Full-Color and Switchable Circularly Polarized Light from a Macroscopic Chiral Dendritic Film through a Solid-State Supramolecular Assembly.

Chiral materials displaying chirality across multiple length scales have attracted increasing interest due to their potential applications in diverse fields. Herein, we report an efficient approach for the construction of macroscopic crystal dendrites with hierarchical chirality based on an in situ solid assembly in a block copolymer film. Chiral fluorescent crystals are formed by enantiopure d-/l-dibenzoyl tartaric acid and pyrenecarboxylic acid in a poly(1,4-butadiene)-b-poly(ethylene oxide) film. The chiro-optical activity of the crystalline dendrites can be greatly amplified in the absorption and scattering regions and goes along with the dimension of dendrites. Notably, the chiral dendrites exhibited strong circularly polarized luminescence emission with a high dissymmetric factor (0.03). The enhancement of the quantum yield of the chiral film was up to 28%, which was 14 times higher that of the corresponding fluorescent molecules. The circularly polarized emission bands of the films can be fine-tuned by contriving the emissive bands of fluorescent molecules. More importantly, the chiral signals are able to be wiped when the fluorescent group photodimerizes under UV irradiation. This work provides an efficient way to develop functional materials through solid self-assembly.

Silver-hydroxyapatite nanocomposites prepared by three sequential reaction steps in one pot and their bioactivities in vitro.

Hydroxyapatite (HA) combined with antimicrobial agents for biomedical application can effectively avoid the bacteria infection, while HA have the good performance. In this study, we prepared silver-hydroxyapatite (Ag-HA) nanocomposites using a one-pot method consisting of three sequential steps of wet chemical precipitation, ion exchange, and a silver mirror reaction. The HA nanoparticles used as the precursor for Ag ion doping were first synthesised by wet chemical precipitation. Next, Ag+ absorbed on HA surface through ion exchange reaction. Glucose was then added to initiate the silver mirror reaction, which made the Ag+ ions reduce to Ag0 and Ag nanoparticles in situ formed on HA nanoparticles. Subsequently, Ag-HA nanocomposites with different Ag content were prepared. X-ray diffraction, SEM, EDX mapping and TEM imaging confirmed that spherical Ag nanoparticles ~20-40 nm in diameter were adhered to the surface of HA nano-rods (0.4-0.8 µm in length and 15-40 nm in diameter). The Ag content (1.9-15.2 wt%) in the Ag-HA nanocomposites was adjusted by varying the feeding Ag/Ca molar ratio (2.0-20%). The cell viability evaluation in vitro proved that Ag-HA nanocomposites had low cytotoxicity to L929 normal cells. Meanwhile, the antibacterial examinations in vitro demonstrated that Ag-HA nanocomposites had obvious antibacterial effects on Gram-positive bacteria, Gram-negative bacteria, and fungus. The antibacterial results were dose-dependent on the accumulation of silver content. The Ag-HA nanocomposites loaded PMMA resins also demonstrated a potential antibacterial activity against S. mutans. This paper presents a convenient and bio-friendly approach for preparing Ag-HA nanocomposites with adjustable Ag content, which are a promising material for biomedical applications.

Hydroxyapatite-Bovine Serum Albumin-Paclitaxel Nanoparticles for Locoregional Treatment of Osteosarcoma.

Osteosarcoma is the most primary type of bone tumor occurring in the pediatric and adolescent age groups. In order to obtain the most appropriate prognosis, both tumor recurrence inhibition and bone repair promotion are required. In this study, a ternary nanoscale biomaterial/antitumor drug complex including hydroxyapatite (HA), bovine serum albumin (BSA) and paclitaxel (PTX) is prepared for post-surgical cancer treatment of osteosarcoma in situ. The HA-BSA-PTX nanoparticles, about 55 nm in diameter with drug loading efficiency (32.17 wt%), have sustained release properties of PTX and calcium ions (Ca2+ ) and low cytotoxicity to human fetal osteoblastic (hFOB 1.19) cells in vitro. However, for osteosarcoma (143B) cells, the proliferation, migration, and invasion ability are significantly inhibited. The in situ osteosarcoma model studies demonstrate that HA-BSA-PTX nanoparticles have significant anticancer effects and can effectively inhibit tumor metastasis. Meanwhile, the detection of alkaline phosphatase activity, calcium deposition, and reverse transcription-polymerase chain reaction proves that the HA-BSA-PTX nanoparticles can promote the osteogenic differentiation. Therefore, the HA-BSA-PTX nanodrug delivery system combined with sustained drug release, antitumor, and osteogenesis effects is a promising agent for osteosarcoma adjuvant therapy.

Development of a multifunctional gold nanoplatform for combined chemo-photothermal therapy against oral cancer.

Aim: To design and fabricate a multifunctional drug-delivery nanoplatform for oral cancer therapy. Materials & methods: Polyethylene glycol-stabilized, PDPN antibody (PDPN Ab)- and doxorubicin (DOX)-conjugated gold nanoparticles (AuNPs) were prepared and evaluated for their cytotoxicity and antitumor efficacy in both chemotherapy and photothermal therapy. Results: The obtained (PDPN Ab)-AuNP-DOX system presents low toxicity, a high drug loading capacity and cellular uptake efficiency. Both in vitro and in vivo experiments demonstrate that (PDPN Ab)-AuNP-DOX has enhanced antitumor efficacy. Treatment with (PDPN Ab)-AuNP-DOX combined with laser irradiation exhibits superior antitumor effects. Conclusion: This (PDPN Ab)-AuNP-DOX system may be used as a versatile drug-delivery nanoplatform for targeted and combined chemo-photothermal therapy against oral cancer.

Proteoglycan 4 predicts tribological properties of repaired cartilage tissue.

Purpose: One of the essential requirements in maintaining the normal joint motor function is the perfect tribological property of the articular cartilage. Many cartilage regeneration strategies have been developed for treatment in early stages of osteoarthritis, but there is little information on how repaired articular cartilage regains durability. The identification of biomarkers that can predict wear resistant property is critical to advancing the success of cartilage regeneration therapies. Proteoglycan 4 (PRG4) is a macromolecule distributing on the chondrocyte surface that contributes to lubrication. In this study, we investigate if PRG4 expression is associated with tribological properties of regenerated cartilage, and is able to predict its wear resistant status. Methods: Two different strategies including bone marrow enrichment plus microfracture (B/BME-MFX) and microfracture alone (B-MFX) of cartilage repair in sheep were used. PRG4 expression and a series of tribological parameters on regenerated cartilage were rigorously examined and compared. Results: Highly and continuously expression of PRG4 in regenerated cartilage surface was negatively correlated with each tribological parameter (P<0.0001, respectively). Multivariate analysis showed that PRG4 expression was the key predictor that contributed to the promotion of cartilage wear resistance. Conclusion: Higher PRG4 expression in regenerated cartilage is significantly associated with wear resistance improvement. PRG4 may be useful for predicting the wear resistant status of regenerated cartilage and determining the optimal cartilage repair strategy.

Chlorin e6 and polydopamine modified gold nanoflowers for combined photothermal and photodynamic therapy.

Combinational photo-based approaches with enhanced efficacy for cancer therapy have garnered increasing attention in recent years. In this work, a multifunctional system for synergistic photothermal and photodynamic cancer therapy was successfully prepared. The system consists of gold nanoflowers (AuNFs) conjugated with Chlorin e6 (Ce6), and then coated with a polydopamine (PDA) layer. AuNFs with diameters around 80 nm and a broad absorbance in the visible-near infrared (Vis-NIR) range of 500 to 800 nm, were successfully synthesized by a two-step process at 0 °C, using HAuCl4, ascorbic acid (AA), and hydroxylamine hydrochloride (NH2OH·HCl) as the reactants. Glutathione (GSH) molecules chemically anchored to the gold surfaces were used to provide addressable sites for Ce6 conjugated to GSH-AuNFs through an amidation reaction. A PDA layer was then wrapped outside the Ce6-GSH-AuNFs via self-polymerization of dopamine, which provided additional chemical modification and functionalization. Finally, the multifunctional PDA-Ce6-GSH-AuNFs were obtained. The content of Ce6 incorporated into the AuNFs was 14.0 wt%, and the singlet oxygen yield of PDA-Ce6-GSH-AuNFs was approximately 91.0% of that of free Ce6. PDA-Ce6-GSH-AuNFs showed better photothermal conversion efficiency (η = 23.6%), lower cytotoxicity, and faster cell internalization. Both in vitro and in vivo investigation of the combined treatment with a near-infrared (NIR) laser (660 nm for photodynamic therapy, and 808 nm for photothermal therapy) demonstrated that PDA-Ce6-GSH-AuNFs had excellent phototoxicity and synergistic effects of killing cancer cells. Hence, PDA-Ce6-GSH-AuNFs are a dual phototherapeutic agent that exhibits photodynamic and photothermal therapeutic effects and has potential application in enhanced cancer therapy.

An enzyme-responsive membrane for antibiotic drug release and local periodontal treatment.

Periodontitis is a chronic, destructive inflammatory disease that injures tooth- supporting tissues, eventually leading to tooth loss. Complete eradication of periodontal pathogenic microorganisms is fundamental to allow periodontal healing and commonly precedes periodontal tissue regeneration. To address this challenge, we report a strategy for developing an enzyme-mediated periodontal membrane for targeted antibiotic delivery into infectious periodontal pockets; the unique components of the membrane will also benefit periodontal alveolar bone repair. In this approach, a chitosan membrane containing polyphosphoester and minocycline hydrochloride (PPEM) was prepared. Physical, morphological, and ultrastructural analyses were carried out in order to assess cellular compatibility, drug release and antibacterial activity in vitro. Additionally, the functionality of the PPEM membrane was evaluated in vivo with a periodontal defect model in rats. The results confirm that the PPEM membrane exhibits good physical properties with excellent antibacterial activity and successfully promotes periodontal tissue repair, making it promising for periodontal treatment.

Biodegradable Cyclomatrix Polyphosphazene Nanoparticles: A Novel pH-Responsive Drug Self-Framed Delivery System.

Traditional drug delivery systems suffer from low drug-loading and relatively weak therapeutic efficacy, therefore, development of new drug delivery systems with high-efficiency has become more urgent. In this report, a novel-innovative drug delivery strategy, namely drug self-framed delivery system (DSFDS), is prepared via using anticancer drugs as polymer frame without using any carriers. The drug molecules (exemplified by doxorubicin) containing more than two nucleophilic functional groups (diols/diamines) directly reacted with hexachlorocyclotriphosphazene via mild precipitation polycondensation under ambient conditions, forming biocompatible drug self-framed delivery nanoparticles. Because of the covalent bonding of the drug molecules, DSFD nanoparticles (DSFDs) with super high drug-loading were stable in the circulation during delivery. However, sustained release of drug in the acidic environment within cells endowed DSFDs with long-term anticancer therapeutic efficacy. This strategy is applicable for diverse hydrophilic and hydrophobic drugs and may be a new platform for designing high drug-loading and release-controllable drug delivery systems.

Paclitaxel/Chitosan Nanosupensions Provide Enhanced Intravesical Bladder Cancer Therapy with Sustained and Prolonged Delivery of Paclitaxel.

Bladder cancer (BC) is a very common cancer. Nonmuscle-invasive bladder cancer (NMIBC) is the most common type of bladder cancer. After postoperative tumor resection, chemotherapy intravesical instillation is recommended as a standard treatment to significantly reduce recurrences. Nanomedicine-mediated delivery of a chemotherapeutic agent targeting cancer could provide a solution to obtain longer residence time and high bioavailability of an anticancer drug. The approach described here provides a nanomedicine with sustained and prolonged delivery of paclitaxel and enhanced therapy of intravesical bladder cancer, which is paclitaxel/chitosan (PTX/CS) nanosupensions (NSs). The positively charged PTX/CS NSs exhibited a rod-shaped morphology with a mean diameter about 200 nm. They have good dispersivity in water without any protective agents, and the positively charged properties make them easy to be adsorbed on the inner mucosa of the bladder through electrostatic adsorption. PTX/CS NSs also had a high drug loading capacity and can maintain sustained release of paclitaxel which could be prolonged over 10 days. Cell experiments in vitro demonstrated that PTX/CS NSs had good biocompatibility and effective bladder cancer cell proliferation inhibition. The significant anticancer efficacy against intravesical bladder cancer was verified by an in situ bladder cancer model. The paclitaxel/chitosan nanosupensions could provide sustained delivery of chemotherapeutic agents with significant anticancer efficacy against intravesical bladder cancer.

Microplastics in freshwater river sediments in Shanghai, China: A case study of risk assessment in mega-cities.

Microplastics, which are plastic debris with a particle diameter of less than 5 mm, have attracted growing attention in recent years. Its widespread distributions in a variety of habitats have urged scientists to understand deeper regarding their potential impact on the marine living resources. Most studies on microplastics hitherto are focused on the marine environment, and research on risk assessment methodology is still limited. To understand the distribution of microplastics in urban rivers, this study investigated river sediments in Shanghai, the largest urban area in China. Seven sites were sampled to ensure maximum coverage of the city's central districts, and a tidal flat was also included to compare with river samples. Density separation, microscopic inspection and µ-FT-IR analysis were conducted to analyze the characteristics of microplastics and the type of polymers. The average abundance of microplastics in six river sediment samples was 802 items per kilogram of dry weight. The abundance in rivers was one to two orders of magnitude higher than in the tidal flat. White microplastic spheres were most commonly distributed in river sediments. Seven types of microplastics were identified, of which polypropylene was the most prevailing polymers presented. The study then conducted risk assessment of microplastics in sediments based on the observed results, and proposed a framework of environmental risk assessment. After reviewing waste disposal related legislation and regulations in China, this study conclude that in situ data and legitimate estimations should be incorporated as part of the practice when developing environmental policies aiming to tackle microplastic pollution.

Antibacterial activity, cytotoxicity and mechanical behavior of nano-enhanced denture base resin with different kinds of inorganic antibacterial agents.

Silanized aluminum borate whiskers (ABWs) of 4 wt%, silanized zirconium dioxide nanoparticles (nano-ZrO2) of 2 wt% were mixed with polymethyl methacrylate (PMMA) powder to get ZrO2-ABWs/PMMA composites. Titanium dioxide (TiO2), silver-supported titanium dioxide (Ag/TiO2), silver-supported zirconium phosphate (Novaron) and tetrapod-like zinc oxide whiskers (T-ZnOw) antibacterial agents of 3 wt% were mixed with ZrO2-ABWs/PMMA composites respectively to fabricate standard specimens. Plaque biofilms on the specimens surface were investigated for colony-forming units (CFUs). In addition, cytotoxicity and mechanical behavior were evaluated. Results showed that the CFUs values of S. mutans and C. albican biofilms on the four antibacterial composites surface were all reduced (p<0.05) compared to the blank and control groups. The antibacterial composites did not have an adverse effect on fibroblast growth in this study (p>0.05) except TiO2 and Ag/TiO2 groups of undiluted extracts. The flexural strength and surface hardness of Novaron and T-ZnOw groups were increased (p<0.05) compared to the control group.

Microplastics in sediments of the Changjiang Estuary, China.

Microplastics are plastics that measure less than 5 mm in diameter. They enter the marine environment as primary sources directly from industrial uses, as well as secondary sources resulting from the degradation of large plastic debris. To improve the knowledge of microplastic pollution in China, we investigated samples from 53 estuarine sediment locations collected with a box corer within the Changjiang Estuary. Microplastics (<5 mm) were extracted from sediments by density separation, after which they were observed under a microscope and categorized according to shape, color and size. Identification was carried out using Micro-Fourier-Transform Infrared Spectroscopy (µ-FT-IR). The abundance of microplastics in the Changjiang Estuary was mapped. The mean concentration was 121 ± 9 items per kg of dry weight, varying from 20 to 340 items per kg of dry weight. It was found that the concentration of microplastics was the highest on the southeast coast of Shanghai. The distribution pattern of microplastics may be affected by the Changjiang diluted water in summer. All of the microplastics collected were categorized according to shape, color and size. Among which fiber (93%), transparent (42%) and small microplastics (<1 mm) (58%) were the most abundant types. No clear correlation between microplastics and the finer sediment fraction was found. Rayon, polyester, and acrylic were the most abundant types of microplastics identified, indicating that the main source of microplastics in the Changjiang Estuary was from washing clothes (the primary source). It is possible to compare microplastic abundance in this study with the results of other related studies using the same quantification method. The identification of microplastics raises the awareness of microplastic pollution from drainage systems. The prevalence of microplastic pollution calls for monitoring microplastics at a national scale on a regular basis.

Micro-/nanofibers prepared via co-assembly of paclitaxel and dextran.

In this paper, we reported the preparation of micro-/nanofibers via co-assembly with paclitaxel (PTX) and dextran (DEX). The co-assembly fibers formed in PTX and DEX mixture solution via non-covalent interactions including hydrophilic/hydrophobic interactions and π-π stacking. The micro-/nanofibers could be obviously observed when the mixed solution became turbid and ivory-white in color. The properties of fibers were characterized by SEM, TEM, FTIR, DSC, XRD, in vitro release and MTT assay. The length of fibers could reach several centimeters. The diameter of microfibers and nanofibers was about 800nm and 80nm, respectively. In addition, the PTX loading efficiency was over 78% in co-assembly fibers and up to 84% when PTX and DEX (Mw: 40,000) both were 2mg/mL. The sustained drug release and low cytotoxicity in vitro of PTX/DEX fibers were also demonstrated. Therefore, we believe that PTX/DEX micro-/nanofibers would have great potential for drug delivery of PTX.

Water soluble and insoluble components of urban PM2.5 and their cytotoxic effects on epithelial cells (A549) in vitro.

When PM2.5 enters human bodies, the water soluble (WS-PM2.5) and insoluble components (WIS-PM2.5) of PM2.5 would interact with cells and cause adverse effects. However, the knowledge about the individual toxicity contribution of these two components is limited. In this study, the physiochemical properties of PM2.5 were well characterized. The toxic effects of WS-PM2.5 and WIS-PM2.5, which include the cell viability, cell membrane damage, reactive oxygen species (ROS) generation and morphological changes, were examined with human lung epithelial A549 cells in vitro. The results indicated that WS-PM2.5 could induce the early response of ROS generation, multiplied mitochondria and multi-lamellar bodies in A549 cells, which might cause cell damage through oxidative stress. Meanwhile, WIS-PM2.5 was predominantly associated with the cell membrane disruption, which might lead to the cell damage through cell-particle interactions. Moreover, the synergistic cytotoxic effects of WS-PM2.5 and WIS-PM2.5 were observed at longer exposure time. These findings demonstrate the different cytotoxicity mechanisms of WS-PM2.5 and WIS-PM2.5, which suggest that not only the size and dosage of PM2.5 but also the solubility of PM2.5 should be taken into consideration when evaluating the toxicity of PM2.5.

Toward Scalable Fabrication of Hierarchical Silica Capsules with Integrated Micro-, Meso-, and Macropores.

Hierarchical porous structures are ubiquitous in biological organisms and inorganic systems. Although such structures have been replicated, designed, and fabricated, they are often inferior to naturally occurring analogues. Apart from the complexity and multiple functionalities developed by the biological systems, the controllable and scalable production of hierarchically porous structures and building blocks remains a technological challenge. Herein, a facile and scalable approach is developed to fabricate hierarchical hollow spheres with integrated micro-, meso-, and macropores ranging from 1 nm to 100 µm (spanning five orders of magnitude). (Macro)molecules, micro-rods (which play a key role for the creation of robust capsules), and emulsion droplets have been successfully employed as multiple length scale templates, allowing the creation of hierarchical porous macrospheres. Thanks to their specific mechanical strength, these hierarchical porous spheres could be incorporated and assembled as higher level building blocks in various novel materials.

Amorphous carbon dots with high two-photon fluorescence for cellular imaging passivated by hyperbranched poly(amino amine).

Amorphous carbon dots (C-Dots) with high two-photon fluorescence were prepared by using citric acid (CA) as the carbon source and hyperbranched poly(amino amine) (HPAA) as the surface passivation agent through a facile hydrothermal approach. The C-Dots with an average diameter about 10 nm were readily dispersed in water. They exhibited excellent fluorescence properties and excitation-dependent fluorescence behavior with the corresponding quantum yield (QY) of 17.1% in aqueous solution. Interestingly, the C-Dots emitted bright fluorescence even in the solid state with a QY of 16.3%, which is the highest value obtained for carbon-based nanomaterials. Using the MTT assay, the C-Dots showed low cytotoxicity against L929 normal cells. Furthermore, they were easily internalized by HeLa cells and presented high quality one- and two-photon cellular imaging, suggesting significant potential for application in biological imaging.

Physiochemical properties and bioapplication of nano- and microsized hydroxy zinc phosphate particles modulated by reaction temperature.

We investigated the effect of reaction temperature on the particle size and morphology of hydroxy zinc phosphate particles (HZnPPs). The influence of differences in shape on the physiochemical properties of HZnPPs and the possible bioapplications of these particles were also investigated. HZnPPs with both hollow and solid nanospheres and microsized rectangular sheet-like particles were successfully prepared by a wet chemical method using Zn (NO3)2·6H2O and (NH4)2HPO4 as the reactants and ammonia to adjust the pH. The synthesis was performed at temperatures ranging from 0 to 95 °C. The particle size, morphology, crystal structure and thermal properties were analysed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, the Brunauer-Emmett-Teller specific surface area, thermogravimetric analysis and dynamic light scatting. The chemical composition and vibrational spectra were measured using inductively coupled plasma atomic emission spectrometry, Fourier transform infrared spectrometry and Raman spectrometry. The transmission electron microscopy results showed that a hollow spherical structure with a pore size of 20-30 nm was obtained at reaction temperatures <25 °C. With increasing temperature, the nanoparticles changed from hollow to solid spheres of a similar size. Microsized rectangular sheet-like particles were formed when the reaction temperature was >60 °C. The effect of HZnPPs on cell viability in vitro was evaluated by the MTT assay against normal NIH/3T3 cells. The hollow and solid nanospheres had a lower cell cytotoxicity than the microsized sheet-like particles. Both the nanospheres and the rectangular sheet-like particles were able to adsorb heavy metal ions. The hollow nanospheres were also used as a carrier for a high drug-loading of epirubicin. These results clearly show that temperature plays an important part in regulating the nanoscale hierarchical structure of HZnPPs and their properties.

Sequential release of autophagy inhibitor and chemotherapeutic drug with polymeric delivery system for oral squamous cell carcinoma therapy.

Autophagy inhibition is emerging as a new paradigm for efficient cancer therapy by overcoming multidrug resistance (MDR). Here, we developed an effective chemotherapeutic system for oral squamous cell carcinoma (OSCC) based on polymeric nanomicelles for codelivery of the anticancer drug doxorubicin (DOX) and the autophagy inhibitor LY294002 (LY). The hydrophobic DOX was conjugated onto a hydrophilic and pH-responsive hyperbranched polyacylhydrazone (HPAH), forming the DOX-conjugated HPAH (HPAH-DOX). Due to its amphiphilicity, HPAH-DOX self-assembled into nanomicelles in an aqueous solution and the autophagy inhibitor LY could be loaded into the HPAH-DOX micelles. The release of DOX and LY from the LY-loaded HPAH-DOX micelles was pH-dependent, whereas LY was released significantly faster than DOX at a mildly acidic condition. The in vitro evaluation demonstrated that the LY-loaded HPAH-DOX micelles could rapidly enter cancer cells and then release LY and DOX in response to an intracellular acidic environment. Compared to the HPAH-DOX micelles and the physical mixture of HPAH-DOX and LY, the LY-loaded HPAH-DOX micelles induced a higher proliferation inhibition of tumor cells, illustrating a synergistic effect of LY and DOX. The preferentially released LY inhibited the autophagy of tumor cells and made them more sensitive to the subsequent liberation of DOX. The polymeric codelivery system for programmable release of the chemotherapy drug and the autophagy inhibitor provides a new platform for combination of traditional chemotherapy and autophagy inhibition.

Hybrid effects of zirconia nanoparticles with aluminum borate whiskers on mechanical properties of denture base resin PMMA.

The aim of this study was to investigate the hybrid effects of ZrO2 nanoparticles (nano-ZrO2) and aluminum borate whiskers (ABWs) on flexural strength and surface hardness of denture base resin, polymethyl methacrylate (PMMA). Both nano-ZrO2 and ABWs were modified by silane coupling agent (Z6030) before being mixed with PMMA. Various amounts of silanized nano-ZrO2 and ABWs were mixed with PMMA to prepare ZrO2-ABW/PMMA composites. Flexural strength and surface hardness were evaluated using three- point bending test and Vickers hardness test respectively. Fractured surfaces were also observed by scanning electron microscopy (SEM). The mechanical behaviors of silanized ZrO2-ABW/PMMA composites were significantly improved. Flexural strength reached a maximum value of 108.01 ± 5.54 MPa when 2 wt% of nano-ZrO2 was mixed with ABWs at a ZrO2/ABW ratio of 1:2, amounting to an increase of 52% when compared with pure PMMA. Surface hardness achieved a maximum value of 22.50 ± 0.86 MPa when 3 wt% of nano-ZrO2 was mixed with ABWs at the same ZrO2/ABW ratio, which was an increase of 27% when compared with pure PMMA.

The potential of pH-responsive PEG-hyperbranched polyacylhydrazone micelles for cancer therapy.

pH-responsive hyperbranched polymers have attracted much attention due to their unique properties for tumor-targeted drug delivery. In this study, we describe a pH-responsive drug carrier, poly (ethylene glycol) (PEG)-hyperbranched polyacylhydrazone (HPAH), which can form nanoscale micelles to be used as anti cancer drug carriers with pH-controlled drug release. The molecular structure of PEG-HPAH was confirmed by nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FTIR). The drug-loaded micelles with a diameter of approximately 190 nm, were prepared using a dialysis method against PBS with a pH of 8.0. The drug-loaded micelles showed the desired pH-dependent drug release properties. The drug release levels were low at neutral and alkaline pH, but increased significantly with a decrease in the pH of the medium. Intracellular uptake results indicated that the PEG-HPAH-drug micelles could efficiently deliver chemotherapeutic drugs into the cells. In addition, it was found that the subcellular localization of the drug-loaded micelles was different from that of free drugs, in which the drug-loaded micelles were mainly in the cytoplasm. The docetaxel (DTX)-loaded PEG-HPAH micelles presented a high cytotoxic activity against tumor cells in vitro. When combined with the administration of glucose, the PEG-HPAH-DTX micelles exhibited a superior anti-tumor efficacy and a lower systemic toxicity in vivo. The biodistribution profile showed increased accumulated drug levels in tumor tissue and plasma in micelles treated group. The results indicate that the nanoscale PEG-HPAH-DTX micelles may serve as a selective tumor-targeting drug delivery system.