An Orthogonal Dynamic Covalent Polymer Network with Distinctive Topology Transformations for Shape- and Molecular Architecture Reconfiguration.

Bond exchange in a typical dynamic covalent polymer network allows access to macroscopic shape reconfigurability, but the network architecture is not altered. An alternative possibility is that the network architecture can be designed to switch to various topological states corresponding to different material properties. Achieving both in one network can expand the material scope, but their intrinsically conflicting mechanisms make it challenging. We design a dynamic covalent network that can undergo two orthogonal topological transformations, namely transesterification on the branched chains and olefin metathesis on the mainframe. This allows independent control of the macroscopic shape and molecular architecture. With this design, we illustrate a bottlebrush network with programmable shape and spatially definable mechanical properties. Our strategy paves a way to on-demand regulation of network polymers.

Life-threatening event in laparoscopic hepatic surgery: Training curriculum on sudden hepatic artery haemorrhage.

BACKGROUND: Exposure of the hepatic artery is a fundamental step in many surgeries, during which iatrogenic hepatic artery injury may occur. Although the incidence of hepatic artery haemorrhage is low, its occurrence can lead to life-threatening haemorrhage. It is difficult and dangerous to accumulate clinical experience in laparoscopic hepatic artery repair in actual patients, and simulation training models for laparoscopic hepatic artery repair are currently lacking. In this study, a 3D printed model was designed to simulate the training curriculum for sudden hepatic artery haemorrhage, but whether training with the 3D printed model could yield superior skill improvement for surgeons remained to be determined. METHODS: A new 3D printed model was designed for this study. Surgeons from the General Surgery Department of Sir Run Run Shaw Hospital participated in this simulation training. The surgical performance of each model was compared, and the authenticity of the model was evaluated and mechanically tested. RESULTS: Experienced surgeons performed better on the 3D printed model. After repeated training, inexperienced surgeons showed significant improvement of their laparoscopic hepatic artery repair skills. The authenticity of the model was generally satisfactory, but shortcomings persisted in the mechanical testing of artery wall tearing, necessitating further improvement. CONCLUSIONS: Few studies have investigated laparoscopic simulation training for sudden hepatic artery haemorrhage. This simulation model distinguishes surgeons with different levels of experience and allows those with less experience to improve their laparoscopic hepatic artery repair skills through training on the model.

Association between type 2 diabetes, alcohol intake frequency, age at menarche, and gallbladder cancer: a two-sample Mendelian randomization study.

Background: Gallbladder cancer (GBC) is a rare malignancy of the digestive tract, characterized by a remarkably poor prognosis. Currently, there is a controversy on the relationship between type 2 diabetes (T2D) and GBC. Additionally, no definitive conclusions were established regarding the causal relationships between alcohol intake frequency (AIF), age at menarche (AAM) and GBC. The objective of this study was to elucidate the causal association between T2D, AIF, AAM, and GBC. Methods: Single-nucleotide polymorphisms (SNPs) associated with exposures and outcomes were sourced from the Integrative Epidemiology Unit (IEU) Open Genome-Wide Association Study (GWAS) database. Specifically, the data of GBC comprised 907 East Asians (pathological results of all cases were registered into Biobank Japan) and 425,707 SNPs; T2D comprised 655,666 Europeans with 5,030,727 SNPs; AIF comprised 462,346 Europeans and 9,851,867 SNPs; AAM comprised 243,944 Europeans and 9,851,867 SNPs. The measurement of exposure traits is collected uniformly from the UK Biobank (UKB) database and presented in the form of standard deviation (SD) or the logarithmic form of the odds ratio (logOR). We employed a two-sample Mendelian randomization (MR) analysis to discern the causalities between T2D, AIF, AAM, and GBC. Sensitivity analyses were conducted to identify and address potential heterogeneity, horizontal pleiotropy, and outliers. Results: Our findings indicated that T2D reduced GBC risk [odds ratio (OR) =0.044; 95% confidence interval (CI): 0.004-0.55; P=0.015, inverse variance-weighted (IVW)]. However, no causal relationship was observed between AIF (OR =0.158; 95% CI: 5.33E-05 to 466.84; P=0.65, IVW), AAM (OR =0.19; 95% CI: 0.0003-140.34; P=0.62, IVW), and GBC. Sensitivity analysis revealed no evidence of horizontal pleiotropy, heterogeneity, or outliers, suggesting the robustness and reliability of our conclusions. Conclusions: T2D emerged as a potentially protective factor against GBC, whereas neither AIF nor AAM demonstrated a causal relationship with GBC risk. Regulation of glucose metabolism may be one of the methods for preventing GBC.

Intrinsic Permanent Shape Reconfigurable Semicrystalline Biopolyester Thermoset.

Catalyst-free, volatile organic solvent (VOC)-free synthesis of biobased cross-linked polymers is an important sustainable feature in polyesterification. To date, these polyesters have been extensively studied for their fundamental sustainability across various uses. The ultimate potential sustainability for these materials, however, is constrained to static structural parts due to their intractable rigid three-dimensional (3D) network. Here, we reveal intrinsic dynamic exchangeable bonds within this type of cross-linked semicrystalline network, poly(1,8-octanediol-co-1,12-docanedioate-co-citrate) (PODDC), enabling permanent shape reconfigurability. Annealing at slightly above melting-transition temperature (Tm) allows for shape reconfigurability up to nine times, comparable in performance to the existing bond-exchange systems. No reagents are involved from synthesis to shape reconfiguration, suggesting an exciting feature exhibited by this sustainable cross-linked material without the need for further chemical modification. We further extend this benefit of reconfigurability to enable flexible shape design in a smart shape-memory polymer (SMP), showing it as one of its potential applications. After its applications, it can undergo hydrolytic degradation. We envision that such multifaceted sustainability for the material will attract interest in environmentally friendly applications such as fabricating external part of soft robots and shape-morphing devices with reduced environmental impact.

Inhibition of Heterogeneous Nucleation in Water by Hydrogel Coating.

Heterogeneous nucleation plays a critical role in the phase transition of water, which can cause damage in various systems. Here, we report that heterogeneous nucleation can be inhibited by utilizing hydrogel coatings to isolate solid surfaces and water. Hydrogels, which contain over 90% water when fully swelled, exhibit a high degree of similarity to water. Due to this similarity, there is a great energy barrier for heterogeneous nucleation along the water-hydrogel interface. Additionally, hydrogel coatings, which possess polymer networks, exhibit higher fracture energy and more robust adhesion to solid surfaces compared to water. This high fracture and adhesion energy acts as a deterrent for fracture nucleation within the hydrogel or along the hydrogel-solid interface. With a hydrogel layer approximately 100 µm thick, the boiling temperature of water under atmospheric pressure can be raised from 100 to 108 °C. Notably, hydrogel coatings also result in remarkable reductions in cavitation pressure on multiple solid surfaces. We have demonstrated the efficacy of hydrogel coatings in preventing damages resulting from acceleration-induced cavitation. Hydrogel coatings have the potential to alter the energy landscape of heterogeneous nucleation on the water-solid interface, making them an exciting avenue for innovation in heat transfer and fluidic systems.

Sustainable Approach for the Synthesis of a Semicrystalline Polymer with a Reversible Shape-Memory Effect.

Shape-memory polymers (SMPs) have demonstrated potential for use in automotive, biomedical, and aerospace industries. However, ensuring the sustainability of these materials remains a challenge. Herein, a sustainable approach to synthesize a semicrystalline polymer using biomass-derivable precursors via catalyst-free polyesterification is presented. The synthesized biodegradable polymer, poly(1,8-octanediol-co-1,12-dodecanedioate-co-citrate) (PODDC), exhibits excellent shape-memory properties, as evidenced by good shape fixity and shape recovery ratios of 98%, along with a large reversible actuation strain of 28%. Without the use of a catalyst, the mild polymerization enables the reconfiguration of the partially cured two-dimensional (2D) film to a three-dimensional (3D) geometric form in the middle process. This study appears to be a step forward in developing sustainable SMPs and a simple way for constructing a 3D structure of a permanent shape.

Adhesive cryogel particles for bridging confined and irregular tissue defects.

BACKGROUND: Reconstruction of damaged tissues requires both surface hemostasis and tissue bridging. Tissues with damage resulting from physical trauma or surgical treatments may have arbitrary surface topographies, making tissue bridging challenging. METHODS: This study proposes a tissue adhesive in the form of adhesive cryogel particles (ACPs) made from chitosan, acrylic acid, 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The adhesion performance was examined by the 180-degree peel test to a collection of tissues including porcine heart, intestine, liver, muscle, and stomach. Cytotoxicity of ACPs was evaluated by cell proliferation of human normal liver cells (LO2) and human intestinal epithelial cells (Caco-2). The degree of inflammation and biodegradability were examined in dorsal subcutaneous rat models. The ability of ACPs to bridge irregular tissue defects was assessed using porcine heart, liver, and kidney as the ex vivo models. Furthermore, a model of repairing liver rupture in rats and an intestinal anastomosis in rabbits were established to verify the effectiveness, biocompatibility, and applicability in clinical surgery. RESULTS: ACPs are applicable to confined and irregular tissue defects, such as deep herringbone grooves in the parenchyma organs and annular sections in the cavernous organs. ACPs formed tough adhesion between tissues [(670.9 ± 50.1) J/m2 for the heart, (607.6 ± 30.0) J/m2 for the intestine, (473.7 ± 37.0) J/m2 for the liver, (186.1 ± 13.3) J/m2 for muscle, and (579.3 ± 32.3) J/m2 for the stomach]. ACPs showed considerable cytocompatibility in vitro study, with a high level of cell viability for 3 d [(98.8 ± 1.2) % for LO2 and (98.3 ± 1.6) % for Caco-2]. It has comparable inflammation repair in a ruptured rat liver (P = 0.58 compared with suture closure), the same with intestinal anastomosis in rabbits (P = 0.40 compared with suture anastomosis). Additionally, ACPs-based intestinal anastomosis (less than 30 s) was remarkably faster than the conventional suturing process (more than 10 min). When ACPs degrade after surgery, the tissues heal across the adhesion interface. CONCLUSIONS: ACPs are promising as the adhesive for clinical operations and battlefield rescue, with the capability to bridge irregular tissue defects rapidly.

Bioinspired soft robots for deep-sea exploration.

The deep ocean, Earth's untouched expanse, presents immense challenges for exploration due to its extreme pressure, temperature, and darkness. Unlike traditional marine robots that require specialized metallic vessels for protection, deep-sea species thrive without such cumbersome pressure-resistant designs. Their pressure-adaptive forms, unique propulsion methods, and advanced senses have inspired innovation in designing lightweight, compact soft machines. This perspective addresses challenges, recent strides, and design strategies for bioinspired deep-sea soft robots. Drawing from abyssal life, it explores the actuation, sensing, power, and pressure resilience of multifunctional deep-sea soft robots, offering game-changing solutions for profound exploration and operation in harsh conditions.

The Dynamic Mortise-and-Tenon Interlock Assists Hydrated Soft Robots Toward Off-Road Locomotion.

Natural locomotion such as walking, crawling, and swimming relies on spatially controlled deformation of soft tissues, which could allow efficient interaction with the external environment. As one of the ideal candidates for biomimetic materials, hydrogels can exhibit versatile bionic morphings. However, it remains an enormous challenge to transfer these in situ deformations to locomotion, particularly above complex terrains. Herein, inspired by the crawling mode of inchworms, an isotropic hydrogel with thermoresponsiveness could evolve to an anisotropic hydrogel actuator via interfacial diffusion polymerization, further evolving to multisection structure and exhibiting adaptive deformation with diverse degrees of freedom. Therefore, a dynamic mortise-and-tenon interlock could be generated through the interaction between the self-deformation of the hydrogel actuator and rough terrains, inducing continual multidimensional locomotion on various artificial rough substrates and natural sandy terrain. Interestingly, benefiting from the powerful mechanical energy transfer capability, the crawlable hydrogel actuators could also be utilized as hydrogel motors to activate static cargos to overstep complex terrains, which exhibit the potential application of a biomimetic mechanical discoloration device. Therefore, we believe that this design principle and control strategy may be of potential interest to the field of deformable materials, soft robots, and biomimetic devices.

Versatile and Simple Strategy for Preparing Bilayer Hydrogels with Janus Characteristics.

Bilayer hydrogels are attracting tremendous attention for their capability to integrate several different functions on the two sides of the gel, that is, imparting the gel with Janus characteristics, which is highly desired in many engineering and biomedical applications including soft actuators, hydrogel patches, and wearable electronics. However, the preparation process of the bilayer materials usually involves several complicated steps and is time-consuming, while the interfacial bonding is another main concern. Here, a simple and versatile method is proposed to obtain bilayer hydrogels within just one step based on the method of introducing viscosity contrast of the precursors for different layers. The bilayer structure can be well maintained during the whole preparation process with a constrained interfacial molecular exchange to ensure the strong bonding strength. The key requirements for forming distinct bilayer structures in situ are studied and discussed in detail. Bilayer hydrogels with different chemical designs are prepared via this strategy to tailor the good distribution of desired functions for soft actuators, wound healing patches, and wearable electronics. We believe that the strategy illustrated here will provide new insights into the preparation and application of bilayer materials.