Microencapsulation and Nanoencapsulation Using Supercritical Fluid (SCF) Techniques.

The unique properties of supercritical fluids, in particular supercritical carbon dioxide (CO₂), provide numerous opportunities for the development of processes for pharmaceutical applications. One of the potential applications for pharmaceuticals includes microencapsulation and nanoencapsulation for drug delivery purposes. Supercritical CO₂ processes allow the design and control of particle size, as well as drug loading by utilizing the tunable properties of supercritical CO at different operating conditions (flow ratio, temperature, pressures, etc.

Drug delivery systems for programmed and on-demand release.

With the advancement in medical science and understanding the importance of biodistribution and pharmacokinetics of therapeutic agents, modern drug delivery research strives to utilize novel materials and fabrication technologies for the preparation of robust drug delivery systems to combat acute and chronic diseases. Compared to traditional drug carriers, which could only control the release of the agents in a monotonic manner, the new drug carriers are able to provide a precise control over the release time and the quantity of drug introduced into the patient's body. To achieve this goal, scientists have introduced "programmed" and "on-demand" approaches.

Diphenylalanine peptide nanotubes self-assembled on functionalized metal surfaces for potential application in drug-eluting stent.

This study focuses on the potential of diphenylalanine self-assembled peptide nanotubes (FF Nts) for delivery of flufenamic acid (FA) from metal implants. Self-assembly of FF Nts was studied in solution and on surfaces of glass, silicone and gold substrates. FA was loaded inside the shell of FF Nts and subsequently FF/FA Nts were attached to gold surfaces.

Lysine-based peptide-functionalized PLGA foams for controlled DNA delivery.

Due to its hydrophobicity and negatively charged surfaces, PLGA-based scaffolds have encountered problems in controlled-release and tissue engineering applications. The effects of charge modification of PLGA micro-porous foams on DNA delivery and DNA transfection are investigated herein. Tailor-designed l-lysine peptides (K4 and K20) were employed to modify the surface charge of PLGA foams using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide cross linkers and the effects of charge modification of PLGA were examined in three main aspects: DNA adsorption, DNA release properties and DNA transfection.

Paclitaxel delivery from PLGA foams for controlled release in post-surgical chemotherapy against glioblastoma multiforme.

Paclitaxel loaded biodegradable poly-(DL-lactic-co-glycolic) acid (PLGA) foams with microporous matrix were fabricated by a novel pressure quenching approach to provide a sustained paclitaxel release. The foams with micropores provided increased surface area to volume ratio and were also implantable for post-surgical chemotherapy applications. The two formulations 5% (w/w) paclitaxel loaded PLGA 85:15 foam (F1) and 10% (w/w) paclitaxel loaded PLGA 50:50 foam (F2), were evaluated in vitro and in vivo.

Characterization of porous poly(D,L-lactic-co-glycolic acid) sponges fabricated by supercritical CO2 gas-foaming method as a scaffold for three-dimensional growth of Hep3B cells.

This study presents the application of the porous poly(D,L-lactic-co-glycolic acid) (PLGA) sponges fabricated from an organic solvent free supercritical gas foaming technique. Two formulations of PLGA sponges with different co-polymer compositions (85:15 and 50:50) were fabricated as novel scaffolds to guide human hepatoma cell line, Hep3B cell growth in vitro. The PLGA sponges showed desirable biodegradability and exhibited uniform pore size distribution with moderate interconnectivity.

PLGA/chitosan composites from a combination of spray drying and supercritical fluid foaming techniques: new carriers for DNA delivery.

The use of poly(D, L-lactic-co-glycolic acid) for DNA delivery application is limited by its negative surface charge and acidic degradation products. The motivation of the present work was to study the effects of chitosan incorporation into PLGA foams on DNA delivery. PLGA/chitosan composite foams loaded with luciferase plasmid were fabricated by a combination of spray drying and supercritical CO2 foaming techniques.

Supercritical antisolvent production of biodegradable micro- and nanoparticles for controlled delivery of paclitaxel.

Paclitaxel and poly (L-Lactic acid) (PLA) were co-precipitated to form micro and submicron particles in a manner similar to that used in the supercritical antisolvent with enhanced mass transfer (SAS-EM) process. As compared with conventional processes, a major advantage of supercritical CO(2) as an antisolvent in the SAS-EM process is the effective removal of residual organic solvents. In this work, the organic phase was sprayed into supercritical CO(2) (for CO(2), Tc=31.

Encapsulation of protein drugs in biodegradable microparticles by co-axial electrospray.

A co-axial electrospray process was developed to encapsulate protein-based drugs in biodegradable polymeric microparticles eliminating the key problem faced by other conventional methods of protein encapsulation--the primary emulsion being a major cause for protein denaturation and aggregation. Bovine serum albumin (BSA) and lysozyme were chosen as model protein drugs for this study. Scanning electron microscopy observation of the morphology of particles showed spherical microparticles of several microns could be achieved.

Mathematical modeling and simulation of drug release from microspheres: Implications to drug delivery systems.

This article aims to provide a comprehensive review of existing mathematical models and simulations of drug release from polymeric microspheres and of drug transport in adjacent tissues. In drug delivery systems, mathematical modeling plays an important role in elucidating the important drug release mechanisms, thus facilitating the development of new pharmaceutical products by a systematic, rather than trial-and-error, approach. The mathematical models correspond to the known release mechanisms, which are classified as diffusion-, swelling-, and erosion-controlled systems.