Dyeing and antibacterial activation with methylene blue of a cyclodextrin modified polyester vascular graft

Bioinspired multifunctional injectable hydrogel for hemostasis and infected wound management

Routine wound management faces significant challenges including rebleeding and bacterial infection that affect millions of people each year. However, conventional wound dressings (e.g., gauze, bandage) are limited to simply cover the injured surfaces and rarely show special functionality to promote the wound recovery. Currently, injectable hydrogels have been widely designed as multifunctional wound dressings to manage the hemostatic and wound healing process. Nevertheless, the integration of multiple functions through simple composition and easy construction is still difficult and hardly achieved. Herein, we reported a bioinspired multifunctional injectable hydrogel (CQCS@gel) consisted of only two components, catechol-functionalized quaternized chitosan (CQCS) and dibenzaldehyde-terminated poly(ethylene glycol) (DB-PEG₂₀₀₀). The building blocks endowed CQCS@gel with tissue-adhesive, antibacterial, antioxidant, self-healing and pH-responsive properties. Based on the in vivo hemostatic study, quick hemostasis for acute tissue injuries such as liver and carotid wounds was realized owing to the rapid gelation rate and strong tissue-adhesiveness of CQCS@gel. Moreover, CQCS@gel remarkably boosted the chronic recovery process of MRSA-infected cutaneous wounds by promoting collagen deposition, hair follicles regeneration and angiogenesis. Overall, this multifunctional injectable hydrogel shows potentials as a universal wound dressing in clinical applications, enabling both hemostasis and infected wound management. STATEMENT OF SIGNIFICANCE: This is the first report showing the multifunctional injectable hydrogel (CQCS@gel) consisted of catechol-functionalized quaternized chitosan and dibenzaldehyde-terminated poly(ethylene glycol). The incorporation of quaternary ammonium groups imparted the CQCS@gel with outstanding contact-active bacterial killing efficiency and the catechol moieties enhanced its tissue adhesive and antioxidant properties. Moreover, the reversible imine crosslinks endowed the CQCS@gel with self-healing and pH-responsive drug release capabilities. These multiple functions were integrated into a single injectable hydrogel system with easy availability and low cost. In vitro and in vivo results showed that the newly designed hydrogel was biocompatible, realized successful sealing hemostasis under multiple bleeding scenarios and enabled accelerated healing of infected skin wounds.

Pre-clinical In Vitro Models of Vascular Graft Coating in the Prevention of Vascular Graft Infection: A Systematic Review

OBJECTIVE

Vascular graft infection (VGI) is a feared complication. Prevention is of the utmost importance and vascular graft coatings (VGCs) could offer a potential to do this, with in vitro research a first crucial step. The aim of this study was to summarise key features of in vitro models investigating coating strategies to prevent VGI in order to provide guidance for the setup of future translational research.

DATA SOURCES

A comprehensive search was performed in MEDLINE, Embase, and Web of Science.

METHODS

A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. For each database, a specific search strategy was developed. Quality was assessed with the Toxicological data Reliability Assessment Tool (ToxRTool). In vitro models using a VGC and inoculation of the graft with a pathogen were included. The type of graft, coating, and pathogen were summarised. The outcome assessment in each study was evaluated.

RESULTS

In total, 4 667 studies were identified, of which 45 papers met the inclusion criteria. The majority used polyester grafts (68.2%). Thirty-one studies (68.9%) included antibiotics, and nine studies (20%) used a commercial silver graft in their protocol. New antibacterial strategies (e.g., proteolytic enzymes) were investigated. A variety of testing methods was found and focused mainly on bacterial adherence, coating adherence and dilution, biofilm formation, and cytotoxicity. Ninety-three per cent of the studies (n = 41) were considered unreliable.

CONCLUSION

Polyester is the preferred type of graft to coat on. The majority of coating studies are based on antibiotics; however, new coating strategies (e.g., antibiofilm coating) are coming. Many in vitro setups are available. In vitro studies have great potential, they can limit the use, but cannot replace in vivo studies completely. This paper can be used as a guidance document for future in vitro research.

Cyclodextrins: Structural, Chemical, and Physical Properties, and Applications

Due to their unique structural, physical and chemical properties, cyclodextrins and their derivatives have been of great interest to scientists and researchers in both academia and industry for over a century. Many of the industrial applications of cyclodextrins have arisen from their ability to encapsulate, either partially or fully, other molecules, especially organic compounds. Cyclodextrins are non-toxic oligopolymers of glucose that help to increase the solubility of organic compounds with poor aqueous solubility, can mask odors from foul-smelling compounds, and have been widely studied in the area of drug delivery. In this review, we explore the structural and chemical properties of cyclodextrins that give rise to this encapsulation (i.e., the formation of inclusion complexes) ability. This review is unique from others written on this subject because it provides powerful insights into factors that affect cyclodextrin encapsulation. It also examines these insights in great detail. Later, we provide an overview of some industrial applications of cyclodextrins, while emphasizing the role of encapsulation in these applications. We strongly believe that cyclodextrins will continue to garner interest from scientists for many years to come, and that novel applications of cyclodextrins have yet to be discovered.

The Role of β-Cyclodextrin in the Textile Industry-Review

β-Cyclodextrin (β-CD) is an oligosaccharide composed of seven units of D-(+)-glucopyranose joined by α-1,4 bonds, which is obtained from starch. Its singular trunk conical shape organization, with a well-defined cavity, provides an adequate environment for several types of molecules to be included. Complexation changes the properties of the guest molecules and can increase their stability and bioavailability, protecting against degradation, and reducing their volatility. Thanks to its versatility, biocompatibility, and biodegradability, β-CD is widespread in many research and industrial applications. In this review, we summarize the role of β-CD and its derivatives in the textile industry. First, we present some general physicochemical characteristics, followed by its application in the areas of dyeing, finishing, and wastewater treatment. The review covers the role of β-CD as an auxiliary agent in dyeing, and as a matrix for dye adsorption until chemical modifications are applied as a finishing agent. Finally, new perspectives about its use in textiles, such as in smart materials for microbial control, are presented.

Cyclodextrin-modified poly(octamethylene citrate) polymers towards enhanced sorption properties

Herein, we describe the synthesis of poly(1,8-octamethylene citrate) materials modified in the bulk with 2-hydroxypropyl-β-cyclodextrin (cPOCCD), biodegradable elastomers with intrinsic sorption properties for drug delivery. The chemical structure, physicochemical properties, in vitro drug loading and release profiles of cPOCCD were investigated. Thus, cPOCCD polyesters absorb the studied drugs more effective and release them for a longer period of time than poly(1,8-octamethylene citrate) materials not containing cyclodextrins.

Cyclodextrin modified PLLA parietal reinforcement implant with prolonged antibacterial activity

The use of textile meshes in hernia repair is widespread in visceral surgery. Though, mesh infection is a complication that may prolong the patient recovery period and consequently presents an impact on public health economy. Such concern can be avoided thanks to a local and extended antibiotic release on the operative site. In recent developments, poly-l-lactic acid (PLLA) has been used in complement of polyethyleneterephthalate (Dacron®) (PET) or polypropylene (PP) yarns in the manufacture of semi-resorbable parietal implants. The goal of the present study consisted in assigning drug reservoir properties and prolonged antibacterial effect to a 100% PLLA knit through its functionalization with a cyclodextrin polymer (polyCD) and activation with ciprofloxacin. The study focused i) on the control of degree of polyCD functionalization of the PLLA support and on its physical and biological characterization by Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC) and cell viability, ii) on the understanding of drug/meshes interaction using mathematic model and iii) on the correlation between drug release studies in phosphate buffer saline (PBS) and microbiological evaluation of meshes and release medium against E. coli and S. aureus. All above mentioned tests highlighted the contribution of polyCD on the improved performances of the resulting antibacterial implantable material.

STATEMENT OF SIGNIFICANCE

1. We managed for the first time, with well-defined parameters in terms of temperature and time of treatment, to functionalize a bio-absorbable synthetic material to improve drug sorption and drug release properties without affecting its mechanical properties. 2. We analyzed for the first time the degradation of our coating products by mass spectroscopy to show that only citrate and cyclodextrin residues (and glucose units) without any cytotoxicity are formed. 3. We managed to improve the mechanical properties of the PLA with the cyclodextrin polymer to form a composite. The assembly (cyclodextrin polymer and PLLA) remains biodegradable.

Synthesis of β-Cyclodextrin-Based Electrospun Nanofiber Membranes for Highly Efficient Adsorption and Separation of Methylene Blue

Water-insoluble β-cyclodextrin-based fibers were synthesized by electrospinining followed by thermal cross-linking. The fibers were characterized by field-emission scanning electron microscopic (FE-SEM) and Fourier transformed infrared spectrometer (FT-IR). The highly insoluble fraction obtained from different pH values (3-11) indicates successful cross-linking reactions and their usability in aqueous solution. After the cross-linking reaction, the fibers' tensile strength increases significantly and the BET surface area is 19.49 m(2)/g. The cross-linked fibers exhibited high adsorption capacity for cationic dye methylene blue (MB) with good recyclability. The adsorption performance can be fitted well with pseudo-second-order model and Langmuir isotherm model. The maximum adsorption capacity is 826.45 mg/g according to Langmuir fitting. Due to electrostatic repulsion, the fibers show weak adsorption toward negatively charged anionic dye methyl orange (MO). On the basis of the selective adsorption, the fiber membrane can separate the MB/MO mixture solution by dynamic filtration at a high flow rate of 150 mL/min. The fibers can maintain good fibrous morphology and high separation efficiency even after five filtration-regeneration cycles. The obtained results suggested potential applications of β-cyclodextrin-based electrospun fibers in the dye wastewater treatment field.

Evaluation of sorption capacity of antibiotics and antibacterial properties of a cyclodextrin-polymer functionalized hydroxyapatite-coated titanium hip prosthesis

Infection still present as one of common complications after total hip replacement (∼2.5%), which may cause serious outcomes. For preventing such risk, loading antibiotics onto implants for increasing local drug concentration at targeted sites could be a solution. This study aims at modifying the surface of hydroxyapatite (HA) coated titanium hip implant material (Ti-HA) with polymer of cyclodextrin (polyCD) for loading antibiotics, to achieve a sustained local drug delivery. Two widely applied antibiotics (tobramycin and rifampicin) in orthopedic surgery were loaded alone or in combination. The drug adsorption isotherm, drug release kinetics and drug's efficacy were thoroughly investigated. The results proved that polyCD coating significantly improved the affinity of both drugs to Ti-HA surface, while the mechanism of drug-polyCD interaction varies from the nature of drug, courtesy of the structural complex of polyCD. The advantage of dual-drug loading was highlighted by its strong efficacy against both Staphylococcus aureus and Enterobacter cloacae, which overcomes the limitation of mono-drug loading for an effective treatment against both bacterial strains. The prolonged antibacterial activity of antibiotic loaded Ti-HA-polyCD samples confirmed that polyCD could be a promising drug-delivery system, for sustained antibiotics release or other potential applications e.g., antimitotic agent release.