Cyclodextrin and maltodextrin finishing of a polypropylene abdominal wall implant for the prolonged delivery of ciprofloxacin

Coatings of Cyclodextrin/Citric-Acid Biopolymer as Drug Delivery Systems: A Review

In the early 2000s, a method for cross-linking cyclodextrins (CDs) with citric acid (CTR) was developed. This method was nontoxic, environmentally friendly, and inexpensive compared to the others previously proposed in the literature. Since then, the CD/CTR biopolymers have been widely used as a coating on implants and other materials for biomedical applications. The present review aims to cover the chemical properties of CDs, the synthesis routes of CD/CTR, and their applications as drug-delivery systems when coated on different substrates. Likewise, the molecules released and other pharmaceutical aspects involved are addressed. Moreover, the different methods of pretreatment applied on the substrates before the in situ polymerization of CD/CTR are also reviewed as a key element in the final functionality. This process is not trivial because it depends on the surface chemistry, geometry, and physical properties of the material to be coated. The biocompatibility of the polymer was also highlighted. Finally, the mechanisms of release generated in the CD/CTR coatings were analyzed, including the mathematical model of Korsmeyer-Peppas, which has been dominantly used to explain the release kinetics of drug-delivery systems based on these biopolymers. The flexibility of CD/CTR to host a wide variety of drugs, of the in situ polymerization to integrate with diverse implantable materials, and the controllable release kinetics provide a set of advantages, thereby ensuring a wide range of future uses.

Citric Acid: A Multifunctional Pharmaceutical Excipient

Citric acid, a tricarboxylic acid, has found wide application in the chemical and pharmaceutical industry due to its biocompatibility, versatility, and green, environmentally friendly chemistry. This review emphasizes the pharmaceutical uses of citric acid as a strategic ingredient in drug formulation while focusing on the impact of its physicochemical properties. The functionality of citric acid is due to its three carboxylic groups and one hydroxyl group. These allow it to be used in many ways, including its ability to be used as a crosslinker to form biodegradable polymers and as a co-former in co-amorphous and co-crystal applications. This paper also analyzes the effect of citric acid in physiological processes and how this effect can be used to enhance the attributes of pharmaceutical preparations, as well as providing a critical discussion on the issues that may arise out of the presence of citric acid in formulations.

Nutraceutical Concepts and Dextrin-Based Delivery Systems

Nutraceuticals are bioactive or chemical compounds acclaimed for their valuable biological activities and health-promoting effects. The global community is faced with many health concerns such as cancers, cardiovascular and neurodegenerative diseases, diabetes, arthritis, osteoporosis, etc. The effect of nutraceuticals is similar to pharmaceuticals, even though the term nutraceutical has no regulatory definition. The usage of nutraceuticals, to prevent and treat the aforementioned diseases, is limited by several features such as poor water solubility, low bioavailability, low stability, low permeability, low efficacy, etc. These downsides can be overcome by the application of the field of nanotechnology manipulating the properties and structures of materials at the nanometer scale. In this review, the linear and cyclic dextrin, formed during the enzymatic degradation of starch, are highlighted as highly promising nanomaterials- based drug delivery systems. The modified cyclic dextrin, cyclodextrin (CD)-based nanosponges (NSs), are well-known delivery systems of several nutraceuticals such as quercetin, curcumin, resveratrol, thyme essential oil, melatonin, and appear as a more advanced drug delivery system than modified linear dextrin. CD-based NSs prolong and control the nutraceuticals release, and display higher biocompatibility, stability, and solubility of poorly water-soluble nutraceuticals than the CD-inclusion complexes, or uncomplexed nutraceuticals. In addition, the well-explored CD-based NSs pathways, as drug delivery systems, are described. Although important progress is made in drug delivery, all the findings will serve as a source for the use of CD-based nanosystems for nutraceutical delivery. To sum up, our review introduces the extensive literature about the nutraceutical concepts, synthesis, characterization, and applications of the CD-based nano delivery systems that will further contribute to the nutraceutical delivery with more potent nanosystems based on linear dextrins.

Antimicrobial Meshes for Hernia Repair: Current Progress and Perspectives

Recent advances in the development of biomaterials have given rise to new options for surgery. New-generation medical devices can control chemical breakdown and resorption, prevent post-operative adhesion, and stimulate tissue regeneration. For the fabrication of medical devices, numerous biomaterials can be employed, including non-degradable biomaterials (silicone, polypropylene, expanded polytetrafluoroethylene) or biodegradable polymers, including implants and three-dimensional scaffolds for tissue engineering, which require particular physicochemical and biological properties. Based on the combination of new generation technologies and cell-based therapies, the biocompatible and bioactive properties of some of these medical products can lead to progress in the repair of injured or harmed tissue and in tissue regeneration. An important aspect in the use of these prosthetic devices is the associated infection risk, due to the medical complications and socio-economic impact. This paper provides the latest achievements in the field of antimicrobial surgical meshes for hernia repair and discusses the perspectives in the development of these innovative biomaterials.

Latest Trends on the Attenuation of Systemic Foreign Body Response and Infectious Complications of Synthetic Hernia Meshes

Throughout the past few years, hernia incidence has remained at a high level worldwide, with more than 20 million people requiring hernia surgery each year. Synthetic hernia meshes play an important role, providing a microenvironment that attracts and harbors host cells and acting as a permanent roadmap for intact abdominal wall reconstruction. Nevertheless, it is still inevitable to cause not-so-trivial complications, especially chronic pain and adhesion. In long-term studies, it was found that the complications are mainly caused by excessive fibrosis from the foreign body reaction (FBR) and infection resulting from bacterial colonization. For a thorough understanding of their complex mechanism and providing a richer background for mesh development, herein, we discuss different clinical mesh products and explore the interactions between their structure and complications. We further explored progress in reducing mesh complications to provide varied strategies that are informative and instructive for mesh modification in different research directions. We hope that this work will spur hernia mesh designers to step up their efforts to develop more practical and accessible meshes by improving the physical structure and chemical properties of meshes to combat the increasing risk of adhesions, infections, and inflammatory reactions. We conclude that further work is needed to solve this pressing problem, especially in the analysis and functionalization of mesh materials, provided of course that the initial performance of the mesh is guaranteed.

A Phase Inversion-Based Microfluidic Fabrication of Helical Microfibers towards Versatile Artificial Abdominal Skin

Microfluidic spinning technology (MST), incorporating microfluidics with chemical reactions, has gained considerable interest for constructing anisotropic advanced microfibers, especially helical microfibers. However, these efforts suffer from the limited material choices, restricting their applications. Here, a new phase inversion-based microfluidic spinning (PIMS) method is proposed for producing helical microfibers. This method undergoes a physicochemical phase inversion process, which is capable of efficiently manufacturing strong (tensile stress of more than 25 MPa), stretchable, flexible and biocompatible helical microfibers. The helical microfibers can be used to fabricate bi-oriented stretchable artificial abdominal skin, preventing incisional hernia formation and promoting the wound healing without conglutination. This research not only offers a universal approach to design helical microfibers but also provides a new insight into artificial skin.

MOF-based multi-stimuli-responsive supramolecular nanoplatform equipped with macrocycle nanovalves for plant growth regulation

Controllable and on-demand delivery of agrochemicals such as plant hormones is conducive to improving agrochemicals utilization, tackling water and environmental pollution, reducing soil acidification, and realizing the goals of precision agriculture. Herein, a smart plant hormone delivery system based on metal-organic frameworks (MOFs) and supramolecular nanovalves, namely gibberellin (GA)-loaded CLT6@PCN-Q, is constructed through supramolecular host-guest interaction to regulate the growth of dicotyledonous Chinese cabbage and monocotyledonous wheat. The porous nanoscale MOF (NMOF) with a uniform diameter of 97 nm modified by quaternary ammonium (Q) stalks is served as a cargo reservoir, followed by the decoration of carboxylated leaning tower[6]arene (CLT6) based nanovalves on NMOF surfaces through host-guest interactions to fabricate CLT6@PCN-Q with a diameter of ∼101 nm and a zeta potential value of -13.2 mV. Interestingly, the as-fabricated supramolecular nanoplatform exhibits efficient cargo loading and multi-stimuli-responsive release under various external stimuli including pH, temperature, and competitive agent spermine (SPM), which can realize the on-demand release of cargo. In addition, GA-loaded CLT6@PCN-Q is capable of effectively promoting the seeds germination of wheat and stem growth of dicotyledonous Chinese cabbage and monocotyledonous wheat (1.86 and 1.30 times of control groups, respectively). The smart supramolecular nanoplatform based on MOFs and supramolecular nanovalves paves a way for the controlled delivery of plant hormones and other agrochemicals for promoting plant growth, offering new insights and methods to realize precision agriculture. STATEMENT OF SIGNIFICANCE: To achieve controllable and sustainable release of cargos such as agrochemicals, a smart MOF-based multi-stimuli-responsive supramolecular nanoplatform equipped with supramolecular nanovalves was fabricated via the host-guest interaction between quaternary ammonium stalks-functionalized nanoMOFs and water-soluble leaning tower[6]arene. The as-prepared supramolecular nanoplatform with uniform diameter distribution demonstrated good cargo release in response to various external stimuli. The installation of synthetic macrocycles could effectively reduce cargo loss in the pre-treatment process. This type of supramolecular nanoplatform exhibited good promoting effect on seed germination and plant growth dicotyledonous Chinese cabbage and monocotyledonous wheat. As an eco-friendly, controlled, and efficient cargo delivery system, this supramolecular nanoplatform will be a promising candidate in precision agriculture and controlled drug release to attract the broad readership.

History of cyclodextrin-based polymers in food and pharmacy: a review

Cyclodextrins are glucose macrocycles whose inclusional capabilities towards non-polar solutes can be modulated with the help of other macrostructures. The incorporation of cyclodextrin moieties into larger structures produces five types of new materials: crosslinked networks, functionalized chains, amphiphilic cyclodextrins, polyrotaxanes and nanocomposites. This review presents crosslinking and grafting to prepare covalently-attached cyclodextrins, and applications in the food and pharmaceutical sectors, from an historical point of view. In food science, applications include debittering of juices, retention of aromas and release of preservatives from packaging. In biomedical science, cyclodextrin polymers are applied classically to drug release, and more recently to gene delivery and regenerative medicine. The remarkable points are: 1) epichlorohydrin and diisocyanates have been extensively used as crosslinkers since the 1960s, but during the last two decades more complex cyclodextrin polymeric structures have been designed. 2) The evolution of cyclodextrin polymers matches that of macromolecular materials with regard to complexity, functionality and capabilities. 3) The use of cyclodextrin polymers as sorbents in the food sector came first, but smart packaging is now an active challenge. Cyclodextrins have also been recently used to design treatments against the coronavirus disease 2019 (COVID-19).

Functionalized Strategies and Mechanisms of the Emerging Mesh for Abdominal Wall Repair and Regeneration

Meshes have been the overwhelmingly popular choice for the repair of abdominal wall defects to retrieve the bodily integrity of musculofascial layer. Broadly, they are classified into synthetic, biological and composite mesh based on their mechanical and biocompatible features. With the development of anatomical repair techniques and the increasing requirements of constructive remodeling, however, none of these options satisfactorily manages the conditional repair. In both preclinical and clinical studies, materials/agents equipped with distinct functions have been characterized and applied to improve mesh-aided repair, with the importance of mesh functionalization being highlighted. However, limited information exists on systemic comparisons of the underlying mechanisms with respect to functionalized strategies, which are fundamental throughout repair and regeneration. Herein, we address this topic and summarize the current literature by subdividing common functions of the mesh into biomechanics-matched, macrophage-mediated, integration-enhanced, anti-infective and antiadhesive characteristics for a comprehensive overview. In particular, we elaborate their effects separately with respect to host response and integration and discuss their respective advances, challenges and future directions toward a clinical alternative. From the vastly different approaches, we provide insight into the mechanisms involved and offer suggestions for personalized modifications of these emerging meshes.

Fabrication and Characterization of Composite Meshes Loaded with Antimicrobial Peptides

Biomaterials-centered infection or implant-associated infection plays critical roles in all areas of medicine with implantable devices. The widespread over use of antibiotics has caused severe bacterial resistance and even super bugs. Therefore, the development of anti-infection implantable devices with non-antibiotic-based new antimicrobial agents is indeed a priority for all of us. In this study, antimicrobial composite meshes were fabricated with broad-spectrum antimicrobial peptides (AMPs). Macroporous polypropylene meshes with poly-caprolactone electrospun nanosheets were utilized as a substrate to load AMPs and gellan gum presented as a media to gel with AMPs. Different amounts of AMPs were loaded onto gellan gum to determine the appropriate dose. The surface morphologies, Fourier-transform infrared spectroscopy spectra, in vitro release profiles, mechanical performances, in vitro antimicrobial properties, and cytocompatibility of composite scaffolds were evaluated. Results showed that AMPs were loaded into the meshes successfully, the in vitro release of AMPs in phosphate-buffered saline was prolonged, and less than 60% peptides were released in 10 days. The mechanical properties of composite meshes were also within the scope of several commercial surgical meshes. Composite meshes with the AMP loading amount of over 3 mg/cm² showed inhibition against both Gram-negative and Gram-positive bacteria effectively, while they presented no toxicity to mammalian cells even at a loading amount of 10 mg/cm². These results demonstrate a new simple and practicable method to offer antimicrobial properties to medical devices for hernia repair.

Chitosan Cross-Linked Bio-based Antimicrobial Polypropylene Meshes for Hernia Repair Loaded with Levofloxacin HCl via Cold Oxygen Plasma

Polypropylene (PP) large pore size nets have been most widely used implants for hernia repair. Nevertheless, the growth of bacteria within PP mesh pores after operation is a major reason of hernia recurrence. Secondly, pre-operative prophylaxis during mesh implantation has failed due to the hydrophobic nature of PP meshes. Herein, chitosan cross-linked and levofloxacin HCl incorporated, antimicrobial PP mesh devices were prepared using citric acid as a bio-based and green cross-linking agent. The inert PP mesh fibers were surface activated using O2 plasma treatment at low pressure. Then, chitosan of different molecular weights (low and medium weight) were cross-linked with O2 plasma activated surfaces using citric acid. Scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy confirmed that chitosan was cross-linked with O2 plasma-treated PP mesh surfaces and formed a thin layer of chitosan and levofloxacin HCl on the PP mesh surfaces. Moreover, antimicrobial properties of chitosan and levofloxacin HCl-coated PP meshes were investigated using an agar plate release method. The coated PP meshes demonstrated excellent antimicrobial inhibition zone up to 10 mm. Thus, modified PP meshes demonstrated sustained antimicrobial properties for six continuous days against Staphylococcus aureus (SA) and Escherichia coli (EC) bacteria.

Polydopamine-Inspired Surface Modification of Polypropylene Hernia Mesh Devices via Cold Oxygen Plasma: Antibacterial and Drug Release Properties

Mesh infection is a major complication of hernia surgery after polypropylene (PP) mesh implantation. Modifying the PP mesh with antibacterial drugs is an effective way to reduce the chance of infection, but the hydrophobic characteristic of PP fibers has obstructed the drug adhesion. Therefore, to prepare antimicrobial PP mesh with a stable drug coating layer and to slow the drug release property during the hernia repair process has a great practical meaning. In this work, PP meshes were coated by bio-inspired polydopamine (PDA), which can load and release levofloxacin. PP meshes were activated with cold oxygen plasma and then plasma activated PP fibers were coated with PDA. The PDA coated meshes were further soaked in levofloxacin. The levofloxacin loaded PP meshes demonstrate excellent antimicrobial properties for 6 days and the drug release has lasted for at least 24 h. Moreover, a control PP mesh sample without plasma treatment was also prepared, after coating with PDA and loading levofloxacin. The antimicrobial property was sustained only for two days. The maximum inhibition zone of PDA coated meshes with and without plasma treatment was 12.5 and 9 mm, respectively. On all accounts, the modification strategy can facilely lead to long-term property of infection prevention.

A critical review of the in vitro and in vivo models for the evaluation of anti-infective meshes

BACKGROUND

Infectious complications following mesh implantation for abdominal wall repair appear in 0.7 up to 26.6% of hernia repairs and can have a detrimental impact for the patient. To prevent or to treat mesh-related infection, the scientific community is currently developing a veritable arsenal of antibacterial meshes. The numerous and increasing reports published every year describing new technologies indicate a clear clinical need, and an academic interest in solving this problem. Nevertheless, to really appreciate, to challenge, to compare and to optimize the antibacterial properties of next generation meshes, it is important to know which models are available and to understand them.

PURPOSE

We proposed for the first time, a complete overview focusing only on the in vitro and in vivo models which have been employed specifically in the field of antibacterial meshes for hernia repair.

RESULTS AND CONCLUSION

From this investigation, it is clear that there has been vast progress and breadth in new technologies and models to test them. However, it also shows that standardization or adoption of a more restricted number of models would improve comparability and be a benefit to the field of study.

Infections associated with mesh repairs of abdominal wall hernias: Are antimicrobial biomaterials the longed-for solution?

The incidence of mesh-related infection after abdominal wall hernia repair is low, generally between 1 and 4%; however, worldwide, this corresponds to tens of thousands of difficult cases to treat annually. Adopting best practices in prevention is one of the keys to reduce the incidence of mesh-related infection. Once the infection is established, however, only a limited number of options are available that provides an efficient and successful treatment outcome. Over the past few years, there has been a tremendous amount of research dedicated to the functionalization of prosthetic meshes with antimicrobial properties, with some receiving regulatory approval and are currently available for clinical use. In this context, it is important to review the clinical importance of mesh infection, its risk factors, prophylaxis and pathogenicity. In addition, we give an overview of the main functionalization approaches that have been applied on meshes to confer anti-bacterial protection, the respective benefits and limitations, and finally some relevant future directions.

Preparation and Characterization of Antibacterial Polypropylene Meshes with Covalently Incorporated β-Cyclodextrins and Captured Antimicrobial Agent for Hernia Repair

Polypropylene (PP) light weight meshes are commonly used as hernioplasty implants. Nevertheless, the growth of bacteria within textile knitted mesh intersections can occur after surgical mesh implantation, causing infections. Thus, bacterial reproduction has to be stopped in the very early stage of mesh implantation. Herein, novel antimicrobial PP meshes grafted with β-CD and complexes with triclosan were prepared for mesh infection prevention. Initially, PP mesh surfaces were functionalized with suitable cold oxygen plasma. Then, hexamethylene diisocyanate (HDI) was successfully grafted on the plasma-activated PP surfaces. Afterwards, β-CD was connected with the already HDI reacted PP meshes and triclosan, serving as a model antimicrobial agent, was loaded into the cyclodextrin (CD) cavity for desired antibacterial functions. The hydrophobic interior and hydrophilic exterior of β-CD are well suited to form complexes with hydrophobic host guest molecules. Thus, the prepared PP mesh samples, CD-TCL-2 and CD-TCL-6 demonstrated excellent antibacterial properties against Staphylococcus aureus and Escherichia coli that were sustained up to 11 and 13 days, respectively. The surfaces of chemically modified PP meshes showed dramatically reduced water contact angles. Moreover, X-ray diffractometer (XRD), differential scanning calorimeter (DSC), and Thermogravimetric (TGA) evidenced that there was no significant effect of grafted hexamethylene diisocyanate (HDI) and CD on the structural and thermal properties of the PP meshes.

Biodegradable rifampicin-releasing coating of surgical meshes for the prevention of bacterial infections

Polypropylene mesh implants are routinely used to repair abdominal wall defects or incisional hernia. However, complications associated with mesh implantation, such as mesh-related infections, can cause serious problems and may require complete surgical removal. Hence, the aim of the present study was the development of a safe and efficient coating to reduce postoperative mesh infections. Biodegradable poly(lactide-co-glycolide acid) microspheres loaded with rifampicin as an antibacterial agent were prepared through single emulsion evaporation method. The particle size distribution (67.93±3.39 μm for rifampicin-loaded microspheres and 64.43±3.61 μm for unloaded microspheres) was measured by laser diffraction. Furthermore, the encapsulation efficiency of rifampicin (61.5%±2.58%) was detected via ultraviolet–visible (UV/Vis) spectroscopy. The drug release of rifampicin-loaded microspheres was detected by UV/Vis spectroscopy over a period of 60 days. After 60 days, 92.40%±3.54% of the encapsulated rifampicin has been continuously released. The viability of BJ fibroblasts after incubation with unloaded and rifampicin-loaded microspheres was investigated using an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, which showed no adverse effects on the cells. Furthermore, the antibacterial impact of rifampicin-loaded microspheres and mesh implants, coated with the antibacterial microspheres, was investigated using an agar diffusion model with Staphylococcus aureus. The coated mesh implants were also tested in an in vivo mouse model of staphylococcal infection and resulted in a 100% protection against mesh implant infections or biofilm formation shown by macroscopic imaging, scanning electron microscopy, and histological examinations. This effective antibacterial mesh coating combining the benefit of a controlled drug delivery system and a potent antibacterial agent possesses the ability to significantly reduce postoperative implant infections.

Preparation and characterization of novel chitosan and β-cyclodextrin polymer sponges for wound dressing applications

Chitosan (CS) presents antibacterial, mucoadhesive and hemostatic properties and is an ideal candidate for wound dressing applications. This work reports the development of sponge-like materials obtained from physical hydrogels after the interaction between CS and a β-cyclodextrin polymer (PCD) in acidic conditions to provoke immediate gelation. Characterization consisted of zeta potential (ZP) measurements, rheology analysis, Fourier transform infrared (FTIR), Raman spectroscopy, wide angle X-ray scattering (WAXS) and scanning electron microscopy (SEM). Swelling behavior, cytotoxicity, drug sorption and drug delivery properties of sponges were assessed. ZP indicated that CS and PCD presented opposite charges needed for physical crosslinking. Rheology, swelling, and cytotoxicity of sponges depended on their CS:PCD weight ratios. Increasing PCD in the mixture delayed the gel time, reduced the swelling and increased the cytotoxicity. FTIR and Raman confirmed the physical crosslinking between CS and PCD through ionic interactions, and WAXS showed the amorphous state of the sponges. Finally, the efficiency of chlorhexidine loaded sponge against S. aureus bacteria was proved for up to 30days in agar diffusion tests.

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.

Poly(carboxylic acid)-Cyclodextrin/Anionic Porphyrin Finished Fabrics as Photosensitizer Releasers for Antimicrobial Photodynamic Therapy

In the development of new antibacterial therapeutic approaches to fight multidrug-resistant bacteria, antimicrobial photodynamic therapy (aPDT) represents a well-known alternative to treat local infections caused by different microorganisms. Here we present a polypropylene (PP) fabric finished with citrate-hydroxypropyl-βCD polymer (PP-CD) entrapping the tetra-anionic 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphine (TPPS) as photosensitizer-eluting scaffold (PP-CD/TPPS) for aPDT. The concept is based on host-guest complexation of porphyrin in the cavities of CDs immobilized on the PP fibers, followed by its sustained and controlled delivery in release medium and simultaneous photoinactivation of microorganisms. Morphology of fabric was characterized by optical (OM) and scanning electron microscopies (SEM). Optical properties were investigated by UV-vis absorption, steady- and time-resolved fluorescence emission spectroscopy. X-ray photoelectron spectroscopy (XPS) and FT-IR revealed the surface chemical composition and the distribution map of the molecular components on the fabric, respectively. Direct ¹O₂ determination allowed to assess the potential photodynamic activity of the fabric. Release kinetics of TPPS in physiological conditions pointed out the role of the CD cavity to control the TPPS elution. Photoantimicrobial activity of the porphyrin-loaded textile was investigated against both Gram-positive Staphylococcus aureus ATCC 29213 (S. aureus) and Gram-negative Pseudomonas aeruginosa ATCC 27853 (P. aeruginosa). Optical microscopy coupled with UV-vis extinction and fluorescence spectra aim to ascertain the uptake of TPPS to S. aureus bacterial cells. Finally, PP-CD/TPPS fabric-treated S. aureus cells were photokilled of 99.98%. Moreover, low adhesion of S. aureus cells on textile was established. Conversely, no photodamage of fabric-treated P. aeruginosa cells was observed, together with their satisfying adhesion.

Emerging technologies for long-term antimicrobial device coatings: advantages and limitations

Over the past 20 years, the field of antimicrobial medical device coatings has expanded nearly 30-fold with technologies shifting their focus from diffusion-only based (short-term antimicrobial eluting) coatings to long-term antimicrobial eluting and intrinsically antimicrobial functioning materials. A variety of emergent coatings have been developed with the goal of achieving long-term antimicrobial activity in order to mitigate the risk of implanted device failure. Specifically, the coatings can be grouped into two categories: those that use antibiotics in conjunction with a polymer coating and those that rely on the intrinsic properties of the material to kill or repel bacteria that come into contact with the surface. This review covers both long-term drug-eluting and non-eluting coatings and evaluates the inherent advantages and disadvantages of each type while providing an overview of variety applications that the coatings have been utilized in. Impact statement This work provides an overview, with advantages and limitations of the most recently developed antibacterial coating technologies, enabling other researchers in the field to more easily determine which technology is most advantageous for them to further develop and pursue.

Cytocompatibility testing of cyclodextrin-functionalized antimicrobial textiles-a comprehensive approach

Functionalized textiles can be used in wound management to reduce the microbial burden in the wound area, to prevent wound infections, and to avoid cross-contamination between patients. In the present study, a comprehensive in vitro approach to enable the assessment of antibacterial activity of functionalized textiles and cytotoxicity of cyclodextrin (CD)-complexes with chlorhexidine diacetate (CHX), iodine (IOD), and polihexanide (PHMB) is suggested to evaluate their properties for supporting optimal conditions for wound healing. For all β-CD-antiseptic functionalized cotton samples a strong antibacterial effect on the Gram-positive bacteria Staphylococcus aureus and Staphylococcus epidermidis as well as on the Gram-negative bacteria Klebsiella pneumoniae and Escherichia coli was proven. In addition, β-CD-CHX and β-CD-PHMB were effective against the yeast Candida albicans. The growth of Pseudomonas aeruginosa could be reduced significantly by β-CD-IOD and β-CD-PHMB. The established comprehensive testing system for determination of biocompatibility on human HaCaT keratinocytes is suitable for obtaining robust data on cell viability, cytotoxicity and mode of cell death of the β-CD-antiseptic-complexes. The promising results of the high antimicrobial activity of these functionalized textiles show the high potential of such materials in medical applications.

Evaluation of the Antimicrobial Efficacy of a Novel Rifampin/Minocycline-Coated, Noncrosslinked Porcine Acellular Dermal Matrix Compared With Uncoated Scaffolds for Soft Tissue Repair

Background Despite meticulous aseptic technique and systemic antibiotics, bacterial colonization of mesh remains a critical issue in hernia repair. A novel minocycline/rifampin tyrosine-coated, noncrosslinked porcine acellular dermal matrix (XenMatrix AB) was developed to protect the device from microbial colonization for up to 7 days. The objective of this study was to evaluate the in vitro and in vivo antimicrobial efficacy of this device against clinically isolated methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli. Methods XenMatrix AB was compared with 5 existing uncoated soft tissue repair devices using in vitro methods of zone of inhibition (ZOI) and scanning electron microscopy (SEM) at 24 hours following inoculation with MRSA or E coli These devices were also evaluated at 7 days following dorsal implantation and inoculation with MRSA or E coli (60 male New Zealand white rabbits, n = 10 per group) for viable colony-forming units (CFU), abscess formation and histopathologic response, respectively. Results In vitro studies demonstrated a median ZOI of 36 mm for MRSA and 16 mm for E coli for XenMatrix AB, while all uncoated devices showed no inhibition of bacterial growth (0 mm). SEM also demonstrated no visual evidence of MRSA or E coli colonization on the surface of XenMatrix AB compared with colonization of all other uncoated devices. In vivo XenMatrix AB demonstrated complete inhibition of bacterial colonization, no abscess formation, and a reduced inflammatory response compared with uncoated devices. Conclusion We demonstrated that XenMatrix AB possesses potent in vitro and in vivo antimicrobial efficacy against clinically isolated MRSA and E coli compared with uncoated devices.

Determination of the glass transition temperature of cyclodextrin polymers

The aim of this work was to determine the main physical characteristics of β-cyclodextrin polymers, well known for improving complexation capacities and providing enhanced and sustained release of a large panel of drugs. Two polymers were investigated: a polymer of β-cyclodextrin (polyβ-CD) and a polymer of partially methylated (DS=0.57) β-cyclodextrin (polyMe-β-CD). The physical characterizations were performed by powder X-ray diffraction and differential scanning calorimetry. The results indicate that these polymers are amorphous and that their glass transition is located above the thermal degradation point of the materials preventing their direct observation and thus their full characterization. We could however estimate the virtual glass transition temperatures by mixing the polymers with different plasticizers (trehalose and mannitol) which decreases Tg sufficiently to make the glass transition observable. Extrapolation to zero plasticizer concentration then yield the following Tg values: Tg (polyMe-β-CD)=317°C±5°C and Tg (polyβ-CD)=418°C±6°C.

Water-soluble cationic poly(β-cyclodextrin-co-guanidine) as a controlled vitamin B2delivery carrier

Vitamin B₂(VB₂) is effectively incorporated into novel water-soluble cationic β-cyclodextrin (β-CD) polymers in order to improve its physiochemical properties.

Mesh Infection and Hernia Repair: A Review

BACKGROUND

The use of a prosthetic mesh to repair a tissue defect may produce a series of post-operative complications, among which infection is the most feared and one of the most devastating. When occurring, bacterial adherence and biofilm formation on the mesh surface affect the implant's tissue integration and host tissue regeneration, making preventive measures to control prosthetic infection a major goal of prosthetic mesh improvement.

METHODS

This article reviews the literature on the infection of prosthetic meshes used in hernia repair to describe the in vitro and in vivo models used to examine bacterial adherence and biofilm formation on the surface of different biomaterials. Also discussed are the prophylactic measures used to control implant infection ranging from meshes soaked in antibiotics to mesh coatings that release antimicrobial agents in a controlled manner.

RESULTS

Prosthetic architecture has a direct effect on bacterial adherence and biofilm formation. Absorbable synthetic materials are more prone to bacterial colonization than non-absorbable materials. The reported behavior of collagen biomeshes, also called xenografts, in a contaminated environment has been contradictory, and their use in this setting needs further clinical investigation. New prophylactic mesh designs include surface modifications with an anti-adhesive substance or pre-treatment with antibacterial agents or metal coatings.

CONCLUSIONS

The use of polymer coatings that slowly release non-antibiotic drugs seems to be a good strategy to prevent implant contamination and reduce the onset of resistant bacterial strains. Even though the prophylactic designs described in this review are mainly focused on hernia repair meshes, these strategies can be extrapolated to other implantable devices, regardless of their design, shape or dimension.

Emerging Trends in Abdominal Wall Reinforcement: Bringing Bio-Functionality to Meshes

Abdominal wall hernia is a recurrent issue world-wide and requires the implantation of over 1 million meshes per year. Because permanent meshes such as polypropylene and polyester are not free of complications after implantation, many mesh modifications and new functionalities have been investigated over the last decade. Indeed, mesh optimization is the focus of intense development and the biomaterials utilized are now envisioned as being bioactive substrates that trigger various physiological processes in order to prevent complications and to promote tissue integration. In this context, it is of paramount interest to review the most relevant bio-functionalities being brought to new meshes and to open new avenues for the innovative development of the next generation of meshes with enhanced properties for functional abdominal wall hernia repair.

Bioinspired Titanium Drug Eluting Platforms Based on a Poly-β-cyclodextrin-Chitosan Layer-by-Layer Self-Assembly Targeting Infections

In the field of implantable titanium-based biomaterials, infections and inflammations are the most common forms of postoperative complications. The controlled local delivery of therapeutics from implants through polyelectrolyte multilayers (PEMs) has recently emerged as a versatile technique that has shown great promise in the transformation of a classical medical implant into a drug delivery system. Herein, we report the design and the elaboration of new biodegradable multidrug-eluting titanium platforms based on a polyelectrolyte multilayer bioactive coating that target infections. These systems were built up in mild conditions according to the layer-by-layer (L-b-L) assembly and incorporate two biocompatible polysaccharides held together through electrostatic interactions. A synthetic, negatively charged β-cyclodextrin-based polymer (PCD), well-known for forming stable and reversible complexes with hydrophobic therapeutic agents, was exploited as a multidrug reservoir, and chitosan (CHT), a naturally occurring, positively charged polyelectrolyte, was used as a barrier for controlling the drug delivery rate. These polyelectrolyte multilayer films were strongly attached to the titanium surface through a bioinspired polydopamine (PDA) film acting as an adhesive first layer and promoting the robust anchorage of PEMs onto the biomaterials. Prior to the multilayer film deposition, the interactions between both oppositely charged polyelectrolytes, as well the multilayer growth, were monitored by employing surface plasmon resonance (SPR). Several PEMs integrating 5, 10, and 15 bilayers were engineered using the dip coating strategy, and the polyelectrolyte surface densities were estimated by colorimetric titrations and gravimetric analyses. The morphologies of these multilayer systems, as well as their naturally occurring degradation in a physiological medium, were investigated by scanning electron microscopy (SEM), and their thicknesses were measured by means of profilometry and ellipsometry studies. Finally, the ability of the coated titanium multilayer devices to act as a drug-eluting system and to treat infections was validated with gentamicin, a relevant water-soluble antibiotic commonly used in medicine due to its broad bactericidal spectrum.

Chitosan finishing nonwoven textiles loaded with silver and iodide for antibacterial wound dressing applications

Polyethylene terephtalate (PET) and Polypropylene (PP) textiles are widely used in biomedical application such as wound dressings and implants. The aim of this work was to develop an antibacterial chitosan (CHT) coating activated by silver or by iodine. Chitosan was immobilized onto PET and PP supports using citric acid (CTR) as a crosslinking agent through a pad-dry-cure textile finishing process. Interestingly, depending on the CHT/CTR molar ratio, two different systems were obtained: rich in cationic ammonium groups when the CTR concentration was 1%w/v, and rich in anionic carboxylate groups when the CTR concentration was 10%w/v. As a consequence, such samples could be selectively loaded with iodine and silver nitrate, respectively.Both types of coatings were analyzed using SEM and FTIR, their sorption capacities were evaluated toward iodide/iodate anions (I(-)/IO3(-)) and the silver cations (Ag(+)) were evaluated using elemental analysis. Finally, in vitro evaluations were carried out to evaluate the cytocompatibility on the epithelial cell line. The silver loaded textile reported a stronger antibacterial effect against E.coli (5 log10 reduction) than toward S. aureus (3 log10) while the antibacterial effect of the iodide loaded textiles was limited to 1 log10 to 2 log10 on both strains.

Visceral mesh modified with cyclodextrin for the local sustained delivery of ropivacaine

The aim of the study was to develop a polyester visceral implant modified with a cyclodextrin polymer for the local and prolonged delivery of ropivacaine to reduce post operatory pain. Therefore, we applied a coating of an inguinal mesh with a crosslinked polymer of hydroxypropyl-β-cyclodextrin (HPβCD) whose specific host-guest complex forming properties were expected to improve the adsorption capacity of the implant toward anesthetic, and then to release it within a sustained period. The modification reaction of the textile with cyclodextrin was explored through the study of the influence of the pad/dry/cure process parameters and the resulting implant (PET-CD) was characterized by solid state NMR and SEM. Besides, the inclusion complex between ropivacaine and CD was studied by NMR and capillary electrophoresis in PBS medium. Finally, ropivacaine sorption test showed that a maximum of 30 mg/g of ropivacaine could be adsorbed on the functionalized samples. In dynamic batch tests in PBS at pH 7.4, the release could be observed up to 6h. The cytocompatibility of the PET-CD loaded with ropivacaine was also studied and reached 65% cell vitality after 6 days.

Mussel inspired coating of a biocompatible cyclodextrin based polymer onto CoCr vascular stents

During the past decade, drug-eluting stents (DES) have been widely used for the treatment of occlusive coronary artery diseases. They are supposed to reduce the incidence of early in-stent restenosis by the elution of highly hydrophobic antiproliferative drugs. Nevertheless, the absence of long-term activity of these devices is responsible for late acute thrombosis probably due to the delayed re-endothelialization of the arterial wall over the bare metallic stent struts. Thus, a new generation of DES with a sustained release of therapeutic agents is required to improve long-term results of these devices. In this article, we report an original functionalization of CoCr vascular devices with a hydrophilic, biocompatible and biodegradable cyclodextrins based polymer which acts as a reservoir for lipophilic drugs allowing the sustained release of antiproliferative drugs. In this setting, polydopamine (PDA), a strong adhesive biopolymer, was applied as a first coating layer onto the surface of the metallic CoCr device in order to promote the strong anchorage of a cyclodextrin polymer. This polymer was generated "in situ" from the methylated cyclodextrins and citric acid as a cross-linking agent through a polycondensation reaction. After optimization of the grafting process, the amount of cyclodextrin polymer coated onto the CoCr device was quantified by colorimetric titrations and the resulting film was characterized by scanning electron microscopy (SEM) investigations. The cytocompatibility of the resulting coated film was assessed by cell proliferation and vitality tests. Finally, the ability of this coated device to act as a drug-eluting system was evaluated with paclitaxel, a strong hydrophobic antiproliferative drug, a reference drug used in current vascular drug-eluting stents.

A chlorhexidine-loaded biodegradable cellulosic device for periodontal pockets treatment

Absorbent points widely used in endodontic therapy were transformed into bioresorbable chlorhexidine delivery systems for the treatment of the periodontal pocket by preventing its recolonization by the subgingival microflora. These paper points (PPs) were first oxidized to promote their resorption, then grafted with β-cyclodextrin (CD) or maltodextrin (MD) in order to achieve sustained delivery of chlorhexidine. We investigated the oxidation step parameters through the time of reaction and the nitric and phosphoric acid ratios in the oxidizing mixture, and then the dextrin grafting step parameters through the time and temperature of reaction. A first selection of the appropriate functionalization parameters was undertaken in relation to the degradation profile kinetics of the oxidized (PPO) and oxidized-grafted samples (PPO-CD and PPO-MD). Samples were then loaded with chlorhexidine digluconate (digCHX), a widely used antiseptic agent in periodontal therapy. The release kinetics of digCHX from PPO-CD and PPO-MD samples were compared to PP, PPO and to PerioChip(®) (a commercial digCHX containing gelatine chip) in phosphate buffered saline (pH 7.4) by ultraviolet spectrophotometry. The cytocompatibility of the oxidized-grafted PP was demonstrated by cell proliferation assays. Finally, the disc diffusion test from digCHX loaded PPO-MD samples immersed in human plasma was developed on pre-inoculated agar plates with four common periodontal pathogenic strains: Fusobacterium nucleatum, Prevotella melaninogenica, Aggregatibacter actinomycetem comitans and Porphyromonas gingivalis. To conclude, the optimized oxidized-dextrin-grafted PPs responded to our initial specifications in terms of resorption and digCHX release rates and therefore could be adopted as a reliable complementary periodontal therapy.

Chemically cross-linked and grafted cyclodextrin hydrogels: from nanostructures to drug-eluting medical devices

The unique ability of cyclodextrins (CDs) to form inclusion complexes can be transmitted to polymeric networks in which CDs are chemically grafted or cross-linked. Combination of CDs and hydrogels in a single material leads to synergic properties: the hydrophilic network enhances biocompatibility and prevents dilution in the physiological medium increasing the stability of the inclusion complexes, while CDs finely tune the mechanical features and the stimuli-responsiveness and provide affinity-based regulation of drug loading and release. Therefore, CD-functionalized materials are opening new perspectives in pharmacotherapy, emerging as advanced delivery systems (DDS) for hydrophobic and hydrophilic drugs to be administered via almost any route. Medical devices (catheters, prosthesis, vascular grafts, bone implants) can also benefit from surface grafting or thermofixation of CDs. The present review focuses on the approaches tested to synthesize nano- to macro-size covalently cross-linked CD networks: i) direct cross-linking through condensation with di- or multifunctional reagents, ii) copolymerization of CD derivatives with acrylic/vinyl monomers, and iii) grafting of CDs to preformed medical devices. Examples of the advantages of having the CDs chemically bound among themselves and to substrates are provided and their applicability in therapeutics discussed.

Low-density polypropylene meshes coated with resorbable and biocompatible hydrophilic polymers as controlled release agents of antibiotics

The application of bioactive meshes in abdominal surgery for the repair of hernias is an increasing clinical activity in a wide sector of the population. The main secondary effect is the appearance of infections from bacteria, specifically Staphylococcus aureus and S. epidermidis. This paper describes the development and application of low-density polypropylene meshes coated with a biocompatible and resorbable polymer as a controlled release system of the antibiotic vancomycin. The polymeric coating (a non-cross-linked copolymer of 2-hydroxyethyl methacrylate and 2-acrylamido-2-methylpropanesulfonic acid) has a thickness of 14-15μm and contains 0.32mgcm(-2) of the antibiotic vancomycin. The in vitro experiments demonstrate the excellent inhibitory character of the coated meshes loaded with the antibiotic, following the standard protocol of inhibition of halo in agar diffusion test. This inhibitory effect is maintained for a relatively long period (at least 14days) with a low concentration of antibiotic. The acrylic polymer system regulates the release of the antibiotic with a rate of 24μgh(-1), due to its slow dissolution in the medium. Experiments in vivo, based on the implantation of coated meshes, demonstrate that the system controls the infection in the animal (rabbits) for at least 30days. The concentration of antibiotic in the blood stream of the rabbits was below the detection limit of the analytical technique (<1-2μgml(-1)), which demonstrates that the antibiotic is released in the local area of the implant and remains concentrated at the implantation site, without diffusion to the blood stream. The systems can be applied to other medical devices and implants for the application of new-generation antibiotics in a controlled release and targeted applications.