M. Selvakumar

Novel CuO/chitosan nanocomposite thin film: facile hand-picking recoverable, efficient and reusable heterogeneous photocatalyst

The present work demonstrates a new simple hand-picking technique for the 100% recovery of a photocatalyst. CuO nanospheres were synthesized by a simple wet chemical method and were subsequently embedded into the biopolymer matrix (chitosan) under mild conditions by the solution cast method and its photocatalytic application towards the degradation of organic pollutants was measured for the first time. The crystal structure, optical properties, surface and bulk morphology were discussed in detail. ICP-OES analysis showed 3.025% copper embedded in the chitosan (CS) matrix. Efficiency of the CuO/chitosan was evaluated against the degradation of rhodamine B dye as a probe. The combination of CuO nanospheres with chitosan leads to the higher efficiency of up to 99% degradation of the dye with 60 minutes of irradiation. This may be attributed to many features such as the slow electron hole pair recombination rate of nanosized CuO in the biopolymer matrix, the large surface area of the CuO and the high adsorption efficiency of the chitosan. The major advantage of this present protocol is that it is not only restricted to azo type dyes but can also be adopted for different kinds of organic pollutants. For all the types of organic contaminants tested, the CuO/chitosan nanocomposite thin film photocatalyst showed excellent activity. The facile hand-picking recovery and recyclability of this novel thin film likely opens up a new straightforward strategy in the effective photocatalytic degradation of organic contaminants.

CdO/ZnO nanohybrids: facile synthesis and morphologically enhanced photocatalytic performance

A series of CdO/ZnO nanohybrids of different compositions were synthesized by a wet chemical method and investigated in detail. The nanohybrids were characterized by various techniques such as wide angle X-ray diffraction (XRD), diffuse reflectance UV-vis spectroscopy, transmission electron microscopy (TEM), and field emission scanning electron microscopy (FE-SEM). The results revealed that the crystal structure and optical properties of the nanohybrids were almost the same for all the compositions. FE-SEM images showed that the morphology of CdO/ZnO was hexagonal like microspheres, and the 0.75 : 1 Cd/Zn sample had a well-proportioned morphology. Three different dyes viz crystal violet, congo red and rhodamineB were used for the photocatalytic studies in a photoreactor and monitored with a UV-visible spectrometer. The nanohybrids showed excellent photocatalytic degradation compared to pure CdO and ZnO. In particular, nanohybrids with 0.75 : 1 (Cd : Zn) composition ratio exhibited better results compared to all other CdO/ZnO nanohybrids, which may be attributed to the improved charge separation at the heterojunction interface.

On-Demand Guided Bone Regeneration with Microbial Protection of Ornamented SPU Scaffold with Bismuth-Doped Single Crystalline Hydroxyapatite: Augmentation and Cartilage Formation

Guided bone regeneration (GBR) scaffolds are futile in many clinical applications due to infection problems. In this work, we fabricated GBR with an anti-infective scaffold by ornamenting 2D single crystalline bismuth-doped nanohydroxyapatite (Bi-nHA) rods onto segmented polyurethane (SPU). Bi-nHA with high aspect ratio was prepared without any templates. Subsequently, it was introduced into an unprecedented synthesized SPU matrix based on dual soft segments (PCL-b-PDMS) of poly(ε-caprolactone) (PCL) and poly(dimethylsiloxane) (PDMS), by an in situ technique followed by electrospinning to fabricate scaffolds. For comparison, undoped pristine nHA rods were also ornamented into it. The enzymatic ring-opening polymerization technique was adapted to synthesize soft segments of PCL-b-PDMS copolymers of SPU. Structure elucidation of the synthesized polymers is done by nuclear magnetic resonance spectroscopy. Sparingly, Bi-nHA ornamented scaffolds exhibit tremendous improvement (155%) in the mechanical properties with excellent antimicrobial activity against various human pathogens. After confirmation of high osteoconductivity, improved biodegradation, and excellent biocompatibility against osteoblast cells (in vitro), the scaffolds were implanted in rabbits by subcutaneous and intraosseous (tibial) sites. Various histological sections reveal the signatures of early cartilage formation, endochondral ossification, and rapid bone healing at 4 weeks of the critical defects filled with ornamented scaffold compared to SPU scaffold. This implies osteogenic potential and ability to provide an adequate biomimetic microenvironment for mineralization for GBR of the scaffolds. Organ toxicity studies further confirm that no tissue architecture abnormalities were observed in hepatic, cardiac, and renal tissue sections. This finding manifests the feasibility of fabricating a mechanically adequate nanofibrous SPU scaffold by a biomimetic strategy and the advantages of Bi-nHA ornamentation in promoting osteoblast phenotype progression with microbial protection (on-demand) for GBR applications.

Excavating the Role of Aloe Vera Wrapped Mesoporous Hydroxyapatite Frame Ornamentation in Newly Architectured Polyurethane Scaffolds for Osteogenesis and Guided Bone Regeneration with Microbial Protection

Guided bone regeneration (GBR) scaffolds are unsuccessful in many clinical applications due to a high incidence of postoperative infection. The objective of this work is to fabricate GBR with an anti-infective electrospun scaffold by ornamenting segmented polyurethane (SPU) with two-dimensional Aloe vera wrapped mesoporous hydroxyapatite (Al-mHA) nanorods. The antimicrobial characteristic of the scaffold has been retrieved from the prepared Al-mHA frame with high aspect ratio (∼14.2) via biosynthesis route using Aloe vera (Aloe barbadensis miller) extract. The Al-mHA frame was introduced into an unprecedented SPU matrix (solution polymerized) based on combinatorial soft segments of poly(ε-caprolactone) (PCL), poly(ethylene carbonate) (PEC), and poly(dimethylsiloxane) (PDMS), by an in situ technique followed by electrospinning to fabricate scaffolds. For comparison, pristine mHA nanorods are also ornamented into it. An enzymatic ring-opening polymerization technique was adapted to synthesize soft segment of (PCL-PEC-b-PDMS). Structure elucidation of the synthesized polymers is established by nuclear magnetic resonance spectroscopy. Sparingly, Al-mHA ornamented scaffolds exhibit tremendous improvement (175%) in the mechanical properties with promising antimicrobial activity against various human pathogens. After confirmation of high osteoconductivity, improved biodegradation, and excellent biocompatibility against osteoblast-like MG63 cells (in vitro), the scaffolds were implanted in rabbits as an animal model by subcutaneous and intraosseous (tibial) sites. Improved in vivo biocompatibilities, biodegradation, osteoconductivity, and the ability to provide an adequate biomimetic environment for biomineralization for GBR of the scaffolds (SPU and ornamented SPUs) have been found from the various histological sections. Early cartilage formation, endochondral ossification, and rapid bone healing at 4 weeks were found in the defects filled with Al-mHA ornamented scaffold compared to pristine SPU scaffold. Organ toxicity studies further confirm the absence of appreciable tissue architecture abnormalities in the renal hepatic and cardiac tissue sections. The entire results of this study manifest the feasibility of fabricating a mechanically adequate tailored nanofibrous SPU scaffold based on combinatorial soft segments of PCL, PEC, and PDMS by a biomimetic approach and the advantages of an Aloe vera wrapped mHA frame in promoting osteoblast phenotype progression with microbial protection for potential GBR applications.

Biomaterials based nano-applications of Aloe vera and its perspective: a review

Aloe vera is noted for its meritable medicinal as well as commercial usages. From the past until now, it has been used as a promising remedy for several ailments. Recently, the concept of nanotechnology has astonishingly changed its outlook for biomedical applications. Nanotechnology has revolutionized several fields with its admirable capabilities and ground-breaking innovations. In the field of medicine, nanostructured materials have introduced a great range of flexibility by refashioning traditional practices and also by exploring new effective approaches. Accordingly, the usage of Aloe vera in the form of hydrogels, nanoparticles, nanocomposites, nanofibers and bio-inspired sponges has extended its well established application spectrum in the fields of wound healing, tissue engineering and drug delivery. In addition, the growing interest in consuming and synthesizing materials based on green or eco-friendly methods also highly encourages the use of numerous plant-based natural products including Aloe vera. Hence, an effort has been made to discuss the works related to recent advancements made in the use of Aloe vera, especially in the form of biomaterial-based nanostructures. This will encourage scientists to explore the unplumbed abilities of Aloe vera. Moreover, it will also help the industry players to recognise its immense potential and bring significant Aloe products to the market.

Self-assembly of a biodegradable branched PE-PCL-b-PEC amphiphilic polymer: synthesis, characterization and targeted delivery of doxorubicin to cancer cells

A novel biodegradable branched block copolymer was synthesized by the ring-opening polymerization of ethylene carbonate using pre-synthesized four-armed pentaerythretol poly(e-caprolactone) (PE-PCL) as a macro initiator. Folic acid was conjugated with the end-group of the block copolymer and self-assembled in water to form polymer micelles (PMs). The very low critical micelle concentration of the block copolymer suggests its potential application in advanced drug delivery systems. The PMs are spherical in shape and have an average size of 80 nm, which is suitable for the delivery of drugs. The hydrophobicity of pentaerythretol poly(e-caprolactone) and its branched structure can accommodate high amounts of doxorubicin. Compared with a blank sample, PMs containing encapsulated doxorubicin show a much higher cytotoxicity towards HeLa cells. A high rate of release of doxorubicin in vitro at pH 5.0 shows that the system is responsive to pH. Confocal laser scanning microscopy showed that the doxorubicin-loaded PMs were internalized into the HeLa cells.

Prospects of common biomolecules as coating substances for polymeric biomaterials

Growing demand for ideal materials in biomedical field not only explores novel approaches, but also examines how existing resources can be modified to fit the requirements. This strategy resulted in the development of various surface modification techniques to improve the biocompatibility of materials already in use. Although various methods are available, the concept of using biological substances for improving biocompatibility seems rational and effective because of the bio-friendly surface that they present which is closer to mimicking the innate environment. Some common biomolecules like proteins, lipids, carbohydrates and peptides are extensively applied on material surfaces through innovative mechanisms. This review will help us to keep abreast of the different types of coating methodologies used and the importance of biological substances as coating alternatives for improving the biocompatibility of polymers. Further, it will also encourage the development of these techniques to modernise materials to make them a more putative choice for biomedical applications.

Structure–property relationship of halloysite nanotubes/ethylene–vinyl acetate–carbon monoxide terpolymer nanocomposites

Poly(ethylene-co-vinyl acetate-co-carbon monoxide) (EVACO)/halloysite nanotube (HNT) nanocomposite films were solution cast. Dispersion of HNTs in the matrix was analyzed by elemental mapping and the role of HNTs on crystallizability, flammability and thermal, mechanical, and electrical properties of the polymer was evaluated. The nature of interaction between the EVACO matrix and HNTs was studied using Fourier transform infrared spectroscopy. The highest tensile strength was observed for the composite with 1% filler loading, whereas the highest crystallinity was observed for that with 3% filler loading. The decay in the tensile properties at higher filler loading was due to agglomeration of HNTs and debonding of polymer–filler interface. The electrical volume resistivity of the composites decreased with HNT loading because of the ionic charge transfer. The direct current electrical resistivity study of the composites proves that the addition of HNT can improve the antistatic properties of the polymer.

Hemocompatibility of Sulfuric Acid-Treated Metallocene Polyethylene and its Application in Reducing the Quantity of Medical Plastic Waste

ABSTRACT The hazards of dumping medical plastics have created a huge demand to reduce the quantity of plastic usage without compromising its quality. The metallocene synthesized polyethylene is one such advent, however, its clinical usage is limited by the problem of hemocompatibility. This study investigates the effect of sulfuric acid-induced changes in metallocene polyethylene. Fourier transform infrared spectroscopy analysis illustrated the addition of OH and sulfonic acid group, which subsequently increased the wettability. An improvement in micro as well as nanosurface roughness was observed. Ultimately, the treated surfaces depicted delayed clotting time, adsorption of specific plasma proteins, reduced hemolysis, and resistance against platelet adhesion. GRAPHICAL ABSTRACT