Spongy Gels by a Top-Down Approach from Polymer Fibrous Sponges

Multifunctional chitosan-based gel sponge with efficient antibacterial, hemostasis and strong adhesion

Developing wound dressings with solid adhesive properties that enable efficient, painless hemostasis and prevent wound infection remain a huge challenge. Herein, the tris(hydroxymethyl) methyl glycine-modified chitosan derivative (CTMG) was prepared and freeze-dried after simply adjusting the concentration of CTMG to obtain the chitosan-based gel sponge with desired multi-hollow structure, special antibacterial and biocompatibility. The adhesion strength on porcine skin was impressive up to 113 KPa, much higher than fibrin glue. It can withstand the pressure that far exceeds blood pressure. CTMG exhibits bacteriostatic abilities as demonstrated in a bacteriostatic assay, and alongside biocompatibility, as shown in cytotoxicity and hemolytic assays. Moreover, CTMG gel sponge showed hemostatic properties in both in vivo and in vitro hemostasis experiments. During an experiment on liver hemorrhage in rats, CTMG gel sponge proved to be more effective in controlling bleeding than other hemostatic sponges available on the market, indicating its promising hemostatic properties. CTMG gel sponge possesses the potential to function as a wound dressing and hemostatic material, making it suitable for various clinical applications.

Direct Ink Writing of Pickering Emulsions Generates Ultralight Conducting Polymer Foams with Hierarchical Structure and Multifunctionality

Porous materials with multiple hierarchy levels can be useful as lightweight engineering structures, biomedical implants, flexible functional devices, and thermal insulators. Numerous routes have integrated bottom-up and top-down approaches for the generation of engineering materials with lightweight nature, complex structures, and excellent mechanical properties. It nonetheless remains challenging to generate ultralight porous materials with hierarchical architectures and multi-functionality. Here, the combined strategy based on Pickering emulsions and additive manufacturing leads to the development of ultralight conducting polymer foams with hierarchical pores and multifunctional performance. Direct writing of the emulsified inks consisting of the nano-oxidant-hydrated vanadium pentoxide nanowires-generated free-standing scaffolds, which are stabilized by the interfacial organization of the nanowires into network structures. The following in situ oxidative polymerization transforms the nano-oxidant scaffolds into foams consisting of a typical conducting polymer-polyaniline. The lightweight polyaniline foams featured by hierarchical pores and high surface areas show excellent performances in the applications of supercapacitor electrodes, planar micro-supercapacitors, and gas sensors. This emerging technology demonstrates the great potential of a combination of additive manufacturing with complex fluids for the generation of functional solids with lightweight nature and adjustable structure-function relationships.

Liquid Transport and Real-Time Dye Purification via Lotus Petiole-Inspired Long-Range-Ordered Anisotropic Cellulose Nanofibril Aerogels

Nowadays, large-scale oriented functional porous materials have been sought after by researchers. However, regulation of the long-range uniform and oriented structures of the material remains a challenge. Herein, ultralong anisotropic cellulose nanofibril (CNF) aerogels with uniformly ordered structures of pore walls inspired by lotus petioles were constructed by applying external speeds to counterbalance the growth driving forces of ice crystals. Based on the growth law of ice crystals, the ice crystals grew at a stable rate when the applied external speed was 0.04 mm/s, ensuring the consistent orientation of the large-scale CNF aerogel. The aerogel exhibited a rapid long-range directional transport ability to different liquid solvents, delivering ethanol up to 40 mm from bottom to top within 50 s. Moreover, by introducing rectorites with good cation-exchange properties, the resulting long-range composite possessed an enhanced adsorption capacity for methylene blue. Furthermore, aerogel successfully achieved real-time dye purification at a long distance, such as fast dye adsorption or selective adsorption. This flexible and straightforward strategy of fabricating ultralong oriented CNF aerogel materials is expected to promote the development of functional aerogels in directional liquid transport and sewage treatment.

Nanofiber-reinforced bulk hydrogel: preparation and structural, mechanical, and biological properties

Alginate-based hydrogels are increasingly being used as biomaterials for tissue engineering, drug carriers, and wound dressing; however, their poor mechanical strength limits their applications. Nanofiber reinforcement is an effective method for increasing the mechanical strength of hydrogels. However, the macro preparation of nanofiber-reinforced hydrogels with a bulk structure is challenging. Herein, we describe the fabrication of nanofiber-reinforced bulk alginate hydrogel composites. The mechanical properties of hydrogels were significantly improved, and the reinforcement law of nanofiber was systematically studied. The maximum tensile stress (0.76 MPa) was obtained with 30% nanofiber content, which was 87% higher than that of pure alginate hydrogel. The compressive stress of the composite hydrogel exhibited "J-curve" behavior with gradually increasing nanofiber content, which indicated that the composited hydrogels were suitable as biomaterials. Furthermore, in 2 h, the hydrogels killed more than 90% of the bacteria that were present, and the bacteriostatic rate reached 100% after 12 h of treatment. More importantly, the sterile environment continued to be maintained, and the composited hydrogel also had satisfactory cytocompatibility and cell adhesion. Compared with pure alginate hydrogel, the roughness of the composited hydrogel surface was increased, which resulted in stronger cell adhesion. Therefore, the composite hydrogel demonstrated improved mechanical and biological properties, and exhibited the potential for clinical application.

Solvothermal preparation of luminescent zinc(II) and cadmium(II) coordination complexes based on the new bi-functional building block and photo-luminescent sensing for Cu2+, Al3+ and L-lysine

In industry, over usage of Cu²⁺ and Al³⁺ will lead to toxic wastewater, which further to give serious pollution for the environment. On the other hand, L-lysine can enhance serotonin release in the amygdala, with subsequent changes in psychobehavioral responses to stress. Therefore it is the urgent problem to design a method for detecting the amount of Cu²⁺, Al³⁺, and L-lysine. In this work, through the solvothermal synthesis method, two new coordination complexes based on the new bifunctional building block 4'-(1H-1,2,4-triazole-1-yl)- [1,1'-biphenyl]-4-carboxylic acid (HL) have been synthesized, namely, [Zn(L)₂·4H₂O] (complex 1) and [Cd(L)₂·4H₂O] (complex 2). X-ray single-crystal diffractometer was used to analyze its structure, powder X-ray diffraction (PXRD) patterns confirmed that 1 and 2 powder's purity and 1 can keep stable during the detection process of Cu²⁺, Al³⁺, and L-lysine, respectively. Elemental analysis, thermogravimetric analysis, infrared analysis, ultraviolet analysis and fluorescent spectrum have been used to characterize these complexes. The photo-luminescent test showed that 1 can accurately recognize Al³⁺ and Cu²⁺ among various cations. On the other hand, 1 can distinguish L-lysine among amino acid molecules. Therefore, 1 can be utilized as a multifunctional fluorescent probe for Al³⁺(K_sv = 1.5570 × 10⁴ [M]^-1), Cu²⁺(K_sv = 1.4948 × 10⁴ [M]^-1) and L-lysine (K_sv = 4.9118 × 10⁴ [M]^-1) with low detection limits (17.5 μM, 18.2 μM, 5.6 μM) respectively.

Structural design toward functional materials by electrospinning: A review

Electrospinning as one of the most versatile technologies have attracted a lot of scientists’ interests in past decades due to its great diversity of fabricating nanofibers featuring high aspect ratio, large specific surface area, flexibility, structural abundance, and surface functionality. Remarkable progress has been made in terms of the versatile structures of electrospun fibers and great functionalities to enable a broad spectrum of applications. In this article, the electrospun fibers with different structures and their applications are reviewed. First, several kinds of electrospun fibers with different structures are presented. Then the applications of various structural electrospun fibers in different fields, including catalysis, drug release, batteries, and supercapacitors, are reviewed. Finally, the application prospect and main challenges of electrospun fibers are discussed. We hope that this review will provide readers with a comprehensive understanding of the structural design and applications of electrospun fibers in different fields.

Reopening dentistry after COVID-19: Complete suppression of aerosolization in dental procedures by viscoelastic Medusa Gorgo

The aerosol transmissibility of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has impacted the delivery of health care and essentially stopped the provision of medical and dental therapies. Dentistry uses rotary, ultrasonic, and laser-based instruments that produce water-based aerosols in the daily, routine treatment of patients. Abundant aerosols are generated, which reach health care workers and other patients. Viruses, including SARS-CoV-2 virus and related coronavirus disease (COVID-19) pandemic, continued expansion throughout the USA and the world. The virus is spread by both droplet (visible drops) and aerosol (practically invisible drops) transmission. The generation of aerosols in dentistry-an unavoidable part of most dental treatments-creates a high-risk situation. The US Centers for Disease Control and The Occupational Safety and Health Administration consider dental procedures to be of "highest risk" in the potential spreading of SARS-CoV-2 and other respiratory viruses. There are several ways to reduce or eliminate the virus: (i) cease or postpone dentistry (public and personal health risk), (ii) screen patients immediately prior to dental treatment (by appropriate testing, if any), (iii) block/remove the virus containing aerosol by engineering controls together with stringent personal protective equipment use. The present work takes a novel, fourth approach. By altering the physical response of water to the rotary or ultrasonic forces that are used in dentistry, the generation of aerosol particles and the distance any aerosol may spread beyond the point of generation can be markedly suppressed or completely eliminated in comparison to water for both the ultrasonic scaler and dental handpiece.

High-density Fibrous Polyimide Sponges with Superior Mechanical and Thermal Properties

A relatively low compressive strength significantly limits the practical application of sponges made from electrospun fibers because of an ultralow density <10 mg/cm³. To solve this problem, fibrous polyimide sponges with high density (HDPISG) were prepared using a "self-gluing" concept. The HDPISG have a density of up to 280 mg/cm³ and porosity >80%, and showed good breathability. The compressive strength increased significantly as the sponge densities increased. The HDPISG with a density of 280 mg/cm³ has the highest compressive strength of 5190 and 35,900 kPa under 50 and 80% compression, respectively. The small HDPISG can even hold weights more than ten thousand times of the weight of the sponge. The HDPISG also possess excellent mechanical properties after thermal treatments and no loss of compressive strength can be seen after heating at 300 °C for 30 h. Further study indicates that the HDPISG can maintain their main shape after carbonization.

Biomass-derived composite aerogels with novel structure for removal/recovery of uranium from simulated radioactive wastewater

With the development of nuclear energy, the removal/recovery of radionuclides has attracted increasing attention. Here, an ultra-light, super-elastic, konjac glucomannan/graphene oxide composite aerogel (KGCA) as a high performance adsorbent for radionuclide removal/recovery was fabricated by a three-step process of freeze-casting, freeze-drying, and carbonization. The as-prepared bionic structured KGCA showed ultralow density, high specific surface area, desirable super-elasticity, and abundant oxygen-containing functional groups. Batch adsorption results demonstrated the maximum adsorption capacity of uranium (U(VI)) on KGCA is as high as 513.4 mg g^-1, far exceeding other biomass carbon aerogels. Furthermore, KGCA showed good radiation stability, selective adsorption of U(VI), and high recycling performance. The KGCA also showed good adsorption properties even under simulated seawater or high salt concentration. Thus, these ultra-light and super-elastic biomass-derived composite aerogels could have a wide range of applications for nuclear wastewater treatment in the future.

Preparation of electrospun nanofibers with desired microstructures using a programmed three-dimensional (3D) nanofiber collector

The traditional electrospinning process produces dense two-dimensional (2D) nanofiber (NF) sheets that limit cell infiltration and proliferation. Our previous study demonstrated that 3D NF sheets could be formed on an NF collector surface mounted with multiple movable needles through the corona discharge. In this study, we developed a programmed electrospun 3D NF collector. It can precisely control the moving speed of NF collector during electrospinning; thereby fabricating 3D NFs with desired microstructures (pore size, pore volume, and interconnectivity). Four types of polycaprolactone (PCL) 3D NF matrices with different microstructures can be obtained concurrently on the NF collector surface, which are set by different forward moving speed of the NF collector device: NF-zero (no move, as control), NF-low (0.085 mm/min), NF-mid (0.158 mm/min) and NF-high (0.232 mm/min). A linear increase of the NF sheet thickness (from 0.21 mm to 0.91 mm) was recorded with accelerating collector movement. Quantitative analysis using scanning electron microscopy (SEM), micro-computed tomography (μ-CT), and confocal laser scanning microscopy (CLSM) showed a monotonic increase of pore size and porosity with the increase of collector moving speeds. The collector movement also impacted the crystallinity and mechanical properties of the NFs. When prepared at high collector speed, the NFs showed improved proliferation and differentiation (p < .05) of pre-osteoblastic MC3T3 cells compared to the NFs from the static collector. A programmed NF collector device allows for the reproducible, precise and continuous fabrication of 3D NFs with tailorable geometry and microstructures. This simple, controllable, one-step process could promote the clinical translation of electrospun NFs in tissue engineering and regenerative medicine.

Virtually Wall-Less Tubular Sponges as Compartmentalized Reaction Containers

Sponges are open cellular materials with numerous interesting features. However, the potential of compartmentalized sponges has not been explored although many new properties and applications could be envisioned. We found that compartmentalized fibrous ultraporous polymer sponges with superhydrophobic surfaces could be designed as virtually wall-less reaction containers. With this, for example, the efficient removal of CO₂ from water and the controlled mineralization of calcium carbonate are possible. The high porosity (>99%) and superhydrophobicity make these sponges ideal candidates to hold alkanolamine solution for absorbing CO₂ and exchange gas through the walls of the sponges. The tubular sponge exhibits a much higher evaporation rate than a glass tube with the same diameter due to the much larger contact area between water and air. Therefore, the spongy reaction container also possesses a much faster adsorption rate, smaller equilibration time and higher efficiency for CO₂ adsorption than the glass tube container. In addition, these tubular sponges are also utilized to precipitate calcium carbonate by ammonium carbonate decomposition, which can control the deposition rates and products by tailoring the porosity and surface chemistry in the future. These new sponges provide an ideal basis for numerous new applications, for example, as breathable pipe lines for gas-liquid exchange, slag slurry carbonization, humidifier, and blood enricher.

Wolf-Lamb-type Catalysis in One Pot Using Electrospun Polymeric Catalyst Membranes

Multistep catalytic transformations using incompatible catalysts (Wolf-Lamb-type) in a one-pot reaction cascade require site isolation of different catalysts by compartmentalization. In this work, the use of different electrospun catalytic membranes in a modular way as individual compartments is shown for one-pot Wolf-Lamb-type reaction cascades. The data are presented for one-pot cascade reaction sequences catalyzed by acidic and basic membranes made by electrospinning polymeric acid (poly(styrene-co-styrene sulfonic acid-co-4-methacryloyl-oxybenzophen)) and basic (poly(styrene-co-4-vinylpyridine-co-4-methacryloyl-oxybenzophen)) catalysts, respectively. The two-step, one-pot system used is the acidic catalyzed deacetylation of dimethoxybenzylacetale to benzaldehyde, which reacts with ethyl cyanoformate to result in a high yield of product (over 90%) under base-catalyzed conditions. The reaction kinetics are further monitored and evaluated by using differential equations, showing the necessity of a parameter Δt to represent a retarded start for the second reaction step. The concept provides an easy and upscalable approach for use in Wolf-Lamb-type systems.

Electrospinning and Electrospun Nanofibers: Methods, Materials, and Applications

Electrospinning is a versatile and viable technique for generating ultrathin fibers. Remarkable progress has been made with regard to the development of electrospinning methods and engineering of electrospun nanofibers to suit or enable various applications. We aim to provide a comprehensive overview of electrospinning, including the principle, methods, materials, and applications. We begin with a brief introduction to the early history of electrospinning, followed by discussion of its principle and typical apparatus. We then discuss its renaissance over the past two decades as a powerful technology for the production of nanofibers with diversified compositions, structures, and properties. Afterward, we discuss the applications of electrospun nanofibers, including their use as "smart" mats, filtration membranes, catalytic supports, energy harvesting/conversion/storage components, and photonic and electronic devices, as well as biomedical scaffolds. We highlight the most relevant and recent advances related to the applications of electrospun nanofibers by focusing on the most representative examples. We also offer perspectives on the challenges, opportunities, and new directions for future development. At the end, we discuss approaches to the scale-up production of electrospun nanofibers and briefly discuss various types of commercial products based on electrospun nanofibers that have found widespread use in our everyday life.

Programmable soft robotics based on nano-textured thermo-responsive actuators

Soft robotic systems are increasingly emerging as robust alternatives to conventional robotics. Here, we demonstrate the development of programmable soft actuators based on volume expansion/retraction accompanying liquid-vapor phase transition of a phase-change material confined within an elastomer matrix. The combination of a soft matrix (a silicone-based elastomer) and an embedded ethanol-impregnated polyacrylonitrile nanofiber (PAN NF) mat makes it possible to form a sealed compound device that can be operated by changing the actuator temperature above/below the boiling point of ethanol. The thermo-responsive actuators based on this principle demonstrate excellent bending ability at a sufficiently high temperature (>90 °C) - comparable with compressed air-based soft actuators. The actuator using the mechanism presented here is easy to manufacture and automate and is recyclable. Finally, the actuation mechanism can be incorporated into a wide variety of shapes and configurations, making it possible to obtain tunable and programmable soft robots that could have a wide variety of industrial applications.

A Sandwich-Structured Piezoresistive Sensor with Electrospun Nanofiber Mats as Supporting, Sensing, and Packaging Layers

Electrospun nanofiber mats have been used as sensing elements to construct piezoresistive devices due to their large surface area and high porosity. However, they have not been utilized as skin-contact supporting layers to package conductive nanofiber networks for the fabrication of piezoresistive sensors. In this work, we developed a sandwich-structured pressure sensor, which can sensitively monitor human motions and vital signs, with electrospun nanofiber mats as supporting, sensing, and packaging layers. The nanofiber mats were prepared by electrospinning with biocompatible poly (l-lactide) (PLA), silk fibroin (SF), and collagen (COL) as raw materials. The synthesized PLA–SF–COL mat possesses a non-woven structure with a fiber diameter of 122 ± 28 nm and a film thickness of 37 ± 5.3 μm. Polypyrrole (PPy) nanoparticles were grown in-situ on the mat to form a conductive layer. After stacking the pristine and conductive mats to form a PLA–SF–COL mat/(PPy-coated mat)₂ structure, another layer was electrospun to pack the multilayers for the construction of a sandwich-structured piezoresistive sensor. The as-prepared device can sensitively detect external pressures caused by coin loading and finger tapping/pressing. It can also tolerate more than 600 times of pressing without affecting its sensing capability. The human body-attached experiments further demonstrate that the sensor could real-time monitor finger/arm bending, arterial pulse, respiration rate, and speaking-caused throat vibration. The electrospinning-based fabrication may be used as a facile and low-cost strategy to produce flexible piezoresistive sensors with excellent skin-compatibility and great pressure sensing capability.

Multi-Jet Electrospinning with Auxiliary Electrode: The Influence of Solution Properties

Multiple jets ejection in electrospinning has been a major approach to achieving a high production rate of ultrafine fibers, also known as nanofibers. This work studies the effect of solution parameters—including dielectric constant, polarity, conductivity and surface tension—on the jet number and jet evolution in the auxiliary electrode electrospinning approach. The results show that it is easier to generate 2–6 jets with short stable jet length (1.7–6.9 mm) under low voltage (5.03–7.13 kV) when solutions have higher dielectric constant (32.2–78.6) and larger surface tension (31.8–41.29 mN/m). The influence of solution properties on stable jet length and the influence of applied voltage to produce multiple jets are discussed in detail. This work provides a new perspective for understanding jet evolution and mass production of nanofibers in electrospinning.

Ultraporous, Compressible, Wettable Polylactide/Polycaprolactone Sponges for Tissue Engineering

Ultraporous, degradable sponges made of either polylactide or of blends of polylactide/poly(ε-caprolactone) are prepared by freeze-drying of dispersions of short electrospun fibers and subsequent thermal annealing. The sponges feature ultrahigh porosity (99.6%), a hierarchical cellular structure, and high reversible compressibility with fast recovery from deformation in the dry as well as in the wet state. The sponge properties depend on the fiber dispersion concentration and the annealing temperature. Sponge characteristics like fiber density (2.5-20 mg/cm³), size, shape, crystallinity, mechanical strength, wetability, and structural integrity are user adjustable. Cell culture experiments were successfully performed with Jurkat cells with Confocal Laser Scanning Microscopy and MTT staining showing rapid cell proliferation. Live/Dead staining demonstrated high viability of the seeded cells. The sponge characteristics and modifications investigated and presented here reveal that these sponges are highly promising for tissue engineering applications.

Exploration of Ultralight Nanofiber Aerogels as Particle Filters: Capacity and Efficiency

Ultralight nanofiber aerogels (NFAs) or nanofiber sponges are a truly three-dimensional derivative of the intrinsically flat electrospun nanofiber mats or membranes (NFMs). Here we investigated the potential of such materials for particle or aerosol filtration because particle filtration is a major application of NFMs. Ultralight NFAs were synthesized from electrospun nanofibers using a solid-templating technique. These materials had a tunable hierarchical cellular open-pore structure. We observed high filtration efficiencies of up to 99.999% at the most penetrating particle size. By tailoring the porosity of the NFAs through the processing parameters, we were able to adjust the number of permeated particles by a factor of 1000 and the pressure drop by a factor of 9. These NFAs acted as a deep-bed filter, and they were capable of handling high dust loadings without any indication of performance loss or an increase in the pressure drop. When the face velocity was increased from 0.75 to 6 cm s^-1, the filtration efficiency remained high within a factor of 1.1-10. Both characteristics were in contrast to the behavior of two commercial NFM particle filters, which showed significant increases in the pressure drop with the filtration time as well as a susceptibility against high face velocities by a factor of 105.

Electrospun nanofiber reinforced composites: a review

High performance electrospun nanofibers could be used to fabricate nanofiber reinforced composites.

Low-Density Open Cellular Sponges as Functional Materials

Low-density macroporous sponges with densities less than 100 mg cm^-3 are both a challenge and an opportunity for advanced chemistry and material science. The challenge lies in the precise preparation of the sponges with property combinations that lead to novel applications. Bottom-up and top-down chemical and engineering methods for the preparation of sponges are a major focus of this Review, with an emphasis on carbon and polymer materials. The light weight, sustainability, breathability, special wetting characteristics, large mass transfer, mechanical stability, and large pore volume are typical characteristics of sponges made of advanced materials and could lead to novel applications. Some selected sponge properties and potential applications are discussed.

Exploration of the Electrical Conductivity of Double-Network Silver Nanowires/Polyimide Porous Low-Density Compressible Sponges

Stress-responsive, highly flexible, and breathable nanocomposite sponges show an electrical conductivity from 1.7 to 166.6 S/cm depending on the applied stress. Key for the responsive electrical conductivity of the sponges is the change of percolation of the silver nanowires. These sponges made of short electrospun fibers and silver nanowires could be applied without any amplifier for the operation of automobile bulbs and as an efficient Joule heater. The time required for electric heating (current on) and cooling is very short. Interestingly, the maximum temperature reached by electric heating depends on the compression status. The higher the compression status, the lower is the maximum temperature, which is in accordance with the understanding of Joule heaters. It is noteworthy that these sponges are thermally, chemically, and mechanically very stable. These conductive sponges will open a new area for novel conductive devices with relevance for real-world applications.

Ultralight, Thermally Insulating, Compressible Polyimide Fiber Assembled Sponges

Tunable density, thermally and mechanically stable, elastic, and thermally insulating sponges are required for demanding applications. Hierarchically structured sponges with bimodal interconnected pores, porosity more than 99%, and tunable densities (between 7.6 and 10.1 mg/cm³) are reported using polyimide (PI) as high temperature stable polymer. The sponges are made by freeze-drying a dispersion of short PI fibers and precursor polymer, poly(amic acid) (PAA). The concept of "self-gluing" the fibrous network skeleton of PI during sponge formation was applied to achieve mechanical stability without sacrificing the thermal properties. The sponges showed initial degradation above 400 and 500 °C in air and nitrogen, respectively. They have low thermal conductivity of 0.026 W/mK and thermal diffusivity of 1.009 mm²/s for a density of 10.1 mg/cm³. The sponges are compressible for at least 10 000 cycles and good thermal insulators even at high compressions. These fibrous PI sponges are promising candidates for potential applications in thermal insulation, lightweight construction, high-temperature filtration, sensors, and catalyst carrier for high-temperature reactions.

Exploration of Macroporous Polymeric Sponges As Drug Carriers

Achieving high drug loading capacity and controlling drug delivery are two main challenges related to drug carriers. In this study, polymeric macroporous sponges with very high pore volume and large porosity are introduced as a new-type of drug carrier. Due to the high pore volume (285 and 166 cm³/g for the sponges with densities of 3.5 and 6.0 mg/cm³, respectively), the sponges exhibit very high drug loading capacities with average values of 1870 ± 114 and 2697 ± 73 mg/g in the present study, which is much higher than the meso and microporous drug carriers (<1500 mg/g). In order to control the release profiles, an additional poly(p-xylylene) (PPX) coating was deposited by chemical vapor deposition on the drug loaded sponge. Consequently, Artemisone (ART) release in the aqueous medium could be retarded, depending on the density of the sponge and the thickness of the coating. In future, the new 3D polymeric sponges would be highly beneficial as drug carriers for the programmed release of drugs for treatment of chronic diseases.

Spongy Gels by a Top-Down Approach from Polymer Fibrous Sponges

Ultralight cellular sponges offer a unique set of properties. We show here that solvent uptake by these sponges results in new gel-like materials, which we term spongy gels. The appearance of the spongy gels is very similar to classic organogels. Usually, organogels are formed by a bottom-up process. In contrast, the spongy gels are formed by a top-down approach that offers numerous advantages for the design of their properties, reproducibility, and stability. The sponges themselves represent the scaffold of a gel that could be filled with a solvent, and thereby form a mechanically stable gel-like material. The spongy gels are independent of a time-consuming or otherwise demanding in situ scaffold formation. As solvent evaporation from gels is a concern for various applications, we also studied solvent evaporation of wetting and non-wetting liquids dispersed in the sponge.