Diatom Frustule Silica Exhibits Superhydrophilicity and Superhemophilicity

Gluing blood into adhesive gel by oppositely charged polysaccharide dry powder inspired by fibrin fibers coagulation mediator

Hemostatic powders that adapt to irregularly shaped wounds, allowing for easy application and stable storage, have gained popularity for first-aid hemorrhage control. However, traditional powders often provide weak thrombus support and exhibit limited tissue adhesion, making them susceptible to dislodgment by the bloodstream. Inspired by fibrin fibers coagulation mediator, we have developed a bi-component hemostatic powder composed of positively charged quaternized chitosan (QCS) and negatively charged catechol-modified alginate (Cat-SA). Upon application to the wound, the bi-component powders (QCS/Cat-SA) rapidly absorb plasma and dissolve into chains. These chains interact with each other to form a network, which can effectively bind and entraps clustered red blood cells and platelets, ultimately leading to the creation of a durable and robust thrombus. Significantly, these interconnected polymers adhere to the injury site, offering protection against thrombus disruption caused by the bloodstream. Benefiting from these synthetic properties, QCS/Cat-SA demonstrates superior hemostatic performance compared to commercial hemostatic powders like Celox™ in both arterial injuries and non-compressible liver puncture wounds. Importantly, QCS/Cat-SA exhibits excellent antibacterial activity, cytocompatibility, and hemocompatibility. These advantages of QCS/Cat-SA, including strong blood clotting, wet tissue adherence, antibacterial activity, biosafety, ease of use, and stable storage, make it a promising hemostatic agent for emergency situations.

Lysis-Free Isolation and Direct Amplification of Pathogenic Bacterial DNA Using Diatom Frustules

DNA has been implicated as an important biomarker for the diagnosis of bacterial infections. Herein, we developed a streamlined methodology that uses diatom frustules (DFs) to liberate and capture bacterial DNA and allows direct downstream amplification tests without any lysis, washing, or elution steps. Unlike most conventional DNA isolation methods that rely on cell lysis to release bacterial DNA, DFs can trigger the oxidative stress response of bacterial cells to promote bacterial membrane vesicle formation and DNA release by generating reactive oxygen species in aqueous solutions. Due to the hierarchical porous structure, DFs provided high DNA capture efficiency exceeding 80% over a wide range of DNA amounts from 10 pg to 10 ng, making only 10 μg DFs sufficient for each test. Since laborious liquid handling steps are not required, the entire DNA sample preparation process using DFs can be completed within 3 min. The diagnostic use of this DF-based methodology was illustrated, which showed that the DNA of the pathogenic bacteria in serum samples was isolated by DFs and directly detected using polymerase chain reaction (PCR) at concentrations as low as 102 CFU/mL, outperforming the most used approaches based on solid-phase DNA extraction. Furthermore, most of the bacterial cells were still alive after DNA isolation using DFs, providing the possibility of recycling samples for storage and further diagnosis. The proposed DF-based methodology is anticipated to simplify bacterial infection diagnosis and be broadly applied to various medical diagnoses and biological research.

Diatom Biosilica Functionalised with Metabolically Deposited Cerium Oxide Nanoparticles

This study introduces a novel approach to synthesising a three-dimensional (3D) micro-nanostructured amorphous biosilica. The biosilica is coated with cerium oxide nanoparticles obtained from laboratory-grown unicellular photosynthetic algae (diatoms) doped metabolically with cerium. This unique method utilises the ability of diatom cells to absorb cerium metabolically and deposit it on their silica exoskeleton as cerium oxide nanoparticles. The resulting composite (Ce-DBioSiO2) combines the unique structural and photonic properties of diatom biosilica (DBioSiO2) with the functionality of immobilised CeO2 nanoparticles. The kinetics of the cerium metabolic insertion by diatom cells and the physicochemical properties of the obtained composites were thoroughly investigated. The resulting Ce-DBioSiO2 composite exhibits intense Stokes fluorescence in the violet-blue region under ultraviolet (UV) irradiation and anti-Stokes intense violet and faint green emissions under the 800 nm near-infrared excitation with a xenon lamp at room temperature in an ambient atmosphere.

Biomimetic Materials for Skin Tissue Regeneration and Electronic Skin

Biomimetic materials have become a promising alternative in the field of tissue engineering and regenerative medicine to address critical challenges in wound healing and skin regeneration. Skin-mimetic materials have enormous potential to improve wound healing outcomes and enable innovative diagnostic and sensor applications. Human skin, with its complex structure and diverse functions, serves as an excellent model for designing biomaterials. Creating effective wound coverings requires mimicking the unique extracellular matrix composition, mechanical properties, and biochemical cues. Additionally, integrating electronic functionality into these materials presents exciting possibilities for real-time monitoring, diagnostics, and personalized healthcare. This review examines biomimetic skin materials and their role in regenerative wound healing, as well as their integration with electronic skin technologies. It discusses recent advances, challenges, and future directions in this rapidly evolving field.

Towards promoting wound healing: A near-infrared light-triggered persistently antibacterial, synergistically hemostatic nanoarchitecture-integrated chitosan hydrogel

The skin, the primary barrier of the body, is inevitably broken. However, the development of materials that facilitate wound healing with sustained antimicrobial, hemostatic, and biocompatible properties remains a formidable challenge. In this article, we prepared a photopolymerizable composite hydrogel consisting of a hydrogel matrix, a hemostatic/antibacterial agent, and a photothermal therapy agent. The photopolymerizable hydrogel matrix was prepared by grafting the photoinitiator and polymerizable active monomer onto the chitosan chain segment, which exhibits excellent biocompatibility. Furthermore, linalool is adsorbed on the surface of halloysite nanotubes (HNTs) to form a hemostatic and antibacterial. Meanwhile, dopamine is employed as a coating material for hollow glass microsphere (HGM), which enables them to function as photothermal therapy agents. Upon exposure to near-infrared radiation, the PHA hydrogel releases linalool molecules from the surface of the HNTs, which diffuse into the hydrogel matrix, resulting in a sustained antimicrobial effect. At the same time, rapid curing of the photopolymerizable hydrogel under UV light forms a physical barrier that synergistically enhances the hemostatic properties of the HNTs. From the above, the results pave the way to develop a potential hemostatic antimicrobial dressing for clinical use in wound healing.

The Art of Exploring Diatom Biosilica Biomaterials: From Biofabrication Perspective

Diatom is a common single-cell microalgae with large species and huge biomass. Diatom biosilica (DB), the shell of diatom, is a natural inorganic material with a micro-nanoporous structure. Its unique hierarchical porous structure gives it great application potential in drug delivery, hemostat materials, and biosensors, etc. However, the structural diversity of DB determines its different biological functions. Screening hundreds of thousands of diatom species for structural features of DB that meet application requirements is like looking for a needle in a seaway. And the chemical modification methods lack effective means to control the micro-nanoporous structure of DB. The formation of DB is a typical biomineralization process, and its structural characteristics are affected by external environmental conditions, genes, and other factors. This allows to manipulate the micro-nanostructure of DB through biological regulation method, thereby transforming the screening mode of the structure function of DB from a needle in a seaway to biofabrication mode. This review focuses on the formation, biological modification, functional activity of DB structure, and its application in biomaterials field, providing regulatory strategies and research idea of DB from the perspective of biofabrication. It will also maximize the possibility of using DB as biological materials.

An evolutionary history of F12 gene: Emergence, loss, and vulnerability with the environment as a driver

In the context of macroevolutionary transitions, environmental changes prompted vertebrates already bearing genetic variations to undergo gradual adaptations resulting in profound anatomical, physiological, and behavioral adaptations. The emergence of new genes led to the genetic variation essential in metazoan evolution, just as was gene loss, both sources of genetic variation resulting in adaptive phenotypic diversity. In this context, F12-coding protein with defense and hemostatic roles emerged some 425 Mya, and it might have contributed in aquatic vertebrates to the transition from water-to-land. Conversely, the F12 loss in marine, air-breathing mammals like cetaceans has been associated with phenotypic adaptations in some terrestrial mammals in their transition to aquatic lifestyle. More recently, the advent of technological innovations in western lifestyle with blood-contacting devices and harmful environmental nanoparticles, has unfolded new roles of FXII. Environment operates as either a positive or a relaxed selective pressure on genes, and consequently genes are selected or lost. FXII, an old dog facing environmental novelties can learn new tricks and teach us new therapeutic avenues.

The hierarchical porous structures of diatom biosilica-based hemostat: From selective adsorption to rapid hemostasis

Here, we developed a Ca2+ modified diatom biosilica-based hemostat (DBp-Ca2+) with a full scale hierarchical porous structure (pore sizes range from micrometers to nanometers). The unique porous size in stepped arrangement of DBp-Ca2+give it selective adsorption capacity during coagulation process, resulted in rapid hemorrhage control. Based on in vitro and in vivo studies, it was confirmed that the primary micropores of DBp-Ca2+gave it high porosity to hold water (water absorption: 78.46 ± 1.12 %) and protein (protein absorption: 83.7 ± 1.33 mg/g). Its secondary mesopores to macropores could reduce of water diffusion length to accelerate blood exchange (complete within 300 ms). The tertiary stacking pores of DBp-Ca2+ could absorb platelets and erythrocytes to reduce more than 50 % of thrombosis time, and provided enough contact between Ca active site and coagulation factors for triggering clotting cascade reaction. This work not only developed a novel DBs based hemostat with efficient hemorrhage control, but also provided new insights to study procoagulant mechanism of inorganic hemostat with hierarchical porous structure from selective adsorption to rapid hemostasis.

Diatom-Inspired Bionic Hydrophilic Polysaccharide Adhesive for Rapid Sealing Hemostasis

Diatoms are typical marine biofouling organisms that secrete extracellular polymers (EPS) to achieve strong underwater adhesion. Here, we report a diatom-inspired bionic hydrophilic polysaccharide adhesive composed of diatom biosilica (DB) and bletilla striata polysaccharide (BSP) for rapid sealing hemostasis. The hierarchical porous structure of DB with rich surface silanol groups provides a strong anchored interface effect for BSP, which can significantly enhance cross-linking density and interaction strength of the hydrophilic macromolecular network. BSP/DB adhesive offers 6 times greater mechanical strength and viscosity over BSP under different temperature conditions. The aggregation effect of DBs interface for BSP avoided the washout of BSP/DB adhesive during application in a wet environment before cross-linking occurs. This strengthened the adhesion ability of BSP/DB adhesive to biological tissue that brought out complete sealing hemostasis without blood loss in a rat liver injury model. The dry BSP/DB prepared by lyophilization inherited excellent clotting ability of BSP/DB adhesive, which could realize rapidly the cruor of anticoagulant whole blood within 1 min. The results of animal studies confirmed that dry BSP/DB exhibited superior hemostatic performance over silicate-based inorganic Quikclot, in terms of hemostatic rate, blood loss, dosage, and multiscroll wound closure.

Recent Progress in Diatom Biosilica: A Natural Nanoporous Silica Material as Sustained Release Carrier

A drug delivery system (DDS) is a useful technology that efficiently delivers a target drug to a patient's specific diseased tissue with minimal side effects. DDS is a convergence of several areas of study, comprising pharmacy, medicine, biotechnology, and chemistry fields. In the traditional pharmacological concept, developing drugs for disease treatment has been the primary research field of pharmacology. The significance of DDS in delivering drugs with optimal formulation to target areas to increase bioavailability and minimize side effects has been recently highlighted. In addition, since the burst release found in various DDS platforms can reduce drug delivery efficiency due to unpredictable drug loss, many recent DDS studies have focused on developing carriers with a sustained release. Among various drug carriers, mesoporous silica DDS (MS-DDS) is applied to various drug administration routes, based on its sustained releases, nanosized porous structures, and excellent solubility for poorly soluble drugs. However, the synthesized MS-DDS has caused complications such as toxicity in the body, long-term accumulation, and poor excretion ability owing to acid treatment-centered manufacturing methods. Therefore, biosilica obtained from diatoms, as a natural MS-DDS, has recently emerged as an alternative to synthesized MS-DDS. This natural silica carrier is an optimal DDS platform because culturing diatoms is easy, and the silica can be separated from diatoms using a simple treatment. In this review, we discuss the manufacturing methods and applications to various disease models based on the advantages of biosilica.

Synergetic Effects of Nanoscale ALD-HfO2 Coatings and Bionic Microstructures for Antiadhesive Surgical Electrodes: Improved Cutting Performance, Antibacterial Property, and Biocompatibility

The high temperature induced by surgical electrodes is highly susceptible to severe surface adhesion and thermal damage to adjacent tissues, which is a major challenge in improving the quality of electrosurgery. Herein, we reported a coupled electrode with micro/nano hierarchical structures fabricated by depositing nanoscale hafnium oxide (HfO2) coatings on bionic microstructures (BMs) via laser texturing, acid washing, and atomic layer deposition (ALD) techniques. The synergistic effect of HfO2 coatings and BMs greatly enhanced the hemophobicity of the electrode with a blood contact angle of 162.15 ± 3.16°. Furthermore, the coupled surface was proven to have excellent antiadhesive properties to blood when heated above 100 °C, and the underlying mechanism was discussed. Further experiments showed that the coupled electrode had significant advantages in reducing cutting forces, thermal damage, and tissue adhesion mass. Moreover, the antibacterial rates against Escherichia coli and Staphylococcus aureus were 97.2% and 97.9%, respectively. In addition, the noncytotoxicity levels of HfO2 coatings were verified by cell apoptosis and cycle assays, indirectly endowing the coupled electrode with biocompatibility. Overall, the coupled electrode was shown to have broad potential for application in the field of electrosurgery, and this work could provide new insights into antiadhesion properties under high-temperature conditions.

Less-Suture Vascular Anastomosis: Development of Alternative Protocols with Multifunctional Self-Wrapping, Transparent, Adhesive, and Elastic Biomaterials

Blood vessel anastomosis by suture is a life-saving, yet time-consuming and labor-intensive operation. While suture-less alternatives utilizing clips or related devices are developed to address these shortcomings, suture anastomosis is still overwhelmingly used in most cases. In this study, practical "less-suture" strategies are proposed, rather than ideal "suture-less" methods, to reflect real-world clinical situations. In the case of rat artery (d = 0.64 mm) anastomosis, the less-suture anastomosis involves the application of thin, adhesive, transparent, and self-wrapping films to the site. This surprisingly reduces the number of stitches required from ten (without films) to four (with films), saving 27 min of operating time per vessel. Furthermore, the decreased number of stitches largely alleviates fibrosis-mediated wall-thickening. Thus, a less-suture strategy is particularly useful for anastomosis of multiple vessels in emergency conditions and small-diameter vessels.

Limit-Defying μ-Total Analysis System: Achieving Part-Per-Quadrillion Sensitivity on a Hierarchical Optofluidic SERS Sensor

Optofluidic sensors have accelerated the growth of smart sensor platforms with improved sensitivity, reliability, and innovation. In this article, we report the integration of a surface-enhanced Raman scattering (SERS) material consisting of silver nanoparticle-decorated diatomaceous earth (AgNPs-DE) with a flow-through microfluidic device, building up a hierarchical structured micro-total analysis system (μ-TAS) capable of achieving part-per-quadrillion (ppq)-level sensitivity. By the synergic integration of millimeter-scale microfluidic devices and porous laboratory filter paper with a micrometer-sized crosslinked cellulosic network that carries SERS-active AgNPs-DE, which possesses submicron to nanometer regimes of photonic crystals and plasmonic nanostructures, we achieved enhanced mass-transfer efficiency and unprecedented detection sensitivity. In our experiment, fentanyl as the testing analyte at different concentrations was measured using a portable Raman spectrometer. The limit of detection (LOD) was estimated to be 10 ppq from a small detection volume of 10 mL with an ultrafast time of sensing (TOS) of 3 min. To attain comparable signals, the traditional soaking method took more than 90 min to detect 10 part-per-trillion fentanyl from a 10 mL sample. Compared with existing SERS sensing results of fentanyl, the limit-defying μ-TAS reduced the LOD-TOS product by almost 4 orders of magnitude, which represents a new stage of ultrafast sensing of extremely low concentration analytes.

Yeast cell templated porous hollow silica spheres for rapid hemostasis accompanied by antibacterial action

Uncontrolled haemorrhage is the leading cause in nearly 91% of pre-hospital deaths, which were considered potentially survivable. In particular, severe trauma is susceptible to infection, which further affects the natural healing process and can even lead to life-threatening sepsis. Therefore, we established Ag@HMSN nanocomposites based on a yeast cell template that combines hemostasis with antibiosis and further studied the effects of different calcination temperatures on the hemostatic and antibacterial properties. From the experimental results, Ag@HMSNs/500 shows excellent bactericidal effect on a mouse skin infection model and outstanding hemostatic effect on a mouse liver injury model, which could be used as the next-generation hemostatic and antibacterial material.

Super Water-Storage Self-Adhesive Gel for Solar Vapor Generation and Collection

Water treatment consumes lots of energy from fossil fuels nowadays, and the emission of CO₂ enhances the temperature on earth, resulting in more and more hazards. Thus, clean water production enabled by green energy without CO₂ emission is attracting more and more attention. Herein, we propose a novel solar evaporation system achieving both solar evaporation and water storage with two different unique hydrogels based on a three-dimensional (3D) printing technique. The hydrogel absorber demonstrates an ultrahigh absorptance (98.2%) of solar light, while the water-storage hydrogel absorbs more than 100 times its own weight of water, demonstrating super water-storage performance with strong self-adhesiveness. The solar vapor generation rate can be as high as 3.14 kg·m^-2·h^-1, with a solar evaporation efficiency up to 91.2% irradiated by 1.43 sun. Furthermore, our environmentally friendly solar evaporation system achieves ultrahigh water purification efficiency of 99.99% for salt, heavy ions, and acid/alkaline with remarkable stability and durability. Our solar evaporation system promises long-lasting applications for the hydrological cycle enabled by solar energy, such as seawater desalination, sterilization, wastewater purification, and so on.

Inorganic-based biomaterials for rapid hemostasis and wound healing

The challenge for the treatment of severe traumas poses an urgent clinical need for the development of biomaterials to achieve rapid hemostasis and wound healing. In the past few decades, active inorganic components and their derived composites have become potential clinical products owing to their excellent performances in the process of hemorrhage control and tissue repair. In this review, we provide a current overview of the development of inorganic-based biomaterials used for hemostasis and wound healing. We highlight the methods and strategies for the design of inorganic-based biomaterials, including 3D printing, freeze-drying, electrospinning and vacuum filtration. Importantly, inorganic-based biomaterials for rapid hemostasis and wound healing are presented, and we divide them into several categories according to different chemistry and forms and further discuss their properties, therapeutic mechanisms and applications. Finally, the conclusions and future prospects are suggested for the development of novel inorganic-based biomaterials in the field of rapid hemostasis and wound healing.

Large-scale preparation of a versatile bioinspired sponge with physic-mechanochemical robustness for multitasking separation

Developing novel biomaterials integrating robustness and multitasking separation performance are of importance. However, those were limited in application due to the expensive, time-consuming and complex fabrication process. In this work, with the inspiration from high porosity and surface area of natural materials, the porous superhydrophobic melamine sponges (SMS) coated hydrophobic TiO₂ and epoxy copolymer were fabricated via a facile, inexpensive, eco-friendly and large-scale strategy. The SMS showed excellent superhydrophobic property, and could well resist the harsh mechanical damage, chemical corrosion, extreme temperature, and irradiation of UV without losing antiwetting ability. Besides, it displayed selective oil absorbing ability, recyclability, and self-cleaning ability. Moreover, the SMS displayed superior multitasking performance for continuous oil/water separation, surfactant-stabilized O/W emulsions separation (separation efficiency above 99%), and bacterial/fungus containing filtration (filtration efficiency over 60% for S. aureus, 90% for E. coli and C. albicans). With the multifaceted features, the SMS is a promising sponge material for treatment of industry oily or bacterial/fungus-containing wastewater in practical application.

Engineered Hemostatic Biomaterials for Sealing Wounds

Hemostatic biomaterials show great promise in wound control for the treatment of uncontrolled bleeding associated with damaged tissues, traumatic wounds, and surgical incisions. A surge of interest has been directed at boosting hemostatic properties of bioactive materials via mechanisms triggering the coagulation cascade. A wide variety of biocompatible and biodegradable materials has been applied to the design of hemostatic platforms for rapid blood coagulation. Recent trends in the design of hemostatic agents emphasize chemical conjugation of charged moieties to biomacromolecules, physical incorporation of blood-coagulating agents in biomaterials systems, and superabsorbing materials in either dry (foams) or wet (hydrogel) states. In addition, tough bioadhesives are emerging for efficient and physical sealing of incisions. In this Review, we highlight the biomacromolecular design approaches adopted to develop hemostatic bioactive materials. We discuss the mechanistic pathways of hemostasis along with the current standard experimental procedures for characterization of the hemostasis efficacy. Finally, we discuss the potential for clinical translation of hemostatic technologies, future trends, and research opportunities for the development of next-generation surgical materials with hemostatic properties for wound management.

Antagonistically Functionalized Diatom Biosilica for Bio-Triboelectric Generators

Although biomaterial-based triboelectric nanogenerators (Bio-TENGs) for use in wearable electronics and implantable sensors have been developed, power generation is not suitable for satisfying the basic requirements for practical applications. Here, to greatly enhance output performances of Bio-TENG devices, an antagonistic approach of diatom frustules (DFs) with amine and fluorine chemical functionalizations is reported. The DFs are treated with piranha solution to increase the density of hydroxyl groups and tribo-positive and tribo-negative composite films are designed with antagonistically functionalized DFs. The tribo-positive composites having electron donating functionality consist of aminated DFs and cellulose nanocrystals (CNCs), while the tribo-negative composite is composed of fluorinated DFs and polydimethylsiloxane (PDMS). An antagonistically and chemically functionalized TENG (ACF TENG) with an efficient contact area of 9.6 cm² under a force of 8 N and a frequency of 5 Hz exhibits an output voltage of 248 V, a short-circuit current of 16.4 µA, and a power density of 2.01 W m^-2 , which is 16.6 times higher than a reference (CNC:PDMS) TENG. This study shows a simple antagonistic approach for chemical functionalization as an efficient method to manipulate the tribo-polarity of bio-additives for enhancing power generation of Bio-TENGs.

MXene-Enhanced Chitin Composite Sponges with Antibacterial and Hemostatic Activity for Wound Healing

This study shows the effective use of MXene-based nanomaterials to improve the performance of biocomposite sponges in wound healing. In this way, diverse chitin/MXene composite sponges are fabricated by incorporating MXene-based nanomaterials with various morphology (accordion-shaped, intercalated, single-layer, gold nanoparticles (AuNPs)-loaded single-layer) into the network of chitin sponge (CH), which can prevent massive blood losses and promote the healing process of bacterial-infected wounds. With the addition of MXene-based nanomaterials, the hemostatic efficacy of CH is enhanced due to the improved hemophilicity and accelerated blood coagulation kinetics. Furthermore, the composite sponges show a predominant antibacterial activity through the synergy between the capture and the photothermal effects. Importantly, the addition of AuNPs to composite sponges further improves hemostatic performance and promotes normal skin cell migration to heal the infected wound, achieving wound closure rates of 84% on day 9. These initial studies expand the applications of MXene-based nanomaterials in biomedical fields.

Recent advances in materials for hemostatic management

Traumatic hemorrhage can be a fatal event, particularly when large quantities of blood are lost in a short period of time. Therefore, hemostasis has become a crucial part of emergency treatment. For small wounds, hemostasis can be achieved intrinsically depending on the body's own blood coagulation mechanism; however, for large-area wounds, particularly battlefield and complex wounds, materials delivering rapid and effective hemostasis are required. In parallel with the constant progress in science, technology, and society, advances in hemostatic materials have also undergone various iterations by integrating new ideas with old concepts. There are various natural and synthetic hemostatic materials, including hemostatic powders, adhesives, hydrogels, and tourniquets, for the treatment of severe external trauma. This review covers the differences among the currently available hemostatic materials and comprehensively describes the hemostatic effects of different materials based on the underlying mechanisms. Finally, solutions for current issues related to trauma bleeding are discussed, and the prospects of hemostatic materials are proposed.

Diatomaceous earth/zinc oxide micro-composite assisted antibiotics in fungal therapy

As the second wave of COVID-19 hits South Asia, an increasing deadly complication 'fungal infections (such as Mycosis, Candida and Aspergillus) outbreak' has been raised concern about the insufficient technologies and medicals for its diagnosis and therapy. Biosilica based nano-therapy can be used for therapeutic efficacy, yet their direct role as antibiotic agent with biocompatibility and stability remains unclear. Here, we report that a diatomaceous earth (DE) framework semiconductor composite conjugated DE and in-house synthesized zinc oxide (DE-ZnO), as an antibiotic agent for the enhancement of antibiotic efficacy and persistence. We found that the DE-ZnO composite had enhanced antibiotic activity against fungi (A. fumigatus) and Gram-negative bacteria (E. coli, S. enterica). The DE-ZnO composite provides enhancing large surface areas for enhancement of target pathogen binding affinity, as well as produces active ions including reactive oxygen species and metal ion for breaking the cellular network of fungi and Gram-negative bacteria. Additionally, the toxicity of DE-ZnO with 3 time less amount of dosage is 6 times lower than the commercial SiO₂-ZnO. Finally, a synergistic effect of DE-ZnO and existing antifungal agents (Itraconazole and Amphotericin B) showed a better antifungal activity, which could be reduced the side effects due to the antifungal agents overdose, than a single antibiotic agent use. We envision that this DE-ZnO composite can be used to enhance antibiotic activity and its persistence, with less-toxicity, biocompatibility and high stability against fungi and Gram-negative bacteria which could be a valuable candidate in medical science and industrial engineering.

Thrombin immobilized polydopamine-diatom biosilica for effective hemorrhage control

In this study, an efficient composite hemostatic material (DA-diatom-T) was prepared, using a polydopamine layer as a linker to immobilize thrombin on the surface of diatom biosilica. DA-diatom-T retained the porous structure of the diatom with high water absorption capacity, which can absorb 31 times its own weight of water. The thrombin activity of DA-diatom-T was as high as 5.81 U mg-1 that could be maintained at 67% after 30 days at room temperature. DA-diatom-T exhibited non-toxicity to mouse fibroblast cell lines, favorable hemocompatibility and fast procoagulant ability. DA-diatom-T could promote the initiation of the coagulation process and increase platelet activity and blood clot strength to form a physical barrier at the wound. In an in vivo study, DA-diatom-T could significantly reduce the clotting time and reduce the bleeding volume. The above results showed that DA-diatom-T had potential as a new hemostatic material.

Study on the Hemostasis Characteristics of Biomaterial Frustules Obtained from Diatom Navicula australoshetlandica sp

Diatoms, known as photosynthetic unicellular algae, can produce natural biosilica frustules that exhibit great biocompatibility, superhydrophilicity, and superhemophilicity. In our study, the diatom Navicula australoshetlandica sp. was isolated from aquaculture wastewater and pretreated to obtain frustules so as to explore their hemostasis characteristics. A special “porous web” (6–8 nm) substructure in the ordered nanopores (165–350 nm) of boat-shaped diatom frustule was observed in Navicula australoshetlandica sp. using SEM and TEM analysis. Moreover, X-ray, N₂ adsorption–desorption isotherms, and BET analysis showed that the diatom frustule is a mesoporous material with a surface area of 401.45 m² g⁻¹ amorphous silica. FTIR analysis showed that Navicula australoshetlandica sp. frustules possessed abundant OH functional groups. A low hemolysis ratio was observed for 1–5 mg mL⁻¹ diatom frustules that did not exceed 1.55 ± 0.06%, which indicates favorable hemocompatibility. The diatom frustules exhibited the shortest clotting time (134.99 ± 7.00 s) with a hemostasis material/blood (mg/μL) ratio of 1:100, which is 1.83 times (112.32 s) shorter than that of chitosan. The activated partial thromboplastin time (aPTT) of diatom frustule was also 44.53 s shorter than the control. Our results demonstrate the potential of Navicula australoshetlandica sp. diatom frustules to be used as medical hemostasis material.

A composite sponge based on alkylated chitosan and diatom-biosilica for rapid hemostasis

Rapid control of bleeding is of great significance in military trauma and traffic accidents. In this study, alkylated chitosan (AC) and diatom biosilica (DB) were combined to develop a safe and effective hemostatic composite sponge (AC-DB sponge) for hemorrhage control. Due to the procoagulant chemical structure of AC-DB sponge, it exhibited rapid hemostatic ability in vitro (clotting time was shortened by 78% than that of control group), with favorable biocompatibility (hemolysis ratio < 5%, no cytotoxicity). The strong interface effect between AC-DB sponge and blood induced the erythrocyte and platelets activation, deformation and aggregation, intrinsic coagulation pathway activation, resulting in significant coagulation acceleration. AC-DB sponge had excellent performance in in vivo assessments with shortest clotting time (106.2 s) and minimal blood loss (328.5 mg). All above results proved that AC-DB sponge had great potential to be a safe and rapid hemostatic material.

Magnetic field-mediated Janus particles with sustained driving capability for severe bleeding control in perforating and inflected wounds

Severe bleeding in perforating and inflected wounds with forky cavities or fine voids encountered during prehospital treatments and surgical procedures is a complex challenge. Therefore, we present a novel hemostatic strategy based on magnetic field-mediated guidance. The biphasic Janus magnetic particle (MSS@Fe₂O₃-T) comprised aggregates of α-Fe₂O₃ nanoparticles (Fe₂O₃ NPs) as the motion actuator, negatively modified microporous starch (MSS) as the base hemostatic substrate, and thrombin as the loaded hemostatic drug. Before application, the particles were first wrapped using NaHCO₃ and then doped with protonated tranexamic acid (TXA-NH₃⁺), which ensured their high self-dispersibility in liquids. During application, the particles promptly self-diffused in blood by bubble propulsion and travelled to deep bleeding sites against reverse rushing blood flow under magnetic guidance. In vivo tests confirmed the superior hemostatic performance of the particles in perforating and inflected wounds (“V”-shaped femoral artery and “J”-shaped liver bleeding models). The present strategy, for the first time, extends the range of magnetically guided drug carriers to address the challenges in the hemorrhage control of perforating and inflected wounds.

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A new Janus hemostat was developed for treating severe bleeding.

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The “J” shape bleeding model was proposed for hemostatic test.

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Magnetic field-mediated driving capacity was employed for hemostasis.

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Explosive self-dispersibility endowed to the hemostat largely enhanced the bleeding control capacity.

Diatom Silica/Polysaccharide Elastomeric Hydrogels: Adhesion and Interlocking Synergy

The addition of particles during the sol-to-gel conversion process generally enhances the mechanical properties of the resulting hydrogels. However, the impact of the addition of porous particles during such a process remains an open question. Herein, we report hydrogel-to-elastomer conversions by natural porous particles called diatom frustule silica, namely, Melosira nummuloides. The surface pores provide mechanical interlocking points for polymers that are reinforced by gelation. The most critical aspect when choosing polymeric materials is the presence of water-resistant adhesion moieties, such as catechol, along a polymer chain, such as chitosan. Without catechol, no sol-to-gel conversion is observed; thus, no elastomeric hydrogel is produced. The resulting hybrid gel reveals reversible compressibility up to a 60% strain and high stretchability even up to ∼400% in area. Further, in vivo study demonstrates that the hybrid composite gel can be used as a therapeutic for pressure-induced ulcers. The synergy of chemical adhesion and physical chain entanglement via pores provides a way to fabricate a new class of 100% water-based elastomeric materials.

Thermo-osmosis in hydrophilic nanochannels: mechanism and size effect

Understanding thermo-osmosis in nanoscale channels and pores is essential for both theoretical advances of thermally induced mass flow and a wide range of emerging industrial applications. We present a new mechanistic understanding and quantification of thermo-osmosis at nanometric/sub-nanometric length scales and link the outcomes with the non-equilibrium thermodynamics of the phenomenon. The work is focused on thermo-osmosis of water in quartz slit nanochannels, which is analysed by molecular dynamics (MD) simulations of mechano-caloric and thermo-osmotic systems. We investigate the applicability of Onsager reciprocal relation, irreversible thermodynamics, and continuum fluid mechanics at the nanoscale. Further, we analyse the effects of channel size on the thermo-osmosis coefficient, and show, for the first time, that these arise from specific liquid structures dictated by the channel size. The mechanical conditions of the interfacial water under different temperatures are quantified using a continuum approach (pressure tensor distribution) and a discrete approach (body force per molecule) to elucidate the underlying mechanism of thermo-osmosis. The results show that the fluid molecules located in the boundary layers adjacent to the solid surfaces experience a driving force which generates the thermo-osmotic flow. While the findings provide a fundamental understanding of thermo-osmosis, the methods developed provide a route for analysis of the entire class of coupled heat and mass transport phenomena in nanoscale structures.

Tentative identification of key factors determining the hemostatic efficiency of diatom frustule

It is increasingly essential to develop excellent materials for rapid hemorrhage control. Our previous study showed that centric diatoms such as frustules were superior to QuikClot® in hemostasis, however, related studies in pennate diatoms are still scarce. The morphological and physicochemical properties of pennate diatoms are quite different from those of centric diatoms, meaning that significant differences may also be observed from their hemostatic effects. Thus, the hemostasis effects of four pennate diatom frustules (Cocconeiopsis orthoneoides, Navicula avium, Navicula sp., and Pleurosigma indicum) were investigated in this study. Herein, all diatom frustules demonstrated outstanding hemostasis performance. For example, the in vitro coagulation time of C. orthoneoides (100.33 ± 9.5 s) was 32.4% lower than that of QuikClot®. Meanwhile, the hemostatic times of C. orthoneoides in the rat tail amputation and femoral artery models were 82 s and 180 s, respectively, only around one-half and one-third of the QuikClot® values. Moreover, the blood loss amounts of C. orthoneoides in the rat tail amputation and femoral artery model were 73.4% and 61% less than that of QuikClot®. Besides that, diatom frustules also exhibited favorable biocompatibility (hemolysis ratio <5%, MEFs cell viabilities >80%, and no inflammation). To find out the key factors underlying the hemostatic effect of frustules, Pearson correlation analysis was further performed in this study. The results demonstrated that the coagulation reaction time (R) was negatively correlated with the specific surface area and liquid absorbability but positively with the diatom pore diameter. The angle α, indicating the clot formation rate, was negative to the diatom size and pore diameter. Additionally, MA also showed a negative correlation with the BET value. This study can enrich our knowledge about the application potential of diatoms in the field of bleeding control and is helpful in deepening our understanding about the hemostatic mechanism of frustules.

Diatom Bio-Silica and Cellulose Nanofibril for Bio-Triboelectric Nanogenerators and Self-Powered Breath Monitoring Masks

The application of biodegradable and biocompatible materials to triboelectric nanogenerators (TENGs) for harvesting energy from motions of the human body has been attracting significant research interest. Herein, we report diatom bio-silica as a biomaterial additive to enhance the output performance of cellulose nanofibril (CNF)-based TENGs. Diatom frustules (DFs), which are tribopositive bio-silica having hierarchically porous three-dimensional structures and high surface area, have hydrogen bonds with CNFs, resulting in enhanced electron-donating capability and a more roughened surface of the DF-CNF composite film. Hence, DFs were applied to form a tribopositive composite film with CNFs. The DF-CNF biocomposite film is mechanically strong, electron-rich, low-cost, and frictionally rough. The DF-CNF TENG showed an output voltage of 388 V and time-averaged power of 85.5 mW/m² in the contact-separation mode with an efficient contact area of 4.9 cm², and the generated power was sufficient for instantaneous illumination of 102 light-emitting diodes. In addition, a cytotoxicity study and biocompatibility tests on rabbit skin suggested that the DF-CNF composite was biologically safe. Moreover, a practical application of the DF-CNF TENG was examined with a self-powered smart mask for human breathing monitoring. This study not only suggests high output performance of biomaterial-based TENGs but also presents the diverse advantages of the DFs in human body-related applications such as self-powered health monitoring masks, skin-attachable power generators, and tactile feedback systems.

Chitosan/Diatom-Biosilica Aerogel with Controlled Porous Structure for Rapid Hemostasis

Uncontrolled hemorrhage is the main reason of possible preventable death after accidental injury. It is necessary to develop a hemostatic agent with rapid hemostatic performance and good biocompatibility. In this study, a chitosan/diatom-biosilica-based aerogel is developed using dopamine as cross-linker by simple alkaline precipitation and tert-butyl alcohol replacement. The chitosan/diatom-biosilica aerogel exhibits favorable biocompatibility and multiscale hierarchical porous structure (from nanometer to micrometer), which can be controlled by the concentration of tert-butyl alcohol. The displacement of tert-butyl alcohol can keep the porosity of diatom-biosilica in aerogel and give it large surface with efficient water absorption ratio. 30% tert-butyl alcohol replacement of aerogel possesses the largest surface area (74.441 m² g^-1 ), water absorption capacity (316.83 ± 2.04%), and excellent hemostatic performance in vitro blood coagulation (≈70 s). Furthermore, this aerogel exhibits the shortest clotting time and lowest blood loss in rat hemorrhage model. The strong interface effect between aerogel and blood is able to promote erythrocytes aggregation, platelets adhesion, and activation, as well as, activate the intrinsic coagulation pathway to accelerate blood coagulation. All the above results demonstrate that chitosan/diatom-biosilica aerogel has great potential to be a safe and rapid hemostatic material.