Bioinspired Flexible Hydrogelation with Programmable Properties for Tactile Sensing.

Tactile sensing requires integrated detection platforms with distributed and highly sensitive haptic sensing capabilities along with biocompatibility, aiming to replicate the physiological functions of the human skin and empower industrial robotic and prosthetic wearers to detect tactile information. In this regard, short peptide-based self-assembled hydrogels show promising potential to act as bioinspired supramolecular substrates for developing tactile sensors showing biocompatibility and biodegradability. However, the intrinsic difficulty to modulate the mechanical properties severely restricts their extensive employment. Herein, by controlling the self-assembly of 9-fluorenylmethoxycarbonyl-modifid diphenylalanine (Fmoc-FF) through introduction of polyethylene glycol diacrylate (PEGDA), wider nanoribbons are achieved by untwisting from well-established thinner nanofibers, and the mechanical properties of the supramolecular hydrogels can be enhanced 10-fold, supplying bioinspired supramolecular encapsulating substrate for tactile sensing. Furthermore, by doping with poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and 9-fluorenylmethoxycarbonyl-modifid 3,4-dihydroxy-l-phenylalanine (Fmoc-DOPA), the Fmoc-FF self-assembled hydrogels can be engineered to be conductive and adhesive, providing bioinspired sensing units and adhesive layer for tactile sensing applications. Therefore, the integration of these modules results in peptide hydrogelation-based tactile sensors, showing high sensitivity and sustainable responses with intrinsic biocompatibility and biodegradability. The findings establish the feasibility of developing programmable peptide self-assembly with adjustable features for tactile sensing applications.

Heterogeneous-Nucleation Biosensor for Long-Term Collection and Mask-Based Self-Detection of SARS-CoV-2.

The effective control of infectious diseases, including Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection, depends on the availability of rapid and accurate monitoring techniques. However, conventional SARS-CoV-2 detection technologies do not support continuous self-detection and may lead to cross-infection when utilized in medical institutions. In this study, we introduce a prototype of a mask biosensor designed for the long-term collection and self-detection of SARS-CoV-2. The biosensor utilizes the average resonance Rayleigh scattering intensity of Au nanocluster-aptamers. The inter-mask surface serves as a medium for the long-term collection and concentration enhancement of SARS-CoV-2, while the heterogeneous-nucleation nanoclusters (NCs) contribute to the exceptional stability of Au NCs for up to 48 h, facilitated by the adhesion of Ti NCs. Additionally, the biosensors based on Au NC-aptamers exhibited high sensitivity for up to 1 h. Moreover, through the implementation of a support vector machine classifier, a significant number of point signals can be collected and differentiated, leading to improved biosensor accuracy. These biosensors offer a complementary wearable device-based method for diagnosing SARS-CoV-2, with a limit of detection of 103 copies. Given their flexibility, the proposed biosensors possess tremendous potential for the continuous collection and sensitive self-detection of SARS-CoV-2 variants and other infectious pathogens.

Aspect Ratio Effects on the Aerodynamic Performance of a Biomimetic Hummingbird Wing in Flapping.

Hummingbirds are flapping winged creatures with unique flight mechanisms. Their flight pattern is more similar to insects than other birds. Because their flight pattern provides a large lift force at a very small scale, hummingbirds can remain hovering while flapping. This feature is of high research value. In order to understand the high-lift mechanism of hummingbirds' wings, in this study a kinematic model is established based on hummingbirds' hovering and flapping process, and wing models imitating the wing of a hummingbird are designed with different aspect ratios. Therefore, with the help of computational fluid dynamics methods, the effect of aspect ratio changes on the aerodynamic characteristics of hummingbirds' hovering and flapping are explored in this study. Through two different quantitative analysis methods, the results of lift coefficient and drag coefficient show completely opposite trends. Therefore, lift-drag ratio is introduced to better evaluate aerodynamic characteristics under different aspect ratios, and it is found that the lift-drag ratio reaches a higher value when AR = 4. A similar conclusion is also reached following research on the power factor, which shows that the biomimetic hummingbird wing with AR = 4 has better aerodynamic characteristics. Furthermore, the study of the pressure nephogram and vortices diagram in the flapping process are examined, leading to elucidation of the effect of aspect ratio on the flow field around hummingbirds' wings and how these effects ultimately lead to changes in the aerodynamic characteristics of the birds' wings.

Systematic design of cell membrane coating to improve tumor targeting of nanoparticles.

Cell membrane (CM) coating technology is increasingly being applied in nanomedicine, but the entire coating procedure including adsorption, rupture, and fusion is not completely understood. Previously, we showed that the majority of biomimetic nanoparticles (NPs) were only partially coated, but the mechanism underlying this partial coating remains unclear, which hinders the further improvement of the coating technique. Here, we show that partial coating is an intermediate state due to the adsorption of CM fragments or CM vesicles, the latter of which could eventually be ruptured under external force. Such partial coating is difficult to self-repair to achieve full coating due to the limited membrane fluidity. Building on our understanding of the detailed coating process, we develop a general approach for fixing the partial CM coating: external phospholipid is introduced as a helper to increase CM fluidity, promoting the final fusion of lipid patches. The NPs coated with this approach have a high ratio of full coating (~23%) and exhibit enhanced tumor targeting ability in comparison to the NPs coated traditionally (full coating ratio of ~6%). Our results provide a mechanistic basis for fixing partial CM coating towards enhancing tumor accumulation.

Cardioprotective Mechanism of Leonurine against Myocardial Ischemia through a Liver-Cardiac Crosstalk Metabolomics Study.

Leonurine has been shown to have excellent anti-myocardial ischemia effects. Our previous studies suggested that cardiac protection by leonurine during myocardial ischemia appeared to be inextricably linked to its regulation of the liver. At present, however, there are few mechanistic studies of leonurine and its regulation of hepatic metabolism against ischemic injury. In this study, a metabolomics approach was developed to give a global view of the metabolic profiles of the heart and liver during myocardial ischemia. Principal component analysis and orthogonal partial least squares discrimination analysis were applied to filter differential metabolites, and a debiased sparse partial correlation analysis was used to analyze the correlation of the differential metabolites between heart and liver. As a result, a total of thirty-one differential metabolites were identified, six in the myocardial tissue and twenty-five in the hepatic tissue, involving multiple metabolic pathways including glycine, serine and threonine, purine, fatty acid, and amino acid metabolic pathways. Correlation analysis revealed a net of these differential metabolites, suggesting an interaction between hepatic and myocardial metabolism. These results suggest that leonurine may reduce myocardial injury during myocardial ischemia by regulating the metabolism of glycine, serine and threonine, purine, fatty acids, and amino acids in the liver and heart.

Antibody-Functional Microsphere-Integrated Filter Chip with Inertial Microflow for Size-Immune-Capturing and Digital Detection of Circulating Tumor Cells.

Circulating tumor cells (CTCs) in blood is the direct cause of tumor metastasis. The isolation and detection of CTCs in the whole blood is very important and of clinical value in early diagnosis, postoperative review, and personalized treatment. It is difficult to separate all types of CTCs that efficiently rely on a single path due to cancer cell heterogenicity. Here, we designed a new kind of "filter chip" for the retention of CTCs with very high efficiency by integrating the effects of cell size and specific antigens on the surface of tumor cells. The filter chip consists of a semicircle arc and arrays and can separate large-scale CTC microspheres, which combined with CTCs automatically. We synthesized interfacial zinc oxide coating with nanostructure on the surface of the microsphere to increase the specific surface area to enhance the capturing efficiency of CTCs. Microspheres, trapped in the arrays, would entrap CTCs, too. The combination of the three kinds of strategies resulted in more than 90% capture efficiency of different tumor cell lines. Furthermore, it is easy to find and isolate the circulating tumor cells from the chip as tumor cells would be fixed inside the structure of a filter chip. To avoid the high background contamination when a few CTCs are surrounded by millions of nontarget cells, a digital detection method was applied to improve the detection sensitivity. The CTCs in the whole blood were specifically labeled by the antibody-DNA conjugates and detected via the DNA of the conjugates with a signal amplification. The strategy of the antibody-functional microsphere-integrated microchip for cell sorting and detection of CTCs may find broad implications that favor the fundamental cancer biology research, the precise diagnosis, and monitoring of cancer in the clinics.

Highly convergent synthesis of a ß-mannuronic acid alginate hexadecasaccharide.

Solution-phase synthesis of poly-ß-mannuronic acids still remains unexplored. We report the first synthesis of a ß-mannuronic acid alginate hexadecasaccharide representing the longest synthetic polymannuronic acid so far. The highly convergent synthetic approach provides a new avenue to access poly-ß-mannuronic acids that can enable the biological evaluation of poly-ß-mannuronic acids as potential therapeutics and vaccines.

Bioinspired Shear-Flow-Driven Layer-by-Layer in Situ Self-Assembly.

Layer-by-layer (LbL) assembly is widely applied as a coating technique for the nanoscale control of architecture and related properties. However, its translational applications are limited by the time-consuming and laborious nature of the process. Inspired by the blood-clotting process, herein, we develop a shear-flow-driven LbL (SF-LbL) self-assembly approach that accelerates the adsorption rate of macromolecules by mechanically configuring the polymer chain via a coil-stretch transition, which effectively simplifies and speeds the diffusion-controlled assembly process. The structural characteristics and surface homogeneity of the SF-LbL films are improved, and diverse three-dimensional structures can be achieved. Functional SF-LbL-assembled surfaces for corneal modification are successfully fabricated, and the surface of wounded rat corneas and skin can be directly decorated in situ with SF-LbL nanofilms due to the advantages of this approach. Furthermore, in situ SF-LbL self-assembly has promise as a simple approach for the wound dressing for interventional therapeutics in the clinic, as illustrated by the successful in situ fabrication of drug-free layers consisting of chitosan and heparin on the dorsal skin of diabetic mice to rescue defective wound healing. This bioinspired self-assembly approach is expected to provide a robust and versatile platform with which to explore the surface engineering of nanofilms in science, engineering, and medicine.

Application of Berendsen barostat in dissipative particle dynamics for nonequilibrium dynamic simulation.

The Berendsen barostat from molecular dynamics simulation is applied in both standard dissipative particle dynamics (DPD) and many-body dissipative particle dynamics (MDPD) simulations. The original Berendsen barostat works well in (M)DPD simulation of a single-component system under constant pressure condition and in nonequilibrium dynamic processes. The partial Berendsen barostat is proposed for multi-component system simulation with (M)DPD. The displacement rescaling process of the Berendsen barostat is only applied on the particles outside the center region, acting as a pressure "boundary condition." The center part forms the free zone, in which the interface shape and nonequilibrium dynamic behavior between different phases can be captured properly. An immiscible bubble in the second fluid under constant pressure condition is studied, and the oscillation of the bubble radius and fluctuation of systempressure can be obtained by the current barostat. Preliminary models for bubble growing and collapsing under square pressure wave and bubble oscillation under harmonic pressure wave are also reported in the current simulation. It shows that the partial Berendsen barostat is suitable for the modeling of nonequilibrium process of single or few droplets/bubbles in multi-component systems.

[Effects of ferulic acid on the expressions of nephrin and podocin in podocytes of diabetic rats].

OBJECTIVE: To investigate the effects of ferulic acid (FA) on the streptozocin (STZ) -induced kidney injury in diabetic rats and its possible mechanisms. METHODS: Diabetes was induced in male SD rats by an injection of STZ (40 mg/kg,i.v.). After 72 hours, blood glucose levels were detected and blood glucose levels exceeded 16.7 mmol/L were diagnosed as diabetic model rats. Diabetic model rats were randomly divided into model group and FA group, ten animal in each group. Another 10 healthy male SD rats were treated as control group. The rats in FA group were treated with FA (100 mg/kg, i.g.,qd) from the 5th week since the diabetic rats model was successfully established and lasted for 8 weeks. The levels of blood glucose, body weight, organ coefficient of kidney, blood urea nitrogen and creatinine were tested. HE staining was employed to observe the pathological changes of the renal tissue. Immunohistochemistry was employed to determine the protein of nephrin and podocin. RESULTS: Compared to control group, the levels of blood glucose, organ coefficient of kidney, blood urea nitrogen(BUN) and serum creatinine(sCr) were increased significantly. Renal cells from model group rats showed atrophied and disordered after HE staining and interstitial proliferation were also appeared in renal tissue of the model group. Meantime, the levels of nephrin and podocin protein were obviously decreased. These changes were significantly attenuated in the model group treated with FA. CONCLUSIONS: FA can evidently ameliorate renal damage in rats with diabetic nephropathy induced by STZ, which might be related to increase the level of nephrin and podocin protein.

[Protective effect of total flavonoids of epimedium on the kidney in experimental diabetic rats].

OBJECTIVE: To investigate the influence of total flavonoids of epimedium (TFE) on the streptozocin (STZ)-induced kidney injury in diabetic rats and discuss the possible mechanism. METHODS: Diabetes was produced by a single injection of streptozocin (40 mg/kg, iv) in male SD rats. The rats were randomly divided into three groups (n = 10): control group, model group and TFE group (100 mg/kg, ig). Animals were sacrificed 12 weeks later. The level of blood glucose, blood urea nitrogen (BUN) and creatinine (Cr) as well as the renal index were determined. Detect the specific biochemical of renal tissue: superoxide dismutase (SOD), malondialdehyde (MDA). Use masson staining to observe the morphology of the renal tissue. Immunohistochemistry was employed to determine the protein levels of transforming growth factor-beta1 (TGF-beta1). RESULTS: Compared to control group, the enhancement of blood glucose, renal index, BUN and Cr was found in model group, which was significantly attenuated by treatment with TFE. Meanwhile, elevated MDA level in renal tissue as well as decreased SOD activities in renal tissue were significantly remitted by TFE. Furthermore, TFE decreased the expression of TGF-beta1. CONCLUSION: TFE can evidently relieve renal damage in rats with diabetic nephropathy induced by STZ, which might be related to antioxidation and modulating the expression of TGF-beta1 protein.

[Study on the protective effect of ursolic acid on alloxan-induced diabetic renal injury and its underlying mechanisms].

OBJECTIVE: To investigate the effect of ursolic acid (UA) on the alloxan-induced kidney injury in diabetic mice and explored its possible mechanisms. METHODS: Diabetes mellitus was induced in male Kunming mice by an injection of alloxan (70 mg/kg, i.v.). After 72 hours, blood glucose levels were detected and mice with blood glucose levels over 13.9 mmol/L were considered as diabetic and selected for further experiment. Thirty mice were randomly divided into three groups: control, diabetic and diabetic + UA(35 mg/kg/d, i.g. continuously for 8 weeks). Blood glucose concentration, organ coefficient of kidney, blood urea nitrogen (BUN), creatinine (Cr) as well as renal tissue levels of superoxide dismutase (SOD), methane dicarboxylic aldehyde (MDA), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were determined. Pathology of the renal tissue was measured by hematoxylin-eosin staining. RESULTS: Compared to the control group, blood glucose, organ coefficient of kidney, BUN and Cr increased significantly. In addition, SOD activities was reduced markedly and levels of MDA and inflammatory factors (TNF-α, IL-6) increased significantly. Renal cells from model group rats showed atrophy and disordered after HE staining and infiltration of inflammatory cells also appeared in renal tissue of the model group. These changes were significantly attenuated in the diabetic group treated with UA. CONCLUSION: UA can significantly relieve renal damage in mice with diabetic nephropathy induced by alloxan, which might be related to decreased blood glucose level, antioxidation effect and inhibiting the production of inflammatory factors such as TNF-α and IL-6.