Bacterial elimination via cell membrane penetration by violet phosphorene peripheral sub-nanoneedles combined with oxidative stress.

The effectiveness of an antibacterial agent is strongly influenced by its antibacterial mechanism, which, in turn, depends on the agent's topological structure. In the natural world, the nanoprotrusions on the surface of insect wings give them excellent antimicrobial properties through physical penetration while being compatible with host cells. Inspired by the novel nanostructure of insect wings, violet phosphorus (VP), a new member of the phosphorus family, has antibacterial potential due to the sub-nanoneedle on its edge. Here, we demonstrate that VP and its exfoliated product, violet phosphorene nanosheets (VPNSs), have superior antibacterial capability against pathogens via cell membrane penetration induced by peripheral sub-nanoneedles combined with oxidative stress. The results show that VPNSs can inactivate more than 99.9% of two common pathogens (Escherichia coli and Staphylococcus aureus) and more than 99.9% of two antibiotic-resistant bacteria (Escherichia coli pUC19 and methicillin-resistant Staphylococcus aureus), while showing almost no toxicity toward normal cells at a high concentration of 2.0 mg mL-1. Moreover, VPNSs can achieve effective treatment of induced skin wound infections and bacterial keratitis (BK) by Staphylococcus aureus and methicillin-resistant Staphylococcus aureus, respectively, showing promising potential for ocular and skin wound infection theragnostics.

Regulation of band gap and localized surface plasmon resonance by loading Au nanorods on violet phosphene nanosheets for photodynamic/photothermal synergistic anti-infective therapy.

In the face of the serious threat to human health and the economic burden caused by bacterial antibiotic resistance, 2D phosphorus nanomaterials have been widely used as antibacterial agents. Violet phosphorus nanosheets (VPNSs) are an exciting bandgap-adjustable 2D nanomaterial due to their good physicochemical properties, yet the study of VPNS-based antibiotics is still in its infancy. Here, a composite of gold nanorods (AuNRs) loaded onto VPNS platforms (VPNS/AuNR) is constructed to maximize the potential of VPNSs for antimicrobial applications. The loading with AuNRs not only enhances the photothermal performance via a localized surface plasmon resonance (LSPR) effect, but also enhances the light absorption capacity due to the narrowing of the band gap of the VPNSs, thus increasing the ROS generation capacity. The results demonstrate that VPNS/AuNR exhibits outstanding antibacterial properties and good biocompatibility. Attractively, VPNS/AuNR is then extensively tested for treating skin wound infections, suggesting promising in vivo antibacterial and wound-healing features. Our findings may open a novel direction to develop a versatile VPNS-based treatment platform, which can significantly boost the progress of VPNS exploration.

Advances in Copper-Based Biomaterials With Antibacterial and Osteogenic Properties for Bone Tissue Engineering.

Treating bone defects coupled with pathogen infections poses a formidable challenge to clinical medicine. Thus, there is an urgent need to develop orthopedic implants that provide excellent antibacterial and osteogenic properties. Of the various types, copper-based biomaterials capable of both regenerating bone and fighting infections are an effective therapeutic strategy for bone tissue engineering and therefore have attracted significant research interest. This review examines the advantages of copper-based biomaterials for biological functions and introduces these materials' antibacterial mechanisms. We summarize current knowledge about the application of copper-based biomaterials with antimicrobial and osteogenic properties in the prevention and treatment of bone infection and discuss their potential uses in the field of orthopedics. By examining both broad and in-depth research, this review functions as a practical guide to developing copper-based biomaterials and offers directions for possible future work.

Physiological and PIP Transcriptional Responses to Progressive Soil Water Deficit in Three Mulberry Cultivars.

Although mulberry cultivars Wubu, Yu711, and 7307 display distinct anatomical, morphological, and agronomic characteristics under natural conditions, it remains unclear if they differ in drought tolerance. To address this question and elucidate the underlying regulatory mechanisms at the whole-plant level, 2-month old saplings of the three mulberry cultivars were exposed to progressive soil water deficit for 5 days. The physiological responses and transcriptional changes of PIPs in different plant tissues were analyzed. Drought stress led to reduced leaf relative water content (RWC) and tissue water contents, differentially expressed PIPs, decreased chlorophyll and starch, increased soluble sugars and free proline, and enhanced activities of antioxidant enzymes in all plant parts of the three cultivars. Concentrations of hydrogen peroxide (H2O2), superoxide anion (O2 •-), and malonaldehyde (MDA) were significantly declined in roots, stimulated in leaves but unaltered in wood and bark. In contrast, except the roots of 7307, soluble proteins were repressed in roots and leaves but induced in wood and bark of the three cultivars in response to progressive water deficit. These results revealed tissue-specific drought stress responses in mulberry. Comparing to cultivar Yu711 and 7307, Wubu showed generally slighter changes in leaf RWC and tissue water contents at day 2, corresponding well to the steady PIP transcript levels, foliar concentrations of chlorophyll, O2 •-, MDA, and free proline. At day 5, Wubu sustained higher tissue water contents in green tissues, displayed stronger responsiveness of PIP transcription, lower concentrations of soluble sugars and starch, lower foliar MDA, higher proline and soluble proteins, higher ROS accumulation and enhanced activities of several antioxidant enzymes. Our results indicate that whole-plant level responses of PIP transcription, osmoregulation through proline and soluble proteins and antioxidative protection are important mechanisms for mulberry to cope with drought stress. These traits play significant roles in conferring the relatively higher drought tolerance of cultivar Wubu and could be potentially useful for future mulberry improvement programmes.

Physiological and Transcriptomic Changes during the Early Phases of Adventitious Root Formation in Mulberry Stem Hardwood Cuttings.

The initiation and induction of root primordia are of great importance for adventitious root (AR) formation in cutting propagation of horticultural and forestry crops. However, the underlying mechanisms orchestrating these early phases of AR formation remain largely unexplored. Here, we investigated the physiological and transcriptomic changes during the early AR phases in mulberry stem hardwood cuttings. The results showed that the concentrations of soluble proteins increased, whereas concentrations of soluble sugars and starch were decreased. Indole-3-acetic acid (IAA) and zeatin had a rapid transit peak at 6 h after planting (hAP) and declined thereafter. The activities of peroxidase and catalase persistently increased and indole-3-acetic acid oxidase was maintained at a higher stable level from 0 hAP, while the activities of polyphenol oxidase fluctuated with soluble phenolics and IAA levels. The comparative transcriptome identified 4276 common genes that were differentially regulated at -6, 0 and 54 hAP. They were separated into five clusters with distinct biological functions such as defense response and photosynthesis. Considerable common genes were assigned to pathways of sugar metabolism, mitogen-activated protein kinase, and circadian rhythm. The gene co-expression network analysis revealed three major co-expressed modules involved in stress responses, hormone signaling, energy metabolism, starch metabolism, and circadian rhythm. These findings demonstrate the positive effect of auxin on AR induction, and uncovered the crucial roles of stress responses, hormone signaling and circadian rhythm in coordinating the physiological changes during the early phases of AR formation in mulberry stem hardwood cuttings.

Determinants of Shoot Biomass Production in Mulberry: Combined Selection with Leaf Morphological and Physiological Traits.

Physiological and morphological traits have a considerable impact on the biomass production of fast-growing trees. To compare cultivar difference in shoot biomass and investigate its relationships with leaf functional traits in mulberry, agronomic traits and 20 physiological and morphological attributes of 3-year-old mulberry trees from eight cultivars growing in a common garden were analyzed. The cultivars Xiang7920, Yu711, and Yunsang2 had higher shoot fresh biomass (SFB), which was closely associated with their rapid leaf expansion rate, large leaf area, and high stable carbon isotope composition (δ13C). Conversely, the cultivars 7307, Husang32, Wupu, Yunguo1, and Liaolu11 were less productive, and this was primarily the result of slower leaf expansion and smaller leaf size. Growth performance was negatively correlated with leaf δ13C and positively correlated with the total nitrogen concentration, indicating that a compromise exists in mulberry between water use efficiency (WUE) (low δ13C) and high nitrogen consumption for rapid growth. Several morphological traits, including the maximum leaf area (LAmax), leaf width and length, petiole width and length, leaf number per shoot, and final shoot height were correlated with SFB. The physiological traits that were also influential factors of shoot biomass were the leaf δ13C, the total nitrogen concentration, and the water content. Among the studied leaf traits, LAmax, leaf δ13C, and concentrations of chlorophyll a and b were identified as the most representative predictor variables for SFB, accounting for 73% of the variability in SFB. In conclusion, a combination of LAmax, leaf δ13C, and chlorophyll should be considered in selection programs for high-yield mulberry cultivars.