Cicada Wings Research Articles

Reversible Antireflection Materials Inspired by Cicada Wings for Anticounterfeit and Photovoltaic Cells.

Antireflection (AR) surfaces are essential for the fields of flexible displays, photovoltaic industry, medical endoscope, intelligent windows, etc. Although natural creatures with well-organized micro/nanostructures have provided some coupling design principles for the rapid development of bioinspired AR materials, the mechanical vulnerability, poor flexibility, and nonadjustability have been pointed out as the drawback of these nanostructures. Here, a bioinspired reversible AR film with 4% reflectivity, 90% transmittance, and 9% haze in broadband (400-900 nm) was prepared. The flexible switching of AR performance enhancement and weakening throughout the visible wavelength band has been achieved by controlling the reversible change in the morphology of the interface structure. A variety of patterned film samples can be obtained by simply changing the template, which can be used in intelligent identification fields such as anticounterfeiting. The cycle test and photoelectric test show that the bionic reversible antireflection structure has certain stability and can effectively reduce the loss of photovoltaic cell conversion efficiency caused by mechanical deformation. It has broad application prospects in the fields of anticounterfeiting, intelligent window, flexible display, photoelectric element, and so on.

Advances in Spiky Antibacterial Materials: From Bioinspired Design to Application

Bacterial infections, particularly those caused by drug‐resistant bacteria, pose a significant threat to human life and health safety. Despite the preparation and application of numerous antibacterial and disinfection materials, addressing their low efficiency and the emergence of drug resistance remains an urgent concern. Inspired by natural spike antibacterial structures such as those found on cicada wings, extensive research has been conducted on biomimetic antibacterial materials with spiky structures. This review provides an overview of the natural spike antibacterial structure and mechanism, introduces surface coatings and micro/nanoparticle materials featuring spike structures inspired by nature, explores microneedle arrays based on spike antibacterial properties, and showcases applications of these innovative antibacterial materials. Finally, potential avenues for optimization and future development directions for antibacterial materials with spike structures are discussed.

Multifaceted roles of NADPH oxidases in the growth and pathogenicity of Beauveria bassiana

ABSTRACT Reactive oxygen species (ROS), synthesized by the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox) complex, are vital molecules in biological cells, influencing various physiological processes such as fungal growth, development, and virulence. Beauveria bassiana, an entomopathogenic fungus, is a promising biopesticide for agricultural, forestry, and urban pest control. This study focuses on the characterization of NADPH oxidases (Noxs) in B. bassiana. Gene expression profiles of Noxs in B. bassiana (BbNoxs) were analysed using RT-qPCR. Knockout strains of single BbNoxA, BbNoxB, BbNoxR, and double BbNoxA and BbNoxB were constructed via homologous recombination, and their phenotypic characteristics were examined. Fungal virulence was evaluated using Galleria mellonella larvae, and infection structures formation and penetration ability were assessed on cicada wings. ROS production and actin assembly during fungal growth and infection were detected using staining and marker methods. Expression analysis revealed significant upregulation of BbNoxs during fungal growth and infection. Compared to the wild-type strain, single knockouts (ΔBbNoxA/B/R) and double knockout (ΔBbNoxAB) of BbNoxs exhibited reduced conidial yields, accelerated conidial germination rates. Deletion of BbNoxB or BbNoxR decreased fungal virulence compared to the WT strain in topical inoculation experiments. Additionally, loss of BbNoxB or BbNoxR impaired infection structures formation, penetration ability, ROS production, and actin aggregation during fungal infection. BbNoxs are crucial for fungal growth, development, and virulence in B. bassiana, playing essential roles in infection structures formation, penetration, ROS production, and actin assembly. Understanding their functions provides insights into B. bassiana’s pathogenic mechanisms.

Silver nanoparticles modified on cicada wings affect fluorescence and Raman signals based on electromagnetic and chemical enhancement mechanisms

The electromagnetic enhancement (EM) mechanism is one of the important theories that need to be mastered to study surface-enhanced fluorescence (SEF) and surface-enhanced Raman scattering (SERS). However, the charge transfer in the chemical enhancement (CM) mechanism has different effects on the two. The study developed a simple and environmentally friendly composite structural substrate by depositing silver (Ag) on the rough surface with regular columnar protuberances of bio-material cicada wings (CW) using magnetron sputtering technology. The formation of Ag nano-islands enhanced the fluorescence and Raman signals of rhodamine 6G (R6G), while the addition of silver nanoparticles (AgNPs) quenched the fluorescence. To explore the magical phenomenon, the electromagnetic field distribution on the surface of the substrate was simulated through three-dimensional finite difference time domain (3D-FDTD), which verified the experimental results of SEF and SERS. The results calculated by Gaussian16 with Density Functional Theory (DFT) and time-dependent density functional theory (TDDFT) explained the effect of adding AgNPs on the surface of the substrate on the fluorescence intensity. The work not only contributes experimental data and theoretical results to the EM mechanism and CM mechanism in enhanced spectra, but also provides ideas for preparing new SEF and SERS substrates.

Superhydrophobic and antibacterial larch wood prepared by PEI controlled growth of conical ZnO nanopillar

The natural antibacterial performance of cicada wings inspired the morphology design and application of zinc oxide (ZnO) nanoparticles on wood surfaces to enhance combined antibacterial function. The commonly interior used larch wood was chosen as base material and firstly pre-treated with ultrasonic-hydrothermal method, the deposition of ZnO nanoparticles with different morphologies was controlled by polyethyleneimine (PEI) concentration during the crystal growth, and the analysis of surface characteristics and antibacterial efficacy was fully tested. Scanning Electron Microscopy (SEM) observations revealed that the addition of PEI altered the morphology of ZnO nanoparticles on the wood surface. ZnO structures without PEI exhibited hexagonal prismatic shapes. As the PEI concentration increased, the particle size of ZnO decreased. When 6 mmol/L of PEI was added, ZnO transformed into a conical structure. Contact angle measurements confirmed the preparation of superhydrophobic ZnO, which exhibited self-cleaning properties. The antibacterial circle method test results showed that superhydrophobic ZnO wood prepared with 6 mmol/L of PEI exhibited superior antibacterial properties, with higher activity against Staphylococcus aureus compared to Escherichia coli. Overall, the study demonstrates a promising approach to developing polyfunctional and effective antibacterial wood surfaces inspired by natural cicada wings nanostructures.

Optimizing alkaline hydrothermal treatment for biomimetic smart metallic orthopedic and dental implants

Orthopedic and dental implant failure continues to be a significant concern due to localized bacterial infections. Previous studies have attempted to improve implant surfaces by modifying their texture and roughness or coating them with antibiotics to enhance antibacterial properties for implant longevity. However, these approaches have demonstrated limited effectiveness. In this study, we attempted to engineer the titanium (Ti) alloy surface biomimetically at the nanometer scale, inspired by the cicada wing nanostructure using alkaline hydrothermal treatment (AHT) to simultaneously confer antibacterial properties and support the adhesion and proliferation of mammalian cells. The two modified Ti surfaces were developed using a 4 h and 8 h AHT process in 1 N NaOH at 230 °C, followed by a 2-hour post-calcination at 600 °C. We found that the control plates showed a relatively smooth surface, while the treatment groups (4 h & 8 h AHT) displayed nanoflower structures containing randomly distributed nano-spikes. The results demonstrated a statistically significant decrease in the contact angle of the treatment groups, which increased wettability characteristics. The 8 h AHT group exhibited the highest wettability and significant increase in roughness 0.72 ± 0.08 µm (P < 0.05), leading to more osteoblast cell attachment, reduced cytotoxicity effects, and enhanced relative survivability. The alkaline phosphatase activity measured in all different groups indicated that the 8 h AHT group exhibited the highest activity, suggesting that the surface roughness and wettability of the treatment groups may have facilitated cell adhesion and attachment and subsequently increased secretion of extracellular matrix. Overall, the findings indicate that biomimetic nanotextured surfaces created by the AHT process have the potential to be translated as implant coatings to enhance bone regeneration and implant integration.Graphical

Preparation and investigation of high-performance flexible and transparent Ag/PDMS substrate with the bionic structure of cicada wings

In this study, an efficient, homogeneous, flexible and transparent Ag/Polydimethylsiloxane (PDMS) substrate with an orderly three-dimensional nanopillar structure was proposed. Ag NPs were thermally deposited on the flexible bionic PDMS support obtained by a two-step replication of cicada wings. Scanning electron microscope images reveal when the deposition time was 50 min, Ag NPs of proper size densely covered the entire PDMS nanopillar surface in the Ag-50/PDMS substrate. Both the gaps between the Ag NPs and those between the nanopillars acted as efficient electric field amplifiers. The enhancement factor (EF) of the Ag-50/PDMS substrate was calculated to be 2.89 × 107 by using crystal violet as the probe molecule. The Ag-50/PDMS substrate also exhibited good uniformity and reproducibility with a relative standard deviation of 1.46% and 11.45% respectively. The detection capability of the proposed flexible and transparent Ag-50/PDMS substrate in practical applications was demonstrated by the in-situ detection of 0.1 ppm malachite green on fish surfaces, indicating its great potential in the field of food monitoring.

Towards silent and efficient flight by combining bioinspired owl feather serrations with cicada wing geometry

As natural predators, owls fly with astonishing stealth due to the serrated feather morphology that produces advantageous flow characteristics. Traditionally, these serrations are tailored for airfoil edges with simple two-dimensional patterns, limiting their effect on noise reduction while negotiating tradeoffs in aerodynamic performance. Conversely, the intricately structured wings of cicadas have evolved for effective flapping, presenting a potential blueprint for alleviating these aerodynamic limitations. In this study, we formulate a synergistic design strategy that harmonizes noise suppression with aerodynamic efficiency by integrating the geometrical attributes of owl feathers and cicada forewings, culminating in a three-dimensional sinusoidal serration propeller topology that facilitates both silent and efficient flight. Experimental results show that our design yields a reduction in overall sound pressure levels by up to 5.5 dB and an increase in propulsive efficiency by over 20% compared to the current industry benchmark. Computational fluid dynamics simulations validate the efficacy of the bioinspired design in augmenting surface vorticity and suppressing noise generation across various flow regimes. This topology can advance the multifunctionality of aerodynamic surfaces for the development of quieter and more energy-saving aerial vehicles.

Eco-friendly epoxidized Eucommia ulmoides gum based composite coating with enhanced super-hydrophobicity and corrosion resistance properties

Developing a green, non-toxic, and sustainable bio-based anticorrosive coating is significant for achieving the objective of "carbon reduction". In this study, superhydrophobic multilayer coatings based on epoxidized Eucommia ulmoides gum were prepared via a layer-by-layer assembly bottom-up approach, providing comprehensive protection for mild steel. The foundational layer, comprising the epoxidized Eucommia ulmoides gum/industrial lignin composite (EEUG-EHL), exhibited commendable adhesion, impermeability, and corrosion resistance. The intermediate layer was composed of 8-hydroxyquinoline/zeolitic imidazolate framework-8 (8HQ@ZIF-8) nanoparticles, which controlled the release of 8HQ through pH responsiveness and had self-healing properties. Employing a spraying method, a top layer with micro-nanostructured consisting of a modified ZIF-8 nanoparticle was created, inspired by the micro-nano structure observed in cicada wings. The multilayer coating exhibited remarkable super-hydrophobicity (contact angle > 150°, sliding angle < 5°), chemical stability, self-cleaning properties, and anti-fouling properties. Notably, the multilayer coating demonstrated exceptional corrosion resistance, maintaining an impedance modulus of 108 ohm cm2 (at 0.01 Hz) after immersion in a 3.5 wt% NaCl solution for 45 days. This work introduces a novel approach to enhance the corrosion protection of metal equipment, aligning with the "green development" strategy and holding significance in advancing marine anti-corrosion construction.

Revolutionizing Antibacterial Surfaces: 3D Printed Nanoscale and Microscale Topographies through Two-Photon Polymerization

The evolving bacteria defense mechanism against antimicrobial agents due to the overuse and misuse of antimicrobial chemicals has led to a catastrophic problem - antimicrobial resistance, this has spurred the quest for innovative antibacterial approach to inhibit bacterial growth effectively without using any chemicals. Tailored nano- and microstructured architecture, inspired by natural nanotopography such as those found on cicada wings, hold great promise in antibacterial activity due to their unique mechano-antibacterial properties. Among the various nano-/microfabrication techniques, the two-photon polymerisation (TPP) stands out as a versatile and precise approach to fabricate arbitrarily functional three-dimensional structures with sub-micrometre resolution. The process involves the use of femtosecond laser pulses to induce polymerization of a biocompatible acrylate-based photoresin in a precise spatial pattern to generate the nano-/microarchitecture. In this study, we investigated the influence of key fabrication parameters, such as laser power, exposure time, and interface value to achieve the final pre-defined nano-/microarchitecture. Microscopy analysis showed that nanostructure of heights between 350-650 nm; 300-400 nm diameter; and increasing center-to-center distances of 700-2000 nm were successfully fabricated. The mechano-antibacterial feasibility of the two photon-designed nanoarchitecture were tested against P. aeruginosa pathogenic bacteria commonly encountered in healthcare settings. Our results showed that the TPP nano-/microarchitecture demonstrated intriguing antibacterial activity through physico-mechanical interactions between the nano-/microarchitectures and bacteria, creating surfaces that exhibit bactericidal activity. This study paves the way for advanced antibacterial applications in the field of nanotechnology and biomedicine, making a significant contribution to the ongoing efforts in combating antimicrobial resistance and promoting global health.

Verifying antibacterial properties of nanopillars on cicada wings

AbstractThe antibacterial properties of cicada wings originate from hexagonally arranged pillar-like multi-functional nanostructures with species-dependent heights, which are super-hydrophobic and self-cleaning. In the present study, two cicada species with promising nanopillars were investigated in more detail. Selected methods were used to analyze the wing surfaces, including Atomic Force Microscopy, Scanning Electron Microscopy, and bacterial tests with live/dead staining. Verifying the antibacterial properties posed challenges, such as the bacteria concentration needed to confirm the antibacterial properties. These challenges will also impact the practical implementation of antibacterial nanostructures and support the findings of recent critical publications.

Realizing a flexible and wavelength-tunable random laser inspired by cicada wings

A bio-tissue-inspired random laser (RL) was successfully demonstrated with a dye-covered silk fibroin replica film (DC-SFRF), created using soft lithography from a cicada's wing. By applying mechanical stress to modify the nanopapillate structure distribution on the film's surface, the DC-SFRF RL exhibits a 13.3 nm blue shift and a decreased speckle contrast.

Influence of temperature on wettability of micro hierarchical rough surfaces: A three-dimensional thermodynamic model

Inspired by the micrometer-scale hierarchical microstructures on the surface of cicada wings, this paper presents a three-dimensional thermodynamic analytical model to comprehensively analyze the superhydrophobicity of rough surfaces with micro-hierarchical structures. Emphasis is placed on the variation of normalized free energy and free energy barrier as a function of apparent contact angle for different wettability states. The effect of temperature-dependent intrinsic contact angle on the intertransition between different wettability states is explored. Additionally, the model allows obtaining the equilibrium contact angle and contact angle hysteresis through corresponding calculations. Importantly, the present model elucidates the influence of the height of the micropillar of the paraboloid on the intertransition between different wettability states at a specific temperature. The geometrical parameters of a droplet in a certain environment, when it is in the final stable wettability state, can be designed based on this model. By conducting a thorough investigation into the effect of temperature on the contact angle of rough surfaces with micro-hierarchical structures, this study offers a fresh perspective for understanding the wettability behavior of droplets at the micrometer scale. Moreover, it provides a theoretical basis for designing rough surfaces with micro-hierarchical structures for application in various environments.

Personalized Machine Learning-Coupled Nanopillar Triboelectric Pulse Sensor for Cuffless Blood Pressure Continuous Monitoring.

A wearable system that can continuously track the fluctuation of blood pressure (BP) based on pulse signals is highly desirable for the treatments of cardiovascular diseases, yet the sensitivity, reliability, and accuracy remain challenging. Since the correlations of pulse waveforms to BP are highly individualized due to the diversity of the patients' physiological characteristics, wearable sensors based on universal designs and algorithms often fail to derive BP accurately when applied on individual patients. Herein, a wearable triboelectric pulse sensor based on a biomimetic nanopillar layer was developed and coupled with Personalized Machine Learning (ML) to provide accurate and continuous monitoring of BP. Flexible conductive nanopillars as the triboelectric layer were fabricated through soft lithography replication of a cicada wing, which could effectively enhance the sensor's output performance to detect weak signal characteristics of pulse waveform for BP derivation. The sensors were coupled with a personalized Partial Least-Squares Regression (PLSR) ML to derive unknown BP based on individual pulse characteristics with reasonable accuracy, avoiding the issue of individual variability that was encountered by General PLSR ML or formula algorithms. The cuffless and intelligent design endow this ML-sensor as a highly promising platform for the care and treatments of hypertensive patients.

Cicada Wing-Inspired Transparent Polystyrene Film Integrating Self-Cleaning, Antifogging, and Antibacterial Properties.

A transparent film integrating antifouling, antifogging, and antibacterial properties is crucial for its application as a protective mask, goggles, or lens. Herein, applying dynamic injection molding coupled with a bionic gradient template, a fast and efficient method is proposed for the preparation of the bionic polystyrene surface (BNPPS) with a cicada wing-inspired nanopillar structure. The contact angle of the BNPPS film increases continuously along the wing vein, while the sliding angle decreases continuously, mimicking the gradient wetting state of a cicada wing and providing excellent self-propelled removal properties for tiny water droplets. Notably, the BNPPS film has a transmittance higher than 90% and a reflectivity lower than 5% in the visible light range. Dyeing water, milk, juice, cola, and ink can slide smoothly from the BNPPS film surface without leaving any residue. Importantly, the nanopillars on the BNPPS film surface can penetrate and kill most of the Escherichia coli within 20 min. Therefore, the prepared BNPPS film with sufficient mechanical strength gathers the unique properties of the cicada wing together. The proposed research is expected to offer valuable guidance for fabricating self-cleaning, antifogging, and antibacterial optical devices that could be utilized in medical and vision systems operating in harsh environments.

AlPO4 film with transparent anti-fogging function imitating cicada wings

Glass surface fogging is a common problem in life. Here we provide a simple method to prepare an anti-fogging AlPO4 array that imitating cicada wings. The size of AlPO4 array can be adjusted by the concentration of the coating solution, the environmental humidity during the drying self-assembly process and the drying time. To explain the mechanism of morphology control, a model analysis was carried out based on surface tension, marangoni convection and a low temperature drying process. It is further realized the regulation of the hierarchical structure through the introduction of self-hygroscopic materials and a multi-step drying process based on the above theoretical model. The size of the array affects its performance. Nano AlPO4 array imitating cicada wing structure has great application value in the anti-fog field because of its high transparency, low haze, super-spreadability and wear resistance. The super-spreading anti-fog performance is achieved through the synergistic effect of surface hydroxyl groups, the bionanometer nanoarray structure and the internal pore structure.

Cicada wing-inspired artificial nanopatterns with antifouling properties for clay adhesion

To clarify the antifouling properties of cicada-inspired nanostructured surfaces and search for a long-term usable antifouling material, the wings of two types of cicadas in Japan, Graptopsaltria nigrofuscata (GN) and Cryptotympana facialis (CF), were examined by surface wettability and surface free energy. Furthermore, considering the complexity and mechanical stability of natural nanostructured surfaces, we mimicked both cicada wing surfaces by combining nanosphere lithography and metal-assisted chemical etching (MacEtch) on Si wafer, which is low-cost and large-area pattern-fabricable. We obtained artificial nanopatterns with pillar pitches of 200, 500, and 1000 nm (naming 200, 500, and 1000 series). As a result, comparing artificial nanopatterns with cicada wings indicated that nanopillar structures with high roughness factors or structural aspect ratios are likely to have excellent hydrophobic properties and antifouling features. Cryptotympana facialis wings and 200 series Si samples showed less clay particle adhesion than other patterns. These results indicate smaller structured surfaces where air may get trapped, resulting in hydrophobic surfaces contributing to self-cleaning or fouling-release properties. Further, reducing the contact area between nanostructures and clay can be used as an effective strategy to prevent clay adhesion has been proposed, but it has targeted limitations. Herein, we present a novel insight that more fine and high-structural-density nanostructural patterns are universal to prevent clay adhesion.

Bactericidal and bioinspired chitin-based anisotropic layer-by-layer brushed-nanocoating

Top-down biomimetic surfaces with micro/nanotopographic features have emerged as a strategy to prevent bacterial attachment and biofilm formation. These nanostructured surfaces mimic the nano-micro topographical features found naturally on cicada wings. However, their development requires expensive equipment and complex processes. Here, inspired by butterfly wings and crustacean exoskeletons, we present the simple design of fully bio-based, anisotropic, and antibacterial layer-by-layer (LbL) coatings based on chitin nanocrystals (ChNCs). Composed exclusively of US Food and Drug Administration-approved materials, the LbL nanocoatings were obtained by manual brushing of ChNC and Tannic Acid (TA), a natural polyphenol, coordinated by iron III (Fe3+). In contrast to those obtained by the dipping method, the brushed TA/Fe3+/ChNC coatings exhibit highly oriented ChNC nanostructures that enable contact-killing antibacterial properties against Staphylococcus aureus (a Gram-positive bacterium) and Escherichia coli (a Gram-negative bacterium). This antibacterial property is due to the orientation of the ChNC into spike-like nanotopographies with a high density of positive charge on the surface. Similar to cicada and dragonfly wings, the positively charged spikes of the oriented ChNC films are likely to damage the bacterial cell wall by (i) puncturing it upon contact with the spikes and/or (ii) stretching and tearing it when a shear force detaches the cell from the highly positive surface. The fully bio-based nature of ChNC-based nanocoatings and their brush-based fabrication method make them a suitable and affordable candidate as a sustainable antibacterial film for (bio)materials in biomedical and environmental applications.

Bionic Plasmonic Nanoarrays Excited by Radially Polarized Vector Beam for Metal-Enhanced Fluorescence

Metal-enhanced fluorescence (MEF) is an important fluorescence technology due to its ability to significantly improve the fluorescence intensity. Here, we present a new MEF configuration of the bionic nanorod array illuminated by radially polarized vector beam (RVB). The bionic nanorod array is fabricated via a nanoimprinting method by using the wings of the Chinese cicada "meimuna mongolica" as bio-templates, and later coating gold film by ion sputtering deposition method. The MEF performance of the prepared substrate is tested by a home-made optical system. The experiment results show that, in the case of RVB excitation, the intensity of fluorescence is more than 10 times stronger with the nano-imprinted substrate than that with glass. Using the bionic nanoarray as a substrate, the intensity of fluorescence is ~2 times stronger via RVB than that by the linearly polarized beam. In addition, the prepared substrate is verified to have good uniformity.

Au@Ag nanodome-cones array substrate for efficient residue analysis of food samples by surface-enhanced Raman scattering

A bioinspired Au@Ag nanodome-cones array (Au@Ag NDCA) surface-enhanced Raman scattering (SERS) chip was developed for efficient residue analyses of food samples. The cicada wing inspired Au@Ag NDCA chip was fabricated by a bottom-up method, Au nanocones array was firstly grown onto nickel foil by displacement reaction and cetyltrimethylammonium bromide guidance growth, and then silver shell with controllable thickness was coated onto the Au nanocones array by magnetron sputtering. The Au@Ag NDCA chip exhibited good SERS performances with high enhancement factor of 1.2 × 108, good uniformity with relative standard deviation (RSD) less than 7.5% (n = 25), good inter-batch reproducibility with RSD less than 9.4% (n = 9), and long-term stability over 9 weeks. By adapting a minimized sample preparation, Au@Ag NDCA chip combined with a 96-well plate could realize high-throughput SERS analyses of 96 samples with average analysis time less than 10 min. The substrate was applied for quantitative analyses of two food projects. One was 6-benzylaminopurine auxin residue in sprout samples with detection limit of 38.8 μg/L, recoveries of 93.3–105.4% and RSDs of 1.5–6.5%, and the other was an edible spice of 4-amino-5,6-dimethylthieno (2,3-d) pyrimidin-2(1H)-one hydrochloride additive in beverage samples with detection limit of 18.0 μg/L, recoveries of 96.2–106.6% and RSDs of 3.5–7.9%. All the SERS results were well confirmed by conventional high-performance liquid chromatographic methods with relative errors less than 9.7%. The robust Au@Ag NDCA chip exhibited good analytical performances possessed great potential for convenient and reliable analyses of food quality and safety.