Composite Patch Research Articles

Adhesive Composite Hydrogel Patch for Sustained Transdermal Drug Delivery To Treat Atopic Dermatitis

Atopic dermatitis (AD) is a common chronic inflammatory skin disease. Continuous administration of steroids often causes undesired side effects; hence, drug delivery systems with high loading capacities and sustained release profiles are required. Herein, adhesive hydrogels for sustained transdermal delivery of dexamethasone (DEX), a potent corticosteroid, have been suggested for AD treatment. The adhesive composite hydrogels comprise a double network of polyacrylamide (PAM) and polydopamine (PDA) embedded with extra-large-pore mesoporous silica nanoparticles (XL-MSNs). The intrinsic skin adhesiveness of the dopamine-derived PAM/PDA hydrogels is further enhanced by XL-MSN incorporation that contributes to the simultaneous enhancement of cohesion and adhesion of the hydrogel. The resulting adhesive hydrogels exhibit a high water content and strong adhesion to porcine skin. A sustained release of DEX is obtained when DEX is loaded within the pores of XL-MSNs in PAM/PDA hydrogels compared to the rapid release from the direct loading of DEX in hydrogels. Application of DEX-loaded MSN@PAM/PDA hydrogels on an AD mouse model led to the significant suppression of AD symptoms, including the restoration of the thickened epidermal layer, decrease in inflammatory cell infiltration in the skin, recovery of collagen deposition, and decreased levels of immunoglobulin E. XL-MSN-embedded adhesive hydrogels could be a potential platform for topical drug delivery to treat inflammatory skin diseases.

Patch Repair Analysis of Impact Damaged Glass Fiber / Epoxy Composite Tubes Operating Under Internal Pressure

Application of composite patches is a useful technique to repair damaged structures such as wind turbines, air vehicles, pressure tanks because of lightweight, flexible design, and low price, and have found a widespread application area in many more industries. To avoid excessive weight of the repaired region as well as unnecessary material consumption composite patches need to be optimized according to shape, size and material specifications. This paper introduces a numerical assessment of size and material effect in composite-to-composite patches having specific shape and material properties. Adhesively bonded round-tipped composite patch pieces are utilized to repair a quadrilateral puncture damaged cylindrical thin-walled hollow composite tubes loaded by internal pressure. Glass fiber / epoxy patches with five different kinds of stacking sequence and ten different sizes are numerically investigated to achieve the best composite patch solutions. Although the safety factor of repaired tubes enhances by increasing tip radiuses and hence their sticking area, it is found to be not sufficient to ensure that the patching process is completely safe because of the fiber orientation playing an important role on the factor of safety. The patches having [0˚]4, [0˚, -45˚,45˚,90˚], and [0 ˚,90 ˚]2 stacking sequences and having adequate patch areas are found to be able to provide the safety value of “1.15” which is defined for normal safety class and below 5% coefficients of variation (COV) value in DNV’s Offshore Standard (DNV-OS-C501).

Experimental Investigation of Repair of Plate with Edge and Center Crack by Surface Bounded Composite Patch

Experimental Investigation of Repair of Plate with Edge and Center Crack by Surface Bounded Composite Patch

Selection of materials for repairing punctures of metal skin of semi-monocoque structures using composite patches

For repairing punctures of skin of semi-monocoque structures under field conditions, simple methods are sought to guarantee the reliability of the repaired structure. Therefore, adhesive joints and composite materials are being increasingly used in repairs. During repairs using adhesion, an important aspect that affects the quality of the joint is the selection of the adhesive and the quality of surface preparation of the parts to be joined. This is necessary to get the right bond strength and durability of the joint in working environments characterized by extreme temperatures and exposure to chemicals and moisture. The purpose of the study was to select an adhesive with good strength properties for bonding AW2024T3 aluminum sheets to carbon and glass composites, and to analyze the effect of metal surface preparation on the strength of adhesive joints (grinding, sandblasting and chemical surface preparation). The tests were carried out on overlap (metal-composite) specimens. For selected adhesives, strength tests were also carried out on specimens replicating the repaired damage with a diameter of 20 mm of metal skin repaired by different methods, including composite patches and adhesive joints. The specimens were loaded in tension and loss of stability. The tests made it possible to determine the requirements for composite patches used for repairing upper and lower airframe wing skins.

Analysis of the effect of localized corrosion shape on a cracked and notched 2024 AL plate repaired with composite patch under thermo-mechanical loading

This study highlights the analysis of corrosion shape effects under thermo-mechanical loading on the development of damage in corroded and cracked aluminum plates. This study is divided into two parts, the numerical analytical part, was performed to compare the effect of the corrosion geometry on the repair and adhesive damage; We analyzed the effects of damaged areas on the level of corrosion in the adhesive layer of three composite materials (boron/epoxy, glass/epoxy, and graphite/epoxy), and studied the change of the stress intensity factor for circle or square-shaped corrosion. The second part related to an experimental study of the corrosion shape on the ultimate strength of the damaged plate repaired by the boron/epoxy composite material. The results obtained, indicated that the effect of the circular shape of corrosion is small compared to the square shape. The type of composite material (boron / epoxy) has proven its optimal effect on repair.

Effect of the Fibers Orientation of the Different Types of Composite Plates Notched of U-Shape Repaired by Composite Patch

The main objective of this work is to repair a structure of composite materials by gluing composite patches with different fiber directions. The effects of stress distribution, damaged area ratio, stress intensity factor KIC and imposed stacking sequence were highlighted by a comprehensive study that contained two sides, an applied experimental side and a numerical model side. The composite materials plates studied in this work are 8-layer of graphite/epoxy, glass/epoxy and boron/epoxy, with different angles. The results obtained clearly show with respect to the experimental side that the orientation of the fibers affects the ultimate strength of failure and that the fibers oriented longitudinally in the direction of the tensile strength give us an ideal performance of the composite material. As for the model aspect of this study, the effects of stress intensity factor and the relationship between the damaged area and the fiber orientation on the performance of these patches were studied. We can conclude from this study that the orientation of the fibers has an important role in the performance of the composite material and its efficiency in repair.

Intraperitoneal onlay mesh versus laparoscopy-assisted ventral hernia patch mesh repair in small primary ventral hernias

Aims: The aim of this study is to compare and evaluate short-term outcomes of laparoscopy-assisted composite patch mesh repair versus laparoscopic intraperitoneal onlay mesh in small primary midline ventral hernias. Materials and Methods: Eighty consecutive patients with small (<2 cm) midline ventral hernia admitted to the Department of General and Laparoscopic surgery at Sir Ganga Ram Hospital, New Delhi, from January 2017 to May 2019 were included in the study and randomised into two groups. Group A included patients who underwent laparoscopic intraperitoneal onlay mesh repair with the classical barrier flat mesh and Group B patients underwent laparoscopy-assisted ventral hernia patch-mesh repair. Parameters assessed at the follow-up were early post-operative pain by Visual Analogue Scale score, wound complications, early recurrence and hospital stay. Results: Early post-operative pain was more in the laparoscopic intraperitoneal onlay mesh group and the difference was statistically significant. Usage of additional analgesia in the post-operative period was required only in the laparoscopic intraperitoneal onlay mesh group. There was a statistically significant difference between the two groups in terms of hospital stay. Conclusion: For primary midline ventral hernia, with defect size <2 cm, laparoscopy-assisted composite patch mesh repair is feasible and safe. It causes less pain and necessitates less usage of additional analgesia enabling patients to be discharged earlier.

Multifunctional microneedle patches with aligned carbon nanotube sheet basement for promoting wound healing

Wound healing has become a health concern and economic burden worldwide for its high incidence and complexity. Attempts to improve wound treatment tend to develop biomedical patches with delicate structure design and functionality. In this paper, we present novel multifunctional microneedle patches with aligned carbon nanotube (CNT) sheet basement for promoting wound healing. Because of the outstanding biocompatibility, biodegradability and non-immunogenicity, hyaluronic acid (HA) is utilized to construct the CNT-integrated microneedle patch with vascular endothelial growth factor (VEGF) encapsulation. It was found that the aligned CNT layer basement could not only impart the composite microneedle patch with orientation morphology, but also endow the patch with controllable release performance, due to its photo-thermal or electro-thermal conversion capacity. Based on these features, we have demonstrated that the highly ordered microstructure of CNT could effectively induce the orientation of fibroblasts; while VEGF release could facilitate tubular formation of endothelial cells. Thus, the aligned CNT and VEGF-loaded multifunctional patch is beneficial to the wound repair process in a typical animal experiment. These results indicate that the proposed microneedle patch is potentially promising for regeneration medicine.

Enhanced intradermal delivery of Dragon's blood in biocompatible nanosuspensions hydrogel patch for skin photoprotective effect.

Dragon's Blood is a member of the Chinese medicinal herb, having anti-oxygen and anti-inflammatory activity for the photoprotective effect. However, the poor water solubility of raw Dragon's Blood powder has limited its intradermal delivery process. In this study, we evaluated nanosuspensions to enhance intradermal delivery of Dragon's Blood exerting a photoprotective effect. The prepared nanosuspension was added to a composite hydrogel patch matrix for better skin application. In the present research, we used biocompatible materials hyaluronic acid and amino acid surfactants as nanosuspension stabilizers and agar/gelatin/sodium polyacrylate as hydrogel patch matrix. The prepared Dragon's Blood nanosuspension had a particle size of 447.0 ± 48.6nm. The micro-structures morphology and viscoelasticity characteristics by SEM and rheological testing confirmed a sufficient crosslinked hydrogel network. The skin retention amount of Dragon's Blood nanosuspension was 1.48 times of raw Dragon's Blood powder water suspension, and the skin penetration amount of Dragon's Blood nanosuspension was only about 1/3 of Dragon's Blood DMSO solution. In the UVB-irradiated HaCaT cell phototoxicity model, Dragon's Blood nanosuspension also significantly increased cell viability by about 1 time of the model group and decreased the production of reactive oxygen species about 1/2 times of model group. In vivo safety and efficiency evaluation experiment illustrated that DB-NS hydrogel patch processes have favorable safety and photoprotective effect with no skin irritancy and phototoxicity. Furthermore, DB-NS and DB-NS hydrogel patches could protect skin from UVA and UVB irritating skin reactions. Overall, our study of the combined use of biocompatible and biodegradable materials as excipients of nanosuspension and hydrogel patch could be used as an effective additive of Intradermal delivery and skin photoprotection.

Reliability-based design considering prediction interval estimation to optimize composite patches

A modified reliability-based design optimization (RBDO) technique was developed and applied to optimal designs of composite patches of a perforated base plate. The modified RBDO technique uses adaptive sampling strategies for the response surface method (RSM) to enhance the computational efficiency of the traditional RSM-based RBDO technique. Optimal design of composite patches was conducted for a perforated base plate using the newly proposed failure criteria which state that two conditions must be satisfied simultaneously for failure to occur. One condition is based on stress magnitude while the second condition is associated with the stress gradient. In other words, the failure criteria suggests that failure is more likely for higher stresses and lower stress gradients. Therefore, the design optimization of the composite patch was conducted to decrease the stress and to increase the stress gradient simultaneously at the edge of the perforated hole of the base plate in order to optimize the probability of failure of the base plate with composite patches.

Structural Color Ionic Hydrogel Patches for Wound Management.

Ionic hydrogels have attracted extensive attention because of their wide applicability in electronic skins, biosensors, and other biomedical areas. Tremendous effort is dedicated to developing ionic hydrogels with improved detection accuracy and multifunctionality. Herein, we present an inverse opal scaffold-based structural color ionic hydrogel with the desired features as intelligent patches for wound management. The patches were composed of a polyacrylamide-poly(vinyl alcohol)-polyethylenimine-lithium chloride (PAM-PVA-PEI-LiCl) inverse opal scaffold and a vascular endothelial growth factor (VEGF) mixed methacrylated gelatin (GelMA) hydrogel filler surface. The scaffold imparted the composite patches with brilliant structural color, conductive property, and freezing resistance, while the VEGF-GelMA surface could not only prevent the ionic hydrogel from the interference of complex wound conditions but also contribute to the cell proliferation and tissue repair in the wounds. Thus, the hydrogel patches could serve as electronic skins for in vivo wound healing and monitoring with high accuracy and reliability. These features indicate that the proposed structural color ionic hydrogel patches have great potential for clinical applications.

Progressive failure analysis of U-notched thin composite plates repaired with a double-sided composite patch

In this study, carbon fiber-reinforced U-notched composite plates were repaired with composite patches made of the same material using adhesive bonding and their mechanical performance was investigated experimentally and numerically. Repairs were made by applying a double-sided composite patch to the notched thin composite plates. The repaired composite plates were tested under tensile load. The effect of the variation in notch width and depth on the repaired plate failure load and type was investigated. At the end of the experiments, load–displacement graphs of each specimen were obtained. The effect of variation in notch depth and width in the repaired specimens was not as dominant as in the non-repaired specimens. While the variation in notch dimensions changed the failure load between 34% and 37% in the non-repaired specimens, this rate was between 18% and 21% in the repaired specimens. In the numerical analysis, progressive failure analysis was performed using the Hashin Failure Criteria. Subroutine codes were written in the program Ansys, which uses the finite element method for numerical analysis. In the results, numerical and experimental load–displacement graphs and failure types of the specimens are presented comparatively. The convergence rate of the experimental and numerical data was between 92% and 99.8%.

Effect of Impact Position on Repaired Composite Laminates Subjected to Multi-Impacts.

Because the certification of aircraft structures requires significant costs and time-consuming experimental tests, all the studies carried out are strong contributions to the applicability of repairs based on adhesively bonded fibre composite patches. In this context, the main goal of this study aims to analyse the effect of the impact position on the multi-impact response of repaired composites. The results will be compared with those obtained in composites containing holes. Therefore, experimental tests will be carried out using an energy of 8 J and centrally supported samples. It was noted that the patch region proved to be very sensitive to impact due to its thickness. Full perforation occurred after two to three impacts, and to obtain higher strength it would be necessary to increase the thickness of the patch. However, depending on the location of the repair, this could bring aerodynamic problems. For the distance of 15 mm from the centre, an overlap region, the repaired laminate shows 494.7% higher impact strength than a laminate with a hole. In this case, the effect of the stress concentration is determinant in the impact fatigue life. Finally, for the 35 mm distances that are close to the border, no significant changes in impact fatigue life were observed for both the repaired laminates and those containing the hole. This leads to the conclusion that the border effect is much more significant than the presence of the hole for this distance.

The Treatment of Keloid Scars via Modulating Heterogeneous Gelatin-Structured Composite Microneedles to Control Transdermal Dual-Drug Release.

Keloid scarring is an abnormal scar disease characterised by excessive proliferation of fibroblasts and over-deposition of collagen during wound healing. Although various treatments for keloid scars have been developed, preventive medicine is believed to be a promising strategy. The skin barrier limits the gentle topical administration of medicaments such as creams and hydrogel dressings, resulting in reduced therapeutic efficacy. In recent years, microneedles (MNs) have been regarded as an appreciable device for topical administration without inducing side effects, and they are painless and do not cause bleeding. In this study, an MN patch with controlled transdermal dual-drug release was developed to achieve combinatory treatment of keloid scars using a heterogeneous gelatin-structured composite MN. Gelatin hydrogel was used as a substrate to load gallic acid (GA) and quercetin-loaded amphiphilic gelatin nanoparticles to fabricate dual-drug heterogeneous composite MNs. The results of the insertion test and mechanical properties of the MNs showed that the heterogeneous composite MN patches could be self-pressed into the stratum corneum and control dual-drug release at different time periods. GA was released at an earlier stage to retard the proliferation of fibroblasts, and quercetin was released at a later stage as a strong antioxidant to erase the generation of reactive oxygen species. Furthermore, real-time quantitative polymerase chain reaction data indicated that the gene expression of fibroblasts (such as Col I and III) was downregulated in the dual-drug system. The above results demonstrate that using heterogeneous composite MNs with the combination of dual-drug pharmacology is beneficial for preventing keloid scar formation.

Fibrin-based cardiac patch containing neuregulin-1 for heart repair after myocardial infarction

Cardiac patch, a scaffold layered on the surface of the heart that can provide mechanical and regeneration support for damaged myocardium, has provided a promising solution to treat severe myocardial infarction (MI). In this work, a fibrin based cardiac patch loaded with neuregulin-1 (NRG-1) is developed to attach locally to the infract area of heart. The composite patch exhibited good biocompatibility and promoted cardiomyocyte proliferation in vitro via NRG-1/ErbB signaling. Moreover, implantation of this patch to the infracted border zone reduced cell apoptosis, promoted angiogenesis and inhibited fibrosis, which reduced infraction size and improved cardiac function consequently. Thus, the combination of natural biomaterial fibrin and bioactive factor NRG-1 might have a promising potential for clinical application of MI treatment.

Strength prediction of a steel pipe having a hemi-ellipsoidal corrosion defect repaired by GFRP composite patch using artificial neural network

Local stress concentration occurs when faults are present in pipelines under pressure. An example of such defects is the problem of corrosion caused by the environment in the field of pipeline installation. In the first part of this paper, we attempt to model the corrosion in the hemi-ellipsoidal form in order to study the locations of stress concentration in the specimens by several experimental cases and their influence on the stress resistance. The Gurson-Tvergaard-Needleman (GTN) mesoscopic damage model is used to simulate the specimens with good accuracy. In the second part, the investigation is extended to a pipe under static pressure with and without the presence of a glass fibre reinforced polymer (GFRP) composite patch. The maximum stress and percent stress reduction in a defected pipe with a hemi-ellipsoidal defect are determined using a 3D finite element model. This part examines the impact of the geometry of the composite patches on the percentage reduction of the maximum stresses in a section of pipeline subjected to static pressure. In the third part, the stresses and the percentage reduction in the maximum stresses are predicted using an artificial neural network (ANN). An inverse problem using ANN and Jaya algorithm is proposed to predict the group level of different sizes of defects under composite patches based on the maximum stress and percentage reduction of stress that the pipe withstands. The new method relates directly to real-world pipeline construction and repair applications. It could be also used for structural safety monitoring.

P-068 RESULTS OF THE OPEN INTRAPERITONEAL ONLAY MESH TECHNIQUE WITH A PREFORMED PATCH FOR PRIMARY VENTRAL HERNIA AND INCISIONAL HERNIA

Abstract Aim Primary ventral hernias and incisional hernias are frequent, but long–term results of their repair with a preformed patch are scarce. The aim was to evaluate the surgical results of the treatment of these hernias with the open intraperitoneal onlay mesh (open IPOM) technique, and to determine the needed follow–up for recurrence. Material and methods Observational retrospective single institution study of all consecutive patients intervened for ventral or incisional hernia with diameter inferior to 4 cm, from January 2013 to June 2020. The surgical repair was performed according to the open IPOM technique with a preformed patch and the defect was left unclosed. Relapsed hernias, those with a defect ≥ 4 cm, and lateral wall hernias were excluded. Results A total of 146 patients were intervened: 61.6% with umbilical hernias, 8.2% with epigastric hernias, 26.7% with trocar incisional hernias, and 3.4% with other incisional hernias. The global recurrence rate was 7.5% (11/146). Specifically, there it was 7.8% in umbilical hernias, 0% in epigastric hernias, 7.7% in trocar incisional hernias, and 20% (1/5) in other incisional hernias. The median time for recurrence was 14 months (IQR: 4,4–18,7). The median presential follow–up was 17,4 months (IQR: 6,5–27,3), and the median telematic follow-up was 36,9 months (IQR: 27,2–49,6). Conclusions The open IPOM technique with a preformed patch offers good results for the treatment of ventral and incisional hernias. A 2-year follow-up is still needed for the recurrence diagnosis. Note The preformed patch used was the Parietex™ Composite Ventral Patch (Medtronic, Minneapolis, MN, EEUU).

Antibacterial, adhesive, and MSC exosomes encapsulated microneedles with spatio-temporal variation functions for diabetic wound healing

Chronic wounds affect healthcare systems and increase the risk of infection. Despite the clinical demand for improving healing, an effective and safe therapeutic approach is still lacking. Here, we present a novel spatio-temporal-varying adhesive microneedle (MN) patch encapsulated with mesenchymal stem cell-derived exosomes (MSC-exos) and antibacterial Ag nanoparticles (AgNPs) for improving wound healing. This MN patch is fabricated by replicating a predesigned flexible template. Consisting of porous methacrylate gelatin hydrogels, the MN tips can continuously deliver anti-inflammatory and pro-angiogenic MSC-exos to wound beds, which can accelerate healing by improving cell functions, remodeling blood vessels and restoring immune systems. Besides, the silk-fibroin-composed MN back enables the patch to stick to the skin well and fix at the wounded site, thus avoiding secondary bandage. By incorporating AgNPs in the MN back, the MN patch is endowed with the ability to efficiently resist microbial contamination and further benefits wound repair. Such a composite MN patch performs well in relieving inflammation, promoting angiogenesis, and suppressing wound-infecting bacteria during wound injury in diabetic rats, with no adverse effects observed. All the features make this multifunctional MN patch potentially valuable for clinical applications.

XFEM–ANN approach to predict the fatigue performance of a composite patch repaired aluminium panel

A novel extended finite element method (XFEM)-artificial neural network (ANN) approach is proposed to predict the performance of aluminium panels repaired single-sided with a composite patch. The optimized deep neural network model developed using data sets generated from XFEM—benchmarked against experimental results—has the architecture of 4-17-17-2 and it predicts the stress intensity factor and fatigue life cycle with the maximum error of 0.15 % and 0.25 %, respectively. Global sensitivity analysis of the model is performed based on the Shapley values and it reveals that lamina orientation is the least influencing. A comparison of computational time reveals that 100 % reduction is achieved by using the optimized ANN model. The findings establish the use of ANN for aiding as well as accelerating the composite patch repair process for various engineering applications.

Stem cell laden nano and micro collagen/PLGA bimodal fibrous patches for myocardial regeneration

BackgroundAlthough the use of cardiac patches is still controversial, cardiac patch has the significance in the field of the tissue engineered cardiac regeneration because it overcomes several shortcomings of intra-myocardial injection by providing a template for cells to form a cohesive sheet. So far, fibrous scaffolds fabricated using electrospinning technique have been increasingly explored for preparation of cardiac patches. One of the problems with the use of electrospinning is that nanofibrous structures hardly allow the infiltration of cells for development of 3D tissue construct. In this respect, we have prepared novel bi-modal electrospun scaffolds as a feasible strategy to address the challenges in cardiac tissue engineering .MethodsNano/micro bimodal composite fibrous patch composed of collagen and poly (D, L-lactic-co-glycolic acid) (Col/PLGA) was fabricated using an independent nozzle control multi-electrospinning apparatus, and its feasibility as the stem cell laden cardiac patch was systemically investigated.ResultsNano/micro bimodal distributions of Col/PLGA patches without beaded fibers were obtained in the range of the 4-6% collagen concentration. The poor mechanical properties of collagen and the hydrophobic property of PLGA were improved by co-electrospinning. In vitro experiments using bone marrow-derived mesenchymal stem cells (BMSCs) revealed that Col/PLGA showed improved cyto-compatibility and proliferation capacity compared to PLGA, and their extent increased with increase in collagen content. The results of tracing nanoparticle-labeled as well as GFP transfected BMSCs strongly support that Col/PLGA possesses the long-term stem cells retention capability, thereby allowing stem cells to directly function as myocardial and vascular endothelial cells or to secrete the recovery factors, which in turn leads to improved heart function proved by histological and echocardiographic findings.ConclusionCol/PLGA bimodal cardiac patch could significantly attenuate cardiac remodeling and fully recover the cardiac function, as a consequence of their potent long term stem cell engraftment capability.