Thermo-sensitive microparticles of PNIPAM-grafted ethylcellulose by spray-drying method

Abstract

The thermo-sensitive polymer, PNIPAM-grafted ethylcellulose, was synthesized and it was confirmed by FTIR spectroscopy that PNIPAM was successfully grafted onto ethylcellulose. Microparticles were prepared by the spray-drying method using a B-191 Mini Spray Dryer. Their morphology, observed by scanning electron microscopy (SEM), showed irregular spheres with rugged surfaces, and narrow size distribution. In a model delivery system, ethylcelullose-g-PNIPAM was used as the polymer wall material and allopurinol was used as the model drug. The release rate of allopurinol from ECGPN8 microparticles was slower at 40 degrees C (above the LCST) than that of 25 degrees C (below the LCST), probably due to the collapse of PNIPAM chains by temperature. Although PNIPAM was the large part of wall material, the thermo-sensitive release behavior was not so obvious. It is believed that the release of allopurinol from the microparticles is more dependent on the porous structure of microparticles than the conformational change of PNIPAM, created by the rapid evaporation of solvent during the spray-drying process.

“Smart” Materials Based on Cellulose: A Review of the Preparations, Properties, and Applications

“…Then the modified HEC with pendant alkene groups was crosslinked with NIPAm initiated by KPS in DMF/water system to obtain the temperature-sensitive hydrogels. EC was grafted with NIPAm in chloroform/DMSO solvent system initiated by APS, then the EC- g -PNIPAm was dissolved in CH 2 Cl 2 with allopurinol as a model drug to produce thermo-responsive drug delivery microparticles using a B-191 mini spray-dryer [61]. Yuan et al prepared a type of tunable pH- and temperature-responsive EC brush polymers with mono and dual side chains by click chemistry [62].…”

Stimuli‐Responsive Hydrogels Based on Polysaccharides Incorporated with Thermo‐Responsive Polymers as Novel Biomaterials

“…[124] In order to increase its controlled release ability, PNIPAAm was grafted onto ethylcellulose. [125] The release rate of allopurinol (the model drug) from the PNIPAAmg-ethylcellulose microparticles was found to be slower at 40 than at 25 8C, probably due to the collapse of the PNIPAM chains due to the temperature. Although PNIPAAm was the large part of wall material, the thermosensitive release behavior was not found to be so obvious.…”

PNIPAM: a thermo-activated nano-material for use in optical devices

“…PNIPAM polymers are well hydrated and swollen in their hydrophilic state (below 32°C), while they release water and collapse in the hydrophobic one (above 32°C). This remarkable property of PNIPAM chains can find the use in various domains including protein screening and fractionation (Huber et al 2003), controlled drug and gene delivery (Kim et al 2002;Twaites et al 2004), micro-actuators (Lopez et al 2002), micro-valves (Lopez et al 2002) and optical devices (Reese et al 2004;Asher et al 2000;Akashi et al 2002;Dong et al 2006).…”