In vitro and in vivo degradation behaviors of synthetic absorbable bicomponent monofilament suture prepared with poly(p-dioxanone) and its copolymer

Electrospun Medical Sutures for Wound Healing: A Review

With the increasing demand for wound healing around the world, the level of medical equipment is also increasing, but sutures are still the preferred medical equipment for medical personnel to solve wound closures. Compared with the traditional sutures, the nanofiber sutures produced by combining the preparation technology of drug-eluting sutures have greatly improved both mechanical properties and biological properties. Electrospinning technology has attracted more attention as one of the most convenient and simple methods for preparing functional nanofibers and the related sutures. This review firstly discusses the structural classification of sutures and the performance analysis affecting the manufacture and use of sutures, followed by the discussion and classification of electrospinning technology, and then summarizes the relevant research on absorbable and non-absorbable sutures. Finally, several common polymers and biologically active substances used in creating sutures are concluded, the related applications of sutures are discussed, and the future prospects of electrospinning sutures are suggested.

Personalized and Defect-Specific Antibiotic-Laden Scaffolds for Periodontal Infection Ablation

Periodontitis compromises the integrity and function of tooth-supporting structures. Although therapeutic approaches have been offered, predictable regeneration of periodontal tissues remains intangible, particularly in anatomically complex defects. In this work, personalized and defect-specific antibiotic-laden polymeric scaffolds containing metronidazole (MET), tetracycline (TCH), or their combination (MET/TCH) were created via electrospinning. An initial screening of the synthesized fibers comprising chemo-morphological analyses, cytocompatibility assessment, and antimicrobial validation against periodontopathogens was accomplished to determine the cell-friendly and anti-infective nature of the scaffolds. According to the cytocompatibility and antimicrobial data, the 1:3 MET/TCH formulation was used to obtain three-dimensional defect-specific scaffolds to treat periodontally compromised three-wall osseous defects in rats. Inflammatory cell response and new bone formation were assessed by histology. Micro-computerized tomography was performed to assess bone loss in the furcation area at 2 and 6 weeks post implantation. Chemo-morphological and cell compatibility analyses confirmed the synthesis of cytocompatible antibiotic-laden fibers with antimicrobial action. Importantly, the 1:3 MET/TCH defect-specific scaffolds led to increased new bone formation, lower bone loss, and reduced inflammatory response when compared to antibiotic-free scaffolds. Altogether, our results suggest that the fabrication of defect-specific antibiotic-laden scaffolds holds great potential toward the development of personalized (i.e., patient-specific medication) scaffolds to ablate infection while affording regenerative properties.

In Vivo Versus In Vitro Degradation of a 3D Printed Resorbable Device for Ligation of Vascular Tissue in Horses

A resorbable 3D printed polydioxanone (PDO) device is manufactured to facilitate ligation of vascular tissue during surgery. The device must provide sufficient mechanical performance throughout the healing period. Therefore, degradation and mechanical performance of the device are investigated as a function of in vivo and in vitro aging. During aging the PDO device released cyclic and linear water-soluble products. In vivo aging resulted in higher relative number of linear oligomers in comparison to in vitro aging. A major loss of mechanical performance is observed after only 10 days in vivo and the Young's modulus (E) and tensile strength at break (σ_b ) decreased by 28% and 54%, respectively. This is in contrast to in vitro aging, where no loss of mechanical properties is observed during the same period. The in vivo aged devices exhibit clear holes in the matrices after 28 days, while apparent cracks are observed first after 140 days in vitro. These results highlight the sensitivity of the degradation process of resorbable devices with regards to the interactions of the device with the surrounding environment (tissues) and demonstrate the importance of in vivo testing as compliment to in vitro testing before clinical use of devices.

Novel Poly(ester urethane urea)/Polydioxanone Blends: Electrospun Fibrous Meshes and Films

In this work, we report the electrospinning and mechano-morphological characterizations of scaffolds based on blends of a novel poly(ester urethane urea) (PHH) and poly(dioxanone) (PDO). At the optimized electrospinning conditions, PHH, PDO and blend PHH/PDO in Hexafluroisopropanol (HFIP) solution yielded bead-free non-woven random nanofibers with high porosity and diameter in the range of hundreds of nanometers. The structural, morphological, and biomechanical properties were investigated using Differential Scanning Calorimetry, Scanning Electron Microscopy, Atomic Force Microscopy, and tensile tests. The blended scaffold showed an elastic modulus (~5 MPa) with a combination of the ultimate tensile strength (2 ± 0.5 MPa), and maximum elongation (150% ± 44%) in hydrated conditions, which are comparable to the materials currently being used for soft tissue applications such as skin, native arteries, and cardiac muscles applications. This demonstrates the feasibility of an electrospun PHH/PDO blend for cardiac patches or vascular graft applications that mimic the nanoscale structure and mechanical properties of native tissue.

Advances in carbohydrate-based polymers for the design of suture materials: A review

Suture materials constitute one of the largest biomedical material groups with a huge global market of $ 1.3 billion annually and employment in over 12 million procedures per year. Suture materials have radically evolved over the years, from basic strips of linen to more advanced synthetic polymer sutures. Yet, the journey to the ideal suture material is far from over and we now stand on the brink of a new era of improved suture materials with greater safety and efficacy. This next step in the evolutionary timeline of suture materials, involves the use of natural, carbohydrate polymers that have, until recent years, never before been considered for suture material applications. This review exposes the latest and most important advancements in suture material development while digging deep into how natural, carbohydrate polymers can serve to advance this field.

Biological compatibility, thermal and in vitro simulated degradation for poly(p-dioxanone)/poly(lactide-co-glycolide)/poly(ethylene succinate-co-glycolide)

Bio-absorbable polymers are widely desired to be applied and used as biomaterials for surgery hemostatic and medical tissue engineering devices. Ring-opening copolymerization reaction was applied to synthesize poly(ethylene succinate-co-glycolide) (PES-b-PGA). Stannous octoate was used as a catalyst whereas poly(ethylene succinate) was used as a macro-initiator to react with glycolide. PES-b-PGA was then used as a compatibilizer to prepare the blend biomaterial of PPDO/PLGA/PES-b-PGA by melt blending poly(p-dioxanone) (PPDO) with poly(lactide-co-glycolide) (PLGA). This would enhance the interactions of the inter-molecular chains and intra-molecular segments thus improving the compatibility. To obtain the biomaterial of PPDO/PLGA/PES-b-PGA with a regulated and controlled degradation and/or hydrolysis period, various ratios of PPDO, PLGA, and PES-b-PGA was blended. Behaviors of the thermal and in vitro simulated degradation, biological compatibility, cytotoxicity and subcutaneous implantation of PPDO/PLGA/PES-b-PGA were investigated. The results show that the in vitro hydrolytic degradation cycle is consistent with the wound healing time and that the biomaterial has slight cytotoxicity and it will do good to the cell proliferation, with 1 grade of cytotoxicity and the relative growth rate being the range from 92.5% to 96.2%. The implantation of the biomaterial into the rabbits' ears will not adversely affect the wound healing and the tissues surrounding the implanted sites. Therefore, the biomaterial has good biocompatibility and potential applications in medical tissue engineering devices.

Engineering and polymeric composition of drug-eluting suture: A review

Sutures are the most popular surgical implants in the global surgical equipment market. They are used for holding tissues together to achieve wound closure. However, controlling the body's immune response to these "foreign bodies" at site of infection is challenging. Natural polymers such as collagen, silk, nylon, and cotton, and synthetic polymers such as polycaprolactone, poly(lactic-co-glycolic acid), poly(p-dioxanone) and so forth, contribute the robust foundation for the engineering of drug-eluting sutures. The incorporation of active pharmaceutical ingredients (APIs) with polymeric composition of suture materials is an efficient way to reduce inflammatory reaction in the wound site as well as to control bacterial growth, while allowing wound healing. The incorporation of polymeric composition in surgical sutures has been found to add high flexibility as well as excellent physical and mechanical properties. Fabrication processes and polymer materials allow control over drug-eluting profiles to effectively address wound healing requirements. This review outlines and discusses (a) polymer materials and APIs used in suture applications, including absorbable and nonabsorbable sutures; (b) suture structures, such as monofilament, multifilament, barded and smart sutures; and (c) the existing manufacturing techniques for drug-eluting suture production, including electrospinning, melt-extrusion and coating.

Influence of several biodegradable components added to pure and nanosilver-doped PMMA bone cements on its biological and mechanical properties

Acrylic bone cements (BC) are wildly used in medicine. Despite favorable mechanical properties, processability and inject capability, BC lack bioactivity. To overcome this, we investigated the effects of selected biodegradable additives to create a partially-degradable BC and also we evaluated its combination with nanosilver (AgNp). We hypothesized that using above strategies it would be possible to obtain bioactive BC. The Cemex was used as the base material, modified at 2.5, 5 or 10 wt% with either cellulose, chitosan, magnesium, polydioxanone or tricalcium-phosphate. The resulted modified BC was examined for surface morphology, wettability, porosity, mechanical and nanomechanical properties and cytocompatibility. The composite BC doped with AgNp was also examined for its release and antibacterial properties. The results showed that it is possible to create modified cement and all studied modifiers increased its porosity. Applying the additives slightly decreased BC wettability and mechanical properties, but the positive effect of the additives was observed in nanomechanical research. The relatively poor cytocompatibility of modified BC was attributed to the unreacted monomer release, except for polydioxanone modification which increased cells viability. Furthermore, all additives facilitated AgNp release and increased BC antibacterial effectiveness. Our present studies suggest the optimal content of biodegradable component for BC is 5 wt%. At this content, an improvement in BC porosity is achieved without significant deterioration of BC physical and mechanical properties. Polydioxanone and cellulose seem to be the most promising additives that improve porosity and antibacterial properties of antibiotic or nanosilver-loaded BC. Partially-degradable BC may be a good strategy to improve their antibacterial effectiveness, but some caution is still required regarding their cytocompatibility. STATEMENT OF SIGNIFICANCE: The lack of bone cement bioactivity is the main limitation of its effectiveness in medicine. To overcome this, we have created composite cements with partially-degradable properties. We also modified these cements with nanosilver to provide antibacterial properties. We examined five various additives at three different contents to modify a selected bone cement. Our results broaden the knowledge about potential modifiers and properties of composite cements. We selected the optimal content and the most promising additives, and showed that the combination of these additives with nanosilver would increase cements` antibacterial effectiveness. Such modified cements may be a new solution for medical applications.

A novel braided biodegradable stent for use in congenital heart disease: Short-term results in porcine iliac artery

To evaluate the properties and efficacy of a novel braided biodegradable stent (BBS) consisting of poly (p-dioxanone) (PPDO) and polycaprolactone (PCL) for usage in children with congenital cardiovascular diseases. PCL/PPDO composite filaments were fabricated by coating PCL layers onto PPDO filaments, which were fused with PPDO monofilaments to form the BBS. Physical properties of BBSs including elastic recovery rate, deformation rate, and mechanical characteristics with adjunctive post-dilation were evaluated by radial force-tests. Ten BBS stents and 10 metallic wall stents (WS) as controls were implanted into the common carotid arteries of 10 pigs and angiography as well as histological examinations were performed 4 and 8 weeks after implantation. An 8 mm BBS with adjunctive post-dilation had the best morphological retention and dimension stability being similar to an 8 mm WS. Luminal gain percentages of BBS and WS immediately, 4 weeks and 8 weeks after implantation were 20.44 ± 2.82% and 27.08 ± 0.88%, 12.34 ± 0.18% and 17.32 ± 8.24%, as well as -1.76 ± 2.45% and - 0.98 ± 3.23%. Luminal areas, internal elastic laminas, neointimal areas, neointimal thicknesses, and area stenosis were not significantly different at 4 weeks and 8 weeks after implantation. Injury and inflammation were similar in both groups and no malposition, thrombosis or dissection occurred. BBS with adjunctive post-dilation showed good physical properties and mechanical stability noninferior to WS. In vivo evaluations showed that a BBS with post-ballooning had similar short-term outcomes as a WS. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1667-1677, 2019.

Biocompatibility and biodegradation properties of polycaprolactone/polydioxanone composite scaffolds prepared by blend or co-electrospinning

Electrospun polymer scaffolds are regarded as an ideal tissue engineering scaffold due to similar morphological properties with the native extracellular matrix. Among these, polycaprolactone is widely used to fabricate electrospun fibrous scaffolds due to its excellent biocompatibility, good mechanical properties, and ease of manufacture. However, its low biodegradation rate has a negative influence on its application in tissue engineering scaffold. To address this issue, this study prepared hybrid scaffolds composed of polycaprolactone and polydioxanone (a fast-degrading polyether-ester) via either the blend or co-electrospinning. Subsequently, the structural characteristics, mechanical strength, in vitro/vivo degradation, cellularization, and vascularization of two kinds of hybrid scaffolds were evaluated to decide which method is more suitable for producing tissue engineering scaffolds. The incorporation of polydioxanone increased the mechanical strength of both composite scaffolds. Moreover, co-electrospun scaffolds exhibited improved hydrophilicity compared to blend scaffolds. The results of in vitro and in vivo degradation studies showed that the degradation rate of both composite scaffolds was faster than that of neat polycaprolactone scaffolds due to the incorporated polydioxanone component. Especially in co-electrospun scaffolds, the fast degradation of polydioxanone fiber gave rise to larger pore size, thus leading to faster cellularization and better vascularization compared to blend scaffolds. Therefore, co-electrospinning was demonstrated to be superior to blend electrospinning for the preparation of composite scaffolds. Co-electrospun polycaprolactone–polydioxanone scaffolds may be promising candidates for tissue engineering.

Prevention of bacterial colonization on non-thermal atmospheric plasma treated surgical sutures for control and prevention of surgical site infections

Surgical site infections have a remarkable impact on morbidity, extended hospitalization and mortality. Sutures strongly contribute to development of surgical site infections as they are considered foreign material in the human body. Sutures serve as excellent surfaces for microbial adherence and subsequent colonization, biofilm formation and infection on the site of a surgery. Various antimicrobial sutures have been developed to prevent suture-mediated surgical site infection. However, depending on the site of surgery, antimicrobial sutures may remain ineffective, and antimicrobial agents on them might have drawbacks. Plasma, defined as the fourth state of matter, composed of ionized gas, reactive oxygen and nitrogen species, free radical and neutrals, draws attention for the control and prevention of hospital-acquired infections due to its excellent antimicrobial activities. In the present study, the efficacy of non-thermal atmospheric plasma treatment for prevention of surgical site infections was investigated. First, contaminated poly (glycolic-co-lactic acid), polyglycolic acid, polydioxanone and poly (glycolic acid-co-caprolactone) sutures were treated with non-thermal atmospheric plasma to eradicate contaminating bacteria like Staphylococcus aureus and Escherichia coli. Moreover, sutures were pre-treated with non-thermal atmospheric plasma and then exposed to S. aureus and E. coli. Our results revealed that non-thermal atmospheric plasma treatment effectively eradicates contaminating bacteria on sutures, and non-thermal atmospheric plasma pre-treatment effectively prevents bacterial colonization on sutures without altering their mechanical properties. Chemical characterization of sutures was performed with FT-IR and XPS and results showed that non-thermal atmospheric plasma treatment substantially increased the hydrophilicity of sutures which might be the primary mechanism for the prevention of bacterial colonization. In conclusion, plasma-treated sutures could be considered as novel alternative materials for the control and prevention of surgical site infections.

Small-diameter hybrid vascular grafts composed of polycaprolactone and polydioxanone fibers

Electrospun polycaprolactone (PCL) vascular grafts showed good mechanical properties and patency. However, the slow degradation of PCL limited vascular regeneration in the graft. Polydioxanone (PDS) is a biodegradable polymer with high mechanical strength and moderate degradation rate in vivo. In this study, a small-diameter hybrid vascular graft was prepared by co-electrospinning PCL and PDS fibers. The incorporation of PDS improves mechanical properties, hydrophilicity of the hybrid grafts compared to PCL grafts. The in vitro/vivo degradation assay showed that PDS fibers completely degraded within 12 weeks, which resulted in the increased pore size of PCL/PDS grafts. The healing characteristics of the hybrid grafts were evaluated by implantation in rat abdominal aorta replacement model for 1 and 3 months. Color Doppler ultrasound demonstrated PCL/PDS grafts had good patency, and did not show aneurysmal dilatation. Immunofluorescence staining showed the coverage of endothelial cells (ECs) was significantly enhanced in PCL/PDS grafts due to the improved surface hydrophilicity. The degradation of PDS fibers provided extra space, which facilitated vascular smooth muscle regeneration within PCL/PDS grafts. These results suggest that the hybrid PCL/PDS graft may be a promising candidate for the small-diameter vascular grafts.

Fabrication and feasibility study of an absorbable diacetyl chitin surgical suture for wound healing

Diacetyl chitin (DAC) is an acidylated chitin obtained using acetic anhydride mixed perchloric acid system. By wet spinning and weaving technique, DAC has been successfully developed into a novel absorbable surgical suture. Thanks to the unique properties of chitins, the potential application of this novel monocomponent multifilament DAC suture may break the monopoly of synthetic polymer sutures in wound closure area. In this study, DAC was synthesized and characterized by multiple approaches including elemental analysis, Fourier transform infrared spectrometry (FTIR), and X-ray diffraction (XRD). In addition, we performed the feasibility assessment of DAC suture (USP 2-0) as absorbable suture for wound healing. Several lines of evidences suggested that DAC suture had comparable mechanical properties as synthetic polymer sutures. Moreover, DAC suture retained approximately 63% of the original strength at 14 days and completely absorbed in 42 days with no remarkable tissue reaction in vivo. Most important of all, DAC suture significantly promoted skin regeneration with faster tissue reconstruction and higher wound breaking strength on a linear incisional wound model. All these results demonstrated the potential use of DAC suture in short- or middle-term wound healing, such as epithelial and connective tissue.

Poly(ester-ether)s: II. Properties of electrospun nanofibres from polydioxanone and poly(methyl dioxanone) blends and human fibroblast cellular proliferation

This article deals with an in-depth study of the thermal, mechanical and degradation behaviours of nanofibres from polydioxanone (PDX) and polydl-3-methyl-1,4-dioxan-2-one (PMeDX) and a comparison with their blend films. Varying ratios of both polymers were blended and electrospun from solution. Electrospun fibres exhibited a melting transition at 109 °C independently of the PMeDX content, which corresponds to the melting of PDX nanofibres. As a result of the drawing process, PMeDX had a reduced plasticizing effect on PDX. In general, it was observed that overall crystallinity of the fibres decreased from 53% to 36% with increasing PMeDX content and this impacted on their mechanical properties. The Young's moduli decreased as the PMeDX content of the fibres increased. However, an increase in strain at break and peak stress was noted as a result of a decrease in the fibre diameter. AFM images of the electrospun fibres showed an increasing degree of morphological heterogeneity with increasing PMeDX content. Thermal degradation studies showed that electrospun mats were thermally more stable than blend films, as confirmed by a two-fold increase in activation energy. The hydrolytic degradation of the electrospun mats conducted in phosphate buffer solution at 37 °C showed that the degradation followed a surface erosion mechanism as opposed to bulk degradation observed for blend films. Degradation of fibres was found to be mainly dependent on their diameter. On the other hand, the degradation of blend films depended on the overall crystallinity of the blends. Electrospun PDX/PMeDX nanofibrous scaffolds were also subjected to cell viability studies with human dermal fibroblasts, in which they did not show illicit response and demonstrated excellent cell attachment and proliferation.

Animal experimental study of the fully biodegradable atrial septal defect (ASD) occluder

This study was conducted to evaluate the feasibility, safety, biocompatibility, and degradation features of a fully biodegradable occluder for closure of atrial septal defect (ASD) in an acute canine model. The ASD was created in 20 healthy mongrel dogs by the brockenbrough needle, and the fully biodegradable occluders were implanted by self-made delivery system. The success rate and complications were observed. Acute ASD models were successfully created in 18 dogs, and 16 occluders were successfully implanted in the ASD models. Animals were sacrificed at different times after procedure. The cardiac gross anatomy showed that all occluders were stable in the interatrial septum, no vegetation or thrombus formation was observed on the surface of all occluders. They were embedded into endogenous host tissue gradually at 12-week follow-up. Different periods of pathological observations suggested that the occluders degraded gradually over about 24 weeks and essentially became an integral part of the septum. Transcatheter closure of ASD in acute canine model using the fully biodegradable ASD occluder has the potential of a high successful rate of technique, excellent biocompatibility, and fewer complications with adequate, immediate, and short-term results.

Long-term effect of gamma irradiation on the functional properties and cytocompatibility of multiblock co-polymer films

The purpose of this work was to investigate the long-term effect of gamma-irradiation treatment on the functional properties of PEG-PDLLA and PEG-PLGA films and to evaluate the cytocompatibility of sterilized samples. Chemical and thermal properties, and cytocompatibility of sterilized films were detected for samples at time zero and after storage at 5 ± 3°C for 60 days. An in vitro degradation study was carried out on polymer samples to examine the effect of sterilization on the degradation performances of co-polymer films. Incubated samples were characterized in terms of film surface structure (SEM), chemical (GPC) and thermal (DSC) properties. The study performed on films upon gamma sterilization showed no significant changes of the PEG-PDLLA and PEG-PLGA film structure, while GPC analysis highlighted that the effect of gamma irradiation was dependent on the Mw and composition of polymers. DSC traces suggested more pronounced gamma-ray effects on the PEG-PLGA multiblock co-polymer. During the stability study important changes in terms of structure surface, thermal properties and cytocompatibility were observed and investigated. Data collected during the in vitro degradation study emphasized the need to know and investigate the degradation performances and behaviour of polymer or polymer systems (as DDS, scaffolds and bandage) treated with gamma rays.

Review Paper: Absorbable Polymeric Surgical Sutures: Chemistry, Production, Properties, Biodegradability, and Performance

Among biomaterials used as implants in human body, sutures constitute the largest groups of materials having a huge market exceeding $1.3 billion annually. Sutures are the most widely used materials in wound closure and have been in use for many centuries. With the development of the synthetic absorbable polymer, poly(glycolic acid) (PGA) in the early 1970s, a new chapter has opened on absorbable polymeric sutures that got unprecedented commercial successes. Although several comparative evaluations of suture materials have been published, there were no serious attempts of late on a comprehensive review of production, properties, biodegradability, and performance of suture materials. This review proposes to bring to focus scattered data on chemistry, properties, biodegradability, and performance of absorbable polymeric sutures.

A biomimetic tubular scaffold with spatially designed nanofibers of protein/PDS bio-blends

Electrospun tubular conduit (4 mm inner diameter) based on blends of polydioxanone (PDS II(R)) and proteins such as gelatin and elastin having a spatially designed trilayer structure was prepared for arterial scaffolds. SEM analysis of scaffolds showed random nanofibrous morphology and well-interconnected pore network. Due to protein blending, the fiber diameter was reduced from 800-950 nm range to 300-500 nm range. Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) results confirmed the blended composition and crystallinity of fibers. Pure PDS scaffold under hydrated state exhibited a tensile strength of 5.61 +/- 0.42 MPa and a modulus of 17.11 +/- 1.13 MPa with a failure strain of 216.7 +/- 13%. The blending of PDS with elastin and gelatin has decreased the tensile properties. A trilayer tubular scaffold was fabricated by sequential electrospinning of blends of elastin/gelatin, PDS/elastin/gelatin, and PDS/gelatin (EG/PEG/PG) to mimic the complex matrix structure of native arteries. Under hydrated state, the trilayer conduit exhibited tensile properties (tensile strength of 1.77 +/- 0.2 MPa and elastic modulus of 5.74 +/- 3 MPa with a failure strain of 75.08 +/- 10%) comparable to those of native arteries. In vitro degradation studies for up to 30 days showed about 40% mass loss and increase in crystallinity due to the removal of proteins and "cleavage-induced crystallization" of PDS.