Min Yin

Polyvalent Immunostimulatory Nanoagents with Self-Assembled CpG Oligonucleotide-Conjugated Gold Nanoparticles†

During the past decade, nucleic acid based therapeutics has developed from experimental techniques to preclinically practical strategies. Compared to conventional plasmid-containing transgenic methods, synthetic oligodeoxynucleotides (ODNs), including antisense DNA, aptamers, and small interfering RNAs (siRNAs), have emerged as highly attractive candidates for the treatment of various human diseases. [1] These ODNs are generally water soluble and stable with extremely low in vivo toxicity, and often interact with their targets with high specificity and sensitivity. Despite these advances, drug applications of ODNs are largely limited by delivery approaches. Naked ODNs cannot penetrate through the cell membrane and are prone to be cleared by nucleases in serum or cytoplasm. [1] The emergence of nanobiotechnology has provided unprecedented opportunities for biocompatible, low-toxicity, and highly efficient approaches for exogenous ODN administration in target cells. [2] Several promising nanomaterials, including gold nanoparticles (AuNPs), mesoporous silica nanoparticles, quantum dots, and carbon nanomaterials, have shown great promise as intracellular delivery nanoagents for imaging and gene regulation purposes. [3] In this work, we develop an AuNP-based polyvalent immunostimulatory nanoagent by using self-assembled cytosine–phosphate–guanosine (CpG) oligonucleotide-conjugated AuNPs (see Scheme 1). Unmethylated CpG motifs are widely present in the genomic DNA of invading bacteria and viruses, while most of the CpG sequences are methylated in the vertebrate

Enhanced Photoelectrochemical Water Splitting Performance of Anodic TiO2 Nanotube Arrays by Surface Passivation

One-dimensional anodic titanium oxide nanotube (TONT) arrays provide a direct pathway for charge transport, and thus hold great potential as working electrodes for electrochemical energy conversion and storage devices. However, the prominent surface recombination due to the large amount surface defects hinders the performance improvement. In this work, the surface states of TONTs were passivated by conformal coating of high-quality Al2O3 onto the tubular structures using atomic layer deposition (ALD). The modified TONT films were subsequently employed as anodes for photoelectrochemical (PEC) water splitting. The photocurrent (0.5 V vs Ag/AgCl) recorded under air mass 1.5 global illumination presented 0.8 times enhancement on the electrode with passivation coating. The reduction of surface recombination rate is responsible for the substantially improved performance, which is proposed to have originated from a decreased interface defect density in combination with a field-effect passivation induced by a negative fixed charge in the Al2O3 shells. These results not only provide a physical insight into the passivation effect, but also can be utilized as a guideline to design other energy conversion devices.

Dietary Iron Oxide Nanoparticles Delay Aging and Ameliorate Neurodegeneration in Drosophila.

Dietary iron oxide nanoparticles are shown to ameliorate neurodegeneration in a Drosophelia Alzheimers disease model. Iron oxide nanoparticles can mimic catalase and can decompose reactive oxygen species (ROS). This has potential therapeutic uses for aging, metabolic disorders, and neurodegenerative diseases, in which increased production of ROS is closely implicated.

Autophagy-Sensitized Cytotoxicity of Quantum Dots in PC12 Cells

Both CdTe and CdTe/CdS/ZnS quantum dots induce similar levels of autophagy in PC12 and HEK293 cells, while the former exhibits higher toxicity. Low levels of cadmium ions are not sufficient to induce either autophagy or cytotoxicity by themselves. Interestingly, the combination of cadmium ions and CdTe/CdS/ZnS mimics the toxic effect of CdTe, suggesting that autophagy sensitizes cells to cadmium ions.

High‐Performance and Omnidirectional Thin‐Film Amorphous Silicon Solar Cell Modules Achieved by 3D Geometry Design

High-performance thin-film hydrogenated amorphous silicon solar cells are achieved by combining macroscale 3D tubular substrates and nanoscaled 3D cone-like antireflective films. The tubular geometry delivers a series of advantages for large-scale deployment of photovoltaics, such as omnidirectional performance, easier encapsulation, decreased wind resistance, and easy integration with a second device inside the glass tube.

Enhanced photoelectrocatalytic performance of α-Fe2O3 thin films by surface plasmon resonance of Au nanoparticles coupled with surface passivation by atom layer deposition of Al2O3

The short lifetime of photogenerated charge carriers of hematite (α-Fe2O3) thin films strongly hindered the PEC performances. Herein, α-Fe2O3 thin films with surface nanowire were synthesized by electrodeposition and post annealing method for photoelectrocatalytic (PEC) water splitting. The thickness of the α-Fe2O3 films can be precisely controlled by adjusting the duration of the electrodeposition. The Au nanoparticles (NPs) and Al2O3 shell by atom layer deposition were further introduced to modify the photoelectrodes. Different constructions were made with different deposition orders of Au and Al2O3 on Fe2O3 films. The Fe2O3-Au-Al2O3 construction shows the best PEC performance with 1.78 times enhancement by localized surface plasmon resonance (LSPR) of NPs in conjunction with surface passivation of Al2O3 shells. Numerical simulation was carried out to investigate the promotion mechanisms. The high PEC performance for Fe2O3-Au-Al2O3 construction electrode could be attributed to the Al2O3 intensified LSPR, effective surface passivation by Al2O3 coating, and the efficient charge transfer due to the Fe2O3-Au Schottky junctions.

Silica Nanoparticles Target a Wnt Signal Transducer for Degradation and Impair Embryonic Development in Zebrafish.

Many types of biocompatible nanomaterials have proven of low cytotoxicity and hold great promise for various applications in nanomedicine. Whereas they generally do not cause apparent organ toxicity or tissue damage in adult animals, it is yet to determine their biological consequences in more general contexts. In this study, we investigate how silica nanoparticles (NPs) affect cellular activities and functions under several physiological or pathological conditions. Although silica NPs are generally regarded as “inert” nanocarriers and widely employed in biomedical studies, we find that they actively affect Wnt signaling in various types of cell lines, diminishing its anti-adipogenic effect in preadipocytes and pro-invasive effect in breast cancer cells, and more significantly, impair Wnt-regulated embryonic development in Zebrafish. We further demonstrate that intracellular silica NPs block Wnt signal transduction in a way resembling signaling molecules. Specifically, silica NPs target the Dvl protein, a key component of Wnt signaling cascade, for lysosomal degradation. As Wnt signaling play significant roles in embryonic development and adipogenesis, the observed physiological effects beyond toxicity imply potential risk of obesity, or developmental defects in somitogenesis and osteogenesis upon exposure to silica NPs. In addition, given the clinical implications of Wnt signaling in tumorigenesis and cancer metastasis, our work also establishes for the first time a molecular link between nanomaterials and the Wnt signaling pathway, which opens new door for novel applications of unmodified silica NPs in targeted therapy for cancers and other critical illness.

Nanodiamonds Mediate Oral Delivery of Proteins for Stem Cell Activation and Intestinal Remodeling in Drosophila.

Introduction of exogenous biomacromolecules into living systems is of great interest in genome editing, cancer immunotherapy, and stem cell reprogramming. Whereas current strategies generally depend on nucleic acids transfection, direct delivery of functional proteins that provides enhanced specificity, increased safety, and fast and temporal regulation is highly desirable. Nevertheless, intracellular delivery of intact and bioactive proteins, especially in vivo, remains poorly explored. In this study, we developed a nanodiamonds (NDs)-based protein delivery system in cultured cells and in Drosophila that showed high adsorption, high efficiency, and effective cytosolic release of fully functional proteins. Through live-cell imaging, we observed a novel phenomenon wherein a substantial amount of internalized NDs-protein complex rejected fusion with the early endosome, thereby evading protein degradation in the lysosome. More significantly, we demonstrated that dietary NDs-RNase induced apoptosis in enterocytes, stimulating regenerative divisions in intestinal stem cells and increasing the number of stem cells and precursor cells in Drosophila intestine. As stem cells are poorly accessible by exogenous agents in vivo, NDs-mediated oral delivery of proteins provides a new approach to modulate the stem cell microenvironment for intestinal remodeling, which has important implications for colorectal cancer therapy and regenerative medicine.

Deciphering active biocompatibility of iron oxide nanoparticles from their intrinsic antagonism

Magnetite nanoparticles (Fe3O4 NPs) are a well proven biocompatible nanomaterial, which hold great promise in various biomedical applications. Interestingly, unlike conventional biocompatible materials (e.g., polyethylene glycol (PEG)) that are chemically and biologically inert in nature, Fe3O4 NPs are known to be catalytically active and exhibit prominent physiological effects. Herein, we report an “active”, dynamic equilibrium mechanism for maintaining the cellular amenity of Fe3O4 NPs. We examined the effects of two types of iron oxide (magnetite and hematite) NPs in rat pheochromocytoma (PC12) cells and found that both induced stress responses. However, only Fe2O3 NPs caused significant programmed cell death; whereas Fe3O4 NPs are amenable to cells. We found that intrinsic catalase-like activity of Fe3O4 NPs antagonized the accumulation of toxic reactive oxygen species (ROS) induced by themselves, and thereby modulated the extent of cellular oxidative stress, autophagic activity, and programmed cell death. In line with this observation, we effectively reversed severe autophagy and cell death caused by Fe2O3 NPs via co-treatment with natural catalase. This study not only deciphers the distinct intrinsic antagonism of Fe3O4 NPs, but opens new routes to designing biocompatible theranostic nanoparticles with novel mechanisms.

Silicon Solar Cells: High-Performance and Omnidirectional Thin-Film Amorphous Silicon Solar Cell Modules Achieved by 3D Geometry Design (Adv. Mater. 42/2015).

High-performance thin-film hydrogenated amorphous silicon solar cells are achieved by combining macroscale 3D tubular substrates and nanoscale 3D cone-like antireflective films, as described on page 6747 by D. Li and co-workers. The tubular geometry delivers a series of advantages for the large-scale deployment of photovoltaics, such as omnidirectional performance, easier encapsulation, decreased wind resistance, and easy integration with a second device inside the glass tube.