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It was necessary to study the bonding mechanism of poly(D,L-lactide) (PDLLA) and hydroxyapatite (HA) nanoparticles because of their increasing application in medical fields. In this paper, hydrogen bonding between PDLLA and HA in PDLLA/HA nanocomposites was first investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Structural morphology and glass transition temperature (T g ) of the nanocomposites showed that there was a close interaction between polymer matrix and inorganic nanoparticls. The results from FTIR and XPS indicated that the hydrogen bonding between the CdO in PDLLA and the surface PsOH groups of HA nanocrystalline was formed indeed. Shape memory properties were improved, which further implied the existence of hydrogen bonding in these nanocomposites. Thus, we designed a schematic model of the hydrogen bonding on the base of the experimental results. It can clearly explain the interaction mechanism of polymeric phases and inorganic phase in nanocomposites.

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In this study, we developed a thermoresponsive and water-responsive shape-memory polymer nanocomposite network by chemically cross-linking cellulose nanocrystals (CNCs) with polycaprolactone (PCL) and polyethylene glycol (PEG). The nanocomposite network was fully characterized, including the microstructure, cross-link density, water contact angle, water uptake, crystallinity, thermal properties, and static and dynamic mechanical properties. We found that the PEG[60]-PCL[40]-CNC[10] nanocomposite exhibited excellent thermo-induced and water-induced shape-memory effects in water at 37 °C (close to body temperature), and the introduction of CNC clearly improved the mechanical properties of the mixture of both PEG and PCL polymers with low molecular weights. In addition, Alamar blue assays based on osteoblasts indicated that the nanocomposites possessed good cytocompatibility. Therefore, this thermoresponsive and water-responsive shape-memory nanocomposite could be potentially developed into a new smart biomaterial.

A size changeable polymer micelle system with a dual shell, which increases in size under acidic pH conditions and is altered to smaller micelles, triggered by intracellular glutathione (GSH), is successfully developed. It is capable of direct delivering anticancer drugs to the nucleus of multidrug resistance (MDR) tumor cells for highly effective combating of drug resistant breast cancer.

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Nanocarriers have attracted broad attention in cancer therapy because of their ability to carry drugs preferentially into cancer tissue, but their application is still limited due to the systemic toxicity and low delivery efficacy of intravenously delivered chemotherapeutics. In this study, we develop a localized drug delivery device with combination of an active-targeting micellar system and implantable polymeric nanofibers. This device is achieved first by the formation of hydrophobic doxorubicin (Dox)-encapsulated active-targeting micelles assembled from a folate-conjugated PCL-PEG copolymer. Then, fabrication of the core-shell polymeric nanofibers is achieved with coaxial electrospinning in which the core region consists of a mixture of poly(vinyl alcohol) and the micelles and the outer shell layer consists of cross-linked gelatin. In contrast to the systematic administration of therapeutics via repeatedly intravenous injections of micelles, this implantable device has these capacities of greatly reducing the drug dose, the frequency of administration and side effect of chemotherapeutic agents while maintaining highly therapeutic efficacy against artificial solid tumors. This micelle-based nanofiber device can be developed toward the next generation of nanomedicine for efficient and safe cancer therapy.