Effect of blending HA-g-PLLA on xanthohumol-loaded PLGA fiber membrane

Fabrication of Magnetic Poly(L-lactide) (PLLA)/Fe3O4 Composite Electrospun Fibers

Electrospinning technology is widely used for preparing biological tissue engineering scaffolds because of its advantages of simple preparation, accurate process parameters, and easy control. Poly(L-lactide) (PLLA) is regarded as a promising biomass-based polymer for use in electrospinning. The incorporation of Fe3O4 nanoparticles (NPs) could improve the osteogenic differentiation and proliferation of cells in the presence or absence of a static magnetic field (SMF). In this work, these two materials were blended together to obtain electrospun samples with better dispersibility and improved magnetic properties. First, composite PLLA and Fe3O4 NP fibers were prepared by means of electrospinning. The influence of electrospinning conditions on the morphology of the composite fibers was then discussed. Changes in magnetic properties and thermal stability resulting from the use of different PLLA/Fe3O4 mass ratios were also considered. Next, the morphology, crystal state, thermodynamic properties, and magnetic properties of the electrospun samples were determined using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and vibration sample magnetization (VSM). The results showed that the fibers prepared using PLLA with Mn = 170,000 exhibited good morphology when electrospun at 12 KV. The magnetic properties of PLLA/Fe3O4 composite electrospun fibers increased with the NP content, with the exception of thermal stability. The results of the present study may help to promote the further development of PLLA/Fe3O4 composite materials in the biomedical field.

Sophorolipid-based microemulsion delivery system: Multifaceted enhancement of physicochemical properties of xanthohumol

Xanthohumol (XN) has numerous compelling physiological activities, but the poor solubility and stability severely limit its utilization. Therefore, a microemulsion (ME) delivery system based on biosurfactant sophorolipids (SLs) was established and its improvement on physicochemical properties of XN was investigated. The results showed that the systems increased the solubility of XN by about 4000 times, and its half-life during storage was extended to over 150 days. Partial replacement of Tween 80 with SL did not greatly affect their ability to form O/W subregions (in the high aqueous phase), but further improved the solubilization efficiency, storage stability, and antioxidant properties of XN. In vitro models revealed the release profile of XN from the systems followed non-Fickian diffusion, and the ME structure markedly strengthened its digestive stability and bioaccessibility. These results indicated that SL-based ME systems had great potential as a green solubilization and delivery method for XN and other hydrophobic drugs.

Polymeric Systems for the Controlled Release of Flavonoids

Flavonoids are natural compounds that are attracting great interest in the biomedical field thanks to the wide spectrum of their biological properties. Their employment as anticancer, anti-inflammatory, and antidiabetic drugs, as well as for many other pharmacological applications, is extensively investigated. One of the most successful ways to increase their therapeutic efficacy is to encapsulate them into a polymeric matrix in order to control their concentration in the physiological fluids for a prolonged time. The aim of this article is to provide an updated overview of scientific literature on the polymeric systems developed so far for the controlled release of flavonoids. The different classes of flavonoids are described together with the polymers most commonly employed for drug delivery applications. Representative drug delivery systems are discussed, highlighting the most common techniques for their preparation. The flavonoids investigated for polymer system encapsulation are then presented with their main source of extraction and biological properties. Relevant literature on their employment in this context is reviewed in relationship to the targeted pharmacological and biomedical applications.

Traditional Chinese medicine promotes bone regeneration in bone tissue engineering

Bone tissue engineering (BTE) is a promising method for the repair of difficult-to-heal bone tissue damage by providing three-dimensional structures for cell attachment, proliferation, and differentiation. Traditional Chinese medicine (TCM) has been introduced as an effective global medical program by the World Health Organization, comprising intricate components, and promoting bone regeneration by regulating multiple mechanisms and targets. This study outlines the potential therapeutic capabilities of TCM combined with BTE in bone regeneration. The effective active components promoting bone regeneration can be generally divided into flavonoids, alkaloids, glycosides, terpenoids, and polyphenols, among others. The chemical structures of the monomers, their sources, efficacy, and mechanisms are described. We summarize the use of compounds and medicinal parts of TCM to stimulate bone regeneration. Finally, the limitations and prospects of applying TCM in BTE are introduced, providing a direction for further development of novel and potential TCM.

Electrospun Fibers Derived from Peptide Coupled Amphiphilic Copolymers for Dorsal Root Ganglion (DRG) Outgrowth

Developing scaffolds with appropriate mechanical/structural features as well as tunable bioactivities are indispensable in the field of tissue engineering. This study focused on one such attempt to electrospin the copolymer of L-lactic acid (L-LA) and functional monomer (3(S)- [(benzyloxycarbony)methyl]-1,4-dioxane-2,5-dione, BMD) with small peptide modifications for the purpose of neural tissue engineering. Scanning Electron Microscopy (SEM) micrographs showed fabricated electrospun copolymer as porous and uniform nanofibrous materials with diameter in the range of 800-1000 nm. In addition, the modified scaffolds displayed a lower contact angle than poly(L-lactide) (PLLA) indicating higher hydrophilicity. To further incorporate the bioactive functions, the nanofibers were chemically coupled with small peptide (isoleucine-lysine-valine-alanine-valine, IKVAV). The incorporation of IKVAV onto the electrospun fiber was confirmed by X-ray photoelectron spectroscopy (XPS) and such incorporation did not affect the surface morphology or fiber diameters. To demonstrate the potential of applying the designed scaffolds for nerve regeneration, dorsal root ganglion (DRG) neurons were cultured on the nanofibers to examine the impact on neurite outgrowth of DRGs. The results indicated that the fabricated nanofibrous matrix with small peptide might be a potential candidate for neural tissue engineering.

Impact of Lipid/Magnesium Hydroxide Hybrid Nanoparticles on the Stability of Vascular Endothelial Growth Factor-Loaded PLGA Microspheres

The purpose of the present study is to characterize poly(d,l-lactide-co-glycolide) (PLGA) composite microcarriers for vascular endothelial growth factor (VEGF) delivery. To reduce the initial burst release and protect the bioactivity, VEGF is encapsulated in soybean l-α-phosphatidylethanolamine (PE) and l-α-phosphatidylcholine (PC) anhydrous reverse micelle (VEGF-RM) nanoparticles. Also, mesoporous nano-hexagonal Mg(OH)₂ nanostructure (MNS)-loaded PE/PC anhydrous reverse micelle (MNS-RM) nanoparticles are synthesized to suppress the induced inflammation of PLGA acidic byproducts and regulate the release profile. The flow-focusing microfluidic geometry platforms are used to fabricate different combinations of PLGA composite microspheres (PLGA-CMPs) with MNSs, MNS-RM, VEGF-RM, and native VEGF. The essential parameters of each formulation, such as release profiles, encapsulation efficacy, bioactivity, inflammatory response, and cytotoxicity, are investigated by in vitro and in vivo studies. The results indicate that generated acidic byproducts during the hydrolytic degradation process of PLGA can be buffered, and pH values inside and outside microspheres can remain steady during degradation by MNSs. Furthermore, the significant improvement in the stability of the encapsulated VEGF is confirmed by the bioactivity assay. In vitro release study shows that the VEGF initial burst release is well minimized in the present microcarriers. The present monodisperse PLGA-CMPs can be widely used in various tissue engineering and therapeutic applications.

Composites made of polyorganophosphazene and carbon nanotube up-regulating osteogenic activity of BMSCs under electrical stimulation

Bone is an electrically responsive tissue, so electroactive materials that can deliver electrical cues to bone are helpful for enhancing regeneration under electrical stimulation (ES), and conductive materials are crucial in ES transmission to determine osteogenesis. Compared with polyesters, biodegradable polyorganophosphazenes (POPPs) show superiority in the field of bone tissue engineering thanks to their rich phosphorus/nitrogen contents, suggesting that the combination of POPPs-based conductive substrates with ES may achieve synergistic enhancements on osteogenesis. Herein, conductive composite films were fabricated by blending poly[(alanine ethyl ester)-(glycine ethyl ester)]phosphazene (PAGP) with carbon nanotubes (CNTs). After surface modification with polydopamine (PDA), bone marrow mesenchymal stromal cells (BMSCs) were cultured on the films under ES, using the cells cultured on conductive films composed of poly(L-lactide) (PLLA) and CNTs as controls. The BMSCs on PAGP/CNT films demonstrated significantly faster proliferation rates and stronger osteogenic differentiation potentials than those on PLLA/CNT films, while cell attachments on the two PDA-coated substrates were similar. Under appropriate ES, further increases in the expressions of osteogenic markers as alkaline phosphatase, collagen I and calcium deposition were identified in comparison with the cases without ES. The contributions of the osteocompatible POPPs, the substrate conductivity and the ES treatment to enhanced osteogenesis suggested new strategies for the design of bone repair materials.

Microfluidic-assisted fabrication of reverse micelle/PLGA hybrid microspheres for sustained vascular endothelial growth factor delivery

In this study, poly (d, l-lactide-co-glycolide) (PLGA) composite microspheres containing anhydrous reverse micelle (R.M.) dipalmitoylphosphatidylcholine (DPPC) nanoparticles loaded vascular endothelial growth factor (VEGF) were produced using microfluidic platforms. The VEGF-loaded R.M. nanoparticles (VRM) were achieved by initial self-assembly and subsequent lipid inversion of the DPPC vesicles. The fabricated VRMs were encapsulated into the PLGA matrix by flow-focusing geometry microfluidic platforms. The encapsulation efficiency, in vitro release profile, and the bioactivity of the produced composite microspheres were investigated. The release study showed that VEGF was slowly released from the PLGA composite microspheres over 28 days with a reduced initial burst (18  ±  4.17% in the first 24 H). The VEGF stability during encapsulation and release period was also investigated, and the results indicated that encapsulated VEGF was well preserved. Also, the bioactivity assay of the PLGA composite microspheres on human umbilical vein endothelial cells was confirmed that the encapsulated VEGF was utterly active. The present monodisperse and controllable VEGF-loaded microspheres with reproducible manner could be widely used in tissue engineering and therapeutic applications.

Functional Nanofibrous Biomaterials of Tailored Structures for Drug Delivery-A Critical Review

Nanofibrous biomaterials have huge potential for drug delivery, due to their structural features and functions that are similar to the native extracellular matrix (ECM). A wide range of natural and polymeric materials can be employed to produce nanofibrous biomaterials. This review introduces the major natural and synthetic biomaterials for production of nanofibers that are biocompatible and biodegradable. Different technologies and their corresponding advantages and disadvantages for manufacturing nanofibrous biomaterials for drug delivery were also reported. The morphologies and structures of nanofibers can be tailor-designed and processed by carefully selecting suitable biomaterials and fabrication methods, while the functionality of nanofibrous biomaterials can be improved by modifying the surface. The loading and releasing of drug molecules, which play a significant role in the effectiveness of drug delivery, are also surveyed. This review provides insight into the fabrication of functional polymeric nanofibers for drug delivery.

Development of a Biocompatible PLGA Polymers Capable to Release Thrombolytic Enzyme Prourokinase

The novelty of the work lies in the creation and study of the physical and biological properties of biodegradable polymer coatings for stents based on poly(lactic-co-glycolic acid) (PLGA). Polymer coatings are capable of prolonged and directed release of molecules with a high molecular weight, in particular, protein molecules of prourokinase (m.w. 54 kDa). A technology has been developed to create coatings having a relative elongation of 40% to 165% and a tensile strength of 25-65 MPa. Coatings are biodegradable; the rate of degradation of the polymer in an isotonic solution varies in the range of 0.05%-1.0% per day. The created coatings are capable of controlled release of the protein of prourokinase, while about 90% of the molecules of prourokinase retain their enzymatic activity. The rate of release of prourokinase can vary from 0.01 to 0.08 mg/day/cm². Coatings do not have a short-term toxic effect on mammalian cells. The mitotic index of cells growing on coatings is approximately 1.5%. When implanting the developed polymers in animals in the postoperative period, there are no complications. Histological examination did not reveal pathological processes. When implanting individual polymers 60 days after surgery, only traces of PLGA are detected. Thus, a biodegradable composite mechanically resistant polymer capable of prolonged release of the high molecular weight prourokinase enzyme has been developed.

Poly(vinylidene fluoride) Composite Nanofibers Containing Polyhedral Oligomeric Silsesquioxane⁻Epigallocatechin Gallate Conjugate for Bone Tissue Regeneration

To provide adequate conditions for the regeneration of damaged bone, it is necessary to develop piezoelectric porous membranes with antioxidant and anti-inflammatory activities. In this study, composite nanofibers comprising poly(vinylidene fluoride) (PVDF) and a polyhedral oligomeric silsesquioxane–epigallocatechin gallate (POSS–EGCG) conjugate were fabricated by electrospinning methods. The resulting composite nanofibers showed three-dimensionally interconnected porous structures. Their average diameters, ranging from 936 ± 223 nm to 1094 ± 394 nm, were hardly affected by the addition of the POSS–EGCG conjugate. On the other hand, the piezoelectric β-phase increased significantly from 77.4% to 88.1% after adding the POSS–EGCG conjugate. The mechanical strength of the composite nanofibers was ameliorated by the addition of the POSS–EGCG conjugate. The results of in vitro bioactivity tests exhibited that the proliferation and differentiation of osteoblasts (MC3T3-E1) on the nanofibers increased with the content of POSS–EGCG conjugate because of the improved piezoelectricity and antioxidant and anti-inflammatory properties of the nanofibers. All results could suggest that the PVDF composite nanofibers were effective for guided bone regeneration.

Anhydrous reverse micelle lecithin nanoparticles/PLGA composite microspheres for long-term protein delivery with reduced initial burst

To address the issue of initial burst release from poly (lactic-co-glycolic) acid (PLGA) microspheres prepared by water-in-oil-in-water (W/O/W) double emulsion technique, PLGA composite microspheres containing anhydrous reverse micelle (ARM) lecithin nanoparticles were developed by a modified solid-in-oil-in-water (S/O/W) technique. Bovine serum albumin (BSA) loaded ARM lecithin nanoparticles, which were obtained by initial self-assembly and subsequent lipid inversion of the lecithin vesicles, were then encapsulated into PLGA matrix by the S/O/W technique to form composite microspheres. In vitro release study indicated that BSA was slowly released from the PLGA composite microspheres over 60 days with a reduced initial burst (11.42 ± 2.17% within 24 h). The potential mechanism of reduced initial burst and protein protection using this drug delivery system was analyzed through observing the degradation process of carriers and fitting drug release data with various kinetic models. The secondary structure of encapsulated BSA was well maintained through the steric barrier effect of ARM lecithin nanoparticles, which avoided exposure of proteins to the organic solvent during the preparation procedure. In addition, the PLGA composite microspheres exhibited superior biocompatibility without notable cytotoxicity. These results suggested that ARM lecithin nanoparticles/PLGA composite microspheres could be a promising platform for long-term protein delivery with a reduced initial burst.