Nanocomposites prepared by electrohydrodynamics and their drug release properties

Synergetic effects of tetracycline hydrochloride incorporated regenerated cellulose acetate - Bacterial cellulose hybrid nanocomposite: Potential in biomedical application

Litter from cigarette waste is a significant threat to organisms and ecosystems. However, this waste contains cellulose acetate (CA) that can be recycled into raw materials. In this study, recycled CA from cigarettes (CFCA) electrospun through electro-spinning technique and developed hybrid nanocomposite by incorporating CFCA in the fermentation media, followed by self-assembly of bacterial cellulose (BC). CFCA exhibit excessive hydrophobicity due to their high crystallinity and reorientation of hydrophobic groups. We aimed to improve the hydrophilic, thermal and mechanical properties of CFCA. We examined fiber morphology using a scanning electron microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction Analysis (XRD), thermogravimetric analysis (TGA), swelling capacity and mechanical properties. BC/CFCA showed higher swelling capacity, improved thermal properties, and good tensile strength compared to CFCA. Additionally, tetracycline hydrochloride (TC) was loaded into developed BC/CFCA matrix and evaluated in-vitro drug release, antibacterial activity and cytotoxicity. In-vitro drug release results showed that developed BC/CFCA can able to control TC release. In addition, prepared BC/CFCA-TC composites demonstrated excellent antibacterial activity against gram-positive and gram-negative bacteria. More importantly, BC/CFCA-TC composites exhibit good cytotoxicity on mouse fibroblast cells (L929). These characteristics of BC/CFCA-TC membranes indicate they may successfully serve as wound dressings and other medical biomaterials.

Regeneration and modification of cellulose acetate from cigarette waste: Biomedical potential by encapsulation of tetracycline hydrochloride

Cigarette waste are pervasive litter on Earth, posing a major threat to organisms and ecosystems. However, these waste contain cellulose acetate (CA) and can be recycled, transforming into raw materials for new products. Polymers like CA can be used in biomedical applications as drug carriers and scaffolds for drug release. In this study, cigarette filters waste was collected, recycled and used for fabricating the nanofibrous membrane of cellulose acetate nanofibers (CFCA) through electrospinning technique. Tetracycline hydrochloride (TC) was encapsulated in the nanofibers to prevent bacterial infections. Various analyses were conducted: Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction Analysis (XRD) and Thermogravimetric analysis (TGA). CA and CFCA exhibited high water uptake properties and exhibited similar breaking stress and strain values. Both CA and CFCA effectively acted as stable drug carriers, with sustained in vitro drug release. Antibacterial activity was demonstrated by the drug-loaded CA and CFCA nanofibers against, Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli. Based on their cytotoxicity evaluations on mouse fibroblast cells (L929), CA and CFCA fibrous mats demonstrated no cytotoxicity and similar cell viability results. Consequently, the TC-loaded nanofibers made from CA and CFCA exhibited suitable properties for wound healing applications.

Fabrication of hierarchical porous ethyl cellulose fibrous membrane by electro-centrifugal spinning for drug delivery systems with excellent integrated properties

Drug delivery systems (DDSs) based on micro-and nano- fibrous membrane have been developed for decades, in which great attention has been focused on achieving controlled drug release. However, the study on the integrated performance of these drug-loaded membranes in the use of in-vitro drug delivery dressing is lacking, as clinical medication also needs consideration from the perspectives of wound safety and patient convenience. Herein, a trilayered hierarchical porous ethyl cellulose (EC) fibrous membrane based DDS (EC-DDS) was developed by electro-centrifugal spinning. Significantly, the hierarchical porous structure of the EC-DDSs with high specific surface area (34.3 m²g^-1) and abundant long-regulative micro-and nano- channels demonstrated its merits in improving the hydrophobicity (long-term splash resistance (CA > 130°) and prolonging the drug release (the release time of ~80 % tetracycline hydrochloride (TCH) prolonged from 10 min to 24 h). Meanwhile, the trilayered EC-DDS also revealed excellent biocompatibility, antibacterial activity, air permeability, moisture permeability, water absorption capacity, mechanical strength, and flexibility. With these excellent integrated features, the EC-DDS could prevent external fluids, avoid infection, and provide comfort. Furthermore, this work also provides a new guide for the high-efficiency fabrication of porous fibrous membranes.

Hydrogel transformed from sandcastle-worm-inspired powder for adhering wet adipose surfaces

Normally, hydrogel adhesives do not perform well on adipose matters that are covered with bodily fluids. Besides, the maintenance of high extensibility and self-healing ability in fully swollen state still remains challenging. Based on these concerns, we reported a sandcastle-worm-inspired powder, which was made of tannic acid-functionalized cellulose nanofiber (TA-CNF), polyacrylic acid (PAA) and polyethyleneimine (PEI). The obtained powder can rapidly absorb diverse bodily fluids and transform into a hydrogel, displaying fast (＜3 s), self-strengthening and repeatable wet adhesion to adipose tissues. Due to the dense physically cross-linked network, the formed hydrogel still showed excellent extensibility (∼14 times) and self-healing ability after being immersed in water. Moreover, excellent hemostasis, antibacterial ability and biocompatibility make it suitable for numerous biomedical applications. With combined advantages of powders and hydrogels, such as good adaptability to irregular sites, efficient drug loading capacity and tissue affinity, the sandcastle-worm-inspired powder offers significant promise as tissue adhesive and repair materials. This work may open new avenues for designing high-performance bioadhesives with efficient and robust wet adhesiveness to adipose tissues.

Production of nanostructured systems: Main and innovative techniques

In the constant search for the development of more-specific and more-selective drugs, especially with regard to the challenge of encapsulating hydrophilic molecules, polymer nanotechnologies are remarkable for their biocompatible and biodegradable properties. The most-used nanoencapsulation methods consist of emulsification procedures, where emulsified droplets of a given polymer and drug solidify into nanoparticles after solvent extraction from the polymeric phase. This review introduces conventional emulsification methods but also highlights new emulsification technologies such as microfluidics, membrane emulsification and other techniques, including spray drying, inkjet printing and electrospraying.

Physicomechanical properties and in vitro release behaviors of electrospun ibuprofen-loaded blend PEO/EC fibers

Electrospinning is a fiber manufacturing technique with the possibility of encapsulating high levels of small molecule drugs while providing controlled release rates. In this study, electrospun blend fibers were produced from polyethylene oxide (PEO) and ethyl cellulose (EC) at various compositions to encapsulate a poorly water-soluble drug of ibuprofen (IBP) at 30% loading. Microscopic evaluation showed smooth and defect-free fiber morphologies for blank and IBP-loaded PEO/EC fibers. The average fiber diameters and fiber yields suggested a potential optimization on the blend fiber composition for the electrospun drug-eluting PEO/EC fibers, where the highest average fiber diameter and fiber yield occurred at 50PEO/50EC fiber composition. Surface wettability studies demonstrated the effects on surface hydrophobicity from blend fibers of water-soluble PEO and hydrophobic EC as well as the incorporation of IBP. In addition, blend fibers containing more PEO promoted the water absorption rates through dissolution of the polymer matrix. Furthermore, results from mechanical testing of the blend fibers showed the highest fiber elastic modulus and tensile strength at fiber compositions in between 75PEO/25EC and 50PEO/50EC, corresponding to the average fiber diameter measurements. The in vitro IBP release rates demonstrated a dependence on the EC compositions supported by the surface wettability and water absorption rate studies. In general, our work demonstrated the ability to electrospin blank and IBP-loaded PEO/EC fibers with the scientific understandings of EC compositions on modulations of fiber physicomechanical properties and in vitro drug release rates. The findings from the work indicated the potential engineering and pharmaceutical applications of electrospun drug-eluting fibers for topical drug delivery.

Nature-Inspired Hydrogel Network for Efficient Tissue-Specific Underwater Adhesive

Underwater adhesives with efficient, selective, and repeatable adhesion are urgently needed for biomedical applications. Catechol-containing hydrogel adhesives have aroused much interest, but the design of specific underwater adhesives to biotic surfaces is still a challenge. Here we report a facile way that recapitulates the adhesion mechanism of mussel and sea gooseberry for the development of robust and specific hydrogel adhesives. With an exquisite design of chemical bonding, catechol chemistry, and electrostatic interaction, the hydrogel consisting of poly(acrylic acid) grafted with N-hydroxysuccinimide ester (PAA-NHS ester), tea polyphenol (TP), chitosan (CS), and Al³⁺ exhibited fast, specific, and repeatable underwater adhesion to various biological tissues, such as porcine skin, intestine, liver, and shrimp. Furthermore, nanofibers-hydrogel composite (NF-HG) was prepared via the wicking effect of curcumin-loaded electrospun nanofibers. The NF-HG exhibited pH-responsive color changing properties, sustained drug release, and good cell viability, which made it suitable as a novel wound healing material. This strategy may provide great inspiration for designing multifunctional specific underwater adhesives.

Bioactive Icariin/β-CD-IC/Bacterial Cellulose with Enhanced Biomedical Potential

A "super" bioactive antibacterial hydrogel, Icariin-β-CD-inclusion complex/Bacterial cellulose and an equally capable counterpart Icariin-Bacterial cellulose (ICBC) were successfully produced with excellent antioxidant properties. The highly porous hydrogels demonstrated very high fluid/liquid absorption capability and were functionally active as Fourier Transform Infrared Spectrometer (FTIR) test confirmed the existence of abundant hydroxyls (-OH stretching), carboxylic acids (-CH₂/C-O stretching), Alkyne/nitrile (C≡C/C≡N stretching with triple bonds) and phenol (C-H/N-O symmetric stretching) functional groups. Scanning electron microscope (SEM) and X-ray diffraction (XRD) tests confirmed a successful β-CD-inclusion complexation with Icariin with a great potential for sustained and controlled drug release. In vitro drug release test results indicated a systemic and controlled release of the drug (Icariin) from the internal cavities of the β-CD inclusion complex incorporated inside the BC matrix with high Icariin (drug) release rates. Impressive inactivation rates against Gram-negative bacteria Escherichia coli ATCC 8099 and gram-positive bacteria Staphylococcus aureus ATCC 6538; >99.19% and >98.89% respectively were recorded, as the materials proved to be non-toxic on L929 cells in the in vitro cytotoxicity test results. The materials with promising versatile multipurpose administration of Icariin for wound dressing (as wound dressers), can also be executed as implants for tissue regeneration, as well as face-mask for cosmetic purposes.

A plant-inspired long-lasting adhesive bilayer nanocomposite hydrogel based on redox-active Ag/Tannic acid-Cellulose nanofibers

Long-lasting and reusable adhesive hydrogels are highly desirable in biomedical and relevant applications, however, its design still remains challenge. Here, a series of plant-inspired adhesive hydrogels were prepared based on Ag/Tannic acid-Cellulose nanofibers (Ag/TA-CNF) triggered reversible quinone/catechol chemistry, which mimicked the long-lasting reductive/oxidative balance in mussels. The dynamic redox system generated catechol groups inner the hydrogel continuously, imparting hydrogels with high and repeatable adhesiveness. Besides, the hydrogel still maintained its high adhesiveness after storing at extreme temperatures for 30 days. Furthermore, to broaden the biomedical applications of the hydrogels, the pre-gel solution with optimal composition was cast onto the surface of vaccarin-loaded electrospun nanofibers to form the bilayer nanocomposite hydrogel (NF@HG) in situ. The NF@HG with the intrinsic properties of the hydrogel layer (e.g. stretchable, adhesive, antioxidant, antifreezing, antidrying, photothermal and antibacterial) exhibited enhanced mechanical properties, sustained drug release and good cytocompatibility, which could be an attractive candidate for wound healing material. Taken together, this study may inspire new aspects for designing reusable and long-lasting adhesive hydrogels according to dynamic catechol chemistry.

Air-jet spinning corn zein protein nanofibers for drug delivery: Effect of biomaterial structure and shape on release properties

Nanofiber materials are commonly used as delivery vehicles for dermatological drugs due to their high surface-area-to-volume ratio, porosity, flexibility, and reproducibility. In this study air-jet spinning was used as a novel and economic method to fabricate corn zein nanofiber meshes with model drugs of varying solubility, molecular weight and charge. The release profiles of these drugs were compared to their release from corn zein films to elucidate the effect of geometry and structure on drug delivery kinetics. In film samples, over 50% of drug was released after only 2 h. However, fiber samples exhibited more sustained release, releasing less than 50% after one day. FTIR, SEM, and DSC were performed on nanofibers and films before and after release of the drugs. Structural analysis revealed that the incorporation of model drugs into the fibers would transform the zein proteins from a random coil network to a more alpha helical structure. Upon release, the protein fiber reverted to its original random coil network. In addition, thermal analysis indicated that fibers can protect the drug molecules in high temperature above 160 °C, while drugs within films will degrade below 130 °C. These findings can likely be attributed to the mechanical infiltration of the drug molecules into the ordered structure of the zein fibers during their solution fabrication. The slow release from fiber samples can be attributed to this biophysical interaction, illustrating that release is dictated by more than diffusion in protein-based carriers. The controlled release of a wide variety of drugs from the air-jet spun corn zein nanofiber meshes demonstrates their success as drug delivery vehicles that can potentially be incorporated into different biological materials in the future.

Hierarchical porous nanofibers containing thymol/beta-cyclodextrin: Physico-chemical characterization and potential biomedical applications

As an effective natural antibacterial component, the low water solubility of thymol (THY) has stemmed its potential in biomedical application. Here, β-cyclodextrin (β-CD) and THY were self-assembled to form water-soluble inclusion complex (IC). The successful formation of IC was confirmed via ¹H NMR. As an antibacterial agent, the resultant IC was then incorporated into cellulose acetate (CA) fibrous matrix with hierarchical structure (nanopores on porous fibrous webs) via electrospinning (CA/THY/β-CD), and the pure THY was also encapsulated into CA for comparison (CA/THY). In vitro dissolution tests demonstrated that CA/THY/β-CD fibrous membrane exhibited sustained drug release, which abided by non-Fickian diffusion. Besides, the CA/THY/β-CD fibrous membrane exhibited more effective and long-lasting antibacterial activity against S. aureus. Furthermore, the combination of hierarchical porous structure with sustained drug release endowed the CA/THY/β-CD fibrous membrane with good cytocompatibility. Taken together, the CA/THY/β-CD fibrous membrane could be an attractive candidate for wound dressing material.

Preparation, Characterization and Properties of Porous PLA/PEG/Curcumin Composite Nanofibers for Antibacterial Application

Polylactide/polyethylene glycol/curcumin (PLA/PEG/Cur) composite nanofibers (CNFs) with varying ratios of PEG were successfully fabricated by electrospinning. Characterizations of the samples, such as the porous structure, crystalline structure, pore size, wetting property and Cur release property were investigated by a combination of scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and UV spectrophotometer. The antibacterial properties of the prepared porous CNFs against Escherichia coli bacteria were studied. The results showed that with the decrease of PEG in the CNFs, there appeared an evident porous structure on the CNF surface, and the porous structure could enhance the release properties of Cur from the CNFs. When the weight ratio (PEG:PLA) was 1:9, the pore structure of the nanofiber surface became most evident and the amount of Cur released was highest. However, the antibacterial effect of nonporous CNFs was better due to burst release over a short period of time. That meant that the porous structure of the CNFs could reduce the burst release and provide better control over the drug release.