Electrospun microfiber membranes embedded with drug-loaded clay nanotubes for sustained antimicrobial protection

Biodegradable polyvinyl alcohol/nano-hydroxyapatite composite membrane enhanced by MXene nanosheets for guided bone regeneration

MXene, as a new category of two-dimensional nanomaterials, exhibits a promising prospect in biomedical applications due to its ultrathin structure and morphology, as well as a range of remarkable properties such as biological, chemical, electronic, and optical properties. In this work, different concentrations of MXene (M) were added to polyvinyl alcohol (PVA, P)/nano-hydroxyapatite (n-HA, H) mixed solution, and series of PVA/n-HA/MXene (PHM) composite membranes were obtained by combining sol-gel and freeze-drying processes. Morphology, chemical composition, surface, and mechanical properties of the prepared PHM membranes were characterized by various techniques. Subsequently, the swelling and degradation performances of the composite membranes were tested by swelling and degradation tests. In addition, in vitro studies like cell adhesion, cytotoxicity, proliferation, osteogenic differentiation, and antibacterial properties of MC3T3-E1 were also evaluated. The results showed that the addition of MXene could apparently improve the composite membranes' physicochemical properties, bioactivity, and osteogenic differentiation. Specially, PHM membrane had the best comprehensive properties when the concentration of MXene was set as 2.0% w/v. In a word, the addition of MXene has a positive effect on improving the mechanical properties, osteogenic induction, and antibacterial properties of PH composite membranes, and the prepared PHM composite membranes possess potential applications for guided bone regeneration.

Highly Cytocompatible Polylactic Acid Based Electrospun Microfibers Loaded with Silver Nanoparticles Generated onto Chestnut Shell Lignin for Targeted Antibacterial Activity and Antioxidant Action

Electrospun (e-spun) fibers are generally regarded as powerful tools for cell growth in tissue regeneration applications, and the possibility of imparting functional properties to these materials represents an increasingly pursued goal. We report herein the preparation of hybrid materials in which an e-spun d,l-polylactic acid matrix, to which chitosan or crystalline nanocellulose was added to improve hydrophilicity, was loaded with different amounts of silver(0) nanoparticles (AgNP) generated onto chestnut shell lignin (CSL) (AgNP@CSL). A solvent-free mechanochemical method was used for efficient (85% of the theoretical value by XRD analysis) Ag(0) production from the reduction of AgNO3 by lignin. For comparison, e-spun fibers containing CSL alone were also prepared. SEM and TEM analyses confirmed the presence of AgNP@CSL (average size 30 nm) on the fibers. Different chemical assays indicated that the AgNP@CSL containing fibers exhibited marked antioxidant properties (EC50 1.6 ± 0.1 mg/mL, DPPH assay), although they were halved with respect to those of the CSL containing fibers, as expected because of the efficient silver ion reduction. All the fibers showed high cytocompatibility toward human mesenchymal stem cells (hMSCs) representative of the self-healing process, and their antibacterial properties were tested against the pathogens Escherichia coli (E. coli), Staphylococcus epidermidis, and Pseudomonas aeruginosa. Finally, competitive surface colonization as simulated by cocultures of hMSC and E. coli showed that AgNP@CSL loaded fibers offered the cells a targeted protection from infection, thus well balancing cytocompatibility and antibacterial properties.

Electrospun polylactic acid nanofibers membrane with copper ion-loaded clay nanotubes for fresh-keeping packaging

The plastics derived from fossil fuels for food packaging results in serious environmental problems. Developing environment-friendly materials for food packaging is urgent and essential. In this study, polylactic acid (PLA) composite nanofibers membranes were prepared with good biocompatibility and antibacterial property. Cu2+ loaded in the natural halloysite nanotubes (HNTs) was used for the antibacterial agent. Cu2+ was loaded in the HNTs and was confirmed by the X-ray photoelectron spectroscopy (XPS). PLA nanofibers with different HNTs-Cu content were continuous nanofibers with the nanoscale range. HNTs-Cu entered into the nanofiber successfully. Thermal analysis results showed composite nanofibers had good thermal stability. Composite nanofiber membranes had the good hydrophobic property. HNTs-Cu improved the mechanical property of composite nanofibers than pure PLA nanofibers. Tensile strength and elasticity modulus of composite nanofibers with 4 % HNTs-Cu content were the most outstanding. L929 cells were cultured on the nanofiber membranes for biocompatibility evaluation. Cell viability of nanofiber membranes was above the 90 %. Cell live/dead staining results showed L929 cells was seldom dead on the nanofiber membranes. PLA/HNTs-Cu nanofiber membranes exhibited excellent antibacterial effects on S. aureus and E. coli. The inhibitory rates against S. aureus and E. coli were 98.31 % and 97.80 % respectively. The fresh-keeping effects of nanofiber membranes were evaluated by the strawberry preservation. Strawberries covered by nanofiber membranes exhibited better appearance, lower weight loss and higher firmness than control, PLA and PLA/HNTs groups. It promised that PLA/HNTs-Cu composite nanofiber membranes have the significant potential application for active food packaging.

Clays and Wound Healing

Aluminosilicates, such as montmorillonite, kaolinite, halloysite, and diatomite, have a uniform bidimensional structure, a high surface-to-volume ratio, inherent stiffness, a dual charge distribution, chemical inertness, biocompatibility, abundant active groups on the surface, such as silanol (Si-OH) and/or aluminol (Al-OH) groups. These compounds are on the list of U.S. Food and Drug Administration-approved active compounds and excipients and are used for various medicinal products, such as wound healing agents, antidiarrheals, and cosmetics. This review summarizes the wound healing mechanisms related to the material characteristics and the chemical components. Numerous wound dressings with different active components and multiple forms have been studied. Then, medicinal mineral resources for use in hemostatic materials can be developed.

Construction of 3D-Printed Sodium Alginate/Chitosan/Halloysite Nanotube Composites as Adsorbents of Methylene Blue

In this study, sodium alginate/chitosan/halloysite nanotube composites were prepared by three-dimensional printing and characterized in terms of morphology, viscosity, thermal properties, and methylene blue (MB) adsorption performance. The high specific surface area and extensively microporous structure of these composites allowed for effective MB removal from wastewater; specifically, a removal efficiency of 80% was obtained after a 60 min treatment at an adsorbent loading of 1 g L-1 and an MB concentration of 80 mg L-1, while the maximum MB adsorption capacity equaled 376.3 mg g-1. Adsorption kinetics and isotherms were well described by quasi-second-order and Langmuir models, respectively. The composites largely retained their adsorption performance after five adsorption-desorption cycles and were concluded to hold great promise for MB removal from wastewater.

Micropatterning of biologically derived surfaces with functional clay nanotubes

Micropatterning of biological surfaces performed via assembly of nano-blocks is an efficient design method for functional materials with complex organic-inorganic architecture. Halloysite clay nanotubes with high aspect ratios and empty lumens have attracted widespread interest for aligned biocompatible composite production. Here, we give our vision of advances in interfacial self-assembly techniques for these natural nanotubes. Highly ordered micropatterns of halloysite, such as coffee rings, regular strips, and concentric circles, can be obtained through high-temperature evaporation-induced self-assembly in a confined space and shear-force brush-induced orientation. Assembly of these clay nanotubes on biological surfaces, including the coating of human or animal hair, wool, and cotton, was generalized with the indication of common features. Halloysite-coated microfibers promise new approaches in cotton and hair dyeing, medical hemostasis, and flame-retardant tissue applications. An interfacial halloysite assembly on oil microdroplets (Pickering emulsion) and its core-shell structure (functionalization with quantum dots) was described in comparison with microfiber nanoclay coatings. In addition to being abundantly available in nature, halloysite is also biosafe, which makes its spontaneous surface micropatterning prospective for high-performance materials, and it is a promising technique with potential for an industrial scale-up.

Addressing Antimicrobial Properties in Guided Tissue/Bone Regeneration Membrane: Enhancing Effectiveness in Periodontitis Treatment

Guided tissue regeneration (GTR) and guided bone regeneration (GBR) are the two surgical techniques generally used for periodontitis disease treatment. These techniques are based on a barrier membrane to direct the growth of new bone and gingival tissue at sites with insufficient volumes or dimensions of bone or gingiva for proper function, esthetics, or prosthetic restoration. Numerous studies have highlighted biocompatibility, space-creation, cell-blocking, bioactivity, and proper handling as essential characteristics of a membrane's performance. Given that bacterial infection is the primary cause of periodontitis, we strongly believe that addressing the antimicrobial properties of these membranes is of utmost importance. Indeed, the absence of effective inhibition of periodontal pathogens has been recognized as a primary factor contributing to the failure of GTR/GBR membranes. Therefore, we suggest considering antimicrobial properties as one of the key factors in the design of GTR/GBR membranes. Antibiotics are potent medications frequently administered systemically to combat microbes and mitigate bacterial infections. Nevertheless, the excessive use of antibiotics has resulted in a surge in bacterial resistance. To overcome this challenge, alternative antibacterial substances have been developed. In this review, we explore the utilization of alternative substances with antimicrobial properties for topical application in membranes. The use of antibacterial nanoparticles, phytochemical compounds, and antimicrobial peptides in this context was investigated. By carefully selecting and integrating antimicrobial agents into GTR/GBR membranes, we can significantly enhance their effectiveness in combating periodontitis. These antibacterial substances not only act as barriers against pathogenic bacteria but also promote the process of periodontal healing.

Bioinspired polysaccharide-based nanocomposite membranes with robust wet mechanical properties for guided bone regeneration

Polysaccharide-based membranes with excellent mechanical properties are highly desired. However, severe mechanical deterioration under wet conditions limits their biomedical applications. Here, inspired by the structural heterogeneity of strong yet hydrated biological materials, we propose a strategy based on heterogeneous crosslink-and-hydration (HCH) of a molecule/nano dual-scale network to fabricate polysaccharide-based nanocomposites with robust wet mechanical properties. The heterogeneity lies in that the crosslink-and-hydration occurs in the molecule-network while the stress-bearing nanofiber-network remains unaffected. As one demonstration, a membrane assembled by bacterial cellulose nanofiber-network and Ca2+-crosslinked and hydrated sodium alginate molecule-network is designed. Studies show that the crosslinked-and-hydrated molecule-network restricts water invasion and boosts stress transfer of the nanofiber-network by serving as interfibrous bridge. Overall, the molecule-network makes the membrane hydrated and flexible; the nanofiber-network as stress-bearing component provides strength and toughness. The HCH dual-scale network featuring a cooperative effect stimulates the design of advanced biomaterials applied under wet conditions such as guided bone regeneration membranes.

Biodegradable and biocompatible alginate/gelatin/MXene composite membrane with efficient osteogenic activity and its application in guided bone regeneration

Guided bone regeneration (GBR) utilizes a barrier membrane to maintain the osteogenic space and promote osseointegration of the implants. Developing a novel biomaterial to meet the mechanical and biological performance requirements of GBR membrane (GBRM) remains a huge challenge. Here, the sodium alginate (SA, S)/gelatin (G)/MXene (M) composite membrane (SGM) was prepared by combining sol-gel and freeze-drying processes. The incorporation of MXene improved the mechanical properties and hydrophilicity of the SA/G (SG) membrane, and also enhanced its cell proliferation and osteogenic differentiation. More importantly, when the concentration of MXene is 0.25%W/V, the SGM composite membrane exhibited the best tensile strength (40 MPa), high swelling rate (1012%), and appropriate degradation rate (40%). Meanwhile, the biological improvements were more significant. Therefore, the appropriate amount addition of MXene has a positive and obvious effect on the improvements of the mechanical properties, biocompatibility, and osteogenic induction of the SG composite membranes. This work provides a more extendable development idea for the application of SGM composite membrane as GBRM.

Polydopamine-Mediated Immunomodulatory Patch for Diabetic Periodontal Tissue Regeneration Assisted by Metformin-ZIF System

An essential challenge in diabetic periodontal regeneration is achieving the transition from a hyperglycemic inflammatory microenvironment to a regenerative one. Here, we describe a polydopamine (PDA)-mediated ultralong silk microfiber (PDA-mSF) and metformin (Met)-loaded zeolitic imidazolate framework (ZIF) incorporated into a silk fibroin/gelatin (SG) patch to promote periodontal soft and hard tissue regeneration by regulating the immunomodulatory microenvironment. The PDA-mSF endows the patch with a reactive oxygen species (ROS)-scavenging ability and anti-inflammatory activity, reducing the inflammatory response by suppressing M1 macrophage polarization. Moreover, PDA improves periodontal ligament reconstruction via its cell affinity. Sustained release of Met from the Met-ZIF system confers the patch with antiaging and immunomodulatory abilities by activating M2 macrophage polarization to secrete osteogenesis-related cytokines, while release of Zn2+ also promotes bone regeneration. Consequently, the Met-ZIF system creates a favorable microenvironment for periodontal tissue regeneration. These features synergistically accelerate diabetic periodontal bone and ligament regeneration. Thus, our findings offer a potential therapeutic strategy for hard and soft tissue regeneration in diabetic periodontitis.

Nanofiber matrix formulations for the delivery of Exendin-4 for tendon regeneration: In vitro and in vivo assessment

Tendon and ligament injuries are the most common musculoskeletal injuries, which not only impact the quality of life but result in a massive economic burden. Surgical interventions for tendon/ligament injuries utilize biological and/or engineered grafts to reconstruct damaged tissue, but these have limitations. Engineered matrices confer superior physicochemical properties over biological grafts but lack desirable bioactivity to promote tissue healing. While incorporating drugs can enhance bioactivity, large matrix surface areas and hydrophobicity can lead to uncontrolled burst release and/or incomplete release due to binding. To overcome these limitations, we evaluated the delivery of a peptide growth factor (exendin-4; Ex-4) using an enhanced nanofiber matrix in a tendon injury model. To overcome drug surface binding due to matrix hydrophobicity of poly(caprolactone) (PCL)-which would be expected to enhance cell-material interactions-we blended PCL and cellulose acetate (CA) and electrospun nanofiber matrices with fiber diameters ranging from 600 to 1000 nm. To avoid burst release and protect the drug, we encapsulated Ex-4 in the open lumen of halloysite nanotubes (HNTs), sealed the HNT tube endings with a polymer blend, and mixed Ex-4-loaded HNTs into the polymer mixture before electrospinning. This reduced burst release from ∼75% to ∼40%, but did not alter matrix morphology, fiber diameter, or tensile properties. We evaluated the bioactivity of the Ex-4 nanofiber formulation by culturing human mesenchymal stem cells (hMSCs) on matrix surfaces for 21 days and measuring tenogenic differentiation, compared with nanofiber matrices in basal media alone. Strikingly, we observed that Ex-4 nanofiber matrices accelerated the hMSC proliferation rate and elevated levels of sulfated glycosaminoglycan, tendon-related genes (Scx, Mkx, and Tnmd), and ECM-related genes (Col-I, Col-III, and Dcn), compared to control. We then assessed the safety and efficacy of Ex-4 nanofiber matrices in a full-thickness rat Achilles tendon defect with histology, marker expression, functional walking track analysis, and mechanical testing. Our analysis confirmed that Ex-4 nanofiber matrices enhanced tendon healing and reduced fibrocartilage formation versus nanofiber matrices alone. These findings implicate Ex-4 as a potentially valuable tool for tendon tissue engineering.

Therapeutic Agent-Loaded Fibrous Scaffolds for Biomedical Applications

Tissue engineering is a sophisticated field that involves the integration of various disciplines, such as clinical medicine, material science, and life science, to repair or regenerate damaged tissues and organs. To achieve the successful regeneration of damaged or diseased tissues, it is necessary to fabricate biomimetic scaffolds that provide structural support to the surrounding cells and tissues. Fibrous scaffolds loaded with therapeutic agents have shown considerable potential in tissue engineering. In this comprehensive review, we examine various methods for fabricating bioactive molecule-loaded fibrous scaffolds, including preparation methods for fibrous scaffolds and drug-loading techniques. Additionally, we delved into the recent biomedical applications of these scaffolds, such as tissue regeneration, inhibition of tumor recurrence, and immunomodulation. The aim of this review is to discuss the latest research trends in fibrous scaffold manufacturing methods, materials, drug-loading methods with parameter information, and therapeutic applications with the goal of contributing to the development of new technologies or improvements to existing ones.

Underestimated microbial infection of resorbable membranes on guided regeneration

Barrier membranes are critical in creating tissuecompartmentalization for guided tissue (GTR) and bone regeneration (GBR) therapies. More recently, resorbable membranes have been widely used for tissue and bone regeneration due to their improved properties and the dispensable re-entry surgery for membrane removal. However, in cases with membrane exposure, this may lead to microbial contamination that will compromise the integrity of the membrane, surrounding tissue, and bone regeneration, resulting in treatment failure. Although the microbial infection can negatively influence the clinical outcomes of regenerative therapy, such as GBR and GTR, there is a lack of clinical investigations in this field, especially concerning the microbial colonization of different types of membranes. Importantly, a deeper understanding of the mechanisms of biofilm growth and composition and pathogenesis on exposed membranes is still missing, explaining the mechanisms by which bone regeneration is reduced during membrane exposure. This scoping review comprehensively screened and discussed the current in vivo evidence and possible new perspectives on the microbial contamination of resorbable membranes. Results from eligible in vivo studies suggested that different bacterial species colonized exposed membranes according to their composition (collagen, expanded polytetrafluoroethylene (non-resorbable), and polylactic acid), but in all cases, it negatively affected the attachment level and amount of bone gain. However, limited models and techniques have evaluated the newly developed materials, and evidence is scarce. Finally, new approaches to enhance the antimicrobial effect should consider changing the membrane surface or incorporating long-term released antimicrobials in an effort to achieve better clinical success.

Phase-change composite filled natural nanotubes in hydrogel promote wound healing under photothermally triggered drug release

It is of great importance to treat a bacterial-infected wound by a smart dressing capable of delivering antibiotics in a smart manner without causing drug resistance. The construction of smart release nanocontainers responsive to near-infrared (NIR) laser irradiation in an on-demand and stepwise way is a promising strategy for avoiding the emergence of multidrug-resistant bacteria. Here, we develop a hydrogel composite made of alginate and nanotubes with an efficient NIR-triggered release of rifampicin and outstanding antibacterial ability. This composite hydrogel is prepared through co-encapsulating antibacterial drug (rifampicin), NIR-absorbing dye (indocyanine green), and phase-change materials (a eutectic mixture of fatty acids) into halloysite nanotubes, followed by incorporation into alginate hydrogels, allowing the in-situ gelation at room temperature and maintaining the integrity of drug-loaded nanotubes. Among them, the eutectic mixture with a melting point of 39 °C serves as the biocompatible phase-change material to facilitate the NIR-triggered drug release. The resultant phase-change material gated-nanotubes exhibit a prominent photothermal efficiency with multistep drug release under laser irradiation. In an in vitro assay, composite hydrogel provides good antibacterial potency against Staphylococcus aureus, one of the most prevalent microorganisms of dangerous gas gangrene. A bacterial-infected rat full-thickness wound model demonstrates that the NIR-responsive composite hydrogel inhibits the bacteria colonization and suppresses the inflammatory response caused by bacteria, promoting angiogenesis and collagen deposition to accelerate wound regeneration. The NIR-responsive composite hydrogel has a great potential as an antibacterial wound dressing functionalized with controlled multistep treatment of the infected sites.

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Phase change material-gated nanocontainer exhibits an efficient NIR-triggered release of drugs.

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Photothermal-responsive hydrogel shows efficient antibacterial properties through the NIR-responsive step-wise antibacterial drug release.

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In vivo, photothermal-responsive hydrogel inhibits bacterial proliferation and effectively suppress the inflammatory response caused by bacteria, thus accelerating bacteria-infected wound regeneration.

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Various types of drugs and biological effectors can be loaded in the nanotubes while the hydrogel matrix can also be regulated to achieve multiple healing functions.

Combining a Density Gradient of Biomacromolecular Nanoparticles with Biological Effectors in an Electrospun Fiber-Based Nerve Guidance Conduit to Promote Peripheral Nerve Repair

Peripheral nerve injury is a serious medical problem with limited surgical and clinical treatment options. It is of great significance to integrate multiple guidance cues in one platform of nerve guidance conduits (NGCs) to promote axonal elongation and functional recovery. Here, a multi-functional NGC is constructed to promote nerve regeneration by combining ordered topological structure, density gradient of biomacromolecular nanoparticles, and controlled delivery of biological effectors to provide the topographical, haptotactic, and biological cues, respectively. On the surface of aligned polycaprolactone nanofibers, a density gradient of bioactive nanoparticles capable of delivering recombinant human acidic fibroblast growth factor is deposited. On the graded scaffold, the proliferation of Schwann cells is promoted, and the directional extension of neurites from both PC12 cells and dorsal root ganglions is improved in the direction of increasing particle density. After being implanted in vivo for 6 and 12 weeks to repair a 10-mm rat sciatic nerve defect, the NGC promotes axonal elongation and remyelination, achieving the regeneration of the nerve not only in anatomical structure but also in functional recovery. Taken together, the NGC provides a favorable microenvironment for peripheral nerve regeneration and holds great promise for realizing nerve repair with an efficacy close to autograft.

Functionally modified halloysite nanotubes for personalized bioapplications

Halloysite nanotubes (HNTs) are naturally aluminosilicate clay minerals that have the benefits of large surface areas, high mechanical properties, easy functionalization, and high biocompatibility, HNTs have been developed as multifunctional nanoplatforms for various bioapplications. Although some reviews have summarized the properties and bioapplications of HNTs, it remains unclear how to functionalize the modifications of HNTs for their personalized bioapplications. In this review, based on the physicochemical properties of HNTs, we summarized the methods of functionalized modifications (surface modification and structure modification) on HNTs. Also, we highlighted their personalized bioapplications (anti-bacterial, anti-inflammatory, wound healing, cancer theranostics, bone regenerative, and biosensing) by stressing on the main roles of HNTs. Finally, we provide perspectives on the future of functionalized modifications of HNTs for docking specific biological applications.

Periosteum-Inspired Membranes Integrated with Bioactive Magnesium Oxychloride Ceramic Nanoneedles for Guided Bone Regeneration

Guided bone regeneration (GBR) technique using a barrier membrane holds great potential to allow the single-stage reconstruction of critical-sized bone defects. Here, bioactive nanoneedle-like magnesium oxychloride ceramics (MOCs) are synthesized and recruited as an osteoinductive factor within a polycaprolactone-gelatin A (PCL-GelA) membranous matrix to generate a periosteum-mimicking biphasic GBR membrane (PCL-GelA/MOC) to accelerate calvarial defect repair. The PCL-GelA/MOC membrane acts as a shield for defect areas and a reservoir of osteoinductive molecules, which provides a favorable microenvironment for supporting cell proliferation, infiltration, and differentiation. This membrane leads to accelerated osteogenesis and angiogenesis, effectual defect bridging, and significantly enhanced bone regeneration when applied to a 5 mm sized rat calvarial defect. This makes this innovative and multifunctional GBR membrane a suitable candidate for clinical applications with promising curative efficacy.

A Bilayer Membrane Doped with Struvite Nanowires for Guided Bone Regeneration

Guided bone regeneration (GBR) therapy demonstrates a prominent curative effect on the management of craniomaxillofacial (CMF) bone defects. In this study, a GBR membrane consisting of a microporous layer and a struvite-nanowire-doped fibrous layer is constructed via non-solvent induced phase separation, followed by an electrospinning procedure to treat critical-sized calvarial defects. The microporous layer shows selective permeability for excluding the rapid-growing non-osteogenic tissues and potential wound stabilization. The nanowire-like struvite is synthesized as the deliverable therapeutic agent within the fibrous layer to facilitate bone regeneration. Such a membrane displays a well-developed heterogeneous architecture, satisfactory mechanical performance, and long-lasting characteristics. The in vitro biological evaluation reveals that apart from being a strong barrier, the bilayer struvite-laden membrane can actively promote cellular adhesion, proliferation, and osteogenic differentiation. Consequently, the multifunctional struvite-doped membranes are applied to treat 5 mm-sized bilateral calvarial defects in rats, resulting in overall improved healing outcomes compared with the untreated or the struvite-free membrane-treated group, which is characterized by enhanced osteogenesis and significantly increased new bone formation. The encouraging preclinical results reveal the great potential of the bilayer struvite-doped membrane as a clinical GBR device for augmenting large-area CMF bone reconstruction.

Fabrication and Evaluation of Electrospun Silk Fibroin/Halloysite Nanotube Biomaterials for Soft Tissue Regeneration

The production of nanofibrous materials for soft tissue repair that resemble extracellular matrices (ECMs) is challenging. Electrospinning uniquely produces scaffolds resembling the ultrastructure of natural ECMs. Herein, electrospinning was used to fabricate Bombyx mori silk fibroin (SF) and SF/halloysite nanotube (HNT) composite scaffolds. Different HNT loadings were examined, but 1 wt% HNTs enhanced scaffold hydrophilicity and water uptake capacity without loss of mechanical strength. The inclusion of 1 wt% HNTs in SF scaffolds also increased the scaffold’s thermal stability without altering the molecular structure of the SF, as revealed by thermogravimetric analyses and Fourier transform infrared spectroscopy (FTIR), respectively. SF/HNT 1 wt% composite scaffolds better supported the viability and spreading of 3T3 fibroblasts and the differentiation of C2C12 myoblasts into aligned myotubes. These scaffolds coated with decellularised ECM from 3T3 cells or primary human dermal fibroblasts (HDFs) supported the growth of primary human keratinocytes. However, SF/HNT 1 wt% composite scaffolds with HDF-derived ECM provided the best microenvironment, as on these, keratinocytes formed intact monolayers with an undifferentiated, basal cell phenotype. Our data indicate the merits of SF/HNT 1 wt% composite scaffolds for applications in soft tissue repair and the expansion of primary human keratinocytes for skin regeneration.

Triblock Copolymer Compatibilizers for Enhancing the Mechanical Properties of a Renewable Bio-Polymer

Poly(lactic acid) (PLA) is an emerging plastic that has insufficient properties (e.g., it is too brittle) for widespread commercial use. Previous research results have shown that the strength and toughness of basalt fiber reinforced PLA composites (PLA/BF) still need to be improved. To address this limitation, this study aimed to obtain an effective compatibilizer for PLA/BF. Melt-blending of poly(butylene adipate-co-terephthalate) (PBAT) with PLA in the presence of 4,4′-methylene diphenyl diisocyanate (MDI: 0.5 wt% of the total resin) afforded PLA/PBAT-MDI triblock copolymers. The triblock copolymers were melt-blended to improve the interfacial adhesion of PLA/BF and thus obtain excellent performance of the PLA-ternary polymers. This work presents the first investigation on the effects of PLA/PBAT-MDI triblock copolymers as compatibilizers for PLA/BF blends. The resultant mechanics, the morphology, interface, crystallinity, and thermal stability of the PLA-bio polymers were comprehensively examined via standard characterization techniques. The crystallinity of the PLA-ternary polymers was as high as 43.6%, 1.44× that of PLA/BF, and 163.5% higher than that of pure PLA. The stored energy of the PLA-ternary polymers reached 20,306.2 MPa, 5.5× than that of PLA/BF, and 18.6× of pure PLA. Moreover, the fatigue life of the PLA-ternary polymers was substantially improved, 5.85× than that of PLA/PBAT-MDI triblock copolymers. Thus, the PLA/PBAT-MDI triblock copolymers are compatibilizers that improve the mechanical properties of PLA/BF.

Molecular imaging nanoprobes for theranostic applications

As a non-invasive imaging monitoring method, molecular imaging can provide the location and expression level of disease signature biomolecules in vivo, leading to early diagnosis of relevant diseases, improved treatment strategies, and accurate assessment of treating efficacy. In recent years, a variety of nanosized imaging probes have been developed and intensively investigated in fundamental/translational research and clinical practice. Meanwhile, as an interdisciplinary discipline, this field combines many subjects of chemistry, medicine, biology, radiology, and material science, etc. The successful molecular imaging not only requires advanced imaging equipment, but also the synthesis of efficient imaging probes. However, limited summary has been reported for recent advances of nanoprobes. In this paper, we summarized the recent progress of three common and main types of nanosized molecular imaging probes, including ultrasound (US) imaging nanoprobes, magnetic resonance imaging (MRI) nanoprobes, and computed tomography (CT) imaging nanoprobes. The applications of molecular imaging nanoprobes were discussed in details. Finally, we provided an outlook on the development of next generation molecular imaging nanoprobes.

Integrating Inflammation-Responsive Prodrug with Electrospun Nanofibers for Anti-Inflammation Application

Chronic inflammation plays a side effect on tissue regeneration, greatly inhibiting the repair or regeneration of tissues. Conventional local delivery of anti-inflammation drugs through physical encapsulation into carriers face the challenges of uncontrolled release. The construction of an inflammation-responsive prodrug to release anti-inflammation drugs depending on the occurrence of inflammation to regulate chronic inflammation is of high need. Here, we construct nanofiber-based scaffolds to regulate the inflammation response of chronic inflammation during tissue regeneration. An inflammation-sensitive prodrug is synthesized by free radical polymerization of the indomethacin-containing precursor, which is prepared by the esterification of N-(2-hydroxyethyl) acrylamide with the anti-inflammation drug indomethacin. Then, anti-inflammation scaffolds are constructed by loading the prodrug in poly(ε-caprolactone)/gelatin electrospun nanofibers. Cholesterol esterase, mimicking the inflammation environment, is adopted to catalyze the hydrolysis of the ester bonds, both in the prodrug and the nanofibers matrix, leading to the generation of indomethacin and the subsequent release to the surrounding. In contrast, only a minor amount of the drug is released from the scaffold, just based on the mechanism of hydrolysis in the absence of cholesterol esterase. Furthermore, the inflammation-responsive nanofiber scaffold can effectively inhibit the cytokines secreted from RAW264.7 macrophage cells induced by lipopolysaccharide in vitro studies, highlighting the great potential of these electrospun nanofiber scaffolds to be applied for regulating the chronic inflammation in tissue regeneration.

Advances in Modification Methods Based on Biodegradable Membranes in Guided Bone/Tissue Regeneration: A Review

Guided tissue/bone regeneration (GTR/GBR) is commonly applied in dentistry to aid in the regeneration of bone/tissue at a defective location, where the assistive material eventually degrades to be substituted with newly produced tissue. Membranes separate the rapidly propagating soft tissue from the slow-growing bone tissue for optimal tissue regeneration results. A broad membrane exposure area, biocompatibility, hardness, ductility, cell occlusion, membrane void ratio, tissue integration, and clinical manageability are essential functional properties of a GTR/GBR membrane, although no single modern membrane conforms to all of the necessary characteristics. This review considers ongoing bone/tissue regeneration engineering research and the GTR/GBR materials described in this review fulfill all of the basic ISO requirements for human use, as determined through risk analysis and rigorous testing. Novel modified materials are in the early stages of development and could be classified as synthetic polymer membranes, biological extraction synthetic polymer membranes, or metal membranes. Cell attachment, proliferation, and subsequent tissue development are influenced by the physical features of GTR/GBR membrane materials, including pore size, porosity, and mechanical strength. According to the latest advances, key attributes of nanofillers introduced into a polymer matrix include suitable surface area, better mechanical capacity, and stability, which enhances cell adhesion, proliferation, and differentiation. Therefore, it is essential to construct a bionic membrane that satisfies the requirements for the mechanical barrier, the degradation rate, osteogenesis, and clinical operability.

Covalent Organic Framework-Incorporated Nanofibrous Membrane as an Intelligent Platform for Wound Dressing

Covalent organic frameworks (COFs) possess fascinating features that have sparked increasing interest as drug carriers in biomedical applications. However, the promising properties of COFs in wound healing have rarely been reported. Herein, a facile one-pot method is reported to prepare a curcumin-loaded COF (CUR@COF) by the condensation reaction and the Schiff base reaction and to further incorporate CUR@COF into polycaprolactone (PCL) nanofibrous membranes (CUR@COF/PCL NFMs) through electrospinning to develop a pH-triggered drug release platform for wound dressing. CUR@COF has a high CUR loading capacity of 27.68%, and CUR@COF/PCL NFMs exhibit increased thermal stability, improved mechanical properties, good biocompatibility, and enhanced antibacterial and antioxidant activities. More importantly, CUR@COF-based membranes show a pH-responsive CUR release profile by protonation under acidic conditions, suggesting the promotion of CUR release from membranes under an acidic extracellular microenvironment. The histopathological analysis and immunofluorescence staining of an in vivo skin defect model indicate that CUR@COF/PCL NFMs can accelerate wound healing and skin regeneration by reducing the expression of inflammatory factors (TNF-α) and enhancing the expression of angiogenesis (VEGF). This work provides a new strategy by employing COF-based drug-encapsulated nanocomposites for wound dressing applications.

Antibiotic-Loaded Polymeric Barrier Membranes for Guided Bone/Tissue Regeneration: A Mini-Review

Polymeric membranes are frequently used for bone regeneration in oral and periodontal surgery. Polymers provide adequate mechanical properties (i.e., Young’s modulus) to support oral function and also pose some porosity with interconnectivity to permit for cell proliferation and migration. Bacterial contamination of the membrane is an event that may lead to infection at the bone site, hindering the clinical outcomes of the regeneration procedure. Therefore, polymeric membranes have been proposed as carriers for local antibiotic therapy. A literature search was performed for papers, including peer-reviewed publications. Among the different membranes, collagen is the most employed biomaterial. Collagen membranes and expanded polytetrafluoroethylene loaded with tetracyclines, and polycaprolactone with metronidazole are the combinations that have been assayed the most. Antibiotic liberation is produced in two phases. A first burst release is sometimes followed by a sustained liberation lasting from 7 to 28 days. All tested combinations of membranes and antibiotics provoke an antibacterial effect, but most of the time, they were measured against single bacteria cultures and usually non-specific pathogenic bacteria were employed, limiting the clinical relevance of the attained results. The majority of the studies on animal models state a beneficial effect of these antibiotic functionalized membranes, but human clinical assays are scarce and controversial.

Antibacterial Electrospun Polycaprolactone Nanofibers Reinforced by Halloysite Nanotubes for Tissue Engineering

Due to its slow degradation rate, polycaprolactone (PCL) is frequently used in biomedical applications. This study deals with the development of antibacterial nanofibers based on PCL and halloysite nanotubes (HNTs). Thanks to a combination with HNTs, the prepared nanofibers can be used as low-cost nanocontainers for the encapsulation of a wide variety of substances, including drugs, enzymes, and DNA. In our work, HNTs were used as a nanocarrier for erythromycin (ERY) as a model antibacterial active compound with a wide range of antibacterial activity. Nanofibers based on PCL and HNT/ERY were prepared by electrospinning. The antibacterial activity was evaluated as a sterile zone of inhibition around the PCL nanofibers containing 7.0 wt.% HNT/ERY. The morphology was observed with SEM and TEM. The efficiency of HNT/ERY loading was evaluated with thermogravimetric analysis. It was found that the nanofibers exhibited outstanding antibacterial properties and inhibited both Gram- (Escherichia coli) and Gram+ (Staphylococcus aureus) bacteria. Moreover, a significant enhancement of mechanical properties was achieved. The potential uses of antibacterial, environmentally friendly, nontoxic, biodegradable PCL/HNT/ERY nanofiber materials are mainly in tissue engineering, wound healing, the prevention of bacterial infections, and other biomedical applications.

Metronidazole Topically Immobilized Electrospun Nanofibrous Scaffold: Novel Secondary Intention Wound Healing Accelerator

The process of secondary intention wound healing includes long repair and healing time. Electrospun nanofibrous scaffolds have shown potential for wound dressing. Biopolymers have gained much attention due to their remarkable characteristics such as biodegradability, biocompatibility, non-immunogenicity and nontoxicity. This study anticipated to develop a new composite metronidazole (MTZ) immobilized nanofibrous scaffold based on poly (3-hydroxy butyrate) (PHB) and Gelatin (Gel) to be utilized as a novel secondary intention wound healing accelerator. Herein, PHB and Gel were mixed together at different weight ratios to prepare polymer solutions with final concentration of (7%), loaded with two different concentrations 5% (Z₁) and 10% (Z₂) of MTZ. Nanofibrous scaffolds were obtained by manipulating electrospinning technique. The properties of MTZ immobilized PHB/Gel nanofibrous scaffold were evaluated (SEM, FTIR, TGA, water uptake, contact angle, porosity, mechanical properties and antibacterial activity). Additionally, in vitro cytocompatibility of the obtained nanofibrous scaffolds were assessed by using the cell counting kit-8 (CCK-8 assay). Moreover, in vivo wound healing experiments revealed that the prepared nanofibrous scaffold highly augmented the transforming growth factor (TGF-β) signaling pathway, moderately suppressed the pro-inflammatory cytokine (IL-6). These results indicate that MTZ immobilized PHB/Gel nanofibrous scaffold significantly boost accelerating secondary intention wound healing.

Finding the Perfect Membrane: Current Knowledge on Barrier Membranes in Regenerative Procedures: A Descriptive Review

Guided tissue regeneration (GTR) and guided bone regeneration (GBR) became common procedures in the corrective phase of periodontal treatment. In order to obtain good quality tissue neo-formation, most techniques require the use of a membrane that will act as a barrier, having as a main purpose the blocking of cell invasion from the gingival epithelium and connective tissue into the newly formed bone structure. Different techniques and materials have been developed, aiming to obtain the perfect barrier membrane. The membranes can be divided according to the biodegradability of the base material into absorbable membranes and non-absorbable membranes. The use of absorbable membranes is extremely widespread due to their advantages, but in clinical situations of significant tissue loss, the use of non-absorbable membranes is often still preferred. This descriptive review presents a synthesis of the types of barrier membranes available and their characteristics, as well as future trends in the development of barrier membranes along with some allergological aspects of membrane use.

Finding the Perfect Membrane: Current Knowledge on Barrier Membranes in Regenerative Procedures: A Descriptive Review

Guided tissue regeneration (GTR) and guided bone regeneration (GBR) became common procedures in the corrective phase of periodontal treatment. In order to obtain good quality tissue neo-formation, most techniques require the use of a membrane that will act as a barrier, having as a main purpose the blocking of cell invasion from the gingival epithelium and connective tissue into the newly formed bone structure. Different techniques and materials have been developed, aiming to obtain the perfect barrier membrane. The membranes can be divided according to the biodegradability of the base material into absorbable membranes and non-absorbable membranes. The use of absorbable membranes is extremely widespread due to their advantages, but in clinical situations of significant tissue loss, the use of non-absorbable membranes is often still preferred. This descriptive review presents a synthesis of the types of barrier membranes available and their characteristics, as well as future trends in the development of barrier membranes along with some allergological aspects of membrane use.

The fabrication of halloysite nanotube-based multicomponent hydrogel scaffolds for bone healing

Bone tissue engineering, as an alternative for common available therapeutic approaches, has been developed to focus on reconstructing of the missing tissues and restoring their functionality. In this work, three-dimensional (3D) nanocomposite scaffolds of polycaprolactone-polyethylene glycol-polycaprolactone/gelatin (PCEC/Gel) were prepared by freeze-drying method. Biocompatible nanohydroxyapatite (nHA), iron oxide nanoparticle (Fe₃O₄) and halloysite nanotube (HNT) powders were added to the polymer matrix aiming to combine the osteogenic activity of nHA or Fe₃O₄ with high mechanical strength of HNT. The scanning electron microscope (SEM) methods was utilized to characterize the nanotube morphology of HNT as well as nanoparticles of Fe₃O₄ and nHA. Prepared scaffolds were characterized via Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), and SEM methods. In addition, the physical behavior of scaffolds was evaluated to explore the influence of HNT on the physicochemical properties of composites. Cell viability and attachment were investigated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assay and SEM on human dental pulp-derived mesenchymal stem cells (h-DPSCs) in-vitro. Cell proliferation was observed without any cytotoxicity effect on h-DPSCs for all examined scaffolds. Alizarin red (ARS) and alkaline phosphatase (ALP) staining were carried out to determine the osteoconductivity of scaffolds. The data demonstrated that all PCEC/Gel/HNT hydrogel scaffolds supported osteoblast differentiation of hDPSCs with moderate effects on cell proliferation. Moreover, PCEC/Gel/HNT/nHA with proper mechanical strength showed better biological activity compared to PCEC/Gel/HNT/Fe₃O₄ and PCEC/Gel/HNT scaffolds. Therefore, this study suggested that with proper fillers content, PCEC/Gel/HNT nanocomposite hydrogels alone or in a complex with nHA, Fe₃O₄ could be a suitable candidate for hard tissue regeneration.

Electrospun Nanofibers for Bone Regeneration: From Biomimetic Composition, Structure to Function

In recent years, a variety of novel materials and processing technologies have been developed to prepare tissue engineering scaffolds for bone defect repair. Among them, nanofibers fabricated via electrospinning technology...

Physical and biological properties of electrospun poly(d,l-lactide)/nanoclay and poly(d,l-lactide)/nanosilica nanofibrous scaffold for bone tissue engineering

Electrospun scaffolds exhibiting high physical performances with the ability to support cell attachment and proliferation are attracting more and more scientific interest for tissue engineering applications. The inclusion of inorganic nanoparticles such as nanosilica and nanoclay into electrospun biopolymeric matrices can meet these challenging requirements. The silica and clay incorporation into polymeric nanofibers has been reported to enhance and improve the mechanical properties as well as the osteogenic properties of the scaffolds. In this work, for the first time, the physical and biological properties of polylactic acid (PLA) electrospun mats filled with different concentrations of nanosilica and nanoclay were evaluated and compared. The inclusion of the particles was evaluated through morphological investigations and Fourier transform infrared spectroscopy. The morphology of nanofibers was differently affected by the amount and kind of fillers and it was correlated to the viscosity of the polymeric suspensions. The wettability of the scaffolds, evaluated through wet contact angle measurements, slightly increased for both the nanocomposites. The crystallinity of the systems was investigated by differential scanning calorimetry highlighting the nucleating action of both nanosilica and nanoclay on PLA. Scaffolds were mechanically characterized with tensile tests to evaluate the reinforcing action of the fillers. Finally, cell culture assays with pre-osteoblastic cells were conducted on a selected composite scaffold in order to compare the cell proliferation and morphology with that of neat PLA scaffolds. Based on the results, we can convince that nanosilica and nanoclay can be both considered great potential fillers for electrospun systems engineered for bone tissue regeneration.

Robust hemostatic bandages based on nanoclay electrospun membranes

Death from acute hemorrhage is a major problem in military conflicts, traffic accidents, and surgical procedures, et al. Achieving rapid effective hemostasis for pre-hospital care is essential to save lives in massive bleeding. An ideal hemostasis material should have those features such as safe, efficient, convenient, economical, which remains challenging and most of them cannot be achieved at the same time. In this work, we report a rapid effective nanoclay-based hemostatic membranes with nanoclay particles incorporate into polyvinylpyrrolidone (PVP) electrospun fibers. The nanoclay electrospun membrane (NEM) with 60 wt% kaolinite (KEM1.5) shows better and faster hemostatic performance in vitro and in vivo with good biocompatibility compared with most other NEMs and clay-based hemostats, benefiting from its enriched hemostatic functional sites, robust fluffy framework, and hydrophilic surface. The robust hemostatic bandages based on nanoclay electrospun membrane is an effective candidate hemostat in practical application.

Rapid, easy and effective haemostasis is needed to reduce the loss of life from traumatic haemorrhage. Here, the authors report on the creation of polymer-nanoclay electrospun membranes and demonstrate haemostatic effects showing superior effects to other clay based haemostats.

Biofunctionalization of electrospun fiber membranes by LbL-collagen/chondroitin sulfate nanocoating followed by mineralization for bone regeneration

It is of great significance to develop osteoinductive artificial scaffold for bone repair and regeneration. We constructed a biomimetic apatite interface on electrospun polycaprolactone fibers by combining layer-by-layer (LbL) nanocoating with mineralization to fabricate an osteoinductive artificial scaffold. After polydopamine modification, cationic type-І collagen and anionic chondroitin sulfate were sequentially adsorbed on the fiber surface. The fibers coated with the multilayer components served as the precursor matrix to induce apatite deposition. By adjusting the number of the layers and duration of mineralization, the nanoscale morphology of composite fibers was optimized. When ten bilayers of the collagen and chondroitin sulfate were deposited onto the fibers followed by one day-mineralization, the obtained polycaprolactone-apatite composite scaffolds significantly promoted the adhesion, proliferation, and osteogenic differentiation of MC3T3-E1 cells. In a subcutaneous implantation in mice, this composite fiber membrane enhanced in vivo ectopic osteogenesis. Our nano-architectural scaffolds were able to mimic the composition and structure of the bone matrix to a certain extent, holding great potential for bone repair and regeneration.

Photocatalytic Nanofiber Membranes for the Degradation of Micropollutants and Their Antimicrobial Activity: Recent Advances and Future Prospects

This review paper systematically evaluates current progress on the development and performance of photocatalytic nanofiber membranes often used in the removal of micropollutants from water systems. It is demonstrated that nanofiber membranes serve as excellent support materials for photocatalytic nanoparticles, leading to nanofiber membranes with enhanced optical properties, as well as improved recovery, recyclability, and reusability. The tremendous performance of photocatalytic membranes is attributed to the photogenerated reactive oxygen species such as hydroxyl radicals, singlet oxygen, and superoxide anion radicals introduced by catalytic nanoparticles such as TiO₂ and ZnO upon light irradiation. Hydroxyl radicals are the most reactive species responsible for most of the photodegradation processes of these unwanted pollutants. The review also demonstrates that self-cleaning and antimicrobial nanofiber membranes are useful in the removal of microbial species in water. These unique materials are also applicable in other fields such as wound dressing since the membrane allows for oxygen flow in wounds to heal while antimicrobial agents protect wounds against infections. It is demonstrated that antimicrobial activities against bacteria and photocatalytic degradation of micropollutants significantly reduce membrane fouling. Therefore, the review demonstrates that electrospun photocatalytic nanofiber membranes with antimicrobial activity form efficient cost-effective multifunctional composite materials for the removal of unwanted species in water and for use in various other applications such as filtration, adsorption and electrocatalysis.

Polymer-Based Carriers in Dental Local Healing-Review and Future Challenges

Polymers in drug formulation technology and the engineering of biomaterials for the treatment of oral diseases constitute a group of excipients that often possess additional properties in addition to their primary function, i.e., biological activity, sensitivity to stimuli, mucoadhesive properties, improved penetration of the active pharmaceutical ingredient (API) across biological barriers, and effects on wound healing or gingival and bone tissue regeneration. Through the use of multifunctional polymers, it has become possible to design carriers and materials tailored to the specific conditions and site of application, to deliver the active substance directly to the affected tissue, including intra-periodontal pocket delivery, and to release the active substance in a timed manner, allowing for the improvement of the form of application and further development of therapeutic strategies. The scope of this review is polymeric drug carriers and materials developed from selected multifunctional groups of natural, semi-synthetic, and synthetic polymers for topical therapeutic applications. Moreover, the characteristics of the topical application and the needs for the properties of carriers for topical administration of an active substance in the treatment of oral diseases are presented to more understand the difficulties associated with the design of optimal active substance carriers and materials for the treatment of lesions located in the oral cavity.

Fabrication of multifunctional mucoadhesive buccal patch for drug delivery applications

Mucoadhesive buccal patch is a promising dosage form for a successful oral drug delivery, which provides unique advantages for various applications such as treatment of periodontal disease and postdental surgery disorders. The aim of this study is to synthesize a novel multifunctional mucoadhesive buccal patch in a multilayer reservoir design for therapeutic applications. The patches were fabricated through simultaneous electrospinning of chitosan/poly(vinylalcohol) (PVA)/ibuprofen and electrospraying of phenylalanine amino acid nanotubes (PhNTs) containing metronidazole into the electrospun mats through a layer-by-layer process. An electrospun poly(caprolactone) (PCL) was used as an impermeable backing layer to protect the mucoadhesive component from tongue movement and drug loss. Buccal patches were characterized using scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM) and also evaluated in terms of physicomechanical parameters such as pH, weight, thickness, tensile strength, folding endurance, and mucoadhesive properties. The swelling index of the patches was examined with respect to the PVA/chitosan ratio. The effect of genipin addition to the electrospinning solution was also studied on mucoadhesive and swelling properties. The cell viability of buccal patches was assessed by methylthiazolydiphenyl-tetrazolium bromide test on L929 fibroblast cell line. The patch with an optimal amount of mucoadhesive polymers (PVA/chitosan 80:20) and crosslinking agent (0.05 g) indicated an ideal hemostatic activity along with antibacterial properties against Streptococcus mutans bacteria. The synthesized multifunctional mucoadhesive patch with a novel composition and design has a great potential for oral therapeutic applications.

Diatom-inspired 2D nitric oxide releasing anti-infective porous nanofrustules

Two-dimensional (2D) nanomaterials (NM) have emerged as promising platforms for antibacterial applications. However, the inherent "flatness" of 2D NM often limits the loading of antimicrobial components needed for synergistic bactericidal actions. Here, inspired by the highly ornamented siliceous frustules of diatoms, we prepared 2D ultrathin (<20 nm) and rigid "nanofrustule" plates via the out-of-plane growth of cetyltrimethylammonium bromide (CTAB) directed silica mesostructures on the surfaces of 2D graphene oxide nanosheets. The nanofrustules were characterized by the presence of mesoporous channels with a pore size of 3 nm and a high specific surface area of 674 m2 g-1. S-nitrosothiol-modification on the silica surfaces enables the development of a novel anti-infective nitric oxide (NO) releasing NO-nanofrustule system. The cage-like mesoporous silica architecture enabled a controlled and sustainable release of NO from the NO-nanofrustules under physiological conditions. The NO-nanofrustules displayed broad antibacterial effects against Staphylococcus aureus and Escherichia coli with a minimum inhibitory concentration of 250 μg ml-1. Mechanistic studies revealed that the antibacterial property of NO-nanofrustules was attained via a unique "capture-and-release" mode-of-action. The first step entailed the capture of the bacteria by the NO-nanofrustules to form micro-aggregates. This was followed by the release of high levels of NO to the captured bacteria to elicit a potent anti-infective effect. In combination with the lack of cytotoxicity in human dermal cells, the 2D hybrid NO-nanofrustules may be utilized to combat wound infections in clinical settings.

Antibacterial Porous Coaxial Drug-Carrying Nanofibers for Sustained Drug-Releasing Applications

The phenomenon of drug burst release is the main problem in the field of drug delivery systems, as it means that a good therapeutic effect cannot be acheived. Nanofibers developed by electrospinning technology have large specific surface areas, high porosity, and easily controlled morphology. They are being considered as potential carriers for sustained drug release. In this paper, we obtained polycaprolactone (PCL)/polylactic acid (PLA) core-shell porous drug-carrying nanofibers by using coaxial electrospinning technology and the nonsolvent-induced phase separation method. Roxithromycin (ROX), a kind of antibacterial agent, was encapsulated in the core layer. The morphology, composition, and thermal properties of the resultant nanofibers were characterized by scanning electron microscopy (SEM), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). Besides this, the in vitro drug release profile was investigated; it showed that the release rate of the prepared coaxial porous nanofibers with two different pore sizes was 30.10 ± 3.51% and 35.04 ± 1.98% in the first 30 min, and became 92.66 ± 3.13% and 88.94 ± 1.58% after 14 days. Compared with the coaxial nonporous nanofibers and nanofibers prepared by uniaxial electrospinning with or without pores, the prepared coaxial porous nanofibers revealed that the burst release was mitigated and the dissolution rate of the hydrophobic drugs was increased. The further antimicrobial activity demonstrated that the inhibition zone diameter of the coaxial nanofibers with two different pore sizes was 1.70 ± 0.10 cm and 1.73 ± 0.23 cm, exhibiting a good antibacterial effect against Staphylococcus aureus. Therefore, the prepared nanofibers with the coaxial porous structures could serve as promising drug delivery systems.

Electrospun polycaprolactone/hydroxyapatite/ZnO films as potential biomaterials for application in bone-tendon interface repair

The bone-tendon interface (BTI) is a graded structure consisting of bone, mineralized and nonmineralized fibrocartilage, and tendons. Due to the complexity of the BTI structure, BTI healing is particularly challenging. To achieve a better material for BTI healing, polycaprolactone (PCL)/hydroxyapatite (HA)/ZnO films were constructed by the electrospinning method; in addition, the relevant material characteristics were tested. After culturing MC3T-E1 cells, ATDC5 cells, mouse primary fibrochondrocytes, and mouse primary tenocytes on films, PCL-5%HA-1%ZnO films (HA and ZnO weight ratios of 5% and 1%, respectively) displayed superior cell compatibility and cell adhesion. PCL-5%HA-1%ZnO films also promoted osteogenesis, chondrogenesis, fibrocartilage formation, and tendon healing. The antibacterial characteristics of PCL-5%HA-1%ZnO films were also identified in this study. The PCL-5%HA-1%ZnO films have great application potential in the field of BTI repair.

An oxidative stress-responsive electrospun polyester membrane capable of releasing anti-bacterial and anti-inflammatory agents for postoperative anti-adhesion

Peritendinous adhesion, secondary to the repair surgery of tendon rupture or injury, is one of the most common causes of reoperation, owing to the proliferation of fibrous tissue and excessive collagen synthesis caused by the residing inflammatory cells. In this study, a smart oxidative stress-responsive electrospun polyester membrane (EPM) was fabricated as both physical barrier and reservoir of curcumin/celecoxib (CUR/CEL) to prevent peritendinous adhesion. The multicomponent EPM was designed to release the encapsulated drugs in response to oxidative stress of the local microenvironment induced by inflammation. Specifically, sulfides in the EPM were able to react with reactive oxygen species (ROS) and become hydrophilic sulfoxide or sulfone to accelerate the release rate of drugs and regulate oxidative stress level in the inflammatory site intelligently. The oxidation-sensitive multicomponent EPM loaded with CUR and CEL was tested for anti-adhesion capacity in vitro and in vivo. An excellent ROS-sensitive degradation behavior and good cytocompatibility with cell viability of above 85% were presented with the fabricated EPM. The CUR- or CEL-loaded EPM possessed a better anti-adhesion ability compared with EPM without the drugs. Nevertheless, they were inferior to the EPM simultaneously loaded with both drugs, where the adhesion rate and fibrous adhesion number in the EPM+CUR/CEL group were close to extremely low values of about zero, demonstrating that CUR and CEL could synergistically prevent peritendinous adhesion. More interestingly, the multicomponent EPM was able to react with the local oxidative stress, leading to a smart and sustained behavior of releasing approximately 80% of the drug within 20 days. Overall, the smart multicomponent EPM offers a promising barrier strategy to prevent peritendinous adhesion.

Nanoclay-based drug delivery systems and their therapeutic potentials

Safe, therapeutically effective, and patient-compliant drug delivery systems are needed to design novel tools and strategies to combat the deadliest of diseases such as cancer, SARS, H7N9 avian influenza, and dengue infection. The major challenges in drug delivery are cytotoxicity, poor biodistribution, insufficient functionality, ineffective drug incorporation in delivery devices, and subsequent drug release. Clay minerals are a class of nanolayered silicates that have good biocompatibility, high specific surface area, chemical inertness, colloid, and thixotropy, and are attractive practical and potential nanomaterials in medicine. These properties enable the usage of nanoclays as drug carriers for the delivery of antibiotics, antihypertensive drugs, anti-psychotic, and anticancer drugs. The review examines the latest advances in nanoclay-based drug delivery systems and related applications in gene therapy and tissue engineering. Clay minerals, particularly montmorillonite, kaolinite, and halloysite are used to delay and/or target drug release or even improve drug dissolution due to their surface charge. Chemical modification of clay minerals such as intercalation of ions into the interlayer space of clay minerals or surface modification of clay minerals is a strategy to tune the properties of nanoclays for the loading and release of a drug. The modified nanoclay can take up drugs by encapsulation, immobilization, ion exchange reaction, or electrostatic interactions. Controlled drug release from the drug-clay originates from the incorporation and interactions between the drug and inorganic layers, including electrostatic interactions and hydrogen bonding. Montmorillonite has proven non-toxic through hematological, biochemical, and histopathological analyses in rat. Montmorillonite can also act as a potent detoxifier. Halloysite nanotubes can bind synthetic and biological components such as chitosan, gelatin, and alginate innate nanocarriers for the improved loading and controlled release of drugs, proteins, and DNA. The peculiar properties of clay nanoparticles lead to promising applications in drug delivery, gene delivery, tissue engineering, cancer and stem cell isolation, and bioimaging.

Knittable and Sewable Spandex Yarn with Nacre-Mimetic Composite Coating for Wearable Health Monitoring and Thermo- and Antibacterial Therapies

The emerging personal healthcare has significantly propelled the development of advanced wearable electronics with novel functions of providing diagnostic information and point-of-care therapies for specific diseases. However, it is still challenging to simultaneously achieve high sensitivity for health biomonitoring and multifunction integration for point-of-care therapies in a one single flexible, lightweight yet robust fiber-based device. Here, a knittable and sewable spandex yarn with conductive nacre-mimetic composite coating has been developed through an alternant dip-coating method employing MXene nanosheets as the "brick" and polydopamine (PDA)/Ni²⁺ as the "mortar". The resultant spandex yarn coating with MXene/PDA/Ni²⁺ (MPNi@Spandex) can be assembled as a strain sensor with high sensitivity (up to 5.7 × 10⁴ for the gauge factor), wide sensing range (∼61.2%), and low detection limit (0.11%) to monitor the biological activities of the human body. Furthermore, MPNi@Spandex displays great potential to give on-demand thermotherapy by virtue of the fast response to near-infrared irradiation, controllable surface temperature, and applicability even under sewing conditions. In addition, MPNi@Spandex knitted textiles demonstrate a strong antibacterial effect due to the sharp edges, anionic, and hydrophilic nature of MXene nanosheets. Remarkably, near-infrared irradiation further improves the bacteria-killing efficiency of an MPNi@Spandex knitted textile to more than 99.9%. This work paves the way for the design of multifunctional wearable electronics with an all-in-one theranostic platform for personal healthcare.

Injectable chitosan-quince seed gum hydrogels encapsulated with curcumin loaded-halloysite nanotubes designed for tissue engineering application

The goal of tissue engineering is to assemble functional constructs that restore, maintain, or improve damaged tissues or organs. Hydrogels formed with natural polymers display high potential in artificial scaffolds for tissue repair as they can resemble the extracellular matrices. Thus, the aim of this study was to design nanocomposite hydrogels of chitosan/oxidized-modified quince seed gum/curcumin-loaded in halloysite nanotubes (CS/OX-QSG/CUR-HNTs) for tissue engineering applications. The produced hydrogels were analyzed for thermal stability, degradation, swelling ratio, gelling time and mechanical properties. The results showed that with increasing content of OX-QSG, thermal stability, swelling ratio, and degradation rate of hydrogels were improved. Notably, the optimal CS/OX-QSG hydrogel with ratio of 25:75 exhibited rapid gelation behavior (<50 s) and improved compressive strength (3.96 ± 0.64 MPa), representing the suitable hydrogel for application in tissue engineering. The MTT test showed that these hydrogels were non-toxic and any reduction or stop of NIH-3 T3 cells growth wasn't observed over time. In addition, CS/OX-QSG 25:75 hydrogels containing CUR-HNTs with 10 and 30% content was significantly (P < 0.05) enhanced cell growth and proliferation (around 150%). Obtained results illustrated that CS/OX-QSG hydrogels with ratio of 25:75 and the content of 30% CUR-HNTs can be an effective scaffold for application in tissue engineering.