Time filter

Source Type

Karunaratne D.N.,University of Peradeniya | Jafari M.,Massachusetts Institute of Technology | Ranatunga R.J.K.U.,University of Peradeniya | Siriwardhana A.,Sri Lanka Institute of Nanotechnology
Current Pharmaceutical Design | Year: 2015

This review is based on carriers of natural origin such as polysaccharides, proteins, and cell derived entities which have been used for delivery of siRNA. To realize the therapeutic potential of a delivery system, the role of the carrier is of utmost importance. Historical aspects of viral vectors, the first carriers of genes are briefly outlined. Chitosan, one of the extensively experimented carriers, alginates and other polysaccharides have shown success in siRNA delivery. Peptides of natural origin and mimics thereof have emerged as another versatile carrier. Exosomes and mini cells of cellular origin are the newest entrants to the area of siRNA delivery and probably the closest one can get to a natural carrier. In many of the carriers, modifications have provided better efficiency in delivery. The salient features of the carriers and their advantages and disadvantages are also reviewed © 2015 Bentham Science Publishers.

Samindra K.M.S.,Institute of Chemistry Ceylon | Kottegoda N.,University of Sri Jayewardenepura | Kottegoda N.,Sri Lanka Institute of Nanotechnology
Nanotechnology Reviews | Year: 2014

This study focuses on the encapsulation of natural curcumin present in turmeric (Curcuma longa L.) into a layered double hydroxide (LDH), which demonstrates slow release properties with future potential in therapeutic applications such as slow release wound dressings. Turmeric has been used in traditional medicinal applications since ancient times. The main active substances in turmeric are curcumin together with two related compounds, demethoxycurcumin (DMC) and bisdemethoxycurcumin (BDMC), which have been extensively studied as antibacterial compounds. However, these molecules are unstable and, therefore, demonstrate limited biological activity and practical applications. In this study, attempts were made to synthesize curcumin in-situ encapsulated layered LDHs in order to stabilize the curcumin molecules within the nanolayers of the LDHs. The curcumin intercalated LDHs were synthesized by a simple in-situ co-precipitation method. The release characteristics of curcumin from the nanocomposites were quantitatively monitored under different pH conditions using UV-Visible spectroscopic methods, and the results indicate that the nanocomposite has the future potential in slow release therapeutic applications.

Fernando M.S.,University of Colombo | De Silva W.R.M.,University of Colombo | De Silva K.M.N.,University of Colombo | De Silva K.M.N.,Sri Lanka Institute of Nanotechnology
International Journal of Nanoscience | Year: 2014

In this study a novel nano composite of hydroxyapatite nano particles impregnated activated carbon (C-HAp), which was synthesized in our own method, was used in iron adsorption studies. The study was conducted in order to investigate the potential of using C-HAp nanocomposite to be used in clinical detoxifications such as acute iron toxicity where the use of Activated carbon (GAC) is not very effective. Adsorption studies were conducted for synthetic solutions of Fe2+, Fe3+ and iron syrup using GAC, C-HAp and neat HAp as adsorbents. According to the results C-HAp nano composite showed improved properties than GAC in adsorbing Fe2+, Fe3+ and also Fe ions in iron syrup solutions. Thus the results of the in-vitro studies of iron adsorption studies indicated the potential of using C-HAp as an alternative to activated carbon in such clinical applications. © 2014 World Scientific Publishing Company.

Manatunga D.C.,Sri Lanka Institute of Nanotechnology | De Silva R.M.,University of Colombo | De Silva K.M.N.,Sri Lanka Institute of Nanotechnology | De Silva K.M.N.,University of Colombo
Applied Surface Science | Year: 2016

Creation of differential superhydrophobicity by applying different non-fluorinated hydrophobization agents on a cotton fabric roughened with silica nanoparticles was studied. Cotton fabric surface has been functionalized with silica nanoparticles and further hydrophobized with different hydrophobic agents such as hexadecyltrimethoxy silane (HDTMS), stearic acid (SA), triethoxyoctyl silane (OTES) and hybrid mixtures of HDTMS/SA and HDTMS/OTES. The cotton fabrics before and after the treatment were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM) and thermogravimetric analysis (TGA). The wetting behavior of cotton samples was investigated by water contact angle (WCA) measurement, water uptake, water repellency and soil repellency testing. The treated fabrics exhibited excellent water repellency and high water contact angles (WCA). When the mixture of two hydrophobization agents such as HDTMS/OTES and HDTMS/SA is used, the water contact angle has increased (145°-160°) compared to systems containing HDTMS, OTES, SA alone (130°-140°). It was also noted that this fabricated double layer (silica + hydrophobization agent) was robust even after applying harsh washing conditions and there is an excellent anti-soiling effect observed over different stains. Therefore superhydrophobic cotton surfaces with high WCA and soil repellency could be obtained with silica and mixture of hydrophobization agents which are cost effective and environmentally friendly when compared with the fluorosilane treatment. © 2015 Elsevier B.V. All rights reserved.

Wijesena R.N.,Sri Lanka Institute of Nanotechnology | Tissera N.,Sri Lanka Institute of Nanotechnology | Kannangara Y.Y.,Sri Lanka Institute of Nanotechnology | Lin Y.,CAS Changchun Institute of Applied Chemistry | And 2 more authors.
Carbohydrate Polymers | Year: 2015

A method of top down preparation of chitosan nanoparticles and nanofibers is proposed. Chitin nanofibrils (chitin NFs) were prepared using ultrasonic assisted method from crab shells with an average diameter of 5 nm and the length less than 3 μm as analyzed by atomic force microscopy and transmission electron microscopy. These chitin nanofibers were used as the precursor material for the preparation of chitosan nanoparticles and nanofibers. The degree of deacetylation of these prepared chitosan nanostructures were found to be approximately 98%. In addition these chitosan nanostructures showed amorphous crystallinity. Transmission electron microscopic studies revealed that chitosan nanoparticles were roughly spherical in nature and had diameters less than 300 nm. These larger particles formed through self-assembly of much smaller 25 nm particles as evidenced by the TEM imaging. The diameter and the length of the chitosan nanofibers were found to be less than 100 nm and 3 μm respectively. It is envisaged that due to the cavitation effect, the deacetylated chitin nanofibers were broken down to small pieces to form seed particles. These seed particles can then be self-assembled to form larger chitosan nanoparticles. © 2014 Elsevier Ltd. All rights reserved.

Wijesena R.N.,Sri Lanka Institute of Nanotechnology | Tissera N.,Sri Lanka Institute of Nanotechnology | Perera R.,Sri Lanka Institute of Nanotechnology | De Silva K.M.N.,Sri Lanka Institute of Nanotechnology
Carbohydrate Polymers | Year: 2014

Chitin nanofibers have been prepared from crab shell as a chitin source using ultrasound assisted fibrillation. Atomic force microscopy (AFM) study showed that the prepared nanofibers were having diameters and lengths primarily in the range of 2-20 nm and 0.3-4 μm respectively. These nanofibers were selectively grafted on one side of a 100% cotton fabric using a special apparatus. Prior to the grafting, cotton fabrics were modified with partial carboxymethylation to encourage cotton fiber nanofiber interactions. The surface modification was confirmed by Fourier transform infrared spectroscopy (FT-IR) peaks at 1594 cm-1 and 1735 cm-1 due to the presence of carboxylic acid functionality in modified cotton fabrics. Scanning electron microscope (SEM) study of the nanofiber grafted cotton fabrics showed that nanofibers were adhered to the cotton fabrics. Elemental analysis confirmed that side selective grafting of nanofiber has taken place due to the peak at 0.394 keV which attributes to the presence of nitrogen element in chitin nanofibers. This peak was absent in the other side of the fabric which was not coated with chitin nanofibers. Amount of adhered nanofibers was seen to increase with the increase of nanofiber concentration used in grafting as confirmed by Kjeldahl analysis. A possible mechanism of cotton fiber-nanofiber interactions is introduced. © 2014 Elsevier Ltd. All rights reserved.

Tissera N.D.,Sri Lanka Institute of Nanotechnology | Wijesena R.N.,Sri Lanka Institute of Nanotechnology | Perera J.R.,Sri Lanka Institute of Nanotechnology | De Silva K.M.N.,Sri Lanka Institute of Nanotechnology | Amaratunge G.A.J.,Sri Lanka Institute of Nanotechnology
Applied Surface Science | Year: 2015

We report for the first time hydrophobic properties on cotton fabric successfully achieved by grafting graphene oxide on the fabric surface, using a dyeing method. Graphite oxide synthesized by oxidizing natural flake graphite employing improved Hummer's method showed an inter layer spacing of ∼1 nm from XRD. Synthesized graphite oxide was exfoliated in water using ultrasound energy to obtain graphene oxide (GO). AFM data obtained for the graphene oxide dispersed in an aqueous medium revealed a non-uniform size distribution. FTIR characterization of the synthesized GO sheets showed both hydrophilic and hydrophobic functional groups present on the nano sheets giving them an amphiphilic property. GO flakes of different sizes were successfully grafted on to a cotton fabric surface using a dip dry method. Loading different amounts of graphene oxide on the cotton fiber surface allowed the fabric to demonstrate different degrees of hydrophobicity. The highest observed water contact angle was at 143° with the highest loading of graphene oxide. The fabric surfaces grafted with GO also exhibits adhesive type hydrophobicity. Microscopic characterization of the fiber surface using SEM and AFM reveals the deposition of GO sheets on the fiber surface as a conformal coating. Analysis of the fabric surface using UV-vis absorption allowed identification of the ratio of hydrophobic to hydrophilic domains present on the GO coated cotton fabric surface. Hydrophobic properties on cotton fabric are ascribed to two dimensional amphiphilic properties of deposited GO nano sheets, which successfully lower the interfacial energy of the fabric surface. © 2014 Elsevier B.V. All rights reserved.

Wijesena R.N.,Sri Lanka Institute of Nanotechnology | Tissera N.D.,Sri Lanka Institute of Nanotechnology | Perera R.,Sri Lanka Institute of Nanotechnology | Nalin De Silva K.M.,Sri Lanka Institute of Nanotechnology | Amaratunga G.A.J.,Sri Lanka Institute of Nanotechnology
Journal of Molecular Catalysis A: Chemical | Year: 2015

Effect of different levels of slight carboxymethylation of cotton cellulose was investigated for improved attachment of photocatalytic TiO2 nanoparticles on cotton fabrics using sodium monochloroacetate under an alkali condition. Surface modification was confirmed by FTIR using two characteristic peaks located at 1734 and 1594 cm-1 which occur due to presence of carboxylic and carboxylate functionality on modified cotton fabrics. These fabrics were then grafted with TiO2 nanoparticles (Aeroxide©P25) using a special apparatus to obtain self-cleaning fabrics. Morphology of the treated samples was characterized by atomic force microscopy and scanning electron microscopy which showed uniform coating of TiO2 nanoparticles on surface modified fabrics. Crystallinity of the coatings was evaluated using X-ray diffraction spectroscopy. Photocatalytic performance was evaluated for methyl orange as a model stain under UV-A and B exposure (200 W/m2) using a spectrophotometer. Results indicated that the number of surface carboxylic acid groups increase with the increase of concentration of sodium monochloroacetate used in surface modification reaction. Higher degree of surface modification increased the loading of TiO2 nanoparticles on cotton fabrics and hence the degree of photocataltic stain removal activity. © 2014 Elsevier B.V. All rights reserved.

Butt H.,University of Cambridge | Dai Q.,University of Cambridge | Rajasekharan R.,University of Cambridge | Wilkinson T.D.,University of Cambridge | And 2 more authors.
Applied Physics Letters | Year: 2011

We report enhanced reflection displayed by arrays of silicon based inverted nanocones. Theoretical studies suggest that such arrays display enhanced reflection and photonic band gaps within the optical and near infrared regions. Measured results show three to four fold enhancement in reflection and agree well with calculations. Such arrays can be used to enhance infrared reflection in photovoltaic devices which mostly contribute towards heating. © 2011 American Institute of Physics.

Wijesena R.N.,Sri Lanka Institute of Nanotechnology | Tissera N.D.,Sri Lanka Institute of Nanotechnology | De Silva K.M.N.,Sri Lanka Institute of Nanotechnology
Carbohydrate Polymers | Year: 2015

A method of coloration of cotton fabrics with nano chitosan is proposed. Nano chitosan were prepared using crab shell chitin nanofibers through alkaline deacetylation process. Average nano fiber diameters of nano chitosan were 18 nm to 35 nm and the lengths were in the range of 0.2-1.3 μm according to the atomic force microscope study. The degree of deacetylation of the material was found to be 97.3%. The prepared nano chitosan dyed using acid blue 25 (2-anthraquinonesulfonic acid) and used as the coloration agent for cotton fibers. Simple wet immersion method was used to color the cotton fabrics by nano chitosan dispersion followed by acid vapor treatment. Scanning electron microscope and atomic force microscope study of the treated cotton fiber revealed that the nano chitosan were consistently deposited on the cotton fiber surface and transformed in to a thin polymer layer upon the acid vapor treatment. The color strength of the dyed fabrics could be changed by changing the concentration of dyed nano chitosan dispersion. © 2015 Elsevier Ltd. All rights reserved.

Loading Sri Lanka Institute of Nanotechnology collaborators
Loading Sri Lanka Institute of Nanotechnology collaborators