Self-assembly of like-charged nanoparticles into microscopic crystals

Like-charged nanoparticles, NPs, can assemble in water into large, faceted crystals, each made of several million particles. These NPs are functionalized with mixed monolayers comprising ligands terminating in carboxylic acid group ligands as well as positively charged quaternary ammonium ligands. The latter groups give rise to electrostatic interparticle repulsions which partly offset the hydrogen bonding between the carboxylic acids. It is the balance between these two interactions that ultimately enables self-assembly. Depending on the pH, the particles can crystallize, form aggregates, remain unaggregated or even-in mixtures of two particle types-can choose whether to crystallize with like-charged or oppositely charged particles.open

Self-assembly of like-charged nanoparticles into microscopic crystals

Like-charged nanoparticles, NPs, can assemble in water into large, faceted crystals, each made of several million particles. These NPs are functionalized with mixed monolayers comprising ligands terminating in carboxylic acid group ligands as well as positively charged quaternary ammonium ligands. The latter groups give rise to electrostatic interparticle repulsions which partly offset the hydrogen bonding between the carboxylic acids. It is the balance between these two interactions that ultimately enables self-assembly. Depending on the pH, the particles can crystallize, form aggregates, remain unaggregated or even-in mixtures of two particle types-can choose whether to crystallize with like-charged or oppositely charged particles.open

WNT5A gene and protein expression in endometrial cancer

Introduction. WNT5A (Wnt family member 5A) belongs to the WNT family of secreted signaling glycoproteins that play essential role in developmental, physiological and pathological processes. WNT5A was shown to take part in carcinogenesis process playing both oncogenic and suppressor functions in various types of human malignancies. This study aimed to assess the expression of the WNT5A gene at the mRNA and protein levels in the specimens derived from endometrial cancer (EC) or unchanged control endometrium. The associations between the WNT5A expression levels and clinicopathological characteristics and survival of EC patients were evaluated. Materials and methods. Total RNA was isolated in order to assess the relative amounts of WNT5A mRNA by quantitative polymerase chain reaction (QPCR) in samples of unchanged endometrial control (n = 8) and tumor samples of EC patients (n = 28). Immunohistochemistry (IHC) was used to determine the presence of WNT5A protein in the sections of formalin-fixed, paraffin-embedded tissue specimens derived from unchanged endome­trial controls (n = 6) and EC tumors (n = 19). Significance of differences in WNT5A expression levels between the studied groups of EC patients and correlations between the WNT5A and demographic data, pathological features, hematological parameters and overall survival of the patients were evaluated by statistical analysis. Results. The level of WNT5A mRNA was decreased in EC in comparison to unchanged endometrium. WNT5A expression was associated with primary tumor invasion status exhibiting reduced level of transcripts in EC that involved organs beyond the uterus when compared to the uterus-confined cancers. WNT5A immunoreactivity was visualized in the cytoplasm and nuclei of EC cells as well as in the luminal and glandular epithelial cells of unchanged endometrium. WNT5A mRNA expression levels correlated negatively with cytoplasmic, and positively with nuclear immunoreactivity of the WNT5A protein in the EC cells. In addition, the relationships between blood leucocyte count (in particular granulocytes and lymphocytes) of patients with EC and their WNT5A mRNA and protein expression levels were established. A positive correlation between the nuclear immunoexpression of WNT5A protein in the cancer cells in cell nuclei and mean platelet volume in blood was also found. Conclusions. The results of the first study of WNT5A expression at the transcript and protein levels indicate that it could be considered as a potential marker of molecular changes that take place during EC development

Underexpression of LATS1 TSG in colorectal cancer is associated with promoter hypermethylation

AIM: To investigate large tumor suppressor 1 (LATS1) expression, promoter hypermethylation, and microsatellite instability in colorectal cancer (CRC). METHODS: RNA was isolated from tumor tissue of 142 CRC patients and 40 colon mucosal biopsies of healthy controls. After reverse transcription, quantitative polymerase chain reaction (PCR) was performed, and LATS1 expression was normalized to expression of the ACTB and RPL32 housekeeping genes. To analyze hypermethylation, genomic DNA was isolated from 44 tumor CRC biopsies, and methylation-specific PCR was performed. Microsatellite instability (MSI) status was checked with PCR using BAT26, BAT25, and BAT40 markers in the genomic DNA of 84 CRC patients, followed by denaturing gel electrophoresis. RESULTS: Decreased LATS1 expression was found in 127/142 (89.4%) CRC cases with the average ratio of the LATS1 level 10.33 ± 32.64 in CRC patients vs 32.85 ± 33.56 in healthy controls. The lowest expression was found in Dukes’ B stage tumors and G1 (well-differentiated) cells. Hypermethylation of the LATS1 promoter was present in 25/44 (57%) CRC cases analyzed. LATS1 promoter hypermethylation was strongly associated with decreased gene expression; methylated cases showed 162× lower expression of LATS1 than unmethylated cases. Although high-grade MSI (mutation in all three markers) was found in 14/84 (17%) cases and low-grade MSI (mutation in 1-2 markers) was found in 30/84 (36%) cases, we found no association with LATS1 expression. CONCLUSION: Decreased expression of LATS1 in CRC was associated with promoter hypermethylation, but not MSI status. Such reduced expression may promote progression of CRC

Assessment of corneal dynamics with high-speed swept source Optical Coherence Tomography combined with an air puff system

We present a novel method and instrument for in vivo imaging and measurement of the human corneal dynamics during an air puff. The instrument is based on high-speed swept source optical coherence tomography (ssOCT) combined with a custom adapted air puff chamber from a non-contact tonometer, which uses an air stream to deform the cornea in a non-invasive manner. During the short period of time that the deformation takes place, the ssOCT acquires multiple A-scans in time (M-scan) at the center of the air puff, allowing observation of the dynamics of the anterior and posterior corneal surfaces as well as the anterior lens surface. The dynamics of the measurement are driven by the biomechanical properties of the human eye as well as its intraocular pressure. Thus, the analysis of the M-scan may provide useful information about the biomechanical behavior of the anterior segment during the applanation caused by the air puff. An initial set of controlled clinical experiments are shown to comprehend the performance of the instrument and its potential applicability to further understand the eye biomechanics and intraocular pressure measurements. Limitations and possibilities of the new apparatus are discussed

Swept source OCT with air puff chamber for corneal dynamics measurements

None of currently used tonometers produce estimated IOP values that are free of errors. Measurement incredibility arises from indirect measurement of corneal deformation and the fact that pressure calculations are based on population averaged parameters of anterior segment. Reliable IOP values are crucial for understanding and monitoring of number of eye pathologies e.g. glaucoma. We have combined high speed swept source OCT with air-puff chamber. System provides direct measurement of deformation of cornea and anterior surface of the lens. This paper describes in details the performance of air-puff ssOCT instrument. We present different approaches of data presentation and analysis. Changes in deformation amplitude appears to be good indicator of IOP changes. However, it seems that in order to provide accurate intraocular pressure values an additional information on corneal biomechanics is necessary. We believe that such information could be extracted from data provided by air-puff ssOCT

Nanoseparations: Strategies for size and/or shape-selective purification of nanoparticles

This paper reviews techniques currently available for size- and shape-selective purification of nanoscopic objects. The methods discussed range from variants of familiar chromatographic, centrifugation, or filtration techniques, to purification schemes deriving from nanoscale-specific phenomena, including shape-selective reactivity, or propensity to form organized superstructures

Vesicle-to-Micelle Oscillations and Spatial Patterns

A pH oscillator is coupled to and controls rhythmic interconversion of nanoscopic vesicles and micelles made of fatty acids. When changes in pH are combined with diffusion, self-assembly produces spatially extended patterns of vesicle/micelle "stripes" or concentric "shells"

Controlled pH Stability and Adjustable Cellular Uptake of Mixed-Charge Nanoparticles

Nanoparticles functionalized with mixed self-assembled monolayers (m-SAMs) comprising positively and negatively charged thiols are stable at both low and high pH but precipitate sharply at the pH where the charges on the particle are balanced (pH(prec)). By adjusting the proportion of the positively and negatively, charged ligands in the m-SAM or changing particle size, pH(prec) can be varied flexibly between similar to 4 and similar to 7. In addition, changes in the SAMs' composition and particles' net charge translate into different degrees of cellular uptake. Remarkably, the presence of the positively, charged thiols allows for the uptake of particles having net negative charge

Rapid Deposition of Hydrophobic Nanoparticle Monolayers onto Hydrophilic Surfaces from Liquid-Liquid Interfaces

Dense, hydrophobic coatings comprising hydrophilic nanoparticles are deposited rapidly from water/toluene emulsions. The process of deposition is driven by a Subtle interplay between interfacial phenomena, electrostatic interparticle repulsions. and hydrogen bonding between the NPs and the substrate(s). The packing fractions and the plasmonic properties of the coatings can be controlled by the pH of the aqueous phase. Once formed, the coatings can be further functionalized without a loss of mechanical integrity