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This work developed novel chitosan-halloysite nanotubes (HNTs) nanocomposite (NC) scaffolds by combining solution-mixing and freeze-drying techniques, and aimed to show the potential application of the scaffolds in tissue-engineering. The hydrogen bonding and electrostatic attraction between chitosan and HNTs were confirmed by spectroscopy and morphology analysis. The interfacial interactions resulted in a layer of chitosan absorbed on the surfaces of HNTs. The determination of mechanical and thermal properties demonstrated that the NC scaffolds exhibited significant enhancement in compressive strength, compressive modulus, and thermal stability compared with the pure chitosan scaffold. But the NC scaffolds showed reduced water uptake and increased density by the incorporation of HNTs. All the scaffolds exhibited a highly porous structure and HNTs had nearly no effect on the pore structure and porosity of the scaffolds. In order to assess cell attachment and viability on the materials, NIH3T3-E1 mouse fibroblasts were cultured on the materials. Results showed that chitosan-HNTs nanocomposites were cytocompatible even when the loading of HNTs was 80%. All these results suggested that chitosan-HNTs NC scaffolds exhibited great potential for applications in tissue engineering or as drug/gene carriers.

Surfaces play an important role in a biological system for most biological reactions occurring at surfaces and interfaces. The development of biomaterials for tissue engineering is to create perfect surfaces which can provoke specific cellular responses and direct new tissue regeneration. The improvement in biocompatibility of biomaterials for tissue engineering by directed surface modification is an important contribution to biomaterials development. Among many biomaterials used for tissue engineering, polyesters have been well documented for their excellent biodegradability, biocompatibility and nontoxicity. However, poor hydrophilicity and the lack of natural recognition sites on the surface of polyesters have greatly limited their further application in the tissue engineering field. Therefore, how to introduce functional groups or molecules to polyester surfaces, which ideally adjust cell/tissue biological functions, becomes more and more important. In this review, recent advances in polyester surface modification and their applications are reviewed. The development of new technologies or methods used to modify polyester surfaces for developing their biocompatibility is introduced. The results of polyester surface modifications by surface morphological modification, surface chemical group/charge modification, surface biomacromolecule modification and so on are reported in detail. Modified surface properties of polyesters directly related to in vitro/vivo biological performances are presented as well, such as protein adsorption, cell attachment and growth and tissue response. Lastly, the prospect of polyester surface modification is discussed, especially the current conception of biomimetic and molecular recognition.

In this paper, a kind of core-shell composite microsphere was prepared based on poly(Nisopropylacrylamide-co-methacrylic acid) (P(NIPAM-co-MAA)) coated magnetic mesoporous silica nanoparticles (M-MSN) via precipitation polymerization. The composite microsphere presented a thermo/pH-coupling sensitivity and the volume phase transition could be precisely regulated by the molar ratio of MAA to NIPAM or the concentration of NaCl. At physiological conditions (37 C, 0.15 M NaCl), the P(NIPAM-co-MAA) shell underwent a distinct transition from a swollen state in pH 7.4 to a collapsed state in pH 5.0, so that the polymer shell was active in moderating the diffusion of embedded drugs in-and-out of the pore channels of MSN. Doxorubicin hydrochloride (DOX) was applied as a model drug and the behaviors of drug storage/release were investigated. The drug loaded behavior was pH-dependent, and the composite microsphere had a drug embed efficiency of about 91.3% under alkaline conditions. The cumulative in vitro release of the DOX-loaded composite microsphere showed a low level of leakage below the volume phase transition temperature (VPTT) and was significantly enhanced above its VPTT, exhibiting an apparent thermo/pH-response controlled drug release. The cytotoxicity assay of a blank carrier to normal cells indicated that the composite microspheres were suitable as drug carriers, while the DOX-loaded composite microspheres had a similar cytotoxicity to HeLa cells compared with free DOX. Therefore, the thermo/pH-sensitive composite microsphere could, in principle, be used for in vivo cancer therapy with a low premature drug release during blood circulation whilst having a rapid release upon reaching tumor tissues.