Evaluation of biological and cytocompatible properties in nano silver-clay based polyethylene nanocomposites.

Nano-toxicological evaluation of a biomaterial is of primordial importance for application in therapeutics. This is one of first reports on systematic analysis of in vitro and in vivo cytocompatible properties of an antimicrobial polyethylene/silver-clay hybrid nanocomposite. The polymeric nanocomposite has been prepared using melt compounding route by a twin screw extruder with silver-clay hybrid content varying from 1 to 5 wt%. The morphology of the polyethylene/silver-clay nanocomposites was investigated using a combination of TEM and XRD techniques. The antimicrobial studies suggest strong biocidal action against E. coli, S. aureus and A. niger. In vitro cytocompatibility studies show excellent compatibility with human erythrocytes and dermal fibroblast cell lines, as compared to powder form silver-clay hybrids which demonstrated mild toxicity. Histopathological analysis of skin tissues excised from rats surgically stitched with nanocomposite film show no morphological change following 21 days of exposure. The developed nanocomposites show excellent antimicrobial activity coupled with cytocompatibility and are hence potential candidates for biomedical applications.

Antimicrobial performance of polyethylene nanocomposite monofilaments reinforced with metal nanoparticles decorated montmorillonite.

A comparative study on the antimicrobial behavior of high density polyethylene (HDPE) nanocomposite monofilaments based on three types of metal nanoparticles (NPs) decorated montmorillonite (MMT) has been presented. Modified MMT decorated with silver, copper and zinc oxide nanoparticles were synthesized in-lab and used as a reinforcing agent in preparing HDPE/modified MMT nanocomposite monofilaments via melt compounding and fiber spinning route in presence of compatibilizer. The concentration of modified MMT was varied from 1 to 5 wt. % in the nanocomposite monofilament. A mixture of intercalated and exfoliated morphology was observed from TEM and WAXD analyses with absence of clay agglomerations. DSC studies indicated MMT acting as heterogeneous nucleating agent with increased degree of crystallinity, crystallization temperature and rate of crystallization. The HDPE/modified MMT nanocomposite monofilaments showed remarkable decrease in bacterial colonies against Gram (-) E. coli and Gram (+) S. aureus with HDPE/Ag-MMT monofilaments showing the highest activity (>99%). The dissolution kinetics of metal ions/NPs from modified MMT nanostructure was studied to understand its effect on antimicrobial action. The antimicrobial filaments are potential candidates to replace neat HDPE counterparts in moist environment applications such as ropes, sacks, agricultural items and geotextiles where microbial growth is a cause of concern.

Antimicrobial and toxicological behavior of montmorillonite immobilized metal nanoparticles.

With increasing demand for novel and potent antimicrobial agents to combat cross-infections and infectious diseases, silver and copper based nanoparticles (NPs) deposited over supports such as montmorillonite (MMT) are playing a crucial role in shaping the current research scenario. Although materials based on Ag NP and Cu NP on MMT have been reported, its toxicological properties on human cell lines have not been accounted for. This paper reports a comparative study on synthesis, antibacterial, antifungal and toxicological behavior of Ag and Cu NPs deposited over MMT nanosheets synthesized by employment of different reduction media. The effect of synthesized NP-MMT hybrids on human erythrocytes and fibroblast cells has been evaluated. The NP formation was facilitated using borohydride and ethyl alcohol (wet chemical route) and photo-reduction and thermal treatment (physical reduction route). The NP-MMT hybrids showed NP formation over supporting silicate layers with particle size ~10-50 nm confirmed by TEM micrographs and loading of ~6-22 wt% of metallic element by EDX analysis. The MMT layers were peeled apart to accommodate NPs inside its galleries, confirmed by increased d-value in powder WAXD. The NP-hybrids showed excellent inhibition zone against bacteria E.coli and S. aureus and fungi A. niger. RBC hemolysis and cytocompatibility assay were performed in vitro to advocate its safety to live human cells. These hybrid materials are potential candidates for new generation advanced antimicrobial materials with less toxicity and highly potent behavior.

A solvent induced crystallisation method to imbue bioactive ingredients of neem oil into the compact structure of poly (ethylene terephthalate) polyester.

Neem oil, a natural antibacterial agent from neem tree (Azadarichtaindica) has been used to impart antibacterial activity to polyester fabrics. Solvent induced polymer modification method was used and that facilitated the easy entry of neem molecules into the compact structure of polyethylene terephthalate (PET) polyester. The polyester fabric was treated with trichloroacetic acid-methylene chloride (TCAMC) solvent system at room temperature prior to treatment with neem oil. The concentration of TCAMC and the treatment time were optimised. XRD and SEM results showed that the TCAMC treatment causes polymer modification and morphological changes in the PET polyester. Antibacterial activity of TCAMC pre-treated and neem-oil-treated polyester fabric was tested using AATCC qualitative and quantitative methods. Both Gram-positive and Gram-negative organisms were used to determine the antimicrobial activity. It was observed that the treated fabric registers substantial antimicrobial activity against both the Staphylococcus aureus (Gram-positive) and the Escherichia coli (Gram-negative) and the effect increases with the increase in concentration of TCAMC treatment. The antibacterial effect remains substantial even after 25 launderings. A kinetic growth study involving the effect of antibacterial activity at various incubation times was carried out.

Advances in topical drug delivery system: micro to nanofibrous structures.

This paper is a review of the latest developments in the field of topical drug delivery via which the drug is directly applied onto the skin with high selectivity and efficiency. Advances in microfiber-based medical textiles such as sutures and wound dressings, especially those containing a drug or an antimicrobial agent, have been covered briefly. A special focus is on recent developments in the area of nanofibrous drug delivery systems, which have several advantages due to their large surface area to volume ratio, high porosity and flexibility. The electrospinning technique to produce nanofibers has also been discussed with reference to latest advances such as multiple needles, needleless and coaxial forms of electrospinning. The applications of nanofibers in different areas such as wound dressing, periodontal and anticancer treatment have also been discussed.

Single-walled carbon nanotube incorporated novel three phase carbon/epoxy composite with enhanced properties.

In the present work, single-walled carbon nanotubes were dispersed within the matrix of carbon fabric reinforced epoxy composites in order to develop novel three phase carbon/epoxy/single-walled carbon nanotube composites. A combination of ultrasonication and high speed mechanical stirring at 2000 rpm was used to uniformly disperse carbon nanotubes in the epoxy resin. The state of carbon nanotube dispersion in the epoxy resin and within the nanocomposites was characterized with the help of optical microscopy and atomic force microscopy. Pure carbon/epoxy and three phase composites were characterized for mechanical properties (tensile and compressive) as well as for thermal and electrical conductivity. Fracture surfaces of composites after tensile test were also studied in order to investigate the effect of dispersed carbon nanotubes on the failure behavior of composites. Dispersion of only 0.1 wt% nanotubes in the matrix led to improvements of 95% in Young's modulus, 31% in tensile strength, 76% in compressive modulus and 41% in compressive strength of carbon/epoxy composites. In addition to that, electrical and thermal conductivity also improved significantly with addition of carbon nanotubes.

Nurses' health education program in India increases HIV knowledge and reduces fear.

Few health care facilities are adequately prepared to manage and care for HIV/AIDS patients in India. Nurses play a critical role in patient care but are often ill-equipped to deal with their own fears of occupational risk and handle the clinical aspects of HIV/AIDS care, leading to stigma and discrimination toward HIV-positive patients. The authors examine the impact of a 4-day HIV/AIDS health education program on knowledge and attitudes of nurses in a government hospital. This education program was developed using a training of trainers model and qualitative research. A total of 21 master trainers underwent 6 days of training and began training of 552 hospital nurses (in 2004-2005). Using a pretest-posttest design, the authors assessed changes in knowledge and attitudes of 371 trained nurses. Significant improvements were seen in nurses' HIV/AIDS knowledge in all areas including care, treatment, and issues of confidentiality and consent. Fear of interaction with people living with HIV/AIDS was reduced significantly. The short course was successful in increasing nurses' knowledge in all aspects. There is great potential to expand this stigma-reduction intervention to other public and private hospitals.

Effect of heterocyclic based organoclays on the properties of polyimide-clay nanocomposites.

Polyimide-clay nanocomposites were prepared from their precursor, namely, polyamic acid, by the solution-casting method. Organomodified montmorillonite (MMT) clay was prepared by treating Na+MMT (Kunipia F) with three different intercalating agents, namely, piperazine dihydrochloride, 1,3-bis(4-piperidinylpropane) dihydrochloride and 4,4'-bipiperidine dihydrochloride at 80 degrees C. Polyamic acid solutions containing various weight percentages of organomodified MMT were prepared by reacting 4,4'-(1,1'-biphenyl-4,4'-diyldioxy)dianiline with bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride in N-methyl-2-pyrrolidinone containing dispersed particles of organomodified MMT at 20 degrees C. Nanocomposite films were prepared from these solutions by solution casting and heated subsequently at a programmed heating rate. These films were transparent and brown in color. The extent of layer separation in nanocomposite films depends upon the chemical structure of the organoclay. These films were characterized by inherent viscosity, FT-IR, DSC, TMA, WAXD, TEM, UV, and TGA. The tensile behavior and surface energy studies were also investigated. The nanocomposite films had superior tensile properties, thermal behavior, and solvent resistance. Among the three organoclays, piperazine dihydrochloride was the best modifier.