Polycaprolactone-based biomaterials for tissue engineering and drug delivery: Current scenario and challenges

4D printing polymeric biomaterials for adaptive tissue regeneration

4D printing polymeric biomaterials can change their morphology or performance in response to stimuli from the external environment, compensating for the shortcomings of traditional 3D-printed static structures. This paper provides a systematic overview of 4D printing polymeric biomaterials for tissue regeneration and provides an in-depth discussion of the principles of these materials, including various smart properties, unique deformation mechanisms under stimulation conditions, and so on. A series of typical polymeric biomaterials and their composites are introduced from structural design and preparation methods, and their applications in tissue regeneration are discussed. Finally, the development prospect of 4D printing polymeric biomaterials is envisioned, aiming to provide innovative ideas and new perspectives for their more efficient and convenient application in tissue regeneration.

Electrospun Decellularized Skeletal Muscle Tissue/Polycaprolactone/Polyaniline as a Potential Scaffold for Muscle Tissue Engineering

Skeletal muscle tissue is capable of self-healing on a small scale. However, during extensive trauma or surgery, regenerative capacities are lost due to the loss of muscle cells and extracellular matrix. Therefore, the development of tissue engineering strategies for the regeneration of muscle tissue should be considered. In this study, we electrospun decellularized skeletal muscle tissue (DSM)/polycaprolactone (PCL)/polyaniline (PANi) as a bioactive polymer composite and investigated the structural characteristics, physicochemical properties, and effect of PANi on these properties. Next, the biological and myogenic effects of scaffolds on human Wharton's jelly mesenchymal stem cells (hWJ-MSCs) were investigated. The results showed that DSM/PCL/PANi is a conductive fibrous scaffold with favorable physical and chemical properties for muscle tissue engineering; it is biocompatible with hWJ-MSCs and stimulates their morphology. Additionally, hWJ-MSCs cultured on DSM/PCL/PANi showed a significant increase in the expression of MyoD, Myogenin, and MHC. Laboratory experiments showed that the electrospun scaffold of DSM/PCL/PANi is biocompatible with favorable physical properties for the growth of stem cells and the expression of myogenic markers, which can be useful in the development of biological scaffold approaches for muscle tissue engineering.

Biocompatible composites based on alginate, polycaprolactone, and nanocellulose - A review

Biocompatible composite materials are gaining attention for biomedical applications due to their biodegradability, mechanical strength, and tunability. The fabrication techniques and applications significantly impact composite performance. This paper explores the synthesis of composites from alginate, polycaprolactone (PCL), and nanocellulose, emphasizing their distinct properties for biomedical use. Alginate provides excellent biocompatibility and gelling ability, PCL offers controlled mechanical strength, and nanocellulose enhances stability due to its superior mechanical properties. Key fabrication techniques include solution mixing, hot pressing, melt mixing/extrusion, electrospinning, and 3D printing, each influencing structural integrity, mechanical properties, and material dispersion. Optimizing fabrication methods is crucial for achieve desirable properties in specific applications. The choice of synthesis technique directly affects the final use, such as drug delivery systems, tissue engineering scaffolds, or wound dressings. This review discusses the challenges and prospects of developing alginate-, PCL-, and nanocellulose-based composites, offering insights into their future biomedical applications.

Synthesis, Characterization, and Osteogenic Ability of Fibrillar Polycaprolactone Scaffolds Containing Hydroxyapatite Nanoparticles

Polymer-based scaffolds for bone regeneration aim to mimic the structure and function of the collagen-rich extracellular matrix. Hydroxyapatite incorporated into these biomaterials improves their mechanical and biological properties due to its bioactive osteoconductive nature. The objectives of this study are to synthesize and characterize polycaprolactone (PCL) scaffolds containing hydroxyapatite nanoparticles (HAn) at 1, 2.5, 5, and 7% concentrations and to determine their cytocompatibility and osteogenic potential. Fiber thickness (n = 240) and interfibrillar space (n = 8) of PCL scaffolds were characterized by scanning electron microscopy (SEM). The PCL scaffolds were evaluated concerning their thermal degradation (TGA), calcium release, and hydrophilicity (WCA). Preosteoblasts were seeded on PCL scaffolds and assessed regarding their viability (AlamarBlue, n = 8), collagen synthesis (SR, n = 8), total protein synthesis (TP, n = 8), alkaline phosphatase activity (ALP, n = 8), deposition of mineralization nodules (MN, n = 8), and cell adhesion (fluorescence microscopy). The data analyses of the biomaterials, including TGA, energy dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR), were interpreted descriptively. The quantitative data were statistically analyzed (α = 5%). Scaffolds without HAn exhibited thicker fibers. The higher incorporation of HAn in the PCL scaffolds increased the interfibrillar spaces and resulted in greater P and Ca peaks (p < 0.05), as well as broader peaks representing the P-O group (FTIR). TGA demonstrated that PCL scaffold degradation was inversely proportional to their HAn concentration. Higher percentages of cell viability were observed with the incorporation of HAn. ALP activity increased in cells seeded onto PCL scaffolds containing 2.5% HAn. Deposition of MN was directly proportional to the amount of HAn incorporated. HAn incorporated into PCL scaffolds interferes with the physicochemical properties of these biomaterials and favors in vitro osteogenesis.

The role of polymer type and surfactant composition on the toxicological profile of nanoparticles: an in vitro comparative study

Nanotechnology is expanding rapidly, leading to the continual development of new applications. Therefore, it is crucial to understand the effects of nanoparticles (NPs) and their components to develop more efficient formulations with greater potential applications. Here, we evaluated the influence of polymer and surfactant composition on NP toxicity. Our results revealed significant variations in toxicity based on NP composition. The type of polymer used to prepare the NPs affects their properties, especially in terms of cell tolerance. Notably, cell viability ranged from 6% to 100% depending on the NPs' composition. In general, NPs based on Eudragit® RL 100 exhibited greater cytotoxicity and hemolysis rates than those based on PCL, PLGA, and chitosan. This highlights the critical role of polymer selection in determining toxicity. Additionally, including Span 80® in the NP matrix amplified its toxic effects, which emphasizes the importance of surfactant choice in NP design. Both nanospheres and nanocapsules based on the same polymer displayed comparable toxicological profiles. Although smaller NPs exhibited higher toxicity, a direct correlation between size and toxicity could not be established, since the increased toxicity of smaller NPs was primarily attributed to the presence of Span 80® in the composition. Finally, all formulations, except the nanospheres based on Eudragit® RL 100, maintained colloidal stability in a protein-rich environment, indicating that no secondary structures were formed. Therefore, our data suggest that NP constituents can critically contribute to its toxicity, highlighting the importance of toxicological and safety studies to better understand the effects of nanoformulations.

Controlled release of bioactive copper (I) acylthiourea complexes through immobilization onto electrospun PCL/lignin nanofibers

This study presents the first development of Cu (I) acylthiourea complexes (C1-C5) incorporated polycaprolactone/lignin (PCL/Lig) electrospun nanofiber composites (PCL/Lig@Cu(I)). Electrospinning conditions and mass ratios of PCL and lignin were optimized, followed by the incorporation of varying concentrations of Cu(I) complexes. Structural, morphological, and thermal properties were characterized using SEM, TEM, FT-IR, XRD, TGA and WCA analyses. Mechanical properties, release behavior and antibacterial activity were also assessed. Results confirmed the successful incorporation of Cu-complex into PCL/Lignin nanofiber composites. The PCL/Lig@Cu(I) composite membranes exhibited excellent thermal stability. After incorporating Cu complex into PCL/Lig membranes, the hydrophobicity was found to be enhanced by approximately 5 %. The PCL/Lig@C4 exhibited a stable and continuous release of Cu-complex until the initial 12 h, but after that there was a decrease in the release by 21.27, 26.07 and 24.41 % was observed for the samples PCL/Lig@C4-1%, 2 % and 3 % respectively. To our delight, the PCL/Lig@C4-1% showed a very controlled and steady release of bioactive Cu(I)-complex for a very long period of time (20 days). Overall, our study demonstrates the feasibility of using acylthiourea Cu (I) complexes (C1-C5) immobilized PCL/Lig nanofiber composites for biomedical applications requiring controlled release and antibacterial activity.

Advances in Conductive Biomaterials for Cardiac Tissue Engineering: Design, Fabrication, and Functional Integration

Heart failure functions as one of the leading global causes of death because it falls under the cardiovascular disease categories. Cardiac tissue engineering advances by developing new tissues to rebuild heart functions in individuals with damaged heart structures as it gives medical treatment possibilities to patients reaching their final stage. Most of the heart tissue consists of cardiomyocytes which make up between 80 to 90 percent of the total organ space. The cardiomyocytes retain their specialized cell structure which includes elongation, but they align to produce contractions as they span into length. After myocardial infarction, doctors need elastic soft platforms to heal the heart tissue because they mimic its natural attributes. Special consideration must be paid to the material selection for appropriate mechanical properties, given that different substances have separate qualities. Stem cell survival becomes higher, and cell differentiation develops more efficiently when a proper scaffold design is implemented, thus enabling tissue repair. Conductive biomaterials demonstrate the best candidate status for cardiac tissue engineering due to their ability to both convey electrical signals and boost biological actions as well as promote cellular communication. Scientists conduct life science research on stem cells because the cells present unique characteristics. Biomaterials with conductive properties within cardiac tissue engineering help the body recover heart tissue while improving the functionality of damaged structures in the myocardium. This article analyzes various conductive biomaterials used in biomedical practices for cardiac tissue healing applications.

Development and Characterization of Innovative Nifurtimox Formulations as Therapeutic Alternative for Chagas Disease

Chagas disease, caused by Trypanosoma cruzi, remains a neglected tropical disease with limited and often suboptimal chemotherapeutic treatment options. The WHO recommends nifurtimox (NFX) for treating Chagas disease, which, although it is effective in the early stages of infection, has variable efficacy in the chronic phase and induces adverse effects that frequently compromise the continuity of the treatment. This study focused on the development and characterization of innovative lipid-based self-emulsifying drug delivery systems (SEDDSs) and poly(ε-caprolactone) implants containing NFX. The SEDDS formulations modified the NFX release extent and rate. The implant characterization included thermal analysis, X-ray diffraction, thermo-optical analysis, and scanning electron microscopy, confirming the low interaction between NFX and the polymer. In vitro assays demonstrated the enhanced anti-T. cruzi activity of the NFX-SEDDS, with minimal cytotoxicity in mammalian cells. In vivo studies using T. cruzi-infected mice revealed that both formulations effectively suppressed parasitemia, achieving cure rates comparable to those of the standard oral NFX treatment. Additionally, the implants showed improved tolerability and sustained efficacy, delivering a prolonged effect equivalent to 40 oral doses. These findings highlight the potential of these innovative NFX formulations as promising alternatives for treating Chagas disease, particularly in the chronic phase, offering improved adherence and comparable efficacy to the existing therapies.

Triple-layered encapsulation of sensitive biomolecules into poly (ε-caprolactone) nanofibers using AC electrospraying

The incorporation of sensitive bioactive substances such as proteins or DNA into nanofibers poses a significant problem due to the toxicity of most organic solvents. The main idea of this study is to use alternating current electrospraying to create a suspension consisting of polyvinyl alcohol (PVA) capsules containing a bioactive substance dispersed in a solvent system suitable for a water-insoluble biocompatible polymer. In this suspension consisting of PVA capsules and a chloroform/ethanol mixture, poly (ε-caprolactone) (PCL) was dissolved and spun by needle-free electrospinning. The result is a fibrous PCL structure in which PVA capsules containing the bioactive agent are integrated. The PVA capsules protect the bioactive substance from the organic solvents needed to dissolve the PCL. To verify the efficacy of the capsules' protection against chloroform, the green fluorescent protein was first encapsulated into the nanofibers, followed by horseradish peroxidase. Both molecules were shown to retain their bioactivity within the nanofibers.

Development of 4D-Printed Arterial Stents Utilizing Bioinspired Architected Auxetic Materials

The convergence of 3D printing and auxetic materials is paving the way for a new era of adaptive structures. Auxetic materials, known for their unique mechanical properties, such as a negative Poisson's ratio, can be integrated into 3D-printed objects to enable them to morph or deform in a controlled manner, leading to the creation of 4D-printed structures. Since the first introduction of 4D printing, scientific interest has spiked in exploring its potential implementation in a wide range of applications, from deployable structures for space exploration to shape-adaptive biomechanical implants. In this context, the current paper aimed to develop 4D-printed arterial stents utilizing bioinspired architected auxetic materials made from biocompatible and biodegradable polymeric material. Specifically, three different auxetic materials were experimentally examined at different relative densities, under tensile and compression testing, to determine their mechanical behavior. Based on the extracted experimental data, non-linear hyperelastic finite element material models were developed in order to simulate the insertion of the stent into a catheter and its deployment in the aorta. The results demonstrated that among the three examined structures, the 'square mode 3' structure revealed the best performance in terms of strength, at the same time offering the necessary compressibility (diameter reduction) to allow insertion into a typical catheter for stent procedures.

The role of biomaterials-based scaffolds in advancing skin tissue construct

Despite extensive clinical studies and therapeutic interventions, addressing significant skin wounds remains challenging, necessitating novel approaches for effective regeneration therapy. In the current review, we analyzed and evaluated the application, advancements, and future directions of biomaterials-based scaffolds for skin tissue construct. In addition, we investigated the role of other biological substitutes in promoting wound healing and skin tissue regeneration. The review highlights the impact of biomaterial-based scaffolds on skin tissue regeneration and wound healing. After presenting the physiological process of skin tissue regeneration, the review emphasizes the different biochemical components significant for skin healing and regeneration. Subsequently, it delves into the role of scaffolds in skin tissue engineering. Recent advancements in nanotechnology are also highlighted with a specific focus on the utilization of nanomaterials for enhancing healing, facilitating tissue regeneration, and promoting skin reconstruction. Biomaterial scaffolds have emerged as a potential intervention for wound healing forming the foundation of skin tissue regeneration. These scaffolds, intricate three-dimensional frameworks, serve as carriers for cells, medications, and genes, facilitating their delivery into the body. The integration of degradable porous scaffolds with biological cells offers a promising avenue for tissue repair. Biomaterials play a crucial role in tissue engineering, providing temporary mechanical support and facilitating cellular processes to augment skin tissue regeneration.

Polycaprolactone for Hard Tissue Regeneration: Scaffold Design and In Vivo Implications

In the last thirty years, tissue engineering (TI) has emerged as an alternative method to regenerate tissues and organs and restore their function by implanting specific lineage cells, growth factors, or biomolecules functionalizing a matrix scaffold. Recently, several pathologies have led to bone loss or damage, such as malformations, bone resorption associated with benign or malignant tumors, periodontal disease, traumas, and others in which a discontinuity in tissue integrity is observed. Bone tissue is characterized by different stiffness, mechanical traction, and compression resistance as a function of the different compartments, which can influence susceptibility to injury or destruction. For this reason, research into repairing bone defects began several years ago to find a scaffold to improve bone regeneration. Different techniques can be used to manufacture 3D scaffolds for bone tissue regeneration based on optimizing reproducible scaffolds with a controlled hierarchical porous structure like the extracellular matrix of bone. Additionally, the scaffolds synthesized can facilitate the inclusion of bone or mesenchymal stem cells with growth factors that improve bone osteogenesis, recruiting new cells for the neighborhood to generate an optimal environment for tissue regeneration. In this review, current state-of-the-art scaffold manufacturing based on the use of polycaprolactone (PCL) as a biomaterial for bone tissue regeneration will be described by reporting relevant studies focusing on processing techniques, from traditional-i.e., freeze casting, thermally induced phase separation, gas foaming, solvent casting, and particle leaching-to more recent approaches, such as 3D additive manufacturing (i.e., 3D printing/bioprinting, electrofluid dynamics/electrospinning), as well as integrated techniques. As a function of the used technique, this work aims to offer a comprehensive overview of the benefits/limitations of PCL-based scaffolds in order to establish a relationship between scaffold composition, namely integration of other biomaterial phases' structural properties (i.e., pore morphology and mechanical properties) and in vivo response.

Biohybrid nano-platforms manifesting effective cancer therapy: Fabrication, characterization, challenges and clinical perspective

Nanotechnology-based delivery systems have brought a paradigm shift in the management of cancer. However, the main obstacles to nanocarrier-based delivery are their limited circulation duration, excessive immune clearance, inefficiency in interacting effectively in a biological context and overcoming biological barriers. This demands effective engineering of nanocarriers to achieve maximum efficacy. Nanocarriers can be maneuvered with biological components to acquire biological identity for further regulating their biodistribution and cell-to-cell cross-talk. Thus, the integration of synthetic and biological components to deliver therapeutic cargo is called a biohybrid delivery system. These delivery systems possess the advantage of synthetic nanocarriers, such as high drug loading, engineerable surface, reproducibility, adequate communication and immune evasion ability of biological constituents. The biohybrid delivery vectors offer an excellent opportunity to harness the synergistic properties of the best entities of the two worlds for improved therapeutic outputs. The major spotlights of this review are different biological components, synthetic counterparts of biohybrid nanocarriers, recent advances in hybridization techniques, and the design of biohybrid delivery systems for cancer therapy. Moreover, this review provides an overview of biohybrid systems with therapeutic and diagnostic applications. In a nutshell, this article summarizes the advantages and limitations of various biohybrid nano-platforms, their clinical potential and future directions for successful translation in cancer management.

Electrospun zeolitic imidazole framework-8 loaded silk fibroin/polycaprolactone nanofibrous scaffolds for biomedical application

The development of electrospun nanofibrous scaffolds (NFSs) have aroused much attraction in the field of biomedical engineering, due to their small fiber diameter, high specific surface area, and excellent extracellular matrix comparability. The main focus of this study is to design and fabricate novel zeolitic imidazole framework-8 (ZIF-8)-loaded silk fibrin/polycaprolactone (SF/PCL) nanofiber composite scaffolds by using the electrospinning strategy. Firstly, ZIF-8 was synthesized and characterized, which showed remarkable features in terms of shape, size, chemical and physical properties. Then, three different amounts of ZIF-8 were encapsulated into SF/PCL nanofibers during electrospinning, to investigate how the addition of ZIF-8 affected the morphology, and structure, as well as physical, mechanical, and biological properties of the nanofiber composite scaffolds. It was found that the addition of ZIF-8 didn't change the nanofibrous morphology of the composite scaffold, and no bead-like structure were found for the SF/PCL composite scaffolds loading with or without ZIF-8. The appropriate addition of ZIF-8 could significantly increase the mechanical properties of SF/PCL NFSs. The SF/PCL NFS containing 5% ZIF-8 showed high ultimate stress and initial modulus, which were 40.31 ± 2.31 MPa, and 569.19 ± 21.38 MPa, respectively. Furthermore, the MTT assay indicated that the pure SF/PCL scaffold and one with 1% ZIF-8 exhibited nearly identical cell compatibility toward human dermal fibroblast (HDF) cells, but some obvious cytotoxicity was observed with the increase of ZIF-8 content. However, the incorporation of ZIF-8 into SF/PCL NFSs was found to have excellent antibacterial rate against both E. coli and S. aureus. In all, the incorporation of 1% ZIF-8 could impart the SF/PCL NFS with balanced bio-function, making it a promising candidate for diverse biomedical applications such as tissue engineering and wound healing.

Claes K, Blondeel P, Monstrey S, Dorpe JV, Van Vlierberghe S. Photo-crosslinkable polyester microneedles as sustained drug release systems toward hypertrophic scar treatment

Burn injuries can result in a significant inflammatory response, often leading to hypertrophic scarring (HTS). Local drug therapies e.g. corticoid injections are advised to treat HTS, although they are invasive, operator-dependent, extremely painful and do not permit extended drug release. Polymer-based microneedle (MN) arrays can offer a viable alternative to standard care, while allowing for direct, painless dermal drug delivery with tailorable drug release profile. In the current study, we synthesized photo-crosslinkable, acrylate-endcapped urethane-based poly(ε-caprolactone) (AUP-PCL) toward the fabrication of MNs. Physico-chemical characterization (1H-NMR, evaluation of swelling, gel fraction) of the developed polymer was performed and confirmed successful acrylation of PCL-diol. Subsequently, AUP-PCL, and commercially available PCL-based microneedle arrays were fabricated for comparative evaluation of the constructs. Hydrocortisone was chosen as model drug. To enhance the drug release efficiency of the MNs, Brij®35, a nonionic surfactant was exploited. The thermal properties of the MNs were evaluated via differential scanning calorimetry. Compression testing of the arrays confirmed that the MNs stay intact upon applying a load of 7 N, which correlates to the standard dermal insertion force of MNs. The drug release profile of the arrays was evaluated, suggesting that the developed PCL arrays can offer efficient drug delivery for up to two days, while the AUP-PCL arrays can provide a release up to three weeks. Finally, the insertion of MN arrays into skin samples was performed, followed by histological analysis demonstrating the AUP-PCL MNs outperforming the PCL arrays upon providing pyramidical-shaped perforations through the epidermal layer of the skin.

A new application of avocado oil to enrich the biological activities of polycaprolactone membranes for tissue engineering

The metabolites synthesized by plants to protect themselves serves as natural antimicrobial agents used in biomaterials. In this study, avocado oil (AO), was incorporated as a plant source and natural antimicrobial agent into polycaprolactone (PCL) membranes. The effects of varying AO ratios (25, 50, and 100 wt%.-PCL@25AO, PCL@50AO, PCL@100AO) on PCL membrane morphology, chemical structure, wettability, antimicrobial activity, and cell viabilities were investigated. It was demonstrated that the AO acts as a pore-forming agent in solvent-casted membranes. Young's modulus of the membranes varied between 602.68 and 31.92 MPa and more flexible membranes were obtained with increasing AO content. Inhibition zones of AO were recorded between 7.86 and 13.97 mm against clinically relevant microbial strains including bacteria, yeast, and fungi. Antimicrobial activity of AO was retained in PCL membranes at all ratios. Resazurin assay indicated that PCL@25AO membranes were cytocompatible with mouse fibroblast cells (L929 cell line) on day 6 showing 72.4% cell viability with respect to neat PCL membranes. Viability results were supported by scanning electron microscopy images and DAPI staining. The overall results of this study highlight the potential of PCL@25AO membranes as a biomaterial with antimicrobial properties, cytocompatibility, and mechanical strength suitable for various biomedical applications.

Inhalable chitosan-coated nano-assemblies potentiate niclosamide for targeted abrogation of non-small-cell lung cancer through dual modulation of autophagy and apoptosis

Lung carcinoma, particularly non-small-cell lung cancer (NSCLC), accounts for a significant portion of cancer-related deaths, with a fatality rate of approximately 19 %. Niclosamide (NIC), originally an anthelmintic drug, has attracted attention for its potential in disrupting cancer cells through various intracellular signaling pathways. However, its effectiveness is hampered by limited solubility, reducing its bioavailability. This study investigates the efficacy of NIC against lung cancer using inhalable hybrid nano-assemblies with chitosan-functionalized Poly (ε-caprolactone) (PCL) as a carrier for pulmonary delivery. The evaluation encompasses various aspects such as aerodynamic and physicochemical properties, drug release kinetics, cellular uptake, biocompatibility, cell migration, autophagic flux, and apoptotic cell death in A549 lung cancer cells. Increasing NIC dosage correlates with enhanced inhibition of cell proliferation, showing a dose-dependent profile (approximately 75 % inhibition efficiency at 20 μg/mL of NIC). Optimization of inhaled dosage and efficacy is conducted in a murine model of NNK-induced tumor-bearing lung cancer. Following inhalation, NIC-CS-PCL-NA demonstrates significant lung deposition, retention, and metabolic stability. Inhalable nano-assemblies promote autophagy flux and induce apoptotic cell death. Preclinical trials reveal substantial tumor regression with minimal adverse effects, underscoring the potential of inhalable NIC-based nano-formulation as a potent therapeutic approach for NSCLC, offering effective tumor targeting and killing capabilities.

Electrohydrodynamic Direct-Writing Micro/Nanofibrous Architectures: Principle, Materials, and Biomedical Applications

Electrohydrodynamic (EHD) direct-writing has recently gained attention as a highly promising additive manufacturing strategy for fabricating intricate micro/nanoscale architectures. This technique is particularly well-suited for mimicking the extracellular matrix (ECM) present in biological tissue, which serves a vital function in facilitating cell colonization, migration, and growth. The integration of EHD direct-writing with other techniques has been employed to enhance the biological performance of scaffolds, and significant advancements have been made in the development of tailored scaffold architectures and constituents to meet the specific requirements of various biomedical applications. Here, a comprehensive overview of EHD direct-writing is provided, including its underlying principles, demonstrated materials systems, and biomedical applications. A brief chronology of EHD direct-writing is provided, along with an examination of the observed phenomena that occur during the printing process. The impact of biomaterial selection and architectural topographic cues on biological performance is also highlighted. Finally, the major limitations associated with EHD direct-writing are discussed.

Peptide-Coated Polycaprolactone-Benzalkonium Chloride Nanocapsules for Targeted Drug Delivery to the Pancreatic β-Cell

Targeting current therapies to treat or prevent the loss of pancreatic islet β-cells in Type 1 Diabetes (T1D) may provide improved efficacy and reduce off-target effects. Current efforts to target the β-cell are limited by a lack of β-cell-specific targets and the inability to test multiple targeting moieties with the same delivery vehicle. Here, we fabricate a tailorable polycaprolactone nanocapsule (NC) in which multiple different targeting peptides can be interchangeably attached for β-cell-specific delivery. Incorporation of a cationic surfactant in the NC shell allows for the attachment of Exendin-4 and an antibody for ectonucleoside triphosphate diphosphohydrolase 3 (ENTPD3) for β-cell-specific targeting. The average NC size ranges from 250 to 300 nm with a polydispersity index under 0.2. The NCs are nontoxic, stable in media culture, and can be lyophilized and reconstituted. NCs coated with a targeting peptide were taken up by human cadaveric islet β-cells and human stem cell-derived β-like cells (sBC) in vitro with a high level of specificity. Furthermore, NCs successfully delivered both hydrophobic and hydrophilic cargo to human β-cells. Additionally, Exendin-4-coated NCs were stable and targeted the mouse pancreatic islet β-cell in vivo. Overall, our tailorable NCs have the potential to improve cell-targeted drug delivery and can be utilized as a screening platform to test the efficacy of cell-targeting peptides.

Antimicrobial cyclodextrin-assisted electrospun fibers loaded with carvacrol, citronellol and cinnamic acid for wound healing

This work aimed to explore an alternative to the use of antibiotics for prevention and treatment of wounds infection caused by two common bacterial pathogens Staphylococcus aureus and Pseudomonas aeruginosa. For this purpose, three different essential oil components (EOCs), namely carvacrol, citronellol and cinnamic acid, were loaded into electrospun fibers of poly-ε-caprolactone (PCL) aided by alpha-cyclodextrin (αCD) and hydroxypropyl-β-cyclodextrin (HPβCD). Electrospun-fibers prepared with each EOC and their mixtures were screened for antimicrobial capability and characterized regarding morphological, mechanical, thermal, surface polarity, antibiofilm and antioxidant properties. αCD formed poly(pseudo)rotaxanes with PCL and weakly interacted with EOCs, while HPβCD facilitated EOC encapsulation and formation of homogeneous fibers (500-1000 nm diameter) without beads. PCL/HPβCD fibers with high concentration of EOCs (mainly carvacrol and cinnamic acid) showed strong antibiofilm (>3 log CFU reduction) and antioxidant activity (10-50% DPPH scavenging effects). Different performances were recorded for the EOCs and their mixtures; cinnamic acid migrated to fiber surface and was released faster. Fibers biocompatibility was verified using hemolysis tests and in ovo tissue integration and angiogenesis assays. Overall, HPβCD facilitates complete release of EOCs from the fibers to the aqueous medium, being an environment-friendly and cost-effective strategy for the treatment of infected wounds.

Biologicals and Biomaterials for Corneal Regeneration and Vision Restoration in Limbal Stem Cell Deficiency

The mammalian cornea is decorated with stem cells bestowed with the life-long task of renewing the epithelium, provided they remain healthy, functional, and in sufficient numbers. If not, a debilitating disease known as limbal stem cell deficiency (LSCD) can develop causing blindness. Decades after the first stem cell (SC) therapy is devised to treat this condition, patients continue to suffer unacceptable failures. During this time, improvements to therapeutics have included identifying better markers to isolate robust SC populations and nurturing them on crudely modified biological or biomaterial scaffolds including human amniotic membrane, fibrin, and contact lenses, prior to their delivery. Researchers are now gathering information about the biomolecular and biomechanical properties of the corneal SC niche to decipher what biological and/or synthetic materials can be incorporated into these carriers. Advances in biomedical engineering including electrospinning and 3D bioprinting with surface functionalization and micropatterning, and self-assembly models, have generated a wealth of biocompatible, biodegradable, integrating scaffolds to choose from, some of which are being tested for their SC delivery capacity in the hope of improving clinical outcomes for patients with LSCD.

3D printed polycaprolactone/gelatin/ordered mesoporous calcium magnesium silicate nanocomposite scaffold for bone tissue regeneration

Tissue engineering scaffolds are three-dimensional structures that provide an appropriate environment for cellular attachment, proliferation, and differentiation. Depending on their specific purpose, these scaffolds must possess distinct features, including appropriate mechanical properties, porosity, desired degradation rate, and cell compatibility. This investigation aimed to fabricate a new nanocomposite scaffold using a 3D printing technique composed of poly(ε-caprolactone) (PCL)/Gelatin (GEL)/ordered mesoporous calcium-magnesium silicate (om-CMS) particles. Different weight ratios of om-CMS were added and optimized, and a series of scaffolds were constructed for comparison purposes, including PCL 50%/Gel 50%, PCL 50%/Gel 45%/om-CMS%5, and PCL 50%/Gel 40%/om-CMS%10. The optimized weight ratio of om-CMS was 10% without leaving behind negative effects on the filaments' structure. The scaffolds' physical and chemical properties were assessed using various techniques, and their degradation rate, bioactivity potential, cell viability, attachment, and ALP activity were evaluated in vitro. The results demonstrated that the PCL 50%/Gel 40%/om-CMS10% scaffold had promising potential for further studies in bone tissue regeneration.

Osteogenic potentials in canine mesenchymal stem cells: unraveling the efficacy of polycaprolactone/hydroxyapatite scaffolds in veterinary bone regeneration

BACKGROUND

The integration of stem cells, signaling molecules, and biomaterial scaffolds is fundamental for the successful engineering of functional bone tissue. Currently, the development of composite scaffolds has emerged as an attractive approach to meet the criteria of ideal scaffolds utilized in bone tissue engineering (BTE) for facilitating bone regeneration in bone defects. Recently, the incorporation of polycaprolactone (PCL) with hydroxyapatite (HA) has been developed as one of the suitable substitutes for BTE applications owing to their promising osteogenic properties. In this study, a three-dimensional (3D) scaffold composed of PCL integrated with HA (PCL/HA) was prepared and assessed for its ability to support osteogenesis in vitro. Furthermore, this scaffold was evaluated explicitly for its efficacy in promoting the proliferation and osteogenic differentiation of canine bone marrow-derived mesenchymal stem cells (cBM-MSCs) to fill the knowledge gap regarding the use of composite scaffolds for BTE in the veterinary orthopedics field.

RESULTS

Our findings indicate that the PCL/HA scaffolds substantially supported the proliferation of cBM-MSCs. Notably, the group subjected to osteogenic induction exhibited a markedly upregulated expression of the osteogenic gene osterix (OSX) compared to the control group. Additionally, the construction of 3D scaffold constructs with differentiated cells and an extracellular matrix (ECM) was successfully imaged using scanning electron microscopy. Elemental analysis using a scanning electron microscope coupled with energy-dispersive X-ray spectroscopy confirmed that these constructs possessed the mineral content of bone-like compositions, particularly the presence of calcium and phosphorus.

CONCLUSIONS

This research highlights the synergistic potential of PCL/HA scaffolds in concert with cBM-MSCs, presenting a multidisciplinary approach to scaffold fabrication that effectively regulates cell proliferation and osteogenic differentiation. Future in vivo studies focusing on the repair and regeneration of bone defects are warranted to further explore the regenerative capacity of these constructs, with the ultimate goal of assessing their potential in veterinary clinical applications.

Controlling Mechanical Properties of Medical-Grade Scaffolds through Electrospinning Parameter Selection

Electrospinning (ES) is a versatile process mode for creating fibrous materials with various structures that have broad applications ranging from regenerative medicine to tissue engineering and surgical mesh implants. The recent commercialization of this technology for implant use has driven the use of resorbable electrospun products. Resorbable electrospun meshes offer great promise as temporary implants that can utilize the layer upon layer method of additive manufacturing to incorporate porosity as a function of process parameters into a scaffold structure. The interconnected porosity and feature size known to ES have previously been observed to hold great potential for simulating the natural cellular environment of soft tissue. This microstructure, proper degradation kinetics, and mechanical properties combine to provide the design basis for artificial tissue structures that could aid in not only wound healing but also true tissue engineering and regenerative medicine. While current advancement in the field is understood to be limited by material properties, the importance of optimizing mechanical properties with currently available materials should not be overlooked. This work investigated the process parameter effects and interactions that control the structure-property relationship for a range of medical-grade aliphatic polyester materials with a range of intrinsic properties. An ε-caprolactone homopolymer (PCL), l-lactide homopolymer (PLLA), and Lactoflex, a copolymer with intermediate properties relative to the homopolymers, were characterized before, during, and after the additive manufacturing process. The interacting effects of process parameters, distance to collector, and dispensing rate were shown to produce variable-density, nonwoven scaffold structures. The resorbable mesh scaffolds of PLLA, PCL, and Lactoflex demonstrated a broad range of mechanical properties (approximately 1-10 MPa ultimate tensile strength and 5-390 MPa tensile modulus). Postprocessing of scaffolds demonstrated removal of solvents and preservation of micrometer-sized features. Resorbable polymers and electrospinning can produce scaffold materials with excellent features and offer tremendous potential in the field of implantable resorbable devices.

Synthesis, Characterization and Application of Advanced Antimicrobial Electrospun Polymers

The aim of this work was to synthesize, characterize and apply advanced antimicrobial biocompatible electrospun polymers suitable for medical implants for surgical repairs. Injuries to the musculoskeletal system often necessitate surgical repair, but current treatments can still lead to high failure rates, such as 40% for the repair of rotator cuff tears. Therefore, there is an urgent need for the development of new biocompatible materials that can effectively support the repair of damaged tissues. Additionally, infections acquired during hospitalization, particularly those caused by antibiotic-resistant bacteria, result in more fatalities than AIDS, tuberculosis, and viral hepatitis combined. This underscores the critical necessity for the advancement of antimicrobial implants with specialized coatings capable of combating Methicillin-resistant Staphylococcus aureus (MRSA) and Methicillin-sensitive Staphylococcus aureus (MSSA), two strains notoriously known for their antibiotic resistance. Therefore, we developed an antimicrobial coating incorporating nanoparticle mixtures using the sol-gel process and applied it to electrospun polycaprolactone (PCL) filaments, followed by thorough characterization by using spectroscopic (FTIR, Raman, NMR) microscopic (SEM and SEM-EDX), and tensile test. The results have shown that the integration of electro-spinning technology for yarn production, coupled with surface modification techniques, holds significant potential for creating antimicrobial materials suitable for medical implants for surgical repairs.

Facile roll-to-roll production of nanoporous fiber coatings for advanced wound care sutures

Theranostic sutures are derived from innovative ideas to enhance wound healing results by adding wound diagnostics and therapeutics to typical sutures by functionalizing them with additional materials. Here, we present a new direct electrospinning method for the fast, continuous, inexpensive, and high-throughput production of versatile nanofibrous-coated suture threads, with precise control over various essential microstructural and physical characteristics. The thickness of the coating layer and the alignment of nanofibers with the thread's direction can be adjusted by the user by varying the spooling speed and the displacement between the spinneret needle and thread. To show the flexibility of our method for a range of different materials selected, gelatin, polycaprolactone, silk fibroin, and PEDOT:PSS (poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate)) were the resultant nanofibers characterized by scanning electron microscopy (SEM) imaging and conductivity tests. In a series of in vitro and ex vivo tests (pig skin), sutures were successfully tested for their flexibility and mechanical properties when used as weaving and knotting sutures, and their biocompatibility with a keratinocyte cell line. For temperature-based drug-releasing tests, two fluorescent molecules as drug models with high and low molecular weight, namely fluorescein isothiocyanate-dextran (20 kDa) and rhodamine B (470 Da), were used, and their steady release with incremental increase of temperature to 37 °C over 120 min was seen, which is appropriate for bacterial treatment drugs. Given the advantages of the presented technique, it seems to have promising potential to be used in future medical applications for wound closure and bacterial infection treatment via a temperature-triggered drug release strategy.

Fabrication of oxygen-releasing dextran microgels by droplet-based microfluidic method

In the tissue engineering field, the supply of oxygen to three-dimensional (3D) tissues is an important aspect to avoid necrosis due to hypoxia. Although oxygen-releasing bulk materials containing calcium peroxide (CaO2, CP) have attracted much attention, micrometer-sized oxygen-releasing soft materials would be advantageous because of their highly controllable structures, which can be applied for cell scaffolds, injectable materials, and bioink components in 3D bioprinting. In this study, oxygen-releasing microgels were fabricated via a droplet-based microfluidic system. Homogeneous, monodisperse and stable oxygen-releasing microgels were obtained by photo-crosslinking of droplets composed of biocompatible dextran modified with methacrylate groups and CP nanoparticles as an oxygen source. We also used our microfluidic system for the in situ amorphous calcium carbonate (CaCO3, ACC) formation on the surface of CP nanoparticles to achieve the controlled release of oxygen from the microgel. Oxygen release from an ACC-CP microgel in a neutral cell culture medium was suppressed because incorporation of CP in the ACC suppressed the reaction with water. Strikingly, stimuli to dissolve ACC such as a weak acidic conditions triggered the oxygen release from microgels loaded with ACC-CP, as the dissolution of CaCO3 allows CP to react. Taken together, applications of this new class of biomaterials for tissue engineering are greatly anticipated. In addition, the developed microfluidic system can be used for a variety of oxygen-releasing microgels by changing the substrates of the hydrogel network.

Peptide Coated Polycaprolactone-Benzalkonium Chloride Nanocapsules for Targeted Drug Delivery to the Pancreatic β-Cell

Targeting of current therapies to treat or prevent loss of pancreatic islet β-cells in Type 1 Diabetes (T1D) may provide improved efficacy and reduce off target effects. Current efforts to target the β-cell are limited by a lack of β-cell specific targets and the inability to test multiple targeting moieties with the same delivery vehicle. Here we fabricate a novel tailorable polycaprolactone nanocapsule (NC) where multiple different targeting peptides can be interchangeably attached for β-cell specific delivery. Incorporation of a cationic surfactant in the NC shell allows for the attachment of Exendin-4 and an antibody for ectonucleoside triphosphate diphosphohydrolase 3 (ENTPD3) for β-cell specific targeting. The average NC size ranges from 250-300nm with a polydispersity index under 0.2. The NCs are non-toxic, stable in media culture, and can be lyophilized and reconstituted. NCs coated with targeting peptide were taken up by human cadaveric islet β-cells and human stem cell-derived β-like cells (sBC) in vitro with a high level of specificity. Furthermore, NCs successfully delivered both hydrophobic and hydrophilic cargo to human β-cells. Finally, Exendin-4 coated NCs were stable and targeted the mouse pancreatic islet β-cell in vivo . Our unique NC design allows for the interchangeable coating of targeting peptides for future screening of targets with improved cell specificity. The ability to target and deliver thera-peutics to human pancreatic β-cells opens avenues for improved therapies and treatments to help the delay onset, prevent, or reverse T1D.

Protective Role of Nanoceria-Infused Nanofibrous Scaffold toward Bone Tissue Regeneration with Senescent Cells

The presence of oxidative stress in bone defects leads to delayed regeneration, especially in the aged population and patients receiving cancer treatment. This delay is attributed to the increased levels of reactive oxygen species (ROS) in these populations due to the accumulation of senescent cells. Tissue-engineered scaffolds are emerging as an alternative method to treat bone defects. In this study, we engineered tissue scaffolds tailored to modulate the adverse effects of oxidative stress and promote bone regeneration. We used polycaprolactone to fabricate nanofibrous mats by using electrospinning. We exploited the ROS-scavenging properties of cerium oxide nanoparticles to alleviate the high oxidative stress microenvironment caused by the presence of senescent cells. We characterized the nanofibers for their physical and mechanical properties and utilized an ionization-radiation-based model to induce senescence in bone cells. We demonstrate that the presence of ceria can modulate ROS levels, thereby reducing the level of senescence and promoting osteogenesis. Overall, this study demonstrates that ceria-infused nanofibrous scaffolds can be used for augmenting the osteogenic activity of senescent progenitor cells, which has important implications for engineering bone tissue scaffolds for patients with low regeneration capabilities.

A Polycaprolactone-Capped ZnO Quantum Dots-Based Fluorometric Sensor for the Detection of Fe3+ Ions in Seawater

Fe3+ ion plays a very active role in life, agriculture, and industry. Human health and the environment are seriously affected by the abnormal presence or excess of this cation. Therefore, the development of a fast, reliable, sensitive, and simple fluorescent probe to detect this cation is crucial. In the present paper, polycaprolactone-capped zinc oxide quantum dots were prepared for the determination of Fe3+ ions. The proposed fluorescent chemosensor exhibited a fluorometric and strong quenching effect toward Fe3+ ions at two wavelengths (303 and 602 nm). The limit of detection (LOD) was calculated as 0.410, and 0.333µM at the mentioned wavelengths. Also, the binding stoichiometric ratio was calculated as 1:1 by Job's plot. The findings indicated that the PCL@ZnO colorimetric chemosensor could be successfully applied with reliable, and good accuracy for the detection of Fe3+ ions in real seawater samples.

Multi-variate multi-objective optimization of production conditions for electro-spun skin scaffold using RSM and investigation of gamma irradiation effects on the properties of the optimized sample

Developing electro-spun scaffolds with ideal mechanical properties for skin purposes can profit from using the Response Surface Methodology technique to define and optimize the outcome quality and required sterilization for use in vivo. This study investigated the effects of four main independent electrospinning variables for polycaprolactone nanofibers scaffold using multi-variable and multi-objective optimization. It was done to determine significant parameters on responses and find optimal conditions to reach the preferred properties. Young's modulus, elongation-at-break, and tensile strength were the responses. After obtaining appropriate models, the impact share of variables on the responses was determined using Sobol sensitivity analysis. The results showed that flow rate is the most significant parameter of elastic modulus and tensile strength responses, with 76.45 % and 41.27 % impact shares, respectively. The polymer concentration is the following significant parameter on elongation at break, tensile strength and, Young's modulus responses with 64.35 %, 39.485 and, 14.28 % impact share, respectively. Based on the optimized results, a skin scaffold with desired mechanical properties was achieved (under solution concentration of 10 % w/v, flow rate of 2 mL/h, nuzzle-collector distance of 15 cm, and applied voltage of 20 kV). Then it was sterilized with gamma radiation of various doses (25, 40, and 55 kGy) to use in vivo. The SEM analysis indicated no significant change in fibrous morphology due to gamma irradiation at any dosage. FTIR analysis demonstrated the breakup of ester bonds due to gamma irradiation. For samples irradiated by 25 kGy, the crystallinity percentage decreased and chains crosslinking without losing the mechanical stability was dominant. The studies demonstrated that 25 kGy of gamma irradiation could improve the mechanical properties of the optimized PCL skin scaffold, which is very promising for wound healing.

Polymers in 3D printing of external maxillofacial prostheses and in their retention systems

Maxillofacial defects, arising from trauma, oncological disease or congenital abnormalities, detrimentally affect daily life. Prosthetic repair offers the aesthetic and functional reconstruction with the help of materials mimicking natural tissues. 3D polymer printing enables the design of patient-specific prostheses with high structural complexity, as well as rapid and low-cost fabrication on-demand. However, 3D printing for prosthetics is still in the early stage of development and faces various challenges for widespread use. This is because the most suitable polymers for maxillofacial restoration are soft materials that do not have the required printability, mechanical strength of the printed parts, as well as functionality. This review focuses on the challenges and opportunities of 3D printing techniques for production of polymer maxillofacial prostheses using computer-aided design and modeling software. Review discusses the widely used polymers, as well as their blends and composites, which meet the most important assessment criteria, such as the physicochemical, biological, aesthetic properties and processability in 3D printing. In addition, strategies for improving the polymer properties, such as their printability, mechanical strength, and their ability to print multimaterial and architectural structures are highlighted. The current state of the prosthetic retention system is presented with a focus on actively used polymer adhesives and the recently implemented prosthesis-supporting osseointegrated implants, with an emphasis on their creation from 3D-printed polymers. The successful prosthetics is discussed in terms of the specificity of polymer materials at the restoration site. The approaches and technological prospects are also explored through the examples of the nasal, auricle and ocular prostheses, ranging from prototypes to end-use products.

Biomaterials-Based Strategies to Enhance Angiogenesis in Diabetic Wound Healing

Amidst the present healthcare issues, diabetes is unique as an emerging class of affliction with chronicity in a majority of the population. To check and control its effects, there have been huge turnover and constant development of management strategies, and though a bigger part of the health care area is involved in achieving its control and the related issues such as the effect of diabetes on wound healing and care and many of the works have reached certain successful outcomes, still there is a huge lack in managing it, with maximum effect yet to be attained. Studying pathophysiology and involvement of various treatment options, such as tissue engineering, application of hydrogels, drug delivery methods, and enhancing angiogenesis, are at constantly developing stages either direct or indirect. In this review, we have gathered a wide field of information and different new therapeutic methods and targets for the scientific community, paving the way toward more settled ideas and research advances to cure diabetic wounds and manage their outcomes.

Recent Advances in the Use of Stem Cells in Tissue Engineering and Adjunct Therapies for Tendon Reconstruction and Future Perspectives

Due to their function, tendons are exposed to acute injuries. This type of damage to the musculoskeletal system represents a challenge for clinicians when natural regeneration and treatment methods do not produce the expected results. Currently, treatment is long and associated with long-term complications. In this review, we discuss the use of stem cells in the treatment of tendons, including how to induce appropriate cell differentiation based on gene therapy, growth factors, tissue engineering, proteins involved in regenerative process, drugs and three-dimensional (3D) structures. A multidirectional approach as well as the incorporation of novel components of the therapy will improve the techniques used and benefit patients with tendon injuries in the future.

Light-responsive polymeric nanoparticles for retinal drug delivery: design cues, challenges and future perspectives

A multitude of sight-threatening retinal diseases, affecting hundreds of millions around the globe, lack effective pharmacological treatments due to ocular barriers and common drug delivery limitations. Polymeric nanoparticles (PNPs) are versatile drug carriers with sustained drug release profiles and tunable physicochemical properties which have been explored for ocular drug delivery to both anterior and posterior ocular tissues. PNPs can incorporate a wide range of drugs and overcome the challenges of conventional retinal drug delivery. Moreover, PNPs can be engineered to respond to specific stimuli such as ultraviolet, visible, or near-infrared light, and allow precise spatiotemporal control of the drug release, enabling tailored treatment regimens and reducing the number of required administrations. The objective of this study is to emphasize the therapeutic potential of light-triggered drug-loaded polymeric nanoparticles to treat retinal diseases through an exploration of ocular pathologies, challenges in drug delivery, current production methodologies and recent applications. Despite challenges, light-responsive PNPs hold the promise of substantially enhancing the treatment landscape for ocular diseases, aiming for an improved quality of life for patients.

Depolymerization within a Circular Plastics System

The societal importance of plastics contrasts with the carelessness with which they are disposed. Their superlative properties lead to economic and environmental efficiency, but the linearity of plastics puts the climate, human health, and global ecosystems at risk. Recycling is fundamental to transitioning this linear model into a more sustainable, circular economy. Among recycling technologies, chemical depolymerization offers a route to virgin quality recycled plastics, especially when valorizing complex waste streams poorly served by mechanical methods. However, chemical depolymerization exists in a complex and interlinked system of end-of-life fates, with the complementarity of each approach key to environmental, economic, and societal sustainability. This review explores the recent progress made into the depolymerization of five commercial polymers: poly(ethylene terephthalate), polycarbonates, polyamides, aliphatic polyesters, and polyurethanes. Attention is paid not only to the catalytic technologies used to enhance depolymerization efficiencies but also to the interrelationship with other recycling technologies and to the systemic constraints imposed by a global economy. Novel polymers, designed for chemical depolymerization, are also concisely reviewed in terms of their underlying chemistry and potential for integration with current plastic systems.

A multistep (semi)-continuous biocatalytic setup for the production of polycaprolactone

Biocatalysis has gained increasing importance as an eco-friendly alternative for the production of bulk and fine chemicals. Within this paradigm, Baeyer Villiger monoxygenases (BVMOs) serve as enzymatic catalysts that provide a safe and sustainable route to the conventional synthesis of lactones, such as caprolactone, which is employed for the production of polycaprolactone (PCL), a biocompatible polymer for medicinal applications. In this work, we present a three-step, semi-continuous production of PCL using an entirely biocatalytic process, highlighting the merits of continuous manufacturing for enhancing biocatalysis. First, caprolactone is produced in batch from cyclohexanol using a coenzymatic cascade involving an alcohol dehydrogenase (ADH) and BVMO. Different process parameters and aeration modes were explored to optimize the cascade's productivity. Secondly, the continuous extraction of caprolactone into an organic solvent, needed for the polymerization step, was optimized. 3D-printed mixers were applied to enhance the mass transfer between the organic and the aqueous phases. Lastly, we investigated the ring-opening polymerization of caprolactone to PCL catalyzed by Candida antarctica lipase B (CAL-B), with a focus on eco-friendly solvents like cyclopentyl-methyl-ether (CPME). Space-time-yields up to 58.5 g L-1 h-1 were achieved with our overall setup. By optimizing the individual process steps, we present an efficient and sustainable pathway for PCL production.

Development of a multi-component gastroretentive expandable drug delivery system (GREDDS) for personalized administration of metformin

OBJECTIVES

Efficacy and compliance of type II diabetes treatment would greatly benefit from dosage forms providing controlled release of metformin in the upper gastrointestinal tract. In this respect, the feasibility of a new system ensuring stomach-retention and personalized release of this drug at its absorption window for multiple days was investigated.

METHODS

The system proposed comprised of a drug-containing core and a viscoelastic umbrella-like skeleton, which were manufactured by melt-casting and 3D printing. Prototypes, alone or upon assembly and insertion into commercially-available capsules, were characterized for key parameters: thermo-mechanical properties, accelerated stability, degradation, drug release, deployment performance, and resistance to simulated gastric contractions.

RESULTS

Each part of the system was successfully manufactured using purposely-selected materials and the performance of final prototypes matched the desired one. This included: i) easy folding of the skeleton against the core in the collapsed administered shape, ii) rapid recovery of the cumbersome configuration at the target site, even upon storage, and iii) prolonged release of metformin.

CONCLUSIONS

Composition, geometry, and performance of the system developed in this work were deemed acceptable for stomach-retention and prolonged as well as customizable release of metformin in its absorption window, laying promising bases for further development steps.

Effect of Gelatin Coating and GO Incorporation on the Properties and Degradability of Electrospun PCL Scaffolds for Bone Tissue Regeneration

Polymer-based nanocomposites such as polycaprolactone/graphene oxide (PCL/GO) have emerged as alternatives for bone tissue engineering (BTE) applications. The objective of this research was to investigate the impact of a gelatin (Gt) coating on the degradability and different properties of PCL nanofibrous scaffolds fabricated by an electrospinning technique with 1 and 2 wt% GO. Uniform PCL/GO fibers were obtained with a beadless structure and rough surface. PCL/GO scaffolds exhibited an increase in their crystallization temperature (Tc), attributed to GO, which acted as a nucleation agent. Young's modulus increased by 32 and 63% for the incorporation of 1 and 2 wt% GO, respectively, in comparison with neat PCL. A homogeneous Gt coating was further applied to these fibers, with incorporations as high as 24.7 wt%. The introduction of the Gt coating improved the hydrophilicity and degradability of the scaffolds. Bioactivity analysis revealed that the hydroxyapatite crystals were deposited on the Gt-coated scaffolds, which made them different from their uncoated counterparts. Our results showed the synergic effect of Gt and GO in enhancing the multifunctionality of the PCL, in particular the degradability rate, bioactivity, and cell adhesion and proliferation of hGMSC cells, making it an interesting biomaterial for BTE.

Prolonged and Controllable Release of Doxorubicin Hydrochloride from the Composite Electrospun Poly(ε-Caprolactone)/Polyvinylpyrrolidone Scaffolds

Burst release, typical for the drug-loaded electrospun poly(ε-caprolactone) (PCL) scaffolds is unfavorable in case of cytostatics due to the toxic levels reached during the initial implantation period. In the present short communication, we report an unexpected ability of the composite scaffolds made of PCL and water-soluble polyvinylpyrrolidone (PVP) to provide long-term release of widely used anti-cancer drug doxorubicin hydrochloride (DOX-HCl). That effect was observed for electrospun DOX-HCl-loaded composite scaffolds based on PCL and PVP with various mass ratios (100/0, 95/5, 90/10, 75/25 and 50/50). After the morphology and water contact angle studies, it was concluded that PVP content has no effect on the average fiber diameter, while PVP content higher 10 wt. % changes the hydrophobic character of the scaffolds surface (water contact angle of 123.9 ± 3.5°) to superhydrophilic (water contact angle of 0°). Despite the dramatic change in water wettability, by high performance liquid chromatography (HPLC), it was revealed that the PVP content in the scaffolds reduces the DOX-HCl release rate under short (first hours) and long-term (during 1 month) exposure to phosphate buffer saline (PBS). These results are in good agreement with in vitro studies, in which the viability of HeLa cervical cancer cells was higher after 24 h of culture with scaffolds with high PVP content.

Epidural Administration of Curcumin-Loaded Polycaprolactone/Gelatin Electrospun Nanofibers for Extended Analgesia After Laminectomy in Rats

Several clinical studies have reported the analgesic effect of curcumin (Curc) in various situations such as rheumatoid arthritis, osteoarthritis, and postsurgical pain. Therefore, in this work, Curc-loaded electrospun nanofibers (NFs) are designed to evaluate their sustained release on analgesic effect duration in rats after epidural placement via repeated formalin and tail-flick tests. The Curc-loaded polycaprolactone/gelatin NFs (Curc-PCL/GEL NFs) are prepared through an electrospinning technique and introduced to the rat's epidural space after laminectomy. The physicochemical and morphology features of the prepared Curc-PCL/GEL NFs were characterized via FE-SEM, FTIR, and degradation assay. The in vitro and in vivo concentrations of Curc were measured to evaluate the analgesic efficacy of the drug-loaded NFs. Rat nociceptive responses are investigated through repeated formalin and tail-flick tests for 5 weeks after the placement of NFs. Curc had a sustained release from the NFs for 5 weeks, and its local pharmaceutical concentrations were much greater than plasma concentrations. Rat's pain scores in both early and late phases of the formalin test were remarkably decreased in the experimental period. Rat's tail-flick latency was remarkably enhanced and remained constant for up to 4 weeks. Our findings show that the Curc-PCL/GEL NFs can supply controlled release of Curc to induce extended analgesia after laminectomy.

Micro/nano-patterns for enhancing differentiation of human neural stem cells and fabrication of nerve conduits via soft lithography and 3D printing

Topographical cues on materials can manipulate cellular fate, particularly for neural cells that respond well to such cues. Utilizing biomaterial surfaces with topographical features can effectively influence neuronal differentiation and promote neurite outgrowth. This is crucial for improving the regeneration of damaged neural tissue after injury. Here, we utilized groove patterns to create neural conduits that promote neural differentiation and axonal growth. We investigated the differentiation of human neural stem cells (NSCs) on silicon dioxide groove patterns with varying height-to-width/spacing ratios. We hypothesize that NSCs can sense the microgrooves with nanoscale depth on different aspect ratio substrates and exhibit different morphologies and differentiation fate. A comprehensive approach was employed, analyzing cell morphology, neurite length, and cell-specific markers. These aspects provided insights into the behavior of the investigated NSCs and their response to the topographical cues. Three groove-pattern models were designed with varying height-to-width/spacing ratios of 80, 42, and 30 for groove pattern widths of 1 μm, 5 μm, and 10 μm and nanoheights of 80 nm, 210 nm, and 280 nm. Smaller groove patterns led to longer neurites and more effective differentiation towards neurons, whereas larger patterns promoted multidimensional differentiation towards both neurons and glia. We transferred these cues onto patterned polycaprolactone (PCL) and PCL-graphene oxide (PCL-GO) composite 'stamps' using simple soft lithography and reproducible extrusion 3D printing methods. The patterned scaffolds elicited a response from NSCs comparable to that of silicon dioxide groove patterns. The smallest pattern stimulated the highest neurite outgrowth, while the middle-sized grooves of PCL-GO induced effective synaptogenesis. We demonstrated the potential for such structures to be wrapped into tubes and used as grafts for peripheral nerve regeneration. Grooved PCL and PCL-GO conduits could be a promising alternative to nerve grafting.

Development of ibuprofen-loaded electrospun materials suitable for surgical implantation in peripheral nerve injury

The development of nerve wraps for use in the repair of peripheral nerves has shown promise over recent years. A pharmacological effect to improve regeneration may be achieved by loading such materials with therapeutic agents, for example ibuprofen, a non-steroidal anti-inflammatory drug with neuroregenerative properties. In this study, four commercially available polymers (polylactic acid (PLA), polycaprolactone (PCL) and two co-polymers containing different ratios of PLA to PCL) were used to fabricate ibuprofen-loaded nerve wraps using blend electrospinning. In vitro surgical handling experiments identified a formulation containing a PLA/PCL 70/30 molar ratio co-polymer as the most suitable for in vivo implantation. In a rat model, ibuprofen released from electrospun materials significantly improved the rate of axonal growth and sensory recovery over a 21-day recovery period following a sciatic nerve crush. Furthermore, RT-qPCR analysis of nerve segments revealed that the anti-inflammatory and neurotrophic effects of ibuprofen may still be observed 21 days after implantation. This suggests that the formulation developed in this work could have potential to improve nerve regeneration in vivo.

Antibacterial Effect and Therapy of Chronic Skin Defects Using the Composite Bioscaffold Polycaprolactone/GelitaSpon/Povidone-Iodine in Domestic Dogs

Chronic wounds and the failure of conventional treatment are relatively common in veterinary medicine. Recently, there has been a growing interest in alternative therapeutic approaches and the utilization of biodegradable materials. Their potential application in wound therapy may offer a novel and more suitable option compared to conventional treatment methods. Biodegradable materials can be classified into two main categories: natural, synthetic, and a combination of both, which have the potential to have synergistically enhanced properties. In this study, four domestic dogs with clinical symptoms of chronic wounds were enrolled. These wounds underwent treatment utilizing a novel biodegradable composite material composed of gelatin sponge combined with two electrospun layers of polycaprolactone (PCL) along with polyvinylpyrrolidone (PVP) fibers containing povidone-iodine complex (PVP-I). The initial phase of the study was dedicated to evaluating the antibacterial properties of iodine against Staphylococcus aureus and Escherichia coli. On average, wound healing in domestic dogs took 22 days from the initial treatment, and iodine concentrations demonstrated a significant antibacterial effect against Escherichia coli and Staphylococcus aureus. Based on the favorable outcomes observed in wound management, we believe that the utilization of a blend of natural and synthetic biodegradable materials holds promise as an effective wound therapy option.

Ecotoxicity studies of two atrazine nanoformulations: From the evaluation of stability in media to the effects on aquatic organisms

In the field of agriculture, nanopesticides have been developed as an alternative to the conventional pesticides, being more efficient for pest control. However, before their widespread application it is essential to evaluate their safe application and no environmental impacts. In this paper, we evaluated the toxicological effects of two kinds of atrazine nanoformulations (ATZ NPs) in different biological models (Raphidocelis subcapitata, Danio rerio, Lemna minor, Artemia salina, Lactuca sativa and Daphnia magna) and compared the results with nanoparticle stability over time and the presence of natural organic matter (NOM). The systems showed different characteristics for Zein (ATZ NPZ) (184 ± 2 nm with a PDI of 0.28 ± 0.04 and zeta potential of (30.4 ± 0.05 mV) and poly(epsilon-caprolactone (ATZ PCL) (192 ± 3 nm, polydispersity (PDI) of 0.28 ± 0.28 and zeta potential of -18.8 ± 1.2 mV) nanoparticles. The results showed that there is a correlation between nanoparticles stability and the presence of NOM in the medium and Environmental Concentrations (EC) values. The stability loss or an increase in nanoparticle size result in low toxicity for R. subcapitata and L. minor. For D. magna and D. rerio, the presence of NOM in the medium reduces the ecotoxic effects for ATZ NPZ nanoparticles, but not for ATZ NPs, showing that the nanoparticles characteristics and their interaction with NOM can modulate toxic effects. Nanoparticle stability throughout the evaluation must be considered and become an integral part of toxicity protocol guidelines for nanopesticides, to ensure test quality and authentic results regarding nanopesticide effects in target and non-target organisms.

Microfibrous Scaffolds Guide Stem Cell Lumenogenesis and Brain Organoid Engineering

3D organoids are widely used as tractable in vitro models capable of elucidating aspects of human development and disease. However, the manual and low-throughput culture methods, coupled with a low reproducibility and geometric heterogeneity, restrict the scope and application of organoid research. Combining expertise from stem cell biology and bioengineering offers a promising approach to address some of these limitations. Here, melt electrospinning writing is used to generate tuneable grid scaffolds that can guide the self-organization of pluripotent stem cells into patterned arrays of embryoid bodies. Grid geometry is shown to be a key determinant of stem cell self-organization, guiding the position and size of emerging lumens via curvature-controlled tissue growth. Two distinct methods for culturing scaffold-grown embryoid bodies into either interconnected or spatially discrete cerebral organoids are reported. These scaffolds provide a high-throughput method to generate, culture, and analyze large numbers of organoids, substantially reducing the time investment and manual labor involved in conventional methods of organoid culture. It is anticipated that this methodological development will open up new opportunities for guiding pluripotent stem cell culture, studying lumenogenesis, and generating large numbers of uniform organoids for high-throughput screening.

Cryo-Electrospinning Generates Highly Porous Fiber Scaffolds Which Improves Trabecular Meshwork Cell Infiltration

Human trabecular meshwork is a sieve-like tissue with large pores, which plays a vital role in aqueous humor outflow. Dysfunction of this tissue can occur, which leads to glaucoma and permanent vision loss. Replacement of trabecular meshwork with a tissue-engineered device is the ultimate objective. This study aimed to create a biomimetic structure of trabecular meshwork using electrospinning. Conventional electrospinning was compared to cryogenic electrospinning, the latter being an adaptation of conventional electrospinning whereby dry ice is incorporated in the fiber collector system. The dry ice causes ice crystals to form in-between the fibers, increasing the inter-fiber spacing, which is retained following sublimation. Structural characterization demonstrated cryo-scaffolds to have closer recapitulation of the trabecular meshwork, in terms of pore size, porosity, and thickness. The attachment of a healthy, human trabecular meshwork cell line (NTM5) to the scaffold was not influenced by the fabrication method. The main objective was to assess cell infiltration. Cryo-scaffolds supported cell penetration deep within their structure after seven days, whereas cells remained on the outer surface for conventional scaffolds. This study demonstrates the suitability of cryogenic electrospinning for the close recapitulation of trabecular meshwork and its potential as a 3D in vitro model and, in time, a tissue-engineered device.

Nedaplatin/Peganum harmala Alkaloids Co-Loaded Electrospun, Implantable Nanofibers: A Chemopreventive Nano-Delivery System for Treating and Preventing Breast Cancer Recurrence after Tumorectomy

Currently, the main pillars in treating breast cancer involve tumorectomy pursued by hormonal, radio, or chemotherapies. Nonetheless, these approaches exhibit severe adverse effects and might suffer from tumor recurrence. Therefore, there is a considerable demand to fabricate an innovative controlled-release nano-delivery system to be implanted after tumor surgical removal to guard against cancer recurrence. In addition, combining platinum-based drugs with phytochemicals is a promising approach to improving the anticancer activity of the chemotherapeutics against tumor cells while minimizing their systemic effects. This study designed polycaprolactone (PCL)-based electrospun nanofiber mats encapsulating nedaplatin (N) and Peganum harmala alkaloid-rich fraction (L). In addition to physicochemical characterization, including average diameters, morphological features, degradation study, thermal stability, and release kinetics study, the formulated nanofibers were assessed in terms of cytotoxicity, where they demonstrated potentiated effects and higher selectivity towards breast cancer cells. The dual-loaded nanofiber mats (N + L@PCL) demonstrated the highest antiproliferative effects against MCF-7 cells with a recorded IC50 of 3.21 µg/mL, as well as the topmost achieved selectivity index (20.45) towards cancer cells amongst all the tested agents (N, L, N@PCL, and L@PCL). This indicates that the dual-loaded nanofiber excelled at conserving the normal breast epithelial cells (MCF-10A). The combined therapy, N + L@PCL treatment, resulted in a significantly higher percent cell population in the late apoptosis and necrosis quartiles as compared to all other treatment groups (p-value of ≤0.001). Moreover, this study of cell cycle kinetics revealed potentiated effects of the dual-loaded nanofiber (N + L@PCL) at trapping more than 90% of cells in the sub-G1 phase and reducing the number of cells undergoing DNA synthesis in the S-phase by 15-fold as compared to nontreated cells; hence, causing cessation of the cell cycle and confirming the apoptosis assay results. As such, our findings suggest the potential use of the designed nanofiber mats as perfect implants to prevent tumor recurrence after tumorectomy.

Development and Characterization of Electrospun Composites Built on Polycaprolactone and Cerium-Containing Phases

The current study reports on the fabrication of composite scaffolds based on polycaprolactone (PCL) and cerium (Ce)-containing powders, followed by their characterization from compositional, structural, morphological, optical and biological points of view. First, CeO2, Ce-doped calcium phosphates and Ce-substituted bioglass were synthesized by wet-chemistry methods (precipitation/coprecipitation and sol-gel) and subsequently loaded on PCL fibres processed by electrospinning. The powders were proven to be nanometric or micrometric, while the investigation of their phase composition showed that Ce was present as a dopant within the crystal lattice of the obtained calcium phosphates or as crystalline domains inside the glassy matrix. The best bioactivity was attained in the case of Ce-containing bioglass, while the most pronounced antibacterial effect was visible for Ce-doped calcium phosphates calcined at a lower temperature. The scaffolds were composed of either dimensionally homogeneous fibres or mixtures of fibres with a wide size distribution and beads of different shapes. In most cases, the increase in polymer concentration in the precursor solution ensured the achievement of more ordered fibre mats. The immersion in SBF for 28 days triggered an incipient degradation of PCL, evidenced mostly through cracks and gaps. In terms of biological properties, the composite scaffolds displayed a very good biocompatibility when tested with human osteoblast cells, with a superior response for the samples consisting of the polymer and Ce-doped calcium phosphates.