Recent trends on polycaprolactone as sustainable polymer-based drug delivery system in the treatment of cancer: Biomedical applications and nanomedicine

The unique properties-such as biocompatibility, biodegradability, bio-absorbability, low cost, easy fabrication, and high versatility-have made polycaprolactone (PCL) the center of attraction for researchers. The derived introduction in this manuscript gives a pretty detailed overview of PCL, so you can first brush up on it. Discussion on the various PCL-based derivatives involves, but is not limited to, poly(ε-caprolactone-co-lactide) (PCL-co-LA), PCL-g-PEG, PCL-g-PMMA, PCL-g-chitosan, PCL-b-PEO, and PCL-g-PU specific properties and their probable applications in biomedicine. This paper has considered examining the differences in the diverse disease subtypes and the therapeutic value of using PCL. Advanced strategies for PCL in delivery systems are also considered. In addition, this review discusses recently patented products to provide a snapshot of recent updates in this field. Furthermore, the text probes into recent advances in PCL-based DDS, for example, nanoparticles, liposomes, hydrogels, and microparticles, while giving special attention to comparing the esters in the delivery of bioactive compounds such as anticancer drugs. Finally, we review future perspectives on using PCL in biomedical applications and the hurdles of PCL-based drug delivery, including fine-tuning mechanical strength/degradation rate, biocompatibility, and long-term effects in living systems.

Antimicrobial peptide immobilization on catechol-functionalized PCL/alginate wet-spun fibers to combat surgical site infection

Surgical site infection (SSI) caused by pathogenic bacteria leads to delayed wound healing and extended hospitalization. Inappropriate uses of antibiotics have caused a surge in SSI and common antibiotics are proving to be ineffective against SSI. Antimicrobial peptides (AMPs) can be a potential solution to prevent SSI because of their broad spectrum of antimicrobial activities. In this study, naturally sourced AMPs were studied along with microfibers, fabricated by a novel wet-spinning method using sodium alginate and polycaprolactone. Afterward, fibers were functionalized by the catechol groups of dopamine immobilizing nucleophilic AMPs on the surface. Conjugation between PCL and alginate resulted in fibers with smooth surfaces improving their mechanical strength via hydrogen bonds. Having an average diameter of 220 μm, the mechanical properties of the fiber complied with USP standards for suture size 3-0. Engineered microfibers were able to hinder the growth of Proteus spp., a pathogenic bacterium for at least 60 hours whereas antibiotic ceftazidime failed. When subjected to a linear incisional wound model study, accelerated healing was observed when the wound was closed using the engineered fiber compared to Vicryl. The microfibers promoted faster re-epithelialization compared to Vicryl proving their higher wound healing capacity.

Electrospun scaffolds based on a PCL/starch blend reinforced with CaO nanoparticles for bone tissue engineering

Electrospun nanocomposite scaffolds with improved bioactive and biological properties were fabricated from a blend of polycaprolactone (PCL) and starch, and then combined with 5 wt% of calcium oxide (CaO) nanoparticles sourced from eggshells. SEM analyses showed scaffolds with fibrillar morphology and a three-dimensional structure. The hydrophilicity of scaffolds was improved with starch and CaO nanoparticles, which was evidenced by enhanced water absorption (3500 %) for 7 days. In addition, PCL/Starch/CaO scaffolds exhibited major degradation, with a mass loss of approximately 60 % compared to PCL/Starch and PCL/CaO. The PCL/Starch/CaO scaffolds decreased in crystallinity as intermolecular interactions between the nanoparticles retarded the mobility of the polymeric chains, leading to a significant increase in Young's modulus (ca. 60 %) and a decrease in tensile strength and elongation at break, compared to neat PCL. SEM-EDS, FT-IR, and XRD analyses indicated that PCL/Starch/CaO scaffolds presented a higher biomineralization capacity due to the ability to form hydroxyapatite (HA) in their surface after 28 days. The PCL/Starch/CaO scaffolds showed attractive biological performance, allowing cell adhesion and viability of M3T3-E1 preosteoblastic cells. In vivo analysis using a subdermal dorsal model in Wistar rats showed superior biocompatibility and improved resorption process compared to a pure PCL matrix. This biological analysis suggested that the PCL/Starch/CaO electrospun mats are suitable scaffolds for guiding the regeneration of bone tissue.

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.

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.

Sodium Alginate- and Cationic Cellulose-Functionalized Polycaprolactone Nanofibers for In Vitro and Antibacterial Applications

The use of polyelectrolytes is emerging as a fascinating strategy for the functionalization of biomedical membranes, due to their ability to enhance biological responses using the interaction effect of charged groups on multiple interface properties. Herein, two different polyelectrolytes were used to improve the antibacterial properties of polycaprolactone (PCL) nanofibers fabricated via electrospinning. First, a new cationic cellulose derivative, cellulose-bearing imidazolium tosylate (CIMD), was prepared via the nucleophilic substitution of the tosyl group using 1-methylimidazole, as confirmed by NMR analyses, and loaded into the PCL nanofibers. Secondly, sodium alginate (SA) was used to uniformly coat the fibers' surface via self-assembly, as remarked through SEM-EDX analyses. Polyelectrolyte interactions between the CIMD and the SA, initially detected using a FTIR analysis, were confirmed via Z potential measurements: the formation of a CMID/SA complex promoted a substantial charge neutralization of the fibers' surfaces with effects on the physical properties of the membrane in terms of water adsorption and in vitro degradation. Moreover, the presence of SA contributed to the in vitro response of human mesenchymal stem cells (hMSCs), as confirmed by a significant increase in the cells' viability after 7 days in the case of the PCL/CMID/SA complex with respect to the PCL and PCL/CMID membranes. Contrariwise, SA did not nullify the antibacterial effect of CMID, as confirmed by the comparable resistance exhibited by S. mutans, S. aureus, and E. coli to the PCL/CIMD and PCL/CIMD/SA membranes. All the reported results corroborate the idea that the CIMD/SA functionalization of PCL nanofibers has a great potential for the fabrication of efficient antimicrobial membranes for wound healing.

Fabrication of highly ordered willemite/PCL bone scaffolds by 3D printing: Nanostructure effects on compressive strength and in vitro behavior

In this study, first willemite (Zn₂SiO₄) micro and nano-powders were synthesized by the sol-gel method. X-ray diffraction (XRD), transmission electron microscopy (TEM), and dynamic light scattering (DLS) were applied to characterize the crystalline phases and particle size of powders. Then polycaprolactone (PCL) polymer scaffolds containing 20 wt% willemite were successfully fabricated by the DIW 3D printing (direct ink writing) method. The effects of willemite particle size on compressive strength, elastic modulus, degradation rate, and bioactivity of the composite scaffolds were investigated. The results showed that nanoparticle willemite/PCL (NW/PCL) scaffolds had 33.1% and 58.1% higher compressive strength and the elastic modulus of NW/PCL were 1.14 and 2.45 times better compared to micron size willemite/PCL (MW/PCL) and pure PCL scaffolds, respectively. Scanning electron microscopy (SEM) images and Energy-dispersive X-ray spectroscopy map (EDS map) results indicated that willemite nanoparticles, unlike microparticles, were smoothly embedded in the scaffold struts. In vitro tests also revealed an improvement in bone-like apatite formation ability and an increase in the degradation rate up to 2.17% by decreasing the willemite particle size to 50 nm. In addition, NW/PCL rendered significant enhancement in cell viability and cell attachment during the culture of MG-63 human osteosarcoma cell line. Nanostructure had also a positive effect on ALP activity and biomineralization in vitro.

Capsaicin-loaded alginate nanoparticles embedded polycaprolactone-chitosan nanofibers as a controlled drug delivery nanoplatform for anticancer activity

Nanocarrier-based drug delivery systems have been designed into various structures that can effectively prevent cancer progression and improve the therapeutic cancer index. However, most of these delivery systems are designed to be simple nanostructures with several limitations, including low stability and burst drug release features. A nano-in-nano delivery technique is explored to address the aforementioned concerns. Accordingly, this study investigated the release behavior of a novel nanoparticles-in-nanofibers delivery system composed of capsaicin-loaded alginate nanoparticles embedded in polycaprolactone-chitosan nanofiber mats. First, alginate nanoparticles were prepared with different concentrations of cationic gemini surfactant and using nanoemulsion templates. The optimized formulation of alginate nanoparticles was utilized for loading capsaicin and exhibited a diameter of 19.42 ± 1.8 nm and encapsulation efficiency of 98.7 % ± 0.6 %. Likewise, blend polycaprolactone-chitosan nanofibers were prepared with different blend ratios of their solutions (i.e., 100:0, 80:20, 60:40) by electrospinning method. After the characterization of electrospun mats, the optimal nanofibers were employed for embedding capsaicin-loaded alginate nanoparticles. Our findings revealed that embedding capsaicin-loaded alginate nanoparticles in polycaprolactone-chitosan nanofibers, prolonged capsaicin release from 120 h to more than 500 h. Furthermore, the results of in vitro analysis demonstrated that the designed nanoplatform could effectively inhibit the proliferation of MCF-7 human breast cells while being nontoxic to human dermal fibroblasts (HDF). Collectively, the prepared nanocomposite drug delivery platform might be promising for the long-term and controlled release of capsaicin for the prevention and treatment of cancer.

Electrospun Polycaprolactone/Chitosan Nanofibers Containing Cordia myxa Fruit Extract as Potential Biocompatible Antibacterial Wound Dressings

The goal of the current work was to create an antibacterial agent by using polycaprolactone/chitosan (PCL/CH) nanofibers loaded with Cordia myxa fruit extract (CMFE) as an antimicrobial agent for wound dressing. Several characteristics, including morphological, physicomechanical, and mechanical characteristics, surface wettability, antibacterial activity, cell viability, and in vitro drug release, were investigated. The inclusion of CMFE in PCL/CH led to increased swelling capability and maximum weight loss. The SEM images of the PCL/CH/CMFE mat showed a uniform topology free of beads and an average fiber diameter of 195.378 nm. Excellent antimicrobial activity was shown towards Escherichia coli (31.34 ± 0.42 mm), Salmonella enterica (30.27 ± 0.57 mm), Staphylococcus aureus (21.31 ± 0.17 mm), Bacillus subtilis (27.53 ± 1.53 mm), and Pseudomonas aeruginosa (22.17 ± 0.12 mm) based on the inhibition zone assay. The sample containing 5 wt% CMFE had a lower water contact angle (47 ± 3.7°), high porosity, and high swelling compared to the neat mat. The release of the 5% CMFE-loaded mat was proven to be based on anomalous non-Fickian diffusion using the Korsmeyer–Peppas model. Compared to the pure PCL membrane, the PCL-CH/CMFE membrane exhibited suitable cytocompatibility on L929 cells. In conclusion, the fabricated antimicrobial nanofibrous films demonstrated high bioavailability, with suitable properties that can be used in wound dressings.

Innovation in the Development of Synthetic and Natural Ocular Drug Delivery Systems for Eye Diseases Treatment: Focusing on Drug-Loaded Ocular Inserts, Contacts, and Intraocular Lenses

Nowadays, ocular drug delivery still remains a challenge, since the conventional dosage forms used for anterior and posterior ocular disease treatments, such as topical, systemic, and intraocular administration methods, present important limitations mainly related to the anatomical complexity of the eye. In particular, the blood-ocular barrier along with the corneal barrier, ocular surface, and lacrimal fluid secretion reduce the availability of the administered active compounds and their efficacy. These limitations have increased the need to develop safe and effective ocular delivery systems able to sustain the drug release in the interested ocular segment over time. In the last few years, thanks to the innovations in the materials and technologies employed, different ocular drug delivery systems have been developed. Therefore, this review aims to summarize the synthetic and natural drug-loaded ocular inserts, contacts, and intraocular lenses that have been recently developed, emphasizing the characteristics that make them promising for future ocular clinical applications.

Polyaniline-polycaprolactone electrospun nanofibrous mat: new polymeric support with anion exchange characteristic for immobilizing liquid membrane in efficient on-chip electromembrane extraction of polar acidic drugs

The potential of application of an electrospun nanofiber sheet as new polymeric support for immobilizing the liquid membrane, instead of a common commercial polypropylene sheet, in on-chip electromembrane extraction (EME) of some acidic polar drugs followed by HPLC with ultraviolet detection is presented. The nanofiber sheet was prepared by electrospinning a mixture of polycaprolactone and polyaniline. The successful synthesis of the electrospun nanofiber sheet was confirmed by field emission-scanning electron microscopy, energy-dispersive X-ray spectroscopy, elemental mapping, and atomic force microscopy. Several parameters affecting the efficiency of the microextraction method, including pHs of the donor and acceptor phases, applied voltage, sample flow rate, phosphate content of the acceptor phase, and sample volume, were investigated and optimized. After optimization, the linearity range of 0.5-250.0 µg L^-1 and detection limits of 0.2-1.0 µg L^-1 were obtained for the analytes. The extraction recovery values and preconcentration factors were 10.7-55.3% and 16-83, respectively. The presence of polyaniline in the composition of the nanofibers significantly improved the extraction efficiency of the polar acidic drugs due to providing the possibility of various interactions with the target analytes such as hydrogen bonding, π-stacking, and anion exchange. The obtained results demonstrate the excellent efficiency of the synthesized electrospun nanofibrous mat as a novel support membrane for immobilizing 1-octanol and as an interactive substrate for electromembrane extraction of acidic polar drugs. Eventually, the proposed on-chip EME method exhibits acceptable precision (relative standard deviations less than 9.7% (n = 3)) and good accuracy (86-112%) for determining the target analytes in the plasma samples.

Solvent system effects on the physical and mechanical properties of electrospun Poly(ε-caprolactone) scaffolds for in vitro lung models

Mechanical properties are among the key considerations for the design and fabrication of complex tissue models and implants. In addition to the choice of material and the processing technique, the solvent system can significantly influence the mechanical properties of scaffolds. Poly(ε-caprolactone) (PCL) has been abundantly used to develop constructs, fibrous in particular, for pharmaceutical and biomedical research due to the flexibility offered by PCL-based fibrous matrices. The effect of solvent type on the morphological features of electrospun fibres has been extensively studied. Nevertheless, comprehensive studies on the impact of the solvent system on the mechanical properties of electrospun PCL fibres are lacking. This study elucidates the relationship between topographical, physical and mechanical properties of electrospun PCL fibrous meshes upon using various solvent systems. The results of the mechanical investigation highlight the significance of inter-fibre bonds on the mechanical properties of the bulk membranes and that the option of altering the solvent system composition could be considered for tuning the mechanical properties of the PCL scaffolds to serve specific biomedical application requirements. The applicability of the developed membranes as artificial ECM (Extracellular matrix) in the lung will then be investigated and compared to the commercial Polycarbonate (PC) membranes that are often used for in vitro lung models.

Chain-End Functionalization of Poly(ε-caprolactone) for Chemical Binding with Gelatin: Binary Electrospun Scaffolds with Improved Physico-Mechanical Characteristics and Cell Adhesive Properties

Composite biocompatible scaffolds, obtained using the electrospinning (ES) technique, are highly promising for biomedical application thanks to their high surface area, porosity, adjustable fiber diameter, and permeability. However, the combination of synthetic biodegradable (such as poly(ε-caprolactone) PCL) and natural (such as gelatin Gt) polymers is complicated by the problem of low compatibility of the components. Previously, this problem was solved by PCL grafting and/or Gt cross-linking after ES molding. In the present study, composite fibrous scaffolds consisting of PCL and Gt were fabricated by the electrospinning (ES) method using non-functionalized PCL1 or NHS-functionalized PCL2 and hexafluoroisopropanol as a solvent. To provide covalent binding between PCL2 and Gt macromolecules, NHS-functionalized methyl glutarate was synthesized and studied in model reactions with components of spinning solution. It was found that selective formation of amide bonds, which provide complete covalent bonding of Gt in PCL/Gt composite, requires the presence of weak acid. With the use of the optimized ES method, fibrous mats with different PCL/Gt ratios were prepared. The sample morphology (SEM), hydrolytic resistance (FT-IR), cell adhesion and viability (MTT assay), cell penetration (fluorescent microscopy), and mechanical characteristics of the samples were studied. PCL2-based films with a Gt content of 20 wt% have demonstrated the best set of properties.

Iron-Based Magnetic Nanosystems for Diagnostic Imaging and Drug Delivery: Towards Transformative Biomedical Applications

The advancement of biomedicine in a socioeconomically sustainable manner while achieving efficient patient-care is imperative to the health and well-being of society. Magnetic systems consisting of iron based nanosized components have gained prominence among researchers in a multitude of biomedical applications. This review focuses on recent trends in the areas of diagnostic imaging and drug delivery that have benefited from iron-incorporated nanosystems, especially in cancer treatment, diagnosis and wound care applications. Discussion on imaging will emphasise on developments in MRI technology and hyperthermia based diagnosis, while advanced material synthesis and targeted, triggered transport will be the focus for drug delivery. Insights onto the challenges in transforming these technologies into day-to-day applications will also be explored with perceptions onto potential for patient-centred healthcare.

Antitumor Efficacy of Doxorubicin-Loaded Electrospun Attapulgite–Poly(lactic-co-glycolic acid) Composite Nanofibers

Currently, cancer chemotherapeutic drugs still have the defects of high toxicity and low bioavailability, so it is critical to design novel drug release systems for cancer chemotherapy. Here, we report a method to fabricate electrospun drug-loaded organic/inorganic hybrid nanofibrous system for antitumor therapy applications. In this work, rod-like attapulgite (ATT) was utilized to load a model anticancer drug doxorubicin (DOX), and mixed with poly(lactic-co-glycolic acid) (PLGA) to form electrospun hybrid nanofibers. The ATT/DOX/PLGA composite nanofibers were characterized through various techniques. It is feasible to load DOX onto ATT surfaces, and the ATT/DOX/PLGA nanofibers show a smooth and uniform morphology with improved mechanical durability. Under neutral and acidic pH conditions, the loaded DOX was released from ATT/DOX/PLGA nanofibers in a sustained manner. In addition, the released DOX from the nanofibers could significantly inhibit the growth of tumor cells. Owing to the significantly reduced burst release profile and increased mechanical durability of the ATT/DOX/PLGA nanofibers, the designed organic–inorganic hybrid nanofibers may hold great promise as a nanoplatform to encapsulate different drugs for enhanced local tumor therapy applications.

Effects of Electrospinning Parameter Adjustment on the Mechanical Behavior of Poly-ε-caprolactone Vascular Scaffolds

Electrospinning is a perspective method widely suggested for use in bioengineering applications, but the variability in currently available data and equipment necessitates additional research to ascertain the desirable methodology. In this study, we aimed to describe the effects of electrospinning technique alterations on the structural and mechanical properties of (1,7)-polyoxepan-2-one (poly-ε-caprolactone, PCL) scaffolds, such as circumferential and longitudinal stress/strain curves, in comparison with corresponding properties of fresh rat aorta samples. Scaffolds manufactured under different electrospinning modes were analyzed and evaluated using scanning electronic microscopy as well as uniaxial longitudinal and circumferential tensile tests. Fiber diameter was shown to be the most crucial characteristic of the scaffold, correlating with its mechanical properties.

Fine Crystalline Mg-Al Hydrotalcites as Catalysts for Baeyer-Villiger Oxidation of Cyclohexanone with H2O2

The catalytic activity of Mg-Al hydrotalcite (HT) materials in base-catalyzed reactions is known to be promoted by the low crystallinity of the HT solid. In the present work, two routes enabling the preparation of finely crystalline Mg-Al HT materials were explored: (1) the inverse microemulsion technique, and (2) co-precipitation in the presence of starch. Carbonate, chloride and bromide forms of HT were prepared, examined with X-ray diffraction, scanning electron microscopy/energy dispersive X-ray spectroscopy and infrared spectroscopy, and used as catalysts in the Baeyer–Villiger oxidation of cyclohexanone to ε-caprolactone with a H2O2/acetonitrile system. The bromide forms proved significantly less active than the chlorides and carbonates, as they promoted nonselective consumption of H2O2. The fine crystalline materials were more active than the more crystalline HT references obtained by conventional co-precipitation. Catalysts prepared by inverse microemulsion were less crystalline and more active than the starch-templated ones, but suffered stronger deactivation by the acidic reaction environment. Alkalization of the reaction medium with NaHCO3 stabilized the HT materials and increased the ε-caprolactone yield, which became comparable for both types of fine crystalline catalysts—thus pointing to the synthesis involving a simple and cheap starch templating approach as being a particularly attractive one.

Thermal Stability and Dynamic Mechanical Properties of Poly(ε-caprolactone)/Chitosan Composite Membranes

Poly (ε-caprolactone) (PCL) and chitosan (CS) are widely used as biodegradable and biocompatible polymers with desirable properties for tissue engineering applications. Composite membranes (CS-PCL) with various blend ratios (CS:PCL, w/w) of 0:100, 5:95, 10:90, 15:85, 20:80, and 100:0 were successfully prepared by lyophilization. The thermal stabilities of the CS-PCL membranes were systematically characterized by thermogravimetric analysis (TG), dynamic thermogravimetry (DTG), and differential scanning calorimetry (DSC). It was shown that the blend ratio of PCL and CS had a significant effect on the thermal stability, hydrophilicity, and dynamic mechanical viscoelasticity of the CS-PCL membranes. All the samples in the experimental range exhibited high elasticity at low temperature and high viscosity at high temperatures by dynamic mechanical thermal analysis (DMTA). The performances of the CS-PCL membranes were at optimum levels when the blend ratio (w/w) was 10:90. The glass transition temperature of the CS-PCL membranes increased from 64.8 °C to 76.6 °C compared to that of the pure PCL, and the initial thermal decomposition temperature reached 86.7 °C. The crystallinity and porosity went up to 29.97% and 85.61%, respectively, while the tensile strength and elongation at the breakage were 20.036 MPa and 198.72%, respectively. Therefore, the 10:90 (w/w) blend ratio of CS/PCL is recommended to prepare CS-PCL membranes for tissue engineering applications.

Structure and biological compatibility of polycaprolactone/zinc-hydroxyapatite electrospun nanofibers for tissue regeneration

Although guided tissue regeneration (GTR) is a useful tool for regenerating lost tissue as bone and periodontal tissue, a biocompatible membrane capable of regenerating large defects has yet to be discovered. This study aimed to characterize the physicochemical properties and biological compatibility of polycaprolactone (PCL) membranes associated with or without nanostructured hydroxyapatite (HA) (PCL/HA) and Zn-doped HA (PCL/ZnHA), produced by electrospinning. PCL, PCL/HA, and PCL/ZnHA were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC). Nanoparticles of HA or ZnHA were homogeneously distributed and dispersed inside the PCL fibers, which decreased the fiber thickness. At 1 wt% of HA or ZnHA, these nanoparticles acted as nucleating agents. Moreover, HA and ZnHA increased the onset of the degradation temperature and thermal stability of the electrospun membrane. All tested membranes showed no cytotoxicity and allowed murine pre-osteoblast adhesion and spreading; however, higher concentrations of PCL/ZnHA showed less cells and an irregular cell morphology compared to PCL and PCL/HA. This article presents a cytocompatible, electrospun, nanocomposite membrane with a novel morphology and physicochemical properties that make it eligible as a scaffold for GTR.

Fabrication and characterization of electrospun biopolyester/gelatin nanofibers

Poly(ω-pentadecalactone-co-ε-caprolactone) copolymer (PDL-CL) is an enzymatically synthesized aliphatic biopolyester, which has been participated in a nanofibrous structure for the first time. Electrospinning of this synthetic polymer by blending with a natural polymer such as gelatin (Gel) could provide new characteristics that are significant for biomedical applications, such as drug delivery, wound healing, and tissue engineering. In the present study, PDL-CL/Gel nanofibrous membranes were successfully produced and characterized. The average diameter of nanofibers was 305.0 ± 45.5 nm that may be beneficial in applications mentioned above. In order to increase hydrolytic resistance, cross-linking with glutaraldehyde vapor was applied. Cross-linking for 2 h was enough to obtain a nanofibrous membrane that was able to resist in pH 7.4 phosphate buffered saline for 30 days. In addition, contact angle measurement results had shown that, cross-linked nanofibrous membrane had good wettability, which is a required specification to be applied in biomedical field. Hence, this study provides an overview on fabrication of fine PDL-CL/Gel nanofibers, which may have potential to be used in biomedical area.

Poly(gallic acid)-coated polycaprolactone inhibits oxidative stress in epithelial cells

Enzymatic mediated poly (gallic acid) (PGAL), a stable multiradical polyanion with helicoidal secondary structure and high antioxidant capacity, was successfully grafted to poly(ε-caprolactone) (PCL) using UV-photo induction. PCL films were prepared with several levels of roughness and subsequently grafted with PGAL (PCL-g-PGAL). The results on the full characterization of the produced materials by mechanical tests, surface morphology, and topography, thermal and crystallographic analyses, as well as wettability and cell protection activity against oxidative stress, were adequate for tissue regeneration. The in vitro biocompatibility was then assessed with epithelial-like cells showing excellent adhesion and proliferation onto the PCL-g-PGAL films, most importantly, PCL-g-PGAL displayed a good ability to protect cell cultures on their surface against reactive oxygen species. These biomaterials can consequently be considered as novel biocompatible and antioxidant films with high-responsiveness for biomedical or tissue engineering applications.

Biocompatible PCL-nanofibers scaffold with immobilized fibronectin and laminin for neuronal tissue regeneration

Recent advances in regenerative medicine have given hope in overcoming and rehabilitating complex medical conditions. In this regard, the biopolymer poly-ε-caprolactone (PCL) may be a promising candidate for tissue regeneration, despite lacking the essential bioactivity. The present study used PCL nanofibers (NFs) scaffold decorated with the extracellular matrix proteins fibronectin and laminin combined for neuronal regeneration. The potential for the dual proteins to support neuronal cells and promote axonal growth was investigated. Two NFs scaffolds were produced with PLC concentrations of 12% or 15%. Under scanning electron microscopy, both scaffolds evidenced uniform diameter distribution in the range of 358 nm and 887 nm, respectively, with >80% porosity. The Brunauer-Emmett-Teller (BET) test confirmed that the fabricated NFs mats had a high surface area, especially for the 12% NFs with 652 m²/g compared to 254 m²/g for the 15% NFs. The proteins of interest were successfully conjugated to the 12% PCL scaffold through chemical carbodiimide reaction as confirmed by Fourier-transform infrared spectroscopy. The addition of fibronectin and laminin together was shown to be the most favorable for cellular attachment and elongation of neuroblastoma SH-SY5Y cells compared to other formulations. Light microscopy revealed longer neurite outgrowth, higher cellular projected area, and lower shape index for the cells cultured on the combined proteins conjugated fibers, indicating enhanced cellular spread on the scaffold. This preliminary study suggests that PCL nanoscaffolding conjugated with matrix proteins can support neuronal cell viability and neurite growth.

Applications of materials for dural reconstruction in pre-clinical and clinical studies: Advantages and drawbacks, efficacy, and selections

The dura mater provides a barrier to protect the tissue underneath and cerebrospinal fluid. However, dural defects normally cause cerebrospinal fluid leakage and other complications, such as wound infections, meningitis, etc. Therefore, the reconstruction of dura mater has important clinical significance. Current dural reconstruction materials include: homologous, acellular, natural, synthetic, and composite materials. This review comprehensively summarizes the characteristics and efficacy of these dural substitutes, especially in clinical applications, including the advantages and drawbacks of those from different sources, the host tissue response in pre-clinical studies and clinical practice, and the comparison of these materials across different surgical procedures. Furthermore, the selections of materials for different surgical procedures are highlighted. Finally, the challenges and future perspectives in the development of ideal dural repair materials are discussed.

Multilayer Alginate-Polycaprolactone Electrospun Membranes as Skin Wound Patches with Drug Delivery Abilities

A multilayer nanofibrous membrane consisting of a layer of polycaprolactone and one of physically cross-linked alginate-embedding ZnO nanoparticles is prepared via electrospinning technique as potential wound healing patches with drug delivery capabilities. A washing-cross-linking protocol is developed to obtain stable materials at the same time removing poly(ethylene oxide), which was used here as a cospinning agent for alginate, without interfering with the membrane's peculiar nanofibrous structure. The mechanical behavior of the samples is assessed via a uniaxial tensile test showing appropriate resistance and manageability together with a good thermal stability as proved via thermogravimetric analysis. The polycaprolactone external layer enriches the samples with good liquid-repellent properties, whereas the alginate layer is able to promote tissue regeneration owing to its capability to promote cell viability and allow exudate removal and gas exchanges. Moreover, using methylene blue and methyl orange as model molecules, promising drug delivery abilities are observed for the mats. Indeed, depending on the nature and on the dye-loading concentration, the release kinetic can be easily tuned to obtain a slow controlled or a fast burst release. Consequently, the proposed alginate-polycaprolactone membrane represents a promising class of innovative, simple, and cost-effective wound healing patches appropriate for large-scale production.

Modification of PCL Scaffolds by Reactive Magnetron Sputtering: A Possibility for Modulating Macrophage Responses

Direct current (DC) reactive magnetron sputtering is as an efficient method for enhancing the biocompatibility of poly(ε-caprolactone) (PCL) scaffolds. However, the PCL chemical bonding state, the composition of the deposited coating, and their interaction with immune cells remain unknown. Herein, we demonstrated that the DC reactive magnetron sputtering of the titanium target in a nitrogen atmosphere leads to the formation of nitrogen-containing moieties and the titanium dioxide coating on the scaffold surface. We have provided the possible mechanism of PCL fragmentation and coating formation supported by XPS results and DFT calculations. Our preliminary biological studies suggest that DC reactive magnetron sputtering of the titanium target could be an effective tool to control macrophage functional responses toward PCL scaffolds as it allows to inhibit respiratory burst while retaining cell viability and scavenging activity.

High-Throughput Manufacture of 3D Fiber Scaffolds for Regenerative Medicine

Engineered scaffolds used to regenerate mammalian tissues should recapitulate the underlying fibrous architecture of native tissue to achieve comparable function. Current fibrous scaffold fabrication processes, such as electrospinning and three-dimensional (3D) printing, possess application-specific advantages, but they are limited either by achievable fiber sizes and pore resolution, processing efficiency, or architectural control in three dimensions. As such, a gap exists in efficiently producing clinically relevant, anatomically sized scaffolds comprising fibers in the 1-100 μm range that are highly organized. This study introduces a new high-throughput, additive fibrous scaffold fabrication process, designated in this study as 3D melt blowing (3DMB). The 3DMB system described in this study is modified from larger nonwovens manufacturing machinery to accommodate the lower volume, high-cost polymers used for tissue engineering and implantable biomedical devices and has a fiber collection component that uses adaptable robotics to create scaffolds with predetermined geometries. The fundamental process principles, system design, and key parameters are described, and two examples of the capabilities to create scaffolds for biomedical engineering applications are demonstrated. Impact statement Three-dimensional melt blowing (3DMB) is a new, high-throughput, additive manufacturing process to produce scaffolds composed of highly organized fibers in the anatomically relevant 1-100 μm range. Unlike conventional melt-blowing systems, the 3DMB process is configured for efficient use with the relatively expensive polymers necessary for biomedical applications, decreasing the required amounts of material for processing while achieving high throughputs compared with 3D printing or electrospinning. The 3DMB is demonstrated to make scaffolds composed of multiple fiber materials and organized into complex shapes, including those typical of human body parts.

Bone Healing in the Presence of a Biodegradable PBS-DLA Copolyester and Its Composite Containing Hydroxyapatite

The healing process of the fractured bone in a presence of poly(butylene succinate-butylene dilinoleate) (PBS-DLA) copolymer containing nanosized hydroxyapatite (HAP) particles has been investigated. The PBS-DLA material containing PBS hard segments and DLA soft segments (50:50 wt %) was used to prepare a polymer/ceramic composite with 30 wt % HAP. A new PBS-DLA copolymer showed a high elasticity of 500% and 15 MPa tensile strength. Addition of HAP improved tensile strength up to 25 MPa while high elasticity has been preserved going down only to 300% of elongation at break. A polymer nanocomposite was fabricated into small elastic polymer rods 15 mm long and 1 × 2 mm in cross section and used for tibia bone fixation in rats. Mallory trichrome staining indicated that new biodegradable copolymers and its composite containing HAP have triggered the most advanced bone healing of all tested materials, thus indicating their high potential for bone tissue engineering and repair.

Alfalfa Nanofibers for Dermal Wound Healing

Engineering bioscaffolds for improved cutaneous tissue regeneration remains a healthcare challenge because of the increasing number of patients suffering from acute and chronic wounds. To help address this problem, we propose to utilize alfalfa, an ancient medicinal plant that contains antibacterial/oxygenating chlorophylls and bioactive phytoestrogens, as a building block for regenerative wound dressings. Alfalfa carries genistein, which is a major phytoestrogen known to accelerate skin repair. The scaffolds presented herein were built from composite alfalfa and polycaprolactone (PCL) nanofibers with hydrophilic surface and mechanical stiffness that recapitulate the physiological microenvironments of skin. This composite scaffold was engineered to have aligned nanofibrous architecture to accelerate directional cell migration. As a result, alfalfa-based composite nanofibers were found to enhance the cellular proliferation of dermal fibroblasts and epidermal keratinocytes in vitro. Finally, these nanofibers exhibited reproducible regenerative functionality by promoting re-epithelialization and granulation tissue formation in both mouse and human skin, without requiring additional proteins, growth factors, or cells. Overall, these findings demonstrate the potential of alfalfa-based nanofibers as a regenerative platform toward accelerating cutaneous tissue repair.

Scaffolding polymeric biomaterials: Are naturally occurring biological macromolecules more appropriate for tissue engineering?

Nowadays, tissue and organ failures resulted from injury, aging accounts, diseases or other type of damages is one of the most important health problems with an increasing incidence worldwide. Current treatments have limitations including, low graft efficiency, shortage of donor organs, as well as immunological problems. In this context, tissue engineering (TE) was introduced as a novel and versatile approach for restoring tissue/organ function using living cells, scaffold and bioactive (macro-)molecules. Among these, scaffold as a three-dimensional (3D) support material, provide physical and chemical cues for seeding cells and has an essential role in cell missions. Among the wide verity of scaffolding materials, natural or synthetic biopolymers are the most commonly biomaterials mainly due to their unique physicochemical and biological features. In this context, naturally occurring biological macromolecules are particular of interest owing to their low immunogenicity, excellent biocompatibility and cytocompatibility, as well as antigenicity that qualified them as popular choices for scaffolding applications. In this review, we highlighted the potentials of natural and synthetic polymers as scaffolding materials. The properties, advantages, and disadvantages of both polymer types as well as the current status, challenges, and recent progresses regarding the application of them as scaffolding biomaterials are also discussed.

Electrospin-Coating of Paper: A Natural Extracellular Matrix Inspired Design of Scaffold

Paper has recently found widespread applications in biomedical fields, especially as an alternative scaffolding material for cell cultures, owing to properties such as its fibrous nature, porosity and flexibility. However, paper on its own is not an optimal material for cell cultures as it lacks adhesion moieties specific to mammalian cells, and modifications such as hydrogel integration and chemical vapor deposition are necessary to make it a favorable scaffolding material. The present study focuses on modification of filter paper through electrospin-coating and dip-coating with polycaprolactone (PCL), a promising biomaterial in tissue engineering. Morphological analysis, evaluation of cell viability, alkaline phosphatase (ALP) activity and live/dead assays were conducted to study the potential of the modified paper-based scaffold. The results were compared to filter paper (FP) and electrospun PCL (ES-PCL) as reference samples. The results indicate that electrospin-coating paper is a simple and efficient way of modifying FP. It not only improves the morphology of the deposited electrospun layer through reduction of the fiber diameter by nearly 75%, but also greatly reduces the scaffold fabrication time compared to ES-PCL. The biochemical assays (Resazurin and ALP) indicate that electrospin-coated filter paper (ES-PCL/FP) provides significantly higher readings compared to all other groups. The live/dead results also show improved cell-distribution and cell-scaffold attachment all over the ES-PCL/FP.

Polymer scaffolds facilitate spinal cord injury repair

During the past decades, improving patient neurological recovery following spinal cord injury (SCI) has remained a challenge. An effective treatment for SCI would not only reduce fractured elements and isolate developing local glial scars to promote axonal regeneration but also ameliorate secondary effects, including inflammation, apoptosis, and necrosis. Three-dimensional (3D) scaffolds provide a platform in which these mechanisms can be addressed in a controlled manner. Polymer scaffolds with favorable biocompatibility and appropriate mechanical properties have been engineered to minimize cicatrization, customize drug release, and ensure an unobstructed space to promote cell growth and differentiation. These properties make polymer scaffolds an important potential therapeutic platform. This review highlights the recent developments in polymer scaffolds for SCI engineering. STATEMENT OF SIGNIFICANCE: How to improve the efficacy of neurological recovery after spinal cord injury (SCI) is always a challenge. Tissue engineering provides a promising strategy for SCI repair, and scaffolds are one of the most important elements in addition to cells and inducing factors. The review highlights recent development and future prospects in polymer scaffolds for SCI therapy. The review will guide future studies by outlining the requirements and characteristics of polymer scaffold technologies employed against SCI. Additionally, the peculiar properties of polymer materials used in the therapeutic process of SCI also have guiding significance to other tissue engineering approaches.

Fabrication of Electrospun Polymer Nanofibers with Diverse Morphologies

Fiber structures with nanoscale diameters offer many fascinating features, such as excellent mechanical properties and high specific surface areas, making them attractive for many applications. Among a variety of technologies for preparing nanofibers, electrospinning is rapidly evolving into a simple process, which is capable of forming diverse morphologies due to its flexibility, functionality, and simplicity. In such review, more emphasis is put on the construction of polymer nanofiber structures and their potential applications. Other issues of electrospinning device, mechanism, and prospects, are also discussed. Specifically, by carefully regulating the operating condition, modifying needle device, optimizing properties of the polymer solutions, some unique structures of core⁻shell, side-by-side, multilayer, hollow interior, and high porosity can be obtained. Taken together, these well-organized polymer nanofibers can be of great interest in biomedicine, nutrition, bioengineering, pharmaceutics, and healthcare applications.

PCL–DOX microdroplets: an evaluation of the enhanced intracellular delivery of doxorubicin in metastatic cancer cells via in silico and in vitro approaches

A schematic diagram of HCC & TACE; injections of HepaSphere with DOX are made into the femoral artery, abdominal aorta, and hepatic artery to make the tumor shrink to a resectable size due to a shortage of nutrients and drug treatment.

The effects of nanoparticles on morphology and thermal properties of erythritol/polyvinyl alcohol phase change composite fibers

Erythritol (E)/polyvinyl alcohol (PVA) phase change composite fibers in which PVA acts as supporting material and different contents of erythritol act as phase change materials (PCMs) were prepared by electrospinning. The effects of different nanoparticles on fiber morphology and thermal properties of composites were also studied. The morphology and thermal properties were characterized by using scanning electron microscopy (SEM), differential scanning calorimetery (DSC) and a thermal conductivity test, respectively. The results showed E/PVA composite fibers were cylindrical with a smooth surface. The content of erythritol in composites could reach a high of 80 wt% with good shape stability, and a high enthalpy value of 258.9 J/g after 100 thermal cycles. The effects of nanoparticles on composites were mainly embodied in decreasing average fiber diameters (AFDs), phase change temperatures and enthalpies with the increase of particle concentrations, and improving fiber stability and thermal conductivity. Among them, the smallest AFDs (0.56 μm) and the lowest heat loss rate (1.0%) were obtained from composites with 4% nano C and 4% nano Al2O3, respectively. The 4% nano SiO2 composites possessed the best shape stability. In addition, the composites that contains 4% nano carbon could decrease the erythritol’s supercooling of 7.55°C, and showed the highest thermal conductivity of 1.55 W/m·K, which was 167% of E/PVA composites. These results demonstrate that E/PVA composites possess high enthalpy values while they improve shape stability and thermal conductivity.