Ternary blend nanofibres of poly(lactic acid), polycaprolactone and cellulose acetate butyrate for skin tissue scaffolds:influence of blend ratio and polycaprolactone molecular mass on miscibility, morphology, crystallinity and thermal properties

Ternary blends of poly(lactic acid) (PLA), polycaprolactone (PCL) and cellulose acetate butyrate (CAB) were fabricated into the form of electrospun nanofibres targeted for skin tissue scaffolds. The effects of blend ratio and molecular mass of PCL (PCL1 and PCL2) on morphology, miscibility, crystallinity, thermal properties, surface hydrophilicity and cell culture of the nanofibres were investigated. Blends with high PLA loading (80/10/10 PLA/PCL/CAB) gave fibres with a smooth surface, owing to the enhanced miscibility between the polymer chains from the presence of CAB, which acts as compatibilizer. In contrast, blends with high PCL loading were immiscible, which led to beads during the electrospinning process. The increased molecular mass of PCL2 produced smoother fibres than low-molecular-mass PCL1. The XRD patterns of blends of PLA/PCL1/CAB and PLA/PCL2/CAB were similar to one another, in which the high-crystallinity peaks of PCL seen for 20/70/10 blends were very small for 50/40/10 blends and much less prevalent for 80/10/10 blends. Better fibre formation (80/10/10>50/40/10>20/70/10) with less crystallinity occurs in well-formed fibres. Selected blends of PLA/PCL/CAB promoted growth of NIH/3T3 fibroblast cells, demonstrating that our novel biocompatible ternary blend nanofibrous scaffolds have potential in skin tissue repair applications. In addition, this work helps in the design and understanding of the factors that control the properties of nanofibrous PLA/PCL/CAB scaffolds

Multifunctional core‐shell electrospun nanofibrous fabrics of poly(vinyl alcohol)/silk sericin (core) and poly(lactide‐ co ‐glycolide) (shell)

Core–shell fibres (CSFs) offer a simple route to multifunctional hybrid materials for a wide range of applications. Herein, we report the design of a core–shell electrospun nanofibrous fabric containing a hydrophilic core and hydrophobic shell. CSFs were fabricated for the first time from poly(vinyl alcohol)/silk sericin (from silk cocoons) as the core and poly(lactide-co-glycolide) as the shell. The core serves as a potential carrier for water-soluble bioactive agents, and the shell works as a barrier to prevent premature release of water-soluble agents from the core. The effect of the molecular weight of poly(lactide-co-glycolide) and the loading of silk sericin on the morphology of fibres was studied. The parameters that significantly influence the core–shell electrospinning process were studied to elucidate the most effective conditions to create our multifunctional nanofibrous fabrics with smooth fibre morphology (diameters in the range 800–1300 nm) and low bead formation. Our CSFs were shown to degrade in saline buffer solution (pH 7.4) and were readily rendered with anti-bacterial properties against Staphylococcus aureus and Escherichia coli by the post-spinning deposition of silver nanoparticles (AgNPs, 40 nm diameter) or cinnamon essential oil (CEO). The fibres were non-toxic to normal human dermal fibroblast cell lines, as the cells were shown to attach and proliferate on CSFs, CSF/AgNPs and CSF/CEO with good cell tolerance for 72 h of incubation. These smart multifunctional CSFs show great potential towards smart delivery fabrics/dressings capable of carrying water-soluble bioactive agents surrounded by a protective, but degradable, antibacterial shell to guard the cargo for more effective controlled release

Tailoring Hydrogel Sheet Properties through Co-Monomer Selection in AMPS Copolymer Macromers

This study investigates hydrogels based on 2-Acrylamido-2-methyl-1-propanesulfonic acid sodium salt (AMPS) copolymers, incorporating N-hydroxyethyl acrylamide (HEA) and 3-sulfopropyl acrylate potassium salt (SPA). The addition of HEA and SPA is designed to fine-tune the hydrogels’ water absorption and mechanical properties, ultimately enhancing their characteristics and expanding their potential for biomedical applications. A copolymer of AMPS, 2-carboxyethyl acrylate (CEA) combined with methacrylic acid (MAA) as poly(AMPS-stat-CEA-stat-MAA, PACM), was preliminarily synthesized. CEA and MAA were modified with allyl glycidyl ether (AGE) through ring-opening, yielding macromers with pendant allyl groups (PACM-AGE). Copolymers poly(AMPS-stat-HEA-stat-CEA-stat-MAA) (PAHCM) and poly(AMPS-stat-SPA-stat-CEA-stat-MAA) (PASCM) were also synthesized and modified with AGE to produce PAHCM-AGE and PASCM-AGE macromers. These copolymers and macromers were characterized by 1H NMR, FT-IR, and GPC, confirming successful synthesis and functionalization. The macromers were then photocrosslinked into hydrogels and evaluated for swelling, water content, and mechanical properties. The results revealed that the PASCM-AGE hydrogels exhibited superior swelling ratios and water retention, achieving equilibrium water content (~92%) within 30 min. While the mechanical properties of HEA and SPA containing hydrogels show significant differences compared to PACM-AGE hydrogel (tensile strength 2.5 MPa, elongation 47%), HEA containing PAHCM-AGE has a higher tensile strength (5.8 MPa) but lower elongation (19%). In contrast, SPA in the PASCM-AGE hydrogels led to both higher tensile strength (3.7 MPa) and greater elongation (92%), allowing for a broader range of hydrogel properties. An initial study on drug delivery behavior was conducted using PACM-AGE hydrogels loaded with photosensitizers, showing effective absorption, release, and antibacterial activity under light exposure. These AMPS-based macromers with HEA and SPA modifications demonstrate enhanced properties, making them promising for wound management and drug delivery applications

Bioactive Nanocomposites for Tissue Repair and Regeneration: A Review

This review presents scientific findings concerning the use of bioactive nanocomposites in the field of tissue repair and regeneration. Bioactivity is the ability of a material to incite a specific biological reaction, usually at the boundary of the material. Nanocomposites have been shown to be ideal bioactive materials due the many biological interfaces and structures operating at the nanoscale. This has resulted in many researchers investigating nanocomposites for use in bioapplications. Nanocomposites encompass a number of different structures, incorporating organic-inorganic, inorganic-inorganic and bioinorganic nanomaterials and based upon ceramic, metallic or polymeric materials. This enables a wide range of properties to be incorporated into nanocomposite materials, such as magnetic properties, MR imaging contrast or drug delivery, and even a combination of these properties. Much of the classical research was focused on bone regeneration, however, recent advances have enabled further use in soft tissue body sites too. Despite recent technological advances, more research is needed to further understand the long-term biocompatibility impact of the use of nanoparticles within the human body

Characterization and Performance Analysis of Hydrolyzed versus Non-Hydrolyzed Poly(NVF-co-HEA) Hydrogels for Cosmetic Applications

This study explores the synthesis and modification of poly(N-vinylformamide-co-N-hydroxyethyl acrylamide) (poly(NVF-co-HEA)) hydrogels for cosmetic applications. Poly(NVF-co-HEA) hydrogels were produced followed by an acid hydrolysis reaction to produce poly(NVF-co-VAm-co-HEA) hydrogels, introducing poly(vinyl amine) (PVAm) into the structure. This modification considerably alters the hydrogels’ properties, yielding materials with over 96% water content, predominantly in the form of non-freezing or free water, which is beneficial in the uptake and release of hydrophilic species. The primary amine groups from inclusion of VAm also improved the mechanical properties, as evidenced by an 8-fold increase in Young’s modulus. The hydrogels also possessed pH-responsive behavior, which was particularly noticeable under acidic and basic conditions, where a large decrease in water content was observed (40% to 75% reduction). Characterizing the hydrogels’ release capabilities involved using organic dyes of different functional groups and sizes to examine the pH impact on release. The results indicated that hydrolyzed hydrogels interacted more effectively with charged species, highlighting their suitability for pH-responsive delivery. The release of cosmetic active ingredients was also demonstrated through the controlled release of Liquid Azelaic™, specifically potassium azeloyl diglycinate (PAD). Our findings reveal that the hydrolyzed hydrogels exhibit superior burst release, especially under alkaline conditions, suggesting their suitability for cosmetic applications where controlled, pH-responsive delivery of active ingredients is desired. Overall, this investigation highlights the potential of hydrolyzed poly(NVF-co-HEA) hydrogels in cosmetic applications. Their ability to combine high water content with mechanical integrity, along with their pH-responsive release ability, allows for use in cosmetic formulations

The role of stearic acid for silver nanoparticle formation on graphene and its composite with poly(lactic acid)

Graphene-based polymer nanocomposites have received much attention in the field of new hybrid materials, and in the enhancement of properties and diversification of applications. In this work, reduced graphene (rGO) and silver nanoparticles (AgNPs) were cooperated with poly(lactic acid) (PLA) (a semi-crystalline and brittle polymer) to improve mechanical strength and conductivity of the composites. The effect of various concentrations of stearic acid (SA-a precursor) on the formation of silver nanoparticles on graphene and its composite with PLA was studied for the first time. The rGO and AgNPs were first prepared using SA to enhance the AgNPs formation and improve surface wetting of rGO/AgNPs in PLA. The XPS atomic concentration of AgNPs in rGO-Ag-SA1 composite (1:1 mass ratio of SA: graphene oxide) was 5.77%, while, 2.55% in the rGO-Ag composite without SA. This enhancement is due to substitution of AgNPs onto the epoxy and hydroxyl groups on the graphene sheet. In addition, tensile strength of PLA-rGO-AgNPs-SA was higher than neat PLA when AgNPs and SA were added into the composites, especially the composite of PLA-rGO-Ag-SA1 which showed the highest strength increase of 47%. The volume resistivity of PLA-rGO-Ag-SA1 film was also two times lower than PLA-rGO-Ag; thus, this graphene-based composite of PLA-rGO-Ag showed a significant advantage for applications where antistatic properties are required along with an improvement of PLA\u27s tensile strength

Bio-derived and biocompatible poly(lactic acid)/silk sericin nanogels and their incorporation within poly(lactide-co-glycolide) electrospun nanofibers

Bio-derived and biocompatible nanogels based on poly(lactic acid) (PLA) and silk sericin (SS) have been synthesized for the first time. Low molecular weight PLA and SS were first modified using allyl glycidyl ether to create a PLA macromonomer and an SS multifunctional crosslinker (PLAM and SSC, respectively), as confirmed by NMR and FTIR spectroscopies. Nanogels were synthesized from PLAM/SSC and N′,N-methylene bisacrylamide (N′,N-mBAAm) as an additional bifunctional crosslinker via classical free-radical polymerization at systematically varied levels of additional crosslinking (0, 0.5, 1.0, 1.5 and 2.0 w/w% N′,N-mBAAm). Higher crosslink densities led to smaller nanogel particles with reduced accumulative drug release. Crosslinked PLAM/SSC nanogels at 0.5% N′,N-mBAAm with 400–500 nm diameter particles were shown to be non-toxic to the normal human skin fibroblast cell line (NHSF) and selected for incorporation within poly(lactide-co-glycolide) (PLGA) electrospun nanofibers. These embedded nanogel-PLGA nanofibers were non-toxic to the NHSF cell line and exhibited higher cell proliferation than pure PLGA nanofibers, due to their higher hydrophilicity induced by the PLAM/SSC nanogels. This work shows that our new crosslinked-PLAM/SSC nanogels have potential for use not only in the field of drug delivery but also for tissue regeneration by embedding them within nanofibers to create hybrid scaffolds

Green fabrication route of robust, biodegradable silk sericin and poly(vinyl alcohol) nanofibrous scaffolds

Silk sericin (SS) has been extensively used to fabricate scaffolds for tissue engineering. However, due to its inferior mechanical properties, it has been found to be a poor choice of material when being electrospun into nanofibrous scaffolds. Here, SS has been combined with poly(vinyl alcohol) (PVA) and electrospun to create scaffolds with enhanced physical properties. Crucially, these SS/PVA nanofibrous scaffolds were created using only distilled water as a solvent with no added crosslinker in an environmentally friendly process. Temperature has been shown to have a marked effect on the formation of the SS sol–gel transition and thus influence the final formation of fibers. Heating the spinning solutions to 70 °C delivered nanofibers with enhanced morphology, water stability and mechanical properties. This is due to the transition of SS from β-sheets into random coils that enables enhanced molecular interactions between SS and PVA. The most applicable SS/PVA weight ratios for the formation of nanofibers with the desired properties were found to be 7.5/1.5 and 10.0/1.5. The fibers had diameters ranging from 60 to 500 nm, where higher PVA and SS concentrations promoted larger diameters. The crystallinity within the fibers could be controlled by manipulation of the balance between PVA and SS loadings. In vitro degradation (in phosphate buffer solution, pH 7.4 at 37 °C) was 30–50% within 42 days and fibers were shown to be nontoxic to skin fibroblast cells. This work demonstrates a new green route for incorporating SS into nanofibrous fabrics, with potential use in biomedical applications