesive material. CLINICAL SIGNIFICANCE: It is important to know how the bond strength, degree of conversion, adhesion, contact angle and surface tension properties of the adhesive resin waiting in the dispensing cup for a long time during clinical use are affected to make ideal restorations.

Does extended air-drying time improve bond strength of universal adhesives to enamel?

OBJECTIVE: To investigate the effect of extended air-drying time on the microshear bond strength (MSBS) of universal adhesives to enamel. MATERIALS AND METHODS: The distal and mesial specimens from third molars were wet-ground and randomly assigned to three groups according to adhesives tested (n = 60): Clearfil Bond Universal, Gluma Bond Universal, and G-Premio Bond. The adhesives were applied in etch-and-rinse or self-etch modes, followed by air-drying for 5, 15, or 25 s. Composite buildups were constructed and subjected to the MSBS test after 24-h or thermocycling. MSBS results were evaluated using a four-way ANOVA. The thickness of the adhesive layer and the degree of solvent evaporation were further evaluated. RESULTS: At 24-h, MSBS of G-Premio Bond significantly improved with the 25 s air-drying in both of the etching modes when compared to the 5 s air-drying. After thermocycling, the extended air-drying did not produce a significant difference on the MSBS, regardless of the application strategy. Extended air-drying (25 s) evaporated almost all of the volatile part of Gluma Bond Universal and G-Premio Bond. CONCLUSIONS: Extended air-drying times increased solvent evaporation but did not contribute to the bonding effectiveness of the adhesives, regardless of the etching mode. CLINICAL SIGNIFICANCE: Air-drying applications for more than 5 s had no significant effect on enamel bonding performance of universal adhesives.

Phospholipid Complexation for Bioavailability Improvement of Albendazole: Preparation, Characterization and In Vivo Evaluation.

The current study aimed to improve the poor solubility of albendazole (ABZ) by means of phospholipid complexation, hence to improve its oral bioavailability. The solvent-evaporation method for ABZ-phospholipid complex (ABZ-PC) preparation was established for the first time. And a systematic optimization of preparation conditions of ABZ-PC was performed. Physicochemical studies of ABZ-PC were performed with FTIR, DSC, and XRD measurements to confirm the formation of the ABZ-PC and reveal the interaction mechanism between ABZ and phospholipid molecules. Solubility determination and morphological characterization were applied to verify the solubility improvement of prepared ABZ-PC. Moreover, the pharmacokinetic performance of ABZ-PC was further evaluated in vivo compared with raw materials of ABZ. Under optimal preparation conditions, the AE of ABZ-PC could be approximately 100%. Physicochemical studies indicated that the P = O group in the phospholipid molecule would interact with the N-H group in the ABZ molecule through hydrogen bonds and ABZ was dispersed in an amorphous state after being prepared into ABZ-PC. The aqueous solubility of ABZ-PC in deionized water (pH7.0) improved by 30-folds than free ABZ, and the AUC0-t of ABZ-PC was significantly increased by 2.32 times in comparison with raw materials of ABZ through oral administration. The current study developed an effective method for the phospholipid complexation of ABZ. With significantly improved solubility in an aqueous environment, the prepared ABZ-PC exhibited improved oral bioavailability and pharmacokinetic characteristics indicating it could be potentially applied in the oral drug delivery of ABZ.

Construction of Multiform Hollow-Structured Covalent Organic Frameworks via a Facile and Universal Strategy for Enhanced Sonodynamic Cancer Therapy.

The special structural morphology of hollow covalent organic frameworks (HCOFs) has an important influence on their applications. However, the rapid and precise control of morphology for HCOFs still remains largely challenging. Herein, we present a facile and universal two-step strategy based on solvent evaporation and oxidation of imine bond for the controllable synthesis of HCOFs. The strategy enables to prepare HCOFs in a greatly shortened reaction time and seven kinds of HCOFs are fabricated by the oxidation of imine bond via hydroxyl radicals (⋅OH) generated from Fenton reaction. Importantly, a fascinating library of HCOFs with diverse nanostructures, including bowl-like, yolk-shell, capsule-like and flower-like morphologies, has been ingeniously constructed. Owing to the large cavities, the obtained HCOFs are ideal candidates for drug delivery, which are employed to load five small molecule drugs, achieving the enhanced sonodynamic cancer therapy in vivo.

Insight into Fucoidan-Based PEGylated PLGA Nanoparticles Encapsulating Methyl Anthranilic Acid: In Vitro Evaluation and In Vivo Anti-Inflammatory Study.

A potential fucoidan-based PEGylated PLGA nanoparticles (NPs) offering a proper delivery of N-methyl anthranilic acid (MA, a model of hydrophobic anti-inflammatory drug) have been developed via the formation of fucoidan aqueous coating surrounding PEGylated PLGA NPs. The optimum formulation (FuP2) composed of fucoidan:m-PEG-PLGA (1:0.5 w/w) with particle size (365 ± 20.76 nm), zeta potential (-22.30 ± 2.56 mV), % entrapment efficiency (85.45 ± 7.41), drug loading (51.36 ± 4.75 µg/mg of NPs), % initial burst (47.91 ± 5.89), and % cumulative release (102.79 ± 6.89) has been further investigated for the anti-inflammatory in vivo study. This effect of FuP2 was assessed in rats' carrageenan-induced acute inflammation model. The average weight of the paw edema was significantly lowered (p ≤ 0.05) by treatment with FuP2. Moreover, cyclooxygenase-2 and tumor necrosis factor-alpha immunostaining were decreased in FuP2 treated group compared to the other groups. The levels of prostaglandin E2, nitric oxide, and malondialdehyde were significantly reduced (p ≤ 0.05) in the FuP2-treated group. A significant reduction (p ≤ 0.05) in the expression of interleukins (IL-1ß and IL-6) with an improvement of the histological findings of the paw tissues was observed in the FuP2-treated group. Thus, fucoidan-based PEGylated PLGA-MA NPs are a promising anti-inflammatory delivery system that can be applied for other similar drugs potentiating their pharmacological and pharmacokinetic properties.

Polymer type effect on PLGA-based microparticles preparation by solvent evaporation method with single emulsion system using focussed beam reflectance measurement.

AIM: This study aimed to investigate the effect of polymer type on solidification rate of PLGA polymeric microparticles and particle size/distribution of the emulsion droplets/hardened PLGA polymeric microparticles during solvent evaporation process using FBRM (Focussed Beam Reflectance Measurement). METHODS: PLGA polymeric microparticles were prepared by an O/W solvent evaporation method using various PLGA polymers, including PLGA Resomer® RG503H, RG502H and RG752H. The particle size mean, chord length distribution (CLD), and chord count of the emulsion droplets/hardened microparticles were monitored by FBRM. The morphology of polymeric microparticles were characterised by optical microscopy and scanning electron microscopy (SEM). RESULTS: The transformation of the emulsion droplets into solid microparticles occurred within the first 30 (± 1.04), 34 (± 1.15) and 37 (± 0.82) min and square weighted mean chord lengths are 64.08 (± 3.18), 52.36 (± 5.27) and 42.18 (± 4.61) µm when PLGA Resomer® RG503H, RG502H and RG752H were used respectively. Larger square weighted mean chord length of PLGA polymeric microparticles gave lower chord counts. PLGA RG752H microparticles gave smallest square weighted mean chord length and the chord counts was the highest. The CLDs measured by FBRM showed that a larger particle size mean gave longer CLD and a lower peak of particle number. SEM data revealed that the morphology of microparticles was influenced by type and physical properties of polymer. CONCLUSIONS: FBRM can be employed for online monitoring of the shift in the microparticle CLD and detect transformation of the emulsion droplets into solid microparticles during the solvent evaporation process. The microparticle CLD and transformation process were strongly influenced by polymer type.

Pioglitazone-Loaded PLGA Nanoparticles: Towards the Most Reliable Synthesis Method.

Recent findings have proved the benefits of Pioglitazone (PGZ) against atherosclerosis and type 2 diabetes. Since the systematic and controllable release of this drug is of significant importance, encapsulation of this drug in nanoparticles (NPs) can minimize uncontrolled issues. In this context, drug delivery approaches based on several poly(lactic-co-glycolic acid) (PLGA) nanoparticles have been rising in popularity due to their promising capabilities. However, a fully reliable and reproducible synthetic methodology is still lacking. In this work, we present a rational optimization of the most critical formulation parameters for the production of PGZ-loaded PLGA NPs by the single emulsification-solvent evaporation or nanoprecipitation methods. We examined the influence of several variables (e.g., component concentrations, phases ratio, injection flux rate) on the synthesis of the PGZ-NPs. In addition, a comparison of these synthetic methodologies in terms of nanoparticle size, polydispersity index (PDI), zeta potential (ζp), drug loading (DL%), entrapment efficiency (EE%), and stability is offered. According to the higher entrapment efficiency content, enhanced storage time and suitable particle size, the nanoprecipitation approach appears to be the simplest, most rapid and most reliable synthetic pathway for these drug nanocarriers, and we demonstrated a very slow drug release in PBS for the best formulation obtained by this synthesis.

A Comparative Loading and Release Study of Vancomycin from a Green Mesoporous Silica.

Since its first use as a drug delivery system, mesoporous silica has proven to be a surprisingly efficient vehicle due to its porous structure. Unfortunately, most synthesis methods are based on using large amounts of surfactants, which are then removed by solvent extraction or heat treatment, leading to an undesired environmental impact because of the generated by-products. Hence, in the present study, we followed the synthesis of a silica material with a wormhole-like pore arrangement, using two FDA-approved substances as templates, namely Tween-20 and starch. As far as we know, it is the first study using the Tween-20/starch combo as a template for mesoporous silica synthesis. Furthermore, we investigated whether the obtained material using this novel synthesis had any potential in using it as a DDS. The material was further analyzed by XRD, TEM, FT-IR, N2 adsorption/desorption, and DLS to investigate its physicochemical features. Vancomycin was selected as the active molecule based on the extensive research engaged towards improving its bioavailability for oral delivery. The drug was loaded onto the material by using three different approaches, assuming its full retention in the final system. Thermal analysis confirmed the successful loading of vancomycin by all means, and pore volume significantly decreased upon loading, especially in the case of the vacuum-assisted method. All methods showed a slower release rate compared to the same amount of the pure drug. Loadings by physical mixing and solvent evaporation released the whole amount of the drug in 140 min, and the material loaded by the vacuum-assisted method released only 68.2% over the same period of time, leading us to conclude that vancomycin was adsorbed deeper inside the pores. The kinetic release of the three systems followed the Higuchi model for the samples loaded by physical mixing and vacuum-assisted procedures, while the solvent evaporation loading method was in compliance with the first-order model.

Preparation, characterisation and comparative toxicity of nanopermethrin against Anopheles stephensi and Culex pipiens.

OBJECTIVES: To assess the effectiveness of nanopermethrin as a potential new formulation for pest and vector control. METHODS: Permethrin nanoparticles were prepared by the ionic gelation method and its structure and the formulations were designed using Box-Behnken statistical technique. The effect of independent variables (Chitosan/Permethrin ratio, tripolyphosphate quantity, sonication time) on the properties of nanoparticles was investigated to determine the optimal formulation. RESULTS: The size of the nanoparticles ranged from 135.27 ± 5.88 to 539.5 ± 24.01 nm and the insecticide entrapment efficiency per cent (EE%) ranged from 7.72 ± 1.36 to 63.59 ± 3.17%. Anopheles stephensi larvae were then bioassayed with the nanopermethrin and compared with the results of the bioassay with the mother molecule of permethrin using a standard WHO-recommended mosquito larval bioassay kit. LC50 with permethrin and nanopermethrin on larvae of An. stephensi were 0.125 and 0.026 ppm showing a 4.8 times difference. The LC50 for permethrin and nanopermethrin on Culex pipiens were 0.003 and 0.00032 ppm, respectively, showing a 9.4-fold difference. CONCLUSION: Nanopermethrin is much more potent than its mother molecule against larvae of An. stephensi and Cx. pipiens.