Evolution of homopolymer thin-film instability on surface-anchored diblock copolymers varying in composition.

The stability of molecularly thin polymer films deposited on various material substrates is of critical importance to many contemporary nanotechnologies involving functional coatings and nano/micropatterned surfaces, in which case the causes responsible for film destabilization must be fully understood. Previous experimental studies report that factors such as film thickness and polymer molecular weight play significant roles in governing the rate, as well as mechanism, of destabilization. Complementary theoretical predictions reveal that surface heterogeneities can likewise induce (and regulate the process of) destabilization. In this study, we investigate the destabilization rate and mechanism of homopolystyrene (PS) films differing in thickness on top of poly(styrene-b-methyl methacrylate) (SM) diblock copolymer monolayers varying in chemical composition anchored to flat silica-like substrates to examine the effect of surface constitution on PS stability. Copolymers with a long M block consistently promote PS dewetting by nucleation and growth, wherein the linear dewetting rate decreases monotonically with increasing PS molecular weight, film thickness, and S fraction in the SM copolymer. In analogous studies involving a copolymer with a relatively short M block, however, PS dewetting proceeds instead by spinodal dewetting that evolves gradually into nucleation and growth as the film thickness is increased.

[Identification of a novel PAX6 mutation in a family with congenital aniridia].

OBJECTIVE: To detect potential mutation in a Chinese family where two individuals were affected with hereditary congenital aniridia. METHODS: Peripheral blood samples were taken for genomic DNA extraction. All of the 15 exons of PAX6 gene were amplified with PCR. The product were purified with gel electrophoresis and sequenced. RESULTS: In both patients, a novel deletion mutation (c.957-958delCA) in exon 13 of the PAX6 gene was identified, which has produced a terminator codon. The same mutation was not found in healthy controls. CONCLUSION: A c.957-958delCA mutation of PAX6 gene is probably the cause of aniridia in this Chinese family.

Clinical feature and predictive factor analysis for spontaneous regression of retinopathy of prematurity in a Chinese population.

AIM: To investigate the ratio of spontaneous regression of retinopathy of prematurity (ROP) and to explore the possible relevant predictive factors. METHODS: A retrospective review of 405 infants who were diagnosed with ROP and mother during pregnancy were collected. Stage, zone, and duration of ROP were recorded. Statistical analysis was performed on 51 possible predictive factors. RESULTS: Totally 356 infants showed spontaneous regression. The incidence was 100%, 95.3%, and 22.7% in stage 1, 2, and 3, respectively. The 13.4% of the ROP with plus disease eventually resolved spontaneously. All affected eyes of aggressive posterior retinopathy of prematurity (AP-ROP) failed to spontaneously regress. The mean duration of ROP was 7.2wk in patients with spontaneous resolution of ROP. Days of mechanical ventilation (OR=0.981, 95%CI, 0.965-0.997, P=0.021), retinal hemorrhage (OR=0.173, 95%CI, 0.064-0.470, P=0.001), delivery pattern (OR=2.750, 95%CI, 1.132-6.681, P=0.025), maternal anemia in pregnancy (OR=0.142, 95%CI, 0.036-0.563, P=0.005), the stages (at initial diagnosis OR=0.183, 95%CI, 0.041-0.816, P=0.026; at final diagnosis OR=0.031, 95%CI, 0.006-0.167, P<0.001), and with plus disease or not (OR=0.005, 95%CI, 0.001-0.031, P<0.001) were independent predictive factors of the spontaneous regression of ROP. CONCLUSION: Most mild ROP can spontaneously resolve. Active treatment is still recommended for stage 3 ROP, zone I ROP, AP-ROP, and ROP with plus disease. Prolonged mechanical ventilation and concurrent retinal hemorrhage reduce the likelihood of spontaneous ROP resolution. The pattern of delivery and the mother's anemia during pregnancy can also affect the prognosis of ROP.

Glutathione-triggered luminescent silver nanoparticle: A urinary clearable nanoparticle for potential clinical practice.

While inorganic nanoparticles (NPs) hold great promise for the revolution of current diagnostic techniques, potential risks of inorganic NPs on human health remain a big challenge and require to be thoroughly understood. In order to minimize the toxicity induced by the accumulation of NPs in reticuloendothelial system (RES), significant efforts have been devoted to the development of renal clearable nanomaterials by manipulating their surface-chemistry properties. In this work, a facile route is developed to fabricate luminescent silver nanoparticles (AgNPs), which reveal efficient renal clearance. Considering the fundamental importance and hopeful applications of the as-prepared AgNPs, we systematically investigate their biodistribution, pharmacokinetics, and renal clearance behaviors. Different from conventional metal NPs that are often severely accumulated in the vital organs, these luminescent renal clearable AgNPs demonstrate promisingly clinical translation for medical applications.

Film-Stabilizing Attributes of Polymeric Core-Shell Nanoparticles.

Self-organization of nanoparticles into stable, molecularly thin films provides an insightful paradigm for manipulating the manner in which materials interact at nanoscale dimensions to generate unique material assemblies at macroscopic length scales. While prior studies in this vein have focused largely on examining the performance of inorganic or organic/inorganic hybrid nanoparticles (NPs), the present work examines the stabilizing attributes of fully organic core-shell microgel (CSMG) NPs composed of a cross-linked poly(ethylene glycol dimethacrylate) (PEGDMA) core and a shell of densely grafted, but relatively short-chain, polystyrene (PS) arms. Although PS homopolymer thin films measuring from a few to many nanometers in thickness, depending on the molecular weight, typically dewet rapidly from silica supports at elevated temperatures, spin-coated CSMG NP films measuring as thin as 10 nm remain stable under identical conditions for at least 72 h. Through the use of self-assembled monolayers (SAMs) to alter the surface of a flat silica-based support, we demonstrate that such stabilization is not attributable to hydrogen bonding between the acrylic core and silica. We also document that thin NP films consisting of three or less layers (10 nm) and deposited onto SAMs can be fully dissolved even after extensive thermal treatment, whereas slightly thicker films (40 nm) on Si wafer become only partially soluble during solvent rinsing with and without sonication. Taken together, these observations indicate that the present CSMG NP films are stabilized primarily by multidirectional penetration of relatively short, unentangled NP arms caused by NP layering, rather than by chain entanglement as in linear homopolymer thin films. This nanoscale "velcro"-like mechanism permits such NP films, unlike their homopolymer counterparts of comparable chain length and thickness, to remain intact as stable, free-floating sheets on water, and thus provides a viable alternative to ultrathin organic coating strategies.

Crocetin induces cytotoxicity in colon cancer cells via p53-independent mechanisms.

OBJECTIVE: Crocin has been proposed as a promising candidate for cancer chemoprevention. The purpose of this investigation was to investigate the chemopreventive action and the possible mechanisms of crocin against human colon cancer cells in vitro. METHODS: Cell proliferation was examined using MTT assay and the cell cycle distribution fractions were analyzed using flow cytometric analysis after propidium iodide staining. Apoptosis was detected using the TUNEL Apoptosis Detection Kit with laser scanning confocal microscope. DNA damage was assessed using the alkaline single-cell gel electrophoresis assay, while expression levels of p53, cdk2, cyclin A and P21 were examined by Western blot analysis. RESULTS: Treatment of SW480 cells with crocetin (0.2, 0.4, 0.8 mmol/L) for 48 h significantly inhibited their proliferation in a concentration-dependent manner. Crocetin (0.8 mmol/L) significantly induced cell cycle arrest through p53-independent mechanisms accompanied by P21 induction. Crocetin (0.8 mmol/L) caused cytotoxicity in the SW480 cells by enhancing apoptosis and decreasing DNA repair capacity in a time-dependent manner. CONCLUSIONS: This report provides evidence that crocetin is a potential anticancer agent, which may be used as a chemotherapeutic drug.