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The structural and magnetic properties of Bi0.5La0.5Fe1−xCrxO3−δ (x = 0, 0.05, 0.10, 0.20, and 0.40) compounds synthesized by a solid-state reaction method have been investigated. Rietveld refinement of x-ray and neutron powder diffraction data revealed a nonpolar orthorhombically distorted perovskite Pnma structure with long-range G-type antiferromagnetic (AFM) order in the studied samples. It was observed that substitution by Cr strongly influenced the morphology, crystalline, and magnetic properties of the samples. Interestingly, Cr doping led to an abrupt increase in the crystallite size from 31 nm for x = 0 to 740 nm for x = 0.40. This size change was accompanied by a decrease of microstrain by about twofold and a sudden change of the structural parameters. Magnetization measurements indicated the coexistence of ferromagnetic (FM) clusters with long-range AFM order. It was established that Cr doping leads to a suppression of the magnetic states. More interestingly, all of the samples demonstrated a spontaneous large exchange bias (EB) effect at room temperature, which is of great interest from the viewpoint of practical applications. The EB effect originates from pinning of uncompensated spins at the interfaces between FM clusters and the AFM matrix.

Platinum complexes have paid much attention to develop new drugs for cancer therapy due to its inhibitory activity against cancerous cell growth. In the study, the strategically programming cationic PAMAM G4.0 with carboxylate motifs was introduced as a delivery platform for cisplatin. Partial amino groups on the surface of PAMAM G4.0 had coupled with active carboxylate groups on polyacrylic acid (PAA) in order to reduce the remaining problem of cationic dendrimer and improve delivery effectiveness of aquated cisplatin. Our results show that the full cationic PAMAM G4.0 was toxic against both breast cancer (MCF7) and human dermal fibroblast (HuDF) cell lines at 100 ppm concentration. In the contract, the PAA-conjugated PAMAM G4.0 significantly improved their cytocompatibility of the cationic dendrimer. In addition, the modified PAMAM dendrimers G4.0 showed high affinity with the aquated cisplatin due to the presence of abundant carboxylic groups. Notably, the aquated cisplatin-complexed PAA-G4.0 showed 2.94-folded reduction in the toxicity against NCI H460 in comparison to free cisplatin drugs. Hence, the G4.0-PAA/aquated cisplatin nano-complex may become a promising versatile strategy for improving antitumour efficacy and reducing the side effects of platinum-based drugs.

To utilize the potent pharmaceutical properties of curcumin (Cur) and gelatin-based materials in tissue regeneration, we fabricated a thermosensitive nanocomposite hydrogel based on pluronic-grafted gelatin (PG) and nanocurcumin (nCur) to enhance burn healing. In this method, the amphiphilic PG played a role as a surfactant to prepare and protect nanosized Cur particles, which could overcome the poor dissolution of the phytochemical. The synthesized PG was identified by $$^{1}\hbox {H}$$ nuclear magnetic resonance. Depending on the amount of Cur, size distribution of the dispersed nCur ranged from 1.5 ± 0.5 to 16 ± 3.2 nm as observed using transmission electron microscopy and dynamic light scattering. The nCur-dispersed PG solution formed nCur–PG nanocomposite hydrogel on warming up to $$35{^{\circ }}\hbox {C}$$ . Release profile indicated sustainable release of Cur from the injectable platform. Fibroblast cells were well proliferated on the nanocomposite hydrogel. The nCur–PG enhanced the healing process of second-degree burn wound. These results showed potential applications of the biomaterial in tissue regeneration.

Nano-carriers are not only evaluated as a novel kind of drug delivery, but also expected to bypass the critical bottleneck of conventional cancer chemotherapeutics. Among them, thermo-sensitive nanogel draws much attention due to its efficacy in the loading and release of hydrophobic drugs. In the study, we developed a promising thermosensitive polymer-grafted dendrimer to enhance drug-loading efficiency, which was prepared from conjugation of thermo-sensitive carboxylic-terminated poly(N-isopropylacrylamide) polymer (PNIPAM) with polyamidoamine (PAMAM) dendrimer (G3.0). The obtained copolymer structure and molecular weight were confirmed by proton nuclear magnetic resonance ( 1 H NMR) and gel permeation chromatography (GPC), respectively. Morphology of the nanocarrier was observed around 120–150 nm by transmission electron microscopy (TEM) and 200 nm by dynamic light scattering (DLS). The nanocarrier exhibited the higher drug loading (DL = 7.79%) and entrapment efficiency (EE = 42.25%) of 5-FU compared to PAMAM dendrimer G3.0 (DL = 2.25% and EE = 11.52%). In-vitro test, the 5-FU-loaded in PAMAM G3.0–PNIPAM could release approximately 40% of the encapsulated drug at pH = 7.4 after 5 days tracking, while the cumulative anticancer drugs achieved nearly two-fold increase (around 75%) at pH 5.5 during the same time. Moreover, the cytotoxicity assay results also indicated that the drug-loaded nanocarrier exhibited a significant growth inhibition of the MCF-7 cancer cell. The obtained resulted possibly offered a great potential of the nanocarrier which may be utilized in delivering other anticancer drugs or dual drugs for chemotherapy in future.

Gelatin hydrogels have recently attracted much attention for tissue regeneration because of their biocompatibility. In this study, we introduce poly-ethylene glycol (PEG)—grafted gelatin containing tyramine moieties which have been utilized for in situ enzyme-mediated hydrogel preparation. The hydrogel can be used to load nanoparticles of biphasic calcium phosphate, a mixture of hydroxyapatite and β-tricalcium phosphate, and forming injectable bio-composites. Proton nuclear magnetic resonance (1H NMR) spectra indicated that tyramine-functionalized polyethylene glycol-nitrophenyl carbonate ester was conjugated to the gelatin. The hydrogel composite was rapidly formed in situ (within a few seconds) in the presence of horseradish peroxidase and hydrogen peroxide. In vitro experiments with bio-mineralization on the hydrogel composite surfaces was well-observed after 2 weeks soaking in simulated body fluid solution. The obtained results indicated that the hydrogel composite could be a potential injectable material for bone regeneration.

In this paper, we report the preparation and stabilization of colloidal silver nanoparticle solution, with the assistance of chitosan dihydroxyphenyl acetamide (CDHPA), or oligochitosan dihydroxyphenyl acetamide (OCDHPA). The structure of the chitosan derivatives were characterized by nuclear magnetic resonance (1H NMR) spectroscopy. The morphology of the synthesized silver core-chitosan shell nanoparticles were observed by transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques, and showed a well-defined core-shell structure of polymer-coated silver nanoparticles (AgNPs). The core-shell NPs exhibited a strong antibacterial activity against E. coli and S. aureus, at a very low concentration of AgNPs (2.5 ppm). Our studies offer a new method for the preparation and protection of silver nanoparticles for antibacterial applications. Open image in new window

In this study, a bioactive hydrogel was prepared from a chitosan derivative and Arg-Gly-Asp (RGD)-conjugated polypseudorotaxane, which is a cell-adhesive extracellular matrix. Chitosan was modified with 4-hydroxy phenyl acetic acid to obtain a water-soluble product for enzymatic cross-linking. Tyramine-terminated polypseudorotaxane (PRx) was prepared from the inclusion complex of a tyramine-terminated poly(ethylene glycol) backbone, and α-cyclodextrin (α-CD). Gly-Arg-Gly-Asp-Ser (GRGDS) was conjugated to the PRx using 4-nitrophenyl chloroformate (NPC) and partially carboxylated with succinic anhydride. The structure of the PRx-RGD and 4-hydroxylphenylacetamide chitosan (CHPA) was characterized by 1H NMR and FTIR spectroscopy. The RGD content in PRx-RGD was determined to be 0.19%. PRx-RGD and CHPA solution was crosslinked to form a bioactive hydrogel in the presence of horseradish peroxidase (HRP) and hydrogen peroxide (H2O2), which exhibited rapid gelation (∼20 sec). An in vitro cell culture was carried out with L929 mouse fibroblasts for 1 and 3 days. The results showed that fibroblasts adhered better and appeared to be more biocompatible on the RGD-conjugated hydrogel than the hydrogel without RGD. The combined results highlight the potential use of this bioactive hydrogel as an injectable scaffold in tissue engineering applications. Open image in new window

Star-shaped poly(methyl acrylate) (PMA) was synthesized using tri(2-bromopropionate) glyceride as the initiator and methyl acrylate as the monomer via atom transfer radical polymerization (ATRP). The structures of tri(2-bromopropionate) glyceride and PMA were characterized by IR, GC-MS, 1H NMR, and 13C NMR. The reinforcing effects of this star-shaped PMA on polyvinylchloride (PVC) in various PMA/PVC blends were evaluated. The results indicated that a blend containing 1% star-shaped PMA exhibits an 18% increase in the elastic modulus and a 10% increase in tensile strength compared to PVC. Moreover, the impact resistance of the blend was 30% higher than that for PVC. The blend also exhibited high thermal stability. SEM images showed that the star-shaped PMA and PVC are highly compatible when blended, which causes the enhanced elasticity of the blend.