Highly Bioadhesive Polymer Membrane Continuously Releases Cytostatic and Anti-Inflammatory Drugs for Peritoneal Adhesion Prevention

A self-fused peptide-loaded hydrogel with injectability and tissue-adhesiveness for preventing postoperative peritoneal adhesions

Peritoneal adhesions commonly occur following abdominal or pelvic surgery and can cause serious complications. Currently, physical barriers are the primary approach used in clinical practice to prevent adhesion, although their effectiveness is frequently inadequate. In this study, we developed an injectable peptide-loaded hydrogel with multiple functions, including self-fusion, tissue-adhesiveness, anti-inflammation, anti-cell adhesion and anti-angiogenesis. To assess the effectiveness of these hydrogels, which are stabilized by dynamic imine bonds and acetal connections, in preventing postoperative abdominal adhesions, we utilized both a rat abdominal adhesion model and a rat model simulating repeated-injury adhesions. In comparison to the commercially available HA hydrogel, as-prepared hydrogels exhibited significant reductions in inflammation, fibrosis, and angiogenesis, leading to an obvious decrease in peritoneal adhesions. Moreover, this peptide-loaded hydrogel demonstrated an ideal degradation time, maintaining an in vivo viability for about 10 days. We believe this peptide-loaded hydrogel presents a promising solution for the challenging clinical issue of postoperative abdominal adhesions.

Advanced postoperative tissue antiadhesive membranes enabled with electrospun nanofibers

Tissue adhesion is one of the most common postoperative complications, which is frequently accompanied by inflammation, pain, and even dyskinesia, significantly reducing the quality of life of patients. Thus, to prevent the formation of tissue adhesions, various strategies have been explored. Among these methods, placing anti-adhesion membranes over the injured site to separate the wound from surrounding tissues is a simple and prominently favored method. Recently, electrospun nanofibers have been the most frequently investigated antiadhesive membranes due to their tunable porous structure and high porosities. They not only can act as an essential barrier and functional carrier system but also allow for high permeability and nutrient transport, showing great potential for preventing tissue adhesion. Herein, we provide a short review of the most recent applications of electrospun nanofibrous antiadhesive membranes in tendons, the abdominal cavity, dural sac, pericardium, and meninges. Firstly, each section highlights the most representative examples and they are sorted based on the latest progress of related research. Moreover, the design principles, preparation strategies, overall performances, and existing problems are highlighted and evaluated. Finally, the current challenges and several future ways to develop electrospun nanofibrous antiadhesive membranes are proposed. The systematic discussion and proposed directions can shed light on ideas and guide the reasonable design of electrospun nanofibrous membranes, contributing to the development of exceptional tissue anti-adhesive materials in the foreseeable future.

Chitosan-crosslinked polyvinyl alcohol anti-swelling hydrogel designed to prevent abdominal wall adhesion

Abdominal adhesion is a frequent clinical issue with a high incidence rate and consequences following intra-abdominal surgery. Although many anti-adhesion materials have been used in surgical procedures, additional research is still needed to determine which ones have the most robust wet tissue adhesion, the best anti-postoperative adhesion, and the best anti-inflammatory properties. We have developed an excellent tissue adhesion and anti-swelling polyvinyl alcohol-chitosan hydrogel (AS hydrogel). According to in vitro cell testing, AS hydrogel significantly decreased inflammation around cells and exhibited good biocompatibility. Further, we assessed how well AS hydrogel prevented intraperitoneal adhesion using a rabbit model with cecum and abdominal wall injuries. According to the data, AS hydrogel has excellent anti-inflammatory and biodegradability properties compared to the control group. It can also prevent intestinal and abdominal wall injuries from occurring during surgery. Based on these results, hydrogel appears to be a perfect new material to prevent postoperative abdominal wall adhesion.

Revolutionizing Brain Drug Delivery: Buccal Transferosomes on the Verge of a Breakthrough

The buccal cavity, also known as the oral cavity, is a complex anatomical structure that plays a crucial role in various physiological processes. It serves as a gateway to the digestive system and facilitates the initial stages of food digestion and absorption. However, its significance extends beyond mere digestion as it presents a promising route for drug delivery, particularly to the brain. Transferosomes are lipid-based vesicles that have gained significant attention in the field of drug delivery due to their unique structure and properties. These vesicles are composed of phospholipids that form bilayer structures capable of encapsulating both hydrophilic and lipophilic drugs. Strategies for the development of buccal transferosomes for brain delivery have emerged as promising avenues for pharmaceutical research. This review aims to explore the various approaches and challenges associated with harnessing the potential of buccal transferosomes as a means of enhancing drug delivery to the brain. By understanding the structure and function of both buccal tissue and transferosomes, researchers can develop effective formulation methods and characterization techniques to optimize drug delivery. Furthermore, strategic approaches and success stories in buccal transferosome development are highlighted, showcasing inspiring examples that demonstrate their potential to revolutionize brain delivery.

A Zwitterionic Hydrogel with Anti-Oxidative and Anti-Inflammatory Properties for the Prevention of Peritoneal Adhesion by Inhibiting Mesothelial-Mesenchymal Transition

Postoperative peritoneal adhesion is a serious clinical complication. Various hydrogel barriers have been developed to prevent peritoneal adhesion. However, it remains a challenge to design a hydrogel with desirable physicochemical properties and bioactivities. In this study, a zwitterionic polysaccharide-based multifunctional hydrogel is developed using epigallocatechin-3-gallate (EGCG) to prevent postoperative abdominal adhesion. This hydrogel is simple to use and has desirable properties, such as excellent injectability, self-healing, and non-swelling properties. The hydrogel also has ultralow fouling capabilities, such as superior bactericidal performance, cell and protein adhesion, and low immunogenicity resistance. Moreover, the hydrogel exhibits good antioxidant activity, which is attributed to the integration of EGCG. Furthermore, the detailed mechanism from in vivo and in vitro experimental studies illustrates that hydrogel compositions can synergistically prevent adhesion formation through multiple pathways, including anti-inflammatory and antioxidant capabilities and inhibition effects on the mesothelial-mesenchymal transition (MMT) process induced by transforming growth factor (TGF-β). In summary, this zwitterionic multifunctional hydrogel has great potential to prevent postoperative adhesion formation in the clinical setting.

Creation of Chitosan-Based Nanocapsule-in-Nanofiber Structures for Hydrophobic/Hydrophilic Drug Co-Delivery and Their Dressing Applications in Diabetic Wounds

Nanofiber meshes (NFMs) loaded with therapeutic agents are very often employed to treat hard-to-heal wounds such as diabetic wounds. However, most of the NFMs have limited capability to load multiple or hydrophilicity distinctive-therapeutic agents. The therapy strategy is therefore significantly hampered. To tackle the innate drawback associated with the drug loading versatility, a chitosan-based nanocapsule-in-nanofiber (NC-in-NF) structural NFM system is developed for simultaneous loading of hydrophobic and hydrophilic drugs. Oleic acid-modified chitosan is first converted into NCs by the developed mini-emulsion interfacial cross-linking procedure, followed by loading a hydrophobic anti-inflammatory agent Curcumin (Cur) into the NCs. Sequentially, the Cur-loaded NCs are successfully introduced into reductant-responsive maleoyl functional chitosan/polyvinyl alcohol NFMs containing a hydrophilic antibiotic Tetracycline hydrochloride. Having a co-loading capability for hydrophilicity distinctive agents, biocompatibility, and a controlled release property, the resulting NFMs have demonstrated the efficacy on promoting wound healing either in normal or diabetic rats.

An anti-inflammatory chondroitin sulfate-poly(lactic-co-glycolic acid) composite electrospinning membrane for postoperative abdominal adhesion prevention

Postoperative abdominal adhesion is a very common and serious complication, resulting in pain, intestinal obstruction and heavy economic burden. Post-injury inflammation that could activate the coagulation cascade and deposition of fibrin is a major cause of adhesion. Many physical barrier membranes are used to prevent abdominal adhesion, but their efficiency is limited due to the lack of anti-inflammatory activity. Here, an electrospinning membrane composed of poly(lactic-co-glycolic acid) (PLGA) providing support and mechanical strength and chondroitin sulfate (CS) conferring anti-inflammation activity is fabricated for preventing abdominal adhesion after injury. The PLGA/CS membrane shows a highly dense fiber network structure with improved hydrophilicity and good cytocompatibility. Importantly, the PLGA/CS membrane with a mass ratio of CS at 20% provides superior anti-adhesion efficiency over a native PLGA membrane and commercial poly(D, L-lactide) (PDLLA) film in abdominal adhesion trauma rat models. The mechanism is that the PLGA/CS membrane could alleviate the local inflammatory response as indicated by the promoted percentage of anti-inflammatory M2-type macrophages and decreased expression of pro-inflammatory factors, such as IL-1β, TNF-α and IL-6, resulting in the suppression of the coagulation system and the activation of the fibrinolytic system. Furthermore, the deposition of fibrin at the abdominal wall was inhibited, and the damaged abdominal tissue was repaired with the treatment of the PLGA/CS membrane. Collectively, the PLGA/CS electrospinning membrane is a promising drug-/cytokine-free anti-inflammatory barrier for post-surgery abdominal adhesion prevention and a bioactive composite for tissue regeneration.

Polymer nanomaterials for use as adjuvant surgical tools

Materials employed in the treatment of conditions encountered in surgical and clinical practice frequently face barriers in translation to application. Shortcomings can be generalized through their reduced mechanical stability, difficulty in handling, and inability to conform or adhere to complex tissue surfaces. To overcome an amalgam of challenges, research has sought the utilization of polymer-derived nanomaterials deposited in various fashions and formulations to improve the application and outcomes of surgical and clinical interventions. Clinically prevalent applications include topical wound dressings, tissue adhesives, surgical sealants, hemostats, and adhesion barriers, all of which have displayed the potential to act as superior alternatives to current materials used in surgical procedures. In this review, emphasis will be placed not only on applications, but also on various design strategies employed in fabrication. This review is designed to provide a broad and thought-provoking understanding of nanomaterials as adjuvant tools for the assisted treatment of pathologies prevalent in surgery. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Implantable Materials and Surgical Technologies > Nanoscale Tools and Techniques in Surgery.

Salt sensitive purely zwitterionic physical hydrogel for prevention of postoperative tissue adhesion

Abdominal adhesions are a class of serious complications following abdominal surgery, resulting in a complicated and severe syndrome and sometimes leading to a Gordian knot. Traditional therapies employ hydrogels synthesized using complicated chemical formulations-often with click chemistry or thermal responsive hydrogel. The complicated synthesis process and severe conditions limit the extent of the hydrogels' applications. In this work, poly 3-[2-(methacryloyloxy)ethyl](dimethyl)-ammonio]-1-propanesulfonate (PSBMA) polymer was synthesized to self-assemble into physical hydrogels due to the inter- and intramolecular ion interactions. The strong static interaction bonding density has a substantial impact on the gelation and physicochemical properties, which is beneficial to clinical applications and offers a novel way to obtain the desired hydrogel for a specific biomedical application. Intriguingly, this PSBMA polymer can be customized into a transient network with outstanding antifouling capability depending on the ion concentration. As ion concentration increases, the PSBMA hydrogel dissociated completely, endowing it as a candidate for adhesion prevention. In the cecum-sidewall model, the PSBMA hydrogel demonstrated superior anti-adhesion properties than commercial HA hydrogel. Furthermore, we have demonstrated that this PSBMA hydrogel could inhibit the inflammatory response and encourage anti-fibrosis resulting in adhesion prevention. Most surprisingly, the recovered skins of cecum and sidewall are as smooth as the control skin without any scar and damage. In conclusion, a practical hydrogel was synthesized using a facile method based on purely zwitterionic materials, and this ion-sensitive, antifouling adjustable supramolecular hydrogel with great clinic transform potential is a promising barrier for preventing postoperative tissue adhesion. STATEMENT OF SIGNIFICANCE: The development of hydrogels with satisfactory coverage, long retention time, facile synthetic method, and good biocompatibility is vital for preventing peritoneal adhesions. Herein, we developed a salt sensitive purely zwitterionic physical hydrogel poly 3-[2-(methacryloyloxy)ethyl](dimethyl)-ammonio]-1-propanesulfonate (PSBMA) hydrogel to effectively prevent postoperative and recurrent abdominal adhesions. The hydrogel was simple to synthesize and easy to use. In the cecum-sidewall model, PSBMA hydrogel could instantaneously adhere and fix on irregular surfaces and stay in the wound for more than 10 days. The PSBMA hydrogel could inhibit the inflammatory response, encourage anti-fibrosis, and restore smoothness to damaged surfaces resulting in adhesion prevention. Overall, the PSBMA hydrogel is a promising candidate for the next generation of anti-adhesion materials to meet clinical needs.

Polypropylene composite hernia mesh with anti-adhesion layer composed of PVA hydrogel and liposomes drug delivery system

Polypropylene (PP) mesh has been widely used in hernia repair as prosthesis material owing to its excellent balanced biocompatibility and mechanical properties. However, abdominal adhesion between the visceral and PP mesh is still a major problem. Therefore, anti-adhesive PP mesh was designed with poly(vinyl alcohol) (PVA) hydrogel and liposomes drug delivery system. First, PVA hydrogel coating was formed on the surface of PP mesh with freezing-thawing processing cycles (FTP). Subsequently, the lyophilized PVA₁₀-c-PP was immersed in rapamycin (RPM)-loaded liposome solution until swelling equilibrated to obtain the anti-adhesion mesh RPM@LPS/PVA₁₀-c-PP. It was demonstrated that the hydrogel coating can stably fix on the surface of PP mesh even after immersed in PBS solution at 37 °C or 40 °C for up to 30 days. In vitro cell tests revealed the excellent cytocompatibility and the potential to inhibit cell adhesion of the modified PP mesh. Moreover, the anti-adhesive effects of the RPM@LPS/PVA₁₀-c-PP mesh was evaluated through in vivo experiments. The RPM@LPS/PVA₁₀-c-PP mesh exhibited less adhesion than original PP mesh throughout the duration of implantation. At 30 days, the adhesion score of RPM@LPS/PVA₁₀-c-PP mesh was 1.37 ± 0.75, however the original PP was 3 ± 0.71. Furthermore, the results of H&E and Masson trichrome staining proved that the RPM@LPS/PVA₁₀-c-PP mesh showed slighter inflammation response and significant looser fibrous tissue surrounded the PP filaments as compared to the native PP. The current findings manifested that this type of RPM@LPS/PVA₁₀-c-PP might be a potential candidate for anti-adhesion treatment. DATA AVAILABILITY: Data will be made available on request.

Light-Activated Chemically Reactive Fibrous Patch Revolutionizes Wound Repair Through the Prevention of Postoperative Adhesion

A light-activated chemically reactive fibrous patch (ChemPatch) with tissue adhesion and wound healing activity was developed for preventing postoperative peritoneal adhesion. ChemPatch was constructed by an integrative electrospinning fabrication strategy, generating multifunctional PCL-NHS fibers encapsulating antioxidant curcumin and MnO₂ nanoparticles. ChemPatch exhibited excellent photothermal conversion, which not only reformed the physical state to match the tissue but also improved conjugation between ChemPatch and tissues, allowing for strong attachment. Importantly, ChemPatch possessed good antioxidant and radical scavenging activity, which protected cells in an oxidative microenvironment and improved tissue regeneration. Particularly, ChemPatch acted as a multifunctional barrier and could not only promote reepithelialization and revascularization in wound defect model but simultaneously ameliorate inflammation and prevent postoperative peritoneal adhesion in a mouse cecal defect model. Thus, ChemPatch represents a dual-active bioadhesive barrier for reducing the incidence and severity of peritoneal adhesions.

PLA and PBAT-Based Electrospun Fibers Functionalized with Antibacterial Bio-Based Polymers

Antimicrobial fibers based on biodegradable polymers, poly(lactic acid) (PLA), and poly(butylene adipate-co-terephthalate) (PBAT) are prepared by electrospinning. For this purpose, a biodegradable/bio-based polyitaconate containing azoles groups (PTTI) is incorporated at 10 wt.% into the electrospinning formulations. The resulting fibers functionalized with azole moieties are uniform and free of beads. Then, the accessible azole groups are subjected to N-alkylation, treatment that provides cationic azolium groups with antibacterial activity at the surface of fibers. The positive charge density, roughness, and wettability of the cationic fibers are evaluated and compared with flat films. It is confirmed that these parameters exert an important effect on the antimicrobial properties, as well as the length of the alkylating agent and the hydrophobicity of the matrix. The quaternized PLA/PTTI fibers exhibit the highest efficiency against the tested bacteria, yielding a 4-Log reduction against S. aureus and 1.7-Log against MRSA. Then, biocompatibility and bioactivity of the fibers are evaluated in terms of adhesion, morphology and viability of fibroblasts. The results show no cytotoxic effect of the samples, however, a cytostatic effect is appreciated, which is ascribed to the strong electrostatic interactions between the positive charge at the fiber surface and the negative charge of the cell membranes.

A sandwiched patch toward leakage-free and anti-postoperative tissue adhesion sealing of intestinal injuries

Ideal repair of intestinal injury requires a combination of leakage-free sealing and postoperative antiadhesion. However, neither conventional hand-sewn closures nor existing bioglues/patches can achieve such a combination. To this end, we develop a sandwiched patch composed of an inner adhesive and an outer antiadhesive layer that are topologically linked together through a reinforced interlayer. The inner adhesive layer tightly and instantly adheres to the wound sites via -NHS chemistry; the outer antiadhesive layer can inhibit cell and protein fouling based on the zwitterion structure; and the interlayer enhances the bulk resilience of the patch under excessive deformation. This complementary trilayer patch (TLP) possesses a unique combination of instant wet adhesion, high mechanical strength, and biological inertness. Both rat and pig models demonstrate that the sandwiched TLP can effectively seal intestinal injuries and inhibit undesired postoperative tissue adhesion. The study provides valuable insight into the design of multifunctional bioadhesives to enhance the treatment efficacy of intestinal injuries.

Punica granatum seed oil detracts peritoneal adhesion: Perusing antioxidant, anti-inflammatory, antifibrotic, and antiangiogenic impacts

Peritoneal adhesion is a significant problem following gastrointestinal surgeries, accompanied by a significant economic burden and morbidity for patients. Punica granatum seed oil (PSO) possesses antioxidative, anti-inflammatory, and anticancer effects. Thus, we aimed to evaluate the antiperitoneal adhesive properties of PSO in rats. Forty-eight Wistar rats (200-250 g) were randomly and equally divided into six groups: sham group, control group; peritoneal adhesion without any treatment, vehicle group; peritoneal adhesion with saline + Tween-80.5% treatment, and experimental groups; peritoneal adhesion with 0.5%, 1.5%, and 4.5% v/v PSO treatment. In addition, peritoneal adhesion was examined macroscopically along with evaluating the oxidative stress (malondialdehyde [MDA], nitric oxide [NO], and glutathione [GSH]) inflammatory (interleukin [IL]-6, IL-1β, and tumor necrosis factor-α [TNF-α]), fibrotic (transforming growth factor-β [TGF-β]), and angiogenic (vascular endothelial growth factor [VEGF]) factors. Our results revealed that the levels of adhesion scores, MDA, NO, IL-6, TNF-α, IL-1β, TGF-β, and VEGF, were propagated in the vehicle group while the GSH level was alleviated (p < 0.001). In contrast, premedication with PSO, especially at the lowest concentration, notably lessened the levels of adhesion scores, MDA, NO, IL-6, TNF-α, IL-1β, TGF-β, and VEGF as well as GSH in comparison to the vehicle group following the peritoneal adhesion induction (p < 0.001-0.05). As a result, PSO may prevent peritoneal adhesion through its antioxidant, anti-inflammatory, antifibrotic, and antiangiogenic properties. Therefore, PSO could be considered a beneficial candidate for the treatment of postoperative peritoneal adhesion.

Evaluation of 20(S)-ginsenoside Rg3 loaded hydrogel for the treatment of perianal ulcer in a rat model

Background

As a kind of common complication of the surgery of perianal diseases, perianal ulcer is known as a nuisance. This study aims to develop a kind of 20(S)-ginsenoside Rg3 (Rg3)-loaded hydrogel to treat perianal ulcers in a rat model.

Methods

The copolymers PLGA₁₆₀₀-PEG₁₀₀₀-PLGA₁₆₀₀ were synthesized by ring-opening polymerization process and Rg3-loaded hydrogel was then developed. The perianal ulcer rat model was established to analyze the treatment efficacy of Rg3-loaded hydrogel for ulceration healing for 15 days. The animals were divided into control group, hydrogel group, free Rg3 group, Rg3-loaded hydrogel group, and Lidocaine Gel® group. The residual wound area rate was calculated and the blood concentrations of interleukin-1 (IL-1), interleukin-6 (IL-6), and vascular endothelial growth factor (VEGF) were recorded. Hematoxylin and eosin (H&E) staining, Masson's Trichrome (MT) staining, and tumor necrosis factor α (TNF-α), Ki-67, CD31, ERK1/2, and NF-κB immunohistochemical staining were performed.

Results

The biodegradable and biocompatible hydrogel carries a homogenous interactive porous structure with 10 μm pore size and five weeks in vivo degradation time. The loaded Rg3 can be released sustainably. The in vitro cytotoxicity study showed that the hydrogel had no effect on survival rate of murine skin fibroblasts L929. The Rg3-loaded hydrogel can facilitate perianal ulcer healing by inhibiting local and systematic inflammatory responses, swelling the proliferation of nuclear cells, collagen deposition, and vascularization, and activating ERK signal pathway.

Conclusion

The Rg3-loaded hydrogel shows the best treatment efficacy of perianal ulcer and may be a candidate for perianal ulcer treatment.

Rapidly Self-Deactivating and Injectable Succinyl Ester-Based Bioadhesives for Postoperative Antiadhesion

Postoperative adhesion not only causes severe complications for patients but also increases their economic burden. Injectable bioadhesives with adhesiveness to tissues can cover irregular wounds and stay stable in situ, which is a promising barrier for antiadhesion. However, the potential tissue adhesion caused by bioadhesives' indiscriminate adhesiveness between normal and wounded tissue is still a problem. Herein, by using poly(ethylene glycol) succinimidyl succinate (PEG-SS) and gelatin, a succinyl ester-based bioadhesive (SEgel) was fabricated with self-deactivating properties for postoperative antiadhesion. Because N-hydroxysuccinimide esters (NHS-esters) were used as the adhesive group, the bioadhesives' side in contact with the tissue built covalent anchors quickly to maintain the stability, but the superficial layer facing outward withstood fast hydrolysis and then lost its adhesion within minutes, avoiding the indiscriminate adhesiveness. In addition, because of the specific degradation behavior of succinyl ester, the SEgel with proper in vivo retention was achieved without the worry of causing foreign body reactions and unexpected tissue adhesion. Both the cecum-sidewall adhesion and hepatic adhesion models showed that the SEgel markedly reduced the severity of tissue adhesion. These results, together with the ease of the preparation process and well-proven biocompatibility of raw materials, revealed that the SEgel might be a promising solution for postoperative antiadhesion.

On-Demand Drug Delivery Systems Using Nanofibers

On-demand drug-delivery systems using nanofibers are extensively applicable for customized drug release based on target location and timing to achieve the desired therapeutic effects. A nanofiber formulation is typically created for a certain medication and changing the drug may have a significant impact on the release kinetics from the same delivery system. Nanofibers have several distinguishing features and properties, including the ease with which they may be manufactured, the variety of materials appropriate for processing into fibers, a large surface area, and a complex pore structure. Nanofibers with effective drug-loading capabilities, controllable release, and high stability have gained the interest of researchers owing to their potential applications in on-demand drug delivery systems. Based on their composition and drug-release characteristics, we review the numerous types of nanofibers from the most recent accessible studies. Nanofibers are classified based on their mechanism of drug release, as well as their structure and content. To achieve controlled drug release, a suitable polymer, large surface-to-volume ratio, and high porosity of the nanofiber mesh are necessary. The properties of nanofibers for modified drug release are categorized here as protracted, stimulus-activated, and biphasic. Swellable or degradable polymers are commonly utilized to alter drug release. In addition to the polymer used, the process and ambient conditions can have considerable impacts on the release characteristics of the nanofibers. The formulation of nanofibers is highly complicated and depends on many variables; nevertheless, numerous options are available to accomplish the desired nanofiber drug-release characteristics.

Prevention of abdominal adhesion by a polycaprolactone/phospholipid hybrid film containing quercetin and silver nanoparticles

Aim: To develop quercetin-loaded poly(caprolactone) (PCL)/soybean phosphatidylcholine (PC) films coated with silver (Ag) to prevent the formation of postoperative adhesions (POA). Materials & methods: Films were prepared using the solvent casting method, coated with Ag, and underwent in vitro tests. In vivo studies were conducted employing an animal model of sidewall defect and cecum abrasion. Results: Films showed sustained release behavior of quercetin and Ag. Coating films with Ag improved their antimicrobial activity. In vivo studies confirmed superior antiadhesion properties of films compared with the control groups evaluated by gross observation, histochemical staining and immunohistochemistry analyses. Conclusion: Ag-Q-PCL-PC films are a potential candidate to prevent POA by acting as a sustained release delivery system and physical barrier.

Physically Cross-Linked Hyaluronan-Based Ultrasoft Cryogel Prepared by Freeze-Thaw Technique as a Barrier for Prevention of Postoperative Adhesions

Postsurgical peritoneal adhesions are a common and serious postoperative complication after various peritoneal surgeries, such as pelvic and abdominal surgery. Various studies have shown that peritoneal adhesions can be minimized or prevented by physical anti-adhesion barriers, including membranes, knits, and hydrogels. Hydrogels have attracted great attention in preventing peritoneal adhesions because the dimensional architecture of hydrogels is similar to that of the native extracellular matrix. However, chemical cross-linkers had to be used in the preparation of chemical hydrogels, which may have problems in cytotoxicity or unwanted side effects. This fact prompts us to create alternative cross-linking methods for the development of biocompatible hydrogels as physical barriers. Herein, we report a physically cross-linked flexible hyaluronan (HA) cryogel prepared via a freeze-thaw technique as a novel anti-adhesion biomaterial for completely preventing postsurgical peritoneal adhesions. In vitro studies demonstrated that this physically cross-linked HA cryogel exhibited excellent biocompatibility, the inherently desirable biocompatibility and functionality of HA being integrally retained as much as possible. Intriguingly, the rheological properties and appropriate biodegradability of the cryogels were readily tailored and tunable by way of the gelation process. In vivo assessments suggested that the cryogel, as a physical barrier, satisfactorily prevented fibroblast penetration and attachment between the injured tissues and nearby normal organs. Furthermore, the molecular mechanism studies revealed that the HA cryogel could prevent peritoneal adhesion by inhibiting inflammatory response and modulation of the fibrinolytic system. Our results show that HA ultrasoft cryogel is a promising clinical candidate for prolonged adhesion prevention.

Application of tumor-targeting peptide-decorated polypeptide nanoparticles with doxorubicin to treat osteosarcoma

Osteosarcoma is the most common primary malignant bone tumor in childhood and adolescence. Currently, surgery combined with chemotherapy is the main treatment for osteosarcoma. However, the long-term survival of patients with metastatic osteosarcoma is unsatisfactory. Therefore, new treatment methods to improve the prognosis of patients with osteosarcoma are required. The present study aimed to develop nanocarriers with both tumor targeting and reduction responsiveness abilities, and to improve the therapeutic effect and reduce toxicity by loading traditional small molecule antitumor drugs. The tumor targeting peptide-decorated, doxorubicin (DOX)-loaded mPEG-P(Phe-co-Cys) nanoparticles were developed successfully through the ring-opening polymerization of amino acids. The peptide VATANST (STP) can specifically bind with vimentin, which is highly expressed on the osteosarcoma cell surface, resulting in tumor targeting effects. The nanoparticle is core–shell structured to protect the loaded DOX during blood flow. The disulfide bonds within the nanoparticles are sensitive to the osteosarcoma microenvironment, which has high glutathione (GSH) levels. Under the enhanced permeability and retention and active tumor targeting effects, the STP-decorated DOX-loaded nanoparticles accumulated in tumor tissues. High GSH levels can rupture disulfide bonds, resulting in the controlled release of DOX, which will cause necrosis of tumor cells. The characteristics of the synthesized nanoparticles, DOX release profiles in vitro and in vivo, cytotoxicity analysis, animal study, and safety evaluation were performed. The nanoparticles could increase the tumor inhibition efficiency against osteosarcoma and reduce the side effects of DOX to major organs. The STP-decorated mPEG-P(Phe-co-Cys) nanoparticles might be a suitable drug delivery system for DOX to treat osteosarcoma.

Standardised pomegranate peel extract lavage prevents postoperative peritoneal adhesion by regulating TGF-β and VEGF levels

Peritoneal adhesion represents a severe complication following surgery. Punica granatum (pomegranate) possesses several anti-oxidative and anti-inflammatory properties. Pomegranate peel extract (PPEx) can alleviate the production of various inflammatory factors and cytokines. Thus, we sought to evaluate the anti-adhesion effects of pomegranate in rats. Thirty male Wistar rats (6-week-old, 220 ± 20 g) were divided into five groups (n = 6): normal group without any surgical procedures, control group, and experimental groups receiving 2 ml of 1%, 2%, and 4% w/v PPEx, respectively. Peritoneal adhesions were examined macroscopically. Furthermore, we evaluated inflammatory cytokines levels [interleukin 6 (IL-6), and tumour necrosis factor-α (TNF-α)], growth factors [transforming growth factor- β1 (TGF-β1), and vascular endothelial growth factor (VEGF)], and oxidative stress parameters [nitric oxide metabolites (NO), and malondialdehyde (MDA), and glutathione (GSH)] using biochemical methods. Our results showed that the adhesion score and IL-6, TNF-α, TGF-β1, VEGF, NO, and MDA levels were increased in the control group. In contrast, the GSH level was diminished in the control group compared with the normal group (P < 0.001). PPEx (1 and 2% w/v) markedly reduced all measured parameters compared with the control group (P < 0.001-0.05). PPEx may reduce peritoneal adhesion by alleviating adhesion formation, IL-6, TNF-α, TGF-β1, VEGF, NO, and MDA, and stimulating anti-oxidative factors. Therefore, PPEx may be considered an appropriate candidate for the treatment of postoperative peritoneal adhesion.

Advanced technology-driven therapeutic interventions for prevention of tendon adhesion: Design, intrinsic and extrinsic factor considerations

Tendon adhesion formation describes the development of fibrotic tissue between the tendon and its surrounding tissues, which commonly occurs as a reaction to injury or surgery. Its impact on function and quality of life varies from negligible to severely disabling, depending on the affected area and extent of adhesion formed. Thus far, treatment options remain limited with prophylactic anti-inflammatory medications and revision surgeries constituting the only tools within the doctors' armamentarium - neither of which provides reliable outcomes. In this review, the authors aim to collate the current understanding of the pathophysiological mechanisms underlying tendon adhesion formation, highlighting the significant role ascribed to the inflammatory cascade in accelerating adhesion formation. The bulk of this article will then be dedicated to critically appraising different therapeutic structures like nanoparticles, hydrogels and fibrous membranes fabricated by various cutting-edge technologies for adhesion formation prophylaxis. Emphasis will be placed on the role of the fibrous membranes, their ability to act as drug delivery vehicles as well as the combination with other therapeutic structures (e.g., hydrogel or nanoparticles) or fabrication technologies (e.g., weaving or braiding). Finally, the authors will provide an opinion as to the future direction of the prevention of tendon adhesion formation in view of scaffold structure and function designs.

Electrospraying as a novel process for the synthesis of particles/nanoparticles loaded with poorly water-soluble bioactive molecules

Hydrophobicity and low aqueous-solubility of different drugs/nutraceuticals remain a persistent challenge for their development and clinical/food applications. A range of nanotechnology strategies have been implemented to address this issue, and amongst which a particular emphasis has been made on those that afford an improved biological performance and tunable release kinetic of bioactives through a one-step process. More recently, the technique of electrospraying (or electrohydrodynamic atomization) has attained notable impulse in virtue of its potential to tune attributes of nano/micro-structured particles (e.g., porosity, particle size, etc.), rendering a near zero-order release kinetics, diminished burst release manner, as well as its simplicity, reproducibility, and applicability to a broad spectrum of hydrophobic and poorly water-soluble bioactives. Controlled morphology or monodispersity of designed particles could be properly obtained via electrospraying, with a high encapsulation efficiency and without unfavorable denaturation of thermosensitive bioactives upon encapsulation. This paper overviews the recent technological advances in electrospraying for the encapsulation of low queues-soluble bioactive agents. State-of-the-art, advantages, applications, and challenges for its implementation in pharmaceutical/food researches are also discussed.

Biodegradable Zwitterionic Cream Gel for Effective Prevention of Postoperative Adhesion

Postoperative peritoneal adhesions were frequent complications for almost any types of abdominal and pelvic surgery. This led to numerous medical problems and huge financial burden to the patients. Current anti-adhesion strategies focused mostly on physical barriers including films and hydrogels. However, they can only alleviate or reduce adhesions to certain level and their applying processes were far from ideal. This work reported the development of a biodegradable zwitterionic cream gel presenting a series of characters for an idea anti-adhesion material, including unique injectable yet malleable and self-supporting properties, which enabled an instant topical application, no curing, waiting or suturing, no hemostasis requirement, protein/cell resistance and biodegradability. The cream gel showed a major advancement in anti-adhesion efficacy by completely and reliably preventing a primary and a more severe recurrent adhesion in rat models.

Multidrug-loaded electrospun micro/nanofibrous membranes: Fabrication strategies, release behaviors and applications in regenerative medicine

Electrospun micro/nanofibrous membranes (EFMs) have been widely investigated as local drug delivery systems. Multiple drugs can be simultaneously incorporated into one EFM to create synergistic effects, reduce side effects, and play their respective roles in the complex physiological processes of tissue regeneration and postoperative adhesion prevention. Due to the versatile electrospinning techniques, sustained and programmed release behaviors of multiple drugs could be achieved by modulating the structure of the EFMs and the location of the drugs. In this review, various multidrug incorporation approaches based on electrospinning are overviewed. In particular, the advantages and limitations of each drug incorporation technique, the methods to control drug release and the effect of one drug release on another are discussed. Then the applications of multidrug-loaded EFMs in regenerative medicine, including wound healing, bone regeneration, vascular tissue engineering, nerve regeneration, periodontal regeneration and adhesion prevention are comprehensively reviewed. Finally, the future perspectives and challenges in the research of multidrug-loaded EFMs are discussed.

Advancement of Biomaterial-Based Postoperative Adhesion Barriers

Postoperative peritoneal adhesion (PPA) is a prevalent incidence that generally happens during the healing process of traumatized tissues. It causes multiple severe complications such as intestinal obstruction, chronic abdominal pain, and female infertility. To prevent PPA, several antiadhesion materials and drug delivery systems composed of biomaterials are used clinically, and clinical antiadhesive is one of the important applications nowadays. In addition to several commercially available materials, like film, spray, injectable hydrogel, powder, or solution type have been energetically studied based on natural and synthetic biomaterials such as alginate, hyaluronan, cellulose, starch, chondroitin sulfate, polyethylene glycol, polylactic acid, etc. Moreover, many kinds of animal adhesion models, such as cecum abrasion models and unitary horn models, are developed to evaluate new materials' efficacy. A new animal adhesion model based on hepatectomy and conventional animal adhesion models is recently developed and a new adhesion barrier by this new model is also developed. In summary, many kinds of materials and animal models are studied; thus, it is quite important to overview this field's current progress. Here, PPA is reviewed in terms of the species of biomaterials and animal models and several problems to be solved to develop better antiadhesion materials in the future are discussed.

Fouling-resistant zwitterionic polymers for complete prevention of postoperative adhesion

Postoperative adhesions are most common issues for almost any types of abdominal and pelvic surgery, leading to adverse consequences. Pharmacological treatments and physical barrier devices are two main approaches to address postoperative adhesions but can only alleviate or reduce adhesions to some extent. There is an urgent need for a reliable approach to completely prevent postoperative adhesions and to significantly improve the clinical outcomes, which, however, is unmet with current technologies. Here we report that by applying a viscous, cream-like yet injectable zwitterionic polymer solution to the traumatized surface, postoperative adhesion was completely and reliably prevented in three clinically relevant but increasingly challenging models in rats. The success rate of full prevention is over 93% among 42 animals tested, which is a major leap in antiadhesion performance. Clinically used Interceed film can hardly prevent the adhesion in any of these models. Unlike current antiadhesion materials serving solely as physical barriers, the "nonfouling" zwitterionic polymer functioned as a protective layer for antiadhesion applications with the inherent benefit of resisting protein/cell adhesions. The nonfouling nature of the polymer prevented the absorption of fibronectins and fibroblasts, which contribute to the initial and late-stage development of the adhesion, respectively. This is the key working mechanism that differentiated our "complete prevention" approach from current underperforming antiadhesion materials. This work implies a safe, effective, and convenient way to fully prevent postoperative adhesions suffered by current surgical patients.

Effects of Morphologies of Thermosensitive Electrospun Nanofibers on Controllable Drug Release

Electrospun nanofibers is a promising and versatile avenue for building controlled drug release system because of the facile fabrication and the broad range of polymer materials. This research systematically studied the morphological effect of thermosensitive electrospun nanofibers, including porous and coaxial structures, on controllable drug release. Three types of drugs, nicotinamide, paracetamol, and ibuprofen, with different hydrophilicity were applied in this study. The data of drug release were all fitted to the first-order kinetic model regardless of the drug properties, and the release rates paralleled with their hydrophilicity. Sol-gel phase transition of the thermosensitive poly(N-isopropylacrylamide) (PNIPAAm) hydrogel led to slower drug release at 37°C compared with those at 25°C. Regarding morphology, coaxial nanofibers could provide higher loading efficiency and slower drug release rather than porous nanofibers. Our research highlighted the overall effects of compound property, temperature, and the morphological structures of thermosensitive electrospun nanofibers on the controlled drug release. Our results concluded that hydrophobic drug encapsulated in the core-shell PNIPAAm nanofibers could perform excellent sustained release and also controllable release under temperature stumuli. Impact statement The behaviors for the controlled release of drugs loaded in the thermosensitive electrospun nanofibers could be affected by various factors including the properties of loaded drug, morphologies of nanofibrous, and lower critical solution temperatures of thermosensitive hydrogels. However, few systematical investigations have been performed in this area. In this article, we designed and fabricated porous and coaxial thermosensitive poly(N-isopropylacrylamide) electrospun nanofibers with different drug loading to study the comprehensive effect. This study suggested when adopting thermosensitive electrospun hydrogel nanofibers as the controllable drug release carrier, the hydrophilicity of loaded compounds and the morphologies of nanofibers are necessary to be optimized.

Potential of a facile sandwiched electrospun scaffold loaded with ibuprofen as an anti-adhesion barrier

The combination of nanofibre-based barriers and anti-adhesion drugs is potentially useful for adhesion prevention after ventral surgeries. However, drug molecules exposed to the surface of barriers easily result in an initial burst that is sharp, thus limiting the anti-adhesion efficiency. In this study, we developed a sandwiched electrospun scaffold loaded with ibuprofen (Sandwich) serving as a physical barrier, as well as an effectual carrier delivering it into the injured site for enhancing anti-adhesion capability. This Sandwich scaffold exhibited significantly a reduced initial burst of drug release in the first hour and a prolonged delivery for ibuprofen over 14 days, expected to provide the long-term anti-adhesion capability. In vitro study on fibroblasts showed that incorporation of ibuprofen effectively inhibited their adhesion and proliferation, and developed Sandwich maintained the least adhesion of L-929 after 5 days of culture (<20%). For RAW 264.7 macrophages, worse cell adhesion and poorer TNF-α production of Sandwich indicated its superior anti-inflammatory effect. In summary, the sandwiched ibuprofen-loaded scaffold showed promising potential for preventing adhesion formation.

Blood Oxygenation Using Fluoropolymer-Based Artificial Lung Membranes

Artificial lung (AL) membranes are used for blood oxygenation for patients undergoing open-heart surgery or acute lung failures. Current AL technology employs polypropylene and polymethylpentene membranes. Although effective, these membranes suffer from low biocompatibility, leading to undesired blood coagulation and hemolysis over a long term. In this work, we propose a new generation of AL membranes based on amphiphobic fluoropolymers. We employed poly(vinylidene-co-hexafluoropropylene), or PVDF-co-HFP, to fabricate macrovoid-free membranes with an optimal pore size range of 30-50 nm. The phase inversion behavior of PVDF-co-HFP was investigated in detail for structural optimization. To improve the wetting stability of the membranes, the fabricated membranes were coated using Hyflon AD60X, a type of fluoropolymer with an extremely low surface energy. Hyflon-coated materials displayed very low protein adsorption and a high contact angle for both water and blood. In the hydrophobic spectrum, the data showed an inverse relationship between the surface free energy and protein adsorption, suggesting an appropriate direction with respect to biocompatibility for AL research. The blood oxygenation performance was assessed using animal sheep blood, and the fabricated fluoropolymer membranes showed competitive performance to that of commercial polyolefin membranes without any detectable hemolysis. The data also confirmed that the bottleneck in the blood oxygenation performance was not the membrane permeance but rather the rate of mass transfer in the blood phase, highlighting the importance of efficient module design.

Bio-Based Electrospun Fibers for Wound Healing

Being designated to protect other tissues, skin is the first and largest human body organ to be injured and for this reason, it is accredited with a high capacity for self-repairing. However, in the case of profound lesions or large surface loss, the natural wound healing process may be ineffective or insufficient, leading to detrimental and painful conditions that require repair adjuvants and tissue substitutes. In addition to the conventional wound care options, biodegradable polymers, both synthetic and biologic origin, are gaining increased importance for their high biocompatibility, biodegradation, and bioactive properties, such as antimicrobial, immunomodulatory, cell proliferative, and angiogenic. To create a microenvironment suitable for the healing process, a key property is the ability of a polymer to be spun into submicrometric fibers (e.g., via electrospinning), since they mimic the fibrous extracellular matrix and can support neo- tissue growth. A number of biodegradable polymers used in the biomedical sector comply with the definition of bio-based polymers (known also as biopolymers), which are recently being used in other industrial sectors for reducing the material and energy impact on the environment, as they are derived from renewable biological resources. In this review, after a description of the fundamental concepts of wound healing, with emphasis on advanced wound dressings, the recent developments of bio-based natural and synthetic electrospun structures for efficient wound healing applications are highlighted and discussed. This review aims to improve awareness on the use of bio-based polymers in medical devices.

Preparation and modeling of three-layered PCL/PLGA/PCL fibrous scaffolds for prolonged drug release

The authors present the preparation procedure and a computational model of a three‐layered fibrous scaffold for prolonged drug release. The scaffold, produced by emulsion/sequential electrospinning, consists of a poly(d,l-lactic-co-glycolic acid) (PLGA) fiber layer sandwiched between two poly(ε-caprolactone) (PCL) layers. Experimental results of drug release rates from the scaffold are compared with the results of the recently introduced computational finite element (FE) models for diffusive drug release from nanofibers to the three-dimensional (3D) surrounding medium. Two different FE models are used: (1) a 3D discretized continuum and fibers represented by a simple radial one-dimensional (1D) finite elements, and (2) a 3D continuum discretized by composite smeared finite elements (CSFEs) containing the fiber smeared and surrounding domains. Both models include the effects of polymer degradation and hydrophobicity (as partitioning) of the drug at the fiber/surrounding interface. The CSFE model includes a volumetric fraction of fibers and diameter distribution, and is additionally enhanced by using correction function to improve the accuracy of the model. The computational results are validated on Rhodamine B (fluorescent drug l) and other hydrophilic drugs. Agreement with experimental results proves that numerical models can serve as efficient tools for drug release to the surrounding porous medium or biological tissue. It is demonstrated that the introduced three-layered scaffold delays the drug release process and can be used for the time-controlled release of drugs in postoperative therapy.

Electrospun nanofibers for the delivery of active drugs through nasal, oral and vaginal mucosa: Current status and future perspectives

Transmucosal surfaces bypass many limitations associated with conventional drug delivery (oral and parenteral routes), such as poor absorption rate, enzymatic activity, acidic environment and first-pass metabolism occurring inside the liver. However, these surfaces have several disadvantages such as poor retention time, narrow absorption window and continuous washout of the drug by the surrounding fluids. Electrospun nanofibers with their unique surface properties and encapsulation efficiency may act as novel drug carriers to overcome the challenges associated with conventional drug delivery routes, so as to achieve desired therapeutic responses. This review article provides detailed information regarding the challenges faced in the mucosal delivery of drugs, and the use of nanofiber systems as an alternative to deliver drugs to the systemic circulation, as well as local drug administration. The physiological and anatomical features of different types of mucosal surfaces and current challenges are systematically discussed. We also address future considerations in the area of transmucosal delivery of some important drugs.

Controlled release of Mitomycin C from modified cellulose based thermo-gel prevents post-operative de novo peritoneal adhesion

The complications from surgery associated peritoneal adhesion can be alleviated by combination of physical isolation and pharmaceutical treatment. This work aims to develop thermo-sensitive hydrogel barrier by combining mitomycin C (MMC) with modified tempo oxidized nanocellulose (cTOCN) through EDC/NHS-chemical conjugation followed by integration with methyl cellulose (MC). The MMC was successfully combined with cTOCN and ensured controlled release of MMC from hydrogel throughout 14 days. Amount of MC (1.5, 2.5, 3.5% w/v) was proportional to gelation time and inversely proportional to degradation of hydrogel. The optimized hydrogel (C2.5T1M0.2) needed only 30 s for thermoreversible sol-gel (4℃-37℃) phenomenon and did not show in vitro fibroblast cells toxicity as well as ensured complete adhesion prevention efficacy, reperitonealization in rat side wall-cecal abrasion model. Overall, the developed C2.5T1M0.2 thermo-gel advances state-of-the-art in view of cytocompatibility, mechanical stability, optimum degradation, good injectability, sustain drug release from surgical sites, and satisfactory de novo anti-adhesion capacity.

Biologically Targeted Photo-Crosslinkable Nanopatch to Prevent Postsurgical Peritoneal Adhesion

Peritoneal adhesion occurs in a majority of patients following abdominal surgery and can result in significant side effects and complications. Current strategies to minimize adhesions involve the use of nontargeted anatomical barriers that are either inefficient in protecting injured areas or lacking the adequate residence time to prevent adhesions. Herein, the development of a biologically targeted photo-crosslinkable nanopatch (pCNP) is reported that can prevent postsurgical adhesion. It is demonstrated that pCNP can form a compact protective barrier over surfaces with exposed collagen IV. Using a rat parietal peritoneal excision adhesion model, it is showed that pCNP is highly effective and safe in preventing postsurgical adhesions. This work presents a novel approach to preventing peritoneal adhesion with nanomaterials.

Recent Progress in Polyhydroxyalkanoates-Based Copolymers for Biomedical Applications

In recent years, naturally biodegradable polyhydroxyalkanoate (PHA) monopolymers have become focus of public attentions due to their good biocompatibility. However, due to its poor mechanical properties, high production costs, and limited functionality, its applications in materials, energy, and biomedical applications are greatly limited. In recent years, researchers have found that PHA copolymers have better thermal properties, mechanical processability, and physicochemical properties relative to their homopolymers. This review summarizes the synthesis of PHA copolymers by the latest biosynthetic and chemical modification methods. The modified PHA copolymer could greatly reduce the production cost with elevated mechanical or physicochemical properties, which can further meet the practical needs of various fields. This review further summarizes the broad applications of modified PHA copolymers in biomedical applications, which might shred lights on their commercial applications.

Exploiting Viscoelastic Experimental Observations and Numerical Simulations to Infer Biomimetic Artificial Tendon Fiber Designs

Designing biomimetic artificial tendons requires a thorough, data-based understanding of the tendon's inner material properties. The current work exploits viscoelastic experimental observations at the tendon fascicle scale, making use of mechanical and data analysis methods. More specifically, based on reported elastic, volumetric and relaxation fascicle scale properties, we infer most probable, mechanically compatible material attributes at the fiber scale. In particular, the work provides pairs of elastic and viscous fiber-scale moduli, which can reproduce the upper scale tendon mechanics. The computed range of values for the fiber-scale tendon viscosity attest to the substantial stress relaxation capabilities of tendons. More importantly, the reported mechanical parameters constitute a basis for the design of tendon-specific restoration materials, such as fiber-based, engineering scaffolds.

Drug Delivery From Polymer-Based Nanopharmaceuticals-An Experimental Study Complemented by Simulations of Selected Diffusion Processes

The success of medical therapy depends on the correct amount and the appropriate delivery of the required drugs for treatment. By using biodegradable polymers a drug delivery over a time span of weeks or even months is made possible. This opens up a variety of strategies for better medication. The drug is embedded in a biodegradable polymer (the "carrier") and injected in a particular position of the human body. As a consequence of the interplay between the diffusion process and the degrading polymer the drug is released in a controlled manner. In this work we study the controlled release of medication experimentally by measuring the delivered amount of drug within a cylindrical shell over a long time interval into the body fluid. Moreover, a simple continuum model of the Fickean type is initially proposed and solved in closed-form. It is used for simulating some of the observed release processes for this type of carrier and takes the geometry of the drug container explicitly into account. By comparing the measurement data and the model predictions diffusion coefficients are obtained. It turns out that within this simple model the coefficients change over time. This contradicts the idea that diffusion coefficients are constants independent of the considered geometry. The model is therefore extended by taking an additional absorption term into account leading to a concentration dependent diffusion coefficient. This could now be used for further predictions of drug release in carriers of different shape. For a better understanding of the complex diffusion and degradation phenomena the underlying physics is discussed in detail and even more sophisticated models involving different degradation and mass transport phenomena are proposed for future work and study.

Gradiently degraded electrospun polyester scaffolds with cytostatic for urothelial carcinoma therapy

Gradiently degraded cytostatic-loaded electrospun polyester scaffolds as potential self-removing ureteral stents prevent the recurrence of urothelial carcinoma.

A Computational Model for Drug Release from PLGA Implant

Due to the relative ease of producing nanofibers with a core⁻shell structure, emulsion electrospinning has been investigated intensively in making nanofibrous drug delivery systems for controlled and sustained release. Predictions of drug release rates from the poly (d,l-lactic-co-glycolic acid) (PLGA) produced via emulsion electrospinning can be a very difficult task due to the complexity of the system. A computational finite element methodology was used to calculate the diffusion mass transport of Rhodamine B (fluorescent drug model). Degradation effects and hydrophobicity (partitioning phenomenon) at the fiber/surrounding interface were included in the models. The results are validated by experiments where electrospun PLGA nanofiber mats with different contents were used. A new approach to three-dimensional (3D) modeling of nanofibers is presented in this work. The authors have introduced two original models for diffusive drug release from nanofibers to the 3D surrounding medium discretized by continuum 3D finite elements: (1) A model with simple radial one-dimensional (1D) finite elements, and (2) a model consisting of composite smeared finite elements (CSFEs). Numerical solutions, compared to experiments, demonstrate that both computational models provide accurate predictions of the diffusion process and can therefore serve as efficient tools for describing transport inside a polymer fiber network and drug release to the surrounding porous medium.