A chlorhexidine-loaded biodegradable cellulosic device for periodontal pockets treatment

Fabrication and characterization of chlorhexidine gluconate loaded poly(vinyl alcohol)/45S5 nano-bioactive glass nanofibrous membrane for guided tissue regeneration applications

Polymeric barrier membranes are used in periodontal applications to prevent fibroblastic cell migration into the cavities of bone tissue and to properly guide the proliferation of tissues. In this study, the fabrication, characterization, bioactivity, and in vitro biological properties of polyvinyl alcohol-based nanofibrous membranes containing nano-sized 45S5 bioactive glass (BG) loaded with chlorhexidine (CH) gluconate with biocompatible, bioactive, and antibacterial properties for using as dental barrier membranes were investigated. Nanofibrous membranes with an average fiber diameter, pore size, and porosity of 210 nm, 24.73 μm, and 12.42%, respectively, were loaded with 1% and 2% CH, and the release profile was investigated. The presence of BG in the membranes promoted fibroblastic proliferation and the presence of CH provided antibacterial properties. Nanofibrous membranes exhibit a high ability to restrict bacterial growth while fulfilling the necessary conditions for use as a dental barrier thanks to their low swelling rates, significant surface bioactivities, and appropriate degradation levels.

Hybrid Hydrogel Loaded with Chlorhexidine⊂β-CD-MSN Composites as Wound Dressing

Background

Much attention has been paid to sustained drug release and anti-infection in wound management. Hydrogels, which are biocompatible materials, are promising tools for controlled drug release and infective protection during wound healing. However, hydrogels also demonstrate limitations in the highly efficient treatment of wounds because of the diffusion rate. In this work, we explored pH-sensitive hydrogels that enable ultra-long-acting drug release and sustained antibacterial properties.

Methods

We constructed a hybrid gelatin methacrylate (GelMA) system with sustainable antibacterial properties combining hyaluronic acid (HA)-coated mesoporous silica nanoparticles (MSN), which loaded host-guest complexes of chlorhexidine (CHX) with β-cyclodextrins (β-CD) (CHX⊂CD-MSN@HA@GelMA). The release mechanism of CHX was explored using UV-vis spectra after intermittent diffusion of CHX. The hybrid hydrogels were characterized, and the drug content in terms of the release profile, bacterial inhibition, and in vivo experiments were investigated.

Results

Except for dual protection from both hydrogels, MSN in the HA improved the drug loading efficiency to promote the local drug concentration. It showed that complicated CHX-loaded MSN releases CHX more gradually and over a longer duration than CHX-loaded MSNs. This demonstrated a 12-day CHX release time and antibacterial activity, primarily attributable to the capacity of β-CD to form an inclusion complex with CHX. Meanwhile, in vivo experiments revealed that the hydrogels safely promote skin wound healing and enhance therapeutic efficacy.

Conclusion

We constructed pH-sensitive CHX⊂CD-MSN@HA@GelMA hydrogels that enable ultra-long-acting drug release and sustained antibacterial properties. The combination of β-CD and MSN would be better suited to release a reduced rate of active molecules over time (slow delivery), making them great candidates for wound dressing anti-infection materials.

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.

Harnessing biomolecules for bioinspired dental biomaterials

Dental clinicians have relied for centuries on traditional dental materials (polymers, ceramics, metals, and composites) to restore oral health and function to patients. Clinical outcomes for many crucial dental therapies remain poor despite many decades of intense research on these materials. Recent attention has been paid to biomolecules as a chassis for engineered preventive, restorative, and regenerative approaches in dentistry. Indeed, biomolecules represent a uniquely versatile and precise tool to enable the design and development of bioinspired multifunctional dental materials to spur advancements in dentistry. In this review, we survey the range of biomolecules that have been used across dental biomaterials. Our particular focus is on the key biological activity imparted by each biomolecule toward prevention of dental and oral diseases as well as restoration of oral health. Additional emphasis is placed on the structure-function relationships between biomolecules and their biological activity, the unique challenges of each clinical condition, limitations of conventional therapies, and the advantages of each class of biomolecule for said challenge. Biomaterials for bone regeneration are not reviewed as numerous existing reviews on the topic have been recently published. We conclude our narrative review with an outlook on the future of biomolecules in dental biomaterials and potential avenues of innovation for biomaterial-based patient oral care.

Evaluation of antibacterial textile covered by layer-by-layer coating and loaded with chlorhexidine for wound dressing application

The aim of this work is to design a wound dressing able to release chlorhexidine (CHX) as antiseptic agent, ensuring long-lasting antibacterial efficacy during the healing. The textile nonwoven (polyethylene terephthalate) (PET) of the dressing was first modified by chitosan (CHT) crosslinked with genipin (Gpn). Parameters such as the concentration of reagents (Gpn and CHT) but also the crosslinking time and the working temperature were optimized to reach the maximal positive charges surface density. This support was then treated by the layer-by-layer (LbL) deposition of a multilayer system composed of methyl-beta-cyclodextrin polymer (PCD) (anionic) and CHT (cationic). After a thermal treatment to stabilize the LbL film, the textiles were loaded with CHX as antiseptic agent. The influence of the thermal treatment i) on the cytocompatibility, ii) on the degradation of the multilayer system, iii) on CHX sorption and release profiles and iv) on the antibacterial activity of the loaded textiles was studied.

Glass ionomer cements with milled, dry chlorhexidine hexametaphosphate filler particles to provide long-term antimicrobial properties with recharge capacity

OBJECTIVE

Glass ionomer cements (GICs) are a versatile material, offering the opportunity for ion exchange with the oral environment. The aim of this study was to develop a GIC that delivers a controlled, rechargeable dose of chlorhexidine (CHX) over an extended period without compromising mechanical properties.

METHODS

GICs were supplemented with finely milled particles of chlorhexidine hexametaphosphate (CHX-HMP). CHX release into artificial saliva was measured over 660 days, and recharge with CHX and CHX-HMP was investigated. Mechanical properties were investigated, and an agar diffusion test was carried out to assess antimicrobial properties using Streptococcus mutans and Scardovia wiggsiae.

RESULTS

Dose-dependent CHX release was observed, and this was ongoing at 660 days. Compared with related studies of GICs containing CHX-HMP, the fine, dry particles resulted in fewer adverse effects on mechanical properties, including tensile, compressive and biaxial flexural strength, with 1% CHX-HMP GICs indistinguishable from control specimens. The GICs could be recharged with CHX using both a conventional CHX digluconate solution comparable to commercial mouthrinses, and a suspension of CHX-HMP of equivalent concentration. Recharging with CHX digluconate increased subsequent CHX release by 50% compared with no recharge, and recharging with CHX-HMP increased subsequent CHX release by 100% compared with no recharge. The GICs inhibited growth of St. mutans and Sc. wiggsiae in a simple agar diffusion model.

SIGNIFICANCE

These materials, which provide sustained CHX release over clinically relevant timescales, may find application as a restorative material intended to inhibit secondary caries as well as in temporary restorations and fissure sealants.

Electrospun poly(lactic acid) fibers containing novel chlorhexidine particles with sustained antibacterial activity

The treatment of persistent infections often requires a high local drug concentration and sustained release of antimicrobial agents. This paper proposes the use of novel electrospinning of poly(lactic acid) (PLA) fibers containing uncoated and encapsulated chlorhexidine particles. Chlorhexidine particles with a mean (SD) diameter of 17.15 ± 1.99 μm were fabricated by the precipitation of chlorhexidine diacetate with calcium chloride. Layer-by-layer (LbL) encapsulation of the chlorhexidine particles was carried out to produce encapsulated particles. The chlorhexidine particles had a high chlorhexidine content (90%), and when they were electrospun into PLA fibers a bead-in-string structure was obtained. The chlorhexidine content in the fibers could be tuned and a sustained release over 650 h was produced, via chlorhexidine particle encapsulation. Chlorhexidine release was governed by the polyelectrolyte multilayer encapsulation as demonstrated by SEM and confocal imaging. The incorporation of uncoated and encapsulated chlorhexidine particles (0.5% and 1% wt/wt chlorhexidine) into the fibers did not cause toxicity to healthy fibroblasts or affect cell adhesion to the fibers over a period of 5 days. The chlorhexidine-containing fibers also demonstrated sustained antibacterial activity against E. coli via an agar diffusion assay and broth transfer assay. Therefore, the chlorhexidine-containing PLA fibers may be useful in the treatment of persistent infections in medicine and dentistry.

Controlled release of chlorhexidine from a HEMA-UDMA resin using a magnetic field

OBJECTIVES

To functionalize novel chlorhexidine (CHX) particles with iron oxide (Fe₃O₄) nanoparticles and control their release kinetics in a dental resin using an external magnetic field.

METHODS

Fe₃O₄ nanoparticles were synthesized and incorporated into spherical CHX particles and the powder was freeze dried. Resin disc specimens were produced using a UDMA-HEMA resin mixed with freeze dried spherical Fe₃O₄-CHX particles (5wt.%), which were placed into a Teflon mould (10mm diameter×1mm depth) and covered with a Mylar strip. A MACS magnet was left in contact for 0min (Group 1), 5min (Group 2) or 10min (Group 3) and the resin discs subsequently light cured (Bluedent LED pen, Bulgaria) for 60s per side. The resin discs were immersed in deionized water at various time points up to 650h. UV-Vis absorbance was used to determine the CHX content. CHX released for each time point was determined. The functionalized CHX particles and resin discs were characterized using TEM, TGA, EDX and SEM.

RESULTS

Fe₃O₄ nanoparticles (20nm) incorporated into the spherical CHX particles led to a mean (SD) particle size reduction from 17.15 (1.99)μm to 10.39 (2.61)μm. The presence of Fe₃O₄ nanoparticles in the spherical CHX particles was confirmed with SEM, EDX, and TGA. SEM of Group 1 resin discs (no magnetic exposure) showed functionalized CHX spheres were homogeneously distributed within the resin discs. For resin discs which had magnetic exposure (5 or 10min) the particles started to cluster nearer the surface (Group 2: 43.7%, Group 3: 57.3%), to a depth of 94μm. UV-Vis absorbance revealed Group 1 resin discs had a cumulative CHX release of 4.4% compared to 5.9% for Group 2 and 7.4% for Group 3 resin discs, which had magnetic exposure (5, 10min).

SIGNIFICANCE

Fe₃O₄ nanoparticle functionalized CHX spheres demonstrated a magnetic field responsive property. A magnetic field responsive release of CHX may be useful in clinical situations where the drug can be directed to give a tailored release at the site of infection.

Gold Nanorod Mediated Chlorhexidine Microparticle Formation and Near-Infrared Light Induced Release

Gold nanorods (GNR) are good light harvesting species for elaboration of near-infrared (NIR) responsive drug delivery systems. Herein, chlorhexidine microparticles are grown directly on the surface of gold nanorods and then stabilized with polyelectrolyte multilayer encapsulation, producing novel composite drug-GNR particles with high drug loading and NIR light sensitivity. Crystallization of chlorhexidine is caused by the ionic strength of the chloride solution that has been demonstrated via formation of a homogeneous porous spherical structure at 0.33 M CaCl₂. By introducing GNRs into the CaCl₂ solution, the nucleation of chlorhexidine molecules and size of produced spheres are affected, since GNRs act as sites for chlorhexidine nucleation. Similarly, when GNRs are replaced by chlorhexidine seeds (5.2 ± 1.7 μm), a core-shell crystal structure is observed. The encapsulated GNR/chlorhexidine composites are responsive to NIR light (840 nm) that increases the temperature at the chlorhexidine crystals, followed by microparticle dissolution and rupture of capsules which is illustrated with confocal microscopy and SEM. Furthermore, a stepwise burst release of chlorhexidine can be induced by multiple cycles of NIR light exposure. The GNR/chlorhexidine composites show good biocompatibility and antimicrobial activity. The proposed method of antibacterial drug release may therefore indicate that this NIR responsive chlorhexidine composite may be useful for future clinical applications.

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.

[When textiles help your recovery]

Textiles are widely used in the biomedical domain, particularly in wound dressings or as implantable devices for strengthening or even replacing some damaged organs. Nowadays they present more and more sophisticated functionalities contributing to the healing process, to the organs regeneration, and fight against infection or thrombosis. Advanced spinning technologies of biostable or bioresorbable polymers and surface treatment technologies are often used, as well as nanotechnologies, to implement two main strategies for development of bio-active textiles. A long or medium term technology is obtained by grafting the bio-active molecule through stable chemical bonds while a short term activity is produced by using "reservoir" systems such as hydrogels and cyclodextrins that release the active agents in situ. ‡.

Chlorhexidine Loaded Cyclodextrin Containing PMMA Nanogels as Antimicrobial Coating and Delivery Systems

Antimicrobial nanogels, aggregates, and films are prepared by complexation of the antiseptic and bacteriostatic agent chlorhexidine (CHX) for medical and dental applications. A series of α-, β-, and γ-cyclodextrin methacrylate (CD-MA) containing hydrophobic poly(methyl methacrylate) (PMMA) based nanogels are loaded quantitatively with CHX in aqueous dispersion. The results show that CHX is enhancedly complexed by the use of CD-MA domains in the particles structure. β-CD-MA nanogels present the highest uptake of CHX. Furthermore, it is observed that the uptake of CHX in nanogels is influenced by the hydrophobic PMMA structure. CHX acts as external cross-linker of nanogels by formation of 1:2 (CHX:CD-MA) inclusion complexes of two β-CD-MA units on the surfaces of two different nanogels. The nanogels adsorb easily onto glass surfaces by physical self-bonding and formation of a dense crosslinked nanogel film. Biological tests of the applied CHX nanogels with regard to antimicrobial efficiency are successfully performed against Staphylococcus aureus.

New multifunctional pharmaceutical excipient in tablet formulation based on citric acid-cyclodextrin polymer

A β-cyclodextrin (β-CD) polymer obtained by crosslinking β-CD with citric acid in its water-insoluble (PCD-I) and soluble (PCD-S) forms was used as a multifunctional direct compression excipient for tablet designing. PCD-I powder was obtained after grinding the solid fraction through a 200μm grid. PCD-S powder was recovered after lyophilization or spray drying of the PCD-S aqueous solutions, eventually followed by a wet granulation step. Both PCD-I and PCD-S powders were characterized, separately and mixed in variable ratios, based on dynamic water vapor sorption, SEM, particle size distribution, tapped density, compressibility, and flowability. PCD-I and spray dried and lyophilized/wet granulated PCD-S, as well as the mixture PCD-I/PCD-S=90/10, presented optimal free flowing characteristics. Then, PCD-I or PCD-S powders - separately or mixed in variable ratios - were used for tablets preparation by direct compression without adding any other excipient (e.g. binder, lubricant, disintegrant etc). As PCD-I decreased, tablets resistance to crushing and disintegration time increased from 15s to 15min (against 30min for β-CD), showing the improved disintegrant functionality of PCD-I, that rapidly swelled once in contact with water. Finally, PCD was force-fed to Sprague-Dawley rats (2g/kg) which were then observed during 14days for any clinical signs of toxicity.

Novel Formulation of Chlorhexidine Spheres and Sustained Release with Multilayered Encapsulation

This work demonstrates the synthesis of new chlorhexidine polymorphs with controlled morphology and symmetry, which were used as a template for layer-by-layer (LbL) encapsulation. LbL self-assembly of oppositely charged polyelectrolytes onto the drug surface was used in the current work, as an efficient method to produce a carrier with high drug content, improved drug solubility and sustained release. Coprecipitation of the chlorhexidine polymorphs was performed using chlorhexidine diacetate and calcium chloride solutions. Porous interconnected chlorhexidine spheres were produced by tuning the concentration of calcium chloride. The size of these drug colloids could be further controlled from 5.6 μm to over 20 μm (diameter) by adjusting the coprecipitation temperature. The chlorhexidine content in the spheres was determined to be as high as 90%. These particles were further stabilized by depositing 3.5 bilayers of poly(allylamine hydrochloride) (PAH) and polystyrenesulfonate (PSS) on the surface. In vitro release kinetics of chlorhexidine capsules showed that the multilayer shells could prolong the release, which was further demonstrated by characterizing the remaining chlorhexidine capsules with SEM and confocal microscopy. The new chlorhexidine polymorph and LbL coating has created novel chlorhexidine formulations. Further modification to the chlorhexidine polymorph structure is possible to achieve both sustained and stimuli responsive release, which will enhance its clinical performance in medicine and dentistry.

Preparation and Tribological Study of Biodegradable Lubrication Films on Si Substrate

A novel method for preparing eco-biodegradable lubricant based on hydroxypropyl methylcellulose (HPMC) via hydration process is demonstrated. The smooth and homogeneous HPMC coating has a uniform thickness (~35 μm). It has been demonstrated that the preparation parameters play a critical role in controlling the lubricating behavior of the coating; in addition, excess HPMC and water concentration suppress the tribology properties. Nevertheless, a remarkable friction-reduction and anti-wear performance has been obtained. Impressively, the preparation parameter of 5% HPMC + 30 mL water significantly improves lubricant performance and durability. A simple approach for the water-degradability evaluation of HPMC is proposed.

Polymeric nanoarchitectures on Ti-based implants for antibacterial applications

Because of the excellent mechanical properties and good biocompatibility, titanium-based metals are widely used in hard tissue repair, especially load-bearing orthopedic applications. However, bacterial infection and complication during and after surgery often causes failure of the metallic implants. To endow titanium-based implants with antibacterial properties, surface modification is one of the effective strategies. Possessing the unique organic structure composed of molecular and functional groups resembling those of natural organisms, functionalized polymeric nanoarchitectures enhance not only the antibacterial performance but also other biological functions that are difficult to accomplish on many conventional bioinert metallic implants. In this review, recent advance in functionalized polymeric nanoarchitectures and the associated antimicrobial mechanisms are reviewed.