Tairong Kuang

Polyelectrolyte/mesoporous silica hybrid materials for the high performance multiple-detection of pH value and temperature

Mesoporous silica nanoparticles have been widely adopted in energy, biology and medicine due to their well-ordered and stable structures. Nevertheless, few attempts have been made to study these materials as a sensing tool. Herein, we report a “smart” sensor for the dual-detection of the pH value and temperature, which was implemented with environmentally responsive polyelectrolyte/mesoporous silica electrodes. Using SBA-15 silica as the framework, we functionalized the internal mesopores with DMAMEA monomer via surface-initiated RAFT polymerization (“grafting-from” method). By controlling the degree of polymerization, the pore size and the specific surface area can be precisely controlled. When the degree of polymerization was optimized to 75, the hybrid material showed significant sensitivity in response to the pH value in the range of 4–10 and optimally responded to the temperature at 39 °C, setting a pH value of 10. The ionic conductivities of the template Fe(CN)64−/3− and Ru(NH3)62+/3+ ions were switchable in different conditions. These results suggest that the polyelectrolyte/mesoporous silica hybrid materials could have potential for application in dual-functional sensors in environmental detection.

Functional exosome-mimic for delivery of siRNA to cancer: in vitro and in vivo evaluation.

Exosomes, the smallest subgroup of extracellular vesicles, have been recognized as extracellular organelles that contain genetic and proteomic information for long distance intercellular communication. Exosome-based drug delivery is currently a subject of intensive research. Here, we report a novel strategy to produce nanoscale exosome-mimics (EMs) in sufficient quantity for gene delivery in cancer both in vitro and in vivo. Size-controllable EMs were generated at a high yield by serial extrusion of non-tumorigenic epithelial MCF-10A cells through filters with different pore sizes. siRNA was then encapsulated into the EMs by electroporation. Biosafety and uptake efficiency of the EMs were evaluated both in vitro and in vivo. The mechanism underlying their cellular endocytosis was also studied.

Effect of nanoporous structure and polymer brushes on the ionic conductivity of poly(methacrylic acid)/anode aluminum oxide hybrid membranes

Anode aluminum oxide (AAO) porous materials have been widely used in ionic translocation for many biological and chemical studies. However, the lack of stimuli-response of this material limits its applications for the precise control of ionic transportation by the external environment. In this study, we functionalized the internal nanopores of AAO membranes to generate polyelectrolyte-filled pH-responsive membranes whose ionic conductivity could be readily controlled by changing the pH value. AAO membranes with different pore sizes (25, 75 and 100 nm) were modified with poly(methacrylic acid) (PMAA) by a “grafting-to” approach. Thermogravimetric and SEM analysis revealed that the extent of PMAA infiltration strongly depends upon the relative sizes of the nanopores and the PMAA concentration. Increasing the size of the nanopores enables the infiltration of PAA solution with a higher concentration. Electrochemical impedance spectroscopy demonstrated that the membrane conductivity decreases from 7.87 × 10−4 S cm−1 at pH 1 to 5.72 × 10−5 S cm−1 at pH 7. The functionalized AAO nanopores showed significant sensitivity to pH value, whereas a valve effect was observed in the pH range between 4 and 5. Our fabricated PMAA-AAO membranes show promising potential to be used as pH sensors and smart valves in micro-/nano-total analysis chips for biomedical and chemical applications.

Molecular Beacon Nano-Sensors for Probing Living Cancer Cells.

Heterogeneities and oncogenesis essentially result from proteomic disorders orchestrated by changes in DNA and/or cytoplasmic mRNA. These genetic fluctuations, however, cannot be decoded through conventional label-free methods (e.g., patch clamps, electrochemical cellular biosensors, etc.) or morphological characterization. Molecular beacons (MBs) have recently emerged as efficient probes for interrogating biomarkers in live cancer cells. MBs hybridize with their intracellular targets (e.g., mRNAs, DNAs, or proteins), emitting a fluorescent signal that can be quantified and correlated with the expression levels of their targets. In this review we discuss MB probes with different delivery platforms for intracellular probing as well as novel MB designs for detecting a variety of targets in living cancer cells. Finally, we describe current trends in MB-based intracellular biosensors.

Superior Impact Toughness and Excellent Storage Modulus of Poly(lactic acid) Foams Reinforced by Shish-Kebab Nanoporous Structure

Poly(lactic acid) (PLA) foams, with the combination of shish-kebab and spherulite nanoporous structure in skin and core layer respectively, was prepared using a novel technique comprising loop oscillating push-pull molding (LOPPM) and supercritical carbon dioxide low-temperature foaming process (SC-CO2LTFP). The foams present superior impact toughness which is 6-fold higher than that of neat PLA, and no significant decrease was observed for the storage modulus. Moreover, SC-CO2LTFP at soaking temperature ranging from 110 to 150 °C were performed to determine the evolution of pore morphology. The ultratough and supermoduli are unprecedented for PLA, and are in great need for broader applications.

Delivery of Nanoparticles for Treatment of Brain Tumor

BACKGROUND Malignant brain tumor is a highly challenging disease for diagnosis, treatment, and management. Cytotoxicity, distribution and the ability to cross blood brain barrier are some of the most significant issues for the chemotherapy of brain tumors. Nanotechnology has been widely exploited in drug delivery with great potential in improving the drug efficiency and efficacy. The advent of nanotechnology would greatly facilitate the early detection and treatment of brain tumors. This review will be primarily focused on current nano drug delivery system for brain cancer therapy. Meanwhile, the existing impediments for therapeutic nanomedicines and critical analysis of the different delivery nanoparticles are also discussed. METHODS We systematically evaluated the major factors that impact the current nanomedicines for brain tumor therapy. Meanwhile, various nanoparticle-based formulations for brain cancer detection and therapy are evaluated. RESULTS 124 papers were included in this review. From the analysis of the nanomaterials, seven major nanomaterials have been discussed regarding the functionality and current therapeutic significance. The review also explains in detail about the different types of nanomaterials and their functionalities. This shows that each of these nanomaterials has specialized functions for the treatment of various kinds of brain cancer. CONCLUSION Nanomaterials provide a viable potential diagnosis mechanis. In the future, more research needs to be focused on developing a better diagnosis tool for detection of cancer on an urgent basis. Blood-brain barrier and cytotoxicity are some of the primary root causes for the impediment of treatment of cancer using nanoparticles. Therefore, different delivery systems should be exploited for the nanoparticles to surmount these issues.

PEG/heparin-decorated lipid–polymer hybrid nanoparticles for long-circulating drug delivery

The clinical success of lipid–polymer hybrid nanoparticles (LPHNPs) for effective targeted drug delivery is still hindered by their rapid clearance from the bloodstream. In this work, a novel strategy for surface modification of LPHNPs with combined polyethylene glycol (PEG) and heparin (HEP) was developed to achieve a significant prolongation in blood circulation. All the LPHNPs formulated with a diameter of 100–200 nm were prepared by a modified w/o/w solvent diffusion/evaporation method and physicochemically characterized. The synergistic action of PEG and HEP was observed, as combinatorial modification significantly improved the surface hydrophilicity as well as the suspension stability of nanoparticles and tailored the surface charge close to neutrality, in comparison to LPHNPs surface-treated with PEG or HEP alone. In vitro and in vivo studies showed that the PEG/HEP coating significantly prohibited the macrophage uptake and extended the blood circulation of LPHNPs with concomitant reduced liver sequestration. The in vitro phagocytosis results using murine peritoneal macrophages showed 8.2-fold reduction compared to the control LPHNP group. The in vivo study in ICR mice showed PEG/HEP coating increased the blood circulation half-life of LPHNPs from 0.3 h to 72.6 h. Moreover, PEG/HEP LPHNPs exhibited dramatically reduced liver accumulation when compared to LPHNPs. These results demonstrated that PEG/HEP LPHNPs with optimized particle size, surface hydrophilicity and surface charge, have a promising potential as long-circulating drug delivery systems.

Enhanced strength and foamability of high-density polyethylene prepared by pressure-induced flow and low-temperature crosslinking

We report a high-performance high-density polyethylene (HDPE) with significantly enhanced mechanical strength by means of pressure-induced flow (PIF) and low-temperature crosslinking treatment. The tensile and flexural strengths increased from 23.5 and 36.2 MPa, up to 74.8 and 78.6 MPa, respectively. This was achieved by the elongated and flattened ‘brick-and-mud’ like crystal structure of HDPE occurred during PIF, and an adequate crosslinking network that was formed in the amorphous region beneath the melting point. Furthermore, high strength foams of this material could also be produced under supercritical CO2 batch foaming in solid-state.

Morphological Structure, Rheological Behavior, Mechanical Properties and Sound Insulation Performance of Thermoplastic Rubber Composites Reinforced by Different Inorganic Fillers

The application area of a sound insulation material is highly dependent on the technology adopted for its processing. In this study, thermoplastic rubber (TPR, polypropylene/ethylene propylene diene monomer) composites were simply prepared via an extrusion method. Two microscale particles, CaCO3 and hollow glass microspheres (HGW) were chosen to not only enhance the sound insulation but also reinforced the mechanical properties. Meanwhile, the processing capability of composites was confirmed. SEM images showed that the CaCO3 was uniformly dispersed in TPR matrix with ~3 μm scale aggregates, while the HGM was slightly aggregated to ~13 μm scale. The heterogeneous dispersion of micro-scale fillers strongly affected the sound transmission loss (STL) value of composites. The STL values of TPR composites with 40 wt % CaCO3 and 20 wt % HGM composites were about 12 dB and 7 dB higher than that of pure TPR sample, respectively. The improved sound insulation performances of the composites have been attributed to the enhanced reflection and dissipate sound energy in the heterogeneous composite. Moreover, the mechanical properties were also enhanced. The discontinued sound impedance and reinforced stiffness were considered as crucial for the sound insulation.

Synthetic Melanin E-Ink

Extensive efforts have been devoted to the development of surfactant-free electronic ink (E-ink) with excellent display resolution for high-definition resolution display. Herein, we report the use of polydopamine-based synthetic melanin, a class of functional nanoparticles with similar chemical compositions and physical properties to those of naturally occurring melanin, as a new E-ink material. It was found that such E-ink displays could achieve ultrahigh resolution (>10 000 ppi) and low power consumption (operation voltage of only 1 V) in aqueous solutions. Interestingly, simple oxidation of synthetic melanin nanoparticles enables the generation of intrinsic fluorescence, allowing further development of fluorescent E-ink displays with nanoscale resolution. We describe these bioinspired materials in an initial proof-of-concept study and propose that synthetic melanin nanoparticles will be suitable for electronic nanoinks with a potential wide range of applications in molecular patterning and fluorescence bioimaging.