Jiazhen Yan

Correlation of polymeric micelle sizes and their cellular internalization in vitro and tumor targeting in vivo

In order to explore the size effect of polymeric micelles on cellular internalization and tumor targeting, chrysin modified mPEG–PCL copolymer micelles with different particle sizes were fabricated to load Nile red as fluorescence probes. Four kinds of micelles with the mean sizes of 20, 40, 80 and 120 nm and narrow size distributions were prepared. The zeta potentials of the micelles were within −2 to 0 mV. The micelles were stable at low concentration (10−3 mg mL−1) for a long time of storage. The micelles were incubated with C2C12 myoblasts and 4T1 breast cancer cells to investigate their cellular uptake. It was found that the cellular internalization of the polymeric micelles was dependent on the cell line and particle size. The cellular uptake of the micelles in 4T1 cells was much better than that in C2C12 cells, and the polymeric micelles with a size of 120 nm exhibited the strongest red fluorescence. The Nile red loaded polymeric micelles were injected in mice via their tail vein to study tumor targeting in vivo. The micelles were mainly accumulated in the liver and kidney, however, different from the results in vitro, the red fluorescence intensity in the tumor administrated with polymeric micelles with a size of 40 nm was the strongest compared with the other three particles, which implied that micelles with a size of 40 nm exhibited efficient tumor targeting. This work provides guidelines for the rational design of polymeric micelles as carriers for efficient targeted drug delivery.

A facile one-pot dealloying strategy to synthesize monolithic asymmetry-patterned nanoporous copper ribbons with tunable microstructure and nanoporosity

In the present work, an effective and facile one-pot dealloying strategy has been developed to synthesize monolithic asymmetry-patterned nanoporous copper ribbons (AP-NPCRs) from melt-spun bi-phase Al 32 at% Cu alloy with trace α-Al. The microstructure and nanoporosity of these AP-NPCRs were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy, high-resolution transmission electron microscopy, and Brunauer–Emmett–Teller measurements. The results show that the cooling rate and dealloying solution have a significant influence on formation, microstructure and nanoporosity of AP-NPCRs. The quenching surface of porous products has regular bimodal channel size distributions regardless of corrosive solution species, while the free surface shows a homogeneous porous network nanostructure in acidic solution and anomalous bimodal nanoporous architecture in alkaline medium. Additionally, the microstructure (surface morphology, ligament/channel sizes and distribution) and nanoporosity of AP-NPCRs can be modulated effectively by simply changing the dealloying solution.

A facile one-pot oxidation-assisted dealloying protocol to massively synthesize monolithic core-shell architectured nanoporous copper@cuprous oxide nanonetworks for photodegradation of methyl orange

In this report, a facile and effective one-pot oxidation-assisted dealloying protocol has been developed to massively synthesize monolithic core-shell architectured nanoporous copper@cuprous oxide nanonetworks (C-S NPC@Cu2O NNs) by chemical dealloying of melt-spun Al 37 at.% Cu alloy in an oxygen-rich alkaline solution at room temperature, which possesses superior photocatalytic activity towards photodegradation of methyl orange (MO). The experimental results show that the as-prepared nanocomposite exhibits an open, bicontinuous interpenetrating ligament-pore structure with length scales of 20 ± 5 nm, in which the ligaments comprising Cu and Cu2O are typical of core-shell architecture with uniform shell thickness of ca. 3.5 nm. The photodegradation experiments of C-S NPC@Cu2O NNs show their superior photocatalytic activities for the MO degradation under visible light irradiation with degradation rate as high as 6.67 mg min−1 gcat−1, which is a diffusion-controlled kinetic process in essence in light of the good linear correlation between photodegradation ratio and square root of irradiation time. The excellent photocatalytic activity can be ascribed to the synergistic effects between unique core-shell architecture and 3D nanoporous network with high specific surface area and fast mass transfer channel, indicating that the C-S NPC@Cu2O NNs will be a promising candidate for photocatalysts of MO degradation.

Nanoporous copper from dual-phase alloy families and its technology application in lithium ion batteries

Abstract Nanoporous metals have recently attracted considerable interest in a wide variety of applications, including catalysis, sensors, actuators, fuel cells, microfluidic flow controllers, and so forth. Their inherent special morphology and characteristic is expected to have superior performances, such as the open porosity, high surface area, good electron conductivity, extremely clean metal surface, and high structural stability with no agglomeration in comparison with other nanostructures. Here, we mainly review our group’s systematical studies related to nanoporous copper (NPC) from dual-phase alloy families, aiming at giving a comprehensive summary about our step-by-step progress in its fabrication, microstructure evolution, dealloying behavior, and one-step strategies to special 3-D bicontinuous porous architectures in the last 5 years. Meanwhile, some encouraging test findings on the original application of NPC in lithium ion batteries have also been covered briefly in the last part of this review, which would open a window toward their other technology applications in high-performance electrochemical devices within the green, new energy industry.

Temperature-induced surface reconstruction and interface structure evolution on ligament of nanoporous copper

Micromorphology and atomic arrangement on ligament surface of nanoporous metals play a vital role in maintaining the structural stability, adjusting the reaction interface and endowing the functionality. Here we offer an instructive scientific understanding for temperature-induced surface reconstruction and interface structure evolution on ligament of nanoporous copper (NPC) based on systematically experimental observations and theoretical calculations. The results show that with dealloying temperature increasing, ligament surface micromorphology of NPC evolves from smooth to irregularity and to uniformly compressed semisphere, and finally to dispersed single-crystal nanoparticles accompanying with significant changes of interface structure from coherence to semi-coherence and to noncoherence. It can guide us to impart multifunctionality and enhanced reaction activity to porous materials just through surface self-modification of homogeneous atoms rather than external invasion of heteroatoms that may bring about unexpected ill effects, such as shortened operation life owing to poisoning.

Comparative analysis of the microstructures and mechanical properties of Co-Cr dental alloys fabricated by different methods

Statement of problem. Limited information is available regarding the microstructures and mechanical properties of Co‐Cr dental alloys prepared using conventional casting (CAST), computer numerical control (CNC) milling, and selective laser melting (SLM). Purpose. The purpose of this in vitro study was to evaluate the mechanical properties and microstructures of Co‐Cr dental alloys fabricated using conventional casting, computer numerical control milling, and selective laser melting and to estimate the potential of applying the SLM technique in prosthetic dentistry. Material and methods. Each group (n=6) of 50‐mm‐long Co‐Cr alloy, dumbbell‐shaped specimens was fabricated using the CAST, CNC, and SLM techniques. For each technique, the corresponding commercial alloy material was used. The mechanical properties were evaluated using a tensile test according to International Organization for Standardization (ISO) standard 6892, including 0.2% yield strength, ultimate tensile strength, elongation, and fracture analysis. The microstructures of the specimens were evaluated by using metallurgical microscopy, X‐ray diffraction (XRD), and scanning electron microscopy. The Tukey honest significant difference test (&agr;=.05) was used to statistically analyze the 0.2% yield strength, ultimate tensile strength, and microhardness values. Results. The microstructures of the SLM specimens exhibited homogeneously distributed fine grains, dispersed second‐phase particles, and few defects, and the XRD results showed the &agr;‐Co phase predominated, with minimal &egr;‐Co phase and no harmful needle &sgr; phase in the SLM group. The mean ±standard deviation of the 0.2% yield strength of the SLM specimens was 790 ±11 MPa, and the ultimate tensile strength was 1072 ±18 MPa. These values exceeded those of the CAST and CNC specimens by approximately 50% (P<.05). The SLM group showed the highest microhardness (475.3 ±10.2 HV10), followed by the CNC (325.2 ±17.8 HV10) and CAST group (323.7 ±27.2 HV10). Additionally, the ductility and toughness of the SLM specimens were also better than those of the other 2 groups. No significant differences were found in the mechanical performance between the CNC and CAST specimens (P>.05). Conclusions. The microstructures and mechanical properties of Co‐Cr dental alloys were dependent on the fabrication techniques. The SLM specimens exhibited better microstructures and mechanical properties than those fabricated with CNC or CAST.