Carbon nanotube-incorporated multilayered cellulose acetate nanofibers for tissue engineering applications

Cellulose-based composite scaffolds for bone tissue engineering and localized drug delivery

Natural bone constitutes a complex and organized structure of organic and inorganic components with limited ability to regenerate and restore injured tissues, especially in large bone defects. To improve the reconstruction of the damaged bones, tissue engineering has been introduced as a promising alternative approach to the conventional therapeutic methods including surgical interventions using allograft and autograft implants. Bioengineered composite scaffolds consisting of multifunctional biomaterials in combination with the cells and bioactive therapeutic agents have great promise for bone repair and regeneration. Cellulose and its derivatives are renewable and biodegradable natural polymers that have shown promising potential in bone tissue engineering applications. Cellulose-based scaffolds possess numerous advantages attributed to their excellent properties of non-toxicity, biocompatibility, biodegradability, availability through renewable resources, and the low cost of preparation and processing. Furthermore, cellulose and its derivatives have been extensively used for delivering growth factors and antibiotics directly to the site of the impaired bone tissue to promote tissue repair. This review focuses on the various classifications of cellulose-based composite scaffolds utilized in localized bone drug delivery systems and bone regeneration, including cellulose-organic composites, cellulose-inorganic composites, cellulose-organic/inorganic composites. We will also highlight the physicochemical, mechanical, and biological properties of the different cellulose-based scaffolds for bone tissue engineering applications.

Nanoarchitectonics beyond perfect order - not quite perfect but quite useful

Nanoarchitectonics, like architectonics, allows the design and building of structures, but at the nanoscale. Unlike those in architectonics, and even macro-, micro-, and atomic-scale architectonics, the assembled structures at the nanoscale do not always follow the projected design. In fact, they do follow the projected design but only for self-assembly processes producing structures with perfect order. Here, we look at nanoarchitectonics allowing the building of nanostructures without a perfect arrangement of building blocks. Here, fabrication of structures from molecules, polymers, nanoparticles, and nanosheets to polymer brushes, layer-by-layer assembly structures, and hydrogels through self-assembly processes is discussed, where perfect order is not necessarily the aim to be achieved. Both planar substrate and spherical template-based assemblies are discussed, showing the challenging nature of research in this field and the usefulness of such structures for numerous applications, which are also discussed here.

Construction of ultrasound-responsive urokinase precise controlled-release nanoliposome applied for thrombolysis

Urokinase is widely used in the dissolution of an acute pulmonary embolism due to its high biocatalytic effect. However, how to precisely regulate its dose, avoid the side effects of hemolysis or ineffective thrombolysis caused by too high or too low a dose, and seize the golden time of acute pulmonary embolism are the key factors for its clinical promotion. Therefore, based on the precise design of a molecular structure, an ultrasonic-responsive nanoliposome capsule was prepared in this paper. Singlet oxygen is continuously generated under the interaction of the ultrasonic cavitation effect and the sonosensitizer protoporphyrin, and the generated singlet oxygen will break the thiol acetone bond between the hydrophilic head and the hydrophobic tail of the liposome, and the lipid The body structure disintegrates rapidly, and the urokinase encapsulated inside is rapidly released, down-regulating the expression of fibrinogen in the body, and exerting a thrombolytic function. The in vitro and in vivo results show that the smart urokinase nanoliposomes prepared by us have sensitive and responsive cytocompatibility to ultrasound and good in vivo thrombolytic properties for acute pulmonary embolism, which provides a new strategy for clinical acute pulmonary embolism thrombolysis.

Co-Loading of Inorganic Nanoparticles and Natural Oil in the Electrospun Janus Nanofibers for a Synergetic Antibacterial Effect

Side-by-side electrospinning is a powerful but challenging technology that can be used to prepare Janus nanofibers for various applications. In this work, cellulose acetate (CA) and polycaprolactone (PCL) were used as polymer carriers for silver nanoparticles (Ag NPs) and lavender oil (LO), respectively, processing these into two-compartment Janus fibers. A bespoke spinneret was used to facilitate the process and prevent the separation of the working fluids. The process of side-by-side electrospinning was recorded with a digital camera, and the morphology and internal structure of the products were characterized by electron microscopy. Clear two-compartment fibers are seen. X-ray diffraction patterns demonstrate silver nanoparticles have been successfully loaded on the CA side, and infrared spectroscopy indicates LO is dispersed on the PCL side. Wetting ability and antibacterial properties of the fibers suggested that PCL-LO//CA-Ag NPs formulation had strong antibacterial activity, performing better than fibers containing only one active component. The PCL-LO//CA-Ag NPs had a 20.08 ± 0.63 mm inhibition zone for E. coli and 19.75 ± 0.96 mm for S. aureus. All the fibers had water contact angels all around 120°, and hence, have suitable hydrophobicity to prevent water ingress into a wound site. Overall, the materials prepared in this work have considerable promise for wound healing applications.

A stable and easily regenerable solid amine adsorbent derived from a polyethylenimine-impregnated dialdehyde-cellulose/graphene-oxide composite

A DAC-GO composite adsorbent with high CO2 adsorption capacity and low regeneration energy consumption was prepared through oxidation-gelation and crosslinking-amination.

An Overview of the Design of Chitosan-Based Fiber Composite Materials

Chitosan composite fibrous materials continue to generate significant interest for wastewater treatment, food packaging, and biomedical applications. This relates to the relatively high surface area and porosity of such fibrous chitosan materials that synergize with their unique physicochemical properties. Various methods are involved in the preparation of chitosan composite fibrous materials, which include the modification of the biopolymer that serve to alter the solubility of chitosan, along with post-treatment of the composite materials to improve the water stability or to achieve tailored functional properties. Two promising methods to produce such composite fibrous materials involve freeze-drying and electrospinning. Future developments of such composite fibrous materials demands an understanding of the various modes of preparation and methods of structural characterization of such materials. This review contributes to an understanding of the structure–property relationships of composite fibrous materials that contain chitosan, along with an overview of recent advancements concerning their preparation.

Constructing 3D Macroporous Microfibrous Scaffolds with a Featured Surface by Heat Welding and Embossing

Three-dimensional (3D) microfibrous scaffolds hold great promise for biomedical applications due to their good mechanical properties and biomimetic structure similar to that of the fibrous natural extracellular matrix. However, the large diameter and smooth surface of microfibers provide limited cues for regulating cell activity and behaviors. In this work, we report a facile heat-welding-and-embossing strategy to develop 3D macroporous microfibrous scaffolds with a featured surface topography. Here, solid monosodium glutamate (MSG) particles with crystalline ridge-like surface features play a key role as templates in both the formation of scaffold pores and the surface embossing of scaffold fibers when short thermoplastic polypropylene microfibers were heat-welded. The embossing process can be programmed by adjusting heating temperatures and MSG/fiber ratios. Compared to traditional 3D microfibrous scaffolds, the as-welded 3D scaffolds show higher compressive strength and modulus. Taking mouse C2C12 myoblasts as a model cell line, the scaffolds with embossed surface features significantly promoted the growth of cells, interactions of cells and scaffolds, and formation of myotubes. The findings indicate that the as-prepared 3D scaffolds are a good platform for cell culture study. The facile strategy can be applied to fabricate different fibrous scaffolds by changing the combination of templates and thermoplastic polymer fibers with a melting temperature lower than that of the template. The obtained insights in this work could provide a guide and inspiration for the design and fabrication of functional 3D fibrous scaffolds.

Applications of Nanocellulose/Nanocarbon Composites: Focus on Biotechnology and Medicine

Nanocellulose/nanocarbon composites are newly emerging smart hybrid materials containing cellulose nanoparticles, such as nanofibrils and nanocrystals, and carbon nanoparticles, such as "classical" carbon allotropes (fullerenes, graphene, nanotubes and nanodiamonds), or other carbon nanostructures (carbon nanofibers, carbon quantum dots, activated carbon and carbon black). The nanocellulose component acts as a dispersing agent and homogeneously distributes the carbon nanoparticles in an aqueous environment. Nanocellulose/nanocarbon composites can be prepared with many advantageous properties, such as high mechanical strength, flexibility, stretchability, tunable thermal and electrical conductivity, tunable optical transparency, photodynamic and photothermal activity, nanoporous character and high adsorption capacity. They are therefore promising for a wide range of industrial applications, such as energy generation, storage and conversion, water purification, food packaging, construction of fire retardants and shape memory devices. They also hold great promise for biomedical applications, such as radical scavenging, photodynamic and photothermal therapy of tumors and microbial infections, drug delivery, biosensorics, isolation of various biomolecules, electrical stimulation of damaged tissues (e.g., cardiac, neural), neural and bone tissue engineering, engineering of blood vessels and advanced wound dressing, e.g., with antimicrobial and antitumor activity. However, the potential cytotoxicity and immunogenicity of the composites and their components must also be taken into account.

Characterizations and application of CA/ZnO/AgNP composite nanofibers for sustained antibacterial properties

Although silver based nanofibers possess excellent bactericidal and bacteriostatic characteristics. However, excess release/contact with silver may induce harmful side-effects including carcinoma, argyria, argyrosis and allergies. Similarly, silver depletion may limit prolonged antibacterial activities as well. Thus present research proposes electrospun CA/ZnO/AgNPs composite nanofibers for biologically safer and sustained antibacterial applications. The ZnO/AgNPs were synthesized using dopamine hydrochloride (Dopa) as reducing agent to immobilize AgNPs on ZnO nanoparticles. A simple solution-mixing procedure effectively generated AgNPs on ZnO nanoparticles. Strong adhesive characteristics of Dopa initiate adsorption of silver ions on ZnO nanoparticle surfaces and its metal ion reducing properties generate AgNPs. Additionally, the Dopa mediation generates strongly adhered AgNPs. The ZnO/AgNPs were used to fabricate CA/ZnO/AgNPs nanofibers. Characterization techniques, XRD, XPS, TEM, FTIR and SEM confirmed synthesis of nanocomposites. Crystallite sizes of ZnO and AgNPs calculated by Debye-Scherrer equation were 17.85 nm and 11.68 nm respectively. Antibacterial assays confirmed CA/ZnO/AgNP's effectiveness in growth inhibition of E. coli and S. aureus strains on agar plate and in liquid medium. The nanofiber composites demonstrated 100% bactericidal properties against both the test strains. Bacterial growth inhibition in LB medium for 108 h indicated suitability of CA/ZnO/AgNPs composite nanofibers in sustained antibacterial applications such as antibacterial wound dressings and other applications demanding sustained antimicrobial properties.

Synergistic Effect and Characterization of Graphene/Carbon Nanotubes/Polyvinyl Alcohol/Sodium Alginate Nanofibrous Membranes Formed Using Continuous Needleless Dynamic Linear Electrospinning

In this study, a self-made continuous needleless dynamic linear electrospinning technique is employed to fabricate large-scale graphene (Gr)/carbon nanotubes (CNT)/polyvinyl alcohol (PVA)/sodium alginate (SA) nanofibrous membranes. The synergistic effect of Gr and CNT fillers in the PVA/SA membrane is explored in depth by changing the volume ratio (v/v) of Gr and CNT as 10:0, 8:2, 6:4, 4:6, 2:8, and 0:10. Microstructure, functional group, conductivity, and hydrophilicity of PVA/SA/Gr/CNT membranes was characterized. Results show that the linear electrode needleless electrospinning technique can be spun into 200-nm diameter fibers. The PVA/SA/Gr/CNT fibrous membrane has good hydrophilicity and thermal stability. A Gr/CN ratio of 6:4 possessed the optimal synergistic effect, which showed the lowest surface resistivity of 2.53 × 103 Ω/m2. This study will provide a reference for the large-scale preparation of nanofibrous membrane used as a artificial nerve conduit in the future.

The Photothermal Effect of Targeted Methotrexate-Functionalized Multi-Walled Carbon Nanotubes on MCF7 Cells

Our goal is to reduce the release rate of methotrexate (MTX) and increase cell death efficiency.Carboxylated multi-walled carbon nanotubes (MWCNT-COOH) were functionalized with MTX as a cytotoxic agent, FA as a targeting moiety and polyethylene amine (PEI) as a hydrophilic agent. Ultimately, MWCNT-MTX and MWCNT-MTX-PEI-FA were synthesized. Methotrexate release studies were conducted in PBS and cytotoxic studies were carried out by means of the MTT tassay. Methotrexate release studies from these two carriers demonstrated that the attachment of PEI-FA onto MWCNT-MTX reduces the release rate of methotrexate. The IC50 of MWCNT-MTX-PEI-FA and MWCNT-MTX have been calculated as follows: 9.89 ± 0.38 and 16.98 ± 1.07 µg/mL, respectively. Cytotoxic studies on MWCNT-MTX-PEI-FA and MWCNT-MTX in the presence of an IR laser showed that at high concentrations, they had similar toxicities due to the MWCNT's photothermal effect. Targeting effect studies in the presence of the IR laser on the cancer cells have shown that MWCNT-MTX-PEI-FA, MWCNT-MTX, and f-MWCNT have triggered the death of cancer cells by 55.11 ± 1.97%, 49.64 ± 2.44%, and 37 ± 0.70%, respectively. The release profile of MTX in MWCNT-MTX-PEI-FA showed that the presence of PEI acts as a barrier against release and reduces the MTX release rate. In the absence of a laser, MWCNT-MTX-PEI-FA exhibits the highest degree of cytotoxicity. In the presence of a laser, the cytotoxicity of MWCNT-MTX and MWCNT-MTX-PEI-FA has no significant difference. Targeting studies have shown that MWCNT-MTX-PEI-FA can be absorbed by cancer cells exclusively.

Fabrication of random and aligned-oriented cellulose acetate nanofibers containing betamethasone sodium phosphate: structural and cell biocompatibility evaluations

The objective of this work was to prepare electrospun cellulose acetate (CA) nanofibers containing betamethasone sodium phosphate (BSP). Two different morphologies including random and aligned orientations were rationally designed to improve the performance of samples in in vitro experiments. By comparing the CA nanofibrous samples with randomly and aligned-oriented morphologies, the scanning electron microscopy images showed that the neat aligned-oriented nanofibers with an average diameter of 180±15 nm could be obtained using a high-speed rotating collector. Subsequently, the tensile test confirmed that the aligned CA nanofibers had higher mechanical properties than that of the randomly oriented ones. Moreover, the BSP release profile obtained by UV-vis spectrophotometry depicted that the aligned samples had an initial burst release of BSP followed by a slow penetration of the drug with a gentle slope during 72 h. Furthermore, the ultimate amounts of BSP released from the random and aligned CA nanofibers into the phosphate buffer solution were 63% and 53%, respectively. Finally, human adipose-derived mesenchymal stem cells were seeded on both aligned and random electrospun CA nanofibrous samples containing BSP. The thiazolyl blue and hematoxylin and eosin staining results showed that the BSP-loaded nanofibers with the aligned morphology provided the most suitable environment for the cells’ growth, viability, and proliferation.

Immunosensor for Pancreatic Cancer Based on Electrospun Nanofibers Coated with Carbon Nanotubes or Gold Nanoparticles

We report the fabrication of immunosensors based on nanostructured mats of electrospun nanofibers of polyamide 6 and poly(allylamine hydrochloride) coated either with multiwalled carbon nanotubes (MWCNTs) or gold nanoparticles (AuNPs), whose three-dimensional structure was suitable for the immobilization of anti-CA19-9 antibodies to detect the pancreatic cancer biomarker CA19-9. Using impedance spectroscopy, the sensing platform was able to detect CA19-9 with a detection limit of 1.84 and 1.57 U mL-1 for the nanostructured architectures containing MWCNTs and AuNPs, respectively. The high sensitivity achieved can be attributed to the irreversible adsorption between antibodies and antigens, as confirmed with polarization-modulated infrared reflection absorption spectroscopy. The adsorption mechanism was typical Langmuir-Freundlich processes. The high sensitivity and selectivity of the immunosensors were also explored in tests with blood serum from patients with distinct concentrations of CA19-9, for which the impedance spectra data were processed with a multidimensional projection technique. The robustness of the immunosensors in dealing with patient samples without suffering interference from analytes present in biological fluids is promising for a simple, effective diagnosis of pancreatic cancer at early stages.

Nanotechnology for Neuroscience: Promising Approaches for Diagnostics, Therapeutics and Brain Activity Mapping

Unlocking the secrets of the brain is a task fraught with complexity and challenge - not least due to the intricacy of the circuits involved. With advancements in the scale and precision of scientific technologies, we are increasingly equipped to explore how these components interact to produce a vast range of outputs that constitute function and disease. Here, an insight is offered into key areas in which the marriage of neuroscience and nanotechnology has revolutionized the industry. The evolution of ever more sophisticated nanomaterials culminates in network-operant functionalized agents. In turn, these materials contribute to novel diagnostic and therapeutic strategies, including drug delivery, neuroprotection, neural regeneration, neuroimaging and neurosurgery. Further, the entrance of nanotechnology into future research arenas including optogenetics, molecular/ion sensing and monitoring, and piezoelectric effects is discussed. Finally, considerations in nanoneurotoxicity, the main barrier to clinical translation, are reviewed, and direction for future perspectives is provided.

Carbon Nanofiber Reinforced Nonmulberry Silk Protein Fibroin Nanobiocomposite for Tissue Engineering Applications

Natural silk protein fibroin based biomaterial are exploited extensively in tissue engineering due to their aqueous preparation, slow biodegradability, mechanical stability, low immunogenicity, dielectric properties, tunable properties, sufficient and easy availability. Carbon nanofibers are reported for their conductivity, mechanical strength and as delivery vehicle of small molecules. Limited evidence about their cytocompatibility and their poor dispersibility are the key issues for them to be used as successful biomaterials. In this study, carbon nanofiber is functionalized and dispersed using the green aqueous-based method within the regenerated nonmulberry (tropical tasar: Antheraea mylitta) silk fibroin (AmF), which contains inherent - R-G-D- sequences. Carbon nanofiber (CNF) reinforced silk films are fabricated using solvent evaporation technique. Different biophysical characterizations and cytocompatibility of the composite matrices are assessed. The investigations show that the presence of the nanofiber greatly influence the property of the composite films in terms of excellent conductivity (up to 6.4 × 10^-6 Mho cm, which is 3 orders of magnitude of pure AmF matrix), and superior tensile modulus (up to 1423 MPa, which is 12.5 times more elastic than AmF matrix). The composite matrices (composed of up to 1 mg of CNF per mL of 2% AmF) also support better fibroblast cell growth and proliferation. The fibroin-carbon nanofiber matrices can lead to a novel multifunctional biomaterial platform, which will support conductive as well as load bearing tissue (such as, muscle, bone, and nerve tissue) regenerations.

Nanocarbons in Electrospun Polymeric Nanomats for Tissue Engineering: A Review

Electrospinning is a versatile process technology, exploited for the production of fibers with varying diameters, ranging from nano- to micro-scale, particularly useful for a wide range of applications. Among these, tissue engineering is particularly relevant to this technology since electrospun fibers offer topological structure features similar to the native extracellular matrix, thus providing an excellent environment for the growth of cells and tissues. Recently, nanocarbons have been emerging as promising fillers for biopolymeric nanofibrous scaffolds. In fact, they offer interesting physicochemical properties due to their small size, large surface area, high electrical conductivity and ability to interface/interact with the cells/tissues. Nevertheless, their biocompatibility is currently under debate and strictly correlated to their surface characteristics, in terms of chemical composition, hydrophilicity and roughness. Among the several nanofibrous scaffolds prepared by electrospinning, biopolymer/nanocarbons systems exhibit huge potential applications, since they combine the features of the matrix with those determined by the nanocarbons, such as conductivity and improved bioactivity. Furthermore, combining nanocarbons and electrospinning allows designing structures with engineered patterns at both nano- and microscale level. This article presents a comprehensive review of various types of electrospun polymer-nanocarbon currently used for tissue engineering applications. Furthermore, the differences among graphene, carbon nanotubes, nanodiamonds and fullerenes and their effect on the ultimate properties of the polymer-based nanofibrous scaffolds is elucidated and critically reviewed.

The influence of melt mixing on the stability of cellulose acetate and its carbon nanotube composites

Cellulose derivatives, such as cellulose acetate (CA), are commonly used due to their ease of processing. These polymers present interesting mechanical properties and biodegradability, but low thermal stability under melt processing conditions. Composites of carbon nanotubes (CNTs) and cellulose derivatives are expected to present enhanced properties, depending on the effect of nanotubes on polymer structure and thermal properties. This work aims to investigate the influence of melt mixing on the stability of CA and its CNT composites. Composites with 0 wt%, 0.1 wt% and 0.5 wt% CNTs, as received and functionalized with pyrrolidine groups, were prepared using a batch mixer and an extruder. Chain scission of CA occurred during processing, but the effect was considerably reduced in the presence of CNTs. The incorporation of small amounts of CNTs (with or without functionalization) decreased polymer degradation by thermomechanical effects induced during polymer processing.

Ibuprofen loaded PLA nanofibrous scaffolds increase proliferation of human skin cells in vitro and promote healing of full thickness incision wounds in vivo

This article presents successful incorporation of ibuprofen in polylactic acid (PLA) nanofibers to create scaffolds for the treatment of both acute and chronic wounds. Nanofibrous PLA scaffolds containing 10, 20, or 30 wt % ibuprofen were created and ibuprofen release profiles quantified. In vitro cytotoxicity to human epidermal keratinocytes (HEK) and human dermal fibroblasts (HDF) of the three scaffolds with varying ibuprofen concentrations were evaluated and compared to pure PLA nanofibrous scaffolds. Thereafter, scaffolds loaded with ibuprofen at the concentration that promoted human skin cell viability and proliferation (20 wt %) were evaluated in vivo in nude mice using a full thickness skin incision model to determine the ability of these scaffolds to promote skin regeneration and/or assist with scarless healing. Both acellular and HEK and HDF cell-seeded 20 wt % ibuprofen loaded nanofibrous bandages reduced wound contraction compared with wounds treated with Tegaderm™ and sterile gauze. Newly regenerated skin on wounds treated with cell-seeded 20 wt % ibuprofen bandages exhibited significantly greater blood vessel formation relative to acellular ibuprofen bandages. We have found that degradable anti-inflammatory scaffolds containing 20 wt % ibuprofen promote human skin cell viability and proliferation in vitro, reduce wound contraction in vivo, and when seeded with skin cells, also enhance new blood vessel formation. The approaches and results reported here hold promise for multiple skin tissue engineering and wound healing applications. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 327-339, 2017.

Enhanced proliferation and osteogenic differentiation of mesenchymal stem cells on graphene oxide-incorporated electrospun poly(lactic-co-glycolic acid) nanofibrous mats

Currently, combining biomaterial scaffolds with living stem cells for tissue regeneration is a main approach for tissue engineering. Mesenchymal stem cells (MSCs) are promising candidates for musculoskeletal tissue repair through differentiating into specific tissues, such as bone, muscle, and cartilage. Thus, successfully directing the fate of MSCs through factors and inducers would improve regeneration efficiency. Here, we report the fabrication of graphene oxide (GO)-doped poly(lactic-co-glycolic acid) (PLGA) nanofiber scaffolds via electrospinning technique for the enhancement of osteogenic differentiation of MSCs. GO-PLGA nanofibrous mats with three-dimensional porous structure and smooth surface can be readily produced via an electrospinning technique. GO plays two roles in the nanofibrous mats: first, it enhances the hydrophilic performance, and protein- and inducer-adsorption ability of the nanofibers. Second, the incorporated GO accelerates the human MSCs (hMSCs) adhesion and proliferation versus pure PLGA nanofiber and induces the osteogenic differentiation. The incorporating GO scaffold materials may find applications in tissue engineering and other fields.

Rational design of nanofiber scaffolds for orthopedic tissue repair and regeneration

This article reviews recent significant advances in the design of nanofiber scaffolds for orthopedic tissue repair and regeneration. It begins with a brief introduction on the limitations of current approaches for orthopedic tissue repair and regeneration. It then illustrates that rationally designed scaffolds made up of electrospun nanofibers could be a promising solution to overcome the problems that current approaches encounter. The article also discusses the intriguing properties of electrospun nanofibers, including control of composition, structures, orders, alignments and mechanical properties, use as carriers for topical drug and/or gene sustained delivery, and serving as substrates for the regulation of cell behaviors, which could benefit musculoskeletal tissue repair and regeneration. It further highlights a few of the many recent applications of electrospun nanofiber scaffolds in repairing and regenerating various orthopedic tissues. Finally, the article concludes with perspectives on the challenges and future directions for better design, fabrication and utilization of nanofiber scaffolds for orthopedic tissue engineering.

Poly(amidoamine) dendrimer-enabled simultaneous stabilization and functionalization of electrospun poly(γ-glutamic acid) nanofibers

We report a facile and general approach to using generation 2 (G2) poly(amidoamine) (PAMAM) dendrimers for simultaneous stabilization and functionalization of electrospun poly(γ-glutamic acid) nanofibers (γ-PGA NFs). In this study, uniform γ-PGA NFs with a smooth morphology were generated using electrospinning technology. In order to endow the NFs with good water stability, amine-terminated G2.NH2 PAMAM dendrimers were utilized to crosslink the γ-PGA NFs via 1-ethyl-3-(3-dimethylami-nopropyl) carbodiimide coupling chemistry. Under the optimized crosslinking conditions, G2.NH2 dendrimers partially modified with fluorescein isothiocyanate (FI) or folic acid (FA) were used to crosslink γ-PGA NFs. Our results reveal that G2.NH2-FI is able to simultaneously render the NFs with good water stability and fluorescence property, while G2.NH2-FA is able to simultaneously endow the NFs with water stability and the ability to capture FA receptor-overexpressing cancer cells in vitro via ligand-receptor interaction. With the tunable dendrimer surface chemistry, multifunctional water-stable γ-PGA-based NFs may be generated via a dendrimer crosslinking approach, thereby providing diverse applications in the areas of biosensing, tissue engineering, drug delivery, and environmental sciences.

Selective removal of mercury ions using thymine-grafted electrospun polymer nanofibers

Thymine-grafted poly(vinyl alcohol)–polyethyleneimine nanofibers can be formed for high-efficiency and high-specificity removal of mercury ions from aqueous solution.

Dendrimer-functionalized electrospun cellulose acetate nanofibers for targeted cancer cell capture applications

Multifunctional folic acid-functionalized dendrimers can be modified on the surface of electrospun cellulose acetate nanofibers for the specific capture of FAR-overexpressing cancer cells.

Novel 3D electrospun scaffolds with fibers oriented randomly and evenly in three dimensions to closely mimic the unique architectures of extracellular matrices in soft tissues: fabrication and mechanism study

In this work, novel electrospun scaffolds with fibers oriented randomly and evenly in three dimensions (3D) including in the thickness direction were developed based on the principle of electrostatic repulsion. This unique structure is different from most electrospun scaffolds with fibers oriented mainly in one direction. The structure of novel 3D scaffolds could more closely mimic the 3D randomly oriented fibrous architectures in many native extracellular matrices (ECMs). The cell culture results of this study indicated that, instead of becoming flattened cells when cultured in conventional electrospun scaffolds, the cells cultured on novel 3D scaffolds could develop into stereoscopic topographies, which highly simulated in vivo 3D cellular morphologies and are believed to be of vital importance for cells to function and differentiate appropriately. Also, due to the randomly oriented fibrous structure, improvement of nearly 5 times in cell proliferation could be observed when comparing our 3D scaffolds with 2D counterparts after 7 days of cell culture, while most currently reported 3D scaffolds only showed 1.5- to 2.5-fold improvement for the similar comparison. One mechanism of this fabrication process has also been proposed and showed that the rapid delivery of electrons on the fibers was the crucial factor for formation of 3D architectures.