Development of poly(vinyl alcohol) porous scaffold with high strength and well ciprofloxacin release efficiency

Chitosan nanofibrous scaffold with graded and controlled release of ciprofloxacin and BMP-2 nanoparticles for the conception of bone regeneration

The repair of bone defects using grafts is commonly employed in clinical practice. However, the risk of infection poses a significant concern. Tissue engineering scaffolds with antibacterial functionalities offer a better approach for bone tissue repair. In this work, firstly, two kinds of nanoparticles were prepared using chitosan to complex with ciprofloxacin and BMP-2, respectively. The ciprofloxacin complex nanoparticles improved the dissolution efficiency of ciprofloxacin achieving a potent antibacterial effect and cumulative release reached 95 % in 7 h. For BMP-2 complexed nanoparticles, the release time points can be programmed at 80 h, 100 h or 180 h by regulating the number of coating chitosan layers. Secondly, a functional scaffold was prepared by combining the two nanoparticles with chitosan nanofibers. The microscopic nanofiber structure of the scaffold with 27.28 m2/g specific surface area promotes cell adhesion, high porosity provides space for cell growth, and facilitates drug loading and release. The multifunctional scaffold exhibits programmed release function, and has obvious antibacterial effect at the initial stage of implantation, and releases BMP-2 to promote osteogenic differentiation of mesenchymal stem cells after the antibacterial effect ends. The scaffold is expected to be applied in clinical bone repair and graft infection prevention.

Applications of propolis-based materials in wound healing

Due to its excellent antiseptic efficacy and antimicrobial properties, propolis has shown attractive advantages in wound dressings. However, an inclusive review of the propolis-based materials as a wound dressing is still lacking. The current short review summarizes the skin wound healing process, relates evaluation parameters, and then reviews the refined propolis-based materials dressings such as antimicrobial property, adhesion and hemostasis, anti-inflammatory and substance delivery. The approaches implemented to achieve these functions are classified and discussed. Furthermore, applications of propolis wound dressing for treating different types of wounds such as heal wounds, burns, and ulcers are presented. The future directions of propolis-based wound dressings for wound healing are further proposed. This review showed that propolis-based materials might be a promising new dressing for wound occlusion and tissue repairing.

Efficient green silver nanoparticles-antibiotic combinations against antibiotic-resistant bacteria

Antibiotic-resistant bacterial strains and the consequent surge in infections caused by them have become major public health concerns. Silver nanoparticles (AgNPs) exhibit antibacterial properties and have wide applications in biomedical sciences. In this study, AgNPs were synthesized in the presence of antibiotics: Ceftazidime (Cft), Cefotaxime (Cef), Ceftriaxone (Cfx), and Cefepime (Cpm), along with the extract of Mentha longifolia. Mentha longifolia-based AgNPs were kept as the control for all experiments. The associated metabolites, structural properties, surface charges, and antibacterial activity of the AgNPs were also evaluated. Overall, a blue-shift of SPR peaks was observed for control AgNPs (λmax = 421 nm, 422 nm, 426 nm, and 406 nm for Cft-AgNPs, Cef-AgNPs, Cfx-AgNPs, and Cpm-AgNPs, respectively), compared to the control (λmax = 438 nm). Fourier-transform infrared spectroscopy showed that antibiotic-based AgNPs had distinct peaks that corresponded to the respective antibiotics, which were not observed in the control. XRD analysis showed that there were observed changes in crystallinity in antibiotic-based AgNPs compared to the control. TEM images revealed that all samples had spherical nanoparticles with different sizes and distributions compared to the control. The Zeta potential for extract-based AgNPs was - 33.6 mV, compared to -19.6 mV for Cft-AgNPs, -2 mV for Cef-AgNPs, -21.1 mV for Cfx-AgNPs, and - 24.2 mV for Cpm-AgNPs. The increase in the PDI value for antibiotic-based AgNPs also showed a highly polydisperse distribution. However, the antibiotic-AgNPs conjugates showed significantly higher activity against pathogenic bacteria. The addition of antibiotics to AgNPs brought significant changes in structural properties and antibacterial activities.

Polymer based dual drug delivery system for targeted treatment of fluoroquinolone resistant Staphylococcus aureus mediated infections

The present study attempts to treat S. aureus-induced soft skin infections using a combinatorial therapy with an antibiotic, Ciprofloxacin (CIP), and an efflux pump inhibitor 5-Nitro-2-(3-phenylpropoxy) pyridine (5-NPPP) through a smart hydrogel delivery system. The study aims to reduce the increasing rates of infections and antimicrobial resistance; therefore, an efflux pump inhibitor molecule is synthesized and delivered along with an antibiotic to re-sensitize the pathogen towards antibiotics and treat the infections. CIP-loaded polyvinyl alcohol (PVA) hydrogels at varying concentrations were fabricated and optimized by a chemical cross-linking process, which exhibited sustained drug release for 5 days. The compound 5-NPPP loaded hydrogels provided linear drug release for 2 days, necessitating the need for the development of polymeric nanoparticles to alter the release drug pattern. 5-NPPP loaded Eudragit RSPO nanoparticles were prepared by modified nanoprecipitation-solvent evaporation method, which showed optimum average particle size of 230-280 nm with > 90% drug entrapment efficiency. The 5-NPPP polymeric nanoparticles loaded PVA hydrogels were fabricated to provide a predetermined sustained release of the compound to provide a synergistic effect. The selected 7% PVA hydrogels loaded with the dual drugs were evaluated using Balb/c mice models induced with S. aureus soft skin infections. The results of in vivo studies were evidence that the dual drugs loaded hydrogels were non-toxic and reduced the bacterial load causing re-sensitization towards antibiotics, which could initiate re-epithelization. The research concluded that the PVA hydrogels loaded with CIP and 5-NPPP nanoparticles could be an ideal and promising drug delivery system for treating S. aureus-induced skin infections.

Ciprofloxacin-Loaded Silver Nanoparticles as Potent Nano-Antibiotics against Resistant Pathogenic Bacteria

Silver nanoparticles (AgNPs) have demonstrated numerous physicochemical, biological, and functional properties suitable for biomedical applications, including antibacterial and drug carrier properties. In the present study, the antibiotic, ciprofloxacin (CIP), was loaded onto AgNPs, which were synthesized via the chemical reduction method, thereby enhancing CIP's antibacterial activity against Gram-negative (Acinetobacter baumannii and Serratia marcescens) and Gram-positive (Staphylococcus aureus) bacterial strains. Polyethylene glycol-400 (PEG) was used to prepare an AgNPs-PEG conjugate with enhanced stability and to act as the linker between CIP and AgNPs, to produce the novel nanocomposite, AgNPs-PEG-CIP. The prepared AgNPs and their conjugates were characterized by ultraviolet-visible spectrophotometry, Fourier-transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy with energy-dispersive X-ray spectroscopy, transmission electron microscopy, zeta potential analysis, and dynamic light scattering techniques. The inhibitory activity of AgNPs and their conjugates on the growths of pathogenic bacteria was assessed using the well-diffusion method. The results showed the enhanced antibacterial effects of AgNPs-CIP compared to CIP alone. The AgNPs-PEG-CIP nanocomposite showed excellent inhibitory effects against bacterial isolates, with its inhibition zones diameters reaching 39, 36, and 40 mm in S. aureus, A. baumannii, and S. marcescens, respectively. The minimum inhibitory concentration and minimum bactericidal concentration of fogNPs and their conjugates and their antibiofilm effects were also determined. The antioxidant potentials of AgNPs and their conjugates, tested via their 1,1-diphenyl-2-picryl-hydrazyl (DPPH) scavenging ability, showed that the activity increased with increasing AgNPs concentration and the addition of the PEG and/or CIP. Overall, according to the results obtained in the present study, the new nanocomposite, AgNPs-PEG-CIP, showed the highest antibacterial, antibiofilm, and antioxidant activity against the pathogenic bacteria tested, compared to CIP alone. The preparation has high clinical potential for prospective use as an antibacterial agent.

Progress in Antibacterial Hydrogel Dressing

Antibacterial hydrogel has excellent antibacterial property and good biocompatibility, water absorption and water retention, swelling, high oxygen permeability, etc.; therefore, it widely applied in biomedicine, intelligent textiles, cosmetics, and other fields, especially for medical dressing. As a wound dressing, the antibacterial hydrogel has the characteristics of absorbing wound liquid, controlling drug release, being non-toxic, being without side effects, and not causing secondary injury to the wound. Its preparation method is simple, and can crosslink via covalent or non-covalent bond, such as γ-radiation croFsslinking, free radical polymerization, graft copolymerization, etc. The raw materials are easy to obtain; usually these include chondroitin sulfate, sodium alginate, polyvinyl alcohol, etc., with different raw materials being used for different antibacterial modes. According to the hydrogel matrix and antibacterial mode, the preparation method, performance, antibacterial mechanism, and classification of antibacterial hydrogels are summarized in this paper, and the future development direction of the antibacterial hydrogel as wound dressing is proposed.

Fabrication and Characterization of Gelatin/Polyvinyl Alcohol Composite Scaffold

In this study, porous scaffold materials based on polyvinyl alcohol (PVA) and gelatin (Gel) were successfully fabricated and characterized. The mechanism of the reaction, morphology, and crystallinity were investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). In addition, thermogravimetric analysis (TGA) was performed together with differential scanning calorimetry (DSC) for examining the thermostability and phase transformation of the scaffolds. Degradation and swelling studies of PVA/Gel composite scaffold materials were performed in phosphate-buffered saline. Finally, the mechanical performances had been determined. According to the results, the polymer matrix that was formed by the combination of PVA and gelatin had better thermal stability. The synthesized composite scaffold was amorphous in nature. The addition of gelatin did not affect the fishbone-like microstructure of PVA, which ensures the excellent mechanical properties of the PVA scaffold. The denaturation temperature and elastic modulus of the PVA scaffold were improved by the gelatin addition, but the physical and chemical properties of the PVA scaffold were weakened when the gelatin content exceeded 10%. In addition, the PVA-10G sample has suitable degradability. Therefore, the PVA/Gel composite scaffold might potentially be applied in the field of tissue engineering that demands high strength.

Bio-derived and biocompatible poly(lactic acid)/silk sericin nanogels and their incorporation within poly(lactide-co-glycolide) electrospun nanofibers

Bio-derived and biocompatible nanogels based on poly(lactic acid) (PLA) and silk sericin (SS) have been synthesized for the first time.

Enhancement of hydrophilicity, biocompatibility and biodegradability of poly(ε-caprolactone) electrospun nanofiber scaffolds using poly(ethylene glycol) and poly(L-lactide-co-ε-caprolactone-co-glycolide) as additives for soft tissue engineering

In this study, poly(ε-caprolactone) (PCL) has been blended with a more hydrophilic poly(ethylene glycol) (PEG) and with a biocompatible block-co-polymer: poly(L-lactide-co-ε-caprolactone-co-glycolide) (PLCG) in order to improve hydrophilicity, biocompatibility and biodegradability of PCL. PCL and the blend solutions were subjected to electrospinning to produce nanofiber scaffolds by the addition of only 1 wt% of PEG and PLCG either singly or in combination in PCL to retain the mechanical properties of the scaffolds. PCL-PEG-PLCG ternary and two binary (PCL-PEG and PCL-PLCG) blend nanofiber scaffolds have been prepared for comparison. The resulting nanofibers showed a smooth and flaw-free surface and the diameter of the nanofibers displayed a normal distribution. The PCL-PEG nanofiber scaffold showed improved hydrophilicity [water contact angle (WCA) ∼84°] over pristine PCL (WCA ∼127°); while PCL-PLCG and PCL-PEG-PLCG scaffolds exhibited absolute wetting by water, likely due to high porosity. In vitro biocompatibility studies using gingival mesenchymal stem cells (gMSCs) suggested that, both the PCL and the blend scaffolds were biocompatible supporting cell-viability and growth of gMSCs following their seeding on these scaffolds. Biodegradation studies in phosphate buffer solution showed that the addition of PEG and PLCG in PCL increased the weight loss of scaffolds with time, indicating higher extent of biodegradation in the blend scaffolds and the weight loss followed the power law curve with time.

Morphology, Thermal and Mechanical Properties of Co-Continuous Porous Structure of PLA/PVA Blends by Phase Separation

Poly (lactic acid) (PLA) was blended with poly (vinyl alcohol) (PVA) in the composition of 70/30 (L7V3), 60/40 (L6V4), and 50/50 (L5V5) wt.%. L7V3 exhibits a sea-island morphology, while L6V4 and L5V5 show co-continuous phase morphologies. These polymers exhibited a solitary glass transition temperature, which obeyed the Fox equation. Thereafter, the blends were made porous by an etching process in hot water (35 °C) for 0-7 days, to remove PVA. The maximum etched PVA content of L7V3, L6V4, and L5V5 was 0.5%, 13.4%, and 36.1%, respectively; hence, L5V5 exhibited a co-continuous porous morphology with the porosity of 43.4%, the degree of swelling of 47.5%, and the pore size of 2 µm. The degree of crystallinity of PLA, exposed PLA, and L7V3 showed an insignificant change. L5V5, having the highest porosity, demonstrated the highest increase in the degree of crystallinity of approximately two times, because water induced the crystallization of PLA. The high porosity of L5V5 exhibited an excellent absorption property by increasing absorption energy more than two times, as obtained by micro indention. It had the maximum indentation depth more than 250 µm. Flexural and tensile properties considerably decreased with an increase in the porosity.

A novel magnetic bifunctional nanocomposite scaffold for photothermal therapy and tissue engineering

In recent years, porous bifunctional scaffolds with hyperthermal and tissue regeneration functions play an essential role in the efficient cancerous bone tumors treatment. In this work, the nanocomposite scaffolds of gelatin (polymer phase) and akermanite (ceramic phase) were prepared by entrapping carboxyl-functionalized multi-walled carbon nanotube (MWNT) and embedding magnetic nanoparticles of iron oxide into the porous matrix as photothermal conversion agents. The obtained scaffolds and their components were characterized using FTIR, FESEM, TEM, EDS, DLS, and VSM analysis. The mechanical properties of the prepared scaffolds were also investigated. The swelling behavior of the scaffolds in PBS as well as biodegradation and protein adsorption capability were evaluated. The addition of nanoparticles into the gelatin/akermanite matrix efficiently increased the adsorption of bovine serum albumin on the surface of the composite scaffold and contrarily decreased its degradation rate in the presence of lysozyme. The prepared scaffolds exhibited a high photothermal performance using NIR laser with different power intensity and irradiation time. Finally, the biocompatibility of the scaffold was confirmed using G292 osteoblastic cells through MTT assays. It can therefore be concluded that synthesized scaffolds have a great potential in bone tissue engineering and probably treatment of tumor related bone defects.

Fabrication Strategies of Scaffolds for Delivering Active Ingredients for Tissue Engineering

Designing scaffolds with optimum properties is an essential factor for tissue engineering success. They can be seeded with isolated cells or loaded with drugs to stimulate the body ability to repair or regenerate the injured tissues by acting as centers for new tissue formation. Recently, scaffolds gained a significant interest as principal candidates for tissue engineering due to overcoming the autograft or allograft's associated problems. The advancement of the tissue engineering field relies mainly on the introduction of new biomaterials for scaffolds' fabrication. This review presents and criticizes different scaffolds' fabrication techniques with particular emphasis on the fibrous, injectable in situ forming, foam, 3D freeze-dried, 3D printed, and 4D scaffolds. This article highlights on scaffolds' composition which would be beneficial for developing scaffolds that could potentially help to meet the demand for both drug delivery and tissue regeneration.

Antimicrobial hydrogels: promising materials for medical application

The rapid emergence of antibiotic resistance in pathogenic microbes is becoming an imminent global public health problem. Local application of antibiotics might be a solution. In local application, materials need to act as the drug delivery system. The drug delivery system should be biodegradable and prolonged antibacterial effect should be provided to satisfy clinical demand. Hydrogel is a promising material for local antibacterial application. Hydrogel refers to a kind of biomaterial synthesized by a water-soluble natural polymer or a synthesized polymer, which turns into gel according to the change in different signals such as temperature, ionic strength, pH, ultraviolet exposure etc. Because of its high hydrophilicity, unique three-dimensional network, fine biocompatibility and cell adhesion, hydrogel is one of the suitable biomaterials for drug delivery in antimicrobial areas. In this review, studies from the past 5 years were reviewed, and several types of antimicrobial hydrogels according to different ingredients, different preparations, different antimicrobial mechanisms, different antimicrobial agents they contained and different applications, were summarized. The hydrogels loaded with metal nanoparticles as a potential method to solve antibiotic resistance were highlighted. Finally, future prospects of development and application of antimicrobial hydrogels are suggested.

Biocompatible nanocomposite scaffolds based on copolymer-grafted chitosan for bone tissue engineering with drug delivery capability

Significant efforts have been made to develop a suitable biocompatible scaffold for bone tissue engineering. In this work, a chitosan-graft-poly(acrylic acid-co-acrylamide)/hydroxyapatite nanocomposite scaffold was synthesized through a novel multi-step route. The prepared scaffolds were characterized for crystallinity, morphology, elemental analysis, chemical bonds, and pores size in their structure. The mechanical properties (i.e. compressive strength and elastic modulus) of the scaffolds were examined. Further, the biocompatibility of scaffolds was determined by MTT assays on HUGU cells. The result of cell culture experiments demonstrated that the prepared scaffolds have good cytocompatibility without any cytotoxicity, and with the incorporation of hydroxyapatite in their structure improves cell viability and proliferation. Finally, celecoxib as a model drug was efficiently loaded into the prepared scaffolds because of the large specific surface area. The in vitro release of the drug displayed a biphasic pattern with a low initial burst and a sustained release of up to 14days. Furthermore, different release kinetic models were employed for the description of the release process. The results suggested that the prepared cytocompatible and non-toxic nanocomposite scaffolds might be efficient implants and drug carriers in bone-tissue engineering.

Polyethylene glycol as a promising synthetic material for repair of spinal cord injury

Polyethylene glycol is a synthetic, biodegradable, and water-soluble polyether. Owing to its good biological and material properties, polyethylene glycol shows promise in spinal cord tissue engineering applications. Although studies have examined repairing spinal cord injury with polyethylene glycol, these compelling findings have not been recently reviewed or evaluated as a whole. Thus, we herein review and summarize the findings of studies conducted both within and beyond China that have examined the repair of spinal cord injury using polyethylene glycol. The following summarizes the results of studies using polyethylene glycol alone as well as coupled with polymers or hydrogels: (1) polyethylene glycol as an adjustable biomolecule carrier resists nerve fiber degeneration, reduces the inflammatory response, inhibits vacuole and scar formation, and protects nerve membranes in the acute stage of spinal cord injury. (2) Polyethylene glycol-coupled polymers not only promote angiogenesis but also carry drugs or bioactive molecules to the injury site. Because such polymers cross both the blood-spinal cord and blood-brain barriers, they have been widely used as drug carriers. (3) Polyethylene glycol hydrogels have been used as supporting substrates for the growth of stem cells after injury, inducing cell migration, proliferation, and differentiation. Simultaneously, polyethylene glycol hydrogels isolate or reduce local glial scar invasion, promote and guide axonal regeneration, cross the transplanted area, and re-establish synaptic connections with target tissue, thereby promoting spinal cord repair. On the basis of the reviewed studies, we conclude that polyethylene glycol is a promising synthetic material for use in the repair of spinal cord injury.