Aggregation-Enhanced Photoluminescence and Photoacoustics of Atomically Precise Gold Nanoclusters in Lipid Nanodiscs (NANO2).

The authors designed a structurally stable nano-in-nano (NANO2) system highly capable of bioimaging via an aggregation-enhanced NIR excited emission and photoacoustic response achieved based on atomically precise gold nanoclusters protected by linear thiolated ligands [Au25(SC n H2n+1)18, n = 4-16] encapsulated in discoidal phospholipid bicelles through a one-pot synthesis. The detailed morphological characterization of NANO2 is conducted using cryogenic transmission electron microscopy, small/wide angle X-ray scattering with the support of molecular dynamics simulations, providing information on the location of Au nanoclusters in NANO2. The photoluminescence observed for NANO2 is 20-60 times more intense than that of the free Au nanoclusters, with both excitation and emission wavelengths in the near-infrared range, and the photoacoustic signal is more than tripled. The authors attribute this newly discovered aggregation-enhanced photoluminescence and photoacoustic signals to the restriction of intramolecular motion of the clusters' ligands. With the advantages of biocompatibility and high cellular uptake, NANO2 is potentially applicable for both in vitro and in vivo imaging, as the authors demonstrate with NIR excited emission from in vitro A549 human lung and the KB human cervical cancer cells.

Apparatus to Measure Subnanometer Fluctuation of Giant Unilamellar Vesicle Membranes.

The design, calibration, and performance of an apparatus are described to study the nanometer-scale thermal or driven fluctuations of free-standing vesicle membranes using a design resembling the position detection system of optical tweezers except for the laser power lower by orders of magnitude to avoid trapping. Over four decades of frequency, 1-10,000 Hz, it reports membrane fluctuation amplitudes 0.01-100 nm by measuring scattering of a laser beam as it passes membranes (∼1 µm cross-section) suspended in the aqueous medium. The low-power laser beam, <100 µW, is sharply focused on the edge of a giant unilamellar vesicle, and fluctuations of position are measured using a position-sensitive photodetector. The central result of this approach is the capability to reach small fluctuations otherwise inaccessible using other techniques. The typical obtained data are fit to the standard Helfrich mechanical model. The applications and limitations of the device are discussed, as well as other potential uses to which the apparatus may be applied by rational extension of the approach presented.

Biologically-active unilamellar vesicles from red blood cells.

We demonstrate a method to prepare giant unilamellar vesicles (GUVs) with biologically-active protein activity, by mixing erythrocyte (red blood cell) membrane extract with phospholipids and growing their mixture in a porous hydrogel matrix. This presents a pathway to retain protein biological activity without prior isolation and purification of the protein, though only the activity of the membrane protein GLUT1 is investigated to date. Using the cascade enzymatic reaction glucose oxidase and horseradish peroxidase to assay glucose concentration specifically within the GUV interior, we show that glucose is internalized by GLUT1 whereas adding cytochalasin B, a GLUT1 inhibitor, blocks glucose transport. The method presented here operates at biological ionic strength and is both simple and potentially generalizable.

The Diverse Range of Possible Cell Membrane Interactions with Substrates: Drug Delivery, Interfaces and Mobility.

The cell membrane has gained significant attention as a platform for the development of bio-inspired nanodevices due to its immune-evasive functionalities and copious bio-analogs. This review will examine several uses of cell membranes such as (i) therapeutic delivery carriers with or without substrates (i.e., nanoparticles and artificial polymers) that have enhanced efficiency regarding copious cargo loading and controlled release, (ii) exploiting nano-bio interfaces in membrane-coated particles from the macro- to the nanoscales, which would help resolve the biomedical issues involved in biological interfacing in the body, and (iii) its effects on the mobility of bio-moieties such as lipids and/or proteins in cell membranes, as discussed from a biophysical perspective. We anticipate that this review will influence both the development of novel anti-phagocytic delivery cargo and address biophysical problems in soft and complex cell membrane.

Effects of Membrane Defects and Polymer Hydrophobicity on Networking Kinetics of Vesicles.

The kinetics of clustering unilamellar vesicles induced by inverse Pluronics [poly(propylene oxide)m-poly(ethylene oxide)n-poly(propylene oxide)m, POm-EOn-POm] was investigated via experiments and molecular dynamic simulations. Two important factors for controlling the networking kinetics are the membrane defects, presumably located at the interfacial region between two lipid domains induced by acyl chain mismatch, and the polymer hydrophobicity. As expected, the clustering rate increases significantly with increasing bilayer defects on the membrane where the insertion of PPO is likely to take place because of the reduced energy barrier for the insertion of PO. The hydrophobic interaction between the PO blocks and membranes with the defects region dictates the "anchoring" kinetics, which is controlled by the association-dissociation of PO with the lipid membrane. As a result, the dependence of clustering rate on polymer concentration is strongly influenced by the hydrophobicity of the PO blocks. Nevertheless, longer PO blocks show stronger association with the membrane, resulting in faster consumption of the "active" sites made of these defect regions (causing mostly "invalid" insertions) with increasing polymer concentration, hence inhibiting the formation of large networking clusters, while shorter PO blocks undergo more frequent association with/dissociation from the defects, allowing continuous formation of larger clusters with increasing polymer concentration. This study provides important insights into how the organization and dynamics of a biomembrane influence its interaction with foreign amphiphilic molecules.

Simultaneous blockade of VEGF and Dll4 by HD105, a bispecific antibody, inhibits tumor progression and angiogenesis.

Several angiogenesis inhibitors targeting the vascular endothelial growth factor (VEGF) signaling pathway have been approved for cancer treatment. However, VEGF inhibitors alone were shown to promote tumor invasion and metastasis by increasing intratumoral hypoxia in some preclinical and clinical studies. Emerging reports suggest that Delta-like ligand 4 (Dll4) is a promising target of angiogenesis inhibition to augment the effects of VEGF inhibitors. To evaluate the effects of simultaneous blockade against VEGF and Dll4, we developed a bispecific antibody, HD105, targeting VEGF and Dll4. The HD105 bispecific antibody, which is composed of an anti-VEGF antibody (bevacizumab-similar) backbone C-terminally linked with a Dll4-targeting single-chain variable fragment, showed potent binding affinities against VEGF (KD: 1.3 nM) and Dll4 (KD: 30 nM). In addition, the HD105 bispecific antibody competitively inhibited the binding of ligands to their receptors, i.e., VEGF to VEGFR2 (EC50: 2.84 ± 0.41 nM) and Dll4 to Notch1 (EC50: 1.14 ± 0.06 nM). Using in vitro cell-based assays, we found that HD105 effectively blocked both the VEGF/VEGFR2 and Dll4/Notch1 signaling pathways in endothelial cells, resulting in a conspicuous inhibition of endothelial cell proliferation and sprouting. HD105 also suppressed Dll4-induced Notch1-dependent activation of the luciferase gene. In vivo xenograft studies demonstrated that HD105 more efficiently inhibited the tumor progression of human A549 lung and SCH gastric cancers than an anti-VEGF antibody or anti-Dll4 antibody alone. In conclusion, HD105 may be a novel therapeutic bispecific antibody for cancer treatment.

Nanoparticle puzzles and research opportunities that go beyond state of the art.

We present an overview of current progress and research challenges in the field of nanoparticle assembly, touching on the following topics: (1) historical perspective; (2) consideration of what is a nanoparticle; (3) contrast between nanoparticle self-assembly and top-down construction; (4) opportunities for nanoparticles with more intelligent sub-structures; (5) opportunities for nanoparticle systems cued to interact subtly in space and time. In this personal and subjective account, certain holy grails for nanoparticle science and technology are identified.

Unique effects of the chain lengths and anions of tetra-alkylammonium salts on quenching pyrene excimer.

Pyrene (Py) excimer, through its unique fluorescence quenching, exhibits high sensitivity and high selectivity in detecting specific electron-deficient molecules, providing a potential platform for sensing technology, optical switch, and probing hydrophobicity of molecular environment. In solution state, its quenching mechanism has been well-studied. However, there remain many unknown properties regarding the quenching mechanism of the solid-state Py excimer. In this paper, the effects of a series of tetra-alkylammonium salts (with a variety of chain lengths and anions) on Py excimer quenching are investigated to identify the controlling parameters of the fluorescence quenching in the binary system. Several experimental approaches including steady-state fluorescence spectroscopy, UV absorption, (13)C-nuclear magnetic resonance (NMR) spectra, X-ray diffraction, scanning electron microscopy, and time-dependent fluorescence decay are employed to seek for the fundamental understanding of the quenching mechanism. The result indicates a unique quenching effect of tetrabutylammonium cation on the pyrene excimer, and which is not observed in the other cations with different chain lengths (the same associated hexafluorophosphate anions). Meanwhile, hexafluorophosphate anion (in the presence of tetrabutylammonium) is able to effectively retain Py excimer fluorescence when the system is prepared by evaporating solvent at high temperature. It is also confirmed that dynamic quenching is involved in the process. Hydrophobic environment around Py molecules shows strong correlation with the formation of Py excimer. The knowledge obtained in this study provides the insights to how the interaction between salt and Py molecule affects the excimer fluorescence.

Association of tumor necrosis factor-α (TNF-α) promoter polymorphisms with overweight/obesity in a Korean population.

OBJECTIVE: Obesity is characterized by the activation of an inflammatory process leading to an increase in proinflammatory cytokines and adipokines. This study was designed to investigate the genetic association between tumor necrosis factor-α (TNF-α) polymorphisms and the risk of obesity in the Korean population. METHODS: Three single nucleotide polymorphisms [G-238A (rs361525), C-857T (rs1799724), and C-863A (rs1800630)] in the promoter region of TNF-α gene were analyzed in 123 control [body mass index (BMI) between 18 and 23] and 208 overweight/obese (BMI ≥ 23) subjects. RESULTS: The mean values of BMI in the control and overweight/obese groups were 21.1 ± 1.4 and 25.4 ± 1.8, respectively. Of the three SNPs, G-238A presented a significant association with overweight/obesity in the codominant model; the frequency of the G/G genotype in the overweight/obese group was 9.3% higher than that in the control group (P = 0.0046). When control and overweight/obesity subjects were combined together and analyzed, the level of high-density lipoprotein (HDL) was significantly higher in the C-857T C/C type SNP (P < 0.05). CONCLUSIONS: The results of this study suggest that the G allele of G-238A in TNF-α gene may be a risk factor for overweight/obesity in the Korean population and that the C allele of C-857T may be an protective factor in relation to the HDL level in the general Korean population.

Lower antioxidant vitamins (A, C and E) and trace minerals (Zn, Cu, Mn, Fe And Se) status in patients with cerebrovascular disease.

The management of antioxidant micronutrient status in patients with chronic diseases may be an important step in controlling disease progression and preventing deterioration in patient quality of life. The objective of this study was to investigate the antioxidant micronutrient status and lipid profiles of cerebrovascular disease (CbVD) patients and to compare this information with an evaluation of normal healthy subjects. A total of 57 male subjects (26 patients with CbVD and 31 healthy subjects) and 65 female subjects (32 patients with CbVD and 33 healthy subjects) were included in this cross-sectional study. Plasma lipid profiles, thiobarbituric acid-reactive substances (TBARS), fasting plasma concentration of antioxidant vitamins (A, C, E) and trace minerals (Cu, Zn, Mn, Fe and Se) were measured. Compared to healthy subjects, male but not female CbVD patients showed a lower energy intake (p < 0.01) which was largely due to a lower intake of dietary carbohydrate. They also consumed a diet containing a higher level of vitamins A and C. Plasma vitamin C (p < 0.01, in women) and vitamin E (p < 0.05, both in men and women) concentrations were prominently lower in the patients compared to healthy subjects. Plasma levels of the two antioxidant minerals Zn and Se were found to be markedly lower in the patients with CbVD, both in men and women (p < 0.05). Despite consuming less energy and food with a higher vitamin A and C level than healthy subjects, antioxidant micronutrient status, lipid peroxidation levels and the atherogenic index of male CbVD patients suggested that their antioxidant micronutrient intake was in some respects nutritionally inadequate. A similar conclusion could be made regarding the nutritional inadequacy of female CbVD patient diets. Expert dietary advice and intervention should be given to CbVD patients in order to optimize micronutrient intake and status.