Drug Release of pH/Temperature‐Responsive Calcium Alginate/Poly(N‐isopropylacrylamide) Semi‐IPN Beads

Abstract

A series of semi-interpenetrating, polymer network (semi-IPN), hydrogel beads, composed of calcium alginate (Ca-alginate) and poly(N-isopropylacrylamide) (PNIPAAM), were prepared for a pH/temperature-sensitive drug delivery study. The equilibrium swelling showed the independent pH- and thermo- responsive nature of the developed materials. At pH=2.1, the release amount of indomethacin incorporated into these beads was about 10% within 400 min, while this value approached to 95% at pH=7.4. The release rate of the drug was higher at 37 degrees C than that at 25 degrees C and increased slightly with increasing PNIPAAM content. These results suggest that the Ca-alginate/PNIPAAM beads have the potential to be used as an effective pH/temperature sustainable delivery system of bioactive agents. [GRAPHS: SEE TEXT] A summary of the temperature- and pH-dependence on the release of the drug over a period of 450 min. The effect of the temperature on the swelling of the beads is shown in the inset.

Stimuli‐Responsive Polymeric Systems for Biomedical Applications

“…An example included the combination of alginate and PNIPAAm where the pH-responsive polysaccharide was crosslinked with calcium ions. [75] The swelling of the obtained beads were highly dependent on both temperature and pH, and strong deviations were also found in the delivery profile of indomethacin -see Figure 3(a). In order to try to slow down the release profile, such particles were coated with chitosan, followed by alginate.…”

Protein‐responsive imprinted polymers with specific shrinking and rebinding

“…(Byrne et al, 2002;Gil and Hudson, 2004). Due to their large volume changes, smart hydrogels have been widely used in many interesting applications including controlled drug delivery (Shi et al, 2006), enzyme and cell immobilization (Yasui et al, 1997), and immunoassays (Lin et al, 2005). Recently, bio-responsive hydrogels that can undergo swelling/shrinking when exposed to bio-molecules have received great attention since these smart materials are of special interest in developing devices for molecular diagnostics and biological sensing (Miyata et al, 2002;Alarcó n et al, 2005).…”

Synthesis of Temperature-Responsive Dextran-MA/PNIPAAm Particles for Controlled Drug Delivery Using Superhydrophobic Surfaces

“…The purpose of combining PNIPAAm and dextran was to obtain temperature-responsive beads (20,21,(34)(35)(36). The temperature sensitiveness of the beads was analyzed through the water uptake quantification once immersed in PBS solution for 24 h cycles at 4°C and 37°C.…”

“…As discussed elsewhere, hydrophilic polysaccharides incorporated into PNIPAAm hydrogels may help to fasten the response to temperature, as compared with the pure PNIPAAm, and may prevent the so-called skin effect (20). Several interpenetrated (IPN) and semi-interpenetrated (semi-IPN) networks of PNIPAAm have been proposed as stimuliresponsive materials for drug delivery applications (21)(22)(23). The semi-IPN Dextran-PNIPAAm hydrogel developed in this work was chosen to demonstrate the possibility of producing smart beads for drug delivery applications using superhydrophobic surfaces.…”