Thickness-Controlled Phase Transitions of AB Diblock Copolymers in Asymmetric Ultrathin Films

An unusual hexagonal dot pattern has been observed in thin films of symmetric diblock copolymers experimentally. In order to verify the stability of the hexagonal dot pattern and understand its formation mechanism, we investigate the self-assembly of AB diblock copolymers in ultrathin films with a neutral top surface and a B-selective bottom surface using self-consistent field theory (SCFT) and dissipative particle dynamics (DPD). Our SCFT results reveal that ideally symmetric diblock copolymers with A-block volume fraction f = 0.5 can indeed form a hexagonal dot pattern in a certain range of film thickness (h), which is actually a half-period perforated lamellar (hPLA) morphology. The hPLA morphology transfers to a patternless half-period parallel lamella (hL∥) with increasing h and to a stripe pattern (L⊥) with decreasing h. The phase diagram with respect to f and h further demonstrates that the stable region of hPLA shifts to small f as h increases and disappears at a critical value of h. The formation of the hPLA region is mainly caused by the competition between the A/B interfacial energy and the overall surface energy (including top and bottom). In addition, the formation of hPLA is also verified by DPD simulations. Therefore, our work confirms that the experimentally observed dot pattern in thin films of symmetric diblock copolymers is an equilibrium morphology, the formation of which requires ultrathin thickness and asymmetric surface affinities

Integrated Strategy for High Luminescence Intensity of Upconversion Nanocrystals

The growing applications of upconversion nanocrystals in bioimaging, therapeutics, and photonics have given rise to a demand of high quality nanocrystals with desirable luminescence intensity. Although the design of optimal nanocrystals such as core–shell nanostructures has improved the intensity, the internal links between dopant concentration balance, epitaxial growth protection, and shell thickness effect encounter a compromised situation that lacks of integrated consideration and comprehensive assessment. Here we propose an integrated strategy based on a core–shell design for the enhancement of upconversion luminescence intensity. Epitaxial protection can enable higher activator accommodation capacity in limited spatial scale, which leads to an Er³⁺ concentration threshold improvement in β-NaYF₄ core–shell nanocrystals from 2 to 6 mol %. We further perform a comprehensive assessment of the nanocrystals with convincing performance improvement in ensemble spectroscopic intensity, upconversion quantum yield, and single nanocrystal intensity. Our findings provide improved understanding of electronic behaviors in multiphoton upconversion and opportunities for diverse applications requiring high quality upconversion nanocrystals

Capillary Imbibition of Polymer Mixtures in Nanopores

Capillary imbibition of homogeneous mixtures of entangled poly­(ethylene oxide) melts in nanopores of self-ordered nanoporous alumina follows a <i>t</i>^1/2 dependence but contradicts the classical Lucas–Washburn equation. Herein we employ reflection microscopy and self-consistent field theory (SCFT) calculations to demonstrate the <i>faster</i> penetration of nanopores for the <i>shorter</i> chains. Combined results suggest on average an ∼15% enrichment by the shorter chains. On top of that, SCFT shows an enrichment of the short chains near the pore surface. Possible applications in separating long and short polymer chains by the difference in imbibition speedin the absence of solventare discussed

Capillary Imbibition of Polymer Mixtures in Nanopores

Capillary imbibition of homogeneous mixtures of entangled poly­(ethylene oxide) melts in nanopores of self-ordered nanoporous alumina follows a <i>t</i>^1/2 dependence but contradicts the classical Lucas–Washburn equation. Herein we employ reflection microscopy and self-consistent field theory (SCFT) calculations to demonstrate the <i>faster</i> penetration of nanopores for the <i>shorter</i> chains. Combined results suggest on average an ∼15% enrichment by the shorter chains. On top of that, SCFT shows an enrichment of the short chains near the pore surface. Possible applications in separating long and short polymer chains by the difference in imbibition speedin the absence of solventare discussed

Pumping Small Molecules Selectively through an Energy-Assisted Assembling Process at Nonequilibrium States

In living organisms, precise control over the spatial and temporal distribution of molecules, including pheromones, is crucial. This level of control is equally important for the development of artificial active materials. In this study, we successfully controlled the distribution of small molecules in the system at nonequilibrium states by actively transporting them, even against the apparent concentration gradient, with high selectivity. As a demonstration, in the aqueous solution of acid orange (AO7) and TMC10COOH, we found that AO7 molecules can coassemble with transient anhydride (TMC10CO)2O to form larger assemblies in the presence of chemical fuel 1-ethyl-3-(3-(dimethylamino)propyl) carbodiimide hydrochloride (EDC). This led to a decrease in local free AO7 concentration and caused AO7 molecules from other locations in the solution to move toward the assemblies. Consequently, AO7 accumulates at the location where EDC was injected. By continuously injecting EDC, we could maintain a stable high value of the apparent AO7 concentration at the injection point. We also observed that this process which operated at nonequilibrium states exhibited high selectivity

Ultrasensitive Polarized Up-Conversion of Tm³⁺–Yb³⁺ Doped β‑NaYF₄ Single Nanorod

Up-conversion luminescence in rare earth ions (REs) doped nanoparticles has attracted considerable research attention for the promising applications in solid-state lasers, three-dimensional displays, solar cells, biological imaging, and so forth. However, there have been no reports on REs doped nanoparticles to investigate their polarized energy transfer up-conversion, especially for single particle. Herein, the polarized energy transfer up-conversion from REs doped fluoride nanorods is demonstrated in a single particle spectroscopy mode for the first time. Unique luminescent phenomena, for example<i>,</i> sharp energy level split and singlet-to-triplet transitions at room temperature, multiple discrete luminescence intensity periodic variation with polarization direction, are observed upon excitation with 980 nm linearly polarized laser. Furthermore, nanorods with the controllable aspect ratio and symmetry are fabricated for analysis of the mechanism of polarization anisotropy. The comparative experiments suggest that intraions transition properties and crystal local symmetry dominate the polarization anisotropy, which is also confirmed by density functional theory calculations. Taking advantage of the REs based up-conversion, potential application in polarized microscopic multi-information transportation is suggested for the polarization anisotropy from REs doped fluoride single nanorod or nanorod array

Entropy-Induced Localization and Sliding Dynamics of Rings on Polyrotaxane

Regulating the position and sliding dynamics of rings on the polyrotaxane (PR) backbone plays a crucial role in determining the properties and/or functions of PR and PR-based soft materials. In this work, we use molecular dynamics simulations to reveal that the features of localization and sliding dynamics of rings on a PR modeled by a rod–coil–rod triblock copolymer are regulated by the entropy effect of the coil block. The distribution of the rings along the rod–coil–rod PR backbone is found to be highly heterogeneous and can be described by a two-state model characterized by a (free) energy gap, ΔE, which depends on the three characteristic parameters of the PR system, ΔE = ΔE(α, μ, ρring), where α is the ratio of the rod to the coil strand length, μ is a quantity of measuring the stretching degree of the coil block, and ρring is the overall ring coverage along the PR backbone. A theoretical model is proposed to describe the origin of this universality, the prediction of which is quantitatively consistent with simulation results for the single-ring rod–coil–rod PR system. The existence of an energy gap also gives a model for the dynamics of ring sliding along the PR backbone

Lanthanide Complex for Single-Molecule Fluorescent in Situ Hybridization and Background-Free Imaging

Traditional single-molecule fluorescence in situ hybridization (smFISH) methods for RNA detection often face sensitivity challenges due to the low fluorescence intensity of the probe. Also, short-lived autofluorescence complicates obtaining clear signals from tissue sections. In response, we have developed an smFISH probe using highly grafted lanthanide complexes to address both concentration quenching and autofluorescence background. Our approach involves an oligo PCR incorporating azide-dUTP, enabling conjugation with lanthanide complexes. This method has proven to be stable, convenient, and cost-effective. Notably, for the mRNA detection in SKBR3 cells, the lanthanide probe group exhibited 2.5 times higher luminescence intensity and detected 3 times more signal points in cells compared with the Cy3 group. Furthermore, we successfully applied the probe to image HER2 mRNA molecules in breast cancer FFPE tissue sections, achieving a 2.7-fold improvement in sensitivity compared to Cy3-based probes. These results emphasize the potential of time-resolved smFISH as a highly sensitive method for nucleic acid detection, free of background fluorescence interference

Metabolic Phenotypes in Pancreatic Cancer

<div><p>Introduction</p><p>The aim of present study was to profile the glucose-dependent and glutamine- dependent metabolism in pancreatic cancer.</p><p>Methods</p><p>We performed Immunohistochemical staining of GLUT1, CAIX, BNIP3, p62, LC3, GLUD1, and GOT1. Based on the expression of metabolism-related proteins, the metabolic phenotypes of tumors were classified into two categories, including glucose- and glutamine-dependent metabolism. There were Warburg type, reverse Warburg type, mixed type, and null type in glucose-dependent metabolism, and canonical type, non-canonical type, mixed type, null type in glutamine-dependent metabolism.</p><p>Results</p><p>Longer overall survival was associated with high expression of BNIP3 in tumor (p = 0.010). Shorter overall survival was associated with high expression of GLUT1 in tumor (P = 0.002) and GOT1 in tumor (p = 0.030). Warburg type of glucose-dependent metabolism had a highest percentage of tumors with nerve infiltration (P = 0.0003), UICC stage (P = 0.0004), and activated autophagic status in tumor (P = 0.0167). Mixed type of glucose-dependent metabolism comprised the highest percentage of tumors with positive marginal status (P<0.0001), lymphatic invasion (P<0.0001), and activated autophagic status in stroma (P = 0.0002). Mixed type and Warburg type had a significant association with shorter overall survival (P = 0.018). Non-canonical type and mixed type of glutamine-dependent metabolism comprised the highest percentage of tumors with vascular invasion (p = 0.0073), highest percentage of activated autophagy in tumors (P = 0.0034). Moreover, these two types of glutamine-dependent metabolism were significantly associated with shorter overall survival (P<0.001). Further analysis suggested that most of tumors were dependent on both glucose- and glutamine-dependent metabolism. After dividing the tumors according to the number of metabolism, we found that the increasing numbers of metabolism subtypes inversely associated with survival outcome.</p><p>Conclusion</p><p>Warburg type, non-canonical type and mixed types of glucose- and glutamine-dependent metabolism comprised of more metabolically active, biologically aggressive and poor prognostic tumors. Moreover, the increasing subtypes and categories of the metabolism in each tumor significantly associated with poor prognosis.</p></div

Efficient Dual-Modal NIR-to-NIR Emission of Rare Earth Ions Co-doped Nanocrystals for Biological Fluorescence Imaging

A novel approach has been developed for the realization of efficient near-infrared to near-infrared (NIR-to-NIR) upconversion and down-shifting emission in nanophosphors. The efficient dual-modal NIR-to-NIR emission is realized in a β-NaGdF₄/Nd³⁺@NaGdF₄/Tm³⁺–Yb³⁺ core–shell nanocrystal by careful control of the identity and concentration of the doped rare earth (RE) ion species and by manipulation of the spatial distributions of these RE ions. The photoluminescence results reveal that the emission efficiency increases at least 2-fold when comparing the materials synthesized in this study with those synthesized through traditional approaches. Hence, these core–shell structured nanocrystals with novel excitation and emission behaviors enable us to obtain tissue fluorescence imaging by detecting the upconverted and down-shifted photoluminescence from Tm³⁺ and Nd³⁺ ions, respectively. The reported approach thus provides a new route for the realization of high-yield emission from RE ion doped nanocrystals, which could prove to be useful for the design of optical materials containing other optically active centers