Dynamic Color-Switching of Hydrogel Micropillar Array under Ethanol Vapor for Optical Encryption.

Responsive structural colors from artificially engineered micro/nanostructures are critical to the development of anti-counterfeiting, optical encryption, and intelligent display. Herein, the responsive structural color of hydrogel micropillar array is demonstrated under the external stimulus of ethanol vapor. Micropillar arrays with full color are fabricated via femtosecond laser direct writing by controlling the height and diameter of the micropillars according to the FDTD simulation. Color-switching of the micropillar arrays is achieved in <1 s due to the formation of liquid film among micropillars. More importantly, the structural color blueshift of the micropillar arrays is sensitive to the micropillar diameter, instead of the micropillar height. The micropillar array with a diameter of 772 nm takes 400 ms to complete blueshift under ethanol vapor, while that with a diameter of 522 nm blueshifts at 2400 ms. Microscale patterns are realized by employing the size-dependent color-switching of designed micropillar arrays under ethanol vapor. Moreover, Morse code and directional blueshift of structural colors are realized in the micropillar arrays. The advantages of controllable color-switching of the hydrogel micropillar array would be prospective in the areas of optical encryption, dynamic display, and anti-counterfeiting.

Dual-Stimuli Cooperative Responsive Hydrogel Microactuators Via Two-Photon Lithography.

With the development of bionics as well as materials science, intelligent soft actuators have shown promising applications in many fields such as soft robotics, sensing, and remote manipulation. Microfabrication technologies have enabled the reduction of the size of responsive soft actuators to the micron level. However, it is still challenging to construct microscale actuators capable of responding to different external stimuli in complex and diverse conditions. Here, this work demonstrates a dual-stimuli cooperative responsive hydrogel microactuator by asymmetric fabrication via femtosecond laser direct writing. The dual response of the hydrogel microstructure is achieved by employing responsive hydrogel with functional monomer 2-(dimethylamino)ethyl methacrylate. Raman spectra of the hydrogel microstructures suggest that the pH and temperature response of the hydrogel is generated by the changes in tertiary amine groups and hydrogen bonds, respectively. The asymmetric hydrogel microstructures show opposite bending direction when being heated to high temperature or exposed to acid solution, and can independently accomplish the grasp of polystyrene microspheres. Moreover, this work depicts the cooperative response of the hydrogel microactuator to pH and temperature at the same time. The dual-stimuli cooperative responsive hydrogel microactuators will provide a strategy for designing and fabricating controllable microscale actuators with promising applications in microrobotics and microfluidics.

Clay-Originated Two-Dimensional Holey Silica Separator for Dendrite-Free Lithium Metal Anode.

Lithium metal anode is the ultimate choice to obtain next-generation high-energy-density lithium batteries, while the dendritic lithium growth owing to the unstable lithium anode/electrolyte interface largely limits its practical application. Separator is an important component in batteries and separator engineering is believed to be a tractable and effective way to address the above issue. Separators can play the role of ion redistributors to guide the transport of lithium ions and regulate the uniform electrodeposition of Li. The electrolyte wettability, thermal shrinkage resistance, and mechanical strength are of importance for separators. Here, clay-originated two-dimensional (2D) holey amorphous silica nanosheets (ASN) to develop a low-cost and eco-friendly inorganic separator is directly adopted. The ASN-based separator has higher porosity, better electrolyte wettability, much higher thermal resistance, larger lithium transference number, and ionic conductivity compared with commercial separator. The large amounts of holes and rich surface oxygen groups on the ASN guide the uniform distribution of lithium-ion flux. Consequently, the Li//Li cell with this separator shows stable lithium plating/stripping, and the corresponding Li//LiFePO4 , Li//LiCoO2, and Li//NCM523 full cells also show high capacity, excellent rate performance, and outstanding cycling stability, which is much superior to that using the commercial separator.

Expression of circulating microRNA-20a and let-7a in esophageal squamous cell carcinoma.

AIM: To investigate the expressions of microRNA-20a (miR-20a) and let-7a in esophageal squamous cell carcinoma (ESCC) and their diagnostic value. METHODS: Seventy patients with ESCC and 40 healthy subjects were enrolled to investigate the expression of miR-20a and let-7a using quantitative real-time PCR. The expression of miR-20a and let-7a was compared between ESCC patients and healthy subjects. The plasma levels of miR-20a and let-7a in relation to patient clinicopathologic parameters, the receiver operating characteristic (ROC) curve, and the sensitivity and specificity of miR-20a and let-7a in ESCC diagnosis were analyzed. RESULTS: Plasma levels of miR-20a were significantly higher in ESCC patients than in healthy controls, and plasma levels of let-7 were lower in ESCC patients than in healthy controls (both P < 0.05). The area under the ROC curve of miR-20a was 0.767 (95%CI: 0.677-0.857; P < 0.001), when the cut-off value was set at 4.77, the sensitivity and specificity were 64.3% and 75.0%, respectively. The area under the ROC curve of let-7a was 0.829 (95%CI: 0.754-0.904; P < 0.001), when the cut-off value was set at 6.22, the sensitivity and specificity were 74.3% and 85.0%, respectively. Thus, the sensitivity and specificity of let-7a were higher than those of miR-20a. The median relative plasma expression of let-7a in clinical stage III/IV (0.24) was lower than that in stage I/II (0.42), while the expression of miR-20a according to stage was not statistically different. The expressions of miR-20a and let-7a were not related to gender, age, tumor diameter, tumor grade, or pathologic stage. CONCLUSION: Plasma miR-20a and let-7a levels are significantly altered in patients with ESCC and can be used as potential biomarkers in the diagnosis of ESCC.

Hypoglycemic efficacy of pulmonary delivered insulin dry powder aerosol in rats.

AIM: To observe the hypoglycemic efficacy of pulmonary delivery of insulin in dry powder aerosol form. METHODS: Insulin dry powder, made of insulin and other proper materials, was insufflated in rat lung from an incision in the throat. Meanwhile, insulin injection was administered to other rats. Glucose concentration in blood was determined in the following 7 h. The areas above the curve (AAC) of glucose concentration in blood were used to evaluate the efficacy. RESULTS: The percent minimum blood glucose levels, compared with the glucose levels before the administration, for pulmonary deliver ed insulin at the doses of 20, 10, 5, and 2.5 U/kg were 6.5 %, 16.6 %, 24.6 %, and 57.0 %, respectively. The AAC of insulin 5 U/kg by pulmonary delivery was very close to that of subcutaneous administration at the same dose. There was a linear relationship between AAC and the logarithmic dose of pulmonary delivered insulin. CONCLUSION: The pulmonary delivery of insulin acts effectively and rapidly.

[HPLC determination of insulin and its related substances in insulin powder for inhalation].

AIM: To determine insulin and its related substances in insulin powder for inhalation by reversed phase high performance liquid chromatography method. METHODS: The initial mobile phase was solution A (0.1% trifluoroacetic acid-acetonitril 70:30) and changed to solution B (0.1% trifluoroacetic acid-acetonitril 60:40) in 30 minutes. The flow rate was 2.0 mL.min-1, the column temperature was 30 degrees C, the wave length was 280 nm, the injected volume was 20 microL. RESULTS: Insulin was well separated from other peaks induced in different conditions. There was good linear relationship between the amount of insulin and its peak area, the RSD was 1.1%, the insulin solution for determination was stable in 12 hours, and the quantity detected was near the added. CONCLUSION: The method is simple and accurate to detect insulin and its related substances in insulin and its preparations.