HBsAg, the surface antigen of the hepatitis B virus (HBV), is used as a model to study the mechanisms and dynamics of a single-enveloped virus infecting living cells by imaging and tracking at the single-particle level. By monitoring the fluorescent indicator of HBsAg particles, it is found that HBsAg enters cells via a caveolin-mediated endocytic pathway. Tracking of individual HBsAg particles in living cells reveals the anomalously actin-dependent but not microtubule-dependent motility of the internalized HBsAg particle. The motility of HBsAg particles in living cells is also analyzed quantitatively. These results may settle the long-lasting debate of whether HBV directly breaks the plasma membrane barrier or relies on endocytosis to deliver its genome into the cell, and how the virus moves in the cell.
Water-soluble nano-C(60) can serve as a novel, effective, fluorescent sensing platform for biomolecular detection with high sensitivity and selectivity. In this paper, fluorescent detection of DNA and thrombin via nano-C(60) is demonstrated for the first time. The principle of the assay lies in the fact that the adsorption of the fluorescently labeled single-stranded DNA (ssDNA) probe by nano-C(60) leads to substantial fluorescence quenching. In the presence of a target, the biomolecular mutual interaction suppresses this quenching, signaling the existence of the target. This sensing system rivals graphene oxide but is superior to other carbon-structure-based systems. The present method can also achieve multiplex DNA detection and withstand the interference from human blood serum.
The high-molar-extinction-coefficient heteroleptic ruthenium aye, cis-Ru (4,4'-bis(5-octylthieno3,2-b] thiophen-2-yl)-2,2'-bipyridine) (4,4'-dicarboxyl-2,2'-bipyridine) (NCS)(2), exhibits an AM 1.5 solar (100 mW cm(-2))-to-electric power-conversion efficiency of 4.6% in a solid-state dye-sensitized solar cell (SSDSC) with 2,2', 7,7'-tetrakis-(N,N-di-p-methoxyphenylamine,)9,9'-spirobifluorene (spiro-MeOTAD) as the organic hole-transporting material. These SSDSC devices exhibit good durability during accelerated tests under visible-light soaking for 1000 h at 60 degrees C. This demonstration elucidates a class of photovoltaic devices with potential for stable and low-cost power generation. The electron recombination dynamics and charge collection that take place at the dye-sensitized heterojunction are studied by means of impedance and transient photovoltage decay techniques.
Nanocarriers are a new type of nonviral gene carriers, many of which have demonstrated a broad range of pharmacological and biological properties, such as being biodegradable in the body, stimulus-responsive towards the surrounding environment, and an abiltiy to specifically targeting certain disease sites. By summarizing some main types of nanocarriers, this Concept considers the current status and possible future directions of the potential clinical applications of multifunctional nanocarriers, with primary attention on the combination of such properties as biodegradability, targetability, transfection ability, and stimuli sensitivity.
A class of core-shell nanoparticles possessing a layer of biocompatible shell and hydrophobic core with embedded oxygen-sensitive platinum-porphyrin (PtTFPP) dyes is developed via a radical-initiated microemulsion co-polymerization strategy. The influences of host matrices and the PtTFPP incorporation manner on the photophysical properties and the oxygen-sensing performance of the nanoparticles are investigated. Self-loading capability with cells and intracellular-oxygen-sensing ability of the as-prepared nanoparticle probes in the range 0%-20% oxygen concentration are confirmed. Polymeric nanoparticles with optimized formats are characterized by their relatively small diameter (<50 nm), core-shell structures with biocompatible shells, covalent-attachment-imparted leak-free construction, improved lifetime dynamic range (up to 44 s), excellent storage stability and photostability, and facile cell uptake. The nanoparticles' small sensor diameter and core-shell structure with biocompatible shell make them suitable for intracellular detection applications. For intracellular detection applications, the leak-free feature of the as-prepared nanoparticle sensor effectively minimizes potential chemical interferences and cytotoxicity. As a salient feature, improved lifetime dynamic range of the sensor is expected to enable precise oxygen detection and control in specific practical applications in stem-cell biology and medical research. Such a feature-packed nanoparticle oxygen sensor may find applications in precise oxygen-level mapping of living cells and tissue.
A novel light-operated vehicle for targeted intracellular drug delivery is constructed using photosensitizer-incorporated G-quadruplex DNA-capped mesoporous silica nanoparticles. Upon light irradiation, the photosensitizer generates ROS, causing the DNA capping to be cleaved and allowing cargo to be released. Importantly, this platform makes it possible to develop a drug-carrier system for the synergistic combination of chemotherapy and PDT for cancer treatment with spatial/temporal control. Furthermore, the introducing of targeting ligands further improves tumor targeting efficiency. The excellent biocompatibility, cell-specific intracellular drug delivery, and cellular uptake properties set up the basis for future biomedical application that require in vivo controlled, targeted drug delivery.
Amyloid fibril formation is a critical step in Alzheimer's disease (AD) pathogenesis. Inhibition of A aggregation has shown promising against AD and has been used in clinic trials. Here, a novel strategy is reported for the self-assembly of polyoxometalate-peptide (POM@P) hybrid particles as bifunctional A inhibitors. The two-in-one bifunctional POM@P nanoparticles show an enhanced inhibition effect on amyloid aggregation in mice cerebrospinal fluid. Incorporating a clinically used A fibril-staining dye, congo red (CR), into the hybrid colloidal spheres, the nanoparticles can also act as an effective fluorescent probe to monitor the inhibition process of POM@P via CR fluorescence change in real time. It is believed that such flexible organic-inorganic hybrid systems may prompt the design of new multifunctional materials for AD treatment.