MoOxNWs with mechanical damage - oriented synergistic photothermal / photodynamic therapy for highly effective treating wound infections

Reactive oxygen species (ROS)-based therapy has emerged as a promising antibacterial strategy. However, it faces the limitations of uncontrollable space-time release and excessive lipid peroxidation, which may lead to a series of metabolic disorders and decreased immune function. In this study, mechanical damage by molybdenum oxide nanowires (MoOxNWs) is introduced as a synergistic factor to enhance the photothermal and photodynamic effects for controllable and efficient antibacterial therapy. Through their sharp ends, the nanowires can effectively pierce and damage the bacterial cells, thus facilitating the entry of externally generated ROS into the cells. The ROS are generated via photodynamic effect of the nanowires under a mere 5 min of near-infrared light irradiation. This approach enhances the photothermal (by 27.3 %) and photodynamic properties of ROS generation. MoOxNWs (100 μg·mL-1) achieve sterilisation rates of 97.67 % for extended-spectrum β-lactamase-producing E. coli and 96.34 % for methicillin-resistant Staphylococcus aureus, which are comparable or even exceeding the efficacy of most MoOx-based antibacterial agents. Moreover, they exhibit good biocompatibility and low in vivo toxicity.

Indirect treatment of plasma-processed air to decrease decay and microbiota of strawberry fruit caused by mechanical damage

Due to the soft texture of strawberry fruit, it is highly susceptible to mechanical damage during postharvest supply chains, resulting in decay and quality deterioration. Urgent investigation is needed on the treatment techniques to mitigate the impact of postharvest mechanical damage of strawberry fruit. In the present study, the effect of indirect plasma-processed air (PPA) pretreatment to decrease decay and microbiota of strawberry fruit caused by mechanical damage was investigated. The results show PPA pretreatment reduced the total counts of indigenous microbiota on the surface of intact and mechanical damaged strawberry fruit by 4.29 and 3.76 log₁₀CFU/g at day 0, respectively, and reduced the counts of S. aureus and E. coli inoculated on strawberry fruit by 3.05-3.16 and 3.55-3.56 log₁₀CFU/g, respectively. The disease incidence of fruit inoculated with Botrytis cinerea was also decreased by 6.67 %-18.89 % during storage. Besides, PPA pretreatment reduced the decay rate of strawberry fruit by 5.56 %-21.11 % during storage and did not significantly affect the firmness, color index of red grapes (CIRG) and total soluble solids (TSS) content of strawberry fruit. DHHP results indicate that the antioxidant activity of the strawberry fruit was increased. After PPA pretreatment, 39 metabolites were differentially accumulated in strawberry fruits, 37 of which were up-regulated, including flavonoids, phenolic acids and organic acid.

Sunlight propelled two-dimensional nanorobots with enhanced mechanical damage of bacterial membrane

Bacterial pollution in water sources poses a serious threat to human health and causes a water crisis. To treat it efficiently and ecologically, many studies have explored the antibacterial properties of two-dimensional nanomaterials in water, but their static antibacterial modes limit their effectiveness. In this work, we designed a facile and effective antibacterial nanorobots by loading super small gold nanorods (sAuNR) onto the surface of MXene nanosheets (MXene@sAuNR). The plasmon resonance effect of sAuNR can enhance the optical absorption cross section of the nanorobots, thereby improving their motion ability under irradiation and then causing cell membrane mechanical damage to bacteria. Our research proved that nanorobots with good optical driving characteristics displayed gratifying antibacterial properties even at ultra-low concentration as 5 µg/mL within 30 min. Furthermore, the nanorobots showed satisfactory antibacterial efficiency in real river samples under sunlight irradiation. These nanorobots presented in this study provides valuable insights towards designing self-energy collection and self-driving antibacterial materials that overcome the shortcomings of conventional static antibacterial methods. As sunlight is the cheapest and natural light source, these nanorobots have opened an effective and sustainable way for large-scale treatment of bacterial pollution in water.

Impact on polyphenols recovery

The influence of ultrasound treatment (US) on cellular damage of olive leaf tissue was studied. Mechanical damage and thermal effect of US were characterized. The level of tissue damage was defined by the diffusivity disintegration index Z_D based on the diffusivity of solutes extracted from olive leaves differently treated. The Arrhenius form using the temperature dependences of the thermal treatment time within the temperature interval 20-90 °C was observed for the thermal process. The corresponding activation energy ΔUT was estimated as 57 kJ/mol. The temperature dependences of electrical conductivity were measured for extracts of intact and maximally treated olive leaves. Then the diffusivity disintegration index Z_D and total phenolic compounds recovery for three studied US powers were calculated (100, 200, and 400 W). The results evidenced that the mechanically stimulated damage in olive leaf tissue can occur even at a low US power of 100 W if treatment time is long enough (t = 3.5 h). The US treatment noticeably accelerated the diffusion process mechanically in addition to its thermal effect. Trials in aqueous solution revealed the dependence of polyphenols extraction on damage level with respect to the US power applied.

A source-sink model explains the difference in the metabolic mechanism of mechanical damage to young and senescing leaves in Catharanthus roseus

BACKGROUND

Mechanical damage is an unavoidable threat to the growth and survival of plants. Although a wound to senescing (lower) leaves improves plant vitality, a wound to younger (upper) leaves often causes damage to or death of the whole plant. Source-sink models are often used to explain how plants respond to biotic or abiotic stresses. In this study, a source-sink model was used to explain the difference in the metabolic mechanism of mechanical damage to young and senescing leaves of Catharanthus roseus.

RESULTS

In our study, GC-MS and LC-QTOF-MS metabolomics techniques were used to explore the differences in source-sink allocation and metabolic regulation in different organs of Catharanthus roseus after mechanical damage to the upper/lower leaves (WUL/WLL). Compared with that of the control group, the energy supplies of the WUL and WLL groups were increased and delivered to the secondary metabolic pathway through the TCA cycle. The two treatment groups adopted different secondary metabolic response strategies. The WLL group increased the input to the defense response after damage by increasing the accumulation of phenolics. A source-sink model was applied to the defensive responses to local (damaged leaves) and systemic (whole plant) damage. In the WUL group, the number of sinks increased due to damage to young leaves, and the tolerance response was emphasized.

CONCLUSION

The accumulation of primary and secondary metabolites was significantly different between the two mechanical damage treatments. Catharanthus roseus uses different trade-offs between tolerance (repair) and defense to respond to mechanical damage. Repairing damage and chemical defenses are thought to be more energetically expensive than growth development, confirming the trade-offs and allocation of resources seen in this source-sink model.

Effect of peroxyacetic acid treatment and bruising on the bacterial community and shelf-life of baby spinach

The importance of leaf integrity, i.e. the effects of bruising (mechanical damage), and sanitisation with peroxyacetic acid (PAA) on bacterial communities of ready-to-eat baby spinach remains unclear. Two shelf-life studies were conducted at 4 °C to investigate the effect of bruising and sanitisation on the growth of spoilage microorganisms. In the first experiment, both bruising treatments (100% and 40% of leaves) halved shelf life to 12 d, whereas intact leaves had a shelf-life of 23 d. Bruising had no influence on bacterial diversity during shelf-life, though some differences in the relative abundance of minor genera were observed. Pseudomonas and Pantoea were the most dominant bacterial genera, regardless of bruising treatment. High throughput amplicon sequencing also identified other spoilage bacteria including Chryseobacterium, Stenotrophomonas, Bacillus, Sphingobacterium, Erwinia and Flavobacterium. In the second experiment, washing of intact baby spinach with a sanitiser (80 mg/L: PAA) reduced microbial load as determined by aerobic plate count but did not immediately affect the presence/relative abundance of most of the genera of spoilage bacteria observed. During shelf-life, the bacterial diversity of sanitised leaves was significantly lower than on water-washed leaves. Although sanitisation resulted in a higher initial log reduction in microbial load compared to control (portable tap water), sanitisation did not extend the shelf life of baby spinach (23 d). Sanitised spinach had reduced bacterial diversity however, by the end of shelf life, both sanitised and water-washed spinach was dominated by Pseudomonas and Pantoea spoilage bacteria. This study demonstrated for the first time that the shorter shelf life of bruised leaves was related to faster microbial growth rather than changes in bacterial diversity or community composition.

Repair of a severe palm injury with anterolateral thigh and ilioinguinal flaps: A case report

BACKGROUND

In daily life and work, there are more and more patients with trauma to the hand, which often results in skin and soft tissue defects. Although there are many repair methods, the function and appearance of the fingers will be adversely affected if the repair is inadequate.

CASE SUMMARY

In the present report we describe an 18-year-old male patient whose right hand was mangled by a machine. X-ray imaging showed that a right hand bone (middle finger) was absent and the alignment was poor. After hospitalization, he was diagnosed with a severe right hand injury, skin and soft tissue defects, partial finger defects, and a skin degloving injury. He underwent reconstructive surgery with anterolateral thigh and ilioinguinal flaps. After two repair operations, satisfactory results were obtained, including good fracture healing, good skin flap shape, and good wrist joint function.

CONCLUSION

This case highlights the good effect of anterolateral thigh and ilioinguinal flaps repair technique on severe palm injury.

Damage sensitivity of dental zirconias to simulated occlusal contact

OBJECTIVE

Mechanical damages can occur from dental restoration processing and fitting, or while it is in-service. This study evaluates the damage sensitivity of translucent zirconia (5Y-PSZ) relative to conventional 3Y-PSZ following mouth-motion simulations at various loads.

METHODS

5Y-PSZ and 3Y-PSZ discs were adhesively bonded to a dentin-like substrate and divided into groups according to the load (50 N or 200 N) and number of cycles (up to 10⁶) used in the chewing simulation. Specimens were mounted with 30° inclination in an electrodynamic mouth-motion simulator, and subjected to contact-slide-liftoff cyclic loading in water. Surface and sub-surface damages were analyzed using a sectioning technique. After the simulation, specimens were removed from the substrate and loaded with the damaged surface in tension for biaxial strength testing to assess their damage tolerance.

RESULTS

The strength of both ceramics underwent significant degradation after mouth-motion simulations. For 5Y-PSZ, the strength degradation was greater (∼60%) and occurred at a lower number of cycles than 3Y-PSZ. Herringbone cracks emerged on 3Y-PSZ and 5Y-PSZ surfaces under a 200-N load after 50 and 10 cycles, respectively. Meanwhile at a 50-N load, cracks formed at ∼1000 cycles in both ceramics. Further increasing the number of cycles only had moderate effects on the strength of both ceramics, despite an increase in surface and sub-surface damage. More significantly, a 50-N occlusal load can debase the zirconia strengths as much as a 200-N load.

SIGNIFICANCE

Surface flaws produced during the chewing simulation are capable of significant strength degradation in zirconia, even after a small number of low-load cycles.

Packaging design proposal motivated by the identification of damages in Andean blackberry (Rubus glaucus Benth)

Andean blackberry is a fruit recognized by its health benefits associated with its high content of bioactive compounds. However, it is also one of the most perishable fruits because it does not have a protective cuticle, and it shows high respiration and ethylene production rates. Furthermore, it is susceptible to microbiological attacks. During harvest and commercialization, the highest percentage of losses is caused by factors such as the maturity stage, harvest practices and containers, and marketing packages. The current work aims at studying the effect of the package on fruit quality, for which the harvested fruits were placed in clamshells, traditional wooden and plastic crates with a capacity of 7 kg. The quality of the fruit was evaluated by counting in situ, damage by bruising, cuts, deformations, microbiological attacks, missing of the peduncle, and non-uniform pollination. Damage analysis included the evaluation of different regression models considering information criteria and significant parameters (P ≤ 0.05). The use of traditional packages led to higher damage from cuts and bruises. Although in clamshells there was a higher probability of finding healthy fruits, a proposal for its redesign is proposed to guarantee a better quality and shelf life of the Andean blackberry fruits.

A mechanical approach to understanding the impact of the nematode Anguillicoloides crassus on the European eel swimbladder

One of the most detrimental factors in the drastic decline of the critically endangered European eel (Anguilla anguilla) was the inadvertent introduction of the invasive nematode Anguillicoloides crassus Infection primarily affects the swimbladder, a gas-filled organ that enables the eel to control its depth in the water. A reduction in swimbladder function may be fatal for eel undergoing their spawning migration to the Sargasso Sea, a journey of over 5000 km. Although the physiological damage caused by this invasive parasite is well studied through the use of quantifiable gross pathological indices, providing a good measure of the swimbladder health status, they cannot separate the role of mechanical and morphological damage. Our study examined the appropriateness of three commonly used indices as a measure of mechanical damage by performing uniaxial tensile tests on swimbladder specimens obtained from an infected eel population. When the test results were compared with the gross pathological indices it was found that thickness correlated most strongly with mechanical damage, both confirming and, more importantly, explaining the counterintuitive findings of earlier work. In a damaged swimbladder, the immune response leads to a trade-off; increasing wall thickness raises the pressure required for organ rupture but decreases strength. The results indicate that for moderate infection the mechanical integrity of the swimbladder can be maintained. For severe infection, however, a reduction in mechanical integrity may reach a tipping point, thereby affecting the successful completion of their oceanic migration.

Red blood cell tolerance to shear stress above and below the subhemolytic threshold

Mechanical circulatory support device (MCS) design has improved over the years and yet blood damage (e.g., hemolysis) remains a problem. Accumulating evidence indicates a subhemolytic threshold for red blood cells (RBC)-a threshold at which RBC deformability is impaired prior to hemolysis. The current study aimed to assess the deformability of RBC exposed to supra-physiological shear stresses that are typical of MCS devices and assess whether a method used to estimate an individualized subhemolytic threshold, accurately demarcates whether future application of shear stress was damaging. Suspensions of RBC were "conditioned" with discrete magnitudes of shear stress (5-100 Pa) for specific durations (1-16 s). Cellular deformability was subsequently measured via ektacytometry and a mechanical sensitivity (MS) index was calculated to identify the subhemolytic threshold. Thereafter, fresh RBC suspensions were exposed to a magnitude of shear stress 10 Pa above, 10 Pa below, or matched to a donor's previously estimated subhemolytic threshold for a given duration (1, 4, 16 s) to ascertain the sensitivity of the subhemolytic threshold. The MS index of RBC was significantly impaired following exposure to 10 Pa above the subhemolytic threshold (p < 0.0001), and significantly enhanced following exposure to 10 Pa below the subhemolytic threshold (p < 0.01). For all shear conditions, there was no significant increase in free hemoglobin. Functional assessments of RBC may be useful when conducting biocompatibility testing of MCS devices, to detect trauma to blood prior to overt cell rupture being induced.

Mechanical degradation of TiO2 nanotubes with and without nanoparticulate silver coating

The primary objective of this research was to evaluate the extent of mechanical degradation on TiO2 nanotubes on Ti with and without nano-particulate silver coating using two different lengths of TiO2 nanotubes-300nm and ~1µm, which were fabricated on commercially pure Titanium (cp-Ti) rods using anodization method using two different electrolytic mediums-(1) deionized (DI) water with 1% HF, and (2) ethylene glycol with 1% HF, 0.5wt% NH4F and 10% DI water. Nanotubes fabricated rods were implanted into equine cadaver bone to evaluate mechanical damage at the surface. Silver was electrochemically deposited on these nanotubes and using a release study, silver ion concentrations were measured before and after implantation, followed by surface characterization using a Field Emission Scanning Electron Microscope (FESEM). In vitro cell-material interaction study was performed using human fetal osteoblast cells (hFOB) to understand the effect of silver coating using an MTT assay for proliferation and to determine any cytotoxic effect on the cells and to study its biocompatibility. No significant damage due to implantation was observed for nanotubes up to ~1µm length under current experimental conditions. Cell-materials interaction showed no cytotoxic effects on the cells due to silver coating and anodization of samples.

Duration of emission of volatile organic compounds from mechanically damaged plant leaves

Classical biological control of invasive alien weeds depends on the use of arthropod herbivores that are sufficiently host specific to avoid risk of injuring nontarget plants. Host plant specificity is usually evaluated by using a combination of behavioral and developmental experiments under choice, no-choice and field conditions. Secondary plant compounds are likely to have an important influence on host plant specificity. However, relatively little is known about the volatile organic compounds (VOCs) that are emitted by target and nontarget plants, and how environmental conditions may affect their emission. Previous studies have shown that mechanical damage of leaves increases the composition and content of VOCs emitted. In this study we measured the VOC emissions of five species of plants in the subtribe Centaureinae (Asteraceae)--Carthamus tinctorius, Centaurea cineraria, Centaurea melitensis, Centaurea rothrockii, and Centaurea solstitialis--that have previously been used in host specificity experiments for a prospective biological control agent of yellow starthistle (C. solstitialis). Leaves of each plant were punctured with a needle and the VOCs were collected by solid-phase microextraction (SPME) periodically over 48 h and analyzed by GC-MS. A total of 49 compounds were detected. Damage caused an immediate increase of 200-600% in the composition of VOCs emitted from each plant species, and the amounts generally remained high for at least 48 h. The results indicate that a very unspecific mechanical damage can cause a prolonged change in the VOC profile of plants.

Erythrocyte deformability responses to intermittent and continuous subhemolytic shear stress

BACKGROUND

Previous studies have demonstrated that red blood cells (RBC) either lyse or at least experience mechanical damage following prolonged exposure to high shear stress (≥100 Pa). Conversely, prolonged shear stress exposure within the physiological range (5-20 Pa, 300 s) was recently reported to improve RBC deformability. This study investigated the relationships between shear stress and RBC deformability to determine the breakpoint between beneficial vs. detrimental exposure to shear stress (i.e., "subhemolytic threshold"). A second aim of the study was to determine whether the frequency of intermittent application of shear stress influenced the subhemolytic threshold.

METHODS

RBC were exposed to various levels of shear stress (0-100 Pa) in a Couette type shearing system for 300 s. RBC deformability was then immediately measured via ektacytometry. Parallel experiments were conducted at the same shear stresses, except the application time differed while keeping constant the total exposure time: shear stress was applied either for 30 s and repeated 10 times (10×30 s) or applied for 15 s and repeated 20 times (20×15 s).

RESULTS

For a range of donors, the subhemolytic threshold with constant shear stress application was between 30-40 Pa. When physiological shear stress was applied in an intermittent manner, more frequent applications tended to improve (i.e., increase) RBC deformability. However, when supra-physiological shear stress was applied, both continuous and intermittent protocols damaged RBC. Changes of RBC mechanical behavior occurred without increases of hemoglobin in the suspending media, thus attesting to the absence of hemolysis.

CONCLUSION

Shear stress has a biphasic effect on the mechanical properties of RBC, with the duration and rate of exposure appearing to have minimal impact on the subhemolytic threshold when compared with the magnitude of applied shear stress.

Mechanical bioeffects of acoustic droplet vaporization in vessel-mimicking phantoms

This study investigated the mechanical bioeffects exerted by acoustic droplet vaporization (ADV) under different experimental conditions using vessel phantoms with a 200-μm inner diameter but different stiffness for imitating the microvasculature in various tumors. High-speed microscopy, passive cavitation detection, and ultrasound attenuation measurement were conducted to determine the morphological characteristics of vascular damage and clarify the mechanisms by which the damage was initiated and developed. The results show that phantom erosion was initiated under successive ultrasound exposure (2 MHz, 3 cycles) at above 8-MPa peak negative pressures (PNPs) when ADV occurred with inertial cavitation (IC), producing lesions whose morphological characteristics were dependent on the amount of vaporized droplets. Slight injury occurred at droplet concentrations below (2.6±0.2)×10(6) droplets/mL, forming shallow and rugged surfaces on both sides of the vessel walls. Increasing the droplet concentration to up to (2.6±0.2)×10(7) droplets/mL gradually suppressed the damage on the distal wall, and turned the rugged surface on the proximal wall into tunnels rapidly elongating in the direction opposite to ultrasound propagation. Increasing the PNP did not increase the maximum tunnel depth after the ADV efficiency reached a plateau (about 71.6±2.7% at 10 MPa). Increasing the pulse duration effectively increased the maximum tunnel depth to more than 10 times the diameter of the vessel even though there was no marked enhancement in IC dose. It can be inferred that substantial bubble generation in single ADV events may simultaneously distort the acoustic pressure distribution. The backward ultrasound reinforcement and forward ultrasound shielding relative to the direction of wave propagation augment the propensity of backward erosion. The results of the present work provide information that is valuable for the prevention or utilization of ADV-mediated mechanical bioeffects in clinical applications.

Morphological effect of oscillating magnetic nanoparticles in killing tumor cells

Forced oscillation of spherical and rod-shaped iron oxide magnetic nanoparticles (MNPs) via low-power and low-frequency alternating magnetic field (AMF) was firstly used to kill cancer cells in vitro. After being loaded by human cervical cancer cells line (HeLa) and then exposed to a 35-kHz AMF, MNPs mechanically damaged cell membranes and cytoplasm, decreasing the cell viability. It was found that the concentration and morphology of the MNPs significantly influenced the cell-killing efficiency of oscillating MNPs. In this preliminary study, when HeLa cells were pre-incubated with 100 μg/mL rod-shaped MNPs (rMNP, length of 200 ± 50 nm and diameter of 50 to 120 nm) for 20 h, MTT assay proved that the cell viability decreased by 30.9% after being exposed to AMF for 2 h, while the cell viability decreased by 11.7% if spherical MNPs (sMNP, diameter of 200 ± 50 nm) were used for investigation. Furthermore, the morphological effect of MNPs on cell viability was confirmed by trypan blue assay: 39.5% rMNP-loaded cells and 15.1% sMNP-loaded cells were stained after being exposed to AMF for 2 h. It was also interesting to find that killing tumor cells at either higher (500 μg/mL) or lower (20 μg/mL) concentration of MNPs was less efficient than that achieved at 100 μg/mL concentration. In conclusion, the relatively asymmetric morphological rod-shaped MNPs can kill cancer cells more effectively than spherical MNPs when being exposed to AMF by virtue of their mechanical oscillations.

Impact of defoliation on the regrowth capacity and the shoot metabolite profile of Plantago lanceolata L

After defoliation challenges, plants should invest their resources in a way that maximizes their fitness, which may lead to trade-offs in investment in physiological versus chemical traits. Thereby, the regrowth capacity of plants may highly depend on the type and the severity of defoliation. In the present study, we investigated the phenotypic plasticity of Plantago lanceolata L. in response to different defoliation events in a comprehensive way, measuring various traits. This herbaceous species grows on ruderal sites and typically suffers from repeated substantial losses of shoot biomass due to mowing and/or herbivory during the growing season. To study treatment-specific effects of defoliation on resource allocation and induction of defence responses, plants were exposed either to (repeated) mechanical clipping or to herbivory by the generalist Grammia incorrupta (Lepidoptera). Next to regrowth and physiological leaf traits such as the water content, the specific leaf area and C/N ratios of these plants, primary and secondary metabolites in leaves were analyzed with a metabolite profiling approach using gas chromatography coupled with mass spectrometry. The different defoliation treatments strongly affected the regrowth capacity of clipped and herbivore-treated plants, leading to additive changes in physiological leaf traits. As a response to the defoliation treatments, clipped and herbivore-treated plants reduced mainly carbon-based primary metabolites such as sorbitol, and glucose, suggesting that the different defoliation challenges similarly limited the ability of carbon fixation. Yet, only in response to herbivory but not to clipping, plants induced defence compounds, which indicates the importance of treatment-specific responses despite severe resource limitations. Overall, the different responses to defoliation by clipping and herbivory may reflect allocation constraints and/or adaptive plasticity.