Organized assembly of chitosan into mechanically strong bio-composite by introducing a recombinant insect structural protein OfCPH-1.

Chitosan, known for its appealing biological properties in packaging and biomedical applications, faces challenges in achieving a well-organized crystalline structure for mechanical excellence under mild conditions. Herein, we propose a facile and mild bioengineering approach to induce organized assembly of amorphous chitosan into mechanically strong bio-composite via incorporating a genetically engineered insect structural protein, the cuticular protein hypothetical-1 from the Ostrinia furnacalis (OfCPH-1). OfCPH-1 exhibits high binding affinity to chitosan via hydrogen-bonding interactions. Simply mixing a small proportion (0.5 w/w%) of bioengineered OfCPH-1 protein with acidic chitosan precursor induces the amorphous chitosan chains to form fibrous networks with hydrated chitosan crystals, accompanied with a solution-to-gel transition. We deduce that the water shell destruction driven by strong protein-chitosan interactions, triggers the formation of well-organized crystalline chitosan, which therefore offers the chitosan with significantly enhanced swelling resistance, and strength and modulus that outperforms that of most reported chitosan-based materials as well as petroleum-based plastics. Moreover, the composite exhibits a stretch-strengthening behavior similar to the training living muscles on cyclic load. Our work provides a route for harnessing the OfCPH-1-chitosan interaction in order to form a high-performance, sustainably sourced bio-composite.

Monosodium Urate Crystal-Induced Pyroptotic Cell Death in Neutrophil and Macrophage Facilitates the Pathological Progress of Gout.

Monosodium urate (MSU) crystal deposition in joints can lead to the infiltration of neutrophils and macrophages, and their activation plays a critical role in the pathological progress of gout. However, the role of MSU crystal physicochemical properties in inducing cell death in neutrophil and macrophage is still unclear. In this study, MSU crystals of different sizes are synthesized to explore the role of pyroptosis in gout. It is demonstrated that MSU crystals induce size-dependent pyroptotic cell death in bone marrow-derived neutrophils (BMNs) and bone marrow-derived macrophages (BMDMs) by triggering NLRP3 inflammasome-dependent caspase-1 activation and subsequent formation of N-GSDMD. Furthermore, it is demonstrated that the size of MSU crystal also determines the formation of neutrophil extracellular traps (NETs) and aggregated neutrophil extracellular traps (aggNETs), which are promoted by the addition of interleukin-1ß (IL-1ß). Based on these mechanistic understandings, it is shown that N-GSDMD oligomerization inhibitor, dimethyl fumarate (DMF), inhibits MSU crystal-induced pyroptosis in BMNs and J774A.1 cells, and it further alleviates the acute inflammatory response in MSU crystals-induced gout mice model. This study elucidates that MSU crystal-induced pyroptosis in neutrophil and macrophage is critical for the pathological progress of gout, and provides a new therapeutic approach for the treatment of gout.

Clinical application value of Ultrafast Pulse Wave Velocity in early cardiovascular injury of Immunoglobulin A nephropathy.

AIM: To investigate the application and the related influencing factors of ultrafast pulse wave velocity (ufPWV) in the evaluation of carotid artery elasticity in patients with Immunoglobulin A nephropathy (IgAN). MATERIAL AND METHODS: A total of 156 IgAN patients and 50 healthy individuals were selected as the control group. The ufPWV technique was employed to measure carotid arterial elasticity parameters, including carotid intima-media thickness (cIMT), pulse wave velocity at the beginning of systole (BS-PWV) and pulse wave velocity at the end of systole (ES-PWV). RESULTS: Across the three groups (control group, IgAN patients with normal renal function, and IgAN patients with renal dysfunction) there was an increasing trend observed in cIMT, BS-PWV, and ES-PWV. Additionally, ES-PWV exhibited higher sensitivity than BS-PWV. Correlation analysis revealed that BS-PWV and ES-PWV were positively correlated with age, body mass index (BMI), systolic blood pressure (SBP), high-sensitivity C-reactive protein (hs-CRP), creatinine (Cr), blood urea nitrogen (BUN), and uric acid (UA) and negatively correlated with estimated glomerular filtration rate (eGFR). CONCLUSION: The ufPWV technique allows for the rapid and direct measurement of arterial elasticity parameters in the neck and represents a novel approach for the early diagnosis and quantitative assessment of arterial stiffness risk in IgAN patients.

Highly efficient dissolution and reinforcement mechanism of robust and transparent cellulose films for smart packaging.

The packaging of fresh foods increasingly focuses on renewable and eco-friendly cellulose films, but their low dissolution efficiency and weak mechanical strength greatly limit their wide application, which also cannot be used for smart packaging. Here, a highly efficient synergistic chloride-salt dissolution method was proposed to fabricate robust, transparent, and smart cellulose films. Cellulose films with appropriate Ca2+ concentration exhibited robust mechanical strength, better thermal stability, high transparency and crystallinity. The metal chelation of Ca2+ with cellulose chains could induce cellulose chain arrangement during the cellulose regeneration process. Particularly, compared to pure cellulose films, the tensile strength and elongation at break of cellulose films with suitable Ca2+ were increased by 167 % and 200 %, respectively. Moreover, optimal cellulose films can be used to reflect the quality of the fruit by detecting changes in ethanol gas. Hence, a novel strategy is presented to fabricate robust and transparent cellulose films with great potential application for smart packaging.

[Value of contrast-enhanced percutaneous ultrasound in the diagnosis of rotator cuff tear subtype].

OBJECTIVE: To explore characteristics of contrast-enhanced ultrasound (CEUS) images features and diagnostic value of rotator cuff tear subtypes. METHODS: From January 2019 to March 2022, percutaneous ultrasound-guided subacromial bursography (PUSB) with persutaneous ultrasound-guide tendon lesionography (PUTL) was performed on 114 patients with suspected rotator cuff injury were evaluated, including 54 males and 60 females ranged in age from 35 to 75 years old with an average of (58.8±8.7 ) years old;76 patients on the right side and 38 patients on the left side;the course of disease ranged from 0.13 to 111 months with an average of (10.2±9.8) months. GE LOGIQ E9 color doppler ultrasound diagnostic high frequency(6 to 12 MHz) was used to CEUS Using arthroscopy as gold standard, receiver operating characteristic (ROC) curve was used to evaluate diagnostic efficacy of US, MRI and CEUS for rotator cuff injury, also sensitivity, specificity, positive predictive value, negative predictive value and accuracy were calculated. RESULTS: The sensitivity of US in diagnosing full-thickness tears was 72.1%, specificity was 93.0%, and accuracy was 85.1%. The sensitivity, specificity and accuracy of MRI diagnosis of full-thickness tear were 90.9%, 92.6% and 92.1% respectively. The sensitivity, specificity and accuracy of CEUS in diagnosis of full-thickness tear were 100%. The sensitivity, specificity and accuracy of US in the diagnosis of partial tear were 85.7%, 77.2% and 79.8% respectively. The sensitivity, specificity and accuracy of MRI diagnosis of partial tear were 83.7%, 81.7% and 82.5% respectively. The sensitivity, specificity and accuracy of CEUS in diagnosis of partial tear were 95.7%, 92.6% and 93.9% respectively. There were significant differences in diagnosis results of US, MRI and CEUS for rotator cuff bursa tear (P<0.001). Kapp test showed good consistency between CEUS and arthroscopy in diagnosing rotator cuff tear subtypes (full-thickness and partial tears). CONCLUSION: Using PUSB/PUTL to observe distribution of contrast media in bursa, tendon and joint cavity to evaluate the type of rotator cuff tear, its diagnostic performance is significantly better than US and MRI. Therefore, percutaneous contrast-enhanced ultrasound can be a reliable method for diagnosing subtypes of rotator cuff tears.

Study of Finite Element Simulation on the Mechano-Bactericidal Mechanism of Hierarchical Nanostructure Arrays.

Biomimetic nanostructures with bactericidal performance have become the research focus in constructing sterilization surfaces, but the mechano-bactericidal mechanism is still not fully understood, especially for the hierarchical nanostructure arrays with different heights. Herein, the interaction between Escherichia coli cells and nanostructure arrays was simulated by finite element, and the initial rupture points, i.e., critical action sites, of bacterial cells and the effects of nanostructure geometries on the cell rupture speed were analyzed based on the mechano-response of Escherichia coli cells on flat (identical heights) and hierarchical nanostructure arrays. The critical action sites of bacterial cells on nanostructure arrays are all at the three-phase junction zone of cell-liquid-nanostructure, but they are slightly shifted by the height difference ΔH of nanostructures on hierarchical nanopillar (NP)/nanosheet (NS) arrays, where the NP is higher than the NS. When ΔH < 20 nm, the site nears the NS corners, and when ΔH ≥ 20 nm, the site is consistent with that of the NP/NP array, i.e., the site locates at the three-phase junction zone of cell-liquid-high NP. In addition, except for decreasing the NP diameter, the NS thickness/width, or properly increasing the nanostructure spacing, the cell rupture can be accelerated via increasing the ΔH of nanostructures. ΔH = 40 nm is distinguished as the boundary for the effect of nanostructure ΔH on the cell rupture speed. When ΔH < 40 nm, the cell rupture speed rapidly increases as the ΔH increases; when ΔH ≥ 40 nm, the cell rupture speed reaches the maximum value and remains stable. This study provides a new strategy on how to design high-efficiency bactericidal surfaces.

All-naturally structured tough, ultrathin, and washable dual-use composite for fruits preservation with high biosafety evaluation.

This work develops a sustainable and global strategy to enhance fruit preservation efficacy. The dual-use composite coating or film comprises silk fibroin/cellulose nanocrystals (SF/CNC) with superior ductility through a synergistic plasticizing effect of glycerol and natural aloe-emodin powder (AE) as antimicrobial agents. To confirm our strategy, two common fruit preservation materials (edible surface coating-SCA-CS; packaging film-SCA-PF) and five different fruits (strawberries, bananas, apples, blueberries, and guavas) have been used. Moreover, SCA-CS coating with antibacterial and antioxidant activities formed an ultrathin layer on the fruit's surfaces with a thickness of 7.7 µm and could be easily washable. Therefore, bananas and strawberries' shelf-life with SCA-CS coating can be extended for 9 days and 6 days, respectively. The discharge water of SCA-CS has excellent biosafety in an indoor environment with no threat to plant health (microgreens bean sprouts germination as a case study). The plant exhibited positive results within 15 days, and leaves maintained their green color with a germination rate of 97.6 %. The toughness of SCA-PF film increased by 14,685.7 % with a water vapor transmission rate (WPTR) of 17 g mm m-2 day-1, which confirms that the concept of SCA-PF film and SCA-CS coating are feasible to be used for fruit preservation/packaging.

The Value of Percutaneous Ultrasound-Guided Subacromial Bursography for Rotator Cuff Tear in Elderly Patients with Shoulder Pain.

Objective: Based on the analysis of the images of acromial slide, we explored the application of percutaneous ultrasound-guided subacromial bursography (PUSB) on rotator cuff tear (RCT) in diagnosing elderly patients with shoulder pain. Methods: Eighty-five patients who were clinically diagnosed with RCT and underwent PUSB examination in the department of ultrasound in our hospital were enrolled as the subjects. Independent samples t-test was used to analyze the general characteristics. Based on the gold standard of shoulder arthroscopy, the diagnostic efficacy of ultrasound, magnetic resonance imaging (MRI), and PUSB was evaluated. The sensitivity, specificity, positive and negative predictive values, and accuracy were calculated as well. The consistency of these techniques with shoulder arthroscopy in diagnosing the RCT stage was additionally compared using Kappa test. Results: In patients with large full-thickness RCT, the 100% detection rate was achieved by the techniques of ultrasound, MRI, and PUSB. For patients with small full-thickness RCT, the detection rate of PUSB (100%) was evidently higher than those of ultrasound and MRI. Similar results were shown in the detection rates of patients with bursal-side partial-thickness RCT (90.5%) and articular-side partial-thickness RCT (86.9%). More importantly, the sensitivity, specificity, and accuracy of PUSB in patients with both full-thickness RCT and partial-thickness RCT were significantly better than those of ultrasound and MRI. Conclusion: PUSB has a better efficacy in the detection of RCT than ultrasound and MRI, showing its feasibility as an important imaging method to evaluate the degree of RCT.

Thermo-sensitive composite microspheres incorporating cellulose nanocrystals for regulated drug release kinetics.

Thermo-sensitive composite microspheres (TPCP) were developed to achieve the on-demand release of drugs. The TPCP microspheres were synthesized using Oil-in-Water (O/W) emulsion evaporation technique and then impregnated with thermo-sensitive polyethylene glycol (PEG). The addition of cellulose nanocrystals (CNCs) significantly enhance thermal stability, crystallization ability, and surface hydrophilicity of TPCP microspheres due to heterogeneous nucleation effect and hydrogen bonding interaction, resulting in stable microsphere structure. The thermal degradation temperature (Tmax) increased by 13.8 °C, and the crystallinity improved by 20.9 % for 10 % TPCP. The thermo-sensitive composite microspheres showed the regulated cumulative release according to in vitro human physiological temperature changes. Besides, four release kinetics and possible release mechanism of TPCP microspheres were provided. Such thermo-responsive composite microspheres with control microsphere sizes and high encapsulation rate may have the potential to the development of on-demand and advanced controlled-release delivery systems.

Monosodium urate crystals with controlled shape and aspect ratio for elucidating the pathological progress of acute gout.

Gout is a self-limiting inflammatory arthritis mediated by the precipitation of monosodium urate (MSU) crystals that further activate the NLRP3 inflammasome and initiate a cascade of inflammatory events. However, the key physicochemical properties of MSU crystals that determine the acute phase of gout have not been fully identified. In this study, a library of engineered MSU crystals with well-controlled size and shape is designed to explore their proinflammatory potentials in mediating the pathological progress of gout. It is demonstrated that medium-sized long aspect ratio MSU crystals induce more prominent IL-1ß production in vitro due to enhanced cellular uptake and the production of mitochondrial reactive oxygen species (mtROS). The characteristics of MSU crystals are also correlated with their inflammatory potentials in both acute peritonitis and arthritis models. Furthermore, 2-hydroxypropyl-ß-cyclodextrin (HP-ß-CD) is demonstrated to inhibit MSU-induced oxidative burst by removing plasma membrane cholesterol. As a result, it attenuates the inflammatory responses both in vitro and in vivo. Additionally, antioxidant N-acetylcysteine (NAC) is shown to alleviate acute gouty symptom by suppressing oxidative stress. This study identifies the key physicochemical properties of MSU crystals that mediate the pathogenesis of gout, which sheds light on novel design strategies for the intervention of gout.

Traditional Uses, Phytochemistry, Pharmacology and Toxicology of Rhizoma phragmitis: A Narrative Review.

Rhizoma phragmitis is a common Chinese herbal medicine whose effects are defined as 'clearing heat and fire, promoting fluid production to quench thirst, eliminating irritability, stopping vomiting, and disinhibiting urine'. During the Novel Coronavirus epidemic in 2020, the Weijing Decoction and Wuye Lugen Decoction, with Rhizoma phragmitis as the main herbal component, were included in The Pneumonia Treatment Protocol for Novel Coronavirus Infection (Trial Version 5) due to remarkable antiviral effects. Modern pharmacological studies have shown that Rhizoma phragmitis has antiviral, antioxidative, anti-inflammatory, analgesic, and hypoglycemic functions, lowers blood lipids and protects the liver and kidney. This review aims to provide a systematic summary of the botany, traditional applications, phytochemistry, pharmacology and toxicology of Rhizoma phragmitis.

Resilience, coping style, and COVID-19 stress: effects on the quality of life in frontline health care workers.

The aims of the study were to assess the contribution of resilience, coping style, and COVID-19 stress on the quality of life (QOL) in frontline health care workers (HCWs). The study was a cross-sectional surveyperformed among 309 HCWs in a tertiaryhospital during the outbreak of COVID-19 in China. Data were collected through an anonymous, self-rated questionnaire, including demographic data, a 10-item COVID-19 stress questionnaire, Generic QOL Inventory-74, Connor-Davidson Resilience Scale, and the Simplified Coping Style Questionnaire. Hierarchical regression was used to analyse the relationship between the study variables and the QOL. Among the 309 participants, resilience and active coping were positively correlated with the QOL (P<0.001), whereas, working in confirmed case wards, COVID-19 stress, and passive coping were negatively correlated with the QOL (P<0.001). Resilience and the active coping were negatively correlated with COVID-19 stress (P<0.001). Resilience, coping style,and COVID-19 stressaccounted for 32%, 13%, and 8% of the variance in predicting the Global QOL, respectively. In conclusion, working in confirmed COVID-19 case wards and COVID-19 stress impaired the QOL in HCWs. Psychological intervention to improve the resilience and coping style, and reduce COVID-19 stress are important in improving the QOL and mental health of HCWs.

Validation of the mechano-bactericidal mechanism of nanostructured surfaces with finite element simulation.

The mechano-bactericidal property of nanostructured surfaces has become the focus of intensive research toward the development of a new generation of antibacterial surfaces, especially in the current era of spreading antibiotic resistance. However, the mechanisms underlying nanostructured surfaces mechanically damaging bacteria remain unclear, which ultimately limits translational potential toward real-world applications. Using finite element simulation technique, we developed the three-dimensional thin wall with turgor pressure finite element model (3D-TWTP-FEM) of bacterial cell and verified the reliability of this model by the AFM indentation experiment simulation of the cell, and the cell model is able to simulate suspended bacterial cell and the process of cell adhering to the flat and nanopillar surfaces. Since bacterial cells suffer greater stress and deformation on the nanopillar surfaces, a two-stage model of the elastic and creep deformation stage of the cells on the nanostructured surfaces was developed. The calculations show that the location of the maximum stress/strain on the cells adhered to the nanopillar surfaces is at the liquid-cell-nanopillar three phase contact line. The computational results confirmed the ability of nanostructured surfaces to mechanically lyse bacteria and gave the effect of nanopillar geometry on the efficiency and speed of bacterial cell rupture. This study provides fundamental physical insights into how nanopillar surfaces can serve as effective and fast mechanical antimicrobial materials.

Low-Temperature Hydrothermal Synthesis of Novel 3D Hybrid Nanostructures on Titanium Surface with Mechano-bactericidal Performance.

Titanium is extensively employed in modern medicines as orthopedic and dental implants, but implant failures frequently occur because of bacterial infections. Herein, three types of 3D nanostructured titanium surfaces with nanowire clusters (NWC), nanowire/sheet clusters (NW/SC) and nanosheet clusters (NSC), were fabricated using the low-temperature hydrothermal synthesis under normal pressure, and assessed for the sterilization against two common human pathogens. The results show that the NWC and NSC surfaces merely display good bactericidal activity against Escherichia coli, whereas the NW/SC surface represents optimal bactericidal efficiency against both Escherichia coli (98.6 ± 1.23%) and Staphylococcus aureus (69.82 ± 2.79%). That is attributed to the hybrid geometric nanostructure of NW/SC, i.e., the pyramidal structures of ∼23 nm in tip diameter formed with tall clustered wires, and the sharper sheets of ∼8 nm in thickness in-between these nanopyramids. This nanostructure displays a unique mechano-bactericidal performance via the synergistic effect of capturing the bacteria cells and penetrating the cell membrane. This study proves that the low-temperature hydrothermal synthesized hybrid mechano-bactericidal titanium surfaces provide a promising solution for the construction of bactericidal biomedical implants.

Anxiety and depression in frontline health care workers during the outbreak of Covid-19.

BACKGROUND: The pandemic of coronavirus disease (Covid-19) seriously impacts the health and well-being of all of us. AIMS: We aim to assess the psychological impact of Covid-19 on frontline health care workers (HCWs), including anxiety, depression and stress of threat of the disease. METHOD: The study was a cross-sectional survey among the frontline HCWs in a hospital at Jinan, China. Data were collected through an anonymous, self-rated questionnaire, including basic demographic data, a 10-item Covid-19 stress questionnaire, the Self-Rating Anxiety Scale (SAS) and the Self-Rating Depression Scale (SDS). The risk and rate of anxiety, depression and stress of Covid-19 were estimated. RESULTS: Among the 309 participants, there were 88 (28.5%) with anxiety and 172 (56.0%) with depression. Multivariate logistic regression analyses showed that age ⩽ 30 years, age > 30 to 45 years, working in confirmed case isolation wards, and worrying about disinfection measures being not sufficient were independently associated with anxiety with an odds ratio (95% confidence interval, CI) of 4.4 (1.6-12.2), 3.1 (1.1-8.8), 2.3 (1.4-4.0) and 2.5 (1.5-4.3), respectively; age ⩽ 30 years, age > 30 to 45 years, nurse and worrying about disinfection measure being not sufficient were independently associated with depression with an odds ratio (95% CI) of 3.8 (1.8-7.8), 2.7 (1.3-5.7), 2.5 (1.1-5.6) and 2.1 (1.3-3.5), respectively. CONCLUSIONS: A high prevalence of anxiety and depression was found among frontline HCWs during the COVID-19 outbreak. More psychological care should be given to young staffs and nurses. Measures to prevent professional exposure is important for HCWs' physical and mental health.

Preparation of carbon/Al2O3/nZVI magnetic nanophase materials produced from drinking water sludge for the removal of As(V) from aqueous solutions.

Drinking water sludge (DWS) contains organic carbon and metal ions with the potential to prepare adsorbents. In this research, DWS was separated into two parts by acid leaching, i.e., an acid leaching carbonization sludge (ALCS) and an acid leaching solution. Iron and aluminum were extracted from the acid leaching solution and loaded onto ALCS by sedimentation and liquid-phase reduction to prepare a carbon/Al2O3/nZVI magnetic adsorption material (ALCS-Al-Fe). The optimum arsenic removal conditions, adsorption kinetics, and isotherm were determined, and the characteristics of the adsorbent ALCS-Al-Fe were investigated. The results showed that the composite exerted a favorable arsenic removal effect due to the electrostatic adsorption of nanometer zero-valent iron as well as ion exchange and complexation between the OH- groups on the surface of ALCS-Al-Fe and As(V). The pH change had a slight effect on the adsorption capacity, while the common anions SO42- and SiO32- showed obvious inhibitory effects. Considering that alkalinity is beneficial to arsenic ion desorption, NaOH was used in desorbing to conduct 6 cycles of regeneration experiments, and the final removal rate could still reach 90.5%. Therefore, the concept of green development of preparing magnetic adsorbents by using whole component of DWS is significant to the exploitation of sludge recycling.

Poly-ion complex (PIC) formation of heparin and polyamines: PIC with tetrakis (3-aminopropyl) ammonium allows sustained release of heparin.

Physical mixtures of cationic polymers and heparin have been developed to overcome the limitations of unfractionated heparin. In this study, we found that heparin associates with natural polyamines in water, resulting in the generation of a poly-ion complex (PIC). PIC formation (or stability) was influenced by the concentration and ratio of heparin and polyamines, molecular weight of heparin, nature of polyamines, and pH conditions. Interestingly, the PIC obtained when heparin and tetrakis (3-aminopropyl) ammonium (Taa) were mixed exhibited stability and was sticky in nature. PIC formation was due to an electrostatic interaction between heparin and Taa. Heparin-Taa PIC was administered subcutaneously to mice, and the time to maximum heparin concentration within the therapeutic range of heparin was markedly increased compared to that after a single dose of heparin. These results suggest that the quaternary ammonium structure of Taa is critical for the preparation of a stable PIC, thereby allowing the sustained release of heparin into the blood.

Surface Modification of Stöber Silica Nanoparticles with Controlled Moiety Densities Determines Their Cytotoxicity Profiles in Macrophages.

Physicochemical properties of nanomaterials play important roles in determining their toxicological profiles during nano-biointeraction. Among them, surface modification is one of the most effective manners to tune the cytotoxicity induced by nanomaterials. However, currently, there is no consistency in surface modification including moiety types and quantities considering the conflicting toxicological profiles of particles across different studies. In this study, in order to systematically investigate how the moiety density affects cytotoxicity of NPs, we chose three different types of functional groups, that is, -NH2, -COOH, and -PEG, and further controlled their densities on modified Stöber silica nanoparticles (NPs). We demonstrated that densities of functional groups could significantly affect the cytotoxicities of Stöber silica NPs. Regardless of the types of functional groups, high grafting densities could ameliorate the cytotoxicities induced by Stöber silica NPs in macrophages, for example, J774A.1 and N9 cells. When equal amounts of functional groups were present, the cell viability increased in the order of -COOH < -NH2 < -PEG. Furthermore, it was shown that surface modification could significantly affect the quantities of the surface silanol, which is the determining factor that affects their cytotoxicity. These results show that it is critical to control the surface moiety both quantitatively and qualitatively, which can tune the interaction outcomes at the nano-bio interface. The results found in this article provide useful guidance to adjust nanomaterial cytotoxicity for safer biomedical applications.

Mechanism Study of Bacteria Killed on Nanostructures.

It is important to study the bactericidal mechanism with nanostructures for the design and preparation of high-efficiency sterilization materials. In this paper, the interfacial energy gradient between cells and nanopillars is proposed to be the driving force to promote cells to migrate into nanostructures and get killed. The expressions of interfacial energy and its gradient were first established, then the deformation of cells pressured by nanostructures was calculated. The results show that the interfacial energy gradient or the pressure on cells is influenced by nanopillar parameters substantially. The smaller the nanopillar diameter and the larger the pitch, the greater the pressure on cells. Only high enough nanocolumns can ensure sufficient cell creep deformation and become punctured. Furthermore, a cell volume and its adhesion morphology also influence the interaction between cells and nanostructures. The smaller the cell volume, the greater the pressure on it. And the larger the contact angle of adhered cells, the greater the pressure on the cells by nanopillars. Besides, the wettability of substrate material also influences the interaction between cells and nanopillars. It can be concluded that the model is reasonable and reliable since its calculation results are in good accordance with the experimental measurements.