Antibacterial, biocompatible, hemostatic, and tissue adhesive hydrogels based on fungal-derived carboxymethyl chitosan-reduced graphene oxide-polydopamine for wound healing applications.

In this study, we developed biocompatible, fungus-derived carboxymethyl chitosan (FCMCS)-reduced graphene oxide (rGO)-polydopamine (PDA)-polyacrylamide (PAM) (FC-rGO-PDA) hydrogels with excellent antibacterial, hemostatic, and tissue adhesive properties for wound healing applications. FC-rGO-PDA hydrogels were prepared by the alkali-induced polymerization of DA followed by the incorporation of GO and its reduction during the polymerization AM to form a homogeneously dispersed PAM network structure in FCMCS solution. The formation of rGO was verified using UV-Vis spectra. The physicochemical properties of hydrogels were characterized by FTIR, and SEM, water contact angle measurements, and compressive studies. SEM and contact angle measurements showed that hydrogels were hydrophilic with interconnected pores and a fibrous topology. In addition, hydrogels adhered well to porcine skin with an adhesion strength of 32.6 ± 1.3 kPa, . The hydrogels exhibited viscoelastic, good compressive (77.5 kPa), swelling, and biodegradation properties. An in vitro study using skin fibroblasts and keratinocytes cells showed the hydrogel had good biocompatibility. Testing against two model bacteria, viz. Staphylococcus aureus and E. coli revealed that the FC-rGO-PDA hydrogel has antibacterial activity. Furthermore, the hydrogel exhibited hemostasis properties. Overall, the developed FC-rGO-PDA hydrogel has antibacterial and hemostasis properties, high water holding capacity, and excellent tissue adhesive properties, which make it a promising candidate for wound healing applications.

Strychnos Potatorum L. Seed Polysaccharide-Based Stimuli-Responsive Hydrogels and Their Silver Nanocomposites for the Controlled Release of Chemotherapeutics and Antimicrobial Applications.

Natural Strychnos potatorum L. (SPL) polysaccharide-based dual-responsive semi-IPN-type (SPL-DMA) hydrogels have been fabricated using dimethylaminoethyl methacrylate by simple free radical polymerization. Furthermore, a facial and eco-friendly method has been developed for the green synthesis of silver nanoparticles on SPL-DMA hydrogel templates (SPL-DMA-Ag) using an aqueous leaf extract of Carissa spinarum (as a bioreducing agent). SPL-DMA and SPL-DMA-Ag were characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), and evaluated network parameters. 5-Fluorouracil and doxorubicin were successfully encapsulated, and in vitro drug release studies were performed at pH values of 1.2 and 7.4 and at 25 and 37 °C. To understand the drug release mechanism of SPL-DMA hydrogels, various kinetic parameters were calculated. Biocompatibility and anticancer activities of SPL-DMA hydrogels were proved by an antioxidant activity study and in vitro cell viability studies against HeLa and 3T3-L1 cell lines. SPL-DMA-Ag hydrogels were used for antibacterial application.

Revised Manuscript with Corrections: Polyurethane-Based Conductive Composites: From Synthesis to Applications.

The purpose of this review article is to outline the extended applications of polyurethane (PU)-based nanocomposites incorporated with conductive polymeric particles as well as to condense an outline on the chemistry and fabrication of polyurethanes (PUs). Additionally, we discuss related research trends of PU-based conducting materials for EMI shielding, sensors, coating, films, and foams, in particular those from the past 10 years. PU is generally an electrical insulator and behaves as a dielectric material. The electrical conductivity of PU is imparted by the addition of metal nanoparticles, and increases with the enhancing aspect ratio and ordering in structure, as happens in the case of conducting polymer fibrils or reduced graphene oxide (rGO). Nanocomposites with good electrical conductivity exhibit noticeable changes based on the remarkable electric properties of nanomaterials such as graphene, RGO, and multi-walled carbon nanotubes (MWCNTs). Recently, conducting polymers, including PANI, PPY, PTh, and their derivatives, have been popularly engaged as incorporated fillers into PU substrates. This review also discusses additional challenges and future-oriented perspectives combined with here-and-now practicableness.

Synthesis of Novel Tamarind Gum-co-poly(acrylamidoglycolic acid)-Based pH Responsive Semi-IPN Hydrogels and Their Ag Nanocomposites for Controlled Release of Chemotherapeutics and Inactivation of Multi-Drug-Resistant Bacteria.

In this paper, novel pH-responsive, semi-interpenetrating polymer hydrogels based on tamarind gum-co-poly(acrylamidoglycolic acid) (TMGA) polymers were synthesized using simple free radical polymerization in the presence of bis[2-(methacryloyloxy)ethyl] phosphate as a crosslinker and potassium persulfate as a initiator. In addition, these hydrogels were used as templates for the green synthesis of silver nanoparticles (13.4 ± 3.6 nm in diameter, TMGA-Ag) by using leaf extract of Teminalia bellirica as a reducing agent. Swelling kinetics and the equilibrium swelling behavior of the TMGA hydrogels were investigated in various pH environments, and the maximum % of equilibrium swelling behavior observed was 2882 ± 1.2. The synthesized hydrogels and silver nanocomposites were characterized via UV, FTIR, XRD, SEM and TEM. TMGA and TMGA-Ag hydrogels were investigated to study the characteristics of drug delivery and antimicrobial study. Doxorubicin hydrochloride, a chemotherapeutic agent successfully encapsulated with maximum encapsulation efficiency, i.e., 69.20 ± 1.2, was used in in vitro release studies in pH physiological and gastric environments at 37 °C. The drug release behavior was examined with kinetic models such as zero-order, first-order, Higuchi, Hixson Crowell and Korsmeyer-Peppas. These release data were best fitted with the Korsemeyer-Peppas transport mechanism, with n = 0.91. The effects of treatment on HCT116 human colon cancer cells were assessed via cell viability and cell cycle analysis. The antimicrobial activity of TMGA-Ag hydrogels was studied against Staphylococcus aureus and Klebsiella pneumonia. Finally, the results demonstrate that TMGA and TMGA-Ag are promising candidates for anti-cancer drug delivery and the inactivation of pathogenic bacteria, respectively.

Preparation of Waterborne Polyurethane-Based Macroporous Sponges as Wound Dressings.

Recently, eco-friendly and biologically harmless products of waterborne polyurethane (WPU) instead of solvent-borne polyurethane have been strongly progressed in both industries and research areas. Accordingly, we developed a WPU-based macroporous sponge as a skin tissue engineering matrix. Also, the WPU dispersion in water was modified by using a foaming agent in order to create creamy emulsion resulting in enlarging surface area wherein cells could adhere, grow, and proliferate. We investigated the effect of a foaming agent on the morphology of surface and internal structure, wettability. In vitro studies also confirmed enhanced adherence and proliferation of cells with increased metabolic rate. These results proved that the use of foaming agent could alter the internal structure, surface property, and biocompatibility.

Synthesis and Characterization of Carboxymethyl Chitosan Scaffolds Grafted with Waterborne Polyurethane.

Bone tissue engineering has been rapidly developed in regenerative medicine field, which aims to induce new functional bone regeneration through the synergistic combination of biomaterials and cells. Porous biomaterials with sufficient mechanical properties and functional impregnating for bone substitutes have been imposed in the oncoming generation of bone reconstruction. In this study, we fabricated Carboxymethyl chitosan three dimensional (3D) porous scaffold modified with waterborne polyurethane (WPU) through freeze drying technique. In order to check its potential in bone tissue substitutes, osteoblast cells (hFOB 1.19) were seeded onto the fabricated scaffolds and then, SEM and proliferation assay were performed. The enhanced proliferation was contributed to 3D macroporous network structure, large surface area, and osteoconductive environments.

One-pot synthesis of ZnO nanobelt-like structures in hyaluronan hydrogels for wound dressing applications.

In this study, hyaluronic acid-zinc oxide ((HA-ZnO) nanocomposite hydrogels (NCHs) were prepared by one-pot synthesis method. In particular, one-pot process facilitated the rapid formation of a network structure of HA hydrogel with 1,4-butanediol diglycidyl ether (BDDE) crosslinker followed by the formation of ZnO nanobelt-like structures, which was confirmed using 1H NMR, FTIR, XRD, and SEM techniques. The rheology, swelling, and biodegradable behavior were assessed. The cell proliferation and adhesion were retained (similar to HA hydrogels) after the incorporation of ZnO in the hydrogels treated with Human Skin Fibroblasts (CCD-986k). An examination of the hemostatic property of the hydrogels confirmed the good hemostatic properties of HA-ZnO NCHs. An antibacterial study against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli bacteria revealed their excellent antibacterial efficacy. However, the antiadhesive bacterial property of HA hydrogels was slightly reduced with the incorporation of ZnO. In summary, one-pot synthesis of ZnO nanobelt-like structures in HA hydrogels may be excellent candidates for cell adhesive, hemostatic, and antibacterial materials for wound dressing applications.

Synthesis of composite gelatin-hyaluronic acid-alginate porous scaffold and evaluation for in vitro stem cell growth and in vivo tissue integration.

Engineering three-dimensional (3-D) porous scaffolds with precise bio-functional properties is one of the most important issues in tissue engineering. In the present study, a three-dimensional gelatin-hyaluronic acid-alginate (GHA) polymeric composite was synthesized by freeze-drying, which was followed by ionic crosslinking using CaCl2, and evaluated for its suitability in bone tissue engineering applications. The obtained matrix showed high porosity (85%), an interconnected pore morphology and a rapid swelling behavior. The rheological analysis of GHA showed a viscoelastic characteristic, which suggested a high load bearing capacity without fractural deformation. The influence of the GHA matrix on cell growth and on modulating the differentiation ability of mesenchymal stem cells was evaluated by different biochemical and immunostaining assays. The monitoring of cells over a period of four weeks showed increased cellular proliferation and osteogenic differentiation without external growth factors, compared with control (supplemented with osteogenic differentiation medium). The in vivo matrix implantation showed higher matrix-tissue integration and cell infiltration as the duration of the implant increased. These results suggest that a porous GHA matrix with suitable mechanical integrity and tissue compatibility is a promising substrate for the osteogenic differentiation of stem cells for bone tissue engineering applications.

Nano-biomimetics for nano/micro tissue regeneration.

Nanostructured biomimetics have recently shown great promise in the field of tissue engineering. They can be used as nanoscaffolds and tailored at the molecular level. The scaffold topography closely resembles the native extracellular matrix in terms of framing, porosity and bio-functionality. This review covers the approaches used for biomimetic fabrication, including soft lithography, the plasmonic nanohybrid matrix method and multilayer self-assembly scaffolds for tissue regeneration. It brings together knowledge from different arenas about the synthesis, characterization and functionalization of matrices to accelerate the tissue regeneration process. Every tissue in the body presents different challenges and requires a specific fabrication process designed to identify and mirror the particular organ. For example, microfluidics systems aim to mimic the extracellular matrix of vascular and cartilage tissue, and these systems have different parts with completely different mechanical strength, cellular adhesion and interplay between matrix and cells. A fully functional nanomatrix designed by a self-assembling methodology for use as a vascular tissue engineering scaffold needs to have intrinsic microvessels that facilitate the transportation of metabolites and nutrients. Similarly, in the case of peripheral nerve regeneration, a scaffold needs to have sufficient mechanical strength to protect the regenerating tissue, yet be biodegradable enough to avoid a possible second surgery. To enhance the functionality of scaffolds, increasing focus has been placed on in vitro and in vivo research to achieve optimal scaffold design. Nanobiomimetics unarguably offer the most suitable physicochemical scaffold properties for tissue regeneration.