Programmable Thermo-Responsive Actuation of Hydrogels via Light-Guided Surface Growth of Active Layers on Shape Memory Substrates.

Hydrogel shape memory and actuating functionalities are heavily pursued and have found great potential in various application fields. However, their combination for more flexible and complicated morphing behaviors is still challenging. Herein, it is reported that by controlling the light-initiated polymerization of active hydrogel layers on shape memory hydrogel substrates, advanced morphing behaviors based on programmable hydrogel shapes and actuating trajectories are realized. The formation and photo-reduction-induced dissociation of Fe3+ -carboxylate coordination endow the hydrogel substrates with the shape memory functionality. The photo-reduced Fe2+ ions can diffuse from the substrates into the monomer solutions to initiate the polymerization of the thermally responsive active layers, whose actuating temperatures and amplitudes can be facially tuned by controlling their thicknesses and compositions. One potential application, a shape-programmable 3D hook that can lift an object with a specific shape, is also unveiled. The demonstrated strategy is extendable to other hydrogel systems to realize more versatile and complicated actuating behaviors.

Thermal-Responsive Hydrogel Actuators with Photo-Programmable Shapes and Actuating Trajectories.

Thermal-responsive hydrogel actuators have aroused a wide scope of research interest and have been extensively studied. However, their actuating behaviors are usually monotonous due to their unchangeable shapes and structures. Here, we report thermal-responsive poly(isopropylacrylamide-co-2-(dimethylamino)ethyl methacrylate)/alginate hydrogels with programmable external shapes and internal actuating trajectories. The volume phase transition temperatures of the resulting hydrogels can be tuned in a wide temperature range from 32 to above 50 °C by adjusting the monomer composition. While the formation and photo-dissociation of Fe3+-carboxylate tri-coordinates within the entire hydrogel network enable photo-responsive shape memory property, the insufficient dissociation of the tri-coordinates along the irradiation path gives rise to gradient crosslinking for realizing thermal-responsive actuation. Controlling the evolution of the gradient structure facilitates the regulation of the actuating amplitude. Furthermore, we show that the combination of these two types of shape-changing functionalities leads to more flexible and intricate shape-changing behaviors. One interesting application, a programmable hook with changeable actuating behaviors for lifting different objects with specific shapes, is also demonstrated. The proposed strategy can be extended to other types of actuating hydrogels with more advanced actuating behaviors.

Effects of laparoscopic radical surgery in the treatment of colorectal cancer and correlations of VEGF and TGF-ß1 with prognosis.

OBJECTIVE: To investigate the effects of laparoscopic radical surgery on the treatment of colorectal cancer (CRC) and explore the correlations of vascular endothelial growth factor (VEGF) and transforming growth factor-ß1 (TGF-ß1) with prognosis. METHODS: The clinical data of 210 patients with CRC admitted to the Yantai Zhifu Hospital from February 2015 to February 2018 were analyzed retrospectively. Among them, 110 patients were treated with laparoscopic radical surgery and assigned to the observation group, and the rest 100 patients were treated with routine open surgery and included in the open group. The two groups were compared in terms of operation time (OT), intraoperative blood loss (IBL), postoperative exhaust time (PET), length of hospital stays (LOS) and incidence of complications. Patients were also followed up for 3 years to count their survival rates. Serum expression levels of VEGF and TGF-ß1, detected by enzyme-linked immunosorbent assays (ELISAs), were compared before and after treatment, and their correlations with patients' clinicopathological data and prognosis were analyzed. RESULTS: Compared with the open group, patients in the observation group had longer OT, but lower IBL, PET, LOS, and overall incidence of complications. In the observation group, VEGF and TGF-ß1 expression after treatment was remarkably lower than that before treatment and that in the open group. A 3-year survival rate of 80.0% was observed in the observation group. Univariate analysis showed that serum VEGF and TGF-ß1 expression levels were closely related to Dukes staging and lymph node metastasis (LNM) (P<0.05). The Log-Rank test showed that the survival rate of patients with high VEGF and TGF-ß1 expression was remarkably lower than that of those with low expression (P<0.05). According to Cox model multivariate analysis, Dukes staging, LNM, surgical methods and high VEGF and TGF-ß1 expression were all independent risk factors for the prognosis of CRC patients (P<0.05). CONCLUSION: Laparoscopic radical surgery is effective and safe in treating CRC. VEGF and TGF-ß1 are highly expressed in the serum of CRC patients, and are closely related to the tumor staging, LNM and prognosis of patients, which are of great significance for evaluating the condition and prognosis of CRC patients.