In this work, smart hollow microcapsules made of thermal-/pH-dual sensitive aliphatic poly(urethane-amine) (PUA), sodium poly(styrenesulfonate) (PSS), and Au nanoparticles (AuNPs) for interdependent multi-responsive drug delivery have been constructed by layer-by-layer (LbL) technique. The electrostatic interactions among PUA, PSS, and AuNPs contribute to the successful self-assembly of hollow multilayer microcapsules. Thanks to the shrinkage of PUA above its lower critical solution temperature (LCST) and the interaction variation between PUA and PSS at different pH conditions, hollow microcapsules exhibit distinct pH- and thermal-sensitive properties. Moreover, AuNPs aggregates can effectively convert light to heat upon irradiation with near-infrared (NIR) laser and endow the hollow microcapsules with distinct NIR-responsiveness. More importantly, the NIR-responsive study also demonstrates that the microcapsule morphology and the corresponding NIR-responsive drug release are strongly dependent on the pH value and temperature of the media. The results indicate that the prepared hollow PUA/PSS/Au microcapsules have the great potential to be used as a novel smart drug carrier for the remotely controllable drug delivery. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43008.

Poly(N-isopropylacrylamide) (PNIPAAm)/calcium carbonate (CaCO₃) micro/nanohybrid composites with smart drug-delivery property had been prepared via in situ biomineralization reaction. Sodium poly(styrene sulfonate) (PSS) was used as the crystal growth additive to control the crystalline polymorph of CaCO₃ and the morphology of the hybrid materials. The interaction between PSS and Ca²⁺ contributed to the formation of hierarchical micro/nanohybrid composites, in which microscale vaterite microparticles were covered by nanoscale PNIPAAm micelle. Vitamin B₂ (VB₂) release behavior was found to be pH- and thermal-responsive. Moreover, the release profiles were sustained with the introduction of CaCO₃ microparticles, suggesting that CaCO₃ microparticles could hinder the permeation of the encapsulated VB₂ and reduce the drug release effectively. The prepared micro/nanohybrid materials can be used as “smart” hierarchical materials for controlled drug delivery. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Polysaccharide-based thermo-responsive material was prepared by grafting PNIPAAm onto hybrid alginate beads, in which a biomineralized polyelectrolyte layer was constructed aiming to enhance the mechanical strength and ensure higher graft efficiency. XPS results demonstrated that the incorporation of PNIPAAm to the hybrid beads was successful, and the PNIPAAm-grafted beads were more hydrophilic than the ungrafted ones as indicated by their swelling behavior. The drug release behaviors revealed that the grafted beads were both thermo- and pH-sensitive, and the PNIPAAm existed in the pores of the alginate beads acted as the “on–off” gates: the pores of the beads were covered by the stretched PNIPAAm to delay the drug release at 25°C and opened to accelerate the drug release at 37°C because of the shrinking of PNIPAAm molecules. This paper would be a useful example of grafting thermo-responsive polymers onto biodegradable natural polymer substrate. The obtained beads provide a new mode of behavior for thermo-responsive “smart” polysaccharide materials, which is highly attractive for targeting drug delivery system and chemical separation. Copyright © 2010 John Wiley & Sons, Ltd.

To improve the mechanical strength of natural hydrogels and to obtain a sustained drug-delivery device, temperature-/pH-sensitive hydrogel beads composed of calcium alginate (Ca-alginate) and poly(N-isopropylacrylamide) (PNIPAAm) were prepared in the presence of poly(sodium acrylate) (PAANa) with ultrahigh molecular weight (M_η ≥ 1.0 × 10⁷) as a strengthening agent. The influence of PAANa content on the properties, including the beads stability, swelling, and drug-release behaviors, of the hydrogels was evaluated. Scanning electron microscopy and oscillation experiments were used to analyze the structure and mechanical stability of the hydrogel beads, respectively. The results show that stability of the obtained Ca-alginate/PNIPAAm hydrogel beads strengthened by PAANa the alginate/poly(N-isopropyl acrylamide) hydrogel bead (SANBs) was significantly improved compared to that of the beads without PAANa (NANBs) at pH 7.4. The swelling behavior and drug-release capability of the SANBs were markedly dependent on the PAANa content and on the environmental temperature and pH. The bead sample with a higher percentage of PAANa exhibited a lower swelling rate and slower drug release. The drug release profiles from SANBs were further studied in simulated intestinal fluid, and the results demonstrated here suggest that SANBs could serve as a potential candidate for controlled drug delivery in vivo. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011