Nanomaterials and supercritical fluids

Formation, characterization, and fate of inhaled drug nanoparticles

Nanoparticles bring many benefits to pulmonary drug delivery applications, especially for systemic delivery and drugs with poor solubility. They have recently been explored in pressurized metered dose inhaler, nebulizer, and dry powder inhaler applications, mostly in polymeric forms. This article presents a review of processes that have been used to generate pure (non polymeric) drug nanoparticles, methods for characterizing the particles/formulations, their in-vitro and in-vivo performances, and the fate of inhaled nanoparticles.

Production of Ursolic Acid Nanoparticles by Supercritical Antisolvent Precipitation

The aim of this study was to obtain nanoparticles and improve solubility of ursolic acid (UA), using supercritical antisolvent process (SAS). The four effects of process variables on drug particle formation during SAS process were investigated. Particles with mean particle size ranging from 139.4 ± 19.4 to 1039.8 ± 65.2 nm were obtained. The UA was characterized by scanning electron microscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy, specific surface area and dissolution test. The XRD analyses showed that the processed UA was amorphous. The processed UA had solubility 4.4 times higher than the unprocessed UA.

Insulin nanoparticles for transdermal delivery: preparation and physicochemical characterization and in vitro evaluation

AIM

This work is aimed to study the feasibility of insulin nanoparticles for transdermal drug delivery (TDD) using supercritical antisolvent (SAS) micronization process.

METHODS

The influences of various experimental factors on the mean particle size (MPS) of insulin nanoparticles were investigated. Moreover, the insulin nanoparticles obtained were characterized by scanning electron microscopy (SEM), dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetric (TG) analyses.

RESULTS

Under optimum conditions, uniform spherical insulin nanoparticles with a MPS of 68.2 +/- 10.8 nm were obtained. The Physicochemical characterization results showed that SAS process has not induced degradation of insulin. Evaluation in vitro showed that insulin nanoparticles were accorded with the Fick's first diffusion law and had a high permeation rate.

CONCLUSION

These results suggest that insulin nanoparticles can have a great potential in TDD systems of diabetes chemotherapy.

Design of submicron and nanoparticle delivery systems using supercritical carbon dioxide-mediated processes: an overview

Supercritical carbon dioxide technology is an environmentally benign technique that allows precise control of particle morphology, while minimizing organic solvent use for a wide variety of biomedical and pharmaceutical applications. Supercritical carbon dioxide processes have benefits over the conventional particle formation methods in terms of improved control, flexibility and operational ease. This article gives an insight into a variety of supercritical fluid techniques relevant to drug formulation, recent advances and novel applications in the field of controlled delivery. These new methods have been designed to alleviate the scaling-up of the traditional methods for nanoparticle formulation either in the form of polymeric scaffolds, impregnation or nanoencapsules using a simple one-step process to produce micron-size particles.

Experimental setup forin situX-ray SAXS/WAXS/PDF studies of the formation and growth of nanoparticles in near- and supercritical fluids

The growing interest in inorganic nanoparticles for a wide range of applications is spurring a need for synthesis methods that allow a highly specific tailoring of material properties. Synthesis in supercritical fluids holds great promise for solving this problem, but so far the fundamental chemical processes taking place under these conditions are to a large extent unknown. Here the design, construction and application of a versatile experimental setup are reported; this setup enablesin situsynchrotron small-angle X-ray scattering/wide-angle X-ray scattering/pair distribution function (SAXS/WAXS/PDF) studies of the formation and growth of nanoparticles under supercritical fluid conditions.

Formation of silver iodide nanoparticles on silk fiber by means of ultrasonic irradiation

The growth of silver iodide nanoparticles on silk fiber was achieved by sequential dipping in an alternating bath of potassium iodide and silver nitrate under ultrasound irradiation. Some parameters such as effect of pH, concentration and numerous sequential dipping in growth of the nanocrystal have been studied. The samples were characterized with powder X-ray diffraction (XRD), scanning electron microscopy (SEM), ICP, TGA and solid state UV-vis spectroscopy.

Syntheses and characterization of AgI nano-structures by ultrasonic method: Different morphologies under different conditions

Nano-structures of AgI have been prepared by reaction between AgNO(3) and KI under ultrasound irradiation. Some of parameters such as effect of stirring, temperature, sonicating time in growth and morphology of the nano-structures have been studied. The sizes distributions depend slighter on reaction conditions. But, morphology of nano-structure depends strongly on reaction parameters. With change of solvent concentration and sonicating time, nanoparticles structures changed to nanowires. An increasing of temperature results in an increasing of solubility. As a result, nuclei with small sizes become unstable and dissolve back into the solution. Attendance or non-attendance of stirring is another parameter that effects on morphology of nano-structures. In some conditions, non-attendance of stirring led to nanowires structure and in the other conditions, nanoparticles structures were prepared. The samples were characterized with powder X-ray diffraction (XRD), scanning electron microscopy (SEM).