Nandakumar Kalarikkal

Electrospun polycaprolactone/ZnO nanocomposite membranes as biomaterials with antibacterial and cell adhesion properties

In the present study we have investigated the effect of zinc oxide (ZnO) nanoparticles on the fiber diameter, fiber morphology, antibacterial activity, and enhanced cell proliferation of the electrospun polycaprolactone (PCL) non-woven membrane. The effect of the ZnO nanoparticle concentration on the fiber diameter and fiber morphology was investigated using a scanning electron microscope (SEM). Fourier transform infrared spectroscopy (FT-IR) analysis was carried out to determine the nature of the interaction between the PCL and the ZnO nanoparticles. We also investigated the mechanical stability and antibacterial activity of the fabricated material. Interestingly, the membranes with ZnO nanoparticles showed enhanced mechanical stability, antibacterial properties, fibroblast proliferation, and improved metabolic activity of the cells. Further, this is the first report regarding the ability of a biomaterial containing ZnO nanoparticles to enhance cell proliferation.

Electrospun polycaprolactone membranes incorporated with ZnO nanoparticles as skin substitutes with enhanced fibroblast proliferation and wound healing

ZnO nanoparticles are well known for their ability to generate Reactive Oxygen Species (ROS) which have a potential role in biological systems. ROS can enhance wound healing by improved cell adhesion and cell migration through growth factor mediated pathways. Here we report the fabrication of electrospun polycaprolactone scaffolds incorporated with ZnO nanoparticles and their ability to perform as skin substitute materials which promote the healing process. The plain or ZnO nanoparticle incorporated PCL membranes were implanted subcutaneously in guinea pigs. Immunological, macroscopical and histological evaluations have shown that the use of membranes containing ZnO nanoparticles enhances the cell adhesion and migration. The ZnO nanoparticle embedded membranes do not show any significant sign of inflammation. The implant also enhanced the wound healing without any scar formation.

Investigation of angiogenesis and its mechanism using zinc oxide nanoparticle-loaded electrospun tissue engineering scaffolds

Angiogenesis through tissue engineering scaffolds is an important factor that determines the success of a tissue engineering endeavor. Zinc oxide (ZnO) nanoparticles are well known for their ability to generate reactive oxygen species (ROS) which have a potential role in biological systems. ROS can induce angiogenesis through growth factor mediated mechanisms. Here, we report the fabrication of electrospun polycaprolactone scaffolds incorporated with ZnO nanoparticles and their ability to induce angiogenesis. This study demonstrated that the induction of angiogenesis was by the expression of key proangiogenic factors, fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF), upregulated due to the presence of ZnO nanoparticles. This is the first report suggesting the use of a metal/metal oxide nanoparticle in tissue engineering scaffolds to enhance angiogenesis.

Completely green synthesis of dextrose reduced silver nanoparticles, its antimicrobial and sensing properties

We herein report the green synthesis of highly monodispersed, water soluble, stable and smaller sized dextrose reduced gelatin capped-silver nanoparticles (Ag-NPs) via an eco-friendly, completely green method. The synthesis involves the use of silver nitrate, gelatin, dextrose and water as the silver precursor, stabilizing agent, reducing agent and solvent respectively. By varying the reaction time, the temporal evolution of the growth, optical, antimicrobial and sensing properties of the as-synthesised Ag-NPs were investigated. The nanoparticles were characterized using UV-vis absorption spectroscopy, Fourier transform infra-red spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HR-TEM). The absorption maxima of the as-synthesized materials at different reaction time showed characteristic silver surface plasmon resonance (SPR) peak. The as-synthesised Ag-NPs show better antibacterial efficacy than the antibiotics; ciproflaxin and imipenem against Pseudomonas aeruginosa with minimum inhibition concentration (MIC) of 6 μg/mL, and better efficacy than imipenem against Escherichia coli with MIC of 10 μg/mL. The minimum bactericidal concentration (MBC) of the as-synthesised Ag-NPs is 12.5 μg/mL. The sensitivity of the dextrose reduced gelatin-capped Ag-NPs towards hydrogen peroxide indicated that the sensor has a very good sensitivity and a linear response over wide concentration range of 10(-1)-10(-6)M H2O2.

A facile and rapid method for the black pepper leaf mediated green synthesis of silver nanoparticles and the antimicrobial study

Green synthesis of nanoparticles is widely accepted due to the less toxicity in comparison with chemical methods. But there are certain drawbacks like slow formation of nanoparticles, difficulty to control particle size and shape make them less convenient. Here we report a novel cost-effective and eco-friendly method for the rapid green synthesis of silver nanoparticles using leaf extracts of Piper nigrum. Our results suggest that this method can be used for obtaining silver nanoparticles with controllable size within a few minutes. The fabricated nanoparticles possessed excellent antibacterial property against both Gram-positive and Gram-negative bacteria.

Advancement of wound care from grafts to bioengineered smart skin substitutes

This review gives a brief description on the skin and its essential functions, damages or injury which are common to the skin and the role of skin substitute to replace the functions of the skin soon after an injury. Skin substitutes have crucial role in the management of deep dermal and full thickness wounds. At present, there is no skin substitute in the market that can replace all the functions of skin ‘and the research is still continuing for a better alternative. This review is an attempt to recollect and report the past efforts including skin grafting and recent trends like use of bioengineered smart skin substitutes in wound care. Incorporation functional moieties like antimicrobials and wound healing agents are also described.

Electrospun poly(ε-caprolactone)-based skin substitutes: In vivo evaluation of wound healing and the mechanism of cell proliferation.

In the present study, we have fabricated electrospun poly(ε-caprolactone)-based membranes, characterized and studied the in vivo cell migration and proliferation and wound healing activity. Moreover, we did not seed any cells prior to the animal implantation and we could observe excellent fibroblast attachment and cell proliferation. Further full thickness excision wound on guinea pig completely healed within 35 days. We could reach in an assumption that the enhanced cell proliferation and wound healing might be due to the surface degradation of the polymer under physiological conditions and the formation of functional groups like hydroxyl and carboxyl groups that promoted cell proliferation in a cell adhesion protein mediated mechanism. This study is a novel tissue engineering concept for the reconstruction of a damaged tissue without the in vitro cell seeding and proliferation prior to the in vivo implantation.

Effect of zinc oxide nanoparticles on the in vitro degradation of electrospun polycaprolactone membranes in simulated body fluid

ABSTRACT Even though the biodegradability of polycaprolactone (PCL) is well established, few studies have carried out on the effect of nanofillers on the in vitro degradability of electrospun PCL membranes. Thus, the authors incorporated common nanofiller zinc oxide (ZnO) nanoparticles in electrospun PCL membranes. From the study of morphological schanges as well as the changes in crystallinity, it is clear that the ZnO nanoparticles accelerated the degradation of PCL. The FTIR results ascertain that the hydrolysis of the PCL nanofibers generates free hydroxyl and carbonyl groups in the bulk of the polymer. The tensile property of the PCL/ZnO nanocomposite membranes decreased with an increase in filler loading during degradation. GRAPHICAL ABSTRACT

Electrospun PCL membranes incorporated with biosynthesized silver nanoparticles as antibacterial wound dressings

An open wound is highly prone to bacterial colonization and infection. Bacterial barrier property is an important factor that determines the success of a wound coverage material. Apart from the bacterial barrier property, presence of antibacterial agents can successfully eliminate the invasion and colonization of pathogen in the wound. Silver nanoparticles are well-known antimicrobial agents against a wide range of microorganisms. Biosynthesized silver nanoparticles are more acceptable for medical applications due to superior biocompatibility than chemically synthesized ones. Presence of biomolecules on biosynthesized silver nanoparticles enhances its therapeutic efficiency. Polycaprolactone (PCL) is a well-known material for biomedical applications including wound dressings. Electrospinning is an excellent technique for the fabrication of thin membranes for wound coverage applications with barrier property against microbes. In this paper, we report the fabrication and characterization of electrospun PCL membranes incorporated with biosynthesized silver nanoparticles for wound dressing applications.

An in vitro method for the determination of microbial barrier property (MBP) of porous polymeric membranes for skin substitute and wound dressing applications

Barrier property of materials to microbes is an important aspect in many applications like wound dressings and skin substitutes. Lack of a standard method for the evaluation of microbial barrier property limits the consideration of this important aspect by many bioengineers and biomaterial scientists. Thus, in this study we are intended to develop a standard method for the quantitative assessment of Microbial Barrier Property (MBP) and express this in terms of percentage in comparison with a control which resembles a bare wound or a standard existing wound coverage material. In this study, we have evaluated the microbial barrier property of electrospun materials with different pore spaces and our study showed that this method can be successfully used for the assessment of bacterial barrier property of materials intended for wound dressing and skin substitute applications. Further, the results showed that the MBP will vary with the test conditions. This methodology can be used to measure the microbial barrier property of wide range of materials like skin substitute materials, wound dressings, medical textiles and many other materials where microbial prevention is important. This methodology can also be extended to the specific determination of bacterial, fungal or viral barrier property with minor modifications.