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Most medicines are coming with toxic and detrimental side effects. In addition, microbials are resisting the medicine. Therefore, alternative drugs with low toxic and side effects and low microbial resistance are needed. Plants offer good potential candidates due to a broad range of chemicals they contain. These chemicals have been studied, and research is still going on to probe chemical properties of plant chemicals. In China, traditional Chinese medicine is practised, whereby plant extracts are obtained, and then sold in packages for reasons like memory enhancement, cancer treatment, boosting immune system, and so on. Among the herbs cultivated in China is Polygonati rhizoma (PGR). This plant contains various bioflavonoids such as diosgenin, kaempferol, catechin, daidzein, and 3 ′ -methoxydaidzein. In this review, we discussed the pharmacological effects of these chemicals, including luteolin antimicrobial activity in a manner that it circumvents antibiotic resistance; rutin antivenom property; kaempferol as an agent that mitigates neuropathic pain; genistein anticancer property; isorhamnetin’s ability to alleviate chronic obstructive pulmonary diseases (COPD); proanthocyanidins’ ability to deal with diabetic neuropathy and analgesic property of catechin.

Biological 3D printing is a reliable technology for 3D printing bone repair scaffolds with simple operation, high efficiency, and relatively low cost. Gelatin methacryloyl (GelMA) hydrogels have attracted much attention due to their good biocompatibility, but the poor mechanical properties limit their application in bone reconstruction engineering. In this study, nano-hydroxyapatite (nHA) particles were added to GelMA hydrogels, and the performances of composite hydrogel scaffolds with different nHA contents were investigated in terms of rheological properties, light transmission properties, surface morphology, mechanical properties, and biocompatibility. The experimental results showed that the incorporation of nHA particles could effectively improve the printability and mechanical properties of the scaffolds, the scaffold fibers had better resistance to deformation, improved degradation rate, and biological experiments confirmed that nHA particles had no significant cytotoxicity. However, the addition of HA particles also reduced the light transmission properties of the slurry, and when its content exceeds a certain value, the hydrogel scaffolds show incomplete curing and eventually affect their test performance. The results can offer guidance and reference for the selection of ink and function for 3D printing bone repair scaffold.

The high strength, elasticity, hardness and wear resistance of C17200 copper means it is widely used in motor brushes, bearing sleeves and contact parts. As the requirement for extended reliability and service life of industrial products increases, the demand for high-performance copper-beryllium (Cu-Be) will also increase. In this work, the wear mechanisms of C17200 alloy against GCr15 steel under dry conditions and in a 3.5% NaCl solution were investigated. X-ray diffractometry, scanning electron microscopy, energy-dispersive x-ray spectroscopy, a three-dimensional profilometer, and x-ray photoelectric spectroscopy were used to evaluate the wear damage and analyze the wear mechanisms involved. The results showed that the wear mechanisms of C17200 alloy under dry wear conditions were mainly adhesive wear, oxidation wear and delamination. During tribocorrosion, the effect of friction promoted the oxidation and corrosion of the specimen surface. The main wear mechanisms of tribocorrosion in a 3.5% NaCl solution were peeling and corrosion wear. In addition, the NaCl solution provided lubrication and could effectively reduce the wear of the materials. The results may guide improvement of the serviceability of Cu-Be materials in industrial environments.

The micromechanical properties of soft tissue can be used as markers for the physiological state and function of the tissue. Deep understanding of the micromechanics of soft tissue, such as the oesophagus, is of great significance to the design of artificial oesophagi, endoscope materials and coatings for medical devices. Here, the micromechanical properties of oesophageal mucosa were studied under different loading rates, deflections, and dwell time by using atomic force microscopy. The micromechanical properties of soft tissue included elastic modulus, plasticity and adhesion force. Results showed that the micromechanical properties changed with increasing loading rate, deflection and dwell time. The micromechanical properties of oesophageal mucosa were related to time-dependent behaviours, such as contact stress, energy transformation, and strain gradient plasticity. Furthermore, the heterogeneity of oesophageal mucosa affected the micromechanical properties. The force mapping mode was a reliable and effective means to study the micromechanical properties of soft tissue. The results can provide a basis and technical support for the diagnosis of oesophageal diseases from a microscale as well as a material design perspective.

Biomaterials employed in the articular joint cavity, such as polycarbonate urethane (PCU) for meniscus replacement, lack of lubrication ability, leading to pain and tissue degradation. We present a nanostructured adhesive coating based on dopamine-modified hyaluronan (HADN) and poly-lysine (PLL), which can reestablish boundary lubrication between the cartilage and biomaterial. Lubrication restoration takes place without the need of exogenous lubricious molecules but through a novel strategy of recruitment of native lubricious molecules present in the surrounding milieu. The biomimetic adhesive coating PLL-HADN (78 nm thickness) shows a high adhesive strength (0.51 MPa) to PCU and a high synovial fluid responsiveness. The quartz crystal microbalance with dissipation monitoring shows the formation of a thick and softer layer when these coatings are brought in contact with the synovial fluid. X-ray photoelectron spectroscopy and ConA-Alexa staining show clear signs of lubricious protein (PRG4) recruitment on the PLL-HADN surface. Effective recruitment of a lubricious protein by PLL-HADN caused it to dissipate only one-third of the frictional energy as compared to bare PCU when rubbed against the cartilage. Histology shows that this reduction makes the PLL-HADN highly chondroprotective, whereas PLL-HA coatings still show signs of cartilage wear. Shear forces in the range of 0.07-0.1 N were able to remove âˆ80% of the PRG4 from the PCU-PLL-HA but only 27% from the PCU-PLL-HADN. Thus, in this study, we have shown that surface recruitment and strong adsorption of biomacromolecules from the surrounding milieu is an effective biomaterial lubrication strategy. This opens up new possibilities for lubrication system reconstruction for medical devices.

Despite the fact that transcatheter cardiovascular interventions are increasingly prevalent nowadays, friction damage caused by mechanical interaction between blood vessel and cardiovascular catheter limit their therapeutic utility. Based on dopamine-modified hyaluronic (HA-DN) acid and chitosan (CHI), a layer-by-layer lubricating coating for cardiovascular catheters was designed and assessed in this work. Results showed that the CHI/HA-DN composite coatings became more hydrophilic as the deposition layers were increased. The (CHI/HA-DN)

Conventional bone repair scaffolds can no longer meet the high standards and requirements of clinical applications in terms of preparation process and service performance. Studies have shown that the diversity of filament structures of implantable scaffolds is closely related to their overall properties (mechanical properties, degradation properties, and biological properties). To better elucidate the characteristics and advantages of different filament structures, this paper retrieves and summarizes the state of the art in the filament structure of the three-dimensional (3D) bioprinted biodegradable bone repair scaffolds, mainly including single-layer structure, double-layer structure, hollow structure, core-shell structure and bionic structures. The eximious performance of the novel scaffolds was discussed from different aspects (material composition, ink configuration, printing parameters, etc.). Besides, the additional functions of the current bone repair scaffold, such as chondrogenesis, angiogenesis, anti-bacteria, and anti-tumor, were also concluded. Finally, the paper prospects the future material selection, structural design, functional development, and performance optimization of bone repair scaffolds.

Hydrophilic lubricious coatings on the catheter surface reduce friction against the blood vessel wall but give rise to iatrogenic complication of particle release, embolization and thin blood vessel blockage leading to pulmonary infarction and stroke. Layer by layer deposited PLL (poly- l -lysine) and HA (hyaluronan) coating fills the urgent need of thinner lubricious coating which does not lead to release of large particles. The 8 layered PLL-HA coating was able to maintain low friction and prevent wear of endothelial glycocalyx layer (EGL). Wear and loss of EGL is a gradual process and occurred while sliding the blood vessel against bare catheter surface or 4 layered coating accompanied by epithelial cells damage and decrease in the number of nucleuses.

Catheterization is a common medical operation for cardiovascular disease diagnosis and treatment, where low friction is attained through hydrophilic lubricious coatings. But these coatings can cause iatrogenic complications when particles become lose and float freely in the blood stream. Here we present an ultra-thin coating based on polyethylene glycol (PEG) functionalized hyaluronic acid (HA). The mussel-inspired biopolymer hyaluronic acid was first conjugated to dopamine (DN) to get HADN and then poly (ethylene glycol) bis (3-amino-propyl) terminated (PBA) was used to functionalize the HADN with PEG. The reciprocating sliding ball-on-flat ex vivo model based on PU ball and porcine aorta was used to evaluate the lubrication performance and the results suggest coating of HADN with best lubrication enhancement. After 40 min friction test, the surface of aorta remained intact for HADN-PBA coated PU as compared to HADN coating and positive control (sliding against bare PU). The amount of glycocalyx, number of endothelial nuclei and intima surface of aorta for coated PU were similar to negative control (without rubbing). Besides lubrication, the high biocompatibility suggests the coating of HADN-PBA is safe and lubrication benefits to the cardiovascular catheter. (c) 2020 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).

Purpose: Endoscopy is a common and effective method to treat digestive system diseases. Not only can it detect the physiological state of the digestive tract, but also can conduct clinical operations. As a result, it’s of great significance to make clear the relationship between the clinical operation and the complications. Methods: Considering the difficulty in measuring the contact force and determining the stress distribution in real time during endoscopy, a specific-patient finite element model for the frictional behavior at the endoscope-esophagus interface was built in current study. By collecting the CT data of the patient, a 3D esophagus model was built and divided into three characteristic regions (narrow region, thoracic region and abdominal region) according to the physiological structure. Results: Results showed that the radius of the narrowest position was the dominant factor for the maximum von Mises stress when the endoscope passed through the narrow region. For abdominal region and thoracic region, with the increasing coefficient of friction (COF) and amplitude, the total force duo to frictional force (CFSM), frictional dissipation (FD), strain energy (SE) and maximum von Mises stress (Max) all increased correspondingly. Meanwhile, the region of stress concentration gradually approached the initial contact stage. Conclusions: The results can provide theoretical basis and technical support for clinical application and offer some suggestions for medical workers during endoscopy as well.

The mucous layer on the surface of human digestive tract is a dynamically balanced protective system, mainly containing mucin, enzymes, bicarbonate, epidermal growth factor and other protective factors. It has been found that mucins can protect epithelial cells from infection, dehydration, and physical, mechanical or chemical damage. There are a variety of disturbances that affect or destroy the function of the mucous layer, including mucus dysfunction and diseases of digestive tract. In this paper, the mechanical function of mucin on the surface of esophagus was studied using the UMT Tribometer with the porcine esophagus as the experiment sample. Trypsin was used to control the mucin content on the surface of esophagus. Results showed that the trypsin can affect the function of the mucin on the surface of esophagus. The friction coefficient and the relevant energy dissipation of trypsin-treated and non-trypsin-treated samples were significantly different. Due to the reduction of mucin on the esophageal surface by trypsin treatment, the friction coefficient and energy dissipation of the esophageal surface were significantly higher than that of the samples without trypsin treatment. During the friction test, the esophagus surface was severely damaged at both macro and micro scales after trypsin treatment, which indicated that the mucin can play a lubrication role at the gastroscope device-esophagus interface. The results can provide reference for clinical endoscopic examination and medical advice for clinical practice.

Catheterization is a common medical operation to diagnose and treat cardiovascular diseases. The blood vessel lumen is coated with endothelial glycocalyx layer (EGL), which is important for the permeability and diffusion through the blood vessels wall, blood hemodynamics and mechanotransduction. However EGL’s role in catheter-blood vessel friction is not explored. We use a porcine aorta to mimic the blood vessel and a catheter loop was made to rub in reciprocating sliding mode against it to understand the role of catheter loop curvature, stiffness, normal load, sliding speed and EGL on the friction properties. Trypsin treatment was used to cause a degradation of the EGL. Decrease in catheter loop stiffness and EGL degradation were the strongest factors which dramatically increased the coefficient of friction (COF) and frictional energy dissipation at the aorta-catheter interface. Increasing sliding speed caused an increase but increase in normal load first caused a decrease and then an increase in the COF and frictional energy. These results provide the basic data for safety of operation and damage control during catheterization in patients with degraded EGL.

There are serious friction damage problems that few studies have focused on when conveying endoscope to the lesion locations. In this paper, the friction behavior between endoscope and esophageal mucosa tissue which stretched in different directions was studied by using a UMT-II Micro-Tribometer. Results show that the friction coefficient and energy dissipation decreased with the increasing circumferential strain, and enhanced with the increasing axial strain. The difference in friction behaviors was related to the structural and mechanical anisotropy of the esophageal tissue. The tearing degree on the mucosal surface gradually increased with the increasing normal force. Lidocaine could effectively reduce the friction dissipation and damage. The results can provide the basic data for safety operation and damage control during endoscopy.

In the process of surgical suturing, friction phenomena at the interface between sutures and tissues can seriously affect the suturing efficiency. However, few studies have assessed the detailed effects of types of sutures or tissues and stitching parameters on the friction behavior. In this paper, the different factors affecting the friction behaviors between sutures and tissues were studied. The unidirectional sliding wear mode in a line-on-flat configuration was selected to simulate the real surgical suturing by using a UMT-II Micro-Tribometer. Artificial skin, porcine muscle and porcine liver were used as experimental samples. Three different surface morphology and structure sutures: multifilament suture (silk), monofilament suture (prolene) and multifilament suture with coating (vicryl), were investigated in this study. The normal load was from 0.1 to 0.5 N, and the unidirectional sliding (suturing) speed was from 5 to 25 mm/s to simulate the suturing operation. Results showed that the friction coefficient at the suture–tissue interface decreased with the increase in normal load and increased with the increase in suturing speed due to the nonlinear viscoelasticity and deformation hysteresis of the soft tissues. The sutures with monofilament structure or coating could effectively reduce the friction coefficient of the suture–tissue interface. Compared to the artificial skin, the porcine tissues had the lower friction coefficients because of 30% blood and 17% interstitial fluid filled in liver and muscle, respectively, which acted as lubricants and reduced the adhesion friction coefficient of the suture–tissue interface. The results can provide guidance for the surgical suture manufacture and the surgical manipulation skills.