Unraveling the structure-chirality sensing relationship between achiral anthracene-based tetracationic nanotubes and nucleosides in aqueous host-guest complexation.

In biological systems, nucleosides play crucial roles in various physiological processes. In this study, we designed and synthesized four achiral anthracene-based tetracationic nanotubes (1-4) as artificial hosts and chiroptical sensors for nucleosides in aqueous media. Notably, different nanotubes exhibit varied chirality sensing on circular dichroism (CD)/circularly polarized luminescence (CPL) spectra through the host-guest complexation, which prompted us to explore the factors influencing their chiroptical responses. Through systematic host-guest experiments, the structure-chirality sensing relationship between achiral anthracene-based tetracationic nanotubes and nucleosides in the host-guest complexation was unraveled. Firstly, the CD response originates from the anthracene rings situated at the side-wall position, resulting from the right-handed (P)- or left-handed (M)-twisted conformation of the macrocyclic structure. Secondly, the CPL signal is influenced by the presence of anthracene rings at the linking-wall position, which results from intermolecular chiral twisted stacking between these anthracene rings. Therefore, these nanotubes can serve as chiroptical sensor arrays to enhance the accuracy of nucleotide recognition through principal component analysis (PCA) analysis based on the diversified CD spectra. This study provides insights for the construction of adaptive chirality from achiral nanotubes with dynamic conformational nature and might facilitate further design of chiral functional materials for several applications.

Biomimetic Hydrogen-Bonded G ⋠C ⋠G ⋠C Quadruplex within a Tetraphenylethene-Based Octacationic Spirobicycle in Water.

In biological systems, nucleotide quadruplexes (such as G-quadruplexes) in DNA and RNA that are held together by multiple hydrogen bonds play a crucial functional role. The biomimetic formation of these hydrogen-bonded quadruplexes captured by artificial systems in water poses a significant challenge but can offer valuable insights into these complex functional structures. Herein, we report the formation of biomimetic hydrogen-bonded G ⋅ C ⋅ G ⋅ C quadruplex captured by a tetraphenylethene (TPE) based octacationic spirobicycle (1). The spirobicyclic compound possesses a three-dimensional (3D) crossing dual-cavity structure, which enables the encapsulation of four d(GpC) dinucleotide molecules, thereby realizing 1 : 4 host-guest complexation in water. The X-ray structure reveals that four d(GpC) molecules further form a two-layer G ⋅ C ⋅ G ⋅ C quadruplex with Watson-Crick hydrogen bonds, which are stabilized within the dual hydrophobic cavities of 1 through the cooperative non-covalent interactions of hydrogen bonds, CH⋅⋅⋅π interactions, and hydrophobic effect. Due to the dynamically-rotational propeller chirality of TPE units, 1 with adaptive chirality can further serve as a chiroptical sensor to exhibit opposite Cotton effects with mirror-image CD spectra for the pH-dependent hydrogen-bonded assemblies of d(GpC) including the Watson-Crick G ⋅ C ⋅ G ⋅ C (pH 9.22) and Hoogsteen G ⋅ C+ ⋅ G ⋅ C+ (pH 5.74) quartets through the host-guest chirality transfer in water.

Precise Recognition in Water by an Endo-Functionalized Cavity: Tuning the Complementarity of Binding Sites.

Precise binding towards structurally similar substrates is a common feature of biomolecular recognition. However, achieving such selectivity-especially in distinguishing subtle differences in substrates-with synthetic hosts can be quite challenging. Herein, we report a novel design strategy involving the combination of different rigid skeletons to adjust the distance between recognition sites within the cavity, which allows for the highly selective recognition of hydrogen-bonding complementary substrates, such as 4-chromanone. X-ray single-crystal structures and density functional theory calculations confirmed that the distance of endo-functionalized groups within the rigid cavity is crucial for achieving high binding selectivity through hydrogen bonding. The thermodynamic data and molecular dynamics simulations revealed a significant influence of the hydrophobic cavity on the binding affinity. The new receptor possesses both high selectivity and high affinity, which provide valuable insights for the design of customized receptors.

Chiral recognition of neutral guests by chiral naphthotubes with a bis-thiourea endo-functionalized cavity.

Developing chiral receptors with an endo-functionalized cavity for chiral recognition is of great significance in the field of molecular recognition. This study presents two pairs of chiral naphthotubes containing a bis-thiourea endo-functionalized cavity. Each chiral naphthotube has two homochiral centers which were fixed adjacent to the thiourea groups, causing the skeleton and thiourea groups to twist enantiomerically through chiral transfer. These chiral naphthotubes are highly effective at enantiomerically recognizing various neutral chiral molecules with an enantioselectivity up to 17.0. Furthermore, the mechanism of the chiral recognition has been revealed to be originated from differences in multiple non-covalent interactions. Various factors, such as the shape of cavities, substituents of guests, flexibility of host and binding modes are demonstrated to contribute to creating differences in the non-covalent interactions. Additionally, the driving force behind enantioselectivity is mainly attributed to enthalpic differences, and enthalpy -entropy compensation has also been observed to influence enantioselectivity.

Synthesis and aqueous anion recognition of an imidazolium-based nonacationic cup.

An imidazolium-based nonacationic cup (1·9X; X = PF6- or Cl-) was synthesized via step-by-step SN2 reactions without using any template. The water-soluble 1·9Cl- as a molecular container can encapsulate anionic nucleoside triphosphate and dinucleotide molecules (e.g., ATP and NADH) inside its cavity through hydrogen bonds and electrostatic interactions in aqueous solution.

Hierarchical Two-Level Supramolecular Chirality of an Achiral Anthracene-Based Tetracationic Nanotube in Water.

Herein, we report an achiral anthracene-based tetracationic nanotube (1⋅4Cl- ) that shows two levels of supramolecular chirality: namely, conformationally adaptive host-guest complexation with nucleoside triphosphates (e.g. ATP, GTP, CTP, and UTP) and twisted packing of the chiral host-guest complexes in water. Interestingly, achiral 1⋅4Cl- exhibits chiral recognition for ATP/GTP and CTP/UTP through structural transformation of its intramolecular M- and P-twisted conformation as the first level of supramolecular chirality, which leads to adaptive chirality with opposite CD responses. Furthermore, the formation of chiral M-1⋅4Cl- ⊃ATP can promote an intermolecular P-twisted dimeric packing of anthracene rings as the second level of supramolecular chirality to achieve assembled chirality with strong circularly polarized luminescence arising from the excimer ((+)-CPL, glum ≈10-2 ) in water.

Adaptive chirality of achiral tetraphenylethene-based tetracationic cyclophanes with dual responses of fluorescence and circular dichroism in water.

Two tetraphenylethene-based tetracationic cyclophanes 1 and 2 were synthesized via a one-step SN2 reaction without using any template. Based on the fluorescence and rotational conformation of the tetraphenylethene units, these water-soluble cyclophanes exhibited adaptive chirality with dual responses of turn-on fluorescence and induced circular dichroism when combined with nucleotides and DNA in water.

Tetraphenylethene-Based Platinum(II) Bis-Triangular Dicycles with Tunable Emissions.

Tunable luminescent materials have attracted considerable interest for their wide applications in electronic optical devices, biological probes and sensors, tunable displays, and security technologies. Herein, we describe a strategy of coordination-driven self-assembly in order to prepare discrete tetraphenylethene-based platinum(II) bis-triangular dicycles 1 and 2 with aggregation-induced emission properties. The X-ray structure confirms that they possess two triangular cavities in which free rotation of the central TPE unit is restricted. As a kind of fluorescent material, the AIE-active dicycles have good emissions with wide tunability based on their aggregate states by changing different solvents, adjusting the temperature, or combining them with other dyes (e.g., perylene) via a co-assembly process.

Tetraphenylethene-based tetracationic dicyclophanes: synthesis, mechanochromic luminescence, and photochemical reactions.

Two tetraphenylethene-based tetracationic dicyclophanes 1 and 2 were synthesized via a one-step SN2 reaction. Based on the central TPE unit and the slight difference of the outer linkers, 1 and 2 exhibited a classic aggregation-induced emission but contrasting mechanochromic luminescence under grinding, vaporing, or hydrostatic pressure in the solid state, and photochemical reactions with various emitting colours induced by photoirradiation in the solution state.

Aggregation-Induced Emission and Light-Harvesting Function of Tetraphenylethene-Based Tetracationic Dicyclophane.

Here we report one-pot synthesis of tetraphenylethene-based tetracationic dicyclophane (1) and its self-assembly behaviors with aggregation-induced emission (AIE) and light-harvesting function. Confirmed by X-ray crystal structure and high resolution transmission electron microscopy, this tetracationic dicyclophane can self-assemble into a 3D supramolecular framework to form crystalline nanospheres (2) finally, which exhibits a strong emission (ΦF = 97.7%) via AIE effect in aqueous solution. Interestingly, AIE-active 2 as a single-molecule-based fluorescent supramolecular platform can encapsulate an organic dye (e.g., Nile red) to form light-harvesting nanospheres (3) further with a large red-shift (Δλ = ∼70 nm), highly efficient energy-transfer ability (ΦET = 77.5%), and high antenna effect (14.3).

Cucurbit[10]uril-Based [2]Rotaxane: Preparation and Supramolecular Assembly-Induced Fluorescence Enhancement.

As the cucurbit[n]uril (CB[n]) homologue with the largest cavity size, cucurbit[10]uril (CB[10]) can encapsulate big guests to form interesting host-guest complexes/assemblies. Herein, we report the preparation and fluorescence properties of CB[10]-based [2]rotaxane (CB[10]·1) formed from cucurbit[10]uril and dumbbell-like guest 1. This [2]rotaxane (CB[10]·1) is assembled by C═O···N+ ion-dipole interactions between oxygen atoms of the carbonyl fringed portals of CB[10] and the positively charged pyridinium units of 1 via the slipping method under heating at 95 °C in DMSO. In contrast, other cucurbit[n]uril (CB[n], n = 6-8) homologues cannot form rotaxanes with 1 due to their smaller cavities. The dumbbell-like guest 1 is a poor emitter in DMSO. Interestingly, the formation of CB[10]·1 renders the restriction of intramolecular rotation of TPE, which features a strong fluorescent intensity, long lifetime, and high quantum yield. Furthermore, CB[10]·1 is shown to aggregate plate-like structures with various sizes in different solvents (DMSO, THF, or CHCl3), resulting in a stepwise aggregation-induced emission enhancement effect. This kind of CB[10]-based [2]rotaxane may be used to fabricate luminescent systems with unique emission properties.

Biological security evaluation of cross-linked hyaluronic acid for ophthalmic implant material / 中华实验眼科杂志

Background Hyaluronic acid is a mucopolysaccharide existing in extracellular matrix and having good biocompatibility.Using chemical crosslinking method can improve the physical properties of the material,so cross-linked hyaluronic has potential clinical application value.Objective The present study was to evaluate the histocompatibility and biological security of cross-linked hyaluronic acid as ophthalmic implant material.Methods Cross-linked hyaluronic acid implant material was prepared according to the criteria of Biological Evaluation of Medical Devices (GB/T16886.5-2003).Eighteen 8-week-old male New Zealand white rabbits were randomized into the experimental group and the control group.Cross-linked hyaluronic acid material with 5.0 mm diameter was implanted into corneal stroma interlaminationally in the experimental group,and only corneal stromal interlaminational pocket was made without any implanting material in the control group.Biological response of cornea was assessed in vivo from 1 week through 3 months after operation by slit lamp microscope.The corneas were obtained 2 weeks,1 month and 3 months respectively for histopathological examination.Mouse embryonic fibroblasts were cultured in cross-linked hyaluronic acid film plate,medical silicone material culture plate and regular culture plate respectively for 24 hours,and the cell growth state and morphology were observed under the inverted microscope and scan electron microscope.MTT assay was used to test the relative growth rate of the cultured cells 48 hours after cultured using extracted liquid of hyaluronic acid implant material.Results Cross-linked hyaluronic acid implant material showed a well healing to the corneas of rabbits during the observation duration,without obvious inflammatory response and neovascularization.The arrangement of stromal fibers was uniform in order,and no infiltration of inflammatory cells was seen under the light microscope.The cells grew well after cultured with cross-linked hyaluronic acid film and regular medium for 24 hours,but in the silicone culture group,fewer of adherent cells and more floating cells were found.The relative growth rate of the cells was 87.50％ 48 hours after cultured with extracted liquid of hyaluronic acid implant material.Conclusions The cross-linked hyaluronic acid material has good histocompatibility and biological security in rabbit cornea tissue.

Inhibitory Effect of Curcumin on Proliferation of Human Pterygium Fibroblasts / 华中科技大学学报（医学）（英德文版）

In order to investigate the effect of curcumin on proliferation and apoptosis of human pterygium fibroblasts (HPF) in culture and search for a new method to prevent the recurrence after pterygium surgery, HPF was incubated with 0-160 μmol/L curcumin for 24-96 h. The MTT method was used to assay the biologic activities of curcumin at different time points and different doses. The expression of proliferating cell nuclear antigen (PCNA) in each group was detected by immunohistochemistry. The cell cycle distribution was detected by flow cytometry (FCM). Administration of 20-80 μmol/L curcumin for 24-72 h could significantly inhibit HPF proliferation in a dose- and time-dependent manner (P＜0.05). After treatment with curcumin at different concentrations of 20, 40, 80 and 160 μmol/L for 24 h, FCM revealed there was a significant sub-G1 peak at each concentration. The number of HPF in G0/G1 phase was increased, while in S phase, it was decreased (P＜0.05). At the concentration of 20-80 μmol/L, curcumin, in a dose-dependent manner (P＜0.05), could inhibit the expression of PCNA in HPF. It was suggesterd that curcumin could significantly inhibit the proliferation of HPF, make HPF arrest in G0/G1 phase and induce the apoptosis of HPF in a dose- and time-dependent manner.

Inhibitory effect of curcumin on proliferation of human pterygium fibroblasts / 华中科技大学学报（医学）（英德文版）

In order to investigate the effect of curcumin on proliferation and apoptosis of human pterygium fibroblasts (HPF) in culture and search for a new method to prevent the recurrence after pterygium surgery, HPF was incubated with 0-160 micromol/L curcumin for 24-96 h. The MTT method was used to assay the biologic activities of curcumin at different time points and different doses. The expression of proliferating cell nuclear antigen (PCNA) in each group was detected by immunohistochemistry. The cell cycle distribution was detected by flow cytometry (FCM). Administration of 20-80 micromol/L curcumin for 24-72 h could significantly inhibit HPF proliferation in a dose-and time-dependent manner (P<0.05). After treatment with curcumin at different concentrations of 20, 40, 80 and 160 micromol/L for 24 h, FCM revealed there was a significant sub-G1 peak at each concentration. The number of HPF in G0/G1 phase was increased, while in S phase, it was decreased (P<0.05). At the concentration of 20-80 micromol/L, curcumin, in a dose-dependent manner (P<0.05), could inhibit the expression of PCNA in HPF. It was suggested that curcumin could significantly inhibit the proliferation of HPF, make HPF arrest in G0/G1 phase and induce the apoptosis of HPF in a dose-and time-dependent manner.

Reconstructed corneal endothelial tissue on allo-stroma in vitro / 中国病理生理杂志

AIM: In order to search carrier material and better tissue culture method, the morphology and structure of the cultured cat corneal endothelium was observed. METHODS: The cat corneal endothelial cells were seeded on the Descemet's membrane of the dehydrated swine corneal stroma, and then cultured in the medium with epidermal growth factor and laminin for 7 days. The morphology and structure of reconstructed tissue was tested by the inverted microscope and the scanning electron microscope. RESULTS: As shown by the morphological observations, the cultured cat corneal endothelial cells formed an integrated membrane, and attached to the Descemet's membrane, which was similar to the nature tissue. The cells connected tightly to each other, and some of them arranged in hexagon approximately. CONCLUSION: The cat corneal endothelial cells could be rebuilt on the carrier of the dehydrated swine corneal stroma successfully, which is similar to the nature tissue.

Study on animal intracorneal implantation model with xenogeneic swine corneal stroma / 中国病理生理杂志

0.05). (2) In the total 12 rabbits, all the cornea grafts survived without rejection reaction, corneal haze or corneal neovascularization. The fresh grafts got transparent after 2 months, and the dehydrated grafts got transparent after 6 months. Histological study demonstrated both fresh and dehydrated stroma grafts had fused with rabbits'corneal stroma very well without lymphocytes infiltrating. (3) As shown in histological observations, the reconstructed cat corneal endothelial tissue was similar to the nature tissue. Cultured cat endothelial cells connected tightly to each other and attached to the Descemet's membrane closely. CONCLUSION: Swine corneal stroma has low immunogenicity and satisfying biocompatibility,it is an ideal biological carrier for cornea reconstruction in vitro.