Response time characteristics of a transmissive uniformly doped GaAsP photocathode.

In this paper, the matrix difference method is used to calculate the photoelectron continuity equation and the outgoing electron flux density equation. The effects of the GaAsP/AlGaAsP recombination rate, electron diffusion coefficient, and activation layer thickness on the time-resolved characteristics and quantum efficiency of a GaAsP photocathode are systematically studied, and the accuracy of the theoretical calculation is verified by experiments. The response speed and quantum efficiency of the GaAsP photocathode can be greatly improved by adjusting the thickness of the GaAsP activation layer reasonably.

Fabrication of Flexible Electrochromic Devices with Degradable and Fully Recyclable Features.

Electrochromic devices (ECDs) are in high demand for many applications; however, there is no ideal method to achieve the full recycling of the substrate and the functional layer in ECDs. Currently, it is still challenging to access ECDs with excellent electrochromic property, good degradability, and facile recycling capability. In this study, high-performance ECDs are successfully fabricated by using poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate) as the functional layer and transparent gelatin film (TGF) derived from pigskin as the substrate. Compared with PET films or PET-based ECDs, the optical transmittance of TGF and the coloration efficiency of our ECDs could be increased by 3.2 and 41.4%, respectively, showing a great potential to replace conventional plastic-based ECDs. Furthermore, the TGF not only showed good biodegradability but also could be regenerated via a simple process without the loss of desirable properties. In addition, the functional layer and substrate can be easily separated in water due to the adjusted interactions of the interface and the unique property of gelatin, which may open a new path for fabricating green electronics.

A novel microwave stimulus remote controlled anticancer drug release system based on Fe3O4@ZnO@mGd2O3:Eu@P(NIPAm-co-MAA) multifunctional nanocarriers.

The design of stimuli-responsive controlled drug delivery systems is a promising approach in cancer therapy, but it is still a major challenge to be capable of optimum therapeutic efficacy. Herein, we have elaborately fabricated Fe3O4@ZnO@mGd2O3:Eu (mGd2O3:Eu was short for mesoporous Gd2O3:Eu) multifunction composite nanoparticles by a simple process, with mesoporous Gd2O3:Eu shells as supports to increase the anticancer drug loading and thermally responsive polymer poly[(N-isopropylacrylamide)-co-(methacrylic acid)] (P(NIPAm-co-MAA)) gated mesoporous shells as microwave stimulus gatekeepers. The as-synthesized hybrid nanoparticles show a large accessible pore volume (0.19 cm3 g-1) and a high magnetization saturation value (27.8 emu g-1) for drug loading and targeting. The ZnO shells can effectively absorb and convert microwave to heat upon irradiation with microwaves, as a result of the microwave irradiation P(NIPAm-co-MAA) shrinks to a smaller volume and exposes the pores of the mesoporous luminescent shell, realizing the triggered release of the entrapped etoposide (VP16) drug (under microwave irradiation the VP16 release was about 81.7% within 10 h). In vitro studies show the multifunctional nanocarrier feasibility and advantage for remote-controlled drug release systems.

Multiple photosynthetic reaction centres using zinc porphyrinic oligopeptide-fulleropyrrolidine supramolecular complexes.

Multiple charge-separation sites have successfully been constructed using supramolecular complexes of multiporphyrinic oligopeptides [P(ZnP)(n), n = 2, 4, 8] with fulleropyrrolidine bearing a pyridine or imidazole coordinating ligand, which are organized by utilizing π-π interaction in addition to the coordination bond.

Early tissue response to citric acid-based micro- and nanocomposites.

Composites based on calcium phosphates and biodegradable polymers are desirable for orthopedic applications because of their potential to mimic bone. Herein, we describe the fabrication, characterization, and in vivo response of novel citric acid-based microcomposites and nanocomposites. Poly(1,8-octanediol-co-citrate) (POC) was mixed with increasing amounts of hydroxyapatite (HA) nanoparticles or microparticles (up to 60 wt %), and the morphology and mechanical properties of the resulting composites were assessed. To investigate tissue response, nanocomposites, microcomposites, POC, and poly(L-lactide) were implanted in osteochondral defects in rabbits and harvested at 6 weeks for histological evaluation. Scanning electron microscopy confirmed increased surface roughness of microcomposites relative to nanocomposites. The mechanical properties of both types of composites increased with increasing amounts of HA (8-328 MPa), although nanocomposites with 60 wt % HA displayed the highest strength and stiffness. Based on tissue-implant interfacial assessments, all implants integrated well with the surrounding bone and cartilage with no evidence of inflammation. Both nanocomposites and microcomposites supported bone remodeling; however, nanocomposites induced more trabecular bone formation at the tissue-implant interface. The mechanical properties of citric acid-based composites are within the range of human trabecular bone (1-1524 MPa, 211 ± 78 MPa mean modulus), and tissue response was dependent on the size and content of HA, providing new perspectives of design and fabrication criteria for orthopedic devices such as interference screws and fixation pins.

Sustained transgene expression via citric acid-based polyester elastomers.

Polymeric scaffolds are an important tool in tissue engineering and gene delivery using porous scaffolds can be a viable approach to control tissue response. Herein we describe the use of a biodegradable polyester elastomer, poly(1,8-octanediol-co-citrate) (POC), as a substrate for plasmid immobilization and cellular transfection of colonizing cells. Plasmid (pDNA), either complexed with poly(ethyleneimine) (PEI) forming polyplexes or in its native state, was surface-immobilized onto POC scaffolds via adsorption. Polyplex-containing scaffolds showed higher loading and slower initial rates of release than naked pDNA-containing scaffolds. Seeding of HEK293 cells and porcine aortic smooth muscle cells (PASMC) onto polyplex loaded-scaffolds demonstrated cell proliferation and transfection in vitro up to 12 days, significantly longer relative to bolus transfection. In vivo, transfection was evaluated using the mouse intraperitoneal (IP) fat model. In contrast to the in vitro study, successful long-term transgene delivery was only achieved with the naked pDNA-containing scaffolds. In particular, naked pDNA-containing scaffolds promoted high levels of both luciferase and green fluorescent protein (GFP) expression in vivo for 2 weeks. The results demonstrate that POC scaffolds are a suitable material for substrate-mediated gene delivery. POC scaffolds can potentially support long-term biological cues to mediate tissue formation through non-viral gene delivery.

A citric acid-based hydroxyapatite composite for orthopedic implants.

We describe a novel approach to process bioceramic microparticles and poly(diol citrates) into bioceramic-elastomer composites for potential use in orthopedic surgery. The composite consists of the biodegradable elastomer poly(1,8-octanediol-citrate) (POC) and the bioceramic hydroxyapatite (HA). The objective of this work was to characterize POC-HA composites and assess the feasibility of fabricating tissue fixation devices using machining and molding techniques. The mechanical properties of POC-HA composites with HA (40, 50, 60, 65wt.%) were within the range of values reported for tissue fixation devices (for POC-HA 65wt.%, S(b)=41.4+/-3.1, E(b)=501.7+/-40.3, S(c)=74.6+/-9.0, E(c)=448.8+/-27.0, S(t)=9.7+/-2.3, E(t)=334.8+/-73.5, S(s)=27.7+/-2.4, T(s)=27.3+/-4.9, all values in MPa). At 20 weeks, the weight loss of POC-HA composites ranged between 8 and 12wt.%, with 65wt.% HA composites degrading the slowest. Exposure of POC-HA to simulated body fluid resulted in extensive mineralization in the form of calcium phosphate with Ca/P of 1.5-1.7 similar to bone. POC-HA supported osteoblast adhesion in vitro and histology results from POC-HA samples that were implanted in rabbit knees for 6 weeks suggest that the composite is biocompatible. Synthesis of POC-HA is easy and inexpensive, does not involve harsh solvents or initiators, and the mechanical properties of POC-HA with 65wt.% HA are suitable for the fabrication of potentially osteoconductive bone screws.